Patent Description:
Image formation is a procedure whereby a digital image is recreated by propelling droplets of ink or another type of print fluid onto a medium, such as paper, plastic, a substrate for 3D printing, etc. Image formation is commonly employed in apparatuses, such as printers (e.g., inkjet printer), facsimile machines, copying machines, plotting machines, multifunction peripherals, etc. The core of a typical jetting apparatus or image forming apparatus is one or more liquid-droplet ejection heads (referred to generally herein as "printheads") having nozzles that discharge liquid droplets, a mechanism for moving the printhead and/or the medium in relation to one another, and a controller that controls how liquid is discharged from the individual nozzles of the printhead onto the medium in the form of pixels.

A typical printhead includes a plurality of nozzles aligned in one or more rows along a discharge surface of the printhead. Each nozzle is part of a "jetting channel", which includes the nozzle, a pressure chamber, and a diaphragm that vibrates in response to an actuator, such as a piezoelectric actuator. A printhead also includes a driver circuit that controls when each individual jetting channel fires based on image or print data. To jet from a jetting channel, the driver circuit provides a jetting pulse to the actuator, which causes the actuator to deform a wall of the pressure chamber (i.e., the diaphragm). The deformation of the pressure chamber creates pressure waves within the pressure chamber that eject a droplet of print fluid (e.g., ink) out of the nozzle. <CIT> discloses a drive circuit for a printhead according to the preamble of claims <NUM> and <NUM>.

<CIT> discloses printing apparatus, control method for printing apparatus, and control program for printing apparatus.

Embodiments described herein provide enhanced driver circuits for printheads, and associated systems and methods. A conventional driver circuit for a printhead controls jetting of a single print fluid from jetting channels. For example, if a printhead was configured to jet two colors of ink, then two driver circuits would be implemented in the printhead. If a printhead was configured to jet four colors of ink, then four driver circuits would be implemented in the printhead. In the embodiments described herein, a single driver circuit is configured to control jetting of multiple print fluids. One technical benefit is that less electronics are needed in a printhead to jet multiple print fluids.

One embodiment comprises a driver circuit according to claim <NUM>. The driver circuit is communicatively coupled to actuators of the jetting channels. The driver circuit is configured to receive a drive waveform comprising non-jetting pulses and jetting pulses. The driver circuit is configured to receive gating signals comprising a first active gating signal designated for jetting the first print fluid, and a second active gating signal designated for jetting the second print fluid. The driver circuit is configured to selectively apply the non-jetting pulses and the jetting pulses from the drive waveform to the actuators of the first jetting channels based on the first active gating signal to jet the first print fluid, and to selectively apply the jetting pulses from the drive waveform to the actuators of the second jetting channels based on the second active gating signal to jet the second print fluid.

This embodiment further comprises a jetting period of the drive waveform includes a non-jetting pulse and a jetting pulse. For the jetting period, the driver circuit is configured to obtain print data for the first jetting channels and the second jetting channels, and select a gating signal from the gating signals for each of the first jetting channels and the second jetting channels based on the print data. When the gating signal selected for a first jetting channel of the first jetting channels comprises the first active gating signal, the driver circuit is configured to output the non-jetting pulse and the jetting pulse from the drive waveform as a first driver output signal to the actuator of the first jetting channel. When the gating signal selected for a second jetting channel of the second jetting channels comprises the second active gating signal, the driver circuit is configured to output the jetting pulse from the drive waveform as a second driver output signal to the actuator of the second jetting channel, where the non-jetting pulse is blocked from the second driver output signal based on the second active gating signal.

In another embodiment, the first active gating signal includes an active time window that corresponds with the non-jetting pulse and the jetting pulse, and the second active gating signal includes an active time window that corresponds with the jetting pulse.

In another embodiment, the non-jetting pulses and the jetting pulses are in the same voltage direction, and the non-jetting pulses have in-phase timing with a resonant frequency of the first jetting channels in response to the jetting pulses.

In another embodiment, the non-jetting pulses and the jetting pulses are in opposite voltage directions, and the non-jetting pulses have in-phase timing with a resonant frequency of the first jetting channels in response to the jetting pulses.

In another embodiment, the non-jetting pulses and the jetting pulses are in the same voltage direction, and the non-jetting pulses have out-of-phase timing with a resonant frequency of the first jetting channels in response to the jetting pulses.

In another embodiment, the non-jetting pulses and the jetting pulses are in opposite voltage directions, and the non-jetting pulses have out-of-phase timing with a resonant frequency of the first jetting channels in response to the jetting pulses.

In another embodiment, the actuators comprise piezoelectric actuators.

In another embodiment, the printhead further comprises a first manifold configured to supply the first print fluid to the first jetting channels, and a second manifold configured to supply the second print fluid to the second jetting channels.

In another embodiment, the first print fluid comprises a first color of ink, and the second print fluid comprises a second color of ink.

In another embodiment, the first jetting channels and the second jetting channels form a single row of nozzles.

In another embodiment, the first jetting channels form a first row of nozzles, and the second jetting channels form a second row of nozzles.

Another embodiment comprises a jetting apparatus comprising the printhead described above, and a jetting controller configured to provide the drive waveform and the gating signals to the printhead.

Another embodiment comprises a method for driving a printhead according to claim <NUM> comprising a plurality of jetting channels including first jetting channels configured to jet a first print fluid, and second jetting channels configured to jet a second print fluid. The method comprises receiving a drive waveform comprising non-jetting pulses and jetting pulses, and receiving gating signals comprising a first active gating signal designated for jetting the first print fluid, and a second active gating signal designated for jetting the second print fluid. The method further comprises selectively applying the drive waveform to the jetting channels by selectively applying the non-jetting pulses and the jetting pulses from the drive waveform to the actuators of the first jetting channels based on the first active gating signal to jet the first print fluid, and selectively applying the jetting pulses from the drive waveform to the actuators of the second jetting channels based on the second active gating signal to jet the second print fluid.

In another embodiment, a jetting period of the drive waveform includes a non-jetting pulse and a jetting pulse. For the jetting period, the selectively applying comprises obtaining print data for the first jetting channels and the second jetting channels, and selecting a gating signal from the gating signals for each of the first jetting channels and the second jetting channels based on the print data. When the gating signal selected for a first jetting channel of the first jetting channels comprises the first active gating signal, outputting the non-jetting pulse and the jetting pulse from the drive waveform as a first driver output signal to the actuator of the first jetting channel. When the gating signal selected for a second jetting channel of the second jetting channels comprises the second active gating signal, outputting the jetting pulse from the drive waveform as a second driver output signal to the actuator of the second jetting channel, where the non-jetting pulse is blocked from the second driver output signal based on the second active gating signal.

Another embodiment comprises a jetting control system for controlling a printhead comprising a plurality of jetting channels. The jetting control system comprises a jetting controller that includes at least one processor configured to generate a drive waveform comprising non-jetting pulses and jetting pulses, designate a first active gating signal for jetting a first print fluid, and designate a second active gating signal for jetting a second print fluid. The jetting control system further includes a driver circuit communicatively coupled to the jetting controller, and to actuators of the jetting channels. The driver circuit is configured to receive the drive waveform and gating signals from the jetting controller, where the gating signals include the first active gating signal and the second active gating signal. The driver circuit is configured to selectively apply the non-jetting pulses and the jetting pulses from the drive waveform to the actuators of a first subset of the jetting channels based on the first active gating signal to jet the first print fluid, and to selectively apply the jetting pulses from the drive waveform to the actuators of a second subset of the jetting channels based on the second active gating signal to jet the second print fluid.

The above summary provides a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is intended to neither identify key or critical elements of the specification nor delineate any scope particular embodiments of the specification, or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented later.

The figures and the following description illustrate specific exemplary embodiments. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the embodiments and are included within the scope of the embodiments. Furthermore, any examples described herein are intended to aid in understanding the principles of the embodiments, and are to be construed as being without limitation to such specifically recited examples and conditions.

<FIG> is a schematic diagram of a jetting apparatus <NUM> in an illustrative embodiment. A jetting apparatus <NUM> is a device or system that uses one or more printheads to eject a print fluid or marking material onto a medium. One example of jetting apparatus <NUM> is an inkjet printer (e.g., a cut-sheet or continuous-feed printer) that performs single-pass printing. Other examples of jetting apparatus <NUM> include a scan pass inkjet printer (e.g., a wide format printer), a multifunction printer, a desktop printer, an industrial printer, a 3D printer, etc. Generally, jetting apparatus <NUM> includes a mount mechanism <NUM> that supports one or more printheads <NUM> in relation to a medium <NUM>. Mount mechanism <NUM> may be fixed within jetting apparatus <NUM> for single-pass printing. Alternatively, mount mechanism <NUM> may be disposed on a carriage assembly that reciprocates back and forth along a scan line or sub-scan direction for multi-pass printing. Printheads <NUM> are a device, apparatus, or component configured to eject droplets <NUM> of a print fluid, such as ink (e.g., water, solvent, oil, or UV-curable), through a plurality of nozzles (not visible in <FIG>). The droplets <NUM> ejected from the nozzles of printheads <NUM> are directed toward medium <NUM>. Medium <NUM> comprises any type of material upon which ink or another marking material is applied by a printhead, such as paper, plastic, card stock, transparent sheets, a substrate for 3D printing, cloth, etc. Typically, nozzles of printheads <NUM> are arranged in one or more rows so that ejection of a print fluid from the nozzles causes formation of characters, symbols, images, layers of an object, etc., on medium <NUM> as printhead <NUM> and/or medium <NUM> are moved relative to one another. Jetting apparatus <NUM> may include a media transport mechanism <NUM> or a media holding bed <NUM>. Media transport mechanism <NUM> is configured to move medium <NUM> relative to printheads <NUM>. Media holding bed <NUM> is configured to support medium <NUM> in a stationary position while the printheads <NUM> move in relation to medium <NUM>.

Jetting apparatus <NUM> also includes a jetting apparatus controller <NUM> that controls the overall operation of jetting apparatus <NUM>. Jetting apparatus controller <NUM> may connect to a data source to receive print data, image data, or the like, and control each printhead <NUM> to discharge the print fluid on medium <NUM>. Jetting apparatus <NUM> also includes reservoirs <NUM> for multiple print fluids. Although not shown in <FIG>, reservoirs <NUM> are fluidly coupled to printheads <NUM>, such as with hoses or the like.

<FIG> is a perspective view of a printhead <NUM> in an illustrative embodiment. In this embodiment, printhead <NUM> includes a head member <NUM> and electronics <NUM>. Head member <NUM> is an elongated component that forms the jetting channels of printhead <NUM>. A typical jetting channel includes a nozzle, a pressure chamber, and a diaphragm that is driven by an actuator, such as a piezoelectric actuator. Electronics <NUM> control how the nozzles of printhead <NUM> jet droplets in response to data signals and control signals. Although not visible in <FIG>, electronics <NUM> may include one or more driver circuits configured to drive actuators (e.g., piezoelectric actuators) that contact the diaphragms of the jetting channels. Electronics <NUM> connect to a controller (e.g., jetting apparatus controller <NUM>) to receive the data signals and control signals. The controller is configured to provide the data signals and control signals to printhead <NUM> to control jetting of the individual jetting channels, to control the temperature of printhead <NUM>, etc..

