Title of Invention

AN INKJET PRINTING SYSTEM

Abstract The present disclosure relates to an inkjet printing system (10) that includes an inkjet printhead (24) having a plurality of electrical contacts (26). The plurality of electrical contacts (26) include address contacts and enable contacts for enabling drop generators (42) and drive current contacts for providing drive current to enable drop generators (42) for selectively ejecting ink therefrom. The printing system (10) includes a printing device having a plurality of electrical contacts (26) including address contacts, enable contacts and drive current contacts. The plurality of electrical contacts (26) are configured to establish electrical contact with corresponding electrical contacts (26) on the inkjet printhead (24) upon insertion of the inkjet printhead (24) into the printing device. The printing device provides periodic address signals (A1-13) and enable signals (E1-2) to the address and enable contacts one the printhead (24). In addition, the printing device selectively applies drive current to accomplish forming images on print media (22).
Full Text

AN INKJET PRINTING SYSTEM
BACKGROUND OF THE INVENTION
This invention relates to inkjet printing devices, and more particularly to an
inkjet printing device that includes a printhead portion that receives drop activation
signals for selectively ejecting ink.
Inkjet printing systems frequently make use of an inkjet printhead mounted to
a carriage which is moved back and forth across print media such as paper. As the
printhead is moved across the print media, a control device selectively activates each
of a plurality of drop generators within the printhead to eject or deposit ink droplets
onto the print media to form images and text characters. An ink supply that is either
carried with the printhead or remote from the printhead provides ink for replenishing
the plurality of drop generators.
Individual drop generators are selectively activated by the use of an activation
signal that is provided by the printing system to the printhead. In the case of thermal
inkjet printing, each drop generator is activated by passing an electric current through
a resistive element such as a resistor. In response to the electric current the resistor
produces heat, that in turn, heats ink in a vaporization chamber adjacent the resistor.
Once the ink reaches vaporization, a rapidly expanding vapor front forces ink within
the vaporization chamber through an adjacent orifice or nozzle. Ink droplets ejected
from the nozzles are deposited on print media to accomplish printing.
The electric current is frequently provided to individual resistors or drop
generators by a switching device such as a field effect transistor (FET). The
switching device is activated by a control signal that is provided to the control
terminal of the switching device. Once activated the switching device enables the
electric current to pass to the selected resistor. The electric current or drive current
provided to each resistor is sometimes referred to as a drive current signal. The
control signal for selectively activating the switching device associated with each
resistor is sometimes referred to as an address signal.
In one previously used arrangement, a switching transistor is connected in
series with each resistor. When active, the switching transistor allows a drive current

to pass through each of the resistor and switching transistor. The resistor and
switching transistor together form a drop generator. A plurality of these drop
generators are then arranged in a logical two-dimensional array of drop generators
having rows and columns. Each column of drop generators in the array are connected
to a different source of drive current and with each drop generator within each column
connected in a parallel connection between the source of drive current for mat
column. Each row of drop generators within the array is connected to a different
address signal with each drop generator within each row connected to a common
source of address signals for that row of drop generators. In this manner, any
individual drop generator within the two-dimensional array of drop generators can be
individually activated by activating the address signal corresponding to the drop
generator of row and providing drive current from the source of drive current
associated with the drop generator column. In this manner, the number of electrical
interconnects required for the printhead is greatly reduced over providing drive and
control signals for each individual drop generator associated with the printhead.
While the row and column addressing scheme previously discussed is capable
of being implemented in relatively simple and relatively inexpensive technology
tending to reduce printhead manufacturing costs, this technique suffers from the
disadvantage of requiring relatively large number of bond pads for printheads having
large numbers of drop generators. For printheads having in excess of three hundred
drop generators, a number of bond pads tends to become a limiting factor when
attempting to minimize the die size.
Another technique that has been previously been used makes use of
transferring activation information to the printhead in a serial format. This drop
generator activation information is rearranged using shift registers so that the proper
drop generators can be activated. This technique, while greatly reducing the number
of electrical interconnects, tends to require various logic functions as well as static
memory elements. Printheads having various logic functions and memory elements
require suitable technologies such as CMOS technology and tend to require a constant
power supply. Printheads formed using CMOS technology, which tend to be more
costly to manufacturer than printheads using NMOS technology. The CMOS

manufacturing process is a more complex manufacturing process than the NMOS
manufacturing process that requires more masking steps that tend to increase the costs
of the printhead. In addition, the requirement of a constant power supply tends to
increase the cost of the printing device that must supply this constant power supply
voltage to the printhead.
There is an ever present need for inkjet printheads that have fewer electrical
interconnects between the printhead and the printing device thereby tending to reduce
the overall costs of the printing system as well as the printhead itself. These
printheads should be capable of being manufactured using a relatively inexpensive
manufacturing technology that allows the printheads to be manufactured using high
volume manufacturing techniques and have relatively low manufacturing costs.
These printheads should allow information to be transferred between the printing
device and the printhead in a reliable manner thereby allowing high print quality as
well as reliable operation. Finally, these printheads should be capable of supporting
large numbers of drop generators to provide printing systems mat are capable of
providing high print rates.
SUMMARY OF THE INVENTION
One aspect of the present invention is an inkjet printing system that includes
an inkjet printhead having a plurality of electrical contacts. The plurality of electrical
contacts include address contacts and enable contacts for enabling drop generators
and drive current contacts for providing drive current to enable drop generators for
selectively ejecting ink therefrom. The printing system includes a printing device
having a plurality of electrical contacts including address contacts, enable contacts
and drive current contacts. The plurality of electrical contacts are configured to
establish electrical contact with corresponding electrical contacts on the inkjet
printhead upon insertion of the inkjet printhead into the printing device. The printing
device provides periodic address signals and enable signals to the address and enable
contacts one the printhead. In addition, the printing device selectively applies drive
current to accomplish forming images on print media.
Another aspect of the present invention is an inkjet printhead responsive to
enable and drive current signals for dispensing ink. The inkjet printhead includes an

