Note: Descriptions are shown in the official language in which they were submitted.
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INR SU~?PLY IDENTIFIC~TION SYSTEM
BACKGROUND OF T~IE INVENTION
This invention relates to an ink jet marking
system, and in particular, to improving the quality of the
printed image and increasing the reliability and
durability of the marking system by providing a means to
identify and monitor an ink supply such that the printing
function of the marking device can be controlled according
to the status of the ink supply.
The use of ink jet marking systems in facsimile
machines, wide format plotting, special marking
applications, and general printing is known. All of these
marking applications are subsequently referred to as
printing. This invention relates to ink jet printing in
general and, more specifically, to thermal ink jet
printing.
To ensure high quality and reliable thermal ink
jet printing, several variables within the operating
environment of the thermal ink jet printer must be
controlled. Probably the single most important aspect of
ink jet printing relates to the delivery of ink from an
ink supply through a print element onto a printing medium.
Consistent ink delivery requires that the formulation and
chemical composition of the ink be carefully matched to
the printhead or print element in order to achieve
reliable and predictable performance over time. The ink
must be correctly formulated in order to achieve high
quality printing. Appropriate ink formulations include:
certain necessary additives (often present in small
quantities), component chemicals of sufficient purity, and
sufficient filtration to eliminate any particulate matter.
Characteristics of high quality printing include dark text,
lines without ragged edges, the capability to create output
in a broad spectrum of colors, the ability to print on a
board range of paper types. Different paper types vary
widely according to the process used to make the paper
(e.g., an acid-based process), the origin of fibers in the
paper (i.e., the species of tree used to
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make the paper), the size level of the paper (i.e., the amount
of sizing added to the paper to give it water repellency), as
well as other aspects known to the paper making and paper marking
arts.
Marking process hard failure modes than can occur when the
incorrect ink formulation is used include kogation (i.e., when
deposits from the ink are burned on the print element),
burned out or damaged print elements, orifices or nozzles
plugged with ink particulate, and damage to print elements
caused by chemical attack. In addition, ink must be
present at the printhead to ensure that the printhead
heater elements are not overheated if they are fired
without ink being present. For applications in which the
printer operates in an unattended mode (e.g., facsimile
and plotter applications), the inadvertent depletion of
the ink supply results in an inconvenience. In some cases
when printing is attempted without ink being present,
information is lost and cannot be recovered. Therefore,
enabling the printer to detect an "out of ink" condition
and to react accordingly would be advantageous.
Ink jet printers in which the print element and
the ink supply are combined into a single replaceable "ink
jet cartridge" and ink jet printers in which the print
element and the ink supply or ink supplies are severable
are both known. This invention relates to both types of
printers, but is more specifically directed to printers
that contain a printhead that can be separated from the
ink supply. In this case, because the ink supply can be
changed without changing the printhead, the printhead will
typically be used with several ink supplies. In either
case, the quantity of ink contained within the ink supply
reflects the printing needs of a typical user, as well as
a balance between optimum printer performance (i.e.,
ensuring that fresh ink is used) and user convenience
(i.e., minimizing the frequency of ink supply changes).
In addition, the quantity of ink within the ink supply
must be sufficiently small so that the resulting mass of
the ink does not affect the operation of the printer
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carriage in scanning-type printer configurations. The
present invention also applies to an ink supply bag or
bottle that is used with a full width array print bar.
In principle, an empty ink supply container can be
S refilled and reused in a printer. In practice, the
original ink formulations which are contained in such ink
supplies are carefully optimized to meet the operating
requirements of a specific ink jet printhead and
associated marking hardware. The inks often contain a
number of proprietary ingredients. Consequently, ink jet
printer manufacturers typically sell replacement ink
supply containers but not refill kits. Aftermarket or
"third party" suppliers, however, often sell refill kits
or "clone" ink supply containers. In some cases, third
lS party refill kits contain inks that reduce printer
performance and decrease print element life, in part
because third parties do not optimize inks for specific
applications.
In addition, as ink jet resolution increases, the
fluid passageways within the printhead become smaller and
more susceptible to being plugged by ink borne particulate.