The bottom surface of head member <NUM> in <FIG> includes the nozzles of the jetting channels, and represents the discharge surface <NUM> of printhead <NUM>. The top surface of head member <NUM> in <FIG> (referred to as I/O surface <NUM>) represents the Input/Output (I/O) portion for receiving one or more print fluids into printhead <NUM>, and/or conveying print fluids (e.g., fluids that are not jetted) out of printhead <NUM>. I/O surface <NUM> includes a plurality of I/O ports <NUM>-<NUM>. An I/O port <NUM>-<NUM> may comprise an inlet I/O port, which is an opening in head member <NUM> that acts as an entry point for a print fluid. An I/O port <NUM>-<NUM> may comprise an outlet I/O port, which is an opening in head member <NUM> that acts as an exit point for a print fluid. I/O ports <NUM>-<NUM> may include a hose coupling, hose barb, etc., for coupling with a hose of a reservoir, a cartridge, or the like. The number of I/O ports <NUM>-<NUM> is provided as an example, as printhead <NUM> may include other numbers of I/O ports.

Head member <NUM> includes a housing <NUM> and a plate stack <NUM>. Housing <NUM> is a rigid member made from stainless steel or another type of material. Housing <NUM> includes an access hole <NUM> that provides a passageway for electronics <NUM> to pass through housing <NUM> so that actuators may interface with (i.e., come into contact with) diaphragms of the jetting channels. Plate stack <NUM> attaches to an interface surface (not visible) of housing <NUM>. Plate stack <NUM> (also referred to as a laminate plate stack) is a series of plates that are fixed or bonded to one another to form a laminated stack. Plate stack <NUM> may include the following plates: one or more nozzle plates, one or more chamber plates, one or more restrictor plates, and a diaphragm plate. A nozzle plate includes a plurality of nozzles that are arranged in one or more rows (e.g., two rows, four rows, etc.). A chamber plate includes a plurality of openings that form the pressure chambers of the jetting channels. A restrictor plate includes a plurality of restrictors that fluidly connect the pressure chambers of the jetting channels with a manifold. A diaphragm plate is a sheet of a semi-flexible material that vibrates in response to actuation by an actuator (e.g., piezoelectric actuator).

The embodiment in <FIG> illustrates one particular configuration of a printhead <NUM>, and it is understood that other printhead configurations are considered herein that have a plurality of jetting channels.

<FIG> is a schematic diagram of jetting channels <NUM> within a printhead <NUM> in an illustrative embodiment. This diagram represents a view along a length of printhead <NUM>. A jetting channel <NUM> is a structural element within printhead <NUM> that jets or ejects a print fluid. Each jetting channel <NUM> includes a diaphragm <NUM>, a pressure chamber <NUM>, and a nozzle <NUM>. An actuator <NUM> contacts diaphragm <NUM> to control jetting from a jetting channel <NUM>. Jetting channels <NUM> may be formed in one or more rows along a length of printhead <NUM>, and each jetting channel <NUM> may have a similar configuration as shown in <FIG>.

<FIG> is another schematic diagram of a jetting channel <NUM> within a printhead <NUM> in an illustrative embodiment. The view in <FIG> is of a cross-section of a jetting channel <NUM> across a width of a portion of printhead <NUM>. Pressure chamber <NUM> is fluidly coupled to a manifold <NUM> through a restrictor <NUM>. Restrictor <NUM> controls the flow of the print fluid from manifold <NUM> to pressure chamber <NUM>. One wall of pressure chamber <NUM> is formed with diaphragm <NUM> that physically interfaces with actuator <NUM>. Diaphragm <NUM> may comprise a sheet of semi-flexible material that vibrates in response to actuation by actuator <NUM>. The print fluid flows through pressure chamber <NUM> and out of nozzle <NUM> in the form of a droplet in response to actuation by actuator <NUM>. Actuator <NUM> is configured to receive a jetting pulse, and to actuate or "fire" in response to the jetting pulse. Firing of actuator <NUM> in jetting channel <NUM> creates pressure waves in pressure chamber <NUM> that cause jetting of a droplet from nozzle <NUM>.

In another embodiment, printhead <NUM> may comprise a flow-through type of printhead. <FIG> are schematic diagrams of a jetting channel <NUM> within a flow-through printhead <NUM> in another illustrative embodiment. The view in <FIG> is of a cross-section of a jetting channel <NUM> across a width of a portion of printhead <NUM>. Pressure chamber <NUM> is fluidly coupled to a supply manifold <NUM> through a first restrictor <NUM>, and is fluidly coupled to a return manifold <NUM> through a second restrictor <NUM>. Restrictor <NUM> fluidly couples pressure chamber <NUM> with supply manifold <NUM>, and controls the flow of the print fluid into pressure chamber <NUM>. Restrictor <NUM> fluidly couples pressure chamber <NUM> to return manifold <NUM>, and controls the flow of the print fluid out of pressure chamber <NUM>. When printhead <NUM> is a "flow-through" printhead or re-circulating printhead, the print fluid may be re-circulated through printhead <NUM> past each nozzle <NUM>.

The arrow in <FIG> illustrates a flow path of a print fluid through jetting channel <NUM> in one direction. The print fluid flows from supply manifold <NUM> and into pressure chamber <NUM> through restrictor <NUM>. One wall of pressure chamber <NUM> is formed with diaphragm <NUM> that physically interfaces with actuator <NUM>, and vibrates in response to actuation by actuator <NUM>. The print fluid flows through pressure chamber <NUM> and out of nozzle <NUM> in the form of a droplet in response to actuation by actuator <NUM>. The print fluid, which is not jetted from nozzle <NUM>, flows from pressure chamber <NUM> into return manifold <NUM> through restrictor <NUM>.

The arrow in <FIG> illustrates a flow path of a print fluid within jetting channel <NUM> in a reverse direction. The print fluid flows from return manifold <NUM> and into pressure chamber <NUM> through restrictor <NUM>. The print fluid flows through pressure chamber <NUM> and out of nozzle <NUM> in the form of a droplet in response to actuation by actuator <NUM>. The print fluid, which is not jetted from nozzle <NUM>, flows from pressure chamber <NUM> into supply manifold <NUM> through restrictor <NUM>. The length of restrictors <NUM> and <NUM> may be the same to allow for a reversal of flow in this manner.

A jetting channel <NUM> as shown in <FIG> are examples to illustrate a basic structure of a jetting channel, such as the diaphragm, pressure chamber, and nozzle. Other types of jetting channels are also considered herein. For example, some jetting channels may have a pressure chamber having a different shape than is illustrated in <FIG>. Also, the position of a manifold <NUM>, a restrictor <NUM>, a diaphragm <NUM>, etc., may differ in other embodiments.

In one embodiment, a printhead <NUM> is configured to jet multiple print fluids. Print fluids may differ based on color or pigment, viscosity, density, polymers, etc. In a two-color printhead, for example, the printhead is configured to jet two different colors of print fluid (e.g., ink). In a four-color printhead, for example, the printhead is configured to jet four different colors of print fluid (e.g., ink). Thus, in a multi-fluid printhead, different subsets of jetting channels are configured to jet different print fluids.

To jet multiple print fluids, printhead <NUM> includes a plurality of manifolds each fluidly coupled to a subset of the jetting channels. <FIG> is a schematic diagram of a printhead <NUM> in an illustrative embodiment. The jetting channels <NUM> of printhead <NUM> are schematically illustrated in <FIG> as nozzles in two nozzle rows <NUM>-<NUM>. Although the nozzles are shown as staggered in <FIG>, the nozzles in the two nozzle rows <NUM>-<NUM> may be aligned in other embodiments. In this embodiment, printhead <NUM> is configured to jet one print fluid (e.g., one color) from nozzle row <NUM>, and to jet another print fluid (e.g., another color) from nozzle row <NUM>. Thus, printhead <NUM> may be considered a two-fluid printhead, or two-color printhead when jetting different colors of ink. Printhead <NUM> includes a plurality of manifolds <NUM>-<NUM>. A manifold <NUM>-<NUM> is a common fluid path in a printhead <NUM> for a plurality of jetting channels <NUM>. A manifold <NUM>-<NUM> that conveys a print fluid to a plurality of jetting channels <NUM> may also be referred to as a "supply" manifold. A manifold <NUM>-<NUM> that conveys a print fluid from a plurality of jetting channels <NUM> may be referred to as a "return" manifold, such as for a flow-through type of head. Manifold <NUM> comprises a fluid path between I/O ports <NUM>-<NUM> that is fluidly coupled to the jetting channels <NUM> in nozzle row <NUM>. Thus, a first print fluid supplied at I/O port <NUM> and/or I/O port <NUM> is conveyed through manifold <NUM> to the jetting channels <NUM> in nozzle row <NUM>. Manifold <NUM> comprises a fluid path between I/O ports <NUM>-<NUM> that is fluidly coupled to the jetting channels <NUM> in nozzle row <NUM>. Thus, a second print fluid supplied at I/O port <NUM> and/or I/O port <NUM> is conveyed through manifold <NUM> to jetting channels <NUM> in nozzle row <NUM>. Although two manifolds <NUM>-<NUM> are illustrated in <FIG>, a printhead <NUM> may include more or less manifolds as desired.

There may be multiple variations of a two-fluid printhead that are considered herein. As shown in <FIG>, manifold <NUM> is fluidly coupled to the jetting channels <NUM> in nozzle row <NUM>, and manifold <NUM> is fluidly coupled to the jetting channels <NUM> in nozzle row <NUM>. In other embodiments, manifold <NUM> may be fluidly coupled to a subset of jetting channels <NUM> in nozzle row <NUM> and nozzle row <NUM>, and manifold <NUM> may be fluidly coupled to a subset of jetting channels <NUM> in nozzle row <NUM> and nozzle row <NUM>.

<FIG> is a schematic diagram of a printhead <NUM> in another illustrative embodiment. The jetting channels <NUM> of printhead <NUM> are again schematically illustrated in <FIG> as nozzles in two nozzle rows <NUM>-<NUM>. In this embodiment, printhead <NUM> is configured to jet two different print fluids from nozzle row <NUM>, and to jet two different print fluids from nozzle row <NUM>. Thus, printhead <NUM> may be considered a two-fluid printhead or a four-fluid printhead. Printhead <NUM> includes a plurality of manifolds <NUM>-<NUM>. Manifold <NUM> comprises a fluid path from I/O port <NUM> to a first subset of jetting channels <NUM> in nozzle row <NUM>. Manifold <NUM> comprises a fluid path from I/O port <NUM> to a second subset of jetting channels <NUM> in nozzle row <NUM>. Manifold <NUM> comprises a fluid path from I/O port <NUM> to a first subset of jetting channels <NUM> in nozzle row <NUM>. Manifold <NUM> comprises a fluid path from I/O port <NUM> to a second subset of jetting channels <NUM> in nozzle row <NUM>.

