U.S. patent application number 14/519174 was filed with the patent office on 2016-04-21 for method for printing colored and white toner using a device link profile.
The applicant listed for this patent is Chung-Hui Kuo. Invention is credited to Chung-Hui Kuo.
Application Number | 20160109839 14/519174 |
Document ID | / |
Family ID | 55749000 |
Filed Date | 2016-04-21 |
United States Patent
Application |
20160109839 |
Kind Code |
A1 |
Kuo; Chung-Hui |
April 21, 2016 |
METHOD FOR PRINTING COLORED AND WHITE TONER USING A DEVICE LINK
PROFILE
Abstract
A method for printing on a receiver with a plurality of colored
dry inks including dry black ink and a dry white ink, the method
includes the steps of providing a set of multidimensional look-up
tables for transforming a set of color channel inputs to a set of
colored channel outputs; inputting a set of color values to the
multidimensional look-up table, which values corresponds to a color
rendition at each pixel location of the receiver; wherein the
multidimensional look-up table outputs a new set of laydown values
corresponding to the input channels and a white laydown at each
pixel location; and printing the laydown values at each pixel
location with the plurality of colored dry inks and dry white
ink.
Inventors: |
Kuo; Chung-Hui; (Fairport,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kuo; Chung-Hui |
Fairport |
NY |
US |
|
|
Family ID: |
55749000 |
Appl. No.: |
14/519174 |
Filed: |
October 21, 2014 |
Current U.S.
Class: |
399/53 |
Current CPC
Class: |
G06K 15/1878 20130101;
G03G 15/01 20130101; G03G 15/6585 20130101; G03G 15/50
20130101 |
International
Class: |
G03G 15/00 20060101
G03G015/00; G03G 15/01 20060101 G03G015/01 |
Claims
1. A method for printing on a receiver with a plurality of colored
dry inks including dry black ink and a dry white ink, the method
comprising the steps of: determining a laydown amount of color inks
and black ink at each pixel by computing an input value at each
pixel location from an input file; providing a look-up table having
a set of one dimensional look-up tables for each of the colored
inks and black ink, wherein the look-up table receives a colorant
value corresponding to a laydown of the color inks and the black
ink at each corresponding pixel location of the receiver; wherein
the look-up table determines a laydown of white ink at each pixel
location depending on the laydown of the colored inks and black
ink; and printing the laydown of white ink, color inks and black
ink with the plurality of colored dry inks and dry white ink.
2. The method as in claim 1 further comprising using opacity of the
colored inks to determine the set of one dimensional look-up table
transforms.
3. The method as in claim 1 further comprising using desired level
of grey component removal of the colored inks to determine the set
of one dimensional look-up table transforms.
4. The method as in claim 1 further comprising using properties of
the receiver to determine the set of one dimensional look-up table
transforms.
5. The method as in claim 4, wherein the properties include the
color of the receiver, type of the receiver or reflectance of the
receiver.
6. The method as in claim 1, wherein the one dimensional look-up
table transform depends on order of laydown of the colored, black
and white ink on the receiver.
7. A method for printing on a receiver with a plurality of colored
dry inks including dry black ink and a dry white ink, the method
comprising the steps of: providing a set of multidimensional
look-up tables for transforming a set of color channel inputs to a
set of colored channel outputs; inputting a set of color values to
the multidimensional look-up table, which values corresponds to a
color rendition at each pixel location of the receiver; wherein the
multidimensional look-up table outputs a new set of laydown values
corresponding to the input channels and a white laydown at each
pixel location; printing the laydown values at each pixel location
with the plurality of colored dry inks and dry white ink; and using
desired level of grey component removal of the colored inks to
determine the multidimensional look-up table transforms.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] Reference is made to commonly assigned U.S. patent
application Ser. No. ______ (Docket No. K001571/PCW) concurrently
filed by Chung-Hui Kuo, entitled "Method For Printing Colored And
White Toner Using A Look-Up Table", and commonly assigned U.S.
patent application Ser. No. ______ (Docket No. K001904/PCW)
concurrently filed by Chung-Hui Kuo, entitled "An Apparatus For
Printing Colored And White Toner".