energy storage device for storing energy. Also included is an energy charging device
responsive to a first enable signal for storing energy in the energy storage device. The
inkjet printhead further includes an energy discharging device responsive to a second
enable signal for discharging energy in the energy storage device. A drop generating
device is included for dispensing ink from the inkjet printhead upon activation. The
drop generating device is activated by a drive current signal active and energy stored
in the energy storage device being greater than a threshold energy level.
Yet another aspect of the present invention is an inkjet printhead having a
plurality of drop generators with each drop generator of the plurality of drop
generators responsive to an activation signal and a drive current for selectively
dispensing ink therefrom. The inkjet printhead includes a plurality of groups of drop
generators for depositing ink on media. Each of the plurality of groups of drop
generators are capable of activation once over a printhead activation cycle. The
printhead activation cycle is subdivided into a plurality of timeslots with each of the
plurality of groups of drop generators having a corresponding timeslot associated
therewith. The activation signal is active in the corresponding timeslot before drive
current is provided. In addition, the activation signal is active for a duration that is
less than a duration drive current is provided. Each drop generator within each group
of drop generators is configured so that when activated the drop generator is active for
the duration that drive current is provided,
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 depicts a printing system of the present invention that incorporates an
inkjet print cartridge of the present invention for accomplishing printing on print
media shown in a top perspective view.
Fig. 2 depicts the inkjet print cartridge shown in Fig. 1 in isolation and viewed
from a bottom perspective view.
Fig. 3 is a simplified block diagram of the printing system shown in Fig. 1 that
includes a printer portion and a printhead portion.
Fig. 4 is a block diagram showing further detail of one preferred embodiment
of a print control device associated with the printer portion and the printhead shown
with 16 groups of drop generators.

Fig. 5 is a block diagram showing further detail of one group of drop
generators having 26 individual drop generators.
Fig. 6 is a schematic diagram showing further detail of one preferred
embodiment of one individual drop generator of the present invention.
Fig. 7 is a schematic diagram showing two individual drop generators for the
printhead of the present invention shown in Fig. 5.
Fig. 8 is a timing diagram for operating the printhead of the present invention
shown in Fig. 4.
Fig. 9 is an alternative timing diagram for operating the printhead of the
present invention shown in Fig. 4.
Fig. 10 is a detailed view of the timing for timeslots 1 and 2 of the timing
diagram shown in Fig. 8.
Fig. 11 is a detailed view of the timing for timeslots 1 and 2 of the alternative
timing diagram shown in Fig. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Fig. 1 is a perspective view of one exemplary embodiment of an inkjet
printing system 10 of the present invention shown with its cover open. The inkjet
printing system 10 includes a printer portion 12 having at least one print cartridge 14
and 16 installed in a scanning carriage 18. The printing portion 12 includes a media
tray 20 for receiving media 22. As the print media 22 is stepped through a print zone,
the scanning carriage 18 moves the print cartridges 14 and 16 across the print media.
The printer portion 12 selectively activates drop generators within a printhead portion
(not shown) associated with each of the print cartridges 14 and 16 to deposit ink on
the print media to thereby accomplish printing.
An important aspect of the present invention is a method for which the printer
portion 12 transfers drop generator activation information to the print cartridges 14
and 16. This drop generator activation information is used by the printhead portion to
activate drop generators as the print cartridges 14 and 16 are moved relative to the
print media. Another aspect of the present invention is the printhead portion that
makes use of the information provided by the printer portion 12. The method and
apparatus of me present invention allows information to be passed between the printer

portion 12 and the printhead with relatively few interconnects thereby tending to
reduce the size of the printhead. In addition the method and apparatus of the present
invention allows the printhead to be implemented without requiring clocked storage
elements or complex logic functions thereby reducing the manufacturing costs of the
printhead. The method and apparatus of the present invention will be discussed in
more detail with respect to Figs. 3-11.
Fig. 2 depicts a bottom perspective view of one preferred embodiment of the
print cartridge 14 shown in Fig. 1. In the preferred embodiment, the cartridge 14 is a
3 color cartridge containing cyan, magenta, and yellow inks. In this preferred
embodiment, a separate print cartridge 16 is provided for black ink. The present
invention will herein be described with respect to this preferred embodiment by way
of example only. There are numerous other configurations in which the method and
apparatus of the present invention is also suitable. For example, the present invention
is also suited to configurations wherein the printing system contains separate print
cartridges for each color of ink used in printing. Alternatively, the present invention
is applicable to printing systems wherein more than 4 ink colors are used such as in
high-fidelity printing wherein 6 or more ink colors are used. Finally, the present
invention is applicable to various types of print cartridges such as print cartridges
which include an ink reservoir as shown in Fig. 2, or for print cartridges which are
replenished with ink from a remote source of ink, either continuously or
intermittently.
The ink cartridge 14 shown in Fig. 2 includes a printhead portion 24 that is
responsive to activation signals from the printing system 12 for selectively depositing
ink on media 22. In the preferred embodiment, the printhead 24 is defined on a
substrate such as silicon. The printhead 24 is mounted to a cartridge body 25. The
print cartridge 14 includes a plurality of electrical contacts 26 that are disposed and
arranged on the cartridge body 25 so that when properly inserted into the scanning
carriage, electrical contact is established between corresponding electrical contacts
(not shown) associated with the printer portion 12. Each of the electrical contacts 26
is electrically connected to the printhead 24 by each of a plurality of electrical

