Monolithic inkjet printhead and ink composition

Abstract

The present disclosure provides a monolithic inkjet printhead for ejecting a set of ink compositions wherein the printhead comprises at least one substrate and the substrate comprises a plurality of ejectors, each comprising: (i) a nozzle; (ii) a chamber for receiving an ink composition in the set, wherein the chamber is in fluid communication with the nozzle; and (iii) a piezoelectric actuator coupled to the nozzles to selectively eject the ink composition from the nozzles, where each ejector is configured to eject ink droplets of the different ink composition at a corresponding volume and velocity. The present disclosure further provides a set of ink compositions that themselves have matched viscosity, density and surface tension values, a printing device, and a method thereof.

Description

Technical Field

[0001] The present invention relates to an integrated inkjet print head, a set of different ink compositions suitable for the print head, a printing device including the print head, and a method thereof. Background Art

[0002] Piezoelectric inkjet (PIJ) printheads remain an area of ​​active research and development. To date, most PIJ printheads incorporate piezoelectric actuators in the walls of the ink chamber. Deformation of the piezoelectric element deflects the piezoelectric actuator, causing a pressure change in the ink stored in the chamber, which causes the ink droplets to be ejected through the nozzle. To achieve the desired printing resolution, commercial PIJ printheads typically employ many parallel electrical connections to external actuator drivers to drive individual piezoelectric actuators within the printhead. The large number of wires not only increases the complexity of manufacturing, but also reduces the reliability of the printing itself. Further, multi-color printing may require different operating inputs (e.g., different actuation waveforms) and / or different nozzles to eject different inks, both of which increase the complexity of the printhead in its operation and configuration.

[0003] As described above, there are one or more problems with the known techniques in the art.

[0004] US2011 / 0134175A1 describes a method for adjusting the inkjet characteristics of an inkjet printing device, the method comprising adjusting at least one of the voltage and application duration of a drive signal applied to a plurality of piezoelectric actuators, the plurality of piezoelectric actuators providing ejection pressure to a plurality of nozzles so that the volumes of a plurality of ink droplets ejected from the plurality of nozzles are uniform; and shifting the application start time of the drive signal applied to the plurality of piezoelectric actuators so that a plurality of droplets ejected from the plurality of nozzles reach a printing medium simultaneously.

[0005] US 6328395B1 describes a drive signal generating device that generates a drive signal including a plurality of drive pulses in one cycle. A print data generating device generates print data to input one or more drive pulses to each pressure generating element during one print cycle. The pressure generating device expands and contracts according to the drive pulses input therein to thereby eject one or more ink droplets.

[0006] US 6364444B1 describes an apparatus for driving an inkjet recording head, the apparatus comprising a piezoelectric device, a drive waveform generating circuit and a waveform extracting circuit. The drive waveform generating circuit generates a drive waveform in which n basic waveforms are connected in series, each of the n basic waveforms having a single cycle. The waveform extracting circuit extracts m of the n basic waveforms as a print drive waveform based on externally supplied print data, and applies the print drive waveform to the piezoelectric device. Thus, based on the deformation of the piezoelectric device, ink is discharged from the nozzle.

[0007] In view of the shortcomings of the prior art, the present invention is intended to provide an improved inkjet printhead and printing device that can reliably perform fine and accurate printing. Embodiments of the present invention seek to provide an inkjet printhead that is simple to manufacture, simple to operate, and compact in configuration. The printhead according to the present invention is used to eject different ink composition sets, such as ink composition sets of different colors.

[0008] The present invention also aims to provide a set of different ink compositions having high quality printing performance characteristics. The ink composition is preferably a set of ink compositions of different colors. The set can be used with an improved inkjet print head having a simple design and simple operation. The ink droplets deposited on the print medium can be given a corresponding size and shape, thereby achieving high quality printing. It should be noted that this does not exclude the use of ink compositions with print heads having a complex design and / or operation (to achieve high quality printing).

[0009] According to the present invention, a set of different ink compositions are used, which, although different, have controlled characteristics so that they can be ejected by corresponding drop ejectors. Desirably, during use, the ink compositions are ejected by substantially the same actuation waveform, and the resulting droplets on the print medium (e.g., a sheet of paper) can have the same size and shape, thereby providing high quality printing while minimizing wiring complexity.

[0010] The present invention further aims to provide a printing device comprising said inkjet print head and preferably said ink composition. In this way, said device can provide all the advantages of the print head and the ink composition.

[0011] WO 2021 / 229040A1 describes a droplet ejector assembly for a print head, the print head comprising a substrate comprising a CMOS control circuit, a plurality of layers on a first surface of the substrate, a fluid chamber having a droplet ejection outlet, and a piezoelectric actuator element formed by one or more of the layers, the piezoelectric actuator element comprising a first electrode and a second electrode in contact with a piezoelectric body.

[0012] US2019 / 0283424A1 describes a droplet ejector for a print head, the droplet ejector comprising a substrate having a mounting surface and a relative nozzle surface; at least one electronic component integrated with the substrate; a nozzle forming layer formed on at least a portion of the nozzle surface; a fluid chamber at least partially defined by the substrate and at least partially by the nozzle forming layer; and a piezoelectric actuator formed on at least a portion of the nozzle portion. Summary of the invention

[0013] In a first aspect of the present invention, there is provided an integrated inkjet print head for ejecting different groups of ink compositions, wherein the print head comprises a substrate, and the substrate comprises a plurality of ejectors, each of the plurality of ejectors comprises: (i) a nozzle; (ii) a chamber for receiving the ink composition in the group, and each of the chambers is fluidically connected to the nozzle; and (iii) a piezoelectric actuator coupled to the nozzle to selectively eject the ink composition from the nozzle.

[0014] Typically, each ejector is configured to eject ink drops of the different ink compositions at corresponding volumes and velocities.

[0015] Typically, each ejector is configured to eject an ink composition that meets multiple physical property criteria at a corresponding volume and velocity, the physical property criteria including at least a corresponding density and viscosity. The physical property criteria typically also include a corresponding surface tension. Typically, a corresponding compressibility factor is not required.

[0016] By corresponding viscosity, it is meant that the viscosity of the ink composition of the composition is the same or similar (e.g., at 25° C. and 1 atmosphere). For example, the viscosity values ​​of the composition may be such that the difference between any two compositions does not exceed 20% of the maximum viscosity value of the group, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1%.

[0017] By corresponding density, it is meant that the densities of the ink compositions are the same or similar (e.g., at 25° C. and 1 atmosphere). For example, the density difference between any two compositions may be no more than 20% of the maximum density value of the group, preferably no more than 10%, more preferably no more than 5%, and most preferably no more than 1%.

[0018] By corresponding surface tension, it is meant that the surface tensions of the ink compositions are the same or similar (e.g., at 25° C. and 1 atmosphere). For example, the surface tension values ​​of the compositions may be such that the difference between any two compositions does not exceed 20% of the maximum surface tension value of the group, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1%.

[0019] It will be understood that all possible combinations of ranges of viscosity, density, surface tension and preferred ranges of viscosity, density, surface tension are also contemplated. For example, the difference in viscosity, density and optionally surface tension between any two compositions may not exceed 10% of the maximum corresponding value of the group, or the difference in viscosity, density and optionally surface tension between any two compositions may not exceed 5% of the maximum corresponding value of the group. It is also possible that the difference in viscosity between any two compositions does not exceed 20% of the maximum viscosity of the group, the difference in density between any two compositions does not exceed 10% of the maximum density of the group, and optionally, the difference in surface tension between any two compositions does not exceed 10% or 5% of the maximum surface tension of the group. It may also be that the difference in viscosity between any two compositions does not exceed 10% of the maximum viscosity of the group, the difference in density between any two compositions does not exceed 5% or 1% of the maximum density of the group, and optionally, the difference in surface tension between any two compositions does not exceed 5% of the maximum surface tension of the group. It may also be that the difference in viscosity between any two compositions does not exceed 1% of the maximum viscosity of the group, the difference in density between any two compositions does not exceed 1% of the maximum density of the group, and optionally, the difference in surface tension between any two compositions does not exceed 1% of the maximum surface tension of the group.

[0020] Typically, the configuration of an injector includes the size of the injector's nozzle and chamber.

[0021] Typically, the configuration of the ejector includes an actuation waveform of the actuator in use. The actuation waveform typically includes a time-varying displacement of the ink composition in the chamber and a force applied to the ink composition during actuation.

[0022] Typically, all nozzles and actuators have corresponding sizes and materials so that the ejected ink drops of the ink composition have corresponding volumes and velocities.

[0023] Typically, the substrate has a first surface and an opposing second surface, the substrate comprising CMOS control circuitry, a plurality of layers on the first surface of the substrate, the piezoelectric actuator being formed from one or more of the layers, and the nozzle comprising a hole through one or more of the layers, such that the piezoelectric actuator displaces one or more of the layers and the nozzle in use to thereby eject the ink composition. Thus, the ejector is typically configured to eject the ink composition in an inertial mode. The hole may extend through the piezoelectric actuator.

[0024] In the context of the present invention, it is typical that the ink droplets of different compositions ejected have corresponding volumes and speeds. The volume and speed can be evaluated by known and effective methods (such as printing test patterns). Various 'printing test patterns' methods have been described in the prior art (such as US2011 / 227988A1, US 8322814B2, US10589519B2 and US7855037B2, incorporated herein by reference). The printing test pattern can be in the form of a printer test page (such as a color printer test page), or configured to allow any suitable form of consistency to be evaluated. The method can optionally be repeated one or more times (for example, when the correspondence of volume and speed needs to be adjusted and should be evaluated again). In other words, printing test patterns can be produced repeatedly. The printing test pattern can include features such as one or more symbols (for example, squares, points, diamonds), numbers, letters, reference points, crosshairs, lines, grids and their mixtures. The positioning of these features can be evaluated (eg, by a user or machine or software or other suitable technique) to determine satisfaction of consistency, since positioning is a function of droplet volume and velocity.

[0025] By corresponding volumes is meant having the same or similar volumes (e.g., at 25° C. and 1 atmosphere). Suitably, the ejected ink droplets have corresponding volumes such that the difference in volume between any two droplets from different ink compositions is no more than 1 picoliter, or no more than 0.5 picoliter, or no more than 0.2 picoliter, or no more than 0.1 picoliter, or no more than 0.05 picoliter, or no more than 0.01 picoliter, or zero. Additionally or alternatively, the difference in volume between any two droplets from different ink compositions relative to the larger volume of the two droplets is no more than 20%, or no more than 10%, or no more than 5%, or no more than 1%, or zero.

[0026] By corresponding speeds, it is meant having the same or similar speeds (e.g., at 25° C. and 1 atmosphere). Suitably, the ejected ink droplets have corresponding speeds such that the speed difference between any two droplets from different ink compositions does not exceed 2 m / s, or does not exceed 1 m / s, or does not exceed 0.2 m / s, or does not exceed 0.1 m / s, or does not exceed 0.05 m / s, or is zero. Additionally or alternatively, the speed difference between any two droplets from different ink compositions does not exceed 20%, or does not exceed 10%, or does not exceed 10%, or does not exceed 5%, or does not exceed 1% or is zero relative to the greater speed of the two droplets. It will be understood herein that all possible combinations of sub-ranges of volume and speed are also contemplated. For example, as described above, the volume difference may not exceed 10%, and the speed difference may not exceed 10% or 5%. For example, as described above, the volume difference may not exceed 5%, and the speed difference may not exceed 5% or 1%. For example, as described above, the volume difference may not exceed 0.5 picoliters, and the velocity difference may not exceed 1 meter per second or 0.2 meter per second. For example, as described above, the volume difference may not exceed 0.2 picoliters, and the velocity difference may not exceed 0.2 meter per second or 0.1 meter per second.

[0027] In the context of the present invention, a printhead is a component used in a printing device. In the present invention, monolithic means that all component parts of the printhead are integrated to form a single unit. This can be achieved by mass-producing multiple ejectors on a single substrate (e.g., from a single substrate wafer) or by manufacturing multiple ejectors on each of multiple substrates and bonding them together.

[0028] The printhead may comprise at least 100 ejectors, preferably at least 1000 ejectors.The printhead may be used to eject a single ink composition from a plurality of nozzles.

[0029] Typically, the printhead comprises a plurality of groups (typically at least four groups) of ejectors, each group of ejectors being used to eject ink compositions, at least two (typically at least four) of the ink compositions being different from one another. In this manner, the exemplary printhead can be used to eject a plurality of (typically at least four) different ink compositions. The groups are typically referred to in the art as channels. Typically, the printhead comprises a separate manifold for each group of ejectors to supply the ink composition to each ejector in the corresponding ejector group from the corresponding ink storage device.

[0030] It will be understood that each ink chamber is in fluid communication with a supply of a corresponding ink composition to a corresponding nozzle. Thus, the chamber not only receives and stores the ink composition, but is also in fluid communication with the nozzle so that the composition is ejected from the nozzle.

[0031] It will be appreciated that the nozzle comprises an opening through which the ink composition can be controllably ejected by operating the piezoelectric actuator. Typically, the cross-sectional area of ​​the nozzle is less than 3 mm 2 , for example, less than 0.3 mm 2 The piezoelectric actuator is typically operated to displace an elastically deformable membrane that defines at least a portion of a nozzle in such a way as to cause the ink composition to be ejected from the nozzle upon operation of the actuator.

[0032] According to the present invention, a piezoelectric actuator is coupled to a corresponding nozzle. Thus, deformation of the piezoelectric actuator during use causes the nozzle to move. Typically, the droplet ejector comprises an elastically deformable membrane, which comprises the piezoelectric actuator and defines at least a portion of the nozzle (or defines the nozzle). Thus, the elastically deformable membrane defines at least a portion (e.g., a wall) of the chamber. Typically, the actuator is arranged adjacent to the nozzle, such as around the nozzle. Typically, actuation of the piezoelectric actuator deflects the elastically deformable membrane that defines the nozzle. Thus, the elastically deformable membrane and the nozzle move during use to eject the ink composition from the chamber through the nozzle. Typically, the print head comprises a nozzle defining layer formed on a substrate, the nozzle defining layer comprising the piezoelectric actuator and defining the nozzle. The nozzle defining layer typically comprises at least one piezoelectric layer and one or more electrodes in electrical contact with the at least one piezoelectric layer.

[0033] This is in contrast to arrangements where the actuator is distally associated with the nozzle and / or the nozzle and actuator are located on different walls of the chamber (e.g., the nozzle is located on one wall of the fluid chamber and the actuator is located on the opposite wall of the same chamber, so that the actuator is far from the nozzle). In existing PIJ technology, the actuator is not coupled to the nozzle / far from the nozzle, and a large actuation force is required to compress almost all of the ink composition stored in the chamber in order to eject the ink composition. Therefore, this operation depends on the compression mode. In these arrangements, the compression coefficient of the ink composition directly affects the printing process. For example, the compression coefficient of the ink composition may affect the ejection process (e.g., by affecting the hardness of the ejector). In this way, the compression coefficient of the ink is also related to the print quality. In addition, the quality of the droplet may be affected by all the ink in the nozzle and the ink in the chamber, and in some configurations, even by the ink very far from the chamber. The complexity of the compression mode is that the remote ink may be associated with the damping of the ejection process. In this way, the damping is moderate, and the ejection process may be susceptible to crosstalk problems, as described below. In contrast, the arrangement of the present invention avoids interfering with most of the ink in the chamber, and only requires a small actuation force to displace the ink in the nozzle. The ink is then ejected from the nozzle primarily by inertial force (i.e., inertial jetting). In this article, the jetting performed by inertial force may also be referred to as inertial jetting or jetting performed by inertial mode. In the context of the present invention, since the actuator is coupled to the corresponding nozzle, the present invention allows the ink to be ejected (from the corresponding nozzle) by inertial mode rather than compression mode. Therefore, for the jetting process, the ink compression coefficient is secondary. The actuator of the present invention is appropriately configured to eject the ink composition (from the corresponding nozzle) by inertial mode (i.e., inertial jetting).

[0034] Jetting by inertial mode (i.e., inertial jetting) has many closely related benefits. It allows the use of low-temperature processable piezoelectric materials (i.e., piezoelectric materials processable at less than 450°C or less than 300°C) with lower piezoelectric constants because only a small actuation force is initially required. The small force applied by the piezoelectric actuator containing the low-temperature processable piezoelectric material gives a relatively low fluid pressure, which reduces the acoustic crosstalk problem (i.e., adjacent actuators and fluid chambers interact through pressure waves in the fluid). The lower level of acoustic crosstalk, in turn, allows close integration of adjacent ejectors to achieve a compact configuration of the printhead. Further, the mass of the droplet may be affected by the ink in the nozzle (e.g., the ink in the nozzle head) rather than by the entire ink volume in the chamber. Therefore, damping is light and crosstalk is reduced, as described above.

[0035] In order to obtain high-quality printing, the ink droplets ejected need to have corresponding volumes and speeds. In this way, the droplets deposited on the print medium (e.g., paper) can give corresponding shapes and volumes. For inertial jetting, it is found that by matching the frequency of the actuation waveform sent to the actuator with the resonant frequency of the corresponding nozzle (e.g., the resonant frequency in use), satisfactory consistency can be achieved. Therefore, the complexity of inertial jetting may be directly related to the number of separate waveforms required to drive the nozzle, especially the nozzles that eject different ink compositions. For simplicity, if all nozzles require the same or similar waveforms (i.e., waveforms with the same or similar frequencies, usually with the same frequency) during actuation, this is typical. If all nozzles have the same or similar resonant frequencies (e.g., the same or similar resonant frequencies during use), this can be achieved. The difference in the resonant frequency of any two nozzles (e.g., in use) can be no more than 10kHz, or no more than 1kHz, or no more than 100Hz, or no more than 10Hz, or no more than 1Hz or zero Hz. The difference in the resonant frequency (e.g., in use) of any two nozzles may be no more than 10%, or no more than 5%, or no more than 1%, or no more than 0.1%, or no more than 0.01%, or zero, relative to the larger resonant frequency of the two nozzles. The waveform frequency may be matched to the resonant frequency (e.g., in use) of the corresponding nozzle so that the difference is no more than 10 kHz, or no more than 1 kHz, or no more than 100 Hz, or no more than 10 Hz, or no more than 1 Hz, or zero Hz. The difference may be no more than 10%, or no more than 5%, or no more than 1%, or no more than 0.1%, or no more than 0.01%, or zero, relative to the resonant frequency (e.g., in use) of the corresponding nozzle. The resonant frequency (e.g., in use) of the nozzle is typically 100000 kHz to 10 kHz, more typically 10000 kHz to 20 kHz, still more typically 5000 kHz to 50 kHz, and most typically 2000 kHz to 100 kHz. The resonant period of the nozzle (eg, in use) is typically 0.01 microseconds (μsec) to 100 microseconds (μsec), more typically 0.1 μsec to 50 μsec, still more typically 0.2 μsec to 20 μsec, and most typically 0.5 μsec to 10 μsec.

[0036] It will be appreciated that the resonant frequency of a nozzle may be affected by the size and material of the nozzle and the corresponding actuator. In order to adjust the resonant frequency as described in the previous paragraph, it is desirable that all nozzles in the printhead have corresponding materials and sizes, and all actuators in the printhead have corresponding materials and sizes. The nozzles may have the same size and material. The actuators may have the same size and material. In this article, size includes the geometry, size and / or configuration of the nozzle and actuator. Material refers to the article (e.g., substance, mixture) used to manufacture the nozzle and actuator.

[0037] It will be further appreciated that the resonant frequency may also be affected by the viscosity and density (and surface tension) of the ink composition in the nozzle. Therefore, it is desirable to adjust these parameters for different ink compositions so that the final resonant frequency of the nozzle is the same or similar (as described above). Thus, a simple actuation force (i.e., the same or similar actuation waveform) can be used to eject ink droplets from the nozzle at a corresponding volume and velocity, thereby producing a high quality print. In other words, it would be beneficial to adjust the identified ink parameters (i.e., viscosity, density, and surface tension) to achieve a high quality print (through a simple operation). This is particularly true for inertial jetting.

[0038] It will be further appreciated that, because the present invention (using inertial jetting) is different from the prior art that relies on compression mode or thermal jetting mode (e.g., thermal inkjet printheads), there is generally no need for adjustment of ink properties such as compressibility (e.g., acoustic compressibility), and / or volatility, and / or heat capacity (Cp), and / or thermal conductivity. In other words, there is generally no need to match one or more of the properties between different ink compositions in the set (e.g., no need to match in the manner described below in the second aspect of the invention).

[0039] In a second aspect of the invention, there is provided a set of different ink compositions for an integrated inkjet printhead according to the first aspect of the invention, wherein: (i) the viscosity values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 20% of the maximum viscosity value of the set, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1%; (ii) the density values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 20% of the maximum density value of the set, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1%; and (iii) the surface tension values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 20% of the maximum surface tension value of the set, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1%. Any two compositions in the set may also have no difference in viscosity value, and / or surface tension value and / or density value. In this context, it will be understood that all possible combinations of ranges of viscosity, density, surface tension and preferred ranges of viscosity, density, surface tension are also contemplated. For example, the difference in viscosity, density and optionally surface tension between any two compositions may not exceed 10% of the maximum corresponding value of the group, or the difference in viscosity, density and optionally surface tension between any two compositions may not exceed 5% of the maximum corresponding value of the group. It is also possible that the difference in viscosity between any two compositions does not exceed 20% of the maximum viscosity of the group, the difference in density between any two compositions does not exceed 10% of the maximum density of the group, and the difference in surface tension between any two compositions does not exceed 10% or 5% of the maximum surface tension of the group. It is also possible that the difference in viscosity between any two compositions does not exceed 10% of the maximum viscosity of the group, the difference in density between any two compositions does not exceed 5% of the maximum density of the group, and optionally, the difference in surface tension between any two compositions does not exceed 5% or 1% of the maximum surface tension of the group.

[0040] As described above, the ink composition set is formulated so that the selected properties of the composition (viscosity, density and surface tension) are specifically matched. In this way, the set can provide high quality printing (through simple operation). In particular, in inertial jetting, the same or similar actuation waveforms can be used to jet these matched inks to give corresponding volumes and velocities, which results in corresponding shapes and volumes of ink drops deposited on the print medium.

[0041] As mentioned above, it is generally not necessary to match the compressibility of the ink compositions. As used herein, compressibility (k) refers to the fractional change in volume per unit increase in pressure, typically measured at 20°C (and 1 atmosphere). Compressibility (k) is also known as the reciprocal of bulk modulus (B). For example, for every increase in pressure of one atmosphere, the volume of water will decrease by 46.4 parts per million (i.e., k = 46.4).

[0042] In the context of the present invention, the difference in the compressibility (k) of two ink compositions in the set, or any two ink compositions in the set, may be at least 1% or at least 5% of the maximum compressibility value of the set, or at least 10%, or at least 20%, or at least 30%, or at least 40% or at least 50% of the maximum compressibility value of the set.

[0043] In some embodiments, the difference in viscosity between any two compositions does not exceed 1% of the maximum viscosity of the set, the difference in density between any two compositions does not exceed 1% of the maximum density of the set, and optionally, the difference in surface tension between any two compositions does not exceed 1% of the maximum surface tension of the set, and the difference in compressibility (k) between two ink compositions in the set or any two ink compositions in the set is at least 1%.

[0044] In the context of the present invention, the viscosity values, density values ​​and surface tension values ​​of the different ink composition sets can be matched in such a way that the ink drops ejected from the integrated inkjet printhead have corresponding volumes and velocities. The 'printing test pattern' method as described herein can be used to assess whether the drops correspond.

[0045] The viscosity, density, surface tension of the group can be matched according to the combination of the above two paragraphs. In this article, 'different ink compositions' refer to ink compositions containing one or more components that are different from each other and / or having one or more weight percentages that are different from each other. The weight percentage can be the weight percentage of the same or different components contained in the composition, and all mentioned weight percentages are based on the total weight of the corresponding ink composition. For example, the group can include a first composition containing 80% aqueous carrier, and a second composition containing 80% organic carrier; or the composition can include a first composition containing 80% aqueous carrier, and a second composition containing 85% aqueous carrier. At least two compositions in the group are different from each other, and any two compositions in the group can be different from each other.

[0046] In the context of the present invention, the viscosity values ​​of the compositions may be matched in such a way that the difference between any two compositions does not exceed 4 mPa·s, or does not exceed 2 mPa·s, or does not exceed 1 mPa·s, or does not exceed 0.2 mPa·s, or is zero. The density values ​​of the compositions may be matched in such a way that the difference between any two compositions does not exceed 200 kg / m 3 , or not more than 100kg / m 3 , or not more than 50kg / m 3 , or not more than 10kg / m 3 , or not more than 1kg / m 3 The surface tension values ​​of the compositions may be matched in such a way that the difference between any two compositions does not exceed 7 mN / m, or does not exceed 5 mN / m, or does not exceed 2 mN / m, or does not exceed 1 mN / m or is zero.

[0047] The viscosity of the composition may be 1.5 mPa·s to 20 mPa·s, or 5 mPa·s to 15 mPa·s, or 7.5 mPa·s to 12.5 mPa·s. The density of the composition may be 650 kg / m 3 Up to 1750kg / m 3 , or 800kg / m 3 Up to 1500kg / m 3 or 1000kg / m 3 Up to 1250kg / m 3 . The surface tension value of the composition can be 20mN / m to 75mN / m, or 25mN / m to 70mN / m, or 30N / m to 65N / m, or 35mN / m to 60mN / m or 40mN / m to 55mN / m. It will be understood that the viscosity values, density values ​​and surface tension values ​​of different ink compositions are appropriately matched as described herein (i.e., any possible combination is also considered), and optionally, these values ​​can also be within the numerical range as described herein (i.e., any possible combination is also considered). For example, the viscosity difference can be no more than 4mPa·s, and the density difference can be no more than 50kg / m 3 , the surface tension difference does not exceed 5 mN / m, and optionally, the viscosity value is 5 mPa·s to 15 mPa·s, and the density value is 800 kg / m 3 Up to 1500kg / m 3 , and the surface tension value is 30N / m to 65N / m (e.g., 35mN / m to 60mN / m or 40mN / m to 55mN / m).

[0048] Suitable viscosity test methods can be based on or derived from ASTM D 4040-99. Suitably, the viscosity mentioned in the present invention is measured at 25°C / 1 atmosphere by using a rotational viscometer (RE-80L, manufactured by TOKI SANGYO CO., LTD.). A standard conical rotor (1°34'×R24) geometry can be used, and the ink sample size is about 1.2 mL. The rotation speed of the geometry is 50 revolutions per minute (rpm). The measurement lasts for three minutes. The viscosity value is recorded at the end of the three-minute measurement. Typically, one ink sample requires three repetitions, and the viscosity value reported is the average of these three measurements.

[0049] Suitable density test methods can be based on or derived from ASTM D1475-98. Suitably, the density mentioned in the present invention is measured at 25°C / 1 atmosphere by using a clean and dry measuring cylinder (e.g., 100mL or 250mL). A balance is used to measure the mass (M) of the cylinder (e.g., usually in grams). The cylinder is then removed from the balance and filled with the ink sample. The volume (V) of the ink sample is recorded. The filled cylinder is placed back on the balance and the new mass is recorded. The density of the ink sample is determined by the following equation:

[0050] D 密度 =(M 圆筒+油墨 -M 圆筒 ) / V 油墨

[0051] Typically, three replicates are required for one ink sample, and the density value reported is the average of these three measurements.

[0052] Suitable surface tension test methods can be based on or derived from ASTM D1331-20. Suitably, the surface tension mentioned in the present invention is measured at 25°C / 1 atmosphere by using a Kruss tensiometer (e.g., Kruss K11, K100). A ring method (i.e., the probe is a ring) can be used. Typically, before each ink measurement, the tensiometer is calibrated by water (e.g., surface tension = 72mN / m). A suitable amount of ink sample (e.g., 2mL-5mL) is placed in a sample container equilibrated at 25°C. The experimental procedure for obtaining surface tension values ​​generally follows the steps described in the supplier's manual. These steps generally include lowering the ring to contact the ink surface, waiting for equilibrium, lifting the ring from the ink surface, and recording the surface tension value measured during the lifting process. Typically, one ink sample requires three repetitions, and the reported surface tension value is the average of these three measurements.

[0053] In the context of the present invention, different ink composition sets may have the following chemical characteristics.

[0054] Colorants

[0055] Different ink composition groups may include multiple ink compositions, each of which includes different colorants (i.e., any two compositions in the group include colorants that are different from each other). Typically, the colorant is selected from cyan (C), yellow (Y), magenta (M), black (K), red (R), green (G), blue (B), orange, purple, gold, silver, white, and mixtures thereof, more preferably selected from CYMK and mixtures thereof, or selected from RGBK and mixtures thereof. The different ink composition groups may include a first composition including a cyan (C) or red (R) colorant, a second composition including a yellow (Y) or green (G) colorant, a third composition including a magenta (M) or blue (B) colorant, and a fourth composition including a black (K) colorant. Preferably, the first composition includes a cyan (C) colorant, the second composition includes a yellow (Y) colorant, the third composition includes a magenta (M) colorant, and the fourth composition includes a black (K) colorant.

[0056] In a suitable example, the printhead comprises four groups of ejectors (channels), wherein each of the four groups of ejectors comprises a plurality of nozzles (e.g., 100 or 1000), and each group is operably connected to or coupled to a colored ink composition as described above to allow the composition to be ejected from a plurality of nozzles. In the same example, each of the four ink compositions may comprise a different colorant. Preferably, the four ink compositions have CMYK or RGBK colorants, more preferably CMYK colorants.

[0057] Coloring agent can be pigment, dye or lake (that is, the dye that is precipitated into solid form from solvent), usually pigment or dye.Pigment can be inorganic pigment, organic pigment, pearlescent pigment, metallic pigment or its mixture.Inorganic pigment can be selected from titanium oxide, zinc oxide, zinc sulfate, iron oxide, calcium oxide, antimony oxide, magnesium oxide, zirconium oxide, CI. Pigment White 6,18 and 21, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, carbon black (for example, acetylene black, channel black, furnace black, lamp black, thermal black (thermal black)) and its mixture.These pigments can be produced by known effective method (such as contact method, furnace method and thermal method). Organic pigments can be selected from azo pigments (e.g., insoluble azo pigments, condensed azo pigments, chelated azo pigments), polycyclic pigments (e.g., phthalocyanine pigments, diarylide pigments, xanthene pigments, perylene pigments, cyclic ketone pigments, anthraquinone pigments, anthrapyridone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments and quinophthalone pigments), dye chelates, nitro pigments, nitroso pigments, aniline black, white hollow resins and mixtures thereof. Pearlescent pigments can be selected from titanium dioxide-coated mica, fish scale foil, bismuth trichloride and mixtures thereof. Metallic pigments are usually simple or mixed metals selected from aluminum, silver, gold, platinum, nickel, chromium, tin, zinc, indium, titanium, copper and alloys thereof. Dyes can be selected from acid dyes, direct dyes, reactive dyes, basic dyes, food dyes and mixtures thereof. Examples of dyes include CI Acid Yellow 17, 23, 42, 44, 79 and 142, CI Acid Red 52, 80, 82, 249, 254 and 289, Disperse Red 60, CI Acid Blue 9, 45 and 249, CI Acid Black 1, 2, 24 and 94; CI Food Black 1 and 2, CI Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144 and 173, CI Direct Red 1, 4, 9, 80, 81, 225 and 227, CI Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199 and 202, CI Direct Black 19, 38, 51, 71, 154, 168, 171 and 195, CI Reactive Red 14, 32, 55, 79 and 249 and CI Reactive Black 3, 4 and 35. The total level of colorant is suitably 0.01 wt% to 10 wt%, or 0.1 wt% to 8 wt%, or 0.5 wt% to 5 wt% or 1 wt% to 3 wt% of the total ink composition. Typically, the difference in the weight percentage of total colorant contained in at least two compositions in the group or any two compositions in the group does not exceed 5, or does not exceed 2, or does not exceed 1, or does not exceed 0.1 or is zero.Herein, the difference in weight percentage of total colorant contained in at least two compositions in the group or any two compositions in the group may also be at least 0.01, or at least 0.1, or at least 1, or at least 2, or at least 5.

[0058] Typically, the different ink composition groups include a first composition comprising a cyan (C) or red (R) colorant, a second composition comprising a yellow (Y) or green (G) colorant, a third composition comprising a magenta (M) or blue (B) colorant, and a fourth composition comprising a black (K) colorant, wherein each of the colorants is present at 1% to 10% (e.g., 1% to 5% or 1% to 3%) by weight of the respective composition. Optionally, the difference in the weight percentages of these colorants contained in at least two compositions or any two compositions is no more than 2, or no more than 1, or no more than 0.1 or zero. For example, the first composition may contain 2 wt% of a cyan colorant, the second composition may contain 2.5 wt% of a yellow colorant, the third composition may contain 3 wt% of a magenta colorant, and the fourth composition may contain 4 wt% of a black colorant. Optionally, the difference in the weight percentages of the colorants contained in at least two compositions in the group or any two compositions in the group is at least 0.01, or at least 0.1, or at least 0.5, or at least 1 or at least 2. For example, the first composition may include 1 wt % of a cyan colorant, the second composition may include 3 wt % of a yellow colorant, the third composition may include 5 wt % of a magenta colorant, and the fourth composition may include 7 wt % of a black colorant.

[0059] In the context of the present invention, one or more components (excluding the colorant present) of at least two or any two colored ink compositions may be different. Additionally or alternatively, the weight percentages of one or more components (excluding the colorant present) of at least two or any two colored ink compositions may also be different.

[0060] At least one ink composition of the group or each ink composition of the group may further comprise one or more components selected from carriers, rheology modifiers, surfactants, dispersants, defoamers, corrosion inhibitors, UV curable resins, preservatives and wetting agents, or selected from carriers, rheology modifiers, surfactants and wetting agents, or selected from carriers, rheology modifiers and surfactants, or selected from rheology modifiers. At least one ink composition of the group or each ink composition of the group may comprise a carrier, and / or a rheology modifier and / or a surfactant. At least one ink composition or each ink composition may comprise a carrier, a rheology modifier and a surfactant.

[0061] Rheology Modifiers

[0062] At least one ink composition in the group or each ink composition in the group may include a rheology modifier. The modifier helps to modify (e.g., adjust) the rheological behavior (e.g., viscosity) of the ink composition. In this way, if the viscosity values ​​are not matched within the group, the rheology modifier can increase or decrease the viscosity (where appropriate) to help match. Although not required, it is desirable that at least two compositions in the group or all compositions have the same rheology modifier. It is also possible that at least two compositions in the group or any two compositions in the group have rheology modifiers that are different from each other. Those skilled in the art can effectively adjust the type and / or level of modifiers included in the composition. Typically, the total level of rheology modifiers is 0.1 wt % to 25 wt %, or 1 wt % to 20 wt %, or 2 wt % to 15 wt % or 5 wt % to 10 wt % based on the weight of the total ink composition. Typically, the difference in the weight percentage of the total rheology modifiers included in at least two compositions in the group or any two compositions in the group does not exceed 10, or does not exceed 5, or does not exceed 1 or does not exceed 0.1. For example, the first composition may contain 20 wt% of the modifier, the second composition may contain 10 wt% of the modifier, and the third composition may contain 15 wt% of the modifier. It is also possible that at least two compositions in the group (e.g., all compositions in the group) contain the same level of rheology modifier. The difference in weight percentage of the total rheology modifier contained in at least two compositions in the group (e.g., any two compositions in the group) may also be at least 0.01, or at least 0.1, or at least 1, or at least 2, or at least 5, or at least 10. For example, the first composition may contain 20 wt% of the modifier, the second composition may contain 25 wt% of the modifier, and the third composition may contain 15 wt% of the modifier.

[0063] Suitable examples of rheology modifiers are polymers. Polymers can be natural or synthetic. Additionally and optionally, rheology modifiers can be selected from anionic polymers, nonionic polymers or amphoteric polymers. Typically, polymers are polyurethanes, polyacrylic acids or polyacrylates, polysaccharides (e.g., cellulose, mannose, fructose, galactose, glucose, mannose, ribose, xylose, arabinose, gum, guar gum, pectin, starch), polyvinyl alcohol or ethoxylated polymers. Preferred selections are polyacrylic acids or polyacrylate homopolymers or copolymers. Such polymers can be prepared by addition polymerization of ethylenically unsaturated monomer mixtures. Polyacrylic acids or polyacrylates can also be linear or crosslinked copolymers, and such copolymers can optionally be hydrophobically modified. Typically, the ink composition (e.g., at least one ink composition in the set or all ink compositions in the set) comprises a rheology modifier, which is a polymer (e.g., a polyacrylic acid or polyacrylate as described herein), at a level of 0.1 wt% to 5 wt%, or 0.2 wt% to 2 wt%, or 0.5 wt% to 1 wt% of the total composition.

[0064] Commercial examples of polymeric rheology modifiers include, but are not limited to RM-5000 and RM-825 (Rohm & Haas, a wholly owned subsidiary of The Dow Chemical Company); L75N, L0625 and L W44 (all available from OMG Borchers GmbH, Langenfield, Germany), 428 and 429 (both available from BYK Chemie GmbH); and R2000 E. R3000 E and R3075 E (both available from Cognis GmbH, Monheimam Rhein, Germany).

[0065] Another suitable example of a rheology modifier is glycerol. Other polyols may also be used. It has been found that glycerol can effectively increase the viscosity of the ink composition, contributing to the matching of viscosity values. Typically, the ink composition (e.g., at least one ink composition in the group or all ink compositions in the group) comprises 5 wt % to 25 wt %, or 7 wt % to 20 wt %, or 10 wt % to 15 wt % of glycerol in the total composition. One or more compositions in the group (e.g., all compositions in the group) may comprise glycerol, or both glycerol and a polymer rheology modifier, optionally in a glycerol / polymer ratio of 100 / 1 to 1 / 1, or 50 / 1 to 2 / 1, or 20 / 1 to 5 / 1, or 15 / 1 to 10 / 1. One or more compositions in the group may also comprise glycerol, and one or more compositions comprise a polymer rheology modifier.

[0066] Carrier

[0067] One or more ink compositions (e.g., all ink compositions) in the set may include a carrier. The carrier is typically a liquid at 20° C. at atmospheric pressure. In this context, a carrier refers to a liquid in which other components of the ink composition can be dispersed or dissolved to form the composition.

[0068] The ink composition may suitably include one or more carriers. The ink composition may be water-based or oil-based. Therefore, the carrier may be an aqueous carrier, an organic carrier, or a mixture thereof. Advantageously, at least two compositions in the group or all compositions in the group include the same carrier, or include at least the same type of carrier (e.g., all compositions include an aqueous carrier, or include an organic carrier, or include a mixture of an aqueous and an organic carrier). In this way, the density of the group can be easily matched. At least two compositions in the group or any two compositions in the group may also include different carriers, or include different types of carriers (e.g., one of the at least two ink compositions includes an aqueous carrier, and the other of the at least two ink compositions includes an organic carrier).

[0069] Herein, aqueous carrier generally refers to a water-containing carrier, generally accounting for at least 50% by weight of water, or at least 70wt%, or at least 80wt%, or at least 90wt%, or at least 95wt% or 100wt% of the total aqueous carrier. The aqueous carrier can be water. Generally, the water is purified water. Examples of purified water include, but are not limited to, deionized water (DI water), ultrafiltered water, distilled water, and ion exchanged water. Using such water can prevent the growth of microorganisms (e.g., fungi, molds) during ink storage, thereby promoting ink hygiene.

[0070] The carrier may be an oil. In this context, the term 'oil' refers to a water-insoluble organic material that is liquid at 20°C. Any material having a solubility of less than 0.1 g / 100 Ml at 20°C is considered insoluble. The oil may be selected from hydrocarbons (e.g., aliphatic hydrocarbons, isomerized aliphatic hydrocarbons, branched or linear aliphatic hydrocarbons, aromatic hydrocarbons), silicone oils, vegetable oils, and mixtures thereof. An oil carrier is an organic carrier.

[0071] The carrier can also be a water-soluble or water-miscible organic carrier. Suitable examples include, but are not limited to, ethanol, isopropanol, acetone, diacetone alcohol, polyols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, propylene glycol, butylene glycol), glycol ethers (e.g., ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether), amines with hydroxyl groups, and mixtures thereof.

[0072] Other suitable examples of carriers include, but are not limited to, triethylene glycol monobutyl ether, 2-[2-(2-butoxyethoxy)ethoxy]ethanol, 3-methyl-1,5-pentanediol, poly(oxy-1,2-ethanediyl), α,α'-[1,4-dimethyl-1,4-bis(2-methylpropyl)-2-butyne 1,4-diyl]bis[ω.-hydroxy], bis(2-ethoxyethyl) ether, and 1-ethoxy-2-(2-methoxyethoxy)ethane.

[0073] The total level of carrier in the ink composition is typically 10 wt % to 85 wt %, or 15 wt % to 80 wt %, or 20 wt % to 75 wt %, or 50 wt % to 70 wt % of the total composition. If the carrier is an aqueous carrier (e.g., water), the total level in the ink composition is typically 50 wt % to 85 wt %, or 55 wt % to 80 wt %, or 60 wt % to 70 wt %. If the carrier is an organic carrier (e.g., oil, water-soluble organic carrier) or a mixture of organic carriers, the total level is typically 10 wt % to 60 wt %, or 20 wt % to 50 wt %, or 30 wt % to 40 wt %. If the carrier is a mixture of an aqueous carrier and an organic carrier, the weight ratio of the aqueous carrier to the organic carrier may be at least 1 / 1 or greater than 1 / 1. Typically, the difference in the weight percentage of carrier contained in any two compositions in the group or at least two compositions in the group does not exceed 10, or does not exceed 5, or does not exceed 1, or does not exceed 0.1. All compositions in the group may also contain the same level of carrier. For example, the set may contain five different ink compositions, and each ink composition contains a total of 80 wt% of carrier. The difference in weight percentage of carrier contained in at least two compositions in the set (e.g., any two compositions in the set) may also be at least 0.01, or at least 0.1, or at least 1, or at least 5, or at least 10.

[0074] Surfactants

[0075] At least one ink composition or each ink composition in the group may include a surfactant. Surfactants are generally used to reduce the surface tension of the ink composition. In this way, the surfactant helps to adjust (if necessary) the surface tension of the ink composition. The surfactant may be selected from anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants and mixtures thereof. It is desirable that any at least two compositions in the group or any two compositions in the group include the same surfactant, or include at least the same type of surfactant (that is, all compositions include anionic surfactants, or include cationic surfactants, or include nonionic surfactants, or include amphoteric surfactants). At least two compositions in the group or any two compositions in the group may also include surfactants different from each other, or include different types of surfactants (for example, one of the at least two ink compositions includes anionic surfactants, and the other of the at least two ink compositions includes nonionic surfactants).

[0076] Typical examples of surfactants include, but are not limited to, acetylenic surfactants, phosphate ester surfactants (e.g., phosphate esters of fatty alcohols or fatty alcohol alkoxylates), acetylene glycol-based surfactants, silicone-based surfactants (e.g., polysiloxanes), polyethylene glycol (PEG)-based surfactants (e.g., PEG 8000, polysorbate 80, Pluronic F-68, PEG fatty acids), fluorine-based surfactants (e.g., fluorine-modified polymers), and mixtures thereof.

[0077] The total level of surfactant is typically 0.01 wt % to 10 wt %, or 0.02 wt % to 2.5 wt %, or 0.05 wt % to 2 wt %, or 0.1 wt % to 1 wt % of the ink composition. Typically, the difference in weight percent of surfactant contained in at least two compositions in the group or any two compositions in the group is no more than 5, or no more than 2, or no more than 1, or no more than 0.1. All compositions in the group may also contain the same level of surfactant. For example, a group may contain five different ink compositions, and each composition contains the same level of surfactant in total. The difference in weight percent of surfactant contained in at least two compositions (e.g., any two compositions in the group) may also be at least 0.01, or at least 0.1, or at least 1, or at least 2, or at least 5.

[0078] Wetting Agents

[0079] At least one or each of the ink compositions in the set may include a wetting agent. A wetting agent is typically a water-soluble or water-miscible organic compound. Inclusion of such a compound may improve the moisture retention of the ink composition, making it less likely that the nozzle will become clogged even if left unattended for long periods of time.

[0080] Typically, the wetting agent comprises a hydrophilic group. The wetting agent can be selected from alkyl polyols (e.g., ethylene glycol, propylene glycol, glycerol), nitrogen-containing cyclic compounds (e.g., 2-pyrrolidone, N-methyl-2-pyrrolidone), lactones (e.g., γ-butyrolactone), betaines, glycol ethers (e.g., diethylene glycol monobutyl ether, propylene glycol monoethyl ether), ureas (e.g., ethyl urea, tetramethyl urea, thiourea, 1,3-dimethyl-2-imidazolidinone), amides (e.g., N-methylformamide), amines (e.g., monoethanolamine, triethylamine) and mixtures thereof.

[0081] The total level of wetting agent is generally 0.1 wt% to 30 wt%, or 0.2 wt% to 20 wt%, or 0.5 wt% to 15 wt%, or 1 wt% to 10 wt%, or 2 wt% to 5 wt% of the total ink composition. The amount included is effective to prevent clogging, and it is possible for a skilled worker to match the viscosity, density, and surface tension values ​​of the set.

[0082] Other optional components

[0083] Further, at least one ink composition in the group or each ink composition in the group may include a preservative. Examples may include sodium benzoate, sodium pentachlorophenol, phenoxyethanol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-benzisothiazolin-3-one and 4-chloro-3-methylphenol. The ink composition may include a UV-curable resin (e.g., acrylated epoxy resin, acrylated polyester, acrylated polyurethane, acrylated silicone). The ink composition may include a dispersant. Examples of dispersants may include anionic dispersants (e.g., sodium naphthalenesulfonate), nonionic dispersants, polymer dispersants (e.g., acrylic resins, styrene resins, polyurethane resins). The composition may include a defoamer, such as a silicone-based defoamer, a polyether-based defoamer, a fatty acid ester-based defoamer. The composition may include a corrosion inhibitor, such as an acidic sulfite and sodium thiosulfate. Each of the above optional components may be present in an amount that effectively achieves its purpose in the ink composition. Typically, each of these optional components is present in an amount of up to 5% by weight of the total ink composition.At least one of the ink compositions in the set or each composition in the set may contain one or more optional components as described herein.

[0084] In a preferred embodiment, at least one composition in the group or each composition in the group comprises a colorant (e.g., 0.01-10 wt %), a carrier (e.g., 10-85 wt %), a surfactant (e.g., 0.01-5 wt %), and a rheology modifier (e.g., 0.1-25 wt %). The composition may also comprise one or more other ingredients as described herein (e.g., optionally 0.1 wt % to 10 wt % of a wetting agent). In a still preferred embodiment, the different ink composition groups include a first composition comprising a cyan (C) or red (R) colorant, a second composition comprising a yellow (Y) or green (G) colorant, a third composition comprising a magenta (M) or blue (B) colorant, and a fourth composition comprising a black (K) colorant (e.g., a black colorant), wherein each of the colorants is present at 1% to 10% by weight of the respective composition. In the same or other embodiments, at least one composition in the group or each composition in the group may further include a carrier (e.g., 10-85wt% or 50-80wt%), a surfactant (e.g., 0.01-5wt% or 0.1-2wt%), and a rheology modifier (e.g., 0.1-25wt% or 0.5-20wt%).

[0085] In the above preferred embodiments and other embodiments, the difference in weight percentage of the colorant contained in at least two compositions or any two compositions in the group may be no more than 5, or no more than 2, or no more than 1 or no more than 0.1, and any weight percentage is based on the total weight of the corresponding ink composition. The difference in weight percentage of the total colorant contained in at least two compositions in the group (e.g., any two compositions in the group) may also be at least 0.01, or at least 0.1, or at least 1, or at least 2 or at least 5. Alternatively or additionally, the difference in weight percentage of the rheology modifier, and / or surfactant and / or carrier contained in at least two compositions or any two compositions may be no more than 20, or no more than 10, or no more than 5, or no more than 1 or no more than 0.1. Alternatively or additionally, at least two compositions in the group or any two compositions in the group may contain rheology modifiers that are different from each other, and / or surfactants that are different from each other and / or carriers that are different from each other, and optionally, the difference in weight percentage of the rheology modifier, and / or the surfactant and / or the carrier contained in at least two compositions in the group (e.g., any two compositions in the group) is at least 0.1, or at least 1, or at least 5 or at least 10.

[0086] Method for producing ink composition

[0087] In another aspect of the present invention, a method for preparing a set of different ink compositions as described herein is provided. The method comprises the following steps: (i) preparing at least two ink compositions; (ii) determining whether the viscosity values, density values ​​and surface tension values ​​of the at least two ink compositions match in the manner as described herein (i.e. the set is a set of different ink compositions according to the present invention); and (iii) if this is not the case, modifying at least one of the at least two ink compositions one or more times until the set of compositions is a set according to the present invention. The set of different ink compositions is used in a printing device as described below.

[0088] The method may further comprise the steps of: (a) mixing the carrier, colorant, rheology modifier, surfactant, and optionally other components (eg, as described herein), and optionally (b) filtering to remove one or more impurities from the mixture.

[0089] Steps (a) and / or (b) may optionally be repeated.

[0090] In step (a), mixing can be performed in any suitable order. It is usually performed by adding the required components to a container equipped with a stirrer (e.g., a magnetic stirrer, a sand mill, a homogenizer, a ball mill), and mixing the components in the container until uniform. Mixing can also be performed by using a paint shaker or an ultrasonic dispersing device or any suitable high-speed dispersing device.

[0091] The viscosity values, density values, and surface tension values ​​of the ink compositions can be determined by any suitable method (e.g., by ASTM methods or suitable methods described herein). Virtual simulations (e.g., computer calculations for predicting those values ​​for the inks) are not excluded. If these values ​​match as described herein (i.e., the ink composition sets are different ink composition sets according to the present invention), further modification of the inks may not be necessary.

[0092] If these values ​​do not match as described herein, the viscosity, density and surface tension can be appropriately changed (e.g., adjusted), for example, by adjusting the type and / or level of the rheology modifier, carrier and surfactant, respectively. The modified (e.g., adjusted) ink composition can be determined for its viscosity, density and surface tension. If necessary, further modifications (e.g., adjustments) can be performed to achieve matching as described herein. In other words, steps (ii) and (iii) of the method can optionally be repeated until matching is achieved (i.e., until the composition set is a set according to the present invention).

[0093] The obtained different ink composition sets can be used for printing. The obtained different ink composition sets can be used as specifications for the inks to be manufactured. The corresponding inks can then be manufactured.

[0094] Selecting ink composition set

[0095] In yet another aspect of the present invention, there is provided a method for selecting different ink composition sets, the method comprising the steps of: (i) defining at least one characteristic of the ejected ink droplets; (ii) using the at least one defined characteristic to determine target values ​​for viscosity, density and surface tension of the ink composition; and (iii) selecting at least two ink compositions with reference to the target values ​​as described in step (ii), wherein the values ​​of the at least two ink compositions are also matched in the manner as described herein (i.e., the ink composition sets are different ink composition sets according to the present invention). The different ink composition sets are used in a printing device as described below.

[0096] The at least one defined characteristic may be used to determine target values ​​for viscosity, density and surface tension of an ink composition in combination with a printhead according to the present invention or a simulation thereof.

[0097] At least one defined characteristic of the jetted ink droplets may include the size of the droplets. Additionally and optionally, in step (i), a value of dots per inch (DPI) may also be defined. The DPI may be 100 to 2000 dpi, or 300 to 1800 dpi, or 600 to 1600 dpi. The defined characteristics of the ink droplets (optionally with a defined DPI) help determine the target physical properties (i.e., viscosity, density, and surface tension) of the ink. It will be further understood that the characteristics of the jetted droplets and / or DPI may be virtually defined (e.g., by using a computer-implemented method). The ink composition is selected with reference to these target physical properties. In this article, 'reference' means that the physical properties of the selected ink match the target physical properties. Typically, the viscosity difference does not exceed 10%, or does not exceed 5%, or does not exceed 1%, relative to the target viscosity. Typically, the density difference does not exceed 20%, or does not exceed 10%, or does not exceed 5%, or does not exceed 1%, relative to the target density. Typically, the surface tension difference does not exceed 10%, or does not exceed 5%, or does not exceed 1%, relative to the target surface tension. Any possible combination of sub-ranges is also contemplated. As described herein, the selected inks also have physical properties that match one another (ie, the selected ink composition sets are different ink composition sets according to the present invention).

[0098] After determining the target physical property (i.e., after step (ii)), a set of candidate ink compositions may first be determined. Typically, the candidate ink compositions are already different from each other (due to differences in color or chemical composition or reactivity). The viscosity, surface tension, and density of the candidates may be determined (e.g., according to methods as described herein). If these values ​​match each other (as described herein) and match the target physical property, the candidate set may be selected (e.g., according to step (iii)). Otherwise, at least one composition in the set may be modified (e.g., one or more times, optionally by methods as described herein), and the physical properties of the modified set may be determined again. The modification and determination may optionally be repeated until the desired match is achieved. The modified different ink set may then be selected for subsequent manufacture and / or use (e.g., according to step (iii)).

[0099] printer

[0100] In yet another aspect of the present invention, a printing device is provided, comprising an integrated print head according to the first aspect of the present invention. The printing device further comprises a signal generator, the signal generator being configured to generate a drive signal having a repetitive waveform; and a control circuit system, the control circuit system being configured to relay the drive signal to the actuator through a switch and control the switch to selectively apply the drive signal to individual actuators to thereby eject ink droplets of the different ink compositions at corresponding volumes and speeds. Preferably, the printing device is a printer. Preferably, the printing device comprises different ink composition sets of the present invention, and the ink compositions are received or can be received in a chamber of the print head. Preferably, the viscosity, density and surface tension of the different ink composition sets are matched in such a way that the difference between any two compositions does not exceed 5% (or does not exceed 1%) of the maximum corresponding value of the set. Optionally and additionally, the difference in the compressibility of the two ink compositions or any two ink compositions is at least 5% (or at least 10%) of the maximum compressibility value of the set.

[0101] The printhead and the set of different ink compositions may be contained in an ink cartridge, wherein the compositions are received in chambers of the printhead.The ink cartridge may be an integral part of a printing device.

[0102] Suitably, the control circuitry configured to relay the drive signals is contained in the integral inkjet printhead. In other words, the control circuitry may be part of the printhead. Furthermore, the complexity of the wiring connections in the printhead may be reduced, as only separate control wiring to each actuator needs to be provided from the control circuitry on each printhead; control instructions for any actuator on the printhead may be provided to the printhead via a single wiring connection to the control circuitry on the printhead.

[0103] The control circuitry may include CMOS circuitry (ie, complementary metal oxide semiconductor) and a plurality of circuit elements, each circuit element being associated with a print head ejector.

[0104] The control circuitry may be formed integrally with the print head nozzles. In other words, the control circuitry, the print head nozzles and (optionally) the formation of the piezoelectric actuator may be provided simultaneously without the need to assemble a plurality of component parts separately. By providing the control circuitry using an integrated circuit, the control circuitry may be provided adjacent to the print head nozzles, thereby ensuring that the print head is compact.

[0105] The control circuit system may include (a) digital registers. The control circuit system may include (b) nozzle fine-tuning calculation circuits and / or registers. The control circuit system may include (c) temperature measurement circuits. The control circuit system may include (d) fluid chamber fill detection circuits.

[0106] The digital register may be, for example, a shift register or a latch register. In operation, data may be stored in or read from the register within the control circuit system. In operation, the temperature may be measured using a temperature sensitive component of the temperature measurement circuit. In operation, the fill level of the fluid chamber may be measured.

[0107] The control circuitry may be configured to modify the voltage pulses applied to the one or more electrodes of the one or more piezoelectric actuators in response to data stored by the control circuitry or measurements from one or more sensors, typically within the printhead. In operation, the control circuitry may measure the voltage pulses applied to the one or more electrodes of the one or more piezoelectric actuators in response to data stored by the control circuitry or measurements from one or more sensors, typically within the printhead.

[0108] Modifying the voltage pulse may include shifting it in time. Modifying the voltage pulse may include compressing or expanding it. Modifying the voltage pulse may include modifying its magnitude. Modifying the voltage pulse may include switching between multiple (usually repeating) sequences of received actuator drive pulses having different characteristic curves. The control circuit system is typically configured to modify the voltage pulses applied to one or more electrodes of one or more individual piezoelectric actuators in response to data stored by the control circuit system related to the individual piezoelectric actuators or measurements from one or more sensors.

[0109] The control circuit system includes a plurality of circuit elements, each circuit element being associated with a print head ejector. The circuit element may be an ejection transistor. The ejection transistor is typically in direct electrical communication with an electrode of the piezoelectric actuator (without an intervening switching semiconductor junction). In operation, the ejection transistor may be controlled so that a potential output from the ejection transistor is directly applied to an electrode of the piezoelectric actuator.

[0110] The control circuit system may be configured to receive an input control signal from outside the printhead and output an actuator control signal to each of the plurality of actuators to control ejection of ink from the plurality of printhead nozzles.

[0111] The printhead may include an electrical input for receiving an actuator drive pulse. In operation, the printhead may receive an actuator drive pulse.

[0112] The printhead may include a controller for controlling the printhead. The controller may include one or more microcontrollers or microprocessors, which may be integrated or distributed, in communication with or include a memory storing program code.

[0113] The controller may include a signal generator configured to generate actuator drive pulses (typically, a sequence of actuator drive pulses). Each printhead typically includes an electrical input connected to the controller through which the actuator drive pulses are received. In operation, the printhead assembly may generate actuator drive pulses (e.g., in the controller) and conduct the actuator drive pulses to the printhead via an electrical connection.

[0114] The actuator drive pulse is usually an analog signal. The actuator drive pulse usually contains a periodically repeating voltage waveform.

[0115] The control circuit system can be configured to switchably connect or disconnect at least one electrode of the or each of the plurality of piezoelectric actuators to a received actuator drive pulse, thereby selectively actuating the piezoelectric actuator. In operation, the print head can switchably connect or disconnect at least one electrode of the or each of the plurality of piezoelectric actuators to a received actuator drive pulse, thereby selectively actuating the piezoelectric actuator.

[0116] The controller may include one or more pulse generators that generate multiple sequences of actuator drive pulses, and the electrical input of the printhead receives multiple sequences of actuator drive pulses (generated by the one or more pulse generators) through multiple electrical connections to the controller, and the control circuit system is configured to switchably connect or disconnect at least one electrode of the or each of the multiple piezoelectric actuators to or from received actuator drive pulses selected from a plurality of different sequences of received actuator pulses. In operation, the printhead may generate multiple different sequences of actuator drive pulses (e.g., in the controller) and conduct them to the printhead through separate electrical connections, and switchably connect or disconnect at least one electrode of the or each of the multiple piezoelectric actuators to or from one or more received actuator drive pulses received from a variable sequence (and selectable sequence) of the multiple different sequences of actuator drive pulses.

[0117] The selection of which sequence of received actuator pulses to connect at least one electrode of a piezoelectric actuator may be responsive to stored data specific to the respective piezoelectric actuator and / or responsive to measurements of the operation of the respective piezoelectric actuator. Thus, the control circuitry may generally select whether each piezoelectric actuator ejects a droplet at each of a series of periodic droplet ejection decision points. By decision point, it is meant herein the time prior to the start of an actuator drive pulse during which it is determined whether to deliver an actuator drive pulse to at least one electrode of a particular piezoelectric actuator.

[0118] Typically, the actuator drive pulses repeat periodically. The actuator drive pulses may be amplified by the controller. The actuator drive pulses may not be amplified by the printhead. The printhead module may not generate the actuator drive pulses.

[0119] Typically, pulses from the pulse generator are conducted to multiple control circuits, which may be part of multiple print heads. Thus, a single pulse generator circuit may drive multiple piezoelectric transducers on the same substrate and / or multiple print heads having separate substrates, each having multiple piezoelectric transducers.

[0120] The digital actuation control signal is typically received from a controller. The digital actuation control signal is typically received through a flexible connector. The digital actuation control signal may be received in serial form and converted to a parallel control signal using a shift register within the control circuit system.

[0121] The controller may include a pulse generator configured to generate actuator drive pulses for transmission to the print head and digital control signals for transmission to the print head, and to process the digital control signals in a control circuit system of the print head to determine which actuator drive pulses are transmitted to at least one electrode of one or more piezoelectric actuators of one or more print head modules to cause droplet ejection.

[0122] In operation, the printhead assembly can generate actuator drive pulses (e.g., at a controller) and digital control signals and conduct both the actuator drive pulses and the digital control signals to the control circuit system of the printhead, and the control circuit system processes the digital control signals and, in response, conducts selected actuator drive pulses to at least one electrode of one or more piezoelectric actuators of one or more printheads to cause droplet ejection.

[0123] Thus, analog actuator drive pulses and digital control signals are typically input by control circuitry (and typically by the printhead module). Typically, the digital control signal is used to selectively switch the analog actuator drive pulses, thereby selectively transmitting them to the piezoelectric actuators.

[0124] In some embodiments, the control circuit system is configured to switchably connect one or more of ground and a single fixed non-zero voltage line or multiple fixed voltage lines with different voltages (one or more of which can be grounded) to one or two electrodes of the piezoelectric actuator to cause the printing agent to eject droplets. For example, the control circuit system can switch the electrode between a connection to ground and a connection to a fixed voltage or multiple fixed voltage lines with different voltages and back to ground again to cause droplet ejection. Typically, the second print head module is configured to conduct the ground and / or the single fixed non-zero voltage from the first print head module to the third print head module.

[0125] Switching an electrode between a connection to ground and a connection to a fixed voltage or between fixed voltage lines may involve operating a latch.

[0126] The control circuit system can be configured to individually and selectively actuate at least three (or at least four) of the piezoelectric actuator elements formed by one or more of the layers on the same substrate and defining portions of different corresponding fluid chambers (having different corresponding droplet ejection outlets, sometimes referred to as print head nozzles), optionally wherein the at least three (or at least four) actuator elements are configured for ejecting ink compositions of different colors or as redundant droplet ejection outlets.

[0127] The at least three (or at least four) piezoelectric actuator elements can be located on a substrate (optionally, adjacent to each other, optionally, in a row), and the control circuit system is connected to a flexible print head cable having one or more electrical signal conductors, wherein the control circuit system is configured to individually and selectively actuate actuator elements of the at least three (or at least four) piezoelectric actuator elements in response to an actuation command received via the same signal conductor.

[0128] Thus, due to the integration of the control circuitry configured to drive at least three (or at least four) actuator elements, individual signal conductors can transmit control signals that cause actuation of individual actuator elements of the at least three (or at least four) piezoelectric actuator elements. Typically, the control signal is a digital control signal.

[0129] The at least three (or at least four) piezoelectric actuator elements may include or be a group of piezoelectric actuator elements, for example, a group of piezoelectric actuator elements configured to eject the same ink composition (e.g., having chambers in fluid communication with the same ink supply) or ink compositions of different colors (e.g., having chambers in fluid communication with separate ink supplies), or a group of piezoelectric actuator elements divided into a plurality of (typically at least three or at least four) subgroups, wherein the piezoelectric actuator elements in each subgroup are configured to eject the same ink composition (e.g., having fluid chambers in fluid communication with the same fluid supply), and the piezoelectric actuator elements in some or all subgroups are configured to eject ink compositions of different colors (e.g., in fluid communication with separate ink supplies). The piezoelectric actuator elements in the same subgroup may be arranged in an array, and there may be a plurality of arrays of the corresponding subgroups.

[0130] The control circuitry may be configured to individually and selectively actuate at least twice as many piezoelectric actuator elements as signal conductors through which the control circuitry receives the actuation control signals.

[0131] The control circuitry may be configured to individually and selectively actuate at least 128 (or at least 256) piezoelectric actuator elements, and the control circuitry receives actuation control signals via at most 32 (or at most 16) signal conductors.

[0132] The control circuit system may include a serial-to-parallel conversion circuit configured to convert digital signals received in serial form via one or more signal conductors into selections of piezoelectric actuators to be actuated to eject droplets simultaneously (i.e., in parallel). The serial-to-parallel conversion circuit typically includes one or more shift registers.

[0133] Manufacturing of printing device and printing method

[0134] In another aspect of the present invention, a method of manufacturing a printing device is provided, the method comprising the following steps: (i) forming a control circuit system in a substrate; (ii) forming a plurality of piezoelectric actuators each electrically connected to the control circuit system; (iii) forming a plurality of nozzles, each of the plurality of nozzles being coupled to a corresponding piezoelectric actuator in the plurality of piezoelectric actuators; and (iv) forming a plurality of chambers, each of the plurality of chambers being fluidly connected to a corresponding nozzle in the plurality of nozzles. The different ink composition groups may be received or receivable in a plurality of chambers. The method may also include preparing different ink composition groups for the printing device. The ink composition may be prepared as described herein. The method may include receiving each of the different ink composition groups in a corresponding chamber in the plurality of chambers.

[0135] In another aspect of the present invention, there is provided a printing method comprising the following steps: (i) providing a printing device as described in the previous aspect; and (ii) operating the control circuit system to eject at least one (usually at least two) ink compositions according to the group of the second aspect from at least one nozzle (usually at least two nozzles) of a plurality of nozzles of a plurality of print head ejectors. Typically, ink droplets of at least two ink compositions from at least two nozzles of the plurality of nozzles are ejected at corresponding volumes and velocities. The printing device may be as described herein. The ink composition may be as described herein.

[0136] Where appropriate, any feature of one aspect of the present invention may be used in any other aspect of the present invention. Where appropriate, any feature of a particular embodiment may be used in any other embodiment of the present invention. Any optional feature (e.g., described as 'preferred' or 'typical' feature) should be understood to be particularly preferred in combination with one or more other optional features. Unless otherwise specified, any feature described should not be considered incompatible with any other feature unless such combination is obviously and inherently incompatible. It should generally be envisaged that each and every individual feature disclosed in the present invention can be combined with any other feature in any appropriate manner unless explicitly or clearly incompatible. The word 'comprising' is intended to mean 'including', but not necessarily 'consisting of' or 'composed of'. In other words, the steps or options listed do not have to be exhaustive. In the description and claims of this specification, unless the context otherwise requires or indicates, the singular encompasses the plural, and vice versa. Specifically, where an indefinite article is used, unless the context otherwise requires or indicates, the specification should be understood to take into account the plural as well as the singular. The examples and embodiments given in the above description are intended to illustrate the present invention, rather than to limit the present invention. Unless otherwise stated, all percentages are weight percentages based on the total weight of the relevant materials. Except in the operating and comparative examples or otherwise explicitly stated, all quantities indicating the amount of material or reaction conditions, physical properties or materials and / or use in this description should be understood to be modified by the word 'about'. Unless otherwise stated, numerical ranges expressed in the format of 'from x to y' should be understood to include x and y. When multiple optional ranges are described in the format of 'from x to y' for a particular feature, it should be understood that all ranges combining different endpoints are also considered. It will be understood that all possible combinations of the ranges and sub-ranges described herein are also considered. For example, a viscosity range not exceeding 20% ​​of the maximum viscosity value of the group is understood to be particularly preferably combined with any preferred density range, and further combined with any preferred surface tension range. For example, any preferred viscosity range is understood to be particularly preferably combined with any preferred density range, and further combined with any preferred surface tension range. For example, any optional range of volume is understood to be particularly preferably combined with any optional range of speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0137] Example embodiments of the present invention will now be described with reference to the following drawings, in which:

[0138] Figure 1 is a schematic diagram showing an arrangement of actuators, print head nozzles, and control circuitry as disclosed herein;

[0139] Figure 2 It includes multiple print head nozzles Figure 1 a diagram of the arrangement shown;

[0140] Figure 3 is a block diagram of control circuitry for a printhead as disclosed herein;

[0141] Figure 4 4a, 4b and 4c are graphical representations of actuator control signals for the circuit systems described herein;

[0142] Figure 5 is a flow chart of a process for matching a set of inks.

[0143] Reference now Figures 1 to 4 An integrated inkjet printhead useful with the present invention and its operation are described. Figure 1 1 is a schematic diagram showing the arrangement of the actuator, print head nozzles, and control circuitry. The drop ejector assembly 100 includes a silicon substrate 102 including a control circuitry 104 on a first surface 106 of the silicon substrate 102. The control circuitry 104 is typically an integrated circuit 104 in the form of a CMOS circuit 104. It will be appreciated by those skilled in the art that a CMOS circuit includes both doped regions of the substrate and metallization layers and interconnects formed on the first surface of the substrate. A plurality of layers, generally shown as 112, are formed on the first surface 106 of the silicon substrate 102. Layer 112 is a CMOS metallization layer and includes metal conductive traces and a passivation insulator, such as SiO2, SiN, SiON. The drop ejector assembly 100 further includes a piezoelectric actuator 118 including a piezoelectric 120, which in this example is formed of AlN or ScAlN, but may be formed of another suitable piezoelectric material processable at temperatures below 450°C. The piezoelectric actuator 118 forms a diaphragm having a layer of material such as silicon, silicon oxide, silicon nitride, or derivatives thereof, and has a passivation layer 160 (sometimes referred to as a nozzle defining layer 160) that prevents the applied electrical potential from contacting the fluid.

[0144] At least one metallization layer 112 includes interconnects to conduct signals from an external controller to the first portion 105a of the control circuit system 104 through the bonding pads 180, and to conduct signals from the second portion 105b and the third portion 150c of the control circuit system 104 to the piezoelectric actuator through the electrical interconnects 108, specifically to the first electrode 140 and the second electrode 142 arranged to apply a potential difference across the piezoelectric body 120 and thereby actuate the piezoelectric body. An opening 120a is defined in the piezoelectric body 120 for passing the electrical interconnect 108 between the second portion 105b of the control circuit system 104 and the second electrode 142.

[0145] The piezoelectric actuator 118 and the accompanying passivation layer 160 define the walls of the fluid chamber 122, which receives a printing agent, such as ink (in the case of an inkjet printer) or another printable fluid (for example, in the case of an additive manufacturing printer) through a conduit 124 and communicates with a print head nozzle 126 for ejecting the fluid. The piezoelectric actuator 118 and the nozzle defining layer 160 further define the walls of the print head nozzle 126. The conduit 124 forms a printing agent inlet ( Figure 1 ) and print head nozzle 126 (and additional print head nozzles, Figure 1 1 and 12. The conduit 124 is defined by the silicon substrate 102, the metallization layer 112, and the nozzle defining layer 160. The protective front surface 170 provides an outer surface of the drop ejector assembly 100, which is provided to cover and protect the piezoelectric actuator 118 and is adjacent to the surface 162 of the nozzle defining layer 160. The protective front surface 170 has an orifice that defines the nozzle 126. The piezoelectric actuator 118, the chamber 122, and the nozzle 126 together form a drop ejector generally shown as 101.

[0146] Typically, a CMOS control circuit comprises patterned areas of doped silicon and metallization layers. The number of metallization layers depends on the complexity of the CMOS control circuit, but for many applications three layers should be sufficient.

[0147] Although for the sake of clarity, Figure 1 Only one print head nozzle 126 and piezoelectric actuator 118 are shown in FIG. 1 , but it should be understood that a plurality of print head nozzles 126 and corresponding piezoelectric actuators 118 are provided, including actuators for dispensing a plurality of different inks. Each piezoelectric actuator 118 is configured to control the ejection of printing agent from a corresponding print head nozzle 126.

[0148] Figure 1 A droplet ejector ejects an ink composition through a nozzle. The piezoelectric transducer is located in a nozzle defining layer that moves with the nozzle. Therefore, the surface of the chamber 122 including the nozzle moves during actuation. This is in contrast to a device in which the surface including the nozzle does not move while another surface (e.g., an opposing surface) is actuated. As a result, only a very small actuation force is required to displace the ink in the nozzle. The ink is then ejected from the nozzle primarily by inertial forces (i.e., inertial ejection). In this article, ejection by inertial forces may also be referred to as inertial ejection or ejection by inertial mode. The ejection of the ink is primarily determined by the density and viscosity of the ink rather than the compressibility, which would be the case if another surface was actuated and the ink in the chamber was displaced as a whole.

[0149] Figure 2A print head including a plurality of nozzles is shown. Figure 1 Specifically, refer to Figure 2 , which shows a printhead 100a having a plurality of drop ejectors 101 (individual piezoelectric actuators, fluid chambers, and drop ejection outlets), a flexible cable interconnect 138 having a limited number of signal conductors connects an external controller to the printhead 100a containing a plurality of drop ejectors shown as 101 by wires to eject different printing agents, such as inks of different colors. The chambers (122a, b, c, and d) may contain inks of different colors. The piezoelectric actuators 118, control circuitry 104, and printhead nozzles 126 forming the plurality of drop ejectors 101 are typically formed from a single CMOS / actuator substrate, but the printing agent manifold of each printhead 100a may be at least partially defined by at least one additional component disposed in fluid communication with the printhead nozzles 126. In these examples, as well as the main portion of the CMOS control circuit 104, the CMOS control circuit includes a separate circuit element 104' associated with each drop ejector, which may, for example, include a latch and an ejector transistor for each piezoelectric actuator.

[0150] Figure 3 1 is a block diagram of a control circuit system for a print head assembly. In this example, actuator control is distributed between a machine controller 220 and a control circuit system (e.g., a CMOS circuit) 104 within the print head 100a. They are connected in part by conductors extending through a single or multiple flexible cable interconnects 138. Multiple actuators 120 are controlled by applying potentials to their electrodes 140, 142. The machine controller includes at least a processor 200, such as a microprocessor or microcontroller, having a memory 202 storing relevant data and program code. A wired or wireless electronic interface 204 receives input data from an external device driver. It should be understood by those skilled in the art that the machine controller can be distributed between several separate components or functional modules, such as one component that converts an image into a pixelated pattern for printing using, for example, a dither matrix, and a separate component that converts the pixelated pattern into a print pattern for different nozzles.

[0151] The machine controller includes a waveform generator and a voltage amplifier 208 that transmits the actuator control pulses ( Figure 4 Although the machine controller is capable of generating a variety of different waveforms, in the context of the present invention, it is advantageous to generate and use a single waveform to eject each type of ink because this reduces wiring and provides other benefits as described above.

[0152] A ground conductor 212 also extends from the machine controller to the drop ejector assembly 100. (The ground connection within the printhead is not shown for clarity.) The processor 200 typically generates digital control signals 214 as a serial bus and also transmits a clock signal 216 to the printhead that is used to synchronize printing with the movement of the printhead. The connector also provides voltage levels associated with the operating voltages of the CMOS control electronics.

[0153] Within the printhead 100a, the contact pads 136 are connected to the conductors of the flexible connector, and signals are transmitted from the patterned metallization layer 112 to the CMOS control circuit 104 and from the CMOS control circuit to the electrodes 140, 142, thereby actuating the individual piezoelectrics 120 within the corresponding piezoelectric actuators. The control circuit 104 on the substrate 102 includes an ejection switch circuit 220, which includes an ejection transistor having an output terminal that is directly electrically connected to the electrodes 140, 142 (i.e., without another intervening switching semiconductor junction). The ejection switch circuit switches the actuator control pulse signal, and if one of the electrodes remains connected to ground, the ejection switch circuit can be as simple as a single transistor per actuator or a single transistor per electrode to switch the signal applied to the electrode. The ejection switch circuit can be distributed around the substrate, with a portion (e.g., a transistor, or a transistor and a latch) close to each drop ejector.

[0154] The jet switch circuit does not perform power amplification. Instead, it switches the actuator control pulses, thereby determining for each pulse whether each pulse is relayed to the corresponding actuator. Voltage amplification is performed in the machine controller by amplifier 208.

[0155] The jet switching circuit is controlled by a latch and shift transistor 222, which receives and stores digital data from a control circuit 224, which processes the received data, for example, converts the received serial data, stores the data in a register 226, and uses the received data to determine which actuators to actuate during each consecutive actuator activation event. The control circuit 228 also stores fine-tuning data for customizing the precise timing of the voltage switches for each actuator, which is typically determined during a calibration step at setup, and may store configuration data 230 indicating the physical layout of the nozzles, safety information, and or nozzle actuation count history information. The control circuit 224 also receives data from sensors 232, 234, 236, some of which are associated with individual actuators, such as nozzle fill level sensors, and some of which sense parameters related to the function of the entire print head, such as temperature sensors.

[0156] Figure 4(a), 4(b) and 4(c) show three possible drive waveforms generated by the waveform generator or voltage amplifier 206 in an alternative embodiment. The x-axis is time (in milliseconds) and the y-axis is the potential per μm thickness of the actuator. Because the piezoelectric is made of a non-ferroelectric material in this example, the pulse can be applied in either direction. Figure 4 In (a), the signal has a default voltage of 0, and after a predetermined period of time, each pulse switches to a positive potential and returns to zero. Figure 4 In (b), the signal has a default voltage of 0 and is first switched to a positive potential (to deform the piezoelectric actuator in one direction), and then to a negative potential (to deform the piezoelectric actuator in the opposite direction), before returning to zero. Figure 4 In (c), the signal has a default voltage of 200 V and switches to a voltage of -200 V (reversing the direction of the electric field in the piezoelectric) before returning to 200 V.

[0157] During operation, the processor 200 receives print data such as a bitmap in digital form via the interface 204, and processes this data in a known manner to send a series of print instructions to each print head via the serial connection 216. These print instructions can be as detailed as instructions for each print head regarding whether and when to eject droplets during a print cycle. In one embodiment, a waveform generator generates repetitive voltage pulses suitable for application to electrodes of individual piezoelectric actuators. These pulses are periodic, with time intervals that determine the time between droplet ejection events on the print head. Alternatively, a voltage amplifier 208 can provide a single voltage level from a plurality of voltage levels to the print head assembly, and maintain the single voltage level. The ejection transistors within the print head will switch these voltages according to the CMOS control circuit.

[0158] Since the waveform generator or generators are not located on the printhead and are used to drive a large number of piezoelectric actuators, they can generate a lot of heat without causing problems. There are no significant substrate space constraints, so it can be a relatively complex circuit adapted to carefully control the shape of the waveform with a selected and optionally variable slew rate, and the power amplifier can be selected to produce the desired voltage up to the maximum possible current requirement if all actuators that can be actuated simultaneously can be actuated together.

[0159] Control circuitry 224 on the individual printhead substrate receives print instructions via serial connection 216 and processes these instructions (e.g., converts from serial instructions to parallel instructions). With reference to clock signal 214, it is determined whether each individual piezoelectric actuator should be actuated to eject a droplet during each print cycle, and this data is loaded into latch 222. At the appropriate time during each print cycle, the latched data is passed to the ejection switch circuit, which electrically switches the received print waveform to the electrode of the corresponding actuator element, causing the electrode to perform a drop ejection cycle, or not, in which case both electrodes of the corresponding actuator element remain connected to ground and the drop ejector does not perform a drop ejection cycle.

[0160] The sensors 232, 234, 236 are monitored during printing. The precise timing of switching the received printing waveform to the electrodes of the corresponding actuator elements may be varied in response to measuring temperature using the temperature sensitive CMOS element.

[0161] The shift register moves the droplet firing pattern information to the latch register. Thus, the shift register interfaces with the serial connection and moves all print data to the latch register in a given print cycle. The latch register interfaces with the ejection register to initiate a print command.

[0162] In some embodiments, instead of the machine controller including a waveform generator and conducting the waveform to the printhead and CMOS control circuitry thereon, the CMOS control circuitry actuates the piezoelectric actuators by switching a voltage applied to one or more of the electrodes of each piezoelectric actuator, for example between ground and a fixed voltage, or between a plurality of fixed voltage levels (one or more of which may be grounded), thereby causing droplet ejection. In this case, the flexible connector 138 contains one or more electrical conductors that carry the fixed voltage from the machine controller to the printhead.

[0163] Figure 5 shows a matching Figures 1 to 4Flowchart 500 of a method for printing multiple inks in a device of the invention. First, characteristics of ink drops (e.g., the size of the ink drops) are defined 510. A set of target physical characteristics (i.e., viscosity, density, and surface tension) of the ink is determined 520 (used as physical characteristic criteria) using the defined characteristics coupled to the droplet ejection waveform 510'. Next, a candidate group of ink compositions (e.g., a candidate group of different ink compositions) can be determined 530. The candidate group can be, for example, a group of inks that have been manufactured with appropriate ingredients at relevant levels that have been designed to achieve the target physical characteristics. Alternatively, the candidate group can be a random group of inks. After 530, the physical characteristics (i.e., viscosity, density, and surface tension) of the candidate group are determined 540. In general, these characteristics can be determined by using the methods described herein or any suitable and effective method known to a skilled person. If the characteristics of the candidate ink groups match each other and match the target physical characteristics 550, the candidate group is selected 570. Otherwise, one or more inks (e.g., all inks) in the candidate group are modified 560, and the physical characteristics of the one or more inks are determined again 540. The modification may be suitably performed by adjusting the type and / or level of appropriate ingredients (e.g., surfactants, carriers, and rheology modifiers). If, after modification, the candidate set still does not meet the matching requirements 550, the set may be modified again 560. In this manner, steps 540, 550, and 560 may be repeated one or more times as appropriate until an ink set is selected 570. The selected set may be put into use (e.g., placed in a chamber of a printhead as described herein), and the specifications of the ink set may be used to manufacture a corresponding ink set, which may be packaged into an ink cartridge where appropriate. The ink cartridge may contain each ink in the set.

[0164] Detailed description of ink set

[0165] The invention will be illustrated by the following non-limiting examples.

[0166] The ingredients in Table 1 can be used in the ink composition.

[0167] Table 1: Ingredients

[0168]

[0169] An exemplary ink composition set is shown in Table 2.

[0170] Table 2: Ink composition group

[0171]

[0172] The weight percentages shown in the morning are based on the total weight of the ink composition. For a target dpi (e.g., 1200), the target viscosity, density, and surface tension of each ink composition are determined experimentally or theoretically. Narrow ranges (e.g., 1% variation) of viscosity, density, and surface tension are determined. These ranges depend largely on the embodiment and can be a viscosity range of 1.5 mPa·s-20 mPa·s, a viscosity range of 650 kg / m 3 -1750 kg / m 3 Any value in the density range and surface tension range of 20mN / m-75mN / m.

[0173] The amount of each component is adjusted so that the viscosity, density and surface tension of all compositions C1-C4 are within a narrow target range. These values ​​are measured according to the method described herein. Therefore, the values ​​of viscosity, density and surface tension of compositions C1-C4 are matched in such a way that the difference between any two compositions does not exceed 1% of the maximum corresponding value of the group (i.e., matching these values ​​according to the present invention). However, because the compressibility is not critical, the variation of the compressibility between different compositions C1-C4 in the group is allowed to vary and can be greater than 1% or greater. No precise tolerance of the compressibility is required, which is conducive to optimizing the more important viscosity, density and surface tension parameters.

Claims

1. An integrated inkjet printhead for ejecting different sets of ink compositions, wherein the printhead comprises at least one substrate, and the substrate comprises a plurality of ejectors, each of the plurality of ejectors comprising: (i) a nozzle; (ii) a chamber for receiving an ink composition in the set, wherein the chamber is in fluid communication with the nozzle; and (iii) a piezoelectric actuator coupled to the nozzle to selectively eject the ink composition from the nozzle, wherein each ejector is configured to eject ink drops of the different ink compositions at corresponding volumes and velocities.

2. The integrated inkjet printhead according to claim 1, wherein each ejector is configured to eject an ink composition satisfying a plurality of physical property criteria at a corresponding volume and velocity, the physical property criteria including at least a corresponding density and viscosity.

3. An integrated inkjet printhead according to claim 1 or claim 2, wherein the configuration of the ejector includes an actuation waveform of the actuator in use, and the actuation waveform generally includes a time-varying displacement of the ink composition in the chamber and a force applied to the ink composition during actuation.

4. An integrated inkjet print head according to any preceding claim, wherein the substrate comprises CMOS control circuitry, a plurality of layers on a first surface of the substrate, the piezoelectric actuator being formed by one or more of the layers, and the nozzle comprising a hole through one or more of the layers, such that the piezoelectric actuator, in use, displaces one or more of the layers and the nozzle to thereby eject an ink composition in an inertial mode.

5. An integrated printhead according to any preceding claim, comprising at least 100 ejectors, preferably at least 1000 ejectors.

6. A set of different ink compositions for use in an integrated inkjet printhead according to any preceding claim, wherein: (i) the viscosity values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 20%, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1% of the maximum viscosity value of the group; (ii) the density values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 20%, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1% of the maximum density value of the group; and (iii) the surface tension values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 20%, preferably does not exceed 10%, more preferably does not exceed 5%, and most preferably does not exceed 1% of the maximum surface tension value of the group.

7. A set of different ink compositions according to claim 6, wherein the set comprises a plurality of compositions, each of the plurality of compositions comprising a different colorant, the colorant being selected from cyan (C), yellow (Y), magenta (M), black (K), red (R), green (G), blue (B), violet, orange, gold, silver, white and mixtures thereof, preferably selected from CYMK and mixtures thereof, or selected from RGBK and mixtures thereof, and optionally, wherein the weight percentages of the colorants contained in at least two compositions in the set or in any two compositions in the set differ by no more than 5, or by no more than 2, or by no more than 1 or by no more than 0.1, and any weight percentages are based on the total weight of the respective ink composition.

8. A set of different ink compositions according to claim 7, wherein the set comprises a first composition comprising a cyan (C) or red (R) colorant, a second composition comprising a yellow (Y) or green (G) colorant, a third composition comprising a magenta (M) or blue (B) colorant, and a fourth composition comprising a black (K) colorant.

9. A set of different ink compositions according to any one of claims 6 to 8, wherein at least one composition in the set or each composition in the set comprises a rheology modifier, and / or a surfactant and / or a carrier, and optionally, wherein the weight percentages of the rheology modifier, and / or the surfactant and / or the carrier contained in at least two compositions in the set or any two compositions in the set differ by no more than 20, or by no more than 10, or by no more than 5, or by no more than 1, and any weight percentages are based on the total weight of the respective ink composition.

10. The set of different ink compositions according to claim 9, wherein at least two compositions in the set or any two compositions in the set comprise rheology modifiers that are different from each other, and / or surfactants that are different from each other and / or carriers that are different from each other, and optionally, wherein the difference in weight percentages of the rheology modifiers, and / or the surfactants and / or the carriers contained in at least two compositions in the set or any two compositions is at least 0.1, or at least 1, or at least 5 or at least 10, and any weight percentages are based on the total weight of the respective ink composition.

11. A printing device comprising an integrated print head according to any one of claims 1 to 5; a signal generator configured to generate a drive signal having a repetitive waveform; and a control circuit system configured to relay the drive signal to the actuator through a switch and control the switch to selectively apply the drive signal to individual actuators to thereby eject ink droplets of the different ink compositions at corresponding volumes and speeds.

12. The printing apparatus according to claim 11, further comprising an ink composition set according to any one of claims 6 to 10, wherein the composition is received or receivable in the chamber.

13. A printing method comprising the following steps: (i) providing a printing device according to claim 11 or claim 12; and (ii) operating the control circuit system to eject at least two ink compositions in the group according to any one of claims 6 to 10 from at least two of the multiple nozzles of the multiple print head ejectors, whereby ink droplets of the at least two different ink compositions are ejected from the at least two of the multiple nozzles at corresponding volumes and velocities.

14. A method for preparing a set of different ink compositions according to any one of claims 6 to 10, the method comprising the steps of: (i) preparing at least two ink compositions; (ii) determining whether the viscosity values, density values ​​and surface tension values ​​of the at least two ink compositions are such that the set of the at least two ink compositions is a set of different ink compositions according to any one