FIELD OF THE INVENTION
[0002] The present invention generally relates to
electrophotographic printers and, more particularly, to
electrophotographic printers that deposit "dry" white ink (commonly
referred to as white toner) in a controlled amount for cost
efficiencies and image quality.
BACKGROUND OF THE INVENTION
[0003] Electrophotographic printers produce images by depositing
toner on receivers (or "imaging substrates"), such as pieces or
sheets of paper or other planar media, glass, fabric, metal, or
other objects. Printers typically operate using subtractive color:
a substantially reflective receiver is over-coated image-wise with
cyan (C), magenta (M), yellow (Y), black (K), and other colorants.
Other toner compositions can also be used to produce effects beyond
simple image appearance.
[0004] In electrophotography, there is a need to deposit white
toner in combination with colored toner for various purposes such
as image quality and the like. The prior art discussed below
deposits white ink and other color toner on the receiver.
[0005] For example, U.S. Patent Publication 2009/0220695 A1
discloses a method of creating a record medium using an ink jet
process by which a non-white background can be completely hidden.
This is achieved by printing a metallic ink first and then a white
pink. Wherever there is an overlap between the two layers, an
opaque layer is formed which completely hides the background color
or transparency of the medium. A combination of metallic and white
layers creates the opaque layer which is extremely white because of
the scattering by the white layer and reflecting properties of the
metallic layer.
[0006] U.S. Patent Publication 2011/0234660 A1 discloses a method
of printing on a transparent medium by IJ process using color inks,
metallic ink and white ink. The opaque areas are created by the
process described in the '695 disclosure above. Use of white and
metallic provides the cost advantage as well as be able to provide
the desired luster effects. The image is viewed from the
non-printed side for transparent substrate where the white layer is
uniformly applied farthest from the medium. From opaque medium,
white is applied first and then metallic and finally the color inks
are jetted. The metallic layer serves as a specialty gloss layer to
provide different effects and opacity.
[0007] U.S. Patent Publication 2013/0145383 A1 discloses an inkjet
recording method which uses a white overlaying layer. The process
is designed for remote proofing in which a longitudinal film is
passed through two separate IJ stations. The substrate may contain
an ink reception layer.
[0008] If the substrate is opaque, white is first laid down
uniformly and after white layer is dried, color image is applied
above it and dried again. On the other hand, when the substrate is
transparent, color image is applied first and then dried. This is
followed by the uniform application of white inkjet drops over the
entire color image areas which are then dried again. In another
variation, the white can be applied on the opposite surface in the
case of a transparent substrate. Because the white is inkjet based,
the preferred pigments are hollow or porous to avoid settling of
heavy titania based white pigment. It further discloses an
"inverse" type white ink application [0054 and 0057]; however, the
white usage is based on total amount allowed by the substrate.
[0009] Although satisfactory, in U.S. Patent Publication
2009/0220695 A1, there is no adjustment of the white laydown with
respect to the subsequent color inks, and two layers or more layers
are required to create this opaque image. In U.S. Patent
Publication 2011/0234660 A1, which is an inkjet process, there is
no control of white ink based on color ink density; white is
printed farthest from the viewing side, behind colors, not
alongside. In U.S. Patent Publication 2013/0145383 A1, two printing
stations are used, not one printing station, and the total white
amount can exceed the total non-white amount ink. The present
invention includes the advantages of adjusting the white laydown
relative to color toner layers which reduces total toner cost,
preserves the possible special visual effect provided by
specialized substrates such as metallic/pearlescent substrate, and
optimizes printable color gamut.
SUMMARY OF THE INVENTION
[0010] The present invention is directed to overcoming one or more
of the problems set forth above. Briefly summarized, according to
one aspect of the invention, the invention resides in a method for
printing on a receiver with a plurality of colored dry inks
including dry black ink and a dry white ink, the method comprising
the steps of providing a set of multidimensional look-up tables for
transforming a set of color channel inputs to a set of colored
channel outputs; inputting a set of color values to the
multidimensional look-up table, which values corresponds to a color
rendition at each pixel location of the receiver; wherein the
multidimensional look-up table outputs a new set of laydown values
corresponding to the input channels and a white laydown at each
pixel location; and printing the laydown values at each pixel
location with the plurality of colored dry inks and dry white
ink.
