Method, apparatus, and circuit for trimming droplet ejection signals

Abstract

Circuits, systems, and methods for reducing heat generation in a print head are disclosed. An input unit is provided for receiving at least two common drive waveforms and a trimming signal. An output unit is also provided for supplying individual drive waveforms to actuators. A waveform selection unit is configured to couple the common drive waveform to an output unit for connecting to a first electrode of an actuator, and the waveform selection unit is configured to supply an individual drive waveform to one of the selected actuators based on a first common drive waveform, a second common drive waveform, and a trimming signal, causing a transition from the first common drive waveform to the second common drive waveform at a timing determined by the trimming signal.

Description

[Technical Field]

[0001] This application relates to a droplet dispensing device and a method for controlling the dispensing of fluid droplets in a consistent manner. In particular, the systems and methods described herein aim to efficiently achieve these objectives while suppressing heat generation in the droplet dispensing device. [Background technology]

[0002] Droplet dispensers equipped with at least one droplet dispensing head are currently widely used in conventional applications such as inkjet printing, as well as in material deposition applications such as 3D printing and other rapid prototyping technologies, and surface printing of raised patterns such as Braille and decorative raised patterns. In such material deposition applications, it is sometimes desirable to deposit a relatively large amount of fluid onto a medium using a droplet dispensing head. In some cases, the fluid may acquire new chemical properties and enhance the functionality of the deposited material upon adhesion to the new medium.

[0003] Recently, a droplet dispensing head has been developed that allows ink and varnish to be applied directly to ceramic tiles, achieving high reliability and processing capacity. This not only allows for the customization of tile patterns to meet customer specifications, but also reduces the need to stock all types of tiles.

[0004] In other applications, droplet dispensing heads may be used to form elements such as color filters for LCD or OLED displays, for example, in the manufacture of flat-screen televisions.

[0005] Thus, it is understandable that droplet ejection heads continue to evolve and specialize to suit new or increasingly challenging thin-film deposition applications. However, despite much development in the field of droplet ejection heads, there is still room for improvement.

[0006] In particular, droplet dispensing heads typically consist of an array of fluid chambers having electrically drivable walls, each of which is driven to selectively dispense droplets. Typically, this droplet dispensing is achieved by forming at least one actuator wall of the fluid chamber from a piezoelectric material and using electrodes to move the actuator wall of the fluid chamber, thereby changing its volume.

[0007] However, the response of each fluid chamber to the control signal is not necessarily the same. The performance of each piezoelectric actuator may be affected by one or more of the following factors: —Manufacturing tolerances for fluid chambers, e.g., variations in the shape or size of fluid chambers; —Various types of crosstalk from nearby actuators (electrical, fluid, mechanical, etc.); —Printing frequency; — Ambient temperature and fluid temperature. These can alter various properties of the fluid, such as viscosity, potentially affecting the volume and velocity of the ejected droplets; —The time elapsed since the actuator last ejected a droplet. This can lead to non-uniform droplet characteristics due to fluctuations in the stored energy within each fluid chamber; —The period during which the fluid chamber was used. For example, fluid chambers can degrade with repeated use;

[0008] These variations affect droplet velocity / volume and shape, causing image quality errors and artifacts during printing. Variations between two actuators can be mitigated by adjusting the droplet velocity or volume for each actuator and implementing a trimming mechanism that allows the printing system to control the actuators individually. When properly implemented, this enables uniform droplet ejection.

[0009] There are two basic methods for supplying drive signals to the droplet dispensing head: the hot switch method and the cold switch method.

[0010] The hot-switching method is so named because the drive waveform is generated within the droplet ejection head, and the power consumption of the integrated circuit that generates the drive waveform heats the droplet ejection head, with power consumption increasing as the printing speed increases. In the hot-switching method, the waveform is generated within the droplet ejection head and can be easily adjusted to suit each actuator, making it easy to generate individual drive waveforms for each actuator. However, cooling the integrated circuit and keeping it at or near its operating temperature is far more difficult. Furthermore, reducing heat dissipation within the head is advantageous.

[0011] In the cold-switched method, a common drive waveform (CDW) is generated outside the droplet ejection head, and the electronics within the head simply connect the CDW to the appropriate actuator. This method makes it easier to cool the electronics within the droplet ejection head and maintain them at or near operating temperature, as most of the power consumed during waveform generation is consumed by the drive circuitry outside the droplet ejection head. However, the cold-switched method has limitations in providing individual drive waveforms, as only one common drive waveform is available, and this waveform is presented to all actuators during printing and not when not printing. In this context, it is not possible to tailor individual drive waveforms to individual actuators.

[0012] One way to provide a trimming mechanism is to vary the amplitude of a common drive waveform according to the required trimming, since the velocity and volume of the droplets are functions of the waveform amplitude, and then apply the adjusted waveform to each individual actuator. However, since there is only one common drive waveform and its amplitude is already fixed, it is impossible to perform "voltage trimming" in a simple cold-switch environment. Other trimming solutions also exist that allow for some modification of the waveform appearing at each nozzle. Typically, they use one or more variations of the CDW and allow the waveform appearing at each nozzle to be changed by switching the CDW and one or more variations at different points in the waveform. However, this can lead to increased power consumption of the integrated circuit and the loss of some of the thermal advantages of cold switching.

[0013] This invention is intended to solve some or all of the problems identified above. [Overview of the project]

[0014] Aspects of the present invention are described in the appended independent claims, and specific embodiments of the present invention are described in the appended dependent claims.

[0015] Therefore, this specification discloses a circuit for controlling a plurality of actuators respectively associated with at least one fluid chamber in a droplet ejection device. This circuit includes an input section for receiving a first common drive waveform, a second common drive waveform, and a trimming signal, an output section for supplying an individual drive waveform to the actuator, and a waveform selection section configured to couple to the output section for connecting to the first electrode of the first common drive waveform and the actuator, and based on the first common drive waveform, the second common drive waveform, and the trimming signal, configured to supply an individual drive waveform to a selected one of the actuators. The waveform selection section is further configured to cause a transition from the first common drive waveform to the second common drive waveform by disconnecting the first common drive waveform from the output section and coupling the second common drive waveform to the output section, and this transition occurs at a timing determined by the trimming signal.

[0016] By explicitly using two different common drive waveforms in a form with a transition between them, various trimming effects can be realized. This includes those with shapes as shown in the figure. There are several general shapes that can be used in this context. The first shape reaches a peak at an initial high value (large amplitude, that is, a positive or negative value), and then after a certain time (controlled by the trimming signal), it decreases to a low value (smaller amplitude, still positive if the large amplitude is positive, negative if the large amplitude is negative), forming a flat part or a shoulder in the plot of voltage against time. Other general shapes include those that increase to an initial low amplitude, maintain that value for a certain time, and then increase to a large amplitude over a further certain time. In any case of adopting these shapes, with this approach, the heat generation location can be moved away from the droplet ejection head. In particular, by moving the complexity of generating the two common drive waveforms outside the head, the heat generated in the head can be minimized as much as possible. The only chamber-specific transition occurring on the head is the switching between the two common drive waveforms at the time point determined by the trimming signal.

[0017] The common drive waveform here refers to the waveform supplied to or available for a plurality of (in some cases all) actuators. Since each actuator generates an output based on the same common drive waveform, the supply of input signals to the droplet ejection head is simple and synchronized among all actuators (each actuator receives the same basic signal, and a drive waveform dedicated to each actuator is configured therefrom).

[0018] Optionally, the waveform selection unit is further configured to receive different trimming signals supplied to the input unit, thereby generating transitions between common drive waveforms at different times, and supplying different individual drive waveforms to different output units of different actuators within the droplet ejection device. This provides an easy way for different actuators to receive different signals according to compensation requirements (for example, considering differences in shape between different chambers and other non-uniformities described in more detail below). In other words, by supplying a dedicated trimming signal to the circuit, transitions between two common drive waveforms may occur at times specific to each actuator.

[0019] Optionally, the waveform selection unit is configured to receive a dedicated trimming signal for each actuator associated with each output, causing transitions between common drive waveforms at timings specific to each actuator. Here, "dedicated" does not necessarily mean that all trimming signals cause transitions at different timings; rather, compensation requirements allow for the selection of timing for each actuator based on the characteristics of each actuator / fluid chamber, mitigating variations in droplet discharge characteristics due to differences in actuator / fluid chamber characteristics. Therefore, generally, all trimming signals may be different, and may be different in specific examples, but in some cases, different fluid chambers may have manufacturing parameters that lead to the same droplet discharge characteristics, resulting in those fluid chambers receiving the same trimming signal and / or being supplied with the same trimmed drive waveform. Furthermore, note that for fluid chambers / actuators that do not require compensation, the trimming signal may be zero. Note that in this document, the terms "individual drive waveform" and "trimmed drive waveform" are used interchangeably.

[0020] Optionally, the trimming signals for actuators or each actuator can be derived empirically. For example, specific characteristics of the fluid chambers and / or actuators can be measured to determine trimming signals that best relax those characteristics and bring each fluid chamber closer to the same discharge characteristics. In some cases, the discharge characteristics may be adjusted in this way to match the discharge characteristics of a particular fluid chamber, or the discharge characteristics of each fluid chamber may be adjusted to match a desired or predetermined set of discharge characteristics. Fluid chamber characteristics include, for example, the thickness of the actuator, the material forming the actuator, the volume of the fluid chamber, the dimensions of the fluid chamber, and the position of the actuator (e.g., roof mode or shared wall). This type of empirical derivation may include, for example, printing with a specific trimming value, checking the output (manually or with machine assistance), adjusting the trimming value, and repeating this process with new trimming values ​​until the printed output is desired. Trimming signals can also be used in high-speed printing to mitigate fluid turbulence caused by the movement of a particular fluid chamber or adjacent fluid chambers.

[0021] Optionally, the trimming signal is updated iteratively. This includes, for example, periodically evaluating whether the trimming values ​​are still optimal for one or more fluid chambers. As a non-limiting example, the evaluation can be carried out according to the following methods: —Fixed schedule (e.g., daily, weekly, monthly); if a specific printing error (by human or machine) is detected, diagnostic procedures, including readjustment of trimming, may be performed; —Each time the device is powered off and restarted, or each time it becomes inactive for a specified period of time; —When a temperature change is detected (for example, a temperature change that exceeds a threshold temperature for at least a certain period of time); —Detection that the device has moved to a new location; —Types of fluids discharged from the fluid chamber (those with different properties such as viscosity); —Types of print media; —Changing the print mode (changing the number of droplets ejected per dot - 1 droplet per dot (dpd) printing and multi-dpd printing) — Continuously monitor print quality, temperature, and other relevant parameters such as complete or partial nozzle clogging, and adjust the trimming signal on the fly.

[0022] In some cases, the trimming values ​​are set to factory default values ​​(or calibrated at the factory), and a calibration routine may be performed as part of the initial setup or periodic setup after the droplet dispensing head is installed in the droplet dispensing device, or when the droplet dispensing device detects a change in the dispensing system. For example, the droplet dispensing device may detect a change in one or more of the parameters of the evaluation described above.

