Reproduction, adaptation, or translation
without prior written permission is prohibited,
except as allowed under the copyright laws.
The information contained herein is subject to
change without notice.
The only warranties for HP products and
services are set forth in the express warranty
statements accompanying such products and
services. Nothing herein should be construed
as constituting an additional warranty. HP shall
not be liable for technical or editorial errors or
omissions contained herein.
Edition 1, 3/2016
ENERGY STAR® and the ENERGY STAR® mark are
registered U.S. marks.
Conventions used in this guide
TIP:Tips provide helpful hints or shortcuts.
NOTE:Notes provide important information to explain a concept or to complete a task.
CAUTION:Cautions indicate procedures that you should follow to avoid losing data or damaging the
product.
WARNING!Warnings alert you to specic procedures that you should follow to avoid personal injury,
catastrophic loss of data, or extensive damage to the product.
ENWWiii
iv Conventions used in this guideENWW
Table of contents
1 Theory of operation ....................................................................................................................................... 1
System control ....................................................................................................................................................... 8
Formatter and data path ..................................................................................................................... 8
Engine control ..................................................................................................................................... 9
Print system operational states ....................................................................................................... 15
Paper-handling system ....................................................................................................................................... 17
Paper path zones ............................................................................................................................... 24
Servicing system .................................................................................................................................................. 28
Service sled ........................................................................................................................................ 30
Transmission system ........................................................................................................................................... 31
States ................................................................................................................................................. 32
Aerosol management system ............................................................................................................................. 34
Document feeder system (377/477/577/P57750 models) ............................................................................... 36
Document feed system ..................................................................................................................... 36
Rollers and sensors in the document feeder .................................................................................... 36
Restore the factory-set defaults ......................................................................................................................... 44
Menu access ......................................................................................................................................................... 44
Menu access on monochrome control panels .................................................................................. 45
Menu access on color control panels ................................................................................................ 47
Perform tap tests and interpret results .............................................................................................................. 49
10 tap test results (OOBE states) ...................................................................................................... 49
12 tap test results (REDI sensor values) ........................................................................................... 51
61 tap results (Align and color calibrations) ..................................................................................... 53
909 tap test results (BDD status) ...................................................................................................... 54
Verify that the pig tails have an adequate seal ................................................................................ 55
Index ........................................................................................................................................................... 151
viENWW
List of gures
Figure 1-1 Main components (352/452 models) ................................................................................................................. 2
Figure 1-2 Main components (377/477 models) ................................................................................................................. 3
Figure 1-3 Main components (552/P55250 models) ........................................................................................................... 4
Figure 1-4 Main components (577/P57750 models) ........................................................................................................... 5
Figure 1-5 System control .................................................................................................................................................... 8
Figure 1-9 Paper-handling system paper path (300/400 series) ...................................................................................... 17
Figure 1-10 Paper-handling system paper path (500 series) ............................................................................................ 18
Figure 1-15 Paper path zones (300/400 series) ................................................................................................................ 25
Figure 1-16 Paper path zones (500 series) ........................................................................................................................ 26
Figure 1-17 Servicing system components (300/400 series) ........................................................................................... 28
Figure 1-18 Servicing system components (500 series) ................................................................................................... 29
Figure 1-19 Service sled components ................................................................................................................................ 30
Figure 2-1 Printer status report—determining genuine HP ink usage ............................................................................. 68
Figure 2-2 Mark the Web wipe ............................................................................................................................................ 90
Document feeder system (377/477/577/P57750 models)
●
Scanning and image capture system (377/477/577/P57750 models)
●
Fax functions and operation (377/477/577/P57750 models)
ENWW1
Basic operation
Control panel
Output bin
Printbar
Service sled
Main input tray (Tray 2)
Optional trays (Trays 3 and 4)
Multipurpose tray
(Tray 1)
Ink collection unit
Optical
scan
carriage
Ink cartridges
Function structure
The printer consists of the following components.
Figure 1-1 Main components (352/452 models)
2Chapter 1 Theory of operationENWW
Figure 1-2 Main components (377/477 models)
Document feeder
Scanner
Control panel
Output bin
Printbar
Service sled
Main input tray (Tray 2)
Optional trays (Trays 3 and 4)
Multipurpose tray
(Tray 1)
Ink collection unit
Optical
scan
carriage
p
Ink cartridges
(
ENWWBasic operation3
Figure 1-3 Main components (552/P55250 models)
Control panel
Output bin
Printbar
Service sled
Main input tray (Tray 2)
Multipurpose tray
(Tray 1)
Duplex module\
Waste ink module
Optical
scan
carriage
Optional trays (Trays 3 and 4)
Ink cartridges
4Chapter 1 Theory of operationENWW
Figure 1-4 Main components (577/P57750 models)
Control panel
Output bin
Printbar
Service sled
Main input tray (Tray 2)
Optional trays (Trays 3 and 4)
Multipurpose tray(Tray 1)
Duplex module\
Waste ink module
Opticalscancarriage
Document feeder
Scanner
Ink cartridges
C
ontrol pane
l
O
utput bi
n
Printbar
Se
rvice
sled
M
ain input tray (Tray 2
)
O
ptional trays (Trays 3 and 4
)
Mul
tipurpose tray
(
Tray 1
)
Duplex module
\
Waste ink module
le
O
ptica
l
scan
c
arriage
Document feeder
Sc
anner
nk cartr
idg
es
The printer contains the following systems:
●
Engine control system
●
Print subsystem
●
Paper-handling system
●
Servicing system
●
Aerosol management system
●
Scanner and document feeder system
ENWWBasic operation5
Two elements inuence the printer architecture:
●
The rst is the need to orient the printbar with its active face downwards and statically located above
the print media. This requires the printbar to move vertically to access its active face.
●
The second is producing face-down output. Rather than ejecting the page face-up immediately after the
ink is applied, the printer routes the printed page up and back over the printbar to eject face-down.
Operation sequence
The engine-control system on the formatter PCA controls the operational sequences. The following table
describes durations and operations for each period of a print operation from when the printer is turned on
until the motor stops rotating.
Table 1-1 Operation sequence
PeriodDurationPurpose
Initial startup and
calibrations
Servicing operationsPerformed when the printbar is
Print preparationFrom the time the printer
When the printer is set up for the
rst time from the factory.
entering the capping state after
printing, when leaving the
capping state after a print job is
initiated, or during extended
print jobs.
receives a printer command until
paper enters the print zone.
This period gets the printer ready to print for the rst time.
●
Fluid replacement—The printer ushes the shipping and
handling uid out of the printbar and replaces it with ink.
●
Die alignment—The printer aligns the 10 die on the printbar
active face.
●
Die density leveling—The printer measures and compensates
for the drop variation.
Servicing maintains print quality by removing debris and excess ink
and replacing missing nozzles.
●
Nozzle presence detection—The optical scan carriage detects
and disables inoperable nozzles, and replaces them with
operable nozzles.
●
Printbar servicing—The web wipe on the service sled moves
under the printbar to clean the active face and res the nozzles
into the ink collection unit to clear clogs.
Prepares the printer for a print job.
●
The printbar leaves the capping state as the service sled
moves away from the printbar.
●
If needed, some servicing occurs.
●
The printbar lowers to the printing position. The media type
and printing mode determine the print zone height.
●
The printer picks media from one of the input trays.
●
Every page from Tray 1 is scanned. For Tray 2 and optional
Trays 3 and 4, the printer performs media edge detection after
printing the rst sheet after the tray is loaded. The last sheet
of each job is also scanned if at least ve sheets have been
printed.
●
The printer monitors environmental conditions. The printer
can slow the print speed if conditions are signicantlydierent
than a normal oice environment (23° C (73.4° F), 50% relative
humidity).
●
The formatter PCA processes print data and transmits the data
to the printbar.
6Chapter 1 Theory of operationENWW
Table 1-1 Operation sequence (continued)
PeriodDurationPurpose
PrintingFrom the end of the preparation
period until the last sheet is
delivered.
End of print jobPerformed after the print job is
completed, and continues until
the next job is initiated.
StandbyThe printer is sitting idle, waiting
for the next print job to be
initiated.
Processes the print job.
●
As the page travels through the print zone, the printbar applies
ink to the page.
●
Simplex print job—the page moves up, over the printbar, and
out to the output bin (face-down).
●
Duplex print job—the page moves up until the trailing edge is
40 mm (1.5 in) past the star-wheel jam reective sensor. The
page reverses direction down through the duplex path and
underneath the ink collection unit. Then, it reenters the print
zone, where the printbar applies ink to the second side.
●
The process continues until all the pages of the print job are
completed. The process can be interrupted by occasional
nozzle presence detection and servicing events, if the job
includes many pages.
This period puts the printer in a state where it’s ready for the next
print job.
●
If needed, some servicing occurs.
●
The printbar moves to the capping position after a short dwell
interval.
●
The service sled moves to cap the printbar.
This period is intended to conserve energy when the printer is
sitting idle. Certain functions might be disabled to save power and
then re-started only when needed. The printer has two sleep
modes:
●
Idle mode—The printbar is capped and the printer is ready to
immediately start a new job
●
Sleep mode—After the printer is inactive for about 10 minutes
(a setting that can be adjusted from the control panel or the
Embedded Web Server), the control panel turns o and the
power LED blinks to indicate the unit is in Sleep mode. All
printer functions are available.
ENWWBasic operation7
System control
Power supply
Engine control
Motor + sensor drive
Formatter
I/O, PDL, UI control
I/O
Datapath
ASIC +memory
Printbar
40,000 nozzles
Pen I/F
• Pen energy control
• Pen voltage
sequencing
• Signal integrity
• Ink-short protection
• Printhead
interconnects
• Ink supply
The system control coordinates all the other systems, according to commands from the formatter.
Figure 1-5 System control
The system consists of ve major sections.
●
Formatter
●
Data path
●
Engine control
●
Pen interface
●
Power supply
The engine PCA integrates both formatter and engine control electronics onto a single assembly. The wireless
radio unit (wireless models only) plugs into the back of the engine PCA, and the fax connects to the PCA via a
short at-exible cable (FFC).
Formatter and data path
The formatter controller ASIC controls the input/output (I/O) control, the user interface, and the rendering of
page description language les into printer-specic commands.
Input/output (I/O) control
The printers support 10/100 Ethernet, 802.11 wireless (HP wireless direct models), a rear USB host port, a
control panel USB host port (552/P55250/377/477/577/P57750 models), and an analog fax port
(377/477/577/P57750 models). For Ethernet networks, the formatter ASIC uses a separate integrated circuit
(Broadcom 5241) to provide the physical network layer.
The formatter ASIC controls the USB device and USB host as well.
Wireless I/O is provided via a separate radio module.
User interface
The printers contain either a 2-inch (352/452 models) monochrome display or an 4.3-inch (552/
P55250/377/477/577/P57750 models) color graphics display. An icon on the control panel of wireless
models denotes that the wireless feature is enabled. The 552, P55250, 377, 477, 577, and P57750 models
include a walk-up USB host port for connection to thumb drives.
8Chapter 1 Theory of operationENWW
Formatter digital ASIC
The formatter digital ASIC contains dual ARM CPUs (1.2 GHz and 600MHz) that execute rmware code that
provides high-level device control. The digital ASIC uses a standard PCle interface to pass data to the engine
control ASIC.
Formatter analog ASIC
The formatter analog ASIC generates the system voltage for the formatter, drives the scanner and ADF
motors, manages the real-time clock, and drives the fax speaker. Also, the engine uses this ASIC to drive the
ISS pumps, solenoids, and aerosol fan.
Real-time clock
The real-time clock (RTC) allows the fax module to time-stamp outgoing faxes. In addition, it determines the
elapsed time between printhead and ISS calibration events. The RTC uses a special block inside the engine
analog ASIC, along with a crystal and a battery.
Engine control
The engine controller digital ASIC receives high-level commands from the formatter, and it then provides lowlevel control to the print mechanism. In particular, the engine controller digital ASIC and its rmware control
motors, system sensors, and the printbar. The engine controller analog ASIC integrates motor drivers, voltage
regulators, sensor interfaces, and supervisory circuits.
Engine controller digital ASIC
The engine controller digital ASIC has a high-performance 480 MHz ARM CPU and DSP co-processors that
execute rmware code to provide low-level engine control. It also drives the printbar via 15 high-speed LVDS
transmission lines, which are routed from the engine PCA to the printbar via two large FFC cables. The engine
controller digital ASIC receives pre-rendered data from the formatter digital ASIC over a standard PCle
interface.
When a product has entered sleep mode, many functions of the printer have gone into a low-power mode. If a
print job is received while the product is in sleep mode, the printer will take a short period of time to "wake
up". This can take up to 15 seconds, which will delay the rst page out (FPO) time accordingly.
Engine controller analog ASIC
The engine uses two analog ASICs to generate the system voltages for the engine, drive the engine motors,
control various engine sensors, and monitor printbar power delivery for correct operation.
The engine has seven motors, some of which are shared with other subsystems:
●
Pick motor
●
Feed motor
●
Duplex motor
●
Lift motor
●
Eject motor
●
Sensor carriage motor
●
Aerosol fan motor
ENWWSystem control9
Each one is a DC motor with encoder feedback, to provide precision servo control. These motors are driven
directly by one of the engine analog ASICs. Small DC motors also are used to drive the ISS pump and the
aerosol fan. There are solenoids that actuate the ejection ap and the ISS priming system.
The printer uses many sensors to track the media as it travels through the paper path. Most of these are
optical REDI sensors, which are used in conjunction with mirrors to sense the presence or absence of paper in
a particular location. These are carefully aligned and calibrated at the factory, so care must be taken when
servicing these sensors. See the Remove and Replace chapter in the repair manual for more details.
Other printed circuit-board assemblies (PCAs)
In addition to hosting the system ASICs, the engine PCA is home to many circuits needed to interface to
sensors and other sub-system components. In some cases, this circuitry is located on a smaller remote PCA
(SLB) to optimize cable interconnects.
●
Humidity sensor—The humidity sensor causes the printer to adjust printing speed if ambient conditions
are outside the optimal humidity range. This sensor is calibrated at the factory to ensure maximum
accuracy.
●
Temperature sensor—The temperature sensor causes the printer to adjust printing speed if ambient
conditions are outside the optimal temperature range. In some printers, this sensor resides on a
separate, remote PCA.
●
Main tray presence sensor—The hall-eect sensor that detects if the main tray is properly engaged
resides on the back of the engine PCA. A small magnet on the back of the main tray actuates the sensor.
If the tray is fully engaged, the magnetic eld strength is suicient to trigger the sensor.
Additionally, the printer includes the following PCAs:
●
Front USB PCA—This PCA governs the control panel USB port.
●
Fax PCA—This PCA governs the printer fax module.
●
Duplex module presence sensor–This hall-eect sensor detects whether the duplex module is properly
seated.
●
Power button PCA—This PCA includes the power button and power LED, as well as interface cables to
the duplex module presence sensor and the MP tray empty REDI sensor.
●
Accessory tray interconnect PCA—This PCA provides communication to optional Tray 3.
●
Pick encoder distribution PCA—This PCA includes the pick motor encoder and the pick motor
interconnect cable.
●
Eject encoder distribution PCA—This PCA includes the eject motor encoder, plus the interconnect cables
to the eject motor and the aerosol fan.
●
Print zone distribution PCA—This PCA joins interconnect cables to the following sensors: separator REDI,
feed motion encoder, main tray empty sensor, Top of Form (TOF) REDI sensor, and the Print zone REDI
sensor.
●
REDI distribution PCA—This PCA includes hall-eect sensors that detect ink cartridge door and left door
positions. It also combines the interconnect cables for the eject REDI sensor, the upper paper path REDI
sensor, the lower paper path REDI sensor, and the eject ap opto ag sensor.
●
Sensor carriage PCA—This PCA includes a carriage motion encoder, a ZIM sensor, and the BDD sensor.
●
Printbar lift encoder distribution PCA—This PCA includes the printbar lift motion encoder and combines
interconnect cables to the printbar lift motor, carriage motor, and eject ap solenoid.
10Chapter 1 Theory of operationENWW
●
Duplex encoder PCA—This PCA contains the motion encoder for the duplex motor.
●
SHAID PCA—This PCA contains interfaces to the out-of-ink sensors for the ink cartridges, and combines
the interface cables to the acumen PCA, the ISS pump, and the ISS solenoids.
●
Acumen PCA—This PCA contains interfaces to the acumen memory devices for the ink cartridges.
Pen interface (I/F)
The printbar is the key component that dierentiates these printers from other inkjet printers. The
conventional approach is to print a page in horizontal swaths by moving a “scanning” printhead horizontally
xed sheet of paper, advancing the paper a xed amount, and then printing the next swath. With these
over a
printers, the paper moves underneath a xed page-wide printhead in a single smooth motion.
Single pass page-wide printing requires that data and power be delivered to the printbar at a very high rate,
while also maintaining good control of paper position as it moves past the printhead nozzles.
The engine PCA sends power and data to the printbar via two large atexible cables (36 and 38 pins). The
printbar PCA routes power and data to 10 printhead die, which are attached to the PCA using a exible tab
circuit and wire-bonding process.
The printers also contain electronics to control the ink supply station (ISS). The SHAID PCA detects low-ink
conditions. It gauges ink levels by means of electrically sensing the presence of ink and/or ink foam in the Xchamber. The SHAID PCA also collects and distributes electrical signals that drive the push-prime pump(s),
engage the solenoids, and read the ink supply acumen data. All are routed through a single 17-pin FFC from
the SHAID PCA to the engine PCA.
Each ink supply has a memory tag that stores information about its type of ink, the amount of ink remaining,
and other critical data. It uses a special authentication scheme to ensure that only genuine HP supplies are
used and the printer is not damaged by using invalid supplies. Acumen uses a two-line serial bus, which,
along with 3.3 V and ground, is cabled via the SHAID PCA to the engine PCA and the engine control digital ASIC.
Power supply
The power supply module converts 100-240 VAC to 34 VDC to power the system. The power supply module
has a sleep mode that reduces power consumption in system low-power modes. When in its sleep mode, the
power supply generates less than 4 W.
The power supply module supplies 34 V to the engine PCA. The power supply module has two operating
modes, depending upon the state of its nSLEEP input pin:
●
Printing: = up to 13 W ( nSLEEP = high logic level)
●
Sleep mode: = < 4 W ( nSLEEP = low logic level)
The power supply is a self-contained module that can be replaced if it is determined to be defective (see the
Remove and Replace chapter of the Repair Manual).
To ensure safe operation, the power supply will “latch o” if a persistent over-current fault condition exists.
This would typically be caused by a short-circuit from 34 V to ground in the printer. Less severe faults can
cause the power supply to latch o, if present for an extended period of time, or if the printer is operated
above the recommended operating temperature range.
NOTE:In some countries/regions, the printer is equipped with a high-voltage power supply in order to
prevent power supply unit failures due to over-voltage conditions.
ENWWSystem control11
Print subsystem
Printbar lift
Ink cartridges
Printbar
Optical
scan
carriage
The print subsystem includes the following components.
The printbar’s fundamental purpose is to convert the digital ring instructions from the printer electronics
into properly formed and timed microscopic drops of the four ink colors. The printbar spans the full width of a
letter/A4-size sheet (216 mm (8.5 in)), which allows the printbar to be statically positioned within the printer
and have the media move underneath it, printing the entire page in a single motion.
ENWWPrint subsystem13
Figure 1-8 Printbar components
1
4
23
Table 1-2 Printbar components
ItemDescription
1Ink cartridge connections
2Thermal inkjet (TIJ) die array
3Data/power ow and regulation
4Inkow channels and pressure regulation
The printbar has a xed array of 10 thermal inkjet (TIJ) die oriented in two staggered rows. Each die contains
more than 1,000 nozzles for each of the four ink colors—black (K), cyan (C), magenta (M) and yellow (Y).
Behind the die array are the ink ow channels and pressure regulation mechanisms that supply the die array
with ink at the proper pressure and ow. The die must also be fed power and data at the appropriate levels
and rates, which is the function of the onboard electronic circuitry. Finally, situated at the top of the printbar,
there are four ink cartridge receptacles, one for each color. These cartridges are linked by ow connections to
the rest of the printbar and supply the ink necessary for its operation.
A sensor technology called back-scatter drop detect (BDD) monitors printbar health and calibrations. This
system looks at the reection of the miniscule drops in ight, and then passes these signals through highspeed, high-gain, bandpass lters. A complex articial intelligence (AI) system decides which drop ejectors are
currently out of specications, and which are not.
After the AI system determines which drop ejectors are out of specication, the printer compensates for
them. Some ejectors use neighboring nozzles and at times even tiny amounts of other inks—whichever
combination of methods necessary to deliver the best print quality possible at that moment. In some cases,
fully half of the nozzles can be “out” without a noticeable degradation in quality. The compensation is done in
real time with a dedicated high-speed DSP. The system can scan portions of the system after print jobs, but it
is fully interruptible by new, incoming print jobs.
Printbar air management system
The printbar uses a passive air gain management system. Air can enter the printbar from the following
sources:
14Chapter 1 Theory of operationENWW
●
Die outgassing (from air in the ink)
●
Air entering nozzles due to temperature or pressure variations
●
Air entry through the printbar structure
●
Air entry through the nozzles due to shipment vibration
Air that enters the printbar is warehoused. There is no mechanism to remove the air in the eld. Of the
various mechanisms for air entry, the rst three are generally benign, and rarely cause issues during the
expected life of the printer. The fourth mechanism generally occurs during shipment. New printers are
shipped with the printbar taped—which limits the amount of air gained. If the printbar isn’t well restrained
during shipment, then air gain can be
air gain can be reduced either by ensuring that the printer stays on its base, or that the printbar is restrained.
Both would be best.
Printbar lift
The printbar lift is responsible for positioning the printbar within the printer and moving it up and down as
required. This vertical motion is both to establish proper spacing to the paper during printing, and to raise it
to either access the active face or perform necessary calibrations.
During printing, the lift mechanism sets the printbar height and paper height depending on the type of paper.
Ink cartridges
signicant. If the printer is shipped after removal of the printbar tape,
These printers have new, state-of-the-art pigmented inks. They are ltered using proprietary processes to
prevent printhead contamination. These inks are designed to produce optimal print quality on ColorLok oice
papers, but also produce very good print quality on regular oice papers and specialty paper.
Optical scan carriage
The optical scan carriage has optical sensors used for calibration. Its motion is along the long axis of the
printbar. These sensors are used by a number of printer calibration features that are important for proper
subsystem function. The BDD sensor is located on the optical scan carriage.
Print system operational states
The print subsystem has a number of distinct operational states besides active printing.
Startup
As it comes from the factory, the printbar is initially lled with an inert ink-substitute called Shipping and
Handling Fluid (SHF). This uid, essential for the manufacture and transportation of the printbar, must be
ushed and replaced with actual ink. This is accomplished during the Startup phase. The ushing process
automatically commences when ink supplies are inserted and the unit is powered up for the rst time. The
SHF is removed by sustained printbar operation and replaced by ink from the supplies. The process
terminates once all the SHF has been ushed from the printbar.
Special host supplies are supplied with the printer prior to its rst use. These supplies contain additional ink
so that there will be 100 percent ink level after the SHF is replaced with ink. These supplies can be used only
to initialize the printer. You cannot use them in another printer that has been initialized.
NOTE:The initial startup time is noticeably longer than the following regular startup times.
ENWWPrint subsystem15
Die alignment
Since 10 die comprise the printbar active face, each with associated positional tolerances, an active
calibration must be performed to prevent errors and allow a uniform ink application to the paper (without any
gaps or overlaps between adjacent die). This die alignment is done by printing a special diagnostic image on a
sheet of paper and then scanning it with the optical scan carriage. Die alignment is performed as part of
initial unit startup, and can be performed manually as part of the print quality recovery tool.
Die density leveling
Tolerances are also associated with the drops red by the individual printbar die. Another active calibration
measures and compensates for these variations to produce a visually uniform ink application to the paper.
Another set of diagnostic images is printed and scanned by the optical scan carriage to achieve this die
density leveling. Die alignment and die density leveling are usually paired together.
Nozzle presence detection
In printing, since all the ink is applied in a single smooth motion of the paper past the printbar, any inoperable
nozzle can show up as a noticeable streak. The operational state of each of the thousands of nozzles on the
printbar is periodically measured. The printbar lift raises the printbar, and the BDD assembly on the optical
scan carriage watches for drop presence as each nozzle is red. Inoperable nozzles are turned o and other
operable nozzles are used on subsequent printed pages to apply the missing ink. Nozzle presence detection is
fully interruptible by new, incoming print jobs.
Media edge position detection
The printer uses a learning algorithm to dene media center as a function of input source—Tray 1, Tray 2, or
optional Trays 3 and 4. The edge scan is located downstream of the print zone. As paper is scanned, the
media center database is updated. The image is registered to the page using the media center database.
Servicing and capping
When in the capped state, the printbar is fully raised, the service sled is positioned underneath, and the
printbar cap is engaged against the printbar active face. Servicing—the cleaning of the active face and the
ring of the nozzles—can occur either during Sleep2 mode or after extended time in storage. It can also occur
during extended print jobs.
Printing
The printing state begins by the printbar leaving the capping state, and lowering to the printing position after
the service sled moves out of the way. At the same time, a sheet of paper is picked from one of the three trays
and the leading edge staged at the entrance to the print zone. Once the print data has been sent, the sheet of
paper feeds at a constant velocity through the print zone and the printbar applies the ink.
In the case of one-sided printing, the inked sheet is moved up, over and out to the output tray. For two-sided
printing, the sheet is moved until its trailing edge is past the merge to the vertical path. The sheet is then
reversed down through the duplex path underneath the ink collection unit, and reintroduced into the print
zone for inking of the second side.
This process continues until all the pages of the print job are completed. If the print job is large enough, it can
be interrupted by servicing processes.
16Chapter 1 Theory of operationENWW
Paper-handling system
The paper-handling system moves paper through the printer according to commands from the formatter.
The following gures show the printer paper path.
Figure 1-9 Paper-handling system paper path (300/400 series)
ENWWPaper-handling system17
Figure 1-10 Paper-handling system paper path (500 series)
The paper path consists of the following major components:
●
Two integrated input trays plus one optional accessory tray
●
Four motors and a solenoid plus two more motors in the accessory tray
●
Duplex module
●
Sensors placed throughout the device, including the paper trays
18Chapter 1 Theory of operationENWW
●
1
2
3
13
14
15
16
17
18
19
20
21
22
23
24
1211 1089
999997
645
Multiple feed rollers, pinch rollers, star wheels, and media guides
●
Transmission components (gears, shafts, levers, swingarms) that interface with other subsystems such
as the printbar and service sled.
Components of the paper path move the paper from the input tray to a position 1 to 2 mm (.04 to .08 in)
underneath the printbar, and then deliver the printed result to the output tray. The combined orientations and
actions of the printbar, the printbar lift, and the paper path establish the print-zone, where the ink drops
move from the active face of the printbar to the paper.
The following gures show the printer sensors.
Figure 1-11 Printer sensors (300/400 series)
ENWWPaper-handling system19
Figure 1-12 Printer sensors (500 series)
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Table 1-3 Printer sensors
ItemDescriptionItemDescription
1Output ap jam sensor13Top of Form (TOF) REDI sensor (located on platen)
2Ambient temperature sensor14Feed roller encoder
3Ambient humidity sensor15Feed roller home sensor
4Tray 2 pickup tire home sensor16Duplex module presence sensor
5Tray 2 tray presence sensor17Print zone REDI sensor (located on platen)
20Chapter 1 Theory of operationENWW
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