conductors (not shown). In this manner, activation signals from the printer portion 12
are provided to the inkjet printhead 24.
In the preferred embodiment, the electrical contacts 26 are defined in a
flexible circuit 28. The flexible circuit 28 includes an insulating material such as
polyimide and a conductive material such as copper. Conductors are defined within
the flexible circuit to electrically connect each of the electrical contacts 26 to
electrical contacts defined on the printhead 24. The printhead 24 is mounted and
electrically connected to the flexible circuit 28 using a suitable technique such as tape
automated bonding (TAB).
In the exemplary embodiment shown in Fig. 2, the print cartridge is a 3 color
cartridge containing yellow, magenta, and cyan inks within a corresponding reservoir
portion. The printhead 24 includes drop ejection portions 30, 32 and 34 for ejecting
ink corresponding, respectively, to yellow, magenta, and cyan inks. The electrical
contacts 26 include electrical contacts associated with activation signals for each of
the yellow, magenta, and cyan drop generators 30,32, 34, respectively.
In the preferred embodiment, the black ink cartridge 16 shown in Fig. 1 is
similar to the color cartridge 14 shown in Fig- 2 except the black cartridge makes use
of two drop ejection portions instead of three shown on the color cartridge 14. The
method and apparatus of the present invention will be discussed herein with respect to
the black cartridge 16. However, the method and apparatus of the present invention is
applicable to the color cartridge 14 as well.
Fig. 3 depicts a simplified electrical block diagram of the printer portion 12
and one of the print cartridges 16. The printer portion 12 includes a print control
device 36, a media transport device 38 and a carriage transport device 40. The print
control device 36 provides control signals to the media transport device 38 to pass the
media 22 through a print zone whereupon ink is deposited on the print media 22. In
addition, the print control device 36 provides control signals for selectively moving
the scanning carriage 18 across the media 22, thereby defining a print zone. As the
media 22 is stepped past the printhead 24 or through the print zone the scanning
carriage 18 is scanned across the print media 22. While the printhead 24 is scanned
the print control device 36 provides activation signals to the printhead 24 to

selectively deposit ink on print media to accomplish printing. Although, the printing
system 10 is described herein as having the printhead 24 disposed in a scanning
carriage there are other printing system 10 arrangements as well. These other
arrangements involve other arrangements of achieving relative movement between the
printhead and media such as having a fixed printhead portion and moving the media
past the printhead or having fixed media and moving the printhead past the fixed
media.
Fig. 3 is simplified to show only a single print cartridge 16. In general, the
print control device 36 is electrically connected to each of the print cartridges 14 and
16. The print control device 36 provides activation signals to selectively deposit ink
corresponding to each of the ink colors to be printed.
Fig. 4 depicts a simplified electrical block diagram showing greater detail of
the print control device 36 within the printer portion 12. and the printhead 24 within
the print cartridge 16. The print control device 36 includes a source of drive current,
an address generator, and an enable generator. The source of drive current, address
generator and enable generator provide drive current, address and enable signals
under control of the control device or controller 36 to the printhead 24 for selectively
activating each of a plurality of drop generators associated therewith.
In the preferred embodiment, the source of drive current provides 16 separate
drive current signals designated P (1-16). Each drive current signal provides
sufficient energy per unit time to activate the drop generator to eject ink. In the
preferred embodiment, the address generator provides 13 separate address signals
designated A (1-13) for selecting a group of drop generators. In this preferred
embodiment the address signals are logic signals. Finally, in the preferred
embodiment, the enable generator provides 2 enable signals designated E (1-2) for
selecting a subgroup of drop generators from the selected group of drop generators.
The selected subgroup of drop generators are activated if drive current provided by
the source of drive current is supplied. Further detail of the drive signals, address
signals and enable signals will be discussed with respect to Figs. 9-11.
The printhead 24 shown in Fig. 4 includes a plurality of groups of drop
generators with each group of drop generators connected to a different source of drive

current In the preferred embodiment, the printhead 24 includes 16 groups of drop
generators. The first group of drop generators is connected to the source of drive
current labeled P(l), the second group of drop generators are each connected to the
source of drive current designated P(2), the third group of drop generators is
connected to the source of drive current designated P(3), and so on with the sixteenth
group of drop generators each connected to the source of drive current designated
P(16).
Each of the groups of drop generators shown in Fig. 4 are connected to each of
the address signals designated A(l-13) provided by the address generator on the print
control device 36. In addition, each of the groups of drop generators are connected to
the two enable, signals designated E(l-2) provided by the address generator on the
print control device 36. Greater detail of each of the individual groups of drop
generators designated will now be discussed with respect to Fig. 5.
Fig. 5 is a block diagram representing a single group of drop generators from
the plurality of groups of drop generators shown in Fig. 4. In the preferred
embodiment, the single group of drop generators shown in Fig. 5 is a group of 26
individual drop generators each connected to a common source of drive current The
group of drop generators shown in Fig. 5 are all connected to the common source of
drive current designated P(l) of Fig. 4.
The individual drop generators within the group of drop generators are
organized in drop generator pairs with each pair of drop generators connected to a
different source of address signals. For the embodiment shown in Fig. 5, the first pair
of drop generators are connected to a source of address signals designated A(l), the
second pair of drop generators are connected to a second source of address signals
designated A(2), the third pair of drop generators are connected to a source of address
signals designated A(3) and so on with the thirteenth pair of drop generators
connected to the thirteenth source of address signals designated A(13).
Each of the 26 individual drop generators shown in Fig. 5 are also connected
to the source of enable signals. In the preferred embodiment, the source of enable
signals is a pair of enable signals designated E(l-2).

The remaining groups of drop generators shown in Fig. 4 that are connected to
the remaining sources of drive current designated P(2) through P( 16) are connected in
a manner similar to the first group of drop generators shown in Fig. 5. Each of the
remaining groups of drop generators are connected to a different source of drive
current as designated in Fig. 4 instead of the source of drop current P(l) shown in
Fig. 5. Greater detail of each individual drop generator shown in Fig. 5 will now be
discussed with respect to Fig. 6.
Fig. 6 shows one preferred embodiment of an individual drop generator
designated 42. The drop generator 42 represents one individual drop generator shown
in Fig. 5. As shown in Fig. 5 two individual drop generators 42 make up a pair of
drop generators 42 that are each connected to a common source of address signals.
The individual drop generator shown in Fig. 6 represents one of the pair of drop
generators 42 connected to address source 1 designated A(l) of Fig. 5. All sources of
signals such as address signals A(l) and enable signals E(I-2) discussed with respect
to Figs. 6 and 7 are signals that are provided between the corresponding source of
signals and the common reference point 46. In addition, the source of drive current is
provided between the corresponding source of drive current designated P(l) and the
common reference point 46.
The drop generator 42 includes a heating element 44 connected between the
source of drive current. For the particular drop generator 42 shown in Fig. 6 the
source of drive current is designated P(l). The heating element 44 is connected in
series with a switching device 48 between the source of drive current P(1) and the
common reference point 46. The switching device 48 includes a pair of controlled
terminals connected between the heating element 44 and the common reference point
46. Also included with the switching device 48 is a control terminal for controlling
the controlled terminals. The switching device 48 is responsive to activation signals
at the control terminal for selectively allowing current to pass between the pair of
controlled terminals. In this manner, activation of the control terminals allows drive
current from the source of drive current designated P(l) to pass through the heating
element 44 thereby producing heat energy that is sufficient to eject ink from the
printhead 24.

