Imaging cartridge system for inkjet printing mechanisms

An imaging inkjet cartridge system for an inkjet printing mechanism provides near photographic image quality, as well as crisp black text and line art. In a multi-pen carriage, typically for a tri-chamber full color (e.g. cyan, magenta and yellow) cartridge and a monochrome (e.g. black) cartridge, the monochrome cartridge may be replaced with an imaging inkjet cartridge. The full color cartridge carries full colorant concentrations of inks, while the imaging cartridge carries ink formulations having reduced colorant concentrations, such as cyan and magenta, with either a full or a reduced colorant concentration of black ink. The carriage may also carry all three cartridges (full color, black and imaging). Pens containing other color and concentration combinations may also be interchanged. A method is provided of retrofitting or upgrading an inkjet printing mechanism by replacing or interchanging cartridges, such as by replacing the monochrome cartridge with an imaging inkjet cartridge.

FIELD OF THE INVENTION 
The present invention relates generally to inkjet printing mechanisms, and 
more particularly to an imaging inkjet cartridge system that provides near 
photographic image quality, as well as crisp black text and line art. 
BACKGROUND OF THE INVENTION 
Inkjet printing mechanisms use inkjet cartridges, often called "pens," 
which shoot drops of liquid colorant, referred to generally herein as 
"ink," onto a page. Each pen has a printhead formed with very small 
nozzles through which the ink drops are fired. To print an image, the 
printhead is propelled back and forth across the page, shooting drops of 
ink in a desired pattern as it moves. The particular ink ejection 
mechanism within the printhead may take on a variety of different forms 
known to those skilled in the art, such as those using piezo-electric or 
thermal printhead technology. For instance, two earlier thermal ink 
ejection mechanisms are shown in U.S. Pat. Nos. 5,278,584 and 4,683,481, 
both assigned to the present assignee, Hewlett-Packard Company. In a 
thermal system, a barrier layer containing ink channels and vaporization 
chambers is located between a nozzle orifice plate and a substrate layer. 
This substrate layer typically contains linear arrays of heater elements, 
such as resistors, which are energized to heat ink within the vaporization 
chambers. Upon heating, an ink droplet is ejected from a nozzle associated 
with the energized resistor. By selectively energizing the resistors as 
the printhead moves across the page, the ink is expelled in a pattern on 
the print media to form a desired image (e.g., picture, chart or text). 
To clean and protect the printhead, typically a "service station" mechanism 
is mounted within the printer chassis so the printhead can be moved over 
the station for maintenance. For storage, or during non-printing periods, 
the service stations usually include a capping system which hermetically 
seals the printhead nozzles from contaminants and drying. Some caps are 
also designed to facilitate priming, such as by being connected to a 
pumping unit or other mechanism that draws a vacuum on the printhead. 
During operation, clogs in the printhead are periodically cleared by 
firing a number of drops of ink through each of the nozzles in a process 
known as "spitting," with the waste ink being collected in a "spittoon" 
reservoir portion of the service station. After spitting, uncapping, or 
occasionally during printing, most service stations have an elastomeric 
wiper that wipes the printhead surface to remove ink residue, as well as 
any paper dust or other debris that has collected on the face of the 
printhead. 
To improve the clarity and contrast of the printed image, recent research 
has focused on improving the ink itself. To provide faster, more waterfast 
printing with darker blacks and more vivid colors, pigment based inks have 
been developed. These pigment based inks have a higher solid content than 
the earlier dye based inks, which results in a higher optical density for 
the new inks. Both types of ink dry quickly, which allows inkjet printing 
mechanisms to form high quality images on readily available and economical 
plain paper. 
Early inkier printers used a single monochromatic pen, typically carrying 
black ink. Later generations of inkjet printing mechanisms used a black 
pen which was interchangeable with a tri-color pen, typically one carrying 
the colors of cyan, magenta and yellow within a single cartridge. The 
tri-color pen was capable of printing a "process" or "composite" black 
image, by depositing a drop of cyan, a drop of magenta and a drop of 
yellow all at the same location. Unfortunately, images printed with the 
composite black usually had rough edges, and the overall image, even the 
color portions, often had a non-black hue or cast, depending for instance, 
upon the type of paper used. 