The sources of particulate contamination include
precipitates from the ink, ~sloughing~ or degradation of
the container materials and/or the container filling
process. Therefore, ink filtration and ink supply filling
conditions are important considerations in ensuring ink
integrity.
As a result of the continued development of ink
jet technology, printing speeds are increasing and ink
supplies must be changed more often. in addition,
manufacturers now produce permanent and semipermanent
printheads. Therefore, manufacturers seek to maintain
these printheads by controlling the quality of the ink
supplied to the printhead.
One approach to controlling the quality of the ink
is monitoring the ink supply utilization by identifying
each ink supply. Under this approach, ink supplies are
encoded with a designation that can be detected or
interpreted by a device attached to the printer.
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Accordingly, the printer can be configured so it can
function only if the detected ink supply carries a
recognized designation, e.g., a serial number.
From the standpoint of an ink supply or printer
manufacturer, an ink supply identification system provides
additional quality control assurances after the time of
sale of the printer. In the case of the printer
manufacturer, more information about what type and
quantity of ink that has been consumed by the printer can
be stored and made accessible to the manufacturer's
service personnel. if a manufacturer decides that a
particular type of ink should not be used in a certain
printer model, this model can be configured so as to not
recognize the designation for that particular type of ink.
Over time, this information will provide the manufacturer
with a better basis on which to estimate, e.g., warranty
and service costs. Because customers will frequently turn
off the power to the printer and unplug it, however, the
ink supply information must survive power down cycles. At
the same time, the cost of the identification system must
be aligned with the cost of the ink supply. In one
embodiment, the ink supply container itself is essentially
a plastic molded part that can be made for a few cents, so
the identification system must be implemented for nearly
the same cost.
Within the field of electrostatographic
reproducing machines (i.e., photocopiers), a
monitor/warranty system for copiers that distinguishes
between authorized, authorized but expired, and authorized
and unexpired replaceable cartridge units is known, as
disclosed in U.S. Patent No. 4,961,088 to Gilliland et al.
Each authorized cartridge includes a memory/identification
chip in the form of an EEPROM (Electrically Erasable
Programmable Read Only Memory) that connects to the copier
when the cartridge is installed. The EEPROM logs a count
of the number of images copied with that cartridge and
disables it when the predetermined maximum number of
images is reached. U.S. Patent No. 5,283,594 to Iwao
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discloses a color copier that detects which color of toner
is presently in use by interpreting the magnetic signal
emanating from a toner tank of that color.
The copier system, however, cannot be effectively
implemented for ink jet printers. Effective tracking of
ink usage in ink jet printers must take advantage of the
fact that ink jet printing is a digital marking process.
The controller in an ink jet printer produces a string of
binary commands that trigger individual pixel firing. In
order to keep track of the amount of ink that has been
used, it is necessary to both count the number of pixels
fired and account for ink used in maintenance cycles.
Such an approach is not possible in copier applications,
because the amount of toner transferred is dependent upon
only the integer number of images copied.
Within the field of printers, U.S. Patent No.
4,872,027 to Buskirk et al. discloses a printer having
identifiable and interchangeable heads. The printer
control changes according to the particular type of head
that has been installed as interpreted by the code on the
head. Each class of head, e.g., a graphics head or a text
head, carries a distinct code. Different codes are
interpreted by determining which of several selectively
connectable contact pads disposed on the head are
connected to the printer. Individual heads belonging to
the same class, however, are not distinguishable.
U.S. Patent No. 5,283,593 to Wehl discloses an ink
reservoir that prevents unauthorized refilling. The ink
reservoir includes a contact element that, upon being
moved to a certain position, triggers the printer to cease
functioning. The contact element is moved to this
position under the action of a collapsing outer surface of
the ink reservoir as ink is consumed. Once the contact
element reaches this position, it is held in place by
magnetic force, even if a refilling operation that expands
the collapsed outer surface of the ink supply is
attempted. Accordingly, each ink supply can be used only
once.
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A primary concern of users today is ensuring
reliable printer operation. In addition, users would
appreciate a feature by which the printer would signal the
impending expiration of the ink supply. Users would also
appreciate being prompted with maintenance information at
predetermined intervals based upon the volume of ink that
has been used. These considerations, as well as those of
ensuring high print quality and maintaining printer
reliability, can be addressed by providing individually
identifiable ink supplies.