[0023] The common drive waveform may consist of multiple pixel periods. Optionally, the common drive waveform may be periodic, consisting of cycles of pixel periods, and these cycles may repeat over the duration of the common drive waveform. This repeating nature means that the same trimmed drive waveform can be used for its actuator, and to generate transitions simultaneously in each cycle, it is only necessary to synchronize with the repeating period of the common drive waveform. Similarly, the relative timing differences between different trimmed signals for supplying dedicated control signals to two or more (or each) actuators can be maintained simply by repeating over the same common drive waveform period, as the system remains synchronized.

[0024] Optionally, during the first period of the printing cycle, the first common drive waveform is maintained at the first voltage V1 and the second common drive waveform is maintained at the second voltage V2; and thereafter, during the second period of the printing cycle, the first common drive waveform is maintained at the third voltage V3 and the second common drive waveform is held at the fourth voltage V4. 。Here, V3 is lower than V1, and V4 is lower than V2. Here, "lower" means "closer to the nominal baseline reference voltage" when both voltages are positive (sometimes referred to as V0 in this specification, with respect to a certain nominal baseline reference voltage), "negative" when the two voltages are on both sides of V0, and "more negative" when both voltages are negative. Usually, the voltages are arranged in descending order of numerical value, that is, V4 is lower than V3, V3 is lower than V2, and V1 is the highest (i.e., V4 < V3 < V2 < V1). Optionally, the first and second common drive waveforms include a discharge waveform component and a non-discharge waveform component, and the waveform selection unit causes a transition between the discharge waveform component of the first common drive waveform and the non-discharge waveform component of the second common drive waveform in response to the trimming signal, and / or the waveform selection unit causes a transition between the discharge waveform component of the second common drive waveform and the non-discharge waveform component of the first common drive waveform in response to the trimming signal. For example, the non-discharge waveform component causes deformation of the actuator, but the deformation is insufficient to cause discharge. On the other hand, the discharge waveform component not only causes deformation of the actuator but also has a waveform component sufficient to discharge droplets. The discharge waveform component is usually a component with a larger amplitude (i.e., farther from the nominal baseline V0) than the non-discharge waveform component. A trimmed output is generated by the transition between the discharge waveform component and the non-discharge waveform component. The amount of trimming is controlled by the timing of the transition.

[0025] Optionally, the first common drive waveform is a discharge waveform, the second common drive waveform is a non-discharge waveform, and the waveform selection unit causes a transition between the discharge waveform and the non-discharge waveform in response to the trimming signal. The maximum amplitudes of the first common drive waveform and the second common drive waveform may be different, and the amplitude of the first common drive waveform is larger than the amplitude of the second common drive waveform.

[0026] Optionally, a trimming signal causes a transition from a first common drive waveform to a second common drive waveform during the first period of the print cycle. Optionally, the trimming signal is the first trimming signal. Furthermore, a second trimming signal may exist that causes a transition from the second common drive waveform to the first common drive waveform during the second period of the print cycle. Further optional, a third trimming signal may exist that causes a transition from the first common drive waveform to the second common drive waveform during the third period of the print cycle. Furthermore, a fourth trimming signal may exist that causes a transition from the first common drive waveform to the second common drive waveform during the fourth period of the print cycle. Providing two or more trims in the waveform increases the flexibility in adjusting the drive waveform supplied to the actuator to compensate for specific variations in the discharge characteristics of a given fluid chamber. However, it should be noted that trimming can only be applied during the first period of the print cycle. Also, depending on the requirements, only one trimming signal may be applied per period.

[0027] Each common drive waveform can change periodically with a period T. In some cases, further flexibility can be achieved by providing a trimming signal that changes the output applied from the circuit to the actuator with each period T by varying the transition time between two or more common drive waveforms within each period T. In other words, the trimming signal can be updated or changed in each iteration.

[0028] Optionally, the circuit may include another further input section for receiving a third common drive waveform, and a waveform selector section may be configured to further couple the third common drive waveform to a second output section for connecting it to a second electrode of an actuator. This allows a predetermined signal to be applied to the second electrode. For example, the two electrodes may be placed on either side of a planar piezoelectric element. By supplying a known signal to the second electrode, a certain amount of deformation can be provided to the piezoelectric material as a standard. This provides a known background from which the first electrode can induce its own deformation. For example, the first electrode may either amplified or partially canceled out the deformation brought about by the third common drive waveform applied to the second electrode, thereby adding further nuance to the available trimming options.

[0029] In a further example, the circuit includes another further input for receiving a fourth common drive waveform, and a waveform selector is further coupled to a second output for connecting a third or fourth common drive waveform to a second electrode of the actuator, and configured to produce a transition between the third and fourth common drive waveforms in response to a third trimming signal. Such a configuration allows trimmed drive signals to be supplied to both the first and second electrodes, further increasing the flexibility of the available trimming options. In some cases, the third common drive waveform is an inverted form of the first common drive waveform, and / or the fourth common drive waveform is an inverted form of the second common drive waveform. This simplifies the system because each waveform can be associated with the others by a simple transformation (in this case, inversion). In such cases, the second common drive waveform can be provided by directly inverting the first common drive waveform, rather than explicitly providing a separate second waveform.

[0030] In any example described herein, if a waveform selector receives two or more inputs and / or outputs two or more outputs, this may be understood as a single waveform selector having three or more inputs and / or two or more outputs. Alternatively, it may be provided as multiple waveform selectors having collectively the total number of inputs and outputs necessary to provide the required configuration. In some cases, this may mean that not all coupling to the actuator is provided by the waveform selector. For example, in the above example where there are only three common drive waveforms, a waveform selector may be provided to handle the transition between the first and second common drive waveforms, but coupling between the third common drive waveform and the second electrode may not necessarily require a waveform selector and may instead be provided simply by connecting the third common drive waveform to the second electrode via a drive circuit.

[0031] The common drive waveform may start and / or end at a reference voltage level. This level is, for example, the value denoted as V0 above, and serves as a useful reference point for the signal.

[0032] If necessary, two or more common drive waveforms may each have a positive and a negative component relative to the reference voltage level. Here, the positive component of the first common drive waveform has a larger amplitude than the positive component of the second common drive waveform, and / or the positive component of the third common drive waveform has a larger amplitude than the positive component of the fourth common drive waveform, and / or the negative component of the first common drive waveform has a smaller amplitude than the negative component of the second common drive waveform, and / or the negative component of the third common drive waveform has a smaller amplitude than the negative component of the fourth common drive waveform. These waveform forms provide a convenient choice for transitioning from one common drive waveform to another and providing an adjusted output to supply to the actuator accordingly. Here, a low amplitude of the negative component means a small absolute value, which is consistent with discussions elsewhere in this specification.

[0033] The circuit described above may be provided in combination with a droplet dispensing head and a plurality of actuators, each actuator associated with at least one fluid chamber.

[0034] Furthermore, the Specified Specification discloses a droplet dispensing device comprising one or more droplet dispensing heads, each droplet dispensing head comprising a plurality of actuators, each actuator associated with at least one fluid chamber, and comprising a circuit for controlling the plurality of actuators, the circuit comprising an input unit for receiving a first common drive waveform, a second common drive waveform, and a trimming signal, an output unit for supplying individual drive waveforms to actuators, and a waveform selection unit configured to be coupled to the output unit for connecting the first common drive waveform and a first electrode of the actuator, wherein the waveform selection unit further comprises a waveform selection unit configured to supply an individual drive waveform to one of the actuators selected based on the first common drive waveform, the second common drive waveform, and the trimming signal, the waveform selection unit further comprises a waveform selection unit configured to cause a transition from the first common drive waveform to the second common drive waveform by disconnecting the first common drive waveform from the output unit and coupling the second common drive waveform to the output unit, the transition occurring at a timing determined by the trimming signal.

[0035] The droplet ejection device may further include an ejection signal input unit that receives information specifying whether each actuator is an ejection chamber or a non-ejection chamber for each printing cycle.

[0036] Optionally, the fluid chambers associated with the actuators may be arranged in three groups designated A, B, and C, and any set of three adjacent fluid chambers may be arranged such that each of the fluid chambers from groups A, B, and C contains at least one. Alternatively, the fluid chambers may be arranged so that the actuators belonging to each of the three groups are arranged in the same order to form a repeating pattern. Optionally, each period of length T in a print cycle may have three subcycles, designated as A subcycle, B subcycle, and C subcycle. Fluid chambers with designations that do not match the subcycle designations are designated as inactive fluid chambers, and fluid chambers with designations that match the subcycle designations are assigned as active fluid chambers. Furthermore, fluid chambers with designations that match the subcycle designations may be further assigned as active discharge fluid chambers or active non-discharge fluid chambers depending on the print signal. This enables multi-cycle discharge and reduces crosstalk by arranging the fluid chambers so that adjacent fluid chambers do not discharge simultaneously. While this specific example concerns three-cycle discharge, other examples may also allow discharge over two or any number of cycles beyond three, within the scope of the general principles presented herein.

[0037] Optionally, a common inactive waveform may be supplied to the actuator associated with the inactive fluid chamber, and a common active non-discharge waveform may be supplied to the actuator associated with the active non-discharge fluid chamber. Furthermore, the waveform selection unit may be configured to receive a dedicated trimming signal input to each active discharge fluid chamber, control the transition between the first common drive waveform and the second common drive waveform, and output a dedicated drive waveform to be supplied to the actuator associated with each active discharge fluid chamber. This ensures that appropriately trimmed operating signals are provided only to the fluid chambers intended to discharge at a predetermined time.

[0038] The waveform selection unit optionally includes a switching circuit configured to perform a transition from the first common drive waveform to the second common drive waveform.

[0039] The waveform selection unit optionally includes at least two switching circuits that are controlled by switch control and configured to transition from the first common drive waveform to the second common drive waveform.

[0040] Optionally, the dispensing device further comprises a timing circuit configured to control the transition from the first common drive waveform to the second common drive waveform, the transition occurring at a timing determined by the trimming signal.

[0041] The above or each of the switches further comprises a high-resistance path and a low-resistance path, the high-resistance path being configured to enable the transition from the first common drive waveform to the second common drive waveform.

[0042] In another example, the fluid chambers may be designated alternately as active and inactive fluid chambers. The waveform selector may be configured to receive a dedicated trimming signal input for each active discharge fluid chamber, control the transition between the first and second common drive waveforms, and output a dedicated drive waveform supplied to the actuator associated with each active discharge fluid chamber. In other words, in this example, each active fluid chamber is directly adjacent to (or sandwiched between) two inactive fluid chambers, and each inactive fluid chamber is directly adjacent to (or sandwiched between) two active fluid chambers (except that the fluid chambers at both ends of the row are adjacent to only one of the other type of fluid chamber). This is another way to ensure that a fluid chamber intended to discharge droplets is not directly adjacent to another fluid chamber intended to discharge droplets, thereby reducing crosstalk.

[0043] Optionally, the waveform selection unit can be configured to generate one or more further transitions between the first common drive waveform and the second common drive waveform. These transitions can occur in either direction, i.e., a transition from the first common drive waveform to the second common drive waveform, or a transition from the second common drive waveform to the first common drive waveform, as applicable and as needed, thereby increasing the flexibility of the trimming implementation method.

[0044] Optionally, the timing circuit can be configured to output a trimming signal during the attraction, emission, or enhancement phase of the common drive waveform. As mentioned above, these phases are as follows: Suction phase: A phase in which the volume of the fluid chamber increases and additional fluid is drawn in. Discharge Phase: The phase in which the volume of the fluid chamber decreases from the volume at the end of the suction phase. This initiates the droplet discharge process (also commonly referred to herein as droplet ejection). Enhancement Phase: A phase in which the volume of the fluid chamber continues to decrease after the end of the release phase, enhancing the release of droplets.