The next generation of printers further enhanced the images by using a dual 
pen system. These dual pen printers provided a black pen along with a 
tri-color pen, both of which were mounted in a single carriage. These dual 
pen devices had the ability to print crisp, clear black text while 
providing full color images. As another answer to the dissatisfaction with 
the composite black images, a quad pen printing mechanism was developed. 
These quad pen printers carried four cartridges in a single carriage. Quad 
pen plotters were also developed, some of which carried four cartridges, 
one in each of four carriages. These quad printing mechanisms had a first 
pen carrying black ink, a second pen carrying cyan ink, a third pen 
carrying magenta ink, and a fourth pen carrying yellow ink. 
Unfortunately, both the quad pen printers and the dual pen printers 
produced images, such as photographic images, which had a "grainy" 
appearance. For example, when printing a light colored portion of an 
image, such as a flesh tone, yellow dots were printed and lightly 
interspersed with magenta dots. When viewed at a distance, these magenta 
dots provided a flesh tone appearance; however, upon closer inspection the 
magenta dots were quite visible, giving the image an undesirable grainy 
appearance. This grainy appearance was similar to the graininess seen in 
newspaper photographs, or in photos taken using the wrong speed ("ASA" or 
"ISO" rating) of photographic film in low light conditions. 
Indeed, inkjet priming mechanisms are known as "binary drop devices" 
because they form images by either placing a drop of ink on the print 
medium or by not firing. Not firing a droplet leaves either the print 
medium, or a previously printed drop(s), exposed to view. Unfortunately, 
such binary drop devices give inherently grainy images due to the visual 
"step" between the "drop on" and "drop off" regions. Worse yet, the larger 
the drops printed, the more grainy the resulting image appears, whether 
printing color or gray-scale images. 
Thus, the earlier inkjet printers, while providing crisp black text and 
bright vivid graphics and charts, failed to provide images of near 
photographic type quality, such as portraits, scenic landscapes, and other 
natural appearing images. Other devices have been used to provide high 
quality images, such as continuous tone devices, for instance, those using 
a dye sublimation processes. Unfortunately, these continuous tone devices 
are expensive, and very unlikely to be viable within the small office and 
home printer markets, which currently sell printers to consumers within 
the range of $200-$1,000 dollars. 
SUMMARY OF THE INVENTION 
One aspect of the present invention addresses the grainy image problem by 
providing an inkjet printing mechanism with at least two inkjet cartridges 
comprising either a first cartridge or a second cartridge, and a third 
cartridge. The first, second and third cartridges are responsive to first, 
second and third firing signals, respectively. The first and second 
cartridges contain at least one different ink formulation. The printing 
mechanism also has a carriage that receives the third cartridge, and that 
interchangeably receives the first cartridge or the second cartridge. The 
printing mechanism has a controller that generates the third firing 
signal. The controller also determines whether either the first cartridge 
or the second cartridge is installed in the carriage. The controller then 
generates the first firing signal when the first cartridge is installed, 
or the second firing signal when the second cartridge is installed. 
According to another aspect of the invention, a method is provided of 
retrofitting an inkjet printing mechanism having a carriage that carries 
first and second cartridges. The first cartridge carries a first ink 
formulation and is responsive to a first firing signal. The method 
includes the step of replacing the first cartridge in the carriage with a 
third cartridge. The third cartridge contains a third ink formulation and 
is responsive to a third firing signal. In a recognizing step, the 
replacement of the first cartridge with the third cartridge is recognized. 
In response to the recognizing step, in a generating step, the third 
firing signal is generated for the third cartridge. 
An overall goal of the present invention is to provide an inkjet printing 
mechanism which provides crisp black text and line art, bold color 
graphics and realistic images of near continuous-tone photographic 
quality, using a binary drop technology. 
A further goal of the present invention is to provide a method of recording 
realistic photographic type images on plain paper using an inkjet printer. 