There may be multiple variations of a four-fluid printhead that are considered herein. For example, jetting channels <NUM> in nozzle row <NUM> may alternate between a print fluid supplied by manifold <NUM>, and a print fluid supplied by manifold <NUM> in one embodiment. Likewise, jetting channels <NUM> in nozzle row <NUM> may alternate between a print fluid supplied by manifold <NUM>, and a print fluid supplied by manifold <NUM>.

Printhead <NUM> may also comprise an eight-fluid printhead or more in other embodiments. Printheads configured to jet four, eight, or more different print fluids are described in <CIT> and <CIT>).

<FIG> is a block diagram of a jetting control system <NUM> in an illustrative embodiment. Jetting control system <NUM> is an apparatus or collection of circuits, devices, controllers, etc., configured to control one or more printheads. In this embodiment, jetting control system <NUM> includes a jetting controller <NUM> that is communicatively coupled to one or more printheads <NUM>. One example of jetting controller <NUM> is jetting apparatus controller <NUM> as shown in <FIG>. Jetting controller <NUM> may be referred to as a print controller when implemented in a printer (e.g., continuous-feed printer, cut-sheet printer, 3D printer, etc.). Jetting control system <NUM> further includes one or more driver circuits <NUM> for a printhead <NUM>. A driver circuit <NUM> is communicatively coupled to a set of actuators (e.g., piezoelectric actuators) in a printhead <NUM>, and is configured to drive the set of actuators.

In this embodiment, jetting controller <NUM> includes a drive waveform generator <NUM>, a print data handler <NUM>, and a control signal generator <NUM>. Drive waveform generator <NUM> (also referred to as a pulse generator) comprises circuitry, logic, hardware, means, etc., configured to generate a drive waveform <NUM> for a driver circuit <NUM> in a printhead <NUM>. A drive waveform <NUM> comprises a series or train of jetting pulses (and possibly other pulses, such as non-jetting pulses) that are selectively applied as driver output signals to actuators <NUM>. Although not illustrated, drive waveform generator <NUM> may also include an amplifier circuit that amplifies the current of drive waveform <NUM>. Print data handler <NUM> comprises circuitry, logic, hardware, means, etc., configured to provide print data <NUM> to a driver circuit <NUM>. Print data handler <NUM> may include a spool, queue, buffer, or the like that stores print data, such as rasterized data, bitmaps, etc., for a print job. Print data handler <NUM> determines which print data applies to the jetting channels <NUM> controlled by driver circuit <NUM>, and provides that print data to driver circuit <NUM>. Control signal generator <NUM> comprises circuitry, logic, hardware, means, etc., configured to provide control signals <NUM> to driver circuit <NUM>. The control signals <NUM> may include gating or masking signals, a latch signal, a serial clock, etc..

One or more of the subsystems of jetting controller <NUM> may be implemented on a hardware platform comprised of analog and/or digital circuitry. One or more of the subsystems of jetting controller <NUM> may be implemented on a processor <NUM> that executes instructions stored in memory <NUM>. Processor <NUM> comprises an integrated hardware circuit configured to execute instructions, and memory <NUM> is a non-transitory computer readable storage medium for data, instructions, applications, etc., and is accessible by processor <NUM>.

Driver circuit <NUM> and actuators <NUM> may be an example of electronics <NUM> of printhead <NUM> as shown in <FIG>. Driver circuit <NUM> controls jetting for a set of jetting channels <NUM> of printhead <NUM>. More particularly, driver circuit <NUM> controls which jetting channels <NUM> fire during a jetting cycle based on the print data. Driver circuit <NUM> may comprise an integrated circuit that is fabricated on printhead <NUM>.

Actuators <NUM> are the actuating devices for jetting channels <NUM> that act to jet a droplet out of a nozzle <NUM> in response to a jetting pulse. A piezoelectric actuator, for example, converts electrical energy directly into linear motion. To jet from a jetting channel <NUM>, one or more jetting pulses of the drive waveform <NUM> are provided to an actuator <NUM>. A jetting pulse causes a deformation, physical displacement, or stroke of an actuator <NUM>, which in turn acts to deform a wall of pressure chamber <NUM> (e.g., diaphragm <NUM>) as shown in <FIG>. Deformation of the chamber wall generates pressure waves inside pressure chamber <NUM> that force a droplet from jetting channel <NUM> (when specific conditions are met). A jetting pulse is therefore able to cause a droplet to be jetted from a jetting channel <NUM> with the desired properties when the jetting channel <NUM> is at rest.

<FIG> illustrates a jetting pulse <NUM> of a drive waveform <NUM> for a printhead. The drive waveform in <FIG> is shown as an active-low signal, but may be an active-high signal in other embodiments. Jetting pulse <NUM> has a trapezoidal shape, and may be characterized by the following parameters: fall time, rise time, pulse width, and jetting amplitude. Jetting pulse <NUM> transitions from a baseline (high) voltage <NUM> to a jetting (low) voltage <NUM> along a leading edge <NUM>. The potential difference between the baseline voltage <NUM> and the jetting voltage <NUM> represents the amplitude of jetting pulse <NUM>. Jetting pulse <NUM> then transitions from jetting (low) voltage <NUM> to baseline (high) voltage <NUM> along a trailing edge <NUM>. These parameters of jetting pulse <NUM> can impact the jetting characteristics of the droplets from jetting channel <NUM> (e.g., droplet velocity and mass). For example, when the amplitude of jetting pulse <NUM> equals a target jetting amplitude (i.e., the jetting voltage) for a target pulse width, a droplet of a desired velocity and mass is jetted from a jetting channel <NUM>. A standard jetting pulse <NUM> may be selected for different types of printheads to produce droplets having a desired shape (e.g., spherical), size, velocity, etc..

The following provides an example of jetting a droplet from a jetting channel <NUM> using jetting pulse <NUM>, such as from jetting channel <NUM> in <FIG>. Jetting pulse <NUM> is initially at the baseline voltage <NUM>, and transitions from the baseline voltage <NUM> to the jetting voltage <NUM>. The leading edge <NUM> (i.e., the first slope) of jetting pulse <NUM> causes an actuator <NUM> to displace in a first direction, which enlarges pressure chamber <NUM> and generates negative pressure waves within pressure chamber <NUM>. The negative pressure waves propagate within pressure chamber <NUM> and are reflected by structural changes in pressure chamber <NUM> as positive pressure waves. The trailing edge <NUM> (i.e., the second slope) of jetting pulse <NUM> causes the actuator <NUM> to displace in an opposite direction, which reduces pressure chamber <NUM> to its original size and generates another positive pressure wave. When the timing of the trailing edge <NUM> of jetting pulse <NUM> is appropriate, the positive pressure waves created by actuator <NUM> displacing to reduce the size of pressure chamber <NUM> will combine with the reflected positive pressure waves to form a combined wave that is large enough to cause a droplet to be jetted from nozzle <NUM> of jetting channel <NUM>. Therefore, the positive pressure waves generated by the trailing edge <NUM> of jetting pulse <NUM> acts to amplify the positive pressure waves that reflect within pressure chamber <NUM> due to the leading edge <NUM> of jetting pulse <NUM>. The geometry of pressure chamber <NUM> and jetting pulse <NUM> are designed to generate a large positive pressure peak at nozzle <NUM>, which drives the print fluid through nozzle <NUM>.

In <FIG>, driver circuit <NUM> may include various sub-systems to perform its operations that are not shown. For example, driver circuit <NUM> may include shift registers (e.g., upper and lower shift registers), and registers (e.g., upper and lower registers) that store the print data. Driver circuit <NUM> may also include a switch driver that controls whether the drive waveform <NUM> is output to each individual jetting channel <NUM> based on the print data and gating signals. <FIG> is a schematic diagram of a switch driver <NUM> of driver circuit <NUM> in an illustrative embodiment. Switch driver <NUM> includes a plurality of switching elements <NUM>, which may also be referred to as transmission gates. A switching element <NUM> is associated with an individual jetting channel <NUM>, which means that an individual switching element <NUM> is electrically coupled to an actuator <NUM> (e.g., piezoelectric actuator) of a jetting channel <NUM> (which is illustrated as a capacitor). Each switching element <NUM> is also coupled to an electrical bus <NUM> that conducts the drive waveform <NUM> (Vcom). Each switching element <NUM> is configured to selectively apply the drive waveform <NUM> to its associated actuator <NUM> based on the print data and a selected gating signal. When a switching element <NUM> is "ON", the switching element <NUM> closes to form or enable a conductive path between electrical bus <NUM> and its associated actuator <NUM>, and outputs the drive waveform <NUM> to its associated actuator <NUM>. When a switching element <NUM> is "OFF", the switching element <NUM> opens to break or disable the conductive path. A switching element <NUM> may comprise transistor, a logic switch, a gate or gate array, etc., that receives input and control signals, and outputs a drive output signal (VDO) when the switch is closed.

In one embodiment, switch driver <NUM> is configured to receive a clock signal (SCK), serial data (i.e., print data), and a latch signal from jetting controller <NUM>. Switch driver <NUM> is further configured to receive a plurality of gating signals <NUM>-<NUM> (MN0-MN3) from jetting controller <NUM>. A gating signal <NUM>-<NUM> (also referred to as a mask signal) is a digital signal that triggers passage of another signal (i.e., a drive waveform) or blocks the other signal. Switch driver <NUM> further includes a selector <NUM>, which is a logic device or processing device that selects a gating signal <NUM>-<NUM> for each switching element <NUM> based on the print data. The switching elements <NUM> turn "ON" and "OFF" based on the selected gating signal <NUM>-<NUM>. For example, a switching element <NUM> may turn "ON" when the selected gating signal <NUM>-<NUM> is "LOW", and may turn "OFF" when the selected gating signal <NUM>-<NUM> is "HIGH".

The timing of when a switching element <NUM> is "ON" or "OFF" defines a time window where the drive waveform <NUM> is allowed to pass to an actuator <NUM>. For instance, when a switching element <NUM> is "ON" for a jetting channel <NUM>, the driver signal output (VDO) of the switch driver <NUM> to the actuator <NUM> of the jetting channel <NUM> is the drive waveform <NUM> (Vcom). Any drive pulses of the drive waveform <NUM> will therefore cause jetting from this jetting channel. When the switching element <NUM> is "OFF" for the jetting channel <NUM>, the driver signal output (VDO) of the switch driver <NUM> to the actuator <NUM> of the jetting channel <NUM> is a constant high or low voltage that does not cause jetting.

Switch driver <NUM> as illustrated in <FIG> is configured for two-bit print data with four gating signals <NUM>-<NUM>. However, switch driver <NUM> may be configured for three-bit print data with eight gating signals, or more in other embodiments.