[0045] Following the reinforcement phase, a cancellation phase is typically applied. This is the final volume change to return the fluid chamber volume to the volume at the start of the suction phase, thus repeating the process through these four phases. In other words, a printing cycle for one fluid chamber consists of the suction phase, release phase, reinforcement phase, and cancellation phase in that order. The cancellation phase may be trimmed in some cases.

[0046] In some cases, the common drive waveform has only an suction phase and a discharge phase, in which case the discharge phase can be stopped when the volume of the fluid chamber returns to the volume at the start of the suction phase.

[0047] As described above, the volume of the fluid chamber is modified by supplying drive waveforms to the actuator. These drive waveforms are trimmed (i.e., transitions between common drive waveforms) in at least one of the phases described above to ensure that each fluid chamber ejects droplets in a desired manner. For example, each fluid chamber is made to have substantially uniform droplet ejection characteristics.

[0048] Optionally, the droplet dispensing device further comprises a further input for receiving a third common drive waveform, wherein the waveform selection unit is further configured to couple the third common drive waveform to a second electrode of an actuator. Optionally, the droplet dispensing device further comprises another further input for receiving a fourth common drive waveform, wherein the waveform selection unit is further configured to couple the third or fourth common drive waveform to the second electrode of the actuator in response to the third trimming signal. As described above, this improves flexibility in adjusting the drive waveform to suit the characteristics of a given fluid chamber or a given actuator.

[0049] As is generally described herein, when two drive signals are supplied to different electrodes associated with a single actuator, various possibilities exist. In order of increasing complexity, the options are as follows: 1. The same trimming signal can be used to generate the output supplied to each electrode. In other words, transitions between common drive waveforms occur simultaneously at both electrodes. 2. Using two separate trimming signals, it is possible to generate different independent outputs for each electrode, leading to transitions between common drive waveforms that may occur at different timings for the two electrodes. 3. A single trimmed signal with timing encoded to match the different transition times on each electrode. 4. A single trimmed signal with sufficient information transmission capability to encode multiple transitions at different times on each electrode.

[0050] Optionally, the third common drive waveform is an inverted version of the first common drive waveform, and / or the fourth common drive waveform is an inverted version of the second common drive waveform.

[0051] Optionally, each common drive waveform has a positive and a negative component relative to the reference voltage, where the positive component of the first common drive waveform has a higher amplitude than the positive component of the second common drive waveform, and / or the positive component of the third common drive waveform has a higher amplitude than the positive component of the fourth common drive waveform, and / or the negative component of the first common drive waveform has a lower amplitude than the negative component of the second common drive waveform, and / or the negative component of the third common drive waveform has a lower amplitude than the negative component of the fourth common drive waveform. These waveform forms provide a convenient set of choices for transitions between waveforms to provide a trimmed output for supplying to the actuator. Here, a low amplitude for the negative component means a small absolute value, which is consistent with discussions elsewhere in this specification.

[0052] The droplet ejector may further include a signal generator connected to the input and supplying a common drive waveform. This provides a complete system capable of generating and supplying a common drive waveform and a trimmed drive signal to the actuator. Optionally, the signal generator is located outside the head, and the waveform selector is located on the head. This allows the circuit to be located as far away from the droplet ejection head as possible, minimizing heat generation at the droplet ejection head. Here, "outside the head" means away from the droplet ejection head, and "on the head" means located on or adjacent to the droplet ejection head. In some cases, components on the head may be integrally formed with the droplet ejection head.

[0053] Furthermore, this specification also discloses methods corresponding to the circuits and apparatus described above, which also offer similar advantages. These methods include controlling a plurality of actuators, each associated with at least one fluid chamber in a droplet ejector. This method includes receiving first and second common drive waveforms, receiving a trimming signal, coupling the first common drive waveform to a first electrode of a first actuator during a printing cycle, disconnecting the first common drive waveform from the first electrode of the first actuator and coupling the second common drive waveform to the first electrode of the first actuator in response to the trimming signal, the transition occurring at a timing determined by the trimming signal.

[0054] Selectively, receiving a trimming signal may include receiving multiple different trimming signals, each of which is used to generate different output drive waveforms for different actuators as needed, and transitions between common drive waveforms may occur at different timings.

[0055] A dedicated trimming signal is received for each actuator, a dedicated drive waveform is supplied to each actuator, and a transition between the common drive waveforms occurs for each actuator at a timing specific to that actuator.

[0056] Optionally, the method further includes empirically determining the optimal trimming signal for the actuator or each actuator. Optionally, the method further includes iteratively updating the trimming signal.

[0057] Optionally, the common drive waveform is periodic and repeats for each period of the print cycle. In other words, this method can be repeated to eject additional droplet sets. The time between equivalent parts of this method is T, and the repeating period of the waveform is also T.

[0058] Optionally, during the first period of the print cycle, the first common drive waveform is maintained at the first voltage V1. 、 The second common drive waveform is maintained at the second voltage V2. 、 Next, during the second period of the printing cycle, the first common drive waveform is maintained at the third voltage V3. 、 The second common drive waveform is maintained at the fourth voltage V4. 、 Here, V3 is lower than V1, and V4 is lower than V2.

[0059] Optionally, the first and second common drive waveforms include an output waveform component and a non-output waveform component, and the individual drive waveform is provided in response to a trimming signal by a transition between the output waveform component of the first common drive waveform and the non-output waveform component of the second common drive waveform, and / or the individual drive waveform is provided in response to a trimming signal by a transition between the output waveform component of the second common drive waveform and the non-output waveform component of the first common drive waveform.

[0060] Optionally, the first common drive waveform is a discharge waveform, and the second common drive waveform is a non-discharge waveform, and the actuator waveform is provided by a transition between the discharge waveform and the non-discharge waveform in response to a trimming signal.

[0061] Optionally, the trimming signal causes a transition from a first common drive waveform to a second common drive waveform during a first period of the print cycle. Optionally, the trimming signal is the first trimming signal. Furthermore, there may be a second trimming signal that causes a further transition from a second common drive waveform to the first common drive waveform during a second period of the print cycle. In addition, or alternatively, the trimming signal may cause a transition from a second common drive waveform to a first common drive waveform during a first period, in which case the trimming signal may be the first trimming signal. Furthermore, the second trimming signal may cause a further transition from a first common drive waveform to a second common drive waveform during a second period of the print cycle.

[0062] Selectively, each common drive waveform is periodic with period T.

[0063] Optionally, this method further includes receiving a third common drive waveform and coupling the third common drive waveform to a second electrode of an actuator.

[0064] Optionally, this method further includes receiving a fourth common drive waveform and a third trimming signal, and coupling a second drive waveform to a second electrode of an actuator. The second drive waveform is provided by a transition between a third common drive waveform and a fourth common drive waveform at a timing determined by the third trimming signal. Optionally, the third common drive waveform is an inverted form of the first common drive waveform, and / or the fourth common drive waveform is an inverted form of the second common drive waveform.

[0065] Optionally, the common drive waveform starts and / or ends at the reference voltage level. Optionally, each common drive waveform has a positive and a negative component relative to the reference voltage level, where the positive component of the first common drive waveform has a higher amplitude than the positive component of the second common drive waveform, and / or the positive component of the third common drive waveform has a higher amplitude than the positive component of the fourth common drive waveform, and / or the negative component of the first common drive waveform has a lower amplitude than the negative component of the second common drive waveform, and / or the negative component of the third common drive waveform has a lower amplitude than the negative component of the fourth common drive waveform.

[0066] Optionally, a drive waveform is supplied to multiple actuators, each actuator associated with at least one fluid chamber, and this method further includes receiving a drive waveform for each print cycle that designates each actuator as either an ejection fluid chamber or a non-ejection fluid chamber.

[0067] Optionally, the fluid chambers to which each actuator is associated are arranged into three groups, A, B, and C, such that any set of the three adjacent fluid chambers contains at least one of each of the fluid chambers from A, B, and C, and the fluid chambers are arranged such that the actuators belonging to each of the three groups are arranged in the same order and in a repeating pattern.

[0068] Optionally, each period of length T has three subcycles designated as A subcycle, B subcycle, and C subcycle. Fluid chambers with designations that do not match the subcycle designations are assigned as inactive fluid chambers, and only fluid chambers with designations that match the subcycle designations are assigned as active fluid chambers. Fluid chambers with designations that match the subcycle designations are further assigned as active discharge fluid chambers or active non-discharge fluid chambers according to the drive waveform.

[0069] Optionally, a common inactive waveform is supplied to the actuator associated with the inactive fluid chamber, and a common active inactive discharge waveform is supplied to the actuator associated with the active inactive discharge fluid chamber. A dedicated trimming signal is received for each active discharge fluid chamber to control the transition between the first and second common drive waveforms, thereby outputting a dedicated active discharge waveform for each active discharge fluid chamber.

[0070] Optionally, fluid chambers are permanently designated as either active or inactive fluid chambers, and a dedicated trimming signal is received for each active discharge fluid chamber to control the transition between the first and second common drive waveforms, thereby outputting a dedicated active discharge waveform for each active discharge fluid chamber.

[0071] Optionally, the method further includes one or more further transitions between the first and second common drive waveforms. Optionally, the timing at which the trimming signal triggers one or each transition between the common drive waveforms is during the attraction, emission, or enhancement phase of the common drive waveform.

[0072] Optionally, this method further includes receiving a third common drive waveform and coupling the third common drive waveform to a second electrode of the actuator.

[0073] Optionally, this method further includes receiving a fourth common drive waveform and a third trimming signal, and coupling the drive waveform to a second electrode, the drive waveform being provided by a transition between the third common drive waveform and the fourth common drive waveform at a timing determined by the third trimming signal.

[0074] Optionally, the third common drive waveform is an inverted version of the first common drive waveform, and / or the fourth common drive waveform is an inverted version of the second common drive waveform.

[0075] Optionally, each common drive waveform has a positive component and a negative component with respect to the reference voltage, the positive component of the first common drive waveform has a higher amplitude than the positive component of the second common drive waveform, and / or the positive component of the third common drive waveform has a higher amplitude than the positive component of the fourth common drive waveform, and / or the negative component of the first common drive waveform has a lower amplitude than the negative component of the second common drive waveform, and / or the negative component of the third common drive waveform has a lower amplitude than the negative component of the fourth common drive waveform.