Another goal of the present invention is to provide a retrofit system and 
method for upgrading a printing mechanism with an imaging inkjet cartridge 
system that provides near photographic image quality, while still 
retaining the option of using the original black and full-color cartridges 
for a faster print speed and crisper black edges when printing text or 
business graphics on plain paper.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIG. 1 illustrates an embodiment of an inkier printing mechanism, here 
shown as an inkjet printer 20, constructed in accordance with the present 
invention, which may be used for printing for business reports, 
correspondence, desktop publishing, and the like, in an industrial, 
office, home or other environment. A variety of inkjet printing mechanisms 
are commercially available. For instance, some of the printing mechanisms 
that may embody the present invention include plotters, portable printing 
units, copiers, cameras, video printers, and facsimile machines, to name a 
few. For convenience the concepts of the present invention are illustrated 
in the environment of an inkjet printer 20. 
While it is apparent that the printer components may vary from model to 
model, the typical inkjet printer 20 includes a chassis 22 surrounded by a 
housing or casing enclosure 24, typically of a plastic material. Sheets of 
print media are fed through a print zone 25 by a print media handling 
system 26. The print media may be any type of suitable sheet material, 
such as paper, card-stock, fabric, transparencies, mylar, and the like, 
but for convenience, the illustrated embodiment is described using paper 
as the print medium. The print media handling system 26 has a feed tray 28 
for storing sheets of paper before printing. A series of conventional 
paper drive rollers (not shown), driven by a stepper motor 30 and a drive 
gear assembly 32, may be used to move the print media from tray 28 into 
the print zone 25, as shown for sheet 34, for printing. 
After printing, the motor 30 drives the printed sheet 34 onto a pair of 
retractable output drying wing members 36. The wings 36 momentarily hold 
the newly printed sheet above any previously printed sheets still drying 
in an output tray portion 38 before retracting to the sides to drop the 
newly printed sheet into the outpost tray 38. The media handling system 26 
may include a series of adjustment mechanisms for accommodating different 
sizes of print media, including letter, legal, A-4, envelopes, etc., such 
as a sliding length adjustment lever 40, a sliding width adjustment lever 
42, and a sliding envelope feed plate 44. 
The printer 20 also has a printer controller, illustrated schematically as 
a microprocessor 45, that receives instructions from a host device, 
typically a computer, such as a personal computer (not shown). The printer 
controller 45 may also operate in response to user inputs provided through 
a key pad 46 located on the exterior of the casing 24. A monitor coupled 
to the computer host may be used to display visual information to an 
operator, such as the printer status or a particular program being run on 
the host computer. Personal computers, their input devices, such as a 
keyboard and/or a mouse device, and monitors are all well known to those 
skilled in the art. 
A carriage guide rod 48 is supported by the chassis 22 to slideably support 
an inkjet carriage 50 for travel back and forth, reciprocally, across the 
print zone 25 along a scanning axis 51. One suitable type of carriage 
support system is shown in U.S. Pat. No. 5,366,305, assigned to 
Hewlett-Packard Company, the assignee of the present invention. The 
carriage 50 is also propelled along guide rod 48 into a servicing region 
housing a service station 52, located within the interior of the casing 
24. The service station 52 may be any type of servicing device, sized to 
service the particular printing cartridges used in a particular 
implementation. Service stations, such as those used in commercially 
available printers, typically include wiping, capping and priming devices, 
as well as a spittoon portion, as described above in the background 
portion. One suitable preferred service station is commercially available 
in the DeskJet.RTM. 850C color inkjet printer, produced by Hewlett-Packard 
Company, the present assignee. 
The printer 20 also has a carriage drive gear and DC motor assembly 55, 
both coupled to drive an endless belt 56. The motor 55 operates in 
response to control signals received from the printer controller 45. The 
belt 56 may be secured in a conventional manner to the pen carriage 50 to 
incrementally advance the carriage along guide rod 48 in response to 
rotation of motor 55. To provide carriage positional feedback information 
to printer controller 45, an encoder strip 58 extends along the length of 
the print zone 25 and over the service station 52. A conventional optical 
encoder reader may also be mounted on the back surface of printhead 
carriage 50 to read positional information provided by the encoder strip 
58. The manner of attaching the belt 56 to the carriage, as well as the 
manner providing positional feedback information via the encoder strip 
reader, may be accomplished in a variety of different ways known to those 
skilled in the art. 