Driver circuit <NUM> may be implemented in a printhead <NUM> to control jetting of a single print fluid (e.g., single color) from jetting channels <NUM>. <FIG> is a schematic diagram of a printhead <NUM> having a driver circuit <NUM> for a single print fluid. Driver circuit <NUM> controls a plurality of jetting channels <NUM> that are fluidly coupled to a common manifold <NUM>. Thus, each of the jetting channels <NUM> is configured to jet the same print fluid (e.g., same color of ink).

<FIG> is a signal diagram <NUM> for driver circuit <NUM> driving jetting channels for a single print fluid. Signal diagram <NUM> shows a serial data clock (SCK), the serial data (SD0. SD1), and latch signal (SL_n). The serial data is loaded into to upper and lower shift registers of driver circuit <NUM> based on the serial data clock, and then latched into the upper and lower registers at the rising edge of the latch signal.

Signal diagram <NUM> also shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of three jetting pulses <NUM> for a jetting period <NUM> or jetting cycle. A jetting period <NUM> comprises a time period designated for jetting by a jetting channel <NUM> for a pixel. For example, when a jetting channel <NUM> jets for an individual pixel, the jetting channel <NUM> will jet during the jetting period <NUM>. Each of the jetting pulses <NUM> on drive waveform <NUM> is configured to cause jetting at a jetting channel <NUM>, which means that the pulse width and amplitude of each pulse is configured to activate an actuator <NUM> to cause jetting of a droplet from a jetting channel <NUM>. Although three jetting pulses are used for jetting at a single pixel in this example, more or less jetting pulses may be used within a jetting period <NUM> in other examples.

Signal diagram <NUM> also shows gating signals <NUM>-<NUM> (MN0-MN3) that may be applied to switching elements <NUM> based on selection by selector <NUM>. When driver circuit <NUM> controls a single print fluid, each of the gating signals <NUM>-<NUM> are designated for that single print fluid. When a gating signal <NUM>-<NUM> is "HIGH", a switching element <NUM> is "OFF" meaning that drive waveform <NUM> is blocked from an actuator <NUM>. When a gating signal <NUM>-<NUM> is "LOW", a switching element <NUM> is "ON" meaning that drive waveform <NUM> is allowed to pass to an actuator <NUM>. Signal diagram <NUM> also shows the driver output signals <NUM>-<NUM> (VDO) that are provided or applied to an actuator <NUM> in response to the respective gating signals <NUM>-<NUM>.

Gating signal <NUM> (MNO) is always "HIGH", and acts to keep a switching element <NUM> off during a jetting period <NUM>. Thus, the corresponding driver output signal <NUM> to an actuator <NUM> of a jetting channel <NUM> is a constant high voltage when gating signal <NUM> (MNO) is selected. Because there is no jetting pulse <NUM> on the driver output signal <NUM>, there will be no jetting from the jetting channel. Gating signal <NUM> (MN1) is "LOW" for a time window that allows one jetting pulse <NUM> from drive waveform <NUM> to pass on driver output signal <NUM> to an actuator <NUM> of a jetting channel <NUM>. The single jetting pulse <NUM> will actuate the actuator <NUM> of the jetting channel <NUM> once, resulting in jetting of one droplet from the jetting channel <NUM>. Gating signal <NUM> (MN2) is "LOW" for a time window that allows two jetting pulses <NUM> from drive waveform <NUM> to pass on driver output signal <NUM> to an actuator <NUM> of a jetting channel <NUM>. The two jetting pulses <NUM> will actuate the actuator <NUM> of the jetting channel <NUM> twice, resulting in jetting of two droplets from the jetting channel <NUM>. Gating signal <NUM> (MN3) is "LOW" for a time window that allows three jetting pulses <NUM> from drive waveform <NUM> to pass on driver output signal <NUM> to an actuator <NUM> of a jetting channel <NUM>. The three jetting pulses <NUM> will actuate the actuator <NUM> of the jetting channel <NUM> three times, resulting in jetting of three droplets from the jetting channel <NUM>.

As is evident in <FIG>, gating signals <NUM>-<NUM> control how switch driver <NUM> selectively opens and closes a switching element <NUM> to control how jetting pulses <NUM> are or are not applied to jetting channels <NUM>. Based on the print data, selector <NUM> selects one of the gating signals <NUM>-<NUM> for each jetting channel <NUM>. For example, when the print data (SD0 and SD1) for a jetting channel <NUM> has a value of "<NUM>", selector <NUM> may select gating signal <NUM> (MN0) so that no jetting occurs from the jetting channel <NUM>. When the print data has a value of "<NUM>", selector <NUM> may select gating signal <NUM> (MN1) so that one droplet is jetted from the jetting channel <NUM>. When the print data has a value of "<NUM>", selector <NUM> may select gating signal <NUM> (MN2) so that two droplets are jetted from the jetting channel <NUM>. When the print data has a value of "<NUM>", selector <NUM> may select gating signal <NUM> (MN3) so that three droplets are jetted from the jetting channel <NUM>. This allows for grayscale jetting from each of the jetting channels <NUM> for the single print fluid.

In one embodiment, driver circuit <NUM> may be implemented in a printhead <NUM> to control jetting of multiple print fluids (e.g., multiple colors) from jetting channels <NUM>. Previously, to jet two different print fluids, two driver circuits would be implemented in a printhead. One of the driver circuits would control the jetting channels for one of the print fluids, and the other driver circuit would control the jetting channels for the other print fluid. To jet four different print fluids, four driver circuits would be implemented. In the embodiments below, a single driver circuit <NUM> may be used to control jetting of multiple print fluids.

<FIG> is a schematic diagram of a printhead <NUM> having a driver circuit <NUM> for multiple print fluids in an illustrative embodiment. Printhead <NUM> is shown as including a first subset <NUM> of jetting channels <NUM>, and a second subset <NUM> of jetting channels <NUM>. The first subset <NUM> of jetting channels <NUM> is configured to jet a first print fluid <NUM> (e.g., one color of ink). Thus, the jetting channels <NUM> in the first subset <NUM> are fluidly coupled to a common manifold <NUM> for the first print fluid <NUM>. The second subset <NUM> of jetting channels <NUM> is configured to jet a second print fluid <NUM> (e.g., another color of ink). Thus, the jetting channels <NUM> in the second subset <NUM> are fluidly coupled to a common manifold <NUM> for the second print fluid <NUM>.

<FIG> are flow charts illustrating a method <NUM> of driving jetting channels for multiple print fluids in an illustrative embodiment. The steps of method <NUM> will be described with reference to jetting controller <NUM> and driver circuit <NUM> in <FIG>, but those skilled in the art will appreciate that method <NUM> may be performed in other systems or circuits. Also, the steps of the flow charts described herein are not all inclusive and may include other steps not shown, and the steps may be performed in an alternative order.

In <FIG>, drive waveform generator <NUM> generates a drive waveform <NUM> comprising jetting pulses that are provisioned, pre-determined, or selected for the different print fluids (step <NUM>). Different print fluids may jet differently from a jetting channel <NUM> in response to a jetting pulse. For example, a lighter-color ink (e.g., white) may jet differently than a darker color of ink (e.g., black) in response to the same jetting pulse. Thus, in one embodiment, the jetting pulses on the drive waveform <NUM> are each provisioned for a specific print fluid. In other words, when a jetting pulse is provisioned for a specific print fluid, the characteristics of the jetting pulse may be optimized for jetting that print fluid with the desired droplet properties (e.g., shape, size/mass, velocity, etc.).

<FIG> illustrates drive waveform <NUM> in an illustrative embodiment. In this embodiment, drive waveform <NUM> includes jetting pulses <NUM> that are provisioned for a first print fluid <NUM>, and jetting pulses <NUM> that are provisioned for a second print fluid <NUM>. Within a jetting period <NUM>, drive waveform <NUM> is shown with one jetting pulse <NUM> for the first print fluid <NUM>, and one jetting pulse <NUM> for the second print fluid <NUM>. However, there may be multiple jetting pulses <NUM> for the first print fluid <NUM>, and multiple jetting pulses <NUM> for the second print fluid <NUM> in the jetting period <NUM> in other embodiments. Jetting pulse <NUM> occupies a first time slot <NUM> in the jetting period <NUM>, and jetting pulse <NUM> occupies a second time slot <NUM> in the jetting period <NUM>. For example, if the jetting period <NUM> is <NUM>/<NUM>,<NUM> of a second, then time slots <NUM>-<NUM> may each be <NUM>/<NUM>,<NUM> of a second. Drive waveform <NUM> may include additional jetting pulses provisioned for additional print fluids in other embodiments.

Jetting pulses <NUM>-<NUM> may have different characteristics optimized for their respective print fluids. <FIG> illustrates drive waveform <NUM> in another illustrative embodiment. As shown in this example, jetting pulses <NUM>-<NUM> may have different jetting amplitudes that are each provisioned based their respective print fluids. In this embodiment, jetting pulse <NUM> has a jetting amplitude <NUM> that is less than the jetting amplitude <NUM> of jetting pulse <NUM>. However, jetting pulses <NUM>-<NUM> may have other different characteristics, such as fall time, rise time, pulse width, etc., that are optimized for a particular print fluid.

In <FIG>, control signal generator <NUM> designates or assigns one or more gating signals <NUM>-<NUM> for jetting each of the print fluids (step <NUM>). As described above, a gating signal <NUM>-<NUM> is used to control the driver output signal (VDO) to a jetting channel <NUM> (e.g., one or more jetting pulses, no jetting pulse, etc.). In the description in <FIG>, the gating signals <NUM>-<NUM> were used to define greyscale levels in a jetting channel <NUM> for a single print fluid. In this embodiment, the gating signals <NUM>-<NUM> are used to control jetting of multiple print fluids. Thus, a gating signal (or more than one gating signal) is designated for jetting a particular print fluid. In a two-bit example, there are four gating signals <NUM>-<NUM> (MN0-MN3), and control signal generator <NUM> may assign one gating signal (e.g., MN1) to the first print fluid <NUM>, and another gating signal (e.g., MN2) to the second print fluid <NUM>. When a gating signal is assigned or designated to a print fluid, the gating signal is used exclusively for jetting that print fluid. For example, if gating signal MN1 is assigned to a first color of ink, then gating signal MN1 is used exclusively for jetting the first color of ink. If gating signal MN2 is assigned to a second color of ink, then gating signal MN2 is used exclusively for jetting the second color of ink. The gating signals <NUM>-<NUM> assigned to a print fluid for jetting represent "active" gating signals for jetting by a jetting channel <NUM> during a jetting period <NUM>. An active gating signal will allow the drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Control signal generator <NUM> also defines one or more no-jetting or inactive gating signals (e.g., MN0) that do not allow the drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>.