At the same time, a manufacturer must be able to
guarantee its printer and print element. Such a guarantee
can only be offered when some assurance exists about the
quality of ink used in the printer. A manufacturer also
seeks to ensure reliability of its products and provide a
tamper-proof method by which compliance with operating
procedures, such as correct ink supply usage, can be
assessed.
SUMMARY OF THE INVENTION
It is an object of an aspect of this invention to
provide a system by which individual ink supplies can be
encoded with a unique designation that can be discerned by
a printer. This and other objects are achieved by
providing an apparatus and method for identifying
individual ink supplies.
Other aspects of this invention are as follows:
A printer having an ink supply identification system,
said ink supply system comprising:
an ink supply;
an ink supply identification corresponding to said ink
SupplYi
a print element connected to said ink supply and said
printer; and
control means for controlling an operation of said
printer in response to said ink supply identification.
A method of maintaining the reliability of a printer,
said printer having an ink supply identification system
that includes an ink supply, an ink supply identification
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corresponding to said ink supply, a print element and
control means, the method comprising the steps of:
connecting said print element to said printer; and
controlling an operation of said printer in accordance
with said ink supply identification.
By way of added explanation, an ink supply
identification system embodying the invention includes an
ink supply, an ink supply identification corresponding to
the ink supply, a print element connected to the printer,
and a controller resident in the printer. The controller
can include a recognition device for recognizing the ink
supply identification. The recognition device can
recognize a number of different signals, including e.g., a
signal indicating that the ink supply is authorized, a
signal indicating that the ink supply is depleted, and a
signal indicating that the ink supply is unauthorized. The
printer can be configured such that it continues to operate
only if a signal indicating that the ink supply is
authorized is received.
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The signal corresponding to the ink supply
identification and recognized by the recognition device can
emanate from the ink supply container or the print
cartridge. The ink supply identification can be, e.g., a
magnetic strip, a nonvolatile electronic device (e.g., an
EPROM chip), or a bar code that is affixed to the ink
supply container. In this case, the recognition device is
either a magnetic strip reader, a command sequence from the
printer controller, or a bar code reader, respectively.
Alternatively, the ink supply identification can be a
string of alpha numeric characters.
The print element and the ink supply container can
be disposed together in an ink supply cartridge. The ink
supply can also be permanently attached to the cartridge.
The printer and or the ink supply can also include
a memory. The memory can be provided with a number of
different nonvolatile registers, including, e.g., spent
ink supply, used ink supply, and authorized ink supply
registers. The memory can also be used to store a maximum
number of firing cycles for a particular print element, in
which case the printer also includes an ink quantity
detection device for detecting the quantity of ink
remaining in the ink supply. A method for practicing the
present invention is also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
A complete understanding of the present invention
may be obtained by reference to the accompanying drawings,
when considered in conjunction with the subsequent
detailed description thereof, in which:
Fig. 1 is an isometric view of a carriage-type
thermal ink jet printeri
Fig. 2 is a schematic view of the printer having
an ink supply cartridge identification system according to
a first embodiment; and
Fig. 3 is a schematic view of the printer having
an ink supply identification system according to a second
embodiment;
Fig. 4 is a flowchart depicting the operation of
one embodiment of the present invention;
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Fig. 5 is a flowchart depicting the operation of
the firing cycle count aspect of the present invention;
and
Fig. 6 is a diagram showing a flowchart of the
steps performed by the controller in one embodiment
superimposed on a schematic view of the ink supply
identification system.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to the drawings, and in particular to
Fig. 1, a thermal ink jet printer 10 is shown. Several
ink supply cartridges 2, each having an integrally
attached print element 54, are mounted on a reciprocating
carriage 6. During the printing mode, the carriage 6
translates back and forth on guide rails 7 as depicted by
the arrow 4. A recording medium 8, such as paper, is held
stationary while the carriage 6 is moving in one
direction. Before the carriage 6 moves in the reverse
direction, the recording medium 8 is stepped a distance
equal to the height of the swath of data being printed by
the print elements. Each print element 54 has a linear
array of nozzles that are aligned in a direction
perpendicular to the direction that the carriage is
translating. The nozzles face the recording medium and
expel ink droplets 9 toward the recording medium.