In the print zone 25, the media sheet 34 receives ink from an inkjet 
cartridge, such as a monochrome black ink cartridge 60 and/or a color ink 
cartridge 62. The cartridges 60 and 62 are also often called "pens" by 
those in the art. The illustrated color pen 62 is a tri-compartment, 
tri-color pen, although in some embodiments, a set of discrete monochrome 
pens may be used. While the color pen 62 may contain a pigment based ink, 
for the purposes of illustration, pen 62 is described as containing three 
dye based ink colors, such as cyan, yellow and magenta. The black ink pen 
60 is illustrated herein as containing a pigment based ink. It is apparent 
that other types of inks may also be used in pens 60, 62, such as paraffin 
based inks, as well as hybrid or composite inks having both dye and 
pigment characteristics. 
The illustrated pens 60, 62 each include reservoirs for storing a supply of 
ink, and printheads 64, 66 respectively, for selectively ejecting the ink. 
While the black and color pens may be of different sizes, in the 
illustrated embodiment, the pens 60, 62 are of substantially the same 
size. The monochrome black pen 60 has a single reservoir 70 containing 
black ink, whereas the full color pen 62 has three reservoirs 72, 74 and 
76 for carrying the cyan, magenta and yellow inks (see FIG. 2). The black 
printhead 64 is in fluid communication with the black reservoir 70. The 
full color printhead 66 has three sets of nozzles, with each set in fluid 
communication with an associated one of the reservoirs 72, 74, 76. 
Each printhead 64, 66 has an orifice plate with a plurality of nozzles 
formed therethrough in a manner well known to those skilled in the art. 
The illustrated printheads 64, 66 are thermal inkjet printheads, although 
other types of printheads may be used, such as piezoelectric printheads. 
The printheads 64, 66 typically include substrate layer having a plurality 
of resistors which are associated with the nozzles. Upon energizing a 
selected resistor, a bubble of gas is formed to eject a droplet of ink 
from the nozzle and onto sheet 34 in the print zone 25. Ink may also be 
ejected into a spittoon portion of the service station 52 during 
servicing, or to clear plugged nozzles. The printhead resistors are 
selectively energized in response to firing command control signals 
delivered by a multi-conductor strip 68 from the controller 45 to the 
printhead carriage 50. 
Imaging Cartridge System 
FIG. 2 shows the printhead carriage 50 holding the color pen 62 and an 
imaging cartridge 80, retrofitted in place of the black ink cartridge 60. 
Of course, some printing mechanisms may be constructed to receive only the 
color pen 62 and the imaging cartridge 80, without the interchangeability 
feature. In the illustrated embodiment, the imaging cartridge 80 comprises 
a tri-compartment foam-filled cartridge having three ink-containing 
chambers or reservoirs 82, 84, 86, which may be of the same general 
construction as the full color cartridge 62. The imaging cartridge 80 has 
a printhead 88, which may be constructed as described above for printhead 
64 to include three nozzle sets, each in fluid communication with an 
associated reservoir 82, 84, 86. 
In contrast with the full color pen 62, the imaging cartridge 80 is a 
reduced colorant concentration cartridge. While the imaging cartridge 
reservoirs 82, 84, 86 preferably have the same amount of solvent or 
carrier as pen 62, the amount of colorant in each chamber is less than the 
amount of colorant in the color pen chambers 72, 74, 76. Since the 
illustrated color inks for pens 62 and 80 is a dye-based ink formulation, 
this colorant concentration may be also referred to by those skilled in 
the art as the "colorant concentration" of the pen. The black ink 
contained within pen 70 is illustrated as a pigment-based ink, which may 
also be reduced in colorant concentration by maintaining the same amount 
of solvent or carrier for a given pen capacity while reducing the amount 
of pigment in the concentration. For instance, the first imaging reservoir 
82 may contain only 10-30% of the full colorant concentration of cyan in 
chamber 72, while the second imaging reservoir 84 contains only 10-30% of 
the normal colorant concentration of magenta in chamber 74. 