Each gating signal <NUM>-<NUM>, that is assigned to a particular print fluid, is configured or formatted with active time windows that correspond (in time) with one or more pulses of drive waveform <NUM>. A gating signal <NUM>-<NUM> is a digital signal that has pulses which trigger passage of the drive waveform <NUM> to an actuator <NUM>. These pulses that trigger passage of the drive waveform <NUM> are considered active time windows. For example, an active time window may be when a gating signal <NUM>-<NUM> is set to "LOW". <FIG> is a signal diagram <NUM> illustrating gating signals <NUM>-<NUM> in an illustrative embodiment. Assume for this example that jetting pulse <NUM> is provisioned for a first print fluid <NUM>, and gating signal <NUM> (MN1) is designated for jetting the first print fluid <NUM>. Control signal generator <NUM> may configure gating signal <NUM> with active time windows <NUM> that correspond with the jetting pulses <NUM> for the first print fluid <NUM>. Within a jetting period <NUM>, an active time window <NUM> for gating signal <NUM> corresponds with the time slot <NUM> of jetting pulse <NUM>. Further assume for this example that jetting pulse <NUM> is provisioned for a second print fluid <NUM>, and gating signal <NUM> (MN2) is designated for jetting the second print fluid <NUM>. Control signal generator <NUM> may configure gating signal <NUM> with active time windows <NUM> that correspond with the jetting pulses <NUM> for the second print fluid <NUM>. Within a jetting period <NUM>, an active time window <NUM> for gating signal <NUM> corresponds with the time slot <NUM> of jetting pulse <NUM>.

In <FIG>, jetting controller <NUM> sends, transmits, or provides the drive waveform <NUM>, gating signals <NUM>-<NUM> (along with other control signals <NUM>), and print data <NUM> to driver circuit <NUM> (step <NUM>). The gating signals <NUM>-<NUM> include one or more active gating signals designated for jetting the first print fluid <NUM>, and one or more active gating signals designated for jetting the second print fluid <NUM>. However, more gating signals for additional print fluids (e.g., a third print fluid, a fourth print fluid, etc.) may also be sent by jetting controller <NUM>.

In <FIG>, driver circuit <NUM> receives the drive waveform <NUM>, gating signals <NUM>-<NUM>, and print data <NUM> (step <NUM>). Assume for this example that of the gating signals <NUM>-<NUM> received from jetting controller <NUM>, gating signal <NUM> is an active gating signal designated for jetting the first print fluid <NUM>, and gating signal <NUM> is an active gating signal designated for jetting the second print fluid <NUM> as shown in <FIG>. Driver circuit <NUM> then selectively applies the drive waveform <NUM> to the jetting channels <NUM> as follows. Driver circuit <NUM> selectively applies jetting pulses from drive waveform <NUM> to the first subset <NUM> of jetting channels <NUM> based on active gating signal <NUM> to jet the first print fluid <NUM> (step <NUM>). For example, driver circuit <NUM> may select a gating signal for each of the jetting channels <NUM> of the first subset <NUM> based on the print data for those jetting channels <NUM>. When the selected gating signal is active gating signal <NUM> and drive waveform <NUM> is configured as shown in <FIG>, driver circuit <NUM> will apply a first jetting pulse <NUM> from drive waveform <NUM> to that jetting channel <NUM>, and will block the second jetting pulse <NUM>. When the selected gating signal is an inactive gating signal <NUM>, driver circuit <NUM> will block the drive waveform <NUM> from being applied to that jetting channel <NUM>.

Driver circuit <NUM> selectively applies jetting pulses from drive waveform <NUM> to the second subset <NUM> of jetting channels <NUM> based on active gating signal <NUM> to jet the second print fluid <NUM> (step <NUM>). For example, driver circuit <NUM> may select a gating signal for each of the jetting channels <NUM> of the second subset <NUM> based on the print data for those jetting channels <NUM>. When the selected gating signal is active gating signal <NUM> and drive waveform <NUM> is configured as shown in <FIG>, driver circuit <NUM> will apply a second jetting pulse <NUM> from drive waveform <NUM> to that jetting channel <NUM>, and will block the first jetting pulse <NUM>. When the selected gating signal is an inactive gating signal <NUM>, driver circuit <NUM> will block the drive waveform <NUM> from being applied to that jetting channel <NUM>.

One technical benefit of the jetting control system <NUM> described above is that driver circuit <NUM> may be used for multiple print fluids in a printhead <NUM>. A typical driver circuit <NUM> was used to drive jetting channels <NUM> of a single print fluid. However, a drive waveform <NUM> as described above may have different jetting pulses provisioned for different print fluids, and gating signals are assigned to specific print fluids. Thus, driver circuit <NUM> is able to use the gating signals to apply the print-fluid-specific jetting pulses to the appropriate jetting channels <NUM> to jet different print fluids.

The following provides a further description of how driver circuit <NUM> selectively applies jetting pulses to jetting channels <NUM> in one embodiment. <FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of jetting pulses <NUM>-<NUM> for a jetting period <NUM>. Jetting pulse <NUM> is provisioned for a first print fluid <NUM>, and jetting pulse <NUM> is provisioned for a second print fluid <NUM>. In this embodiment, jetting pulse <NUM> has a jetting amplitude that is less than the jetting amplitude of jetting pulse <NUM>. However, jetting pulses <NUM>-<NUM> may have other different characteristics that are optimized for a particular print fluid in other embodiments.

Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a jetting pulse <NUM>-<NUM> on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM> for the first print fluid <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM> for the second print fluid <NUM>. Other gating signals, such as MN3, may be ignored in this embodiment.

<FIG> is a flow chart illustrating a method <NUM> of selectively applying jetting pulses from drive waveform <NUM> to jetting channels <NUM> in an illustrative embodiment. For a jetting period <NUM> (as shown in <FIG>), driver circuit <NUM> obtains the print data for the jetting channels <NUM> (step <NUM>), such as for the first subset <NUM> of jetting channels <NUM> and the second subset <NUM> of jetting channels <NUM>. For each jetting period <NUM>, driver circuit <NUM> will use the print data to select gating signals for the individual jetting channels <NUM>. <FIG> is a schematic diagram of switch driver <NUM> of driver circuit <NUM> in an illustrative embodiment. As in <FIG>, switch driver <NUM> includes a plurality of switching elements <NUM> each associated with an individual jetting channel <NUM>. In this embodiment, a subset <NUM> of the switching elements <NUM> are associated with the first subset <NUM> of jetting channels <NUM> for the first print fluid <NUM> (see <FIG>), and a subset <NUM> of the switching elements <NUM> are associated with the second subset <NUM> of jetting channels <NUM> for the second print fluid <NUM>. The switching elements <NUM> in subset <NUM> are each communicatively (e.g., electrically) coupled to an actuator <NUM> of a jetting channel <NUM> configured to jet the first print fluid <NUM>. The switching elements <NUM> in subset <NUM> are each communicatively coupled to an actuator <NUM> of a jetting channel <NUM> configured to jet the second print fluid <NUM>. Each switching element <NUM> is configured to selectively apply the drive waveform <NUM> to its associated actuator <NUM> based on the print data.

For the present jetting period <NUM>, driver circuit <NUM> (through selector <NUM>) selects a gating signal <NUM>-<NUM> for each of the jetting channels <NUM> based on the print data (step <NUM> of <FIG>). In the above example, gating signal <NUM> is configured as an inactive gating signal (e.g., set to "HIGH"), gating signal <NUM> is configured as an active gating signal designated for jetting the first print fluid <NUM>, and gating signal <NUM> is configured as an active gating signal designated for jetting the second print fluid <NUM>. Thus, selector <NUM> selects either inactive gating signal <NUM> or active gating signal <NUM> for the first subset <NUM> of jetting channels <NUM> configured to jet the first print fluid <NUM>, and selects either inactive gating signal <NUM> or active gating signal <NUM> for the second subset <NUM> of jetting channels <NUM> configured to jet the second print fluid <NUM>.

For each jetting channel <NUM> controlled by driver circuit <NUM>, it may perform the following. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the active gating signal <NUM> designated for jetting the first print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal (VDO) to the actuator <NUM> of the jetting channel <NUM> (step <NUM>), and blocks jetting pulse <NUM>. As shown in <FIG>, the active gating signal <NUM> (MN1) for the first print fluid <NUM> is "LOW" for a time window <NUM> that corresponds with jetting pulse <NUM> of drive waveform <NUM>. Thus, a switching element <NUM> for this jetting channel <NUM> will be "ON" when the active gating signal <NUM> is low, and the driver output signal <NUM> will include jetting pulse <NUM> and not jetting pulse <NUM>.

In <FIG>, when the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the second print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal (VDO) to the actuator <NUM> of the jetting channel <NUM> (step <NUM>), and blocks jetting pulse <NUM>. As shown in <FIG>, the active gating signal <NUM> (MN2) for the second print fluid <NUM> is "LOW" for a time window <NUM> that corresponds with jetting pulse <NUM> of drive waveform <NUM>. Thus, a switching element <NUM> for this jetting channel <NUM> will be "ON" when the active gating signal <NUM> is low, and the driver output signal <NUM> will include jetting pulse <NUM> and not jetting pulse <NUM>.

In <FIG>, when the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the inactive gating signal <NUM>, driver circuit <NUM> outputs no jetting pulse on the driver output signal (VDO) to the actuator <NUM> of the jetting channel <NUM> (step <NUM>). As shown in <FIG>, the inactive gating signal <NUM> (MN0) is set at a constant voltage. Thus, a switching element <NUM> for this jetting channel <NUM> will be "OFF", and the driver output signal <NUM> will include no jetting pulse.

In looking at <FIG>, jetting pulse <NUM> leads jetting pulse <NUM> in the jetting period <NUM> of drive waveform <NUM>. It may be desirable for jetting channels <NUM> for the first print fluid <NUM> to jet concurrently with the jetting channels <NUM> for the second print fluid <NUM>. Thus, driver circuit <NUM> may delay the first jetting pulses <NUM> applied to the first subset <NUM> of jetting channels <NUM> (optional step <NUM>), in one embodiment. For example, driver circuit <NUM> may delay the first jetting pulse <NUM> on driver output signal <NUM> to align time-wise with the second jetting pulse <NUM> on driver output signal <NUM>. By delaying a first jetting pulse <NUM>, jetting of the first print fluid <NUM> from the first subset <NUM> of jetting channels <NUM> is concurrent or substantially concurrent with jetting of the second print fluid <NUM> from the second subset <NUM> of jetting channels <NUM>.

The above embodiment described a driver circuit <NUM> that drives jetting channels <NUM> for two different print fluids. The jetting channels <NUM> may be arranged in various ways. For example, the jetting channels <NUM> for the first print fluid <NUM> and the jetting channels <NUM> for the second print fluid <NUM> may form a single row <NUM> of nozzles, as shown in <FIG>. Thus, driver circuit <NUM> is able to drive jetting channels <NUM> for two different print fluids arranged in a single row <NUM> of nozzles. In another embodiment, the jetting channels <NUM> for the first print fluid <NUM> may form at least part of a first row <NUM> of nozzles, and the jetting channels <NUM> for the second print fluid <NUM> may form at least part of a second row <NUM> of nozzles, as shown in <FIG>.