[0011] These and other objects, features, and advantages of the
present invention will become apparent to those skilled in the art
upon a reading of the following detailed description when taken in
conjunction with the drawings wherein there is shown and described
an illustrative embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above and other objects, features, and advantages of the
present invention will become more apparent when taken in
conjunction with the following description and drawings wherein
identical reference numerals have been used, where possible, to
designate identical features that are common to the figures, and
wherein:
[0013] While the specification concludes with claims particularly
pointing out and distinctly claiming the subject matter of the
present invention, it is believed that the invention will be better
understood from the following description when taken in conjunction
with the accompanying drawings, wherein:
[0014] FIG. 1 is an electrophotographic printer useful for
implementing the present invention;
[0015] FIG. 2 is a block diagram illustrating details of the logic
and control unit and its interaction with printing modules of the
present invention;
[0016] FIG. 3 is an alternative embodiment of the logic and control
unit and its interaction with printing modules of the present
invention;
[0017] FIG. 4 is a third embodiment of the logic and control unit
and its interaction with printing modules of the present invention;
and
[0018] FIG. 5 is a fourth embodiment of the logic and control unit
and its interaction with printing modules of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Before discussing the present invention, it is useful to
understand the term "dry ink" as used herein. In this regard, dry
ink refers to toner particles deposited on a substrate which are
later fixed to the substrate by pressure, heat or both. In
contrast, liquid ink refers to inkjet processes where liquid ink is
deposited which then dries for forming an image on a substrate.
[0020] In the following description, some embodiments will be
described in terms that would ordinarily be implemented as software
programs. Those skilled in the art will readily recognize that the
equivalent of such software can also be constructed in hardware.
Because image manipulation algorithms and systems are well known,
the present description will be directed in particular to
algorithms and systems forming part of, or cooperating more
directly with, embodiments described herein. Other aspects of such
algorithms and systems, and hardware or software for producing and
otherwise processing the image signals involved therewith, not
specifically shown or described herein, are selected from such
systems, algorithms, components, and elements known in the art.
Given the system as described herein, software not specifically
shown, suggested, or described herein that is useful for
implementation of the invention is conventional and within the
ordinary skill in such arts.
[0021] FIG. 1 is an elevational cross-section illustrating portions
of a typical electrophotographic printer 100 useful with various
embodiments. Printer 100 is adapted to produce print images, such
as single-color (monochrome), CMYK, CMYKF (five-color), or with the
addition of a 6.sup.th development station (which is not shown)
hexachrome images, on a receiver (multicolor images are also known
as "multi-component" images). Images can include either or a
combination of text, graphics, photos, and other types of visual
content. One embodiment involves printing using an
electrophotographic print engine having six sets of single-color
image-producing or printing stations or modules arranged in tandem,
but more or fewer than six colors can be combined to form a print
image on a given receiver. Other electrophotographic writers or
printer apparatus can also be included. Various components of the
printer 100 are shown as rollers; other configurations are also
possible, such as configurations having belts.
[0022] The printer 100 is an electrophotographic printing apparatus
having a number of tandemly arranged electrophotographic
image-forming printing modules 31, 32, 33, 34, 35, also known as
electrophotographic imaging subsystems. Each printing module 31,
32, 33, 34, 35 produces a single-color toner image for transfer
using a respective transfer subsystem 50 (for simplicity and
clarity, only one is labeled) to a receiver 42 successively moved
through the modules. The receiver 42 is transported from a supply
unit 40, which can include active feeding subsystems as known in
the art, into the printer 100. In various embodiments, the visible
image can be transferred directly from an imaging roller to the
receiver 42, or from an imaging roller to one or more transfer
roller(s) or belt(s) in sequence in transfer subsystem 50, and then
to the receiver 42. The receiver 42 is, for example, a selected
section of a web of, or a cut sheet of, planar media such as paper
or transparency film.
[0023] Each printing module 31, 32, 33, 34, 35 includes various
components. For clarity, these are only shown in the printing
module 32. Around photoreceptor 25 are arranged, ordered by the
direction of rotation of photoreceptor 25, a charger 21, an
exposure subsystem 22, and toning station 23.