The third imaging cartridge chamber 86 may carry either a full or a reduced 
colorant concentration of black ink, that is, either a 100% colorant 
concentration, or 3-15%, for instance, of the colorant concentration in 
the black reservoir 70. While a full colorant concentration of black ink 
in the imaging cartridge 80 is advantageous for printing clear, crisp 
black text, the reduced colorant concentration black provides better, 
photographic-type images. Note that the colors of cyan and magenta have 
been chosen for reduced colorant concentrations in the imaging pen 80, 
rather than yellow. This is because visually, yellow is a low contrast 
color, and any graininess of the yellow ink is not visually detectable to 
the human eye. Therefore, in many implementations, there is no need for a 
reduced colorant concentration of yellow ink. Yet, in other embodiments, 
the third chamber may contain an ink formulation of either a reduced or 
full concentration of yellow colored ink. For instance, a reduced yellow 
concentration may enhance transition regions in areas of flesh tones. 
However, use of the reduced colorant concentration imaging pen 80 without 
yellow has been found to significantly enhance the visual appearance of 
light tones and mid-tones in photographic type images, particularly when 
compared to the earlier dual pen printers, which had only a full colorant 
concentration tri-color pen and a black pen. 
For the printer 20 and controller 45 to distinguish whether the black pen 
60 or the imaging pen 80 is installed in carriage 50, the black and 
imaging pens 60, 80 each include an identification scheme. For instance, 
the pens 60, 80 may each include a unique identifier for automatic 
recognition by the system, such as a distinct binary code and/or resistors 
of different resistances. These identifiers are decodeable by the software 
or firmware of the printer controller 45, and/or the software of a printer 
driver, located in a host computer or device which communicates with 
printer 20. One suitable identification scheme for interchangeable 
printheads is disclosed in U.S. Pat. No. 4,872,027, also assigned to the 
present assignee, Hewlett-Packard Company. Alternatively, an operator may 
indicate which cartridge is installed, by making an appropriate entry into 
a host computer or by merely pressing a button on the keypad 46. Upon 
communication of which of the interchangeable pens 60 or 80 is located in 
carriage 50, the software driver within the host computer or printer then 
uses an appropriate rendering scheme suitable to which ever pen is 
installed. The printer controller 45 then employs suitable print modes and 
control parameters to generate firing signals that are communicated via 
strip 68 through the carriage 50 to properly fire either the black pen 60 
or the imaging cartridge 80. 
Retrofitting the carriage 50 with the imaging cartridge 80, instead of the 
black ink cartridge 60 advantageously allows for achieving 
near-photographic image print quality. This retrofit capability may be 
desirable to some consumers who want a dual personality printer. For 
example, many consumers typically print text or simple business graphics, 
in which case a dual pen printer having only black and full color pens 60, 
62 provides faster print speed and crisper black text. Yet these same 
consumers sometimes want to upgrade to their hardcopy output to have 
near-photographic image quality, which may be accomplished using the 
imaging cartridge 80. In the illustrated embodiment, using the imaging 
cartridge 80 and the full color cartridge 60 in carriage 50 allows the 
carriage to carry six reservoirs holding six varying colorant 
concentrations of different colors and intensities, as compared to the 
earlier printers which had a total of only four chambers carrying a 
maximum of four different colors. 
FIG. 3 illustrates an alternate embodiment of a superior imaging system 
configuration constructed in accordance with the present invention. The 
imaging system illustrated in FIG. 3 has a printhead carriage 50' which is 
substantially of the same construction as carriage 50, but longer in the 
direction of scanning axis 51, to accommodate a black ink cartridge 60'. 
The black pen 60' is of slightly reduced width from that shown for the 
black ink cartridge 60 in FIG. 1. In FIG. 3, the longer carriage 50' is 
shown with levers, latches or lid members 90, 92 and 94 in an open 
condition to show placement of the respective color, imaging and black 
pens 62, 80 and 60'. Similarly in FIG. 2, the retrofitted carriage 50 is 
shown with two cartridge-securing levers, latch or lid mechanisms 96, 98 
in an open position, rather than closed as shown in FIG. 1. 
In this tri-cartridge embodiment, the carriage 50' carries seven 
reservoirs, with three reservoirs carrying full colorant concentrations of 
cyan, magenta and yellow for the full color pen 62, reduced colorant 
concentrations of cyan, magenta and black for the imaging cartridge 80, 
and a full black colorant concentration for the black pen 60'. 