[0076] Optionally, a signal generator supplying a common drive waveform is placed outside the head, while waveform coupling and separation operations are performed inside the head. [Brief explanation of the drawing]

[0077] Embodiments of the present invention will be described with reference to the drawings for illustrative purposes only. [Figure 1] Figure 1 shows the waveform selection connection to the actuator in the first example. [Figure 2] Figure 2 shows examples of four common drive waveforms used in the example shown in Figure 1, which provide a regulated output applied to electrodes controlling the walls of the fluid chamber. [Figure 3] Figure 3 shows the trimmed drive waveform applied to the first electrode 131b in the example shown in Figure 1. [Figure 4] Figure 4 shows the trimmed drive waveform applied to the second electrode 131a in the example shown in Figure 1. [Figure 5] Figure 5 shows a schematic diagram of a circuit for carrying out the method disclosed herein. [Figure 6] Figure 6 shows a block diagram of two drive circuits to an actuator related to a modified example of the first example. [Figure 6A] Figure 6A shows an example of the switching circuit arrangement in the waveform selection shown in Figure 6. [Figure 7] Figure 7 shows a schematic diagram of the electrical connections to electrodes on the actuator wall separating the fluid chambers in the second example. [Figure 8] Figure 8 shows the resulting voltage applied to the first actuator wall according to the second example. [Figure 9] Figure 9 shows a block diagram of the drive circuit for each fluid chamber and its connection to the corresponding actuator according to the third example. [Figure 9A] Figure 9A shows an example of the switching circuit arrangement in the waveform selection shown in Figure 9. [Figure 10] Figure 10 shows an example of a typical active-on drive waveform for use in the active-on fluid chamber of the third example. [Figure 11] Figure 11 shows an example of a common inactive drive waveform for use in an inactive fluid chamber in the third example. [Figure 12]Figure 12 shows an example of a typical active-off drive waveform suitable for application to the active-off fluid chamber of the third example. [Figure 13] Figure 13 shows the circuit diagrams and equivalent circuit diagrams of a composite pass gate with high internal resistance and a composite pass gate with low internal resistance. [Figure 14] Figure 14 shows the circuit diagrams and equivalent circuit diagrams of a composite pass gate with high internal resistance and a composite pass gate with low internal resistance. [Figure 15] Figure 15 shows an example of a tuned active-on drive waveform supplied to the electrodes of an active-on actuator by the temporal transition between the waveforms in Figure 10. [Figure 16] Figure 16 shows examples of trimmed active ON drive waveforms formed using various trimming options based on the waveform in Figure 9. [Figure 17] Figure 17 shows the alternating arrangement of active and inactive fluid chambers and the associated electrode connections for use in the fourth example. [Figure 18] Figure 18 shows an example of a typical active-on drive waveform used in an active-on fluid chamber in the fourth example. [Figure 19] Figure 19 shows an example of a trimmed active-on drive waveform applied to an active-on actuator and formed using different trimming options based on the waveform in Figure 18. [Figure 20] Figure 20 shows an example of a common drive waveform used when supplying a trimmed signal to the active fluid chamber in the fifth example. [Figure 21] Figure 21 shows the trimmed active-on waveform applied to the active-on fluid chamber in the fifth example. [Figure 22] Figure 22 shows an example of an inactive actuator waveform applied to an inactive fluid chamber adjacent to an active ON fluid chamber in the fifth example. [Figure 23]Figure 23 shows an example of an active-off actuator waveform applied to an active-off fluid chamber in the fifth example. [Figure 24] Figure 24 shows an example of an inactive actuator waveform applied to an inactive fluid chamber adjacent to an active OFF fluid chamber in the fifth example. [Figure 25] Figure 25 shows an example of the difference in potential waveforms applied to the individual actuator walls of the active ON fluid chamber in the fifth example. [Figure 26] Figure 26 shows an example of the difference in potential waveforms applied to the individual actuator walls of the active-off fluid chamber in the fifth example. [Figure 27] Figure 27 shows a droplet dispensing head of a fifth example that dispenses five droplets. [Figure 28] Figure 28 shows the waveform applied to the electrode of the fifth example to produce the discharge shown in Figure 26. [Figure 29] Figure 29 shows a set of trimming options for flexibly adjusting the actuator signal. [Figure 30] Figure 30 shows an example of a joint drive waveform with discharge and non-discharge waveforms, and an example of a trimmed drive waveform with four transitions between joint drive waveforms. [Modes for carrying out the invention]

[0078] This embodiment illustrates several examples of putting the present invention into practice. However, these are not the only ways in which the present invention can be realized. For example, it is clear that there are many options even for the timing of a single transition between common drive waveforms for supplying a trimming signal to an actuator. When multiple transitions are considered, the number of options increases further. Several examples are given below to illustrate these various applications, but those skilled in the art will understand that the embodiments described herein are a subset of the general concepts contained in the appended claims. In particular, aspects of one example below can be readily combined with others. To give a more specific example, the specific example below shows that the trim occurs in one direction (i.e., switching from a first common drive waveform to a second common drive waveform at a particular time), but this disclosure is to be interpreted as also encompassing a similar transition in the reverse direction, i.e., switching from a second common drive waveform to a first common drive waveform at a similar timing (wherein "similar" is used to indicate that the transitions do not necessarily occur simultaneously, but are considered to occur in the same portion of the waveform). Embodiments described herein relate to the control of a droplet dispensing device for providing consistent droplet dispensing while reducing heat generation in or near the droplet dispensing head. This is typically achieved by comprising at least two common drive waveforms and a waveform selector configured to selectively couple one of the two common drive waveforms to an actuator. The timing of the transitions between the common drive waveforms results in different output signals, known as trimming.

[0079] A droplet dispensing device may have multiple actuators, each actuator possibly associated with at least one fluid. Each actuator may have an actuator wall sandwiched between two electrodes. The systems and methods described herein facilitate a method for providing different outputs (i.e., waveforms tuned in different ways) to different electrodes of an actuator as needed. In some cases, the system can supply different waveforms to each electrode, each electrode receiving individually trimmed drive waveforms generated by transitions between two or more common drive waveforms at a time specific to its actuator. These individually trimmed drive waveforms control droplet dispensing and provide consistent dispensing across multiple chambers. As previously mentioned, the optimal tuning for a particular actuator / chamber can be determined by empirical, computational, or iterative investigation procedures.

[0080] Figures 1 to 4 illustrate various aspects of the first example. Figure 1 shows the connection of the waveform selection unit 330 to two actuators 140. The droplet dispensing head 100 comprises a plurality of fluid chambers 130a to 130c. Each fluid chamber is provided with nozzles 137a to 137c from which the fluid in the fluid chamber is dispensed. Each fluid chamber is elongated in the chamber length direction perpendicular to the array direction x. Adjacent fluid chambers in the array are separated by actuator walls 141, 142 or actuator 140. These actuator walls 141, 142 or actuator 140 may be formed of a piezoelectric material such as lead zirconate titanate (PZT) or a similar material that deforms when a potential difference is applied. One longitudinal side of each fluid chamber 130a to 130c is (at least partially) separated by a nozzle plate, which provides nozzles 137a to 137c to each of the fluid chambers 130a to 130c. Each chamber actuator wall 141, 142 is sandwiched between electrodes 131a and 131b, and 132b and 132c. Electrodes 131a and 131b, and 132b and 132c are configured to apply individual drive waveforms to the actuator walls 141, 142.

[0081] The waveform selection unit 330 is connected to electrodes 131a, 131b, 132b, and 132c of the actuator walls 141 and 142. In this example, the waveform selection unit 330 selects two common drive waveforms 411, 412 or 421, 422 to be applied to each actuator wall 141 and 142. Common drive waveforms 411 and 412 are applied to the first electrode 131b, and common drive waveforms 421 and 422 are applied to the second electrode 131a, as will be described in more detail below.

[0082] Figure 2 shows examples of four common drive waveforms 411, 412, 421, and 422 applied to the first electrode 131b and the second electrode 131a by the waveform selection unit 330. Here, it can be seen that each common drive waveform has a first pulse and a second pulse. Furthermore, each common drive waveform starts and ends at the baseline voltage V0, and its amplitude increases up to the initial maximum value of that common drive waveform (the amplitude is interpreted as pointing to |V-V0|, as part of the waveform increases in the positive direction and part increases in the negative direction). This initial maximum value is maintained in the first part of the common drive waveform. At the end of the first part, each common drive waveform transitions to a second part. Here, the common drive waveform, which was initially negative (relative to V0), passes through V0 and becomes positive, and vice versa. Each common drive waveform transitions to a new amplitude and maintains that amplitude for the duration of the second section. At the end of the second section, each common drive waveform returns to V0, and a printing cycle can be repeated, for example.

[0083] In the illustrated example, the initial maximum amplitude of the first pulse 411a of the common drive waveform 411 is V1, and the maximum amplitude of the second pulse 411b is V3. Similarly, the initial maximum amplitude of the first pulse 412a of the common drive waveform 412 is V2, and the maximum amplitude of the second pulse 412b is V4. Furthermore, it can be seen that the initial maximum amplitude of the first pulse 421a of the common drive waveform 421 is V4, and the maximum amplitude of the second pulse 421b is V2. Finally, the initial maximum amplitude of the first pulse 422a of the common drive waveform 422 is V3, and the maximum amplitude of the second pulse 422b is V1. In all cases, V1 > V2 > V0 > V3 > V4, meaning that V1 and V2 are positive with respect to the reference voltage V0, and V1 is higher than V2. Similarly, V3 and V4 are negative with respect to the reference voltage V0, and V4 is lower than V3.

[0084] In this example, the following steps and waveforms shown in Figures 3 and 4 are performed to dispense droplets.

[0085] Figure 3 is a waveform diagram of the adjusted drive waveform 711 applied to the first electrode 131b. First (Figure 3, step a), the waveform selection unit 330 selects the common drive waveform 411 to be applied to the electrode 131b for the individual drive waveform 711, i.e., the adjusted drive waveform 711. In step b of Figure 3, the adjusted drive waveform 711 follows the common drive waveform 411, and the voltage of the adjusted drive waveform 711 increases from the baseline voltage V0 to the maximum voltage V1.

[0086] Next (Figure 3, step c), while the common drive waveform 411 is V1, the waveform selection unit 330 switches from selecting and applying the common drive waveform 411 to selecting and applying the common drive waveform 412 and applying it to the first electrode 131b. As a result, the voltage applied to the first electrode 131b decreases from V1 (transmitted by the common drive waveform 411) to V2 (transmitted by the common drive waveform 412) and remains at V2 for a while. The switching timing is not fixed but is adjustable as shown by the shaded area in Figure 3. The shaded area indicates the applicable trimming amount. This effectively creates a ledge or shoulder (between steps b and c in Figure 3) in the waveform applied to the actuator, and by adjusting this, the required discharge parameters can be adjusted to obtain the desired effect. If trimming is not required, the trimmed drive waveform 711 follows the common drive waveform 412.

[0087] Next, in step d of Figure 3, the trimmed drive waveform follows the common drive waveform 412, and the voltage of the trimmed drive waveform decreases from V2 to V4 (see Figure 2 as the second pulse 412b of the common drive waveform). At this stage, droplets are ejected from the nozzle 137b. It should be noted that, in order to eject droplets from the nozzle 137b, a waveform such as 0 volts, a reference voltage V0, or 712 in Figure 4 can be applied to the other electrode 132b. Alternatively, the other electrode 132b can be considered to be held at a fixed voltage relative to the first electrode 131b by the waveform selection 330.

[0088] In step e of Figure 3, the trimmed drive waveform 711 maintains a voltage of V4. While the voltage of the trimmed drive waveform 711 is V4, the waveform selection unit 330 switches from selecting and applying the common drive waveform 412 to selecting and applying the common drive waveform 411, thereby generating a substantial ledge in the trimmed drive waveform 1 according to the trimming requirements.