[0024] In the EP process, an electrostatic latent image is formed
on photoreceptor 25 by uniformly charging photoreceptor 25 and then
discharging selected areas of the uniform charge to yield an
electrostatic charge pattern corresponding to the desired image (a
"latent image"). The charger 21 produces a uniform electrostatic
charge on photoreceptor 25 or its surface. The exposure subsystem
22 selectively image-wise discharges photoreceptor 25 to produce a
latent image. The exposure subsystem 22 can include a laser and
raster optical scanner (ROS), one or more LEDs, or a linear LED
array.
[0025] After the latent image is formed, charged toner particles
are brought into the vicinity of the photoreceptor 25 by the toning
station 23 and are attracted to the latent image to develop the
latent image into a visible image. Note that the visible image may
not be visible to the naked eye depending on the composition of the
toner particles (for example clear toner). The toning station 23
can also be referred to as a development station. The toner can be
applied to either the charged or discharged parts of the latent
image. The toner particles can have a range of diameters, for
example less than 8 micrometer, on the order of 10-15 micrometer,
up to approximately 30 micrometer, or larger ("diameter" refers to
the volume-weighted median diameter, as determined by a device such
as a Coulter Multisizer).
[0026] After the latent image is developed into a visible image on
photoreceptor 25, a suitable receiver 42 is brought into
juxtaposition with the visible image. In the transfer subsystem 50,
a suitable electric field is applied to transfer the toner
particles of the visible image to the receiver 42 to form the
desired print image 38 on the receiver 42, as shown on receiver
42A. The imaging process is typically repeated many times with
reusable photoreceptors 25.
[0027] The receiver 42A is then removed from its operative
association with photoreceptor 25 and subjected to heat or pressure
to permanently fix ("fuse") print image 38 to receiver 42A. Plural
print images are overlaid on one receiver before fusing to form a
multi-color print image 38 on the receiver 42A.
[0028] Each receiver 42, during a single pass through the six
printing modules 31, 32, 33, 34, 35, can have transferred in
registration thereto up to five single-color toner images to form
an image. In one embodiment, printing module 31 forms black (K)
print images, 32 forms yellow (Y) print images, 33 forms magenta
(M) print images, 34 forms cyan (C) print images and 35 forms white
(W) print images. The receiver 42A is shown after passing through
the printing module 36. The print image 38 on receiver 42A includes
unfused toner particles.
[0029] Subsequent to transfer of the respective print images 38,
overlaid in registration, one from each of the respective printing
modules 31, 32, 33, 34, 35, the receiver 42A is advanced to a fuser
60, i.e. a fusing or fixing assembly, to fuse the print image 38 to
receiver 42A. A transport web 81 transports the
print-image-carrying receivers (e.g., 42A) to the fuser 60, which
fixes the toner particles to the respective receivers 42A by the
application of heat and pressure. The receivers 42A are serially
de-tacked from transport web 81 to permit them to feed cleanly into
fuser 60. The transport web 81 is then reconditioned for reuse at
cleaning station 86 by cleaning and neutralizing the charges on the
opposed surfaces of the transport web 81. A mechanical cleaning
station (not shown) for scraping or vacuuming toner off the
transport web 81 can also be used independently or with cleaning
station 86. The mechanical cleaning station can be disposed along
the transport web 81 before or after the cleaning station 86 in the
direction of rotation of the transport web 81.
[0030] The fuser 60 includes a heated fusing roller 62 and an
opposing pressure roller 64 that form a fusing nip 66 therebetween.
In one embodiment, the fuser 60 also includes a release fluid
application substation 68 that applies release fluid, e.g. silicone
oil, to fusing roller 62. Alternatively, wax-containing toner can
be used without applying release fluid to the fusing roller 62.