2 5 According to a first embodiment as shown in Fig.
2, the printer 10 is configured to include a nonvolatile
memory 2 0. The contents of the memory 20 remain in
storage even if the power to the printer 10 is turned off.
The memory 20 iS connected to the printer controller (CPU)
22. When the ink supply cartridge 2 is installed, it
becomes electrically connected by a series of connections
24 to the printer 10. The connections 24 serve to connect
the CPU 22 and memory 20 of the printer 10 to the print
element 54 of the ink supply cartridge 2. The connections
24 include a fusible link or other similar programmable
device that can be subjected to a current or voltage to
permanently alter a signal that can be read through the
connection 24. The fusible link can be, e.g., a narrow
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aluminum strip disposed over a polysilicon heater (not
shown) or, alternatively, an ~PROM memory location that
can be written in only one direction such as from 1 to 0
or 0 to l. The heater can be energized to fuse the fusible
link and in turn sever the electrical connection 24. In
the following paragraphs, the term fusible link will be
used to refer to the class of devices which can
permanently record an electrical event and not be
subsequently altered.
In a first embodiment, the ink supply
identification system includes a fusible link and an ink
supply having a serial number. The ink supply
identification system according to this embodiment is
inexpensive because the serial number can be a bar code,
magnetic strip or other economical method of recording a
digital code. Although the description below refers to
the configuration in which the serial number is on the ink
supply, the description also applies to the configuration
in which the ink supply and the print element are
consolidated to create a replaceable ink jet cartridge.
Each ink supply 26 is encoded with a unique serial
number or one of a large finite set of serial numbers. In
the case where there are a finite set of serial numbers
and multiple copies of each serial number exist within the
ink supply population, a sufficiently large set of serial
numbers must be used so that the probability of obtaining
the same number twice in one printer is very small
compared to other failure modes in the printer.
As shown in Figure 4, when the printer is turned
on or at the start of a job ~step S90), the printer
detects whether the fusible link of the attached ink
supply is blown (step S92) and reads the serial number of
the ink supply (step S91). Preferably, the fusible link
is integrated with other control circuitry functions so
that the electrical connection cannot be tampered with or
disabled without also making the printer nonfunctional.
If the fusible link is blown, the ink supply has been
previously used. If the ink supply has been previously
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used, the printer compares the ink supply serial number
with the serial numbers already stored in memory (step
S93). The printer must match the ink supply serial number
to an existing serial number within the printer memory in
order to enable printing. If no match is found, the
printing function is disabled (step S101). If a match is
found, the printer checks the remaining ink supply and
verifies that ink is left in the supply.
The printer detects the quantity of ink remaining
in the ink supply (step S94). If the quantity remaining
is less than a predetermined quantity, the operation of
the printer ceases (step S103). If the printer determines
that the quantity remaining is greater than or equal to
the predetermined quantity (step S96), the printer
determines whether the quantity remaining is within a
predetermined range of the predetermined quantity (i.e.,
whether the ink supply, although not fully depleted, is
close to being fully depleted) (step S98). If the
quantity remaining is within the predetermined range, a
warning to that effect is displayed (step 102). In either
case, printing of the job then begins (step S100).
If the fusible link is not blown, the printer
records the first usage of the ink supply by blowing the
fuse, reads and records the serial number (step S95), and
initializes ink usage recording for that supply (step
S99). The printer can optionally check for a blown fuse
condition to assure that the first usage is recorded (step
S97) before initializing ink usage recording.
Periodically, as printing is taking place, the nonvolatile
memory that stores the amount of ink is read and updated
according to the amount of ink used since the last update.
These updates should occur frequently to prevent rounding
errors from short jobs. The ink supply identification
system allows multiple partially used cartridges to be
inserted and removed from a printer, but does not allow
two printers to share the same cartridge.
Although the memory 20 in Fig. 2 is shown as part
of the printer, the memory 20 can also be configured as a
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component of the ink supply cartridge 2. The memory 20 can
be included in the control circuitry (not shown) within
the print element 54 by using, e.g., polysilicon/pyrolytic
nitride/tantalum as a floating gate erasable transistor
device. Alternatively, a second EPROM device can be
disposed in the print element to serve as the memory 20.
An embodiment of the present invention in which
the memory 20 is configured as a component of the ink
supply 26 is shown in Fig. 6. The print element 54 and the
ink supply 26 are shown schematically in relation to the
CPU 22 of the printer 10. Although the print element and
ink supply are described below as being severable, the
dashed line separating the print element 54 from the ink
supply 26 indicates that this embodiment applies to
applications using an ink jet cartridge as well. During
normal printing, data representing the image to be output
is transmitted from the CPU 22 to the ink supply cartridge
(S901). These data are a series of "ls" and "0s" that
indicate whether or not, respectively, an ink jet of the
print element is to be fired to produce a printed pixel at
a particular location. At an appropriate interval, a
counter is incremented (step S902). In step S903, the
count registered in the counter is compared to a
predetermined count. The predetermined count is set to a
high number of printed pixels according to the particular
application, such that the steps described below are
executed one or more times during the printing of each
page. If the count is less than the predetermined count,
the CPU 22 continues to transmit data to the print element
54 and printing continues.
If the count is greater than the predetermined count,
the CPU 22 initiates an ink supply write protocol (step
S904). In step S904, the CPU 22 initiates a communication
protocol with the ink supply 26, the CPU 22 validates the
ink supply 26 as being authorized, and then communicates
that the CPU 22 is writing to the memory 20 in the ink
supply 26. In step S905, the controller erases a " 1 "
from the memory 20 to represent that a specified quantity
of ink has been
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depleted from the ink supply 26. The specified quantity
of ink is equal to the total capacity of the ink supply 26
divided by the number of "ls" stored in the memory 20.
According to this routine, the current volume of ink in
5 the ink supply is decreased according to the number of
pixels printed (each pixel being equivalent to one drop of
ink) based upon the number of "ls" in the memory.
Fig. 6 also shows the steps performed by the CPU
22 in executing a page advance and/or maintenance routine
(step S906). The page advance and/or maintenance routine
is performed each time the printer is turned on and at the
beginning of each job, as well as at other appropriate
intervals. In contrast to the steps described directly
above, the page advance and/or maintenance routine is
15 preferably executed when the printer is not printing data
so as to take advantage of the full computing power of the
CPU 22. In step S907, the CPU determines if an ink supply
read protocol should be performed by detecting whether the
ink supply is authorized. If the ink supply is not
20 authorized, the printer ceases operation. Similar to the
ink supply write protocol described above in connection
with step S904, if the CPU 22 recognizes the ink supply 26
as being authorized, the CPU 22 then reads the contents of
the memory 20 that represent the quantity of the remaining
25 ink (step S908). Based on the data read from the memory
20, the CPU 22 determines whether the memory 20 contains
any "ls" (i.e., whether any ink remains within the ink
supply 26) (step S905) . If at least a single "l" is
present, the CPU 22 determines the exact quantity of ink
(step S912), stores this value and enables printing to
occur (step S913).
If, on the other hand, at least a single "1" is
not present in the memory 20 (step S910), the printer
enters an alternative operating mode (step S911) because
35 the CPU 22 determines that the ink supply is depleted. In
the alternative operating mode, the CPU 22 preferably
issues a warning to the effect that printing is halted
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until the current depleted or unauthorized ink supply is
replaced.
In addition to detecting whether a fresh ink
supply cartridge can be used with the particular printer,
the CPU 22 also determines the number of firing cycles
that the currently installed ink supply cartridge has
completed. In a preferred embodiment, the number of drops
or other appropriate measure of consumed ink is rounded
off to suit the particular operating requirements. As
shown in Fig. 5, after the printing cycle begins (step
S80), the CPU 22 periodically updates the firing cycle
count (step S82), stores it in the memory 20 (step S84),
and compares it to a predetermined maximum firing cycle
count (step S86). As the firing cycle count approaches
the maximum firing cycle count, the CPU 22 optionally
transmits a signal to a display (not shown) or other
similar device to signal the user that a fresh ink supply
will soon be required. Once the firing cycle count
reaches the maximum firing cycle count, the CPU 22
disables the printer,
According to a second embodiment as shown in Fig.
3, the ink supply 26 is separately detachable from either
the print element 54 or the print element 54 and printer
combination. In Fig. 3, the print element 54 is
included as a removable component of the printer. In this
embodiment, the ink supply 26 is encoded with a serial
number. The serial number of the ink supply 26 can be
encoded, e.g., by (i) affixing a magnetic strip to the ink
supply container, (ii) affixing a bar code or other
optically recognizable symbol to the ink supply container,
or (iii) providing a circuit or chip within the ink supply
that establishes an electrical connection with the print
element 54 and printer 10 circuity, etc. In the first and
second cases of an ink supply having a magnetic strip or a
bar code, the CPU 22 receives a detection signal from a
magnetic strip reader or a bar code reader (not shown),
respectively, when the ink supply is installed. This
embodiment permits the manufacturer to account for the
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distinct usable lives of the ink supply and the print
element. In other words, the CPU can signal the user that
the currently installed ink supply has been used up, e.g.,
used six times, while the currently installed print
element has not yet reached the maximum firing cycle
count, e.g., the equivalent of firing the ink contained in
ten ink supplies.
The ink supply of this embodiment could also be
configured to provide the user with an indication of the
ink supply fill level. In this case, the CPU 22 compares
the current ink supply fill level to a known level stored
in the memory 20 to determine whether the ink supply is
depleted. The user receives a signal from the CPU 22 that
the ink supply is nearly depleted so that a fresh ink
supply can be substituted before a new print job is
initiated. When a fresh ink supply is installed, the CPU
22 resets the current ink supply level. Additionally, the
CPU 22 prevents the user from operating the printer when a
spent ink supply has been installed.
In a third embodiment, the additional circuitry
required to implement either the first or the second
embodiment is included in the print element 54, either as
an integral part of its circuitry or as separate
components. In other words, print elements containing a
memory could be retrofitted for conventional print
elements in conventional printers that use either an ink
supply cartridge or a separately connectable ink supply.
Installing a print element having the additional circuitry
establishes the connection between the CPU 22 of the
conventional printer and the print element 54.
With respect to each of the embodiments, the
contents of the memory 20 can be configured in several
ways. First, the memory 20 can include a register of the
serial numbers for each print element 54 that has been
used in the printer 10 (i.e., the "used" register). In
this case, the CPU 22 compares the detected serial number
to the serial numbers in the used register and permits the
printer to continue operating only if the detected serial
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number matches a number within the used register and if
the ink supply of the print element is not depleted. In
this case, the print elements having serial numbers that
appear within the used register are considered to be
unauthorized when their ink supplies are depleted.
Second, the memory 20 can include a register of
authorized numbers (i.e., the "authorized" register).
Several serial numbers or ranges of serial numbers are
prerecorded in the authorized register by the
manufacturer. These authorized serial numbers can be the
appropriate types of print elements and ink supply
cartridges for a particular printer model. In other
words, the manufacturer can ensure that an ink supply
cartridge that has a normal physical appearance, but that
is otherwise unsuitable for the particular printer, will
cause the printer to become disabled if the ink supply
cartridge is installed. In this way, the manufacturer can
take steps to avoid damage to the printer and prevent the
user from inserting improper ink supply cartridges.
Third, the memory can include a register that
contains the serial numbers of print elements that have
been used more than a recommended number of times (i.e.,
the "spent" register). Thus, the printer can accept any
one of several recognized cartridges that were previously
used but not depleted. The spent register contains a
counter value for each of the serial numbers contained
within a first register. Each time a serial number is
detected, the count associated with that serial number is
incremented. When the count for a particular print
element reaches the recommended number, the CPU 22
transfers the serial number for that print element from
the first register to the spent register. A subsequent
attempt to use the print element disables the printer.
The various ways of configuring the memory can be
combined. For instance, the memory may include both an
authorized register and a used register. Furthermore,
although the preceding discussion refers to serial
numbers, it is understood that this term encompasses
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whatever unique indicia is used to designate each
independent ink supply cartridge or ink supply.
Since other modifications and changes varied to
fit particular operating requirements will be apparent to
those skilled in the art, the invention is not considered
to be limited to the example chosen for the purpose of
disclosure, and thus, the invention encompasses all
changes and modifications that do not constitute a
departure from its true spirit and scope.