In one preferred embodiment, the heating element 44 is a resistive heating
element and the switching device 48 is a field effect transistor (FET) such as an
NMOS transistor.
The drop generator 42 further includes a second switching device SO and a
third switching device 52 for controlling activation of the control terminal of the
switching device 48. The second switching device has a pair of controlled terminals
connected between a source of address signals and the control terminal of switching
device 48. The third switching device 52 is connected between the control terminal of
switching device 48 and the common reference point 46. Each of the second and
third switching devices SO and 52, respectively, selectively control the activation of
the switching device 48.
The activation of switching device 48 is based on each of the address signal
and enable signal. For the particular drop generator 42 shown in Fig. 6 the address
signal is represented by A(l), the first enable signal represented by E(l) and a second
enable signal represented by E(2). The first enable signal E(l) is connected to the
control terminal of the second switching device 50. The second enable signal
represented by E(2) is connected to the control terminal of the third switching device
52. By controlling the first and second enable signals, E(l-2), and the address signal,
A(l), the switching device 48 is selectively activated to conduct current through the
heating element 44 if drive current is present from the source of drive source P(l).
Similarly, the switching device 48 is inactivated to prevent current from being
conducted through the heating resistor 44 even if the source of drive current P(l) is
active.
The switching device 48 is activated by the activation of the second switching
device 50 and the presence of an active address signal at the source of address signals,
A( I). In the preferred embodiment where the second switching device is a field effect
transistor (FET) the controlled terminals associated with the second switching device
are source and drain terminals. The drain terminal is connected to the source of
address signals A( 1) and the source terminal is connected to the controlled terminal of
the first switching device 48. The control terminal for the FET transistor switching
device 50 is a gate terminal. When the gate terminal, connected to the first enable

signal E(l), is sufficiently positive relative to the source terminal and the source of
address signals, A(l), provides a voltage at the drain terminal that is greater than the
voltage at the source terminal then the second switching device SO is activated.
The second switching device, if active, provides current from the source of
address signals A(l) to the control terminal or gate of the switching device 48. This
current, if sufficient, activates the switching device 48. The switching device 48, in
the preferred embodiment, is a FET transistor having a drain and source as the
controlled terminals with the drain connected to the heating element 44 and the source
connected to the common reference terminal 46.
In the preferred embodiment, the switching device 48 has a gate capacitance
between the gate and source terminals. Because this switching device 48 is relatively
large to conduct relatively large currents through the heating device 44, then the gate
to source capacitance associated with the switching device 48 tends to be relatively
large. Therefore, to enable or activate the switching device 48, the gate or control
terminal must be charged sufficiently so that the switching device 48 is activated to
conduct between the source and drain. The control terminal is charged by the source
of address signals A(l) if the second switching device 50 is active. The source of
address signals A(l) provides current to charge the gate to source capacitance of the
switching device 48. It is important that the third switching 52 be inactive when the
switching device 48 is active to prevent a low resistance path from being formed
between the source of address signals A(1) and the common reference terminal 46.
Therefore, the enable signal E(2) is inactive while the switching device 48 is active or
conducting.
The switching device 48 is inactivated by activating the third switching device
52 to reduce the gate to source voltage sufficiently to inactivate me switching device
48. The third switching device 52 in the preferred embodiment is a FET transistor
having drain and source as the controlled terminals with the drain connected to the
control terminal of switching device 48. The control terminal is a gate terminal that is
connected to the second source of enable signals E(2). The third switching device 52
is activated by activation of the second enable signal E(2) that provides a voltage at
the gate that is sufficiently large relative to a voltage at the source of the third

switching device 52. Activation of the third switching device 52 causes the controlled
terminals or drain and source terminals to conduct thereby reducing a voltage between
the control terminal or gate terminal of the switching device 48 and the source
terminal of the switching device 48. By sufficiently reducing the voltage between the
gate terminal and the source terminal of the switching device 48 the switching device
48 is prevented from being partially turned on by capacitive coupling.
While the third switching device 52 is active, the second switching 50 is
inactive to prevent sinking large amounts of current from the source of address
signals, A(l), to the common reference terminal 46. The operation of the individual
drop generator 42 will be discussed in more detail with respect to the timing diagrams
shown in Figs, 8 through 11.
Fig. 7 shows greater detail of a pair of drop generators that are formed by the
drop generator designated 42 and a drop generator designated 42'. Each of the drop
generators 42 and 42' that form the pair of drop generators are identical to the drop
generator 42 discussed previously with respect to Fig. 6. The pair of drop generators
are each connected to a source of address signals represented by A(l) shown in Fig. 5.
Each of the drop generators 42 and 42' are connected to a common source of drive
current P(l) and common source of address signals A(l). However, the first and
second enable signals E(l) and E(2), respectively, are connected differently in drop
generator 42' from drop generator 42. In drop generator 42', the first enable signal
E(l) is connected to the gate or control terminal of the third switching device 52' in
contrast to drop generator 42 in which the first enable signal E(l) is connected to the
gate or control terminal of the second switching device 50. Similarly, the second
enable signal E(2) is connected to the gate or control terminal of the second switching
device 50' in the drop generator 42' in contrast to the drop generator 42 where the
second enable signal E(2) is connected to the gate or control terminal of the third
switching device 52.
The connection of the first and second enable signals E1 and E2 for the pair of
drop generators 42 and 42' ensures that only a single drop generator of the pair of
drop generators will be activated at a given time. As will be discussed later, it is
important that within the group of drop generators that are connected to a common