Other embodiments of fusers, both contact and non-contact, can be
employed. For example, solvent fixing uses solvents to soften the
toner particles so they bond with the receiver 42. Photoflash
fusing uses short bursts of high-frequency electromagnetic
radiation (e.g. ultraviolet light) to melt the toner. Radiant
fixing uses lower-frequency electromagnetic radiation (e.g.
infrared light) to more slowly melt the toner. Microwave fixing
uses electromagnetic radiation in the microwave range to heat the
receivers (primarily), thereby causing the toner particles to melt
by heat conduction, so that the toner is fixed to the receiver
42.
[0031] The receivers (e.g., receiver 42B) carrying the fused image
(e.g., fused image 39) are transported in a series from the fuser
60 along a path either to a remote output tray 69, or for duplex
printing, back to the printing modules 31, 32, 33, 34, 35 to create
an image on the backside of the receiver (e.g., receiver 42B), i.e.
to form a duplex print. Receivers (e.g., receiver 42B) can also be
transported to any suitable output accessory. For example, an
auxiliary fuser or glossing assembly can provide a clear-toner
overcoat. Printer 100 can also include multiple fusers 60 to
support applications such as overprinting, as known in the art.
[0032] In various embodiments, between the fuser 60 and the output
tray 69, the receiver 42B passes through the finisher 70. Finisher
70 performs various media-handling operations, such as folding,
stapling, saddle-stitching, collating, and binding.
[0033] The printer 100 includes the main printer apparatus logic
and control unit (LCU) 99, which receives input signals from the
various sensors associated with the printer 100 and sends control
signals to the components of the printer 100. The LCU 99 can
include a microprocessor incorporating suitable look-up tables and
control software executable by the LCU 99. It can also include a
field-programmable gate array (FPGA), programmable logic device
(PLD), microcontroller, or other digital control system. The LCU 99
can include memory for storing control software and data. Sensors
associated with the fusing assembly provide appropriate signals to
the LCU 99. In response to the sensors, the LCU 99 issues command
and control signals that adjust the heat or pressure within fusing
nip 66 and other operating parameters of fuser 60 for receivers.
This permits the printer 100 to print on receivers of various
thicknesses and surface finishes, such as glossy or matte.
[0034] Image data for writing by the printer 100 can be processed
by a raster image processor (RIP; not shown), which can include a
color separation screen generator or generators. The output of the
RIP can be stored in frame or line buffers for transmission of the
color separation print data to each of the respective LED writers,
e.g. for black (K), yellow (Y), magenta (M), cyan (C), and white
(W), respectively. The RIP or color separation screen generator can
be a part of printer 100 or remote therefrom. Image data processed
by the RIP can be obtained from a color document scanner or a
digital camera or produced by a computer or from a memory or
network which typically includes image data representing a
continuous image that needs to be reprocessed into halftone image
data in order to be adequately represented by the printer. The RIP
can perform image processing processes, e.g. color correction, in
order to obtain the desired color print. Color image data is
separated into the respective colors and converted by the RIP to
halftone dot image data in the respective color using matrices,
which comprise desired screen angles (measured counterclockwise
from rightward, the +X direction) and screen rulings. The RIP can
be a suitably-programmed computer or logic device and is adapted to
employ stored or computed matrices and templates for processing
separated color image data into rendered image data in the form of
halftone information suitable for printing. These matrices can
include a screen pattern memory (SPM).
[0035] Further details regarding printer 100 are provided in U.S.
Pat. No. 6,608,641, issued on Aug. 19, 2003, to Peter S.
Alexandrovich et al., and in U.S. Publication No. 20060133870,
published on Jun. 22, 2006, by Yee S. Ng et al., the disclosures of
which are incorporated herein by reference.
[0036] Referring to FIG. 2, there is shown in block diagram details
of the portion of the LCU 99 for rendering white toner based on the
amount of colored toner being rendered. The LCU 99 receives images
files, such as, but not limited to, RGB, CMYK, pdf, raster or
vector files, that are sent to a CMYK rendering engine 102 which
converts the particular image file into a standard CMYK format and
then separates the CYMK format file into individual color
components--Cyan component, Magenta component, Yellow component,
and Black component. These individual color components are then
each sent to either a one-dimensional transform 105a or a
one-dimensional look-up table (LUT) 105b. The transform 105a or LUT
105b takes the particular color component and obtains the
corresponding white laydown at each pixel location. It is noted
that the white color component varies according to the amount of
the particular color component as illustrated schematically in FIG.