The above embodiments described a two-bit driver circuit <NUM>. However, driver circuit <NUM> may comprise a three-bit driver, a four-bit driver, etc., in other embodiments. In a three-bit driver, for example, there may be eight gating signals. When a driver circuit <NUM> drives jetting channels <NUM> for two different print fluids and there are eight gating signals, more than one gating signal may be designated for jetting each of the print fluids. Thus, different greyscale levels may be produced for each of the print fluids in a similar manner as described in <FIG>.

Further, when a three-bit driver is implemented, driver circuit <NUM> may drive jetting channels <NUM> for four (or more) different print fluids <NUM>-<NUM> in two rows <NUM>-<NUM> of nozzles as shown in <FIG>, in a single row of nozzles, or more rows of nozzles. <FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of jetting pulses <NUM>-<NUM> for a jetting period <NUM>. Jetting pulse <NUM> is provisioned for a first print fluid <NUM>, jetting pulse <NUM> is provisioned for a second print fluid <NUM>, jetting pulse <NUM> is provisioned for a third print fluid <NUM>, and jetting pulse <NUM> is provisioned for a fourth print fluid <NUM>. In this embodiment, it may be assumed that jetting pulses <NUM>-<NUM> have different characteristics that are optimized for a particular print fluid.

Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a jetting pulse <NUM>-<NUM> on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM> for the first print fluid <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM> for the second print fluid <NUM>. Gating signal <NUM> (MN3) is an active gating signal designated for jetting the third print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM> for the third print fluid <NUM>. Gating signal <NUM> (MN4) is an active gating signal designated for jetting the fourth print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM> for the fourth print fluid <NUM>. Other gating signals, such as MN5-MN7, may be ignored in this embodiment.

For each jetting channel <NUM> controlled by driver circuit <NUM>, it may perform the following. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the active gating signal <NUM> designated for jetting the first print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks the other jetting pulses <NUM>-<NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the second print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks jetting pulses <NUM> and <NUM>-<NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the third print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks jetting pulses <NUM>-<NUM> and <NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the fourth print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks jetting pulses <NUM>-<NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the inactive gating signal <NUM>, driver circuit <NUM> outputs no jetting pulse on the driver output signal to the actuator <NUM> of the jetting channel <NUM>.

When driving jetting channels <NUM> for eight or more different print fluids, additional driver circuits <NUM> may be implemented that each drive four of the different print fluids as described above.

In the above embodiments, the drive waveform <NUM> included jetting pulses provisioned for two, four, or more different print fluids. In other embodiments, a jetting pulse (or multiple jetting pulses) may be shared to jet different print fluids. However, one or more non-jetting pulses (also referred to as pre-pulses or tickle pulses) may be included on the drive waveform <NUM> along with the jetting pulses. A non-jetting pulse is a pulse having a pulse width and/or amplitude that does not cause jetting of a droplet from a jetting channel <NUM>. A non-jetting pulse may cause a partial deformation or physical displacement of an actuator <NUM>, but the displacement is not sufficient to eject a droplet from a nozzle <NUM>. Although a non-jetting pulse does not cause jetting, when one or more non-jetting pulses are applied to an actuator <NUM> of a jetting channel <NUM> along with a jetting pulse, the non-jetting pulse can affect jetting from the jetting channel <NUM> in response to the jetting pulse. Thus, driver circuit <NUM> can control jetting of different print fluids using non-jetting pulses in conjunction with jetting pulses.

<FIG> are flow charts illustrating a method <NUM> of driving jetting channels for multiple print fluids in an illustrative embodiment. Drive waveform generator <NUM> (see <FIG>) generates a drive waveform <NUM> comprising non-jetting pulses and jetting pulses (step <NUM>). <FIG> illustrates drive waveform <NUM> in an illustrative embodiment. In this embodiment, drive waveform <NUM> includes non-jetting pulses <NUM> and jetting pulses <NUM>. Within a jetting period <NUM>, drive waveform <NUM> is shown with one non-jetting pulse <NUM> and one jetting pulse <NUM>. However, there may be multiple non-jetting pulses <NUM>, and multiple jetting pulses <NUM> in the jetting period <NUM> in other embodiments. Non-jetting pulse <NUM> occupies a first time slot <NUM> in the jetting period <NUM>, and jetting pulse <NUM> occupies a second time slot <NUM> in the jetting period <NUM>.

In <FIG>, control signal generator <NUM> designates or assigns one or more gating signals <NUM>-<NUM> for jetting each of the print fluids (step <NUM>). As above, each gating signal <NUM>-<NUM>, that is assigned to a particular print fluid, is configured or formatted with active time windows that correspond (in time) with one or more pulses of drive waveform <NUM>. <FIG> is a signal diagram <NUM> illustrating gating signals <NUM>-<NUM> in an illustrative embodiment. Assume for this example that gating signal <NUM> (MN1) is designated for jetting the first print fluid <NUM>. Control signal generator <NUM> may configure gating signal <NUM> with active time windows <NUM> that correspond with the non-jetting pulses <NUM> and the jetting pulses <NUM>. Further assume for this example that gating signal <NUM> (MN2) is designated for jetting the second print fluid <NUM>. Control signal generator <NUM> may configure gating signal <NUM> with active time windows <NUM> that correspond with the jetting pulses <NUM>.

In <FIG>, driver circuit <NUM> receives the drive waveform <NUM>, gating signals <NUM>-<NUM>, and print data <NUM> (step <NUM>). Assume for this example that of the gating signals <NUM>-<NUM> received from jetting controller <NUM>, gating signal <NUM> is an active gating signal designated for jetting the first print fluid <NUM>, and gating signal <NUM> is an active gating signal designated for jetting the second print fluid <NUM> as shown in <FIG>. Driver circuit <NUM> then selectively applies the drive waveform <NUM> to the jetting channels as follows. Driver circuit <NUM> selectively applies non-jetting pulses <NUM> and jetting pulses <NUM> from drive waveform <NUM> to the first subset <NUM> of jetting channels <NUM> based on active gating signal <NUM> to jet the first print fluid <NUM> (step <NUM>). For example, driver circuit <NUM> may select a gating signal for each of the jetting channels <NUM> of the first subset <NUM> based on the print data for those jetting channels <NUM>. When the selected gating signal is active gating signal <NUM> and drive waveform <NUM> is configured as shown in <FIG>, driver circuit <NUM> will apply a non-jetting pulse <NUM> and a jetting pulse <NUM> from drive waveform <NUM> to that jetting channel <NUM>. When the selected gating signal is an inactive gating signal <NUM>, driver circuit <NUM> will not apply the drive waveform <NUM> to that jetting channel <NUM>.

Driver circuit <NUM> selectively applies jetting pulses <NUM> from drive waveform <NUM> to the second subset <NUM> of jetting channels <NUM> based on active gating signal <NUM> to jet the second print fluid <NUM> (step <NUM>). For example, driver circuit <NUM> may select a gating signal for each of the jetting channels <NUM> of the second subset <NUM> based on the print data for those jetting channels <NUM>. When the selected gating signal is active gating signal <NUM> and drive waveform <NUM> is configured as shown in <FIG>, driver circuit <NUM> will apply a jetting pulse <NUM> from drive waveform <NUM> to that jetting channel <NUM>. When the selected gating signal is an inactive gating signal <NUM>, driver circuit <NUM> will not apply the drive waveform <NUM> to that jetting channel <NUM>.

One technical benefit of the jetting control system <NUM> described above is that driver circuit <NUM> may be used for multiple print fluids in a printhead <NUM>. And, the jetting channels <NUM> for the different print fluids will jet concurrently or substantially concurrently because the same jetting pulse <NUM> is applied to the jetting channels <NUM>. Yet, the non-jetting pulse <NUM> in the drive waveform <NUM> allows for different jetting characteristics (e.g., droplet velocity, mass, etc.) from jetting channels <NUM> of different print fluids even though a common jetting pulse <NUM> is applied to jetting channels <NUM>.

The following provides a further description of how driver circuit <NUM> selectively applies non-jetting pulses and jetting pulses to jetting channels <NUM> in one embodiment. <FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of pulses for a jetting period <NUM>. Non-jetting pulse <NUM> leads jetting pulse <NUM> in the jetting period <NUM> of drive waveform <NUM>. Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a pulse on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes an active time window <NUM> that corresponds with the non-jetting pulse <NUM> and the jetting pulse <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM>. Other gating signals, such as MN3, may be ignored in this embodiment.

<FIG> is a flow chart illustrating a method <NUM> of selectively applying pulses from drive waveform <NUM> to jetting channels <NUM> in an illustrative embodiment. For a jetting period <NUM> (as shown in <FIG>), driver circuit <NUM> obtains the print data for the jetting channels <NUM> (step <NUM>), such as for the first subset <NUM> of jetting channels <NUM> and the second subset <NUM> of jetting channels <NUM>. For each jetting period <NUM>, driver circuit <NUM> will use the print data to select gating signals for the individual jetting channels <NUM>. For the present jetting period <NUM>, driver circuit <NUM> (through selector <NUM> in <FIG>) selects a gating signal <NUM>-<NUM> for each of the jetting channels <NUM> based on the print data (step <NUM>). In the above example, gating signal <NUM> is configured as an inactive gating signal (e.g., set to "HIGH"), gating signal <NUM> is configured as an active gating signal designated for jetting the first print fluid <NUM>, and gating signal <NUM> is configured as an active gating signal designated for jetting the second print fluid <NUM>. Thus, selector <NUM> selects either inactive gating signal <NUM> or active gating signal <NUM> for the first subset <NUM> of jetting channels <NUM> configured to jet the first print fluid <NUM>, and selects either inactive gating signal <NUM> or active gating signal <NUM> for the second subset <NUM> of jetting channels <NUM> configured to jet the second print fluid <NUM>.

For each jetting channel <NUM> controlled by driver circuit <NUM>, it may perform the following. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the active gating signal <NUM> designated for jetting the first print fluid <NUM>, driver circuit <NUM> outputs non-jetting pulse <NUM> (or multiple instances of nonjetting pulse <NUM>) and jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal (VDO) to the actuator <NUM> of the jetting channel <NUM> (step <NUM>). As shown in <FIG>, the active gating signal <NUM> (MN1) for the first print fluid <NUM> is "LOW" for a time window <NUM> that corresponds with a non-jetting pulse <NUM> and a jetting pulse <NUM> of drive waveform <NUM>. Thus, a switching element <NUM> for this jetting channel <NUM> will be "ON" when the active gating signal <NUM> is low, and the driver output signal <NUM> will include non-jetting pulse <NUM> and jetting pulse <NUM>.