source of drive current that no more than one of these drop generators is active at the
same time. The drop generators that are connected to a common source of drive
current tend to be positioned near each other on the printhead. Therefore, by ensuring
that no more than one of the drop generators that are connected to a common source
of drive current of these is active at me same time tends to prevent fiuidic crosstalk
between these proximately positioned drop generators.
In the preferred embodiment, each of the pairs of drop generators shown in
Fig. 5 are connected in a manner similar to the pair of drop generators shown in Fig.
7. In addition, each of the groups of drop generators connected to a common source
of drive current shown in Fig. 4 are connected in a manner similar to the group of
drop generators shown in Fig. S.
Fig. 8 is a timing diagram illustrating the operation of printhead 24. The
printhead 24 has a cycle time or period of time for each of the drop generators on the
printhead 24 can be activated. This period of time is represented by a time T shown
in Fig. 8. The time T can be divided into 29 intervals of time with each interval
having the same duration. These intervals of time are represented by time slots 1
through 29. Each of the first 26 time slots represents a period in which a group of
drop generators can be activated if the image to be printed so requires. Time slots 27,
28 and 29 represent intervals of time during a printhead cycle in which no drop
generators are activated. The time slots 27,28, and 29 are used by the printing system
10 to perform a variety of functions such as resynchronize the carriage 18 position
and drop generator activation data and transfer activation data from the printer portion
12 to the printhead 24, to name a couple.
The 13 different sources of address signals represented by A(l) through A(13)
are each shown. In addition, each of the first and second enable signals represented
by E(l) and E(2) are also shown. Finally, each of the sources of drive current P (1-
16) are also shown, grouped together. It can be seen from Fig. 8 that the address
signals are each activated periodically with the period of activation for each address
signal being equal to the cycle time T of the printhead 24. In addition, no more man
one address signal is active at the same time. Each address signal is active during two
consecutive time slots.

Each of the enable signals £(1) and E(2) are periodic signals having a period
that is equal to two time slots. The enable signals E(l) and E(2) each have a duty
cycle that is less than or equal to 50%. Each of the enable signals are out of phase
with each so that only one of enable signal E( 1) or E(2) are active at the same time.
In operation, repeating patterns of address signals provided by each of the 13
sources of address signals A(l-13) are provided to the printhead 24 by the print
control device 36. In addition, repeating patterns of enable signals for the first and
second enable signals, E(l) and E(2), respectively, are also provided by the print
control device 36 to the printhead 24. Both the address and enable signals are
generated independent of the image description or image to be printed. Each of the
16 sources of drive current designated P (1-16) are selectively provided during each
of the 26 time slots for each complete cycle for the inkjet printhead 24. The source of
drive current P(l-16) is selectively applied based on the image description or the
image to be printed. During the first time slot, the sources of drive current P(l-16)
may all be active, none of them active or any number of them active, depending upon
the image to be printed. Similarly, for time slots 2- 26, each of the sources of drive
current P (1-16) are individually selectively activated as required by the print control
device 36 to form the image to be printed.
Fig. 9 is a preferred timing for each of the sources of drive current P (1-16),
sources of address signals A (1-13) and enable signals E (1-2) for the printhead 24 of
the present invention. The timing in Fig. 9 is similar to the timing of Fig. 8 except
that each source of address signals A(l-13) instead of remaining active over the entire
two consecutive time slots shown in Fig. 8, each address is active for only a portion of
each of the two time slots shown in Fig. 9. In this preferred embodiment, each of the
address signals A(l-13) are active at the beginning of each time slot the address signal
is active. In addition, the duty cycle of each of the first and second enable signals
reduced from the nearly 50% duty cycle shown in Fig. 8. Further detail of the timing
of the address enable and drive current will now be discussed with respect to Figs. 10
and 11.
Fig. 10 shows greater detail of time slots 1 and 2 for the timing diagram of
described in Fig. 8. Because the only active address signal during time slot 1 and 2 is

A(l) only the address signal A(l) need be shown in Fig 10. As discussed previously,
it is important that the first and second enable signals, E(l) and E(2) respectively, not
be active at the same time to prevent providing a low resistance path to the common
reference point 46 thereby sinking current from the source of address signals A(l-13).
Therefore, the duty cycle of each of the first and second enable signals, £(1) and E(2)
respectively, should be less than 50%. In Fig. 10 the time interval labeled TE between
the transition from active to inactive for the first enable signal E(l) and the transition
from inactive to active for the second enable signal E(2) should be greater than zero.
The enable signal should be active before drive current is provided by the
source of drive current to ensure that the gate of capacitance of the switching
transistor 48 is sufficiently charged to activate the drive transistor 48. The time
interval labeled Ts represents the time between the first enable E(1) active and the
application of the drive current by the sources of drive current P(l-16). A similar
time interval is required for the time between the second enable E(2) active and the
application of the drive current by the sources of drive current P(l-16).
The enable signal E(l) should remain active for a period of time after the
source of drive current P(1-16) transitions from active to inactive as designated TH.
This period of time TH referred to as hold time is sufficient to ensure that drive
current is not present at the switching device 48 when the switching device 48 is
inactivated. Inactivating the switching device 48 while the switching device 48 is
conducting current between the controlled terminals can damage the switching device
48. The hold time TH provides margin to ensure the switching device 48 is not
damaged. The duration of the drive current signal P(l-16) is represented by time
interval labeled TD. The duration of drive current signal P(l-16) is selected to be
sufficient to provide drive energy to the heating element 44 for optimum drop
formation.
Fig. 11 shows further detail of the preferred timing for time slots 1 and 2 for
the timing diagram of Fig. 9. As shown in Fig. 11 for time slot 1 the source of
address signals A(l) and the source of enable signals E(l) do not remain active the
entire duration tiiat the source of drive current remains active. Once the gate
capacitance of the switching transistor 48 and 48' shown in Fig.7 is charged, the