Alternatively, the imaging cartridge may contain reduced colorant 
concentrations of cyan, magenta and yellow if desired for some special 
imaging uses, such as for the extensive printing of portraits having a 
need for smoother blending of flesh tones. Use of the narrower black pen 
60' (that is, narrower than pen 60 in FIG. 1, which is substantially the 
same width as the tri-compartment pen 80) advantageously allows for a 
smaller width or "footprint" for printer 20. The term "footprint" refers 
to the amount of work space required to physically receive the printer 20, 
which can be an important consideration for some consumers. It is 
apparent, however, that the carriage 50' may also be made longer to 
accommodate a wider black pen, such as pen 60 shown in FIG. 1. While FIG. 
2 illustrates a black pen 60 which is of the same width as the imaging 
cartridge 80, it is also apparent that a reduced width pen, such as pen 
60', may be used instead of pen 60, by modifying the carriage 50 to 
interchangeably receive either a wide or a narrow cartridge. One example 
of such a system for interchangeably accommodating narrow and wider pens 
is disclosed in U.S. Pat. No. 5,208,610, assigned to the present assignee 
Hewlett-Packard Company. The imaging system shown in FIG. 3 is preferably 
more suitable for a permanent installation, whereas that of FIG. 2 may be 
more suitable for a retrofit or upgrade situation, or in some 
implementations for a permanent system. 
The imaging systems described above with respect to FIGS. 2 and 3 may be 
modified to accomplish a variety of different objectives. For instance, 
the drop volumes may be varied, particularly for the reduced colorant 
concentration printheads to achieve cost improvement. For instance, by 
reducing the drop volume, less ink is used, which reduces the cost per 
page printed. While the imaging pen 80 has been illustrated as a 
tri-chamber cartridge, it is apparent that these concepts may be extended 
to other multi-chamber pens, such as a quad-chamber pen having four 
chambers. This may be a particularly suitable arrangement for some 
implementations, such as: a quad-chamber imaging pen containing reduced 
colorant concentrations of cyan, magenta and yellow, with a full 
concentration of true black; or a quad-chamber imaging pen containing 
reduced colorant concentrations of cyan and magenta, a gray color (reduced 
concentration of black colorant), and a full concentration of true black. 
It may also be useful to include a multi-chamber cartridge having ink 
formulations of "primary" colors, such as red, green and blue, either at 
full or reduced colorant concentrations. Such a primary color pen in 
combination with the traditional cyan, magenta, yellow pen may result in 
ink savings over the systems described with respect to FIGS. 2 and 3, 
above. 
As another variation, the three-pen carriage 50' shown in FIG. 3 may be 
modified to carry three tri-chamber pens for a total of nine printheads 
and inks. In such an embodiment, a third tri-chamber pen 80' may carry a 
variety of different combinations of ink formulations, such as, the 
primary colors (red, green and blue). This third tri-chamber pen 80' may 
also be a second full color cartridge, or of another concentration of a 
reduced dye load. For instance, such a three tri-chamber pen carriage may 
carry one full color pen 62, and two imaging pens 80 and 80', with one 
carrying ink formulations having a 10% colorant concentration, and the 
other having a 40% concentration. It is apparent that a variety of 
different combinations of colors and concentrations may be used in the ink 
formulations of the imaging cartridge 80, 80'. 
The following Tables 1 and 2 list a variety of different interchangeable 
pen and ink formulation combinations, which may be implemented using the 
concepts described above to provide a dual (or multiple) personality 
printer, capable of producing a variety of different types of output, each 
with outstanding print quality. 