In <FIG>, when the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the second print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> (or multiple instances of jetting pulse <NUM>) from drive waveform <NUM> as the driver output signal (VDO) to the actuator <NUM> of the jetting channel <NUM> (step <NUM>), and blocks non-jetting pulse <NUM>. As shown in <FIG>, the active gating signal <NUM> (MN2) for the second print fluid <NUM> is "LOW" for a time window <NUM> that corresponds with a jetting pulse <NUM> of drive waveform <NUM>. Thus, a switching element <NUM> for this jetting channel <NUM> will be "ON" when the active gating signal <NUM> is low, and the driver output signal <NUM> will include jetting pulse <NUM> but will not include non-jetting pulse <NUM>.

In <FIG>, when the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the inactive gating signal <NUM>, driver circuit <NUM> outputs no pulses on the driver output signal (VDO) to the actuator <NUM> of the jetting channel <NUM> (step <NUM>). As shown in <FIG>, the inactive gating signal <NUM> (MN0) is set at a constant voltage. Thus, a switching element <NUM> for this jetting channel <NUM> will be "OFF", and the driver output signal <NUM> will include no pulses from drive waveform <NUM>.

When a non-jetting pulse <NUM> is applied to a jetting channel <NUM> preceding a jetting pulse <NUM>, the jetting characteristics can be altered. To illustrate this, <FIG> illustrates the response of a jetting channel <NUM> to a jetting pulse <NUM>. In this example, drive waveform <NUM> includes a jetting pulse <NUM> that is applied to an actuator <NUM> of a jetting channel <NUM>. Line <NUM> represents volume displacement of a print fluid at a nozzle <NUM> of the jetting channel <NUM> in response to the jetting pulse <NUM>. When the actuator <NUM> displaces in response to jetting pulse <NUM>, pressure waves are created within the pressure chamber <NUM> that resonate or absorb at a characteristic frequency. This characteristic frequency is determined by the geometry of the pressure chamber <NUM> (and other structures of a jetting channel <NUM>) and their associated fluidic properties, and is referred to as the resonant frequency or Helmholtz frequency of a jetting channel <NUM>. The pressure waves within the pressure chamber <NUM> cause the print fluid to move at the nozzle <NUM>. When the pressure or jetting energy is sufficient from the jetting pulse <NUM>, the print fluid will be ejected from the nozzle <NUM> as indicated at volume displacement peak <NUM>. <FIG> also illustrates the resonant cycle <NUM> corresponding with the resonant frequency of the jetting channel <NUM> in response to jetting pulse <NUM>.

<FIG> illustrates the response of a jetting channel <NUM> to a non-jetting pulse <NUM> and a jetting pulse <NUM> in an illustrative embodiment. In this embodiment, drive waveform <NUM> includes a non-jetting pulse <NUM> and jetting pulse <NUM> that are applied to an actuator <NUM> of a jetting channel <NUM>. Line <NUM> represents volume displacement of a print fluid at a nozzle <NUM> of the jetting channel <NUM> in response to the non-jetting pulse <NUM> and the jetting pulse <NUM>. Non-jetting pulse <NUM> and jetting pulse <NUM> are in the same voltage direction <NUM>. Non-jetting pulse <NUM> and jetting pulse <NUM> each change voltage levels by transitioning from a baseline voltage <NUM> in a positive or negative voltage direction. In this embodiment, non-jetting pulse <NUM> and jetting pulse <NUM> both transition from the baseline voltage <NUM> in a negative voltage direction (but may be in the positive voltage direction in other embodiments).

Non-jetting pulse <NUM> also has in-phase timing with the resonant frequency of the jetting channel <NUM>. In other words, the timing of nonjetting pulse <NUM> on drive waveform <NUM> with respect to jetting pulse <NUM> is such that pressure waves created by displacement of an actuator <NUM> in response to the non-jetting pulse <NUM> are in-phase with pressure waves created by displacement of the actuator <NUM> in response to the jetting pulse <NUM>. <FIG> illustrates the non-jetting cycle <NUM> of pressure waves within the jetting channel <NUM> in response to non-jetting pulse <NUM>. As is evident, pressure waves created by non-jetting pulse <NUM> are in-phase with pressure waves created by jetting pulse <NUM>. A non-jetting pulse <NUM> that is in-phase increases the jetting energy at the jetting channel <NUM>, and increases droplet mass and velocity. Thus, the volume displacement peak <NUM> is higher than when a jetting pulse <NUM> is applied alone. In <FIG>, when the active gating signal <NUM> (MN1) for the first print fluid <NUM> is selected, the driver output signal <NUM> will include non-jetting pulse <NUM> and jetting pulse <NUM>. When the active gating signal <NUM> (MN2) for the second print fluid <NUM> is selected, and the driver output signal <NUM> will include jetting pulse <NUM> but will not include non-jetting pulse <NUM>. Because the non-jetting pulse <NUM> has the same voltage direction as the jetting pulse <NUM> and is in-phase, the jetting energy at a jetting channel <NUM> for the first print fluid <NUM> will be higher than the jetting energy at a jetting channel <NUM> for the second print fluid <NUM>.

<FIG> illustrates the response of a jetting channel <NUM> to a non-jetting pulse <NUM> and a jetting pulse <NUM> in an illustrative embodiment. Line <NUM> represents volume displacement of a print fluid at a nozzle <NUM> of the jetting channel <NUM> in response to the non-jetting pulse <NUM> and the jetting pulse <NUM>. In this embodiment, non-jetting pulse <NUM> and jetting pulse <NUM> are in opposite voltage directions <NUM>-<NUM>. For example, non-jetting pulse <NUM> transitions from the baseline voltage <NUM> in a positive voltage direction, and jetting pulse <NUM> transitions from the baseline voltage <NUM> in a negative voltage direction. Non-jetting pulse <NUM> has out-of-phase timing with the resonant frequency of the jetting channel <NUM>. In other words, the timing of nonjetting pulse <NUM> on drive waveform <NUM> with respect to jetting pulse <NUM> is such that pressure waves created by displacement of an actuator <NUM> in response to the non-jetting pulse <NUM> are out-of-phase with pressure waves created by displacement of the actuator <NUM> in response to the jetting pulse <NUM>. <FIG> illustrates the non-jetting cycle <NUM> of pressure waves within the jetting channel <NUM> in response to non-jetting pulse <NUM>. As is evident, pressure waves created by non-jetting pulse <NUM> are out-of-phase with pressure waves created by jetting pulse <NUM>, such as by <NUM> degrees. A non-jetting pulse <NUM> that is in the opposite voltage direction and is out-of-phase decreases the jetting energy at the jetting channel <NUM>, and decreases droplet mass and velocity. Thus, the volume displacement peak <NUM> is lower than when a jetting pulse <NUM> is applied alone.

<FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of pulses for a jetting period <NUM>. Non-jetting pulse <NUM> leads jetting pulse <NUM> in the jetting period <NUM> of drive waveform <NUM>. Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a pulse on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes an active time window <NUM> that corresponds with the non-jetting pulse <NUM> and the jetting pulse <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM>. Other gating signals, such as MN3, may be ignored in this embodiment. When the active gating signal <NUM> (MN1) for the first print fluid <NUM> is selected, the driver output signal <NUM> will include non-jetting pulse <NUM> and jetting pulse <NUM>. When the active gating signal <NUM> (MN2) for the second print fluid <NUM> is selected, and the driver output signal <NUM> will include jetting pulse <NUM> but will not include non-jetting pulse <NUM>. Because the non-jetting pulse <NUM> has an opposite voltage direction than the jetting pulse <NUM> and is out-of-phase, the jetting energy at a jetting channel <NUM> for the first print fluid <NUM> will be lower than the jetting energy at a jetting channel <NUM> for the second print fluid <NUM>.

<FIG> illustrates the response of a jetting channel <NUM> to a non-jetting pulse <NUM> and a jetting pulse <NUM> in an illustrative embodiment. Line <NUM> represents volume displacement of a print fluid at a nozzle <NUM> of the jetting channel <NUM> in response to the non-jetting pulse <NUM> and the jetting pulse <NUM>. In this embodiment, non-jetting pulse <NUM> and jetting pulse <NUM> are in opposite voltage directions <NUM>-<NUM>. Non-jetting pulse <NUM> has in-phase timing with the resonant frequency of the jetting channel <NUM>. <FIG> illustrates the non-jetting cycle <NUM> of pressure waves within the jetting channel <NUM> in response to non-jetting pulse <NUM>. As is evident, pressure waves created by non-jetting pulse <NUM> are in-phase with pressure waves created by jetting pulse <NUM>. A non-jetting pulse <NUM> that is in the opposite voltage direction and in-phase increases the jetting energy at the jetting channel <NUM>, and increases droplet mass and velocity. Thus, the volume displacement peak <NUM> is higher than when a jetting pulse <NUM> is applied alone.

<FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of pulses for a jetting period <NUM>. Non-jetting pulse <NUM> leads jetting pulse <NUM> in the jetting period <NUM> of drive waveform <NUM>. Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a pulse on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes an active time window <NUM> that corresponds with the non-jetting pulse <NUM> and the jetting pulse <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM>. Other gating signals, such as MN3, may be ignored in this embodiment. When the active gating signal <NUM> (MN1) for the first print fluid <NUM> is selected, the driver output signal <NUM> will include non-jetting pulse <NUM> and jetting pulse <NUM>. When the active gating signal <NUM> (MN2) for the second print fluid <NUM> is selected, and the driver output signal <NUM> will include jetting pulse <NUM> but will not include non-jetting pulse <NUM>. Because the non-jetting pulse <NUM> has an opposite voltage direction than the jetting pulse <NUM> and is in-phase, the jetting energy at a jetting channel <NUM> for the first print fluid <NUM> will be higher than the jetting energy at a jetting channel <NUM> for the second print fluid <NUM>.

<FIG> illustrates the response of a jetting channel <NUM> to a non-jetting pulse <NUM> and a jetting pulse <NUM> in an illustrative embodiment. Line <NUM> represents volume displacement of a print fluid at a nozzle <NUM> of the jetting channel in response to the non-jetting pulse <NUM> and the jetting pulse <NUM>. In this embodiment, non-jetting pulse <NUM> and jetting pulse <NUM> are in the same voltage direction <NUM>. Non-jetting pulse <NUM> has out-of-phase timing with the resonant frequency of the jetting channel <NUM>. <FIG> illustrates the non-jetting cycle <NUM> of pressure waves within the jetting channel <NUM> in response to non-jetting pulse <NUM>. As is evident, pressure waves created by non-jetting pulse <NUM> are out-of-phase with pressure waves created by jetting pulse <NUM>, such as by <NUM> degrees. A non-jetting pulse <NUM> in the same voltage direction and out-of-phase decreases the jetting energy at the jetting channel <NUM>, and decreases droplet mass and velocity. Thus, the volume displacement peak <NUM> is lower than when a jetting pulse <NUM> is applied alone.

<FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of pulses for a jetting period <NUM>. Non-jetting pulse <NUM> leads jetting pulse <NUM> in the jetting period <NUM> of drive waveform <NUM>. Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a pulse on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes an active time window <NUM> that corresponds with the non-jetting pulse <NUM> and the jetting pulse <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes an active time window <NUM> that corresponds with the jetting pulse <NUM>. Other gating signals, such as MN3, may be ignored in this embodiment. When the active gating signal <NUM> (MN1) for the first print fluid <NUM> is selected, the driver output signal <NUM> will include non-jetting pulse <NUM> and jetting pulse <NUM>. When the active gating signal <NUM> (MN2) for the second print fluid <NUM> is selected, and the driver output signal <NUM> will include jetting pulse <NUM> but will not include non-jetting pulse <NUM>. Because the non-jetting pulse <NUM> has the same voltage direction as the jetting pulse <NUM> and is out-of-phase, the jetting energy at a jetting channel <NUM> for the first print fluid <NUM> will be less than the jetting energy at a jetting channel <NUM> for the second print fluid <NUM>.

Further, when a three-bit driver is implemented, driver circuit <NUM> may drive jetting channels <NUM> for four different print fluids <NUM>-<NUM> in two rows <NUM>-<NUM> of nozzles as shown in <FIG>, in a single row of nozzles, or more rows of nozzles. <FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes a series or train of non-jetting pulses <NUM> and jetting pulses <NUM> for a jetting period <NUM>. In this embodiment, drive waveform <NUM> includes three non-jetting pulses <NUM> followed by a jetting pulse <NUM>. It is assumed for this embodiment that each of the non-jetting pulses <NUM> are in-phase. Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a pulse on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes active time windows <NUM> that correspond with the jetting pulse <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes active time windows <NUM> that correspond with one non-jetting pulse <NUM> and the jetting pulse <NUM>. Gating signal <NUM> (MN3) is an active gating signal designated for jetting the third print fluid <NUM>, and includes active time windows <NUM> that correspond with two non-jetting pulses <NUM> and the jetting pulse <NUM>. Gating signal <NUM> (MN4) is an active gating signal designated for jetting the fourth print fluid <NUM>, and includes active time windows <NUM> that correspond with three non-jetting pulses <NUM> and the jetting pulse <NUM>. Other gating signals, such as MNS-MN7, may be ignored in this embodiment.

When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the active gating signal <NUM> designated for jetting the first print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks the other pulses. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the second print fluid <NUM>, driver circuit <NUM> outputs one non-jetting pulse <NUM> and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks other pulses. The jetting energy at the jetting channel <NUM> will be increased compared to driver output signal <NUM> due to non-jetting pulse <NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the third print fluid <NUM>, driver circuit <NUM> outputs two non-jetting pulses <NUM> and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks other pulses. The jetting energy at the jetting channel <NUM> will be increased compared to driver output signal <NUM> due to the two non-jetting pulses <NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the fourth print fluid <NUM>, driver circuit <NUM> outputs three non-jetting pulses <NUM> and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>. The jetting energy at the jetting channel <NUM> will be increased compared to driver output signal <NUM> due to the three non-jetting pulses <NUM>.

<FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes train of nonjetting pulses <NUM> and jetting pulses <NUM> for a jetting period <NUM>. In this embodiment, drive waveform <NUM> includes a series of three non-jetting pulses <NUM> followed by a jetting pulse <NUM>. It is assumed for this embodiment that each of the non-jetting pulses <NUM> are in-phase. Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a pulse on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes active time windows <NUM> that correspond with the jetting pulse <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes active time windows <NUM> that correspond with the first non-jetting pulse <NUM> in the series and the jetting pulse <NUM>. Gating signal <NUM> (MN3) is an active gating signal designated for jetting the third print fluid <NUM>, and includes active time windows <NUM> that correspond with the second non-jetting pulse <NUM> in the series and the jetting pulse <NUM>. Gating signal <NUM> (MN4) is an active gating signal designated for jetting the fourth print fluid <NUM>, and includes active time windows <NUM> that correspond with the third non-jetting pulse <NUM> in the series (i.e., the non-jetting pulse <NUM> preceding the jetting pulse <NUM>) and the jetting pulse <NUM>. Other gating signals, such as MN5-MN7, may be ignored in this embodiment.

When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the active gating signal <NUM> designated for jetting the first print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks the other pulses. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the second print fluid <NUM>, driver circuit <NUM> outputs the first non-jetting pulse <NUM> in the series and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks other pulses. The jetting energy at the jetting channel <NUM> will be increased compared to driver output signal <NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the third print fluid <NUM>, driver circuit <NUM> outputs the second non-jetting pulse <NUM> in the series and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks other pulses. The energy caused by a non-jetting pulse <NUM> will dissipate over time. Thus, the closer the non-jetting pulse <NUM> to the jetting pulse <NUM>, the more the energy will be increased. The jetting energy therefore is increased in driver output signal <NUM> compared to driver output signal <NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the fourth print fluid <NUM>, driver circuit <NUM> outputs the third non-jetting pulse <NUM> in the series and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>. The jetting energy at the jetting channel <NUM> will be increased compared to driver output signal <NUM>.

<FIG> is a signal diagram <NUM> for driver circuit <NUM> jetting multiple print fluids in an illustrative embodiment. Signal diagram <NUM> shows drive waveform <NUM> (i.e., Vcom) that includes train of nonjetting pulses <NUM> and jetting pulses <NUM> for a jetting period <NUM>. In this embodiment, drive waveform <NUM> includes a series of two non-jetting pulses <NUM> followed by a jetting pulse <NUM>. It is assumed for this embodiment that each of the non-jetting pulses <NUM> are in-phase. Signal diagram <NUM> also shows gating signals <NUM>-<NUM>. Gating signal <NUM> (MN0) is an inactive gating signal that does not allow a pulse on drive waveform <NUM> to pass to an actuator <NUM> of a jetting channel <NUM>. Gating signal <NUM> (MN1) is an active gating signal designated for jetting the first print fluid <NUM>, and includes active time windows <NUM> that correspond with the jetting pulse <NUM>. Gating signal <NUM> (MN2) is an active gating signal designated for jetting the second print fluid <NUM>, and includes active time windows <NUM> that correspond with the first non-jetting pulse <NUM> in the series and the jetting pulse <NUM>. Gating signal <NUM> (MN3) is an active gating signal designated for jetting the third print fluid <NUM>, and includes active time windows <NUM> that correspond with the second non-jetting pulse <NUM> in the series and the jetting pulse <NUM>. Gating signal <NUM> (MN4) is an active gating signal designated for jetting the fourth print fluid <NUM>, and includes active time windows <NUM> that correspond with both non-jetting pulses <NUM> and the jetting pulse <NUM>. Other gating signals, such as MN5-MN7, may be ignored in this embodiment.

When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises the active gating signal <NUM> designated for jetting the first print fluid <NUM>, driver circuit <NUM> outputs jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks the other pulses. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the second print fluid <NUM>, driver circuit <NUM> outputs the first non-jetting pulse <NUM> in the series and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks other pulses. The jetting energy at the jetting channel <NUM> will be increased compared to driver output signal <NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the third print fluid <NUM>, driver circuit <NUM> outputs the second non-jetting pulse <NUM> in the series and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>, and blocks other pulses. The jetting energy is increased in driver output signal <NUM> compared to driver output signal <NUM>. When the selected gating signal <NUM>-<NUM> for a jetting channel <NUM> comprises an active gating signal <NUM> for the fourth print fluid <NUM>, driver circuit <NUM> outputs both non-jetting pulses <NUM> and the jetting pulse <NUM> from drive waveform <NUM> as the driver output signal <NUM> (VDO) to the actuator <NUM> of the jetting channel <NUM>. The jetting energy at the jetting channel <NUM> will be increased compared to driver output signal <NUM>.

When driving jetting channels <NUM> for eight or more different print fluids, additional driver circuits <NUM> may be implemented that each drive four of the different print fluids.

Embodiments disclosed herein can take the form of software, hardware, firmware, or various combinations thereof. In one particular embodiment, software is used to direct a processing system of jetting apparatus <NUM> to perform the various operations disclosed herein. <FIG> illustrates a processing system <NUM> operable to execute a computer readable medium embodying programmed instructions to perform desired functions in an illustrative embodiment. Processing system <NUM> is operable to perform the above operations by executing programmed instructions tangibly embodied on computer readable storage medium <NUM>. In this regard, embodiments of the invention can take the form of a computer program accessible via computer-readable medium <NUM> providing program code for use by a computer or any other instruction execution system. For the purposes of this description, computer readable storage medium <NUM> can be anything that can contain or store the program for use by the computer.

Computer readable storage medium <NUM> can be an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor device. Examples of computer readable storage medium <NUM> include a solid-state memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and an optical disk. Current examples of optical disks include compact disk - read only memory (CD-ROM), compact disk - read/write (CD-R/W), and DVD.

Processing system <NUM>, being suitable for storing and/or executing the program code, includes at least one processor <NUM> coupled to program and data memory <NUM> through a system bus <NUM>. Program and data memory <NUM> can include local memory employed during actual execution of the program code, bulk storage, and cache memories that provide temporary storage of at least some program code and/or data in order to reduce the number of times the code and/or data are retrieved from bulk storage during execution.

Claim 1:
A driver circuit (<NUM>) communicatively couplable to actuators (<NUM>) of jetting channels of a printhead (<NUM>), the jetting channels comprising first jetting channels configured to jet a first print fluid (<NUM>), and second jetting channels configured to jet a second print fluid (<NUM>);
wherein the driver circuit is configured to receive a drive waveform (<NUM>) comprising non-jetting pulses (<NUM>) and jetting pulses (<NUM>, <NUM>, <NUM>);
wherein the driver circuit is configured to receive gating signals (<NUM>-<NUM>) comprising a first active gating signal designated for jetting the first print fluid, and a second active gating signal designated for jetting the second print fluid;
wherein the driver circuit is configured to selectively apply the non-jetting pulses and the jetting pulses from the drive waveform to the actuators of the first jetting channels based on the first active gating signal to jet the first print fluid;
wherein the driver circuit is configured to selectively apply the jetting pulses from the drive waveform to the actuators of the second jetting channels based on the second active gating signal to jet the second print fluid,
characterised in that
a jetting period (<NUM>) of the drive waveform includes a non-jetting pulse and a jetting pulse; and
for the jetting period, the driver circuit is configured to:
obtain print data (<NUM>) for the first jetting channels and the second jetting channels;
select a gating signal from the gating signals for each of the first jetting channels and the second jetting channels based on the print data;
when the gating signal selected for a first jetting channel of the first jetting channels comprises the first active gating signal, output the non-jetting pulse and the jetting pulse from the drive waveform as a first driver output signal to the actuator of the first jetting channel;
when the gating signal selected for a second jetting channel of the second jetting channels comprises the second active gating signal, output the jetting pulse from the drive waveform as a second driver output signal to the actuator of the second jetting channel, wherein the non-jetting pulse is blocked from the second driver output signal based on the second active gating signal.