transistor 48 and 48' remain conducting the remaining duration that the source of
drive current remains active. In this manner, the gate capacitance of the switching
device 48 and 48' acts as a storage device or memory device that retains an activated
state. The switching device 48 and 48* are selected to have sufficient capacitance so
that charge stored within this capacitance remains beyond a threshold amount to keep
the switching device 48 and 48' conducting while the drive current signal is active.
The source of drive signals designated P(l-16) then provides the drive energy that is
necessary for optimum drop formation.
Similar to Fig. 10 the time interval labeled TS represents the time between the
first enable £(1) active and the application of the drive current by the sources of drive
current P(l-16). An interval of time labeled TAH represents a hold time the source of
address signals A(l) must remain active after the first enable signal E(l) is inactive to
ensure the gate capacitance for transistor 48' is in the proper state. If the source of
address signals were to change state before the first enable signal E(l) signal becomes
inactive the wrong state of charge can exist at the gate of transistors 48 and 48'.
Therefore, it is important that the time interval labeled TAH be greater than 0. An
interval of time labeled TEH represents a hold time the second enable signal £(2) must
be active after the source of drive current P(l-16) becomes active. During the time
interval transistor 52 in Fig. 7 is activated by the second enable signal E(2) to
discharge the gate capacitance of transistor 48. If this duration is not sufficiently long
to discharge the gate of transistor 48 the heating element 44 may improperly be
activated or partially activated.
Operation of the inkjet printhead 24 using the preferred timing shown Fig. 11
has important performance advantages over the use of the timing shown in Fig. 10. A
minimum time required for each drop generator 42 activation for the timing shown in
Fig. 10, is equal to the sum of time intervals Ts, TD, TE and TH. In contrast, the timing
shown in Fig. 11 has a minimum time that is required for each drop generator 42
activation that is equal to the sum of time intervals Ts, and TD. Because TD and Ts is
the same for each of the timing diagrams, the minimum time required for activation of
a drop generator 42 is less in Fig. 11 than in Fig. 10. Both the address hold time TAH
and the enable hold time TEH do not contribute to the minimum time interval for drop

generator 42 activation in the preferred timing shown in Fig. 11 thereby allowing each
time slot to be a smaller time interval than in Fig. 10. Reduction of the time interval
required for each time slot reduces the cycle period designated T in Figs. 8 and 9
thereby increasing the printing rate for the printhead 24.
The method and apparatus of the present invention allows 416 individual drop
generators to be individually activated using 13 address signals, two enable signals,
and 16 sources of drive current In contrast, the use of previously used techniques
whereby an array of drop generators having 16 columns and 26 rows would require
26 individual addresses to individually select each row with each column being
selected by each source of drive current The present invention provides significantly
fewer electrical interconnects to address the same number of drop generators. The
reduction of electrical interconnects reduces the size of the printhead 24 thereby
significantly reducing the costs of the printhead 24.
Each individual drop generator 42 as shown in Fig. 6 does not require a
constant power supply or bias circuit but instead relies on the input signals such as
address, source of drive current and enable signals to supply power or activate the
drop generator 42. As discussed previously with respect to the timing of the signals,
it is important that these signals be applied in the proper sequence in order to have
proper operation of the drop generator 42. Because the drop generator 42 of the
present invention does not require constant power, the drop generator 42 can be
implemented in relatively simple technology such as NMOS which requires fewer
manufacturing steps men more complex technology such as CMOS. Use of a
technology that has lower manufacturing costs further reduces the costs of the
printhead 24. Finally, the use of fewer electrical interconnects between the printer
portion 36 and the printhead 24 tends to reduce the costs of the printer portion 36 as
well as increase the reliability of the printing system 10.
Although the present invention has been described in terms of a preferred
embodiment that makes use of 13 address signals, two enable signals, and 16 sources
of drive current to selectively activate 416 individual drop generators other
arrangements are also contemplated. For example, the present invention is suitable
for selectively activating different numbers of individual drop generators. The

selective activation of different numbers of individual nozzles may requite different
numbers of one or more of the address signals, enable signals, and sources of drive
current to properly control different numbers of drop generators. In addition, there
are other arrangements of address signals, enable signals, and sources of drive current
to control the same number of drop generators as well.

We claim:
1. An inkjet printing system comprising:
an inkjet printhead having drop generators and a plurality of electrical contacts, the
plurality of electrical contacts including address contacts, enable contacts, and drive contacts,
wherein the drop generators are organized in a plurality of groups of drop generators with each
of the plurality of groups of drop generators connected to a different drive current contacts and
wherein each of the plurality of groups of drop generators includes subgroups of drop generators
and each subgroup of drop generators within the group of drop generators is connected to a
different address contact of the plurality of address contacts;
a printing device having a plurality of electrical contacts including address contacts,
enable contacts and drive current contacts, the plurality of electrical contacts configured to
establish electrical contact with corresponding electrical contacts on the inkjet printhead upon
insertion of the inkjet printhead into the printing device; and
wherein the printing device provides periodic address signals to the address contacts and
periodic enable signals to the enable contacts and wherein the printing device selectively applies
drive current based on image descriptions to the drive current contacts; and
wherein the printhead is responsive to periodic signaling from each of the address and
enable signals and wherein the printhead is responsive to the selective application of drive
current to selectively eject ink from the printhead to form images on print media.
2. The inkjet printing system as claimed in claim 1 wherein the inkjet printing system is
configured to provide relative movement between the inkjet printhead and print media as the
inkjet printhead is selectively activated to deposit ink on print media.
3. The inkjet printing system as claimed in claim 1 wherein the plurality of electrical contacts
includes thirteen address contacts, two enable contacts and sixteen drive current contacts.
4. The inkjet printing system as claimed in claim 1 wherein the inkjet printhead includes a
plurality of drop generators with each drop generator of the plurality of drop generators
configured for connection to an address contact, an enable contact and a drive current contacts of
the plurality of electrical contacts wherein each drop generator is configured to eject ink
therefrom if signals at each of the the address contact, the enable contact and the drive current
contacts are active.
5. The inkjet printing system as claimed in claim 1 wherein the inkjet printhead includes 416
individual drop generators.
6. The inkjet printing system as claimed in claim 1 wherein each of the plurality of subgroups of
drop generators is a pair of drop generator.