[0089] As a result, the voltage applied to the first electrode 131b rises from V4 (carried by the common drive waveform 412) to V3 (carried by the common drive waveform 411) and remains at V3 for a while. The switching timing is not fixed but adjustable, as shown in step g of Figure 3, providing further adjustment options. If no adjustment is required, the trimmed drive waveform 711 simply follows the common drive waveform 411.

[0090] Finally, the voltage of the trimmed drive waveform 711 remains at V3 for a while before rising back to V0. Thus, in this example, the common drive waveforms 411 and 412 can be used to generate a trimmed drive waveform.

[0091] In the example above, only the area enclosed by the diagonal lines is generated on the head, thus keeping the heat source away from the droplet ejection head. In particular, by shifting the complexity of generating the two waveforms outside the head, the heat generated on the head can be minimized as much as possible. The fluid chamber-specific transitions that occur on the head are simply the switching of two common drive waveforms at timings determined by the trimming signal.

[0092] Figure 4 shows an example of a trimming drive waveform 712 that can be applied to the second electrode 131a. Essentially, this waveform 712 is an inverted waveform of the trimming drive waveform 711 shown in Figure 3, i.e., it is the same trimming drive waveform 711 but inverted along the V0 axis, which changes the potential difference between the first electrode 131b and the second electrode 131a, deforming the corresponding chamber wall and causing droplets to be ejected from the nozzle. The common drive waveforms 421 and 422 shown in Figure 2 are inverted waveforms of the common drive waveforms 411 and 412, and it can be seen that these common drive waveforms are actually used to generate the trimming drive waveform 712 that is applied to the second electrode 131a.

[0093] In other words, as shown in Figure 4, the waveform selection unit 330 selects the common drive waveform 421 and the common drive waveform 422 and applies them to the second electrode 131a in the following manner.

[0094] First, as shown in step h of Figure 4, the common drive waveform 421 is selected as the trimming drive waveform 712 and applied to the second electrode 131a. In this step, the trimming drive waveform 712 follows the common drive waveform 421, and the voltage of the trimming drive waveform 712 decreases from V0 to V4. In step i of Figure 4, the trimming drive waveform 712 is held at V4, which is the maximum voltage of the common drive waveform 421.

[0095] Next (Figure 4, step j), while the trimmed drive waveform 712 is V4, the waveform selection unit 330 switches from selecting and applying the common drive waveform 421 to selecting and applying the common drive waveform 422, thereby substantially generating a ledge in the trimmed drive waveform 712 applied to the second electrode 131a. As a result, the voltage applied to the second electrode 131a rises from V4 (carried by the common drive waveform 421) to V3 (carried by the common drive waveform 422) and remains at V3 for a period of time. The switching timing is not fixed but adjustable, as indicated by the diagonal lines showing the difference in applicable trimming amounts. This effectively generates a ledge or shoulder (between steps i and j in Figure 4) in the trimmed drive waveform 712 applied to the second electrode 131a, which can be adjusted to suit the discharge parameters necessary to achieve the desired effect.

[0096] Next, in step k of Figure 4, the trimmed drive waveform 712 follows the common drive waveform 422, and the voltage increases from V3 to V1 (the second pulse 422b of the common drive waveform 422 shown in Figure 2).

[0097] In step l of Figure 4, the trimmed drive waveform 712 maintains a voltage V1 for a period of time. Next, in step m of Figure 4, while the trimmed drive waveform 712 is at voltage V1, the waveform selection unit 330 switches from selecting and applying the common drive waveform 422 to selecting and applying the common drive waveform 421, thereby creating a substantial ledge in the trimmed drive waveform 712 applied to the second electrode 131a. In this step, the voltage applied to the second electrode 131a decreases from V1 (carried by the common drive waveform 422) to V2 (carried by the common drive waveform 421) and maintains V2 for a period of time. The switching timing is not fixed but adjustable according to the trimming requirements, which is shown in the shaded area.

[0098] Finally, in step n of Figure 4, the trimmed drive waveform 712 remains at V2 for a while before dropping back down to V0. As a result, the voltage applied to the second electrode 131a also decreases.

[0099] Of course, the above configuration is merely an example. For instance, if one actuator wall of the chamber provides enough energy to eject droplets from the nozzle, no potential difference is applied to the other actuator wall of the chamber, and no movement of the actuator wall is observed.

[0100] If both actuator walls of the chamber are required to eject droplets from the nozzle, a potential difference must be applied to both actuator walls. However, this does not mean that the waveform applied to both actuator walls must be trimmed. The waveform can be trimmed both times, one of them, or neither.

[0101] It is also possible to trim the output signal using only one transition between two waveforms. As another example, two transitions may occur: V3=V4 for the first actuator wall of the chamber and / or V1=V2 for the second actuator wall of the chamber, or vice versa.

[0102] Hot switching is observed in the transitions between common drive waveform 411 and common drive waveform 412, and between common drive waveform 421 and common drive waveform 422 (shaded areas in Figures 3 and 4). Cold switching, on the other hand, is observed in all transitions within each common drive waveform (common drive waveform 411, common drive waveform 412, common drive waveform 421, and common drive waveform 422). This is because these changes are provided as part of the common drive waveform itself.

[0103] In steps c, f, j, and m, the shape of the trimming drive waveforms 711, 712 applied to the first and second electrodes 131b, 131a can be controlled by controlling the switching time between the common drive waveforms 411, 412 and the common drive waveforms 421, 422. These trimming drive waveforms 711, 712 are applied to the actuator wall 141, thereby controlling the velocity and / or volume of droplets ejected from the nozzles 137a, 137b. Note that, as mentioned above, to eject droplets from the nozzles, a waveform such as 0 volts or a reference voltage V0, or a waveform like 712 in Figure 4, can be applied to the other electrode. Alternatively, the other electrode can be considered to be held at a fixed voltage relative to electrodes 131b, 131a by the waveform selection unit 330.

[0104] The adjustable drive waveform applied to eject droplets from a single fluid chamber can be adjusted over time to compensate for temperature changes in the actuator wall and aging degradation of the piezoelectric material. Furthermore, by applying different shaped adjustable drive waveforms to two different actuator walls based on the same common drive waveform, and by providing different protrusions (ledges) to each, the volume and / or velocity of droplets ejected between the two nozzles can be made uniform.

[0105] Figure 5 shows another example of a drive circuit 300 that supplies a trimmed drive waveform to at least one electrode, thereby causing the corresponding fluid chamber to eject droplets from the corresponding nozzle. The drive circuit 300 comprises at least one waveform selector 330, which is configured to receive a first common drive waveform (CDW) 411, a second common drive waveform (CDW) 412, a print signal 322, and a switching timing 331. The waveform selector 330 is configured to output a selected common drive waveform. Furthermore, the waveform selector is configured to switch between selecting and applying the first common drive waveform 411 and the second common drive waveform 412 based on the switching timing 331, thereby effectively coupling at least one electrode 131b to a trimmed drive waveform 711 that may be partially formed by the first common drive waveform 411 and the second common drive waveform 412. The print signal 322 is configured to indicate whether a dot is to be printed on a particular pixel by a particular nozzle. For example, if a dot is not printed on a particular pixel, the waveform selection unit 330 may isolate the electrode 131b from the first common drive waveform 411 and the second common drive waveform 412 for the duration of the printing cycle, so that no drive waveform is generated for that particular pixel of the image. Each waveform selection unit 330 may include at least two switching circuits 310a, 310b that switch between two or more common drive waveforms. It should be noted that the switching circuits may be part of the waveform selection or they may be separate circuits. If they are separate circuits, the waveform selection unit sends and receives signals to and from the switching circuits.

[0106] Furthermore, the drive circuit 300 may include a timing circuit 320 that generates a switching timing 331 upon receiving a trimming signal 321. The trimming signal 321 indicates the amount of trimming required for a particular actuator. There are many possible ways in which the timing circuit 320 generates the switching timing 331 and controls the switching between the first and second common drive waveforms 411 and 412. For example, the switching timing 331 can be synchronized to an internal clock, the level of the common drive waveform, or other timing references.

[0107] The drive circuit 300 may further include a controller 350 configurable to generate a print signal 322 and a trimming signal 321 from a data signal 351 and a clock signal (CLK) 352. In another example, each actuator wall may have one electrode electrically connected to a common signal. Figure 6 shows electrodes 131b and 132b connected to the common signal Vref. This common signal may be a constant signal or a time-varying signal depending on a desired voltage profile over time measured across each actuator wall. On the other hand, electrodes 131a and 132c may be supplied with trimmed drive waveforms as shown in Figures 3 and 4. This means that instead of the drive circuit selecting and applying a common drive waveform to the walls, a waveform selection circuit selects and applies common drive waveforms 411 and 412, or 421 and 422, to electrodes 131a and 132c, respectively. Thus, the waveform applied to each actuator wall is the output waveform of the waveform selection circuit minus this common signal.

[0108] Figure 6 shows another example of two drive circuits 301a and 301c, each comprising the following elements: - Waveform selectors 330a, 330c are configured to select at least two common drive waveforms (CDWs) 411 and 412 or 421 and 422 based on print signals 322a, 322c and trimming signals 321a, 321c, and to couple one or more electrodes 131a, 132c to the selected common drive waveforms (CDWs) 411 and 412 or 421 and 422 selected by the waveform selector 330; - Timing circuits 320a and 320c for controlling waveform selections 330a and 330c.

[0109] The waveform selection units 330a and 330c are each equipped with switching circuits 310a and 310b. Each switching circuit 310a and 310b receives a common drive waveform 411 and 412 as input. The switching circuits 310a and 310b are controlled by switch control based on print signals 322a and 322c and a switching timing signal 331. Figure 6A shows an example of the arrangement of the switching circuits in the waveform selection unit of Figure 6.

[0110] Timing circuits 320a and 320c are configured to receive trimming signals 322a and 322c. Timing circuits 320a and 320c are configured to control the timing of the transition between the first common drive waveform and the second common drive waveform by the waveform selection circuits 330a and 330c, and to perform trimming.

[0111] Therefore, as described above, the waveform selection units 330a and 330c apply trimmed drive waveforms, consisting of a portion of the first common drive waveform and a portion of the second common drive waveform, to the respective electrodes 131a and 132c. The printing signals 322a and 322c are configured to indicate whether to print a dot on a specific pixel by a specific nozzle. For example, if ejection is not required, no signal is transmitted. In other cases, even when ejection does not occur, waveforms are transmitted, for example, to cancel induced motion of the actuator wall from an adjacent fluid chamber, or to maintain constant fluid movement so that the fluid does not block the nozzle of the fluid chamber during chamber downtime.

[0112] Next, we move to Figures 7 and 8, which show a second example. Figure 7 shows a schematic diagram of the electrical connections to electrodes 121a-121c on actuator walls 140-143. Fluid chambers 130a-130c are separated by actuator walls 140-143. Each fluid chamber 130a-130c has a single electrode 121a-121c arranged along its respective fluid chamber 130a-130c. This electrode configuration is not necessarily required for the application of the waveforms disclosed herein, because the same effect can be achieved by placing individually addressable electrodes on each actuator wall, as shown in Figure 1, with appropriate modifications to the electronic equipment to which the waveforms are applied.

[0113] The common drive waveforms 411, 412, 421, and 422 in Figure 2 can be applied to electrodes 121a to 121c corresponding to actuators 130a, 130b, and 130c, but the application method needs to be adjusted. Here, instead of applying the common drive waveforms 411, 412, 421, and 422 to two separate electrodes in order to deform the chamber wall and eject droplets from the nozzle, the common drive waveforms 411, 412, 421, and 422 are applied to a continuous set of electrodes 121a, 121b, and 121c.