2. The LUT 105b is in a table format in which corresponding values
are stored; transform 105a is a real-time look-up in which an
algorithm determines the corresponding white laydown; and look-up
table as used herein refers to either embodiment. The basic
algorithm is to deposit maximal amount of white toner on the area
of the media corresponding to the white point of the image, and
gradually reducing monotonically the amount of white toner laydown
relative to each increasing color toner laydown. The rate of white
toner laydown reduction is dependent on the opacity of each color
toner, the intended substrate's background color, and the toner
laydown sequence. For example, the black toner has very high
opacity. As a result, the white toner reduction rate relative to
the black toner can be higher than other color toners such as
yellow. Furthermore, the background color of the intended substrate
will also affect the white toner reduction rate relative to each
color toner laydown. For example, if the substrate is metallic,
since the substrate surface is very reflective, the purpose of the
white toner is simply to sufficiently block the underlying metallic
texture structure without losing the metallic appearance. The white
toner reduction rate will be much higher than that on a colored
card board substrate. The four 1-D transforms or LUTs (105a or
105b), one for each colorant, each output a value for the white
laydown (W1, W2, W3, W4). Those values are input to a computational
engine 110 that determines the print value for each pixel location
based on the white laydown values from each transform or LUT (105a
or 105b).
[0037] The determined value for W could be simply the smallest of
the set of white values (W1, W2, W3, W4), or it could be an overage
of the set of white values (W1, W2, W3, W4), or it could even be
the largest of the set of white values (W1, W2, W3, W4). The value
for the white ink laydown W and the original values for the
colorants (CMYK) are provided to the printing module 31-15 for
rendering and physical lay down and finishing of the colorants on
the receiver.
[0038] Referring to FIG. 3, there is shown an alternative
embodiment for rendering white toner based on the amount of colored
toner being rendered. The LCU 99 receives images files, such as,
but not limited to, RGB, CMYK, pdf, raster or vector files, that
are sent to the CMYK rendering engine 102 which converts the
received image file into a standard CMYK format and then separates
the CYMK format file into individual color components--C component,
M component, Y component, and K component. The CMY values are
combined in an effective laydown engine 120 to determine an
effective laydown of the colorants and then the effective laydown
is sent to either the one dimensional transform 105a or the one
dimensional LUT 105b, which is used to determine the desired
laydown of white ink W5 at each pixel location (the y values)
depending on the effective laydown of the colored inks (CMY). The
opaque black value K is provided to either a separate one
dimensional transform 105c or one dimensional LUT 105d which
correlates the laydown of the black ink (K) to another white
laydown W6 based on the black ink. In other words, the two 1-D
transforms or LUTs (either 105a or 105b and either 105c or 105d),
one for the effective CMY and one for the black K laydown, each
output a value for the white laydown (W5, W6). The W5 and W6 values
are input to the computational engine 110 that determines the print
value for each pixel location based on the white laydown values
from each transform or LUT (either 105a or 105b and either 105c or
105d). To determine the effective laydown of the colored ink (CMY),
first treat each distinct color toner as the same type of toner.
Within a unit area, then compute the percent of averaged coverage
of this new toner where the overlapped area of two of more color
toner is counted only once. This averaged coverage can also change
with respect to the halftone screen structure.
[0039] The determined value for W in this embodiment could be
simply the smallest of the set of white values (W5, W6), or it
could be an overage of the set of white values (W5, W6), or it
could even be the largest of the set of white values (W5, W6). The
value for the white ink laydown W and the original values for the
colorants (CMYK) are provided to the print engine modules 31-35 for
rendering and physical lay down and finishing of the colorants on
the receiver.