7. The-inkjet printing system as claimed in claim 1 wherein the printing device comprises:
a printhead control portion for providing the address signals for identifying a first set of
drop ejection devices on the inkjet printhead, the printhead control portion providing the enable
signals for identifying a subset of drop ejection devices from the set of drop ejection devices, the
printhead control portion providing drive current to selected drop ejection devices on the inkjet
printhead,wherein only drop ejection devices within the identified subset that are provided drive
current are activated to eject ink.
8. The inkjet printing system as claimed in claim 7 wherein the printing device is configured to
receive a print cartridge, the print cartridge having a plurality of electrical contacts so disposed
and arranged on the print cartridge to engage and operably couple with corresponding electrical
contacts on the printing device and wherein the print cartridge includes an inkjet printhead
electrically connected to the plurality of electrical contacts.
9. The-inkjet printhead as claimed in claim 1 wherein the inkjet further comprises:

a plurality of contacts configured to establish connection, upon insertion of the inkjet
printhead into the printing device, with a corresponding plurality of contacts on the printing
device, 'the plurality of contacts on the inkjet printhead receiving drive current and periodic
address and enable signals from the printing device; and
wherein the inkjet printhead is responsive to periodic signal from each of the address and
enable signals and wherein the inkjet printhead is responsive to selective application of drive
current based on image descriptions to selectively eject ink from the inkjet printhead.
10. The inkjet printhead as claimed in claim 9 wherein the printing device is configured to
provide relative movement between the inkjet printhead and print media as the inkjet printhead is
selectively activated to deposit ink on media.
11. The inkjet as claimed in claim 9 wherein the plurality of electrical contacts on the inkjet
printhead includes thirteen address contacts, two enable contacts and sixteen drive current
contacts.
12. The inkjet printhead as claimed in claim 9 includes a plurality of drop generators with each
drop generator of the plurality of drop generators configured for connection to an address
contact, an enable contact and a pair of drive current contacts of the plurality of electrical
contacts wherein each drop generator is configured to eject ink therefrom if signals at each the an
address contact, an enable contact and a pair of drive current contacts are active.
13. The inkjet printing system as claimed in claim 1 wherein the inkjet printhead further
comprises:

an energy storage device for storing energy;
an energy charging device responsive to a first enable signal for storing energy in the
energy storage device;
an energy discharging device responsive to a second enable signal for discharging energy
in the energy storage device; and
a drop generating device for dispensing ink from the inkjet printhead upon activation, the
drop generating device activated by a drive current signal active and energy stored in the energy
storage device being greater than a threshold energy level.
14. The inkjet printing system as claimed in claim 13 wherein the energy storage device is a
capacitor and wherein each of the energy charging device and energy discharging devices are
transistors.
15. The inkjet printing system as claimed in claim 13 wherein the drop generating device
includes a resistive heating device and a FET transistor having drain and source terminals
connected in series with the resistive heating device and wherein the energy storage device is a
gate to source capacitance of the FET transistor.
16. The inkjet printing system as claimed in claim 15 wherein the energy charging device is a
second transistor having a pair of controlled terminals connected in series between a gate
terminal of the FET transistor and an energy source with a control terminal of the second
transistor is connected to a source of the first enable signal and wherein the energy discharging
device is a third transistor having a pair of controlled terminals connected in series between a
gate terminal of the FET transistor and a discharge source with a control terminal of the third
transistor is connected to a source of the first enable signal.
17. The inkjet printhead as claimed in claim 16 wherein the energy source is an address terminal for receiving an address signal and wherein the discharge source is a common reference terminal.
18. The inkjet printhead as claimed in claim 1 wherein the inkjet printhead further_comprises:
a plurality of groups of drop generators for depositing ink on media with each of the
plurality of groups of drop generators capable of activation once over a printhead activation
cycle, the printhead activation cycle being subdivided into a plurality of times lots with each of
the plurality of groups of drop generators having a corresponding timeslot associated therewith;
and
wherein the activation signal is active in the corresponding timeslot before drive current
is provided and wherein the activation signal is active for a duration that is less that a duration
drive current is provided and wherein each drop generator within each group of drop generators
when activated is active for the duration that drive current is provided.

19. The inkjet printhead as claimed in claim 18 wherein the activation signal is an address signal
and first and second enable signals and wherein each drop generator within each group of drop
generators is activated if the address signal is activated and the first enable is activated.
20. The inkjet printing system as claimed in claim 1 wherein the enable signals include a first enable signal and a second enable signal, wherein the inkjet printhead includes a plurality of
pairs of drop generators, and wherein each pair of drop generators includes a first drop generator
configured to be activated by the first enable signal and a second drop generator configured to be
activated by the second enable signal.
21. The printing system as claimed in claim 1 wherein a ratio of the address contacts to the
enable contacts is approximately 6.5 to 1.
22. The printing system as claimed in claim 1 wherein the plurality of electrical contacts include
A address contacts, E enable contacts, and D drive current contacts, and wherein the printhead
includes an array of (AxExD) drop generators controlled by the A address contacts, the E enable
contacts, and the D drive current contacts.
23. A method for operating an inkjet printhead having plurality of drop generators for ejecting ink in response to activation, the plurality of drop generators organized in groups of drop
generators with each group of drop generators connected to a common source of activation
current, comprising the steps of:
receiving a first time varying voltage having a constant frequency for selecting subgroups
of drop generators within the groups of drop generators; and
receiving a second time varying voltage having constant frequency for selecting
individual drop generators within the selected subgroup of drop generators, wherein the selected
individual drop generators arc activated based drive current delivered thereto.
24. The method as claimed in claim 23 further including selectively delivering drive current to drop generators based on both the first and second time varying voltage and the image to be
printed.
25. The method as claimed in claim 23 wherein the first and second time varying voltage is a
first and second logic signal.
26. The method as claimed in claim 23 wherein the first time varying voltage is an enable signal
and the second time varying voltage is an address signal.