[0114] Figure 8 shows an example of a combined voltage 721 applied to the first actuator wall 141 to eject droplets from fluid chambers 130a and 130b. First, in step o, at some point during the V0 holding period, the drive circuit 301b couples a common drive waveform 411 to electrode 121b, and the drive circuit 301c couples a common drive waveform 421 to electrode 121c.

[0115] At some point, the voltage of the common drive waveform 411 increases from V0 to V1 and remains at V1, while the voltage of the common drive waveform 421 decreases from V0 to V4 and remains at V4. As a result, as shown in steps p and q of Figure 8, the voltage across the first actuator wall 141 increases from V0 to V1-V4 and remains at V1-V4. Next (Figure 8, step r), during the holding period of both common drive waveforms 411 and 421, the drive circuit 301b switches from applying the common drive waveform 411 to applying the common drive waveform 412, while the drive circuit 301a switches from applying the common drive waveform 421 to applying the common drive waveform 422.

[0116] As a result, the voltage across the first actuator wall 141 decreases from V1-V4 to V2-V3 and remains at V2-V3 for a period of time. The switching timing is not fixed but adjustable, as indicated by the shaded area, which shows the difference in applicable trimming amounts. This creates a ledge or shoulder in the waveform applied to the actuator, and by adjusting this, the required discharge parameters can be tuned to achieve the desired effect.

[0117] Next, the voltage of the common drive waveform 412 drops to V4 and the voltage of the common drive waveform 422 rises to V1, so the voltage across the first actuator wall 141 becomes V4-V1 and is maintained at this new potential difference for a while (steps s and t in Figure 8). Then, as shown in step u in Figure 8, during the holding period of both the common drive waveforms 412 and 422, the drive circuit 301b switches from applying the common drive waveform 412 to applying the common drive waveform 411, and the drive circuit 301a switches from applying the common drive waveform 422 to applying the common drive waveform 421.

[0118] As a result, the potential difference applied to the first actuator wall 141 of the fluid chambers 130a and 130b decreases from V4-V1 to V3-V2, and this potential difference is maintained for a certain period of time. The switch timing is not fixed but adjustable, as shown in step u of Figure 8, providing further adjustment options.

[0119] Finally, the common drive waveform 411 increases from V3 to V0, the common drive waveform 421 decreases from V2 to V0, and the voltage across the first actuator wall 141 decreases from V3-V2 to V0.

[0120] It should be noted that the trimming drive waveform applied to electrode 121c may be an inverted waveform of the trimming drive waveform applied to electrode 121b. Also, the common drive waveform applied to electrode 121c by the drive circuit 301c is the same as the common drive waveform applied to electrode 121a.

[0121] Further examples can be seen by changing the number of common drive waveforms input to each waveform selection. For example, it is possible to apply a trimmed conventional 3-cycle waveform. In such an example, the fluid chambers to which each actuator is associated are arranged in three groups designated A, B, and C, and each set of three adjacent fluid chambers contains at least one of each of the A, B, and C fluid chambers. The fluid chambers are arranged in the same order as the actuators belonging to each of the three groups, forming a repeating pattern, for example, ...ABCABC...

[0122] Furthermore, each print cycle has three subcycles: A subcycle, B subcycle, and C subcycle. In each subcycle, fluid chambers with specifications that do not match the subcycle specification are designated as inactive fluid chambers. Only fluid chambers with specifications that match the subcycle specification are assigned as active fluid chambers. In other words, an "A" fluid chamber can only eject droplets in the "A" subcycle, and the same applies to the "B" and "C" fluid chambers / subcycles. Fluid chambers with specifications that match the subcycle specification are further assigned as active ejecting fluid chambers or active non-ejecting fluid chambers depending on the ejection signal. That is, even active fluid chambers do not always eject droplets, but only based on a print signal (or ejection signal) indicating whether ejection is required during that subcycle.

[0123] In this 3-cycle printing mode, conventionally, at least three common drive waveforms must be applied sequentially to the actuator. Active ON waveform - A waveform applied to the active discharge fluid chamber, which discharges droplets from the corresponding nozzle in a specified subcycle. Active OFF waveform - A waveform applied to an active non-discharge fluid chamber, resulting in the absence of droplet discharge from the corresponding nozzle for a predetermined subcycle. Inactive - A waveform applied to an inactive fluid chamber that cannot be discharged within a specific subcycle.

[0124] Figure 9 shows a block diagram illustrating the two drive circuits 302a and 302b in the example shown in Figure 7, and the corresponding connections to the electrodes of the actuator wall 141. Each drive circuit 302a and 302b includes timing circuits 320a and 320b. Each drive circuit 302a and 302b in Figure 9 also includes waveform selection circuits 330a and 330b configured to select at least four common drive waveforms to be applied to each electrode 121a, 121b, or 121c. In this example, the timing circuits 320a and 320b are configured to control the timing at which the waveform selection circuits 330a and 330b select one of the common drive waveforms (CDWs) 511 to 514 and output that common drive waveform (CDW) to the electrodes 121a, 121b, and 121c of the fluid chambers 130a and 130b.

[0125] The waveform selection units 330a and 330b each include switching circuits 310a, 310b, 310c, and 310d, respectively. Each switching circuit 310a, 310b, 310c, and 310d receives common drive waveforms 511, 512, 513, and 514 as input. The switching circuits 310a to 310d are controlled by switch control based on the print signal 322a and the switching timing signal 331. Figure 9A shows an example of the arrangement of the switching circuits in the waveform selection unit of Figure 9.

[0126] In this example, at least four common drive waveforms are used to trim in the same manner as described above, input to each waveform selector 330a, 330b. These are one common inactive waveform 513 shown in Figure 11, one common active OFF waveform 514 shown in Figure 12, and two common active ON waveforms 511 and 512 shown in Figure 10. Alternatively, in this example, at least three common drive waveforms are used to trim in the same manner as described above, so the common inactive waveform 513 is not necessary, and the common active OFF waveform 514 functions as a common inactive waveform as needed.

[0127] In either case, based on the print signals 322a and 322b and the signals from the timing circuits 320a and 320b, the waveform selection units 330a and 330b select one of the common drive waveforms and output it to the respective electrodes of the fluid chambers 130a and 130b.

[0128] Figure 10 also shows an example of a common active-on drive waveform used in this example. Figure 11 shows an example of a common inactive drive waveform used in an inactive fluid chamber. Figure 12 shows an example of a common active-off drive waveform used in an active-off fluid chamber. Figure 15 shows an example of a trimmed drive waveform 811, drawn with the time transitions between the common drive waveforms in Figure 10, for supplying the electrodes of an active-on actuator.

[0129] Assuming that the nozzle 137b of the fluid chamber 130b is discharged during a subcycle, the following process is performed. The common drive waveform applied to the electrode 121a of the fluid chamber 130a and the electrode 121c of the fluid chamber 130c is a common inactive drive waveform 514, as shown in Figure 11. This is because during a subcycle, the only active fluid chamber is the fluid chamber of the same subcycle as fluid chamber 130b, and due to the aforementioned subcycle assignment, adjacent actuators must be part of different subcycles. To perform trimming, the waveform selection unit 330b selects one of two common active-on drive waveforms 511, 512 based on the signal output from the timing circuit 320b and applies it to the electrode 121b of the fluid chamber 130b. Also, during the subcycle, based on the signal output by the timing circuit 320b, the waveform selection unit 330b switches from selecting and applying one common active-on drive waveform to the electrode 121b of the fluid chamber 130b to selecting and applying the other common active-on drive waveform.

[0130] Figure 13 shows examples of switching circuits 310a and 310b included in the waveform selection unit 330, as shown in Figure 5. Switching circuits 310a and 310b can each be viewed as composite path gates containing four transistors connected in a specific arrangement. Figure 14 shows a simplified internal resistance of each transistor shown in Figure 13. M1B and M2B are designed with a large width / length (W / L) ratio and low on-resistance, while M1A and M2A are designed with a small W / L ratio and high on-resistance to reduce the slew rate of transitions between waveforms. M1B and M2B are controlled by a single timing circuit 320a, while M1A and M2A are controlled by an independent second timing circuit 320b.

[0131] As shown in Figure 15, during cold switching, M1B / M2B and M1A / M2A are turned on. This is because the resistance of the composite pass gate is approximately 2R. LOW It means that. R COLD =RM1A / / R M1B +R M2B / / R M2A Here, the internal resistance of M1A is in parallel with the internal resistance of M1B, and the internal resistance of M2B is in parallel with the internal resistance of M2A. R LOW / / R HIGH ≈R LOW And R COLD =R LOW +R LOW ≈2R LOW During hot switching, M1B and M2B are off, and M1A / M2A are on. Therefore, the total resistance of the composite path gate is approximately 2R HIGH becomes. R HOT =R M1A +R M2A =R HIGH +R HIGH ≈2R HIGH。

[0132] The switching circuits 310a and 310b include a high-resistance path used during hot switching and a low-resistance path used during cold switching. The high-resistance path is configured to enable the transition from the first common drive waveform to the second common drive waveform. The timing circuits 320a and 320b are configured to control the switching between the high-resistance path and the low-resistance path.

[0133] The low resistance of the path gate minimizes power consumption, and the high resistance of the path gate minimizes the peak current flowing through the path gate. For example, during cold switching, the current is mainly determined by the slew rate of the drive waveform and the load capacitance of the actuator. Therefore, the lower the resistance, the lower the power consumption. During hot switching, the peak current is determined by the switch resistance and the voltage difference between the two waveform sources during switching. Therefore, a higher resistance is desirable to limit the peak current.

[0134] Figure 15 shows the procedure for generating an adjustable drive waveform 811 that can be applied in subcycles to one of the fluid chambers in the active ON state via the switching circuits 310a and 310b of the waveform selection unit 330. These switching circuits 310a and 310b can be, for example, the composite path gates shown in Figure 13. As will be described later, this type of switching circuit can be used, but is not limited to this, and in other examples, more basic switching circuits may be used.

[0135] At t1 (step a), during the V0 holding period, the transistor pairs M1B / M2B and M1A / M2A of the switching circuit 310a are turned on, and a common active-on drive waveform 511 is applied to the electrode 121b of the fluid chamber 130b. While M1B / M2B and M1A / M2A are turned on, between t1 and t2 (step b), the trimming drive waveform 811 applied to the electrode 121b of the fluid chamber 130b follows the common active-on drive waveform 511, and the voltage rises from V0 to V1 and is then held at V1.

[0136] Around t2 (step c), the transistor pair M1B / M2B and M1A / M2A of switching circuit 310a are turned off, preparing to switch between the common active ON drive waveform 511 and the common active ON drive waveform 512. Next, the transistor pair M1A / M2A of switching circuit 310b are turned on, and the waveform selector 330b begins outputting the common active ON drive waveform 512. This waveform 512 is output to the electrode 121b of the fluid chamber 130b via the high-resistance transistors M1A / M2A of switching circuit 310b. This increases the overall resistance of the switch, protecting the circuit from high peak current during waveform switching. Therefore, the trimmed drive waveform 811 applied to the electrode 121b of the fluid chamber 130b follows the common active ON drive waveform 512, the voltage decreases from V1 to V2, and then the voltage is held at V2 (t3 、 Step d).

[0137] Between t4 and t5 (step e), M1B / M2B of the switching circuit 310b are turned on, while M1A / M2A remain on. The voltage of the common active ON drive waveform 512 drops to V4 and is maintained at V4 for a certain period of time. Subsequently, the voltage rises to V3 (i.e., the negative value relative to V0 becomes smaller) and is maintained at V3 for a certain period of time. The trimmed active ON waveform 811 applied to the electrode 121b of the fluid chamber 130b follows the common active ON drive waveform 512.

[0138] Around t5 (step f), the M1B / M2B and M1A / M2A transistors of switching circuit 310b are turned off, preparing to switch from the common active-on drive waveform 512 to the common active-on drive waveform 511. Next, the transistor pair M1A / M2A of switching circuit 310a are turned on, and the waveform selection circuit begins outputting the common active-on drive waveform 511. This waveform is output to the electrode 121b of the fluid chamber 130b via the high-resistance transistors M1A / M2A of switching circuit 310a. This increases the overall resistance of the switch, protecting the circuit from high peak currents. Thus, the trimmed drive waveform 811 applied to the electrode 121b of the fluid chamber 130b follows the common active-on drive waveform 511, and the voltage drops to V4 and is then held at voltage V4 (t6, step g).

[0139] Finally, between t7 and t8 (step h), M1B / M2B of the switching circuit 310a are turned on again, while M1A / M2A remain on. The common active ON drive waveform 511 remains at V4 for a certain period of time, and then rises to V0. The trimmed active ON waveform 811 applied to the electrode 121b of the fluid chamber 130b follows the common active ON drive waveform 511.

[0140] It will be understood that by controlling the switching timing of each transistor pair, it is possible to control part of the transition timing, and in particular, to change the trimming applied to each signal.

[0141] Switching circuits 310a and 310b may be briefly switched off before and after a transition between common drive waveforms occurs, in order to prevent damage to the switching circuits from unwanted currents flowing between the two switches when a transition between common drive waveforms occurs.

[0142] For integrity, the nozzle 137b of fluid chamber 130b is assumed not to discharge during its subcycle. In this case, the common drive waveform applied to the electrodes 121a of actuators 130a and 130c is a common inactive drive waveform as shown in Figure 11, and is applied via the switching circuit 310c of waveform selectors 330a and 330b. This is because during the subcycle, the only active fluid chamber is the fluid chamber of the same subcycle as fluid chamber 130b. The common drive waveform applied to the electrode 121b of fluid chamber 130b is a common active-off drive waveform as shown in Figure 12, and is applied via the switching circuit 310d of waveform selector 330b.

[0143] Figure 16 shows two examples of differently trimmed active-on waveforms that can be applied to the electrode 121b of the fluid chamber 121b of the discharge fluid chamber 130b, based on the active-on common drive waveform of Figure 10. In other words, by controlling the switching time between the common active-on drive waveform 511 and the common active-on drive waveform 512, the shape of the output waveform can be effectively controlled, thereby providing an output with different trimmed drive waveforms. A slow transition between the common active-on drive waveform 511 and the common active-on drive waveform 512 means that the pulse P01 is large and the ledge L11 is small (T1 TRIM This means that the pulse P01' is small and the ledge L11' is large (T1 TRIMThis means that (the volume / velocity of the droplets discharged from the fluid chamber 130 is large). This allows for increasing or decreasing the volume / velocity of the droplets discharged from the fluid chamber 130. A similar idea applies to pulses P02, P02', ledges L12, L12', and T2 TRIM This also applies. This can be thought of as the timing circuit being configured to output trimming timing signals during the attraction, release, or enhancement phases of the common drive waveform. Referring to Figure 15, the attraction phase is roughly steps a to c, the release phase is roughly steps d and the first part of step e, and the enhancement phase is steps e to g and the first part of step h. The cancellation phase begins with the transition to V0 in step h and continues until returning to V0.

[0144] There are numerous ways to generate the timing that controls the duration, such as synchronizing with an internal clock, waveform level and slope, or some other timing reference. To compensate for differences between drive elements, and in some cases to compensate for parameters that change over time, such as temperature, aging, and crosstalk from adjacent pixels, a trimming signal is applied to switch the waveform of each actuator, effectively applying the trimmed drive waveform. The trimming signal can be generated, for example, from a lookup table, generated by a processor based on measured values ​​such as output and temperature, generated from information such as manufacturing calibration results and printed image information, or from a combination of these.

[0145] Figures 17 to 19 show a third embodiment system that reuses the concepts of active and inactive fluid chambers. However, while the designation of a particular fluid chamber as inactive was temporary in the previous examples, here the designation is permanent. In some examples, such as those shown in Figure 17, the alternately arranged fluid chambers 134 are blocked and unable to discharge droplets. In other examples, these fluid chambers are not supplied with any discharge waveform at all. In all cases, the inactive fluid chambers 134 are alternately arranged such that an active fluid chamber 135 is sandwiched between two inactive fluid chambers 134, and an inactive fluid chamber 134 is sandwiched between two active fluid chambers 135 (excluding, of course, the ends of arrays with only one boundary).

[0146] Figure 18 shows an example of a common drive waveform used in this example to provide a trimmed drive waveform to the electrodes of the active fluid chamber. As in the previous example, common drive waveforms 511 and 512 are used to generate trimmed drive waveforms 811 and 811' that are applied to the actuator by timing control between the two common drive waveforms. The resulting trimmed drive waveform (similar to those described above) can be adjusted by changing the switching timing between the common drive waveforms. In this example, the electrodes of each closed fluid chamber are connected to Vref. Vref can be ground, 0V, or any other known fixed voltage value. The non-discharging fluid chamber of the active fluid chamber 135a receives a common active-off drive waveform to its electrodes, as it is not intended to discharge droplets in this subcycle. The common active-off drive waveform may be, for example, a common drive waveform 512 that does not have enough energy to eject droplets. Of course, in other examples, a different common drive waveform than the example in Figure 18 may be applied as the common active-off drive waveform. As shown in Figure 19, the adjusted drive waveforms applied to the electrodes of fluid chambers 135b and 135c are 811' and 811, respectively.

[0147] Figure 19 shows examples of trimmed drive waveforms formed using different trimming options based on the waveform in Figure 18. Here, it is shown that different timings for switching between the suction and reinforcement phases result in distinctly different signals supplied to the electrodes in the fluid chamber.

[0148] All the waveforms described so far have been bipolar common drive waveforms with at least one positive pulse and at least one negative pulse (i.e., one pulse with an amplitude higher than the reference voltage V0 and one pulse with an amplitude lower than the reference voltage V0). However, it is also possible to use a unipolar waveform (i.e., a waveform with pulse amplitudes greater than the reference voltage) to control the actuator wall of a fluid chamber. The theory here is that since the waveform can be applied to either side of the actuator wall, a negative pulse on one side of the actuator wall acts like a positive pulse on the other side of the actuator wall. This simplifies the supplied signal because signal inversion is not required. Instead, it is only necessary to adjust the waveform selection to couple the same signal to the electrodes on the opposite side of the actuator wall.

[0149] Figure 20 shows an example of a unipolar common drive waveform applicable to a 3-cycle eject mode operating in the order C→B→A. Figure 21 shows the corresponding trimmed active-on drive waveform 911, and Figure 22 shows an example of an inactive-on drive waveform 912. An example of an active-off drive waveform 913 is applied to an inactive fluid chamber adjacent to an active-on fluid chamber. Figure 23 shows an example of an active-off drive waveform 912 applied to an active-off fluid chamber, and Figure 24 shows an example of an inactive drive waveform 914 applied to an inactive fluid chamber adjacent to an active-off fluid chamber. Finally, Figures 25 and 26 show the difference waveforms 1010 and 1011 (i.e., the voltage difference applied across the actuator wall) for the active-on and active-off fluid chambers, respectively. Figures 27 and 28 show how these waveforms are used when ejecting droplets, illustrating the droplet ejection head with the attached droplets and the signals applied to various electrodes to achieve this, respectively.

[0150] Now, let's consider Figure 27, which shows a droplet ejection head actuator operating in CBA3 cycles and ejecting five droplets along the pixel line to be printed. The droplet ejection head starts ejecting during the printing cycle, i.e., the time interval T during which each fluid chamber has an opportunity to eject a droplet in response to the printing signal. Here, the process starts from subcycle C, and in particular fluid chambers 130c_1 and 130c_2 are ejection fluid chambers (active ON) and eject droplets D1.1 and D1.2 almost simultaneously. All other fluid chambers are inactive fluid chambers in this subcycle, as they are fluid chambers A and B.

[0151] Next, subcycle B is activated. In this subcycle, fluid chamber 130b_1 is a non-discharge fluid chamber and does not produce droplets (active OFF). On the other hand, the fifth fluid chamber 130b_2 is a discharge fluid chamber (active ON) and, like fluid chambers 130c_1 and 130c_2 above, discharges droplet D2.1. All other fluid chambers are A and C fluid chambers and are therefore inactive fluid chambers in this subcycle.

[0152] Finally, in subcycle A, fluid chambers 130a_1 and 130a_2 become discharge fluid chambers (active ON) and discharge droplets D3.1 and D3.2 almost simultaneously. Fluid chamber 130a_3 is a non-discharge fluid chamber, so no droplets are generated (active OFF). The other fluid chambers are fluid chambers B and C, and are therefore inactive fluid chambers in this subcycle.

[0153] The details of the discharge / deposit procedure are the same as those described above, so a detailed explanation will not be repeated here.

[0154] To achieve the ejection pattern shown in Figure 27, the signals shown in Figure 29 are applied to the electrodes of each fluid chamber. In particular, the total time T during which a complete printing cycle is possible (i.e., the sum of the execution times of each subcycle A, B, and C) is divided into three parts, each representing (in order) the C, B, and A subcycles. The waveform supplied to the electrodes of the C fluid chamber is shown at the top of the figure, the waveform supplied to the electrodes of the B fluid chamber is shown in the middle, and the waveform supplied to the electrodes of the A fluid chamber is shown at the bottom. When the fluid chamber is inactive, a simple trapezoidal waveform is applied to the actuator. This provides a known background and helps reduce crosstalk in the droplet ejection head. Short, adjusted pulses are applied where droplet ejection is required (upper left corner, center, and lower right corner). Due to the unipolarity of the system, a broad trapezoidal inactive pulse is applied to the actuator wall opposite the active pulse, creating a reinforcement phase between the actuator walls. The active-off pulse is supplied in a similar manner, but is selected so that the differential voltage between the actuator walls is insufficient and ejection is not triggered.

[0155] As mentioned earlier, there are several options for trimming the active ON drive waveform. For example, trimming can be done at the rising or falling edge of each pulse. In other words, trimming can be done at the start of the suction phase, the end of the suction phase / start of the release phase, the start or end of the enhancement phase, etc.

[0156] Figure 29 shows an example of a trimmed drive waveform 1020 and a trimmed ledge. As in the previous example, the size of the ledge can be controlled by controlling the switching time between two or more common drive waveforms.

[0157] The inventors have identified several useful considerations when selecting which ledge to use during trimming.

[0158] To control droplet velocity, trimming can be applied to the waveform's attraction (1), release (2), or enhancement (3) phases. At points (1) and (3), overshoot and ringing of the high-voltage waveform must be considered. A system using a waveform amplifier capable of shaping these corners may be able to adequately suppress overshoot and ringing, achieving effective and consistent trimming at these points.

[0159] In the case of a waveform for discharging conductive fluid, trimming can be applied to the reinforced edge (3) or the cancel edge (5). Trimming can also be applied between the edges (4).

[0160] Trimming the cancellation (5) phase limits the effect of the cancellation pulse and may leave residual acoustic noise in the actuator. Trimming this phase is undesirable if similar effects can be achieved in other phases. Of course, in some cases, it may be necessary to trim this phase to achieve the desired effect.

[0161] In the case of low-frequency waveforms, trimming may occur between the suction and discharge phases (similar to the effect shown in (4) of the enhancement phase).

[0162] A voltage signal can be used to amplify the trimming effect by varying one voltage in the common drive waveform during generation.

[0163] Figure 30 shows an alternative configuration. Here, the common drive waveform is separated into a discharge waveform 1001 and a non-discharge waveform 1002. The main difference is the amplitude of these waveforms; the discharge waveform has an amplitude sufficient to discharge droplets, while the non-discharge waveform does not. The switching circuit switches between these two common drive waveforms and performs trimming as described above. This has the advantage that the non-discharge waveform can be coupled to the electrode as a common reference signal or, for example, an active OFF signal, providing reassurance that it will not lead to discharge. This can simplify processes and equipment, for example.

[0164] Figure 30 also shows a further example of a trimmed drive waveform 1003, where the signal is trimmed at four points during the print cycle. In other words, the output signal starts as the first waveform, switches to the second waveform at t=T1, and the first shoulder occurs in the suction phase. At t=T2, the second switch occurs (for simplicity, we assume it returns to the first waveform, but of course, it could also be the third waveform in some cases). The third switch is performed at t=T3. Again, for simplicity, we assume it returns to the second waveform, but it could also be the third or fourth waveform if necessary. This results in a second ledge in the reinforcement phase. The final switch occurs at T4 (again, it returns to the first waveform, or possibly the second, third, fourth, or fifth waveform), and the cancellation phase is performed. It is clear that there is great flexibility in performing each of these trimming steps.

[0165] According to the principles described herein, the waveform is generated outside the head (i.e., away from the droplet ejection head), minimizing heating on the head. Minimal circuitry is provided on the head, such as switching circuits and multiplexers for each control output.

Claims

1. A circuit that controls a plurality of actuators, each actuator being associated with at least one fluid chamber in a droplet dispensing device, An input section that receives a first common drive waveform, a second common drive waveform, and a trimming signal, An output unit that supplies individual drive waveforms to actuators, A waveform selection unit configured to couple the first common drive waveform with the output unit for connection to the first electrode of the actuator, comprising: a waveform selection unit configured to supply the individual drive waveform to one of the selected actuators based on the first common drive waveform, the second common drive waveform, and the trimming signal; The waveform selection unit is further configured to cause a transition from the first common drive waveform to the second common drive waveform by disconnecting the first common drive waveform from the output unit and coupling the second common drive waveform to the output unit, and the transition occurs at a timing determined by the trimming signal.

2. The circuit according to claim 1, wherein the waveform selection unit is further configured to receive two or more trimming signals supplied to the input unit, thereby generating transitions between the common drive waveforms at different timings so that the individual drive waveforms are supplied to each of the plurality of actuators.

3. The circuit according to claim 1, wherein the waveform selection unit is configured to receive a trimming signal specific to each actuator and to cause a transition between common drive waveforms at a timing specific to that actuator.

4. During the first period of the printing cycle, the first common drive waveform is the first voltage V １ The second common drive waveform is maintained at the second voltage V ２ It is maintained, and then, During the second period of the printing cycle, the first common drive waveform is the third voltage V ３ The second common drive waveform is maintained at the fourth voltage V ４ It is maintained, V ３ ga V １ Lower, V ４ ga V ２ A lower circuit according to claim 1.

5. The first and second common drive waveforms include a discharge waveform component and a non-discharge waveform component. The waveform selection unit, in response to the trimming signal, causes a transition between the output waveform component of the first common drive waveform and the non-output waveform component of the second common drive waveform, and / or The circuit according to claim 1, wherein the waveform selection unit causes a transition between the output waveform component of the second common drive waveform and the non-output waveform component of the first common drive waveform in response to the trimming signal.

6. The first common drive waveform is a discharge waveform, and the second common drive waveform is a non-discharge waveform. The circuit according to claim 1, wherein the waveform selection unit causes a transition between the output waveform and the non-output waveform in response to the trimming signal.

7. The circuit according to claim 4, wherein the trimming signal causes a transition from the first common drive waveform to the second common drive waveform during the first period of the printing cycle.

8. The circuit according to claim 4, wherein the second trimming signal causes a further transition from the second common drive waveform to the first common drive waveform during the second period of the printing cycle.

9. The circuit according to claim 7, wherein the trimming signal is a first trimming signal, and the second trimming signal causes a further transition from the first common drive waveform to the second common drive waveform during the second period of the printing cycle.

10. It further includes an additional input section for receiving a third common drive waveform, The circuit according to claim 1, wherein the waveform selection unit is further configured to connect the third common drive waveform to a second output unit for connecting to the second electrode of the actuator.

11. Further comprising another additional input section for receiving a fourth common drive waveform, The waveform selection unit is further configured to connect the third common drive waveform or the fourth common drive waveform to a second output unit for connecting to the second electrode of the actuator. The circuit according to claim 10, which generates a transition between the third common drive waveform and the fourth common drive waveform in response to a third trimming signal.

12. The circuit according to claim 11, wherein the third common drive waveform is an inverted waveform of the first common drive waveform, or the fourth common drive waveform is an inverted waveform of the second common drive waveform.

13. The common drive waveforms each begin and / or end at a reference voltage level, and each has a positive component and a negative component relative to the reference voltage level. The positive component of the first common drive waveform has an amplitude greater than the amplitude of the positive component of the second common drive waveform, and / or The positive component of the third common drive waveform has an amplitude greater than the amplitude of the positive component of the fourth common drive waveform, and / or The negative component of the first common drive waveform has an amplitude smaller than the amplitude of the negative component of the second common drive waveform, and / or The circuit according to claim 1, wherein the negative component of the third common drive waveform has an amplitude smaller than the amplitude of the negative component of the fourth common drive waveform.

14. The circuit according to claim 1, wherein the waveform selection unit includes a switching circuit configured to perform a transition from the first common drive waveform to the second common drive waveform.

15. The circuit according to claim 1, wherein the waveform selection unit comprises at least two switching circuits that are controlled by switch control and configured to perform a transition from the first common drive waveform to the second common drive waveform.

16. The circuit according to claim 1, further comprising a timing circuit configured to control the transition from the first common drive waveform to the second common drive waveform.

17. The circuit according to claim 14, wherein the switching circuit further comprises a high-resistance path and a low-resistance path, and the high-resistance path is configured to enable a transition from the first common drive waveform to the second common drive waveform.

18. The circuit according to claim 17, wherein the timing circuit is configured to control the switching of a high-resistance path and a low-resistance path.

19. A droplet dispensing head comprising a plurality of actuators, each actuator associated with at least one fluid chamber, and the circuit described in claim 1.

20. A droplet dispensing device comprising one or more droplet dispensing heads, each having multiple actuators, each actuator associated with at least one fluid chamber, and a circuit for controlling the multiple actuators, wherein the circuit is An input section that receives a first common drive waveform, a second common drive waveform, and a trimming signal, An output unit that supplies individual drive waveforms to actuators, A waveform selection unit configured to couple the first common drive waveform with the output unit for connecting to the first electrode of the actuator, comprising: a waveform selection unit configured to supply the individual drive waveform to one of the actuators selected based on the first common drive waveform, the second common drive waveform, and the trimming signal; A droplet dispensing device wherein the waveform selection unit is further configured to cause a transition from the first common drive waveform to the second common drive waveform by disconnecting the first common drive waveform from the output unit and coupling the second common drive waveform to the output unit, and the transition occurs at a timing determined by the trimming signal.

21. The droplet ejection device according to claim 20, further comprising an ejection signal input unit that receives information designating each actuator as an ejection chamber or a non-ejection chamber for each printing cycle.

22. The fluid chambers to which each actuator is associated are arranged in three groups designated A, B, and C, and any set of three adjacent fluid chambers includes at least one fluid chamber from each of groups A, B, and C. The droplet dispensing device according to claim 20, wherein the fluid chamber is arranged such that actuators belonging to each of the three groups are arranged in the same order to form a repeating pattern, thereby forming the repeating pattern.

23. Each period of length T has three phases, designated as phase A, phase B, and phase C, and chambers with designations that do not match the phase designations are designated as inactive chambers, and only chambers with designations that match the phase designations are assigned as active chambers. The droplet dispensing apparatus according to claim 22, wherein a chamber having a designation matching the phase designation is further assigned as an active dispensing chamber or an active non-dispensing chamber according to the dispensing signal.

24. A common inactive waveform is supplied to the actuator associated with the inactive chamber. A common active-non-discharge waveform is supplied to the actuator associated with the active-non-discharge chamber. The droplet dispensing apparatus according to claim 23, wherein the waveform selection unit is configured to receive a dedicated trimming signal input to each active dispensing chamber, control the transition between the first and second common drive waveforms, and output a dedicated active dispensing waveform to be supplied to the actuator associated with each active dispensing chamber.

25. The droplet dispensing device according to claim 20, wherein the waveform selection unit comprises a switching circuit configured to perform a transition from the first common drive waveform to the second common drive waveform.

26. The droplet dispensing device according to claim 20, wherein the waveform selection unit comprises at least two switching circuits that are controlled by switch control and configured to transition from the first common drive waveform to the second common drive waveform.

27. The droplet dispensing device according to claim 20, further comprising a timing circuit configured to control the transition from the first common drive waveform to the second common drive waveform, wherein the transition occurs at a timing determined by the trimming signal.

28. The droplet dispensing device according to claim 25, wherein the switching circuit further comprises a high-resistance path and a low-resistance path, and the high-resistance path is configured to enable a transition from the first common drive waveform to the second common drive waveform.

29. A method for controlling a plurality of actuators, each of which is associated with at least one fluid chamber in a droplet dispensing device, Receiving the first and second common drive waveforms, Receiving a trimming signal, The first common drive waveform is coupled to the first electrode of the first actuator. In response to the trimming signal, the first common drive waveform is disconnected from the first electrode of the first actuator. A method comprising coupling the second common drive waveform to the first electrode of the first actuator to cause a transition from the first common drive waveform to the second common drive waveform, and the transition occurring at a timing determined by the trimming signal, thereby outputting an individual drive waveform in the printing cycle.

30. Receiving the trimming signal includes receiving a plurality of different trimming signals. The method according to claim 29, wherein each of the plurality of different trimming signals is used to generate different output waveforms for different actuators, and the transitions between the common drive waveforms occur at different timings.

31. The method according to claim 29, wherein a dedicated trimming signal is received for each actuator in order to supply a dedicated individual drive waveform to each actuator, and a transition between the common drive waveforms occurs at a dedicated timing for each actuator.

Images