TABLE 1 
______________________________________ 
Two Pen Carriage Ink Formulation Combinations 
Interchangeable Carriage Position 
Other Position 
Options 
First Cartridge 
Second Cartridge 
Third Cartridge 
______________________________________ 
Business 
True Black Partial C, M & Gray 
Full C, M, Y 
Imaging 1 
-- Partial C, M & True Black 
Full C, M, Y 
Imaging 2 
-- Partial C, M, Y Full C, M, Y 
Imaging 3 
-- Partial R, G, B Full C, M, Y 
Imaging 4 
-- Full R, G, B Full C, M, Y 
Imaging 5 
-- Gray Full C, M, Y 
Imaging 6 
-- Partial C, M, Y & True 
Full C, M, Y 
Black 
Imaging 7 
-- Partial C, M, Gray & True 
Full C, M, Y 
Black 
______________________________________ 
TABLE 2 
______________________________________ 
Three Pen Carriage Ink Formulation Combinations 
Interchangeable Carriage 
Other Other 
Position Position Position 
First Second Third Fourth 
Options Cartridge 
Cartridge Cartridge 
Cartridge 
______________________________________ 
Business & 
Partial -- Full C, M, Y 
True Black 
Imaging C, M, 
Gray 
Imaging 8 
-- Partial C, M, Y 
Full C, M, Y 
True Black 
Imaging 9 
-- Full C, M, Y 
Full C, M, Y 
True Black 
Imaging 10 
-- Partial R, G, B 
Full C, M, Y 
True Black 
Imaging 11 
-- Full R, G, B 
Full C, M, Y 
True Black 
Imaging 12 
-- Gray Full C, M, Y 
True Black 
Imaging 13 
-- Partial First % 
Partial Second 
True Black 
Colorant % Colorant 
Imaging 14 
-- Partial First % 
Partial Second 
Full 
Colorant % Colorant 
C, M, Y 
______________________________________ 
Advantages 
The imaging cartridge system described above with respect to FIGS. 2 and 3, 
as well as the embodiments illustrated in Table 1, advantageously allows 
previously developed pen architecture to be used, for instance, the 
imaging cartridge 80 may be constructed in substantially the same fashion 
as the tri-compartment full color pen 62. This is particularly 
advantageous because existing drop volumes and other parameters may be 
used, albeit with a reduced colorant concentration content for the imaging 
pen 80. Using an existing pen architecture provides for very minor ink 
changes, that is no new formulations, only a lower concentration of dye or 
pigment in the imaging cartridge 80. Using existing pen architectures 
allows production of economical printing mechanisms, at a more attractive 
price for consumers than if totally new architectures where required. 
Thus, use of the illustrated embodiment leverages off of existing 
technology which is proven and accepted in the industry, while providing 
significant image quality improvements. 
Moreover, use of the interchangeable imaging cartridge system proposed 
herein provides imaging capability for those consumers wishing to pay for 
it initially, while providing a dual pen (four ink chamber) system for 
those consumers who primarily print black text or simple plain paper 
graphics. This system also accommodates those consumers who may initially 
have no need for, or not wish to invest in, an imaging system, but desire 
to have the ability to upgrade in the future. The ability to convert from 
an imaging print mode, using cartridge 80, back to the black and 
full-color cartridges 60, 62 facilitates faster black text printing (i.e., 
higher "throughput," which is typically measured in pages per minute). 
Using the dedicated black ink cartridge 60, particularly when filled with 
pigment-based ink, provides a crisper, sharper black when using plain 
paper (i.e., paper which has no special coating or treatment for enhanced 
compatibility with any particular type of ink). 
As a further advantage, the print quality achieved during trial runs of the 
illustrated imaging cartridge system yielded near-continuous tone images 
using the inkjet printer 20. Indeed, these near-continuous tone images 
provided by printer 20 where achieved using a variety of different types 
of print media, including specially coated paper, bond paper and plain 
paper. 
Use of the imaging cartridge system of the present invention also provides 
for a faster printed image, as compared to binary printers of equal print 
quality. This is because the imaging system described herein requires less 
data to achieve near-photographic quality images, than the data required 
for earlier high resolution binary printers. This faster image rendering 
can enhance the throughput of the printer, that is, the rating of printer 
speed in pages per minute. 
Furthermore, the superior images which are achievable using the imaging 
cartridge system described herein are provided at a lower addressability 
than traditional "binary" inkjet printing. For example, the visual 
equivalent of a 1200 dpi (dots-per-inch) rated image printed with full 
colorant concentrations of black, cyan, yellow and magenta, can be 
accomplished using the imaging system described herein but at a lower 
rating of 300 dpi. This feature then places less stringent requirements on 
the mechanism accuracy, when compared to the earlier full colorant 
concentration 1200 dpi systems which had to place smaller dots at higher 
resolutions to achieve this high visual quality. Thus, using the imaging 
system described herein, superior images are achievable using a more 
economically designed printer product, with comparable specifications to 
currently-produced, low-cost, binary inkjet printers.