27. The method as claimed in claim 23 wherein the first time varying voltage is a first and
second enable signals and the second time varying voltage is an address signal.



AN INKJET PRINTING SYSTEM


ABSTRACT OF THE DISCLOSURE
The present disclosure relates to an inkjet printing system (10) that includes an inkjet printhead
(24) having a plurality of electrical contacts (26). The plurality of electrical contacts (26) include
address contacts and enable contacts for enabling drop generators (42) and drive current contacts
for providing drive current to enable drop generators (42) for selectively ejecting ink therefrom.
The printing system (10) includes a printing device having a plurality of electrical contacts (26)
including address contacts, enable contacts and drive current contacts. The plurality of electrical
contacts (26) are configured to establish electrical contact with corresponding electrical contacts
(26) on the inkjet printhead (24) upon insertion of the inkjet printhead (24) into the printing
device. The printing device provides periodic address signals (A1-13) and enable signals (E1-2)
to the address and enable contacts one the printhead (24). In addition, the printing device
selectively applies drive current to accomplish forming images on print media (22).

Documents:

557-KOLNP-2003-(06-01-2012)-CORRESPONDENCE.pdf

557-KOLNP-2003-(09-12-2013)-CORRESPONDENCE.pdf

557-KOLNP-2003-(09-12-2013)-FORM-1.pdf

557-KOLNP-2003-(09-12-2013)-FORM-13.pdf

557-KOLNP-2003-(09-12-2013)-PETITION UNDER RULE 137.pdf

557-KOLNP-2003-(22-03-2012)-CORRESPONDENCE.pdf

557-KOLNP-2003-(22-03-2012)-PA-CERTIFIED COPIES.pdf

557-kolnp-2003-ABSTRACT-1.21.pdf

557-kolnp-2003-abstract.pdf

557-KOLNP-2003-ABSTRACT1.1.pdf

557-kolnp-2003-ASSIGNMENT-1.1.pdf

557-KOLNP-2003-ASSIGNMENT.pdf

557-kolnp-2003-CLAIMS-1.2.pdf

557-kolnp-2003-claims.pdf

557-KOLNP-2003-CLAIMS1.1.pdf

557-KOLNP-2003-CORRESPONDENCE 1.1.pdf

557-kolnp-2003-CORRESPONDENCE-1.2.pdf

557-kolnp-2003-correspondence.pdf

557-KOLNP-2003-CORRESPONDENCE1.1.pdf

557-kolnp-2003-DESCRIPTION (COMPLETE)-1.2.pdf

557-kolnp-2003-description (complete).pdf

557-KOLNP-2003-DESCRIPTION (COMPLETE)1.1.pdf

557-kolnp-2003-DRAWINGS-1.2.pdf

557-kolnp-2003-drawings.pdf

557-KOLNP-2003-DRAWINGS1.1.pdf

557-kolnp-2003-EXAMINATION REPORT-1.1.pdf

557-kolnp-2003-examination report.pdf

557-kolnp-2003-FORM 1-1.1.pdf

557-KOLNP-2003-FORM 1.pdf

557-kolnp-2003-FORM 13-1.1.pdf

557-kolnp-2003-form 13.pdf

557-kolnp-2003-FORM 18-1.1.pdf

557-kolnp-2003-form 18.pdf

557-kolnp-2003-FORM 2-1.1.pdf

557-KOLNP-2003-FORM 2.1.pdf

557-kolnp-2003-form 2.pdf

557-kolnp-2003-FORM 26-1.1.pdf

557-kolnp-2003-form 26.pdf

557-KOLNP-2003-FORM 3.1.pdf

557-kolnp-2003-FORM 3.pdf

557-kolnp-2003-FORM 5-1.2.pdf

557-KOLNP-2003-FORM 5.1.pdf

557-kolnp-2003-form 5.pdf

557-kolnp-2003-GPA-1.1.pdf

557-kolnp-2003-gpa.pdf

557-kolnp-2003-INTERNATIONAL PUBLICATION.pdf

557-kolnp-2003-INTERNATIONAL SEARCH REPORT & OTHERS.pdf

557-kolnp-2003-OTHERS-1.2.pdf

557-KOLNP-2003-OTHERS.pdf

557-KOLNP-2003-OTHERS1.1.pdf

557-kolnp-2003-PA-1.1.pdf

557-KOLNP-2003-PA.pdf

557-kolnp-2003-PETITION UNDER RULE 137.pdf

557-kolnp-2003-REPLY TO EXAMINATION REPORT-1.1.pdf

557-KOLNP-2003-REPLY TO EXAMINATION REPORT.pdf

557-kolnp-2003-SPECIFICATION-COMPLETE.pdf

557-kolnp-2003-specification.pdf

557-KOLNP-2003-SPECIFICATION1.1.pdf

557-kolnp-2003-TRANSLATED COPY OF PRIORITY DOCUMENT-1.1.pdf

557-kolnp-2003-translated copy of priority document.pdf


Patent Number 259260
Indian Patent Application Number 557/KOLNP/2003
PG Journal Number 10/2014
Publication Date 07-Mar-2014
Grant Date 05-Mar-2014
Date of Filing 01-May-2003
Name of Patentee HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P.
Applicant Address 11445 COMPAQ CENTER DRIVE WEST, HOUSTON TX 77070, UNITED STATES OF AMERICA
Inventors:
# Inventor's Name Inventor's Address
1 COWGER BRUCE 37194 HELM DR. CORVALLIS, OR 97330
2 TORGERSON JOSPEH M 24901 HIDDEN VALLEY ROAD PHILOMATH, OR 97370
3 HURST DAVID M 560 NW LEPRECHAUN LANE CORVALLIS, OR 97330
4 MACKENZIE MARK H 1448 SW BRIDIE DRIVE CORVALLIS OR 97330
PCT International Classification Number B41J 2/05
PCT International Application Number PCT/US2001/46041
PCT International Filing date 2001-10-29
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/702,267 2000-10-30 U.S.A.