[0040] Referring to FIG. 4, there is shown a third embodiment for
rendering white toner based on the amount of colored toner being
rendered. The LCU 99 receives images files, such as, but not
limited to, RGB, CMYK, pdf, raster or vector files, that are sent
to a CMYK rendering engine 102 which converts the received image
file into a standard CMYK format and then separates the CYMK format
file into individual color components--C component, M component, Y
component, and K component. The CMYK values are combined in an
effective laydown engine 120 to determine an effective laydown of
the colorants and black and then the effective laydown is sent to
either the one dimensional LUT 105a or 105b, which is used to
determine the desired laydown of white ink W7 at each pixel
location (the y values) depending on the effective laydown of the
colored inks and black dry ink (CMYK). The 1-D transform or LUT
(105a or 105b) outputs a value for the white laydown (W7). That
value determines the white ink print value for each pixel location
based on the effective laydown of CMYK. The value for the white ink
laydown W7 and the original values for the colorants (CMYK) are
provided to the printing module 31-35 for rendering and physical
lay down and finishing of the colorants on the receiver.
[0041] Referring to FIG. 5, there is shown a fourth embodiment for
rendering white toner based on the amount of colored toner being
rendered. The LCU 99 receives images files, such as, but not
limited to, RGB, CMYK, pdf, raster or vector files, that are sent
to a CMYK rendering engine 102 which converts the received image
file into a standard CMYK format and then separates the CYMK format
file into individual color components--C component, M component, Y
component, and K component. The CMYK values are then combined using
a color profile known as the Device Link Profile 130 to determine
the desired laydown of all the dry inks, C'M'Y'K' and W'. The
effective laydowns are provided to the printing modules 31-35 for
rendering and physical lay down and finishing of the colorants on
the receiver. The advantage of utilizing a Device link profile to
provide proper white toner laydown relative to the color toner
laydown, such as C,M,Y,K, and possibly other supplemental accent
color toners, from the digital controller is its capability to
specify different amount of white toner laydown at different color
toner laydown composition on the intended printing substrate. A
printer output device link profile is composed of a
multidimensional LUT from N-color input channels to M-Color output
channels. In the case of creating a separate white toner layer, the
dimension of the input/output color channels is N and N+1
respectively. In one embodiment, each color toner is assigned with
its own opacity coefficient ranging from 0 to 1, where 0 means
complete transparent and 1 means complete opaque. For example, the
opacity coefficient for yellow toner is usually set as the lowest
among all color toners and the black toner is usually set to be 1.
Based on a chosen halftone screen set for every color channel, the
effective substrate-blocking ratio, Br, on a unit area by all color
toner laydown combined in the multidimensional LUT of the Device
link profile can be computed. The white toner laydown, W', is
inversely correlated with the computed substrate-blocking ratio,
for example, W=1-Br. This correlation function will also be
dependent on the selected substrate. At the same time, C'M'Y'K' are
computed taking into account grey component removal and the type of
substrate used.
[0042] Grey component removal is used by the Device link profile to
substitute a quantity of black ink for the grey component of the
CMY inks. The Device link profile uses properties of the receiver
to determine the multidimensional look-up table transforms, and
properties of the receiver include the color of the receiver, type
of the receiver or reflectance of the receiver. The Device link
profile also depends on order of laydown of the colored, black and
white toner on the receiver.
[0043] The present invention has been described in detail with
particular reference to certain preferred embodiments thereof, but
it will be understood that variations and modifications can be
effected within the spirit and scope of the invention.
PARTS LIST
[0044] 21 charger [0045] 22 exposure subsystem [0046] 23 toning
station [0047] 25 photoreceptor [0048] 31 printing module [0049] 32
printing module [0050] 33 printing module [0051] 34 printing module
[0052] 35 printing module [0053] 38 print image [0054] 39 fused
image [0055] 40 supply unit [0056] 42 receiver [0057] 42A receiver
[0058] 42B receiver [0059] 50 transfer subsystem [0060] 60 fuser
[0061] 62 fusing roller [0062] 64 pressure roller [0063] 66 fusing
nip [0064] 68 release fluid application substation [0065] 69 output
tray [0066] 70 finisher [0067] 81 transport web [0068] 86 cleaning
station [0069] 99 logic and control unit (LCU) [0070] 100 printer
[0071] 102 CMYK rendering engine [0072] 105a transform [0073] 105b
one-dimensional look-up table (LUT) [0074] 105c transform [0075]
105d one dimensional look-up table (LUT) [0076] 110 computational
engine [0077] 120 effective laydown engine [0078] 130 Device link
profile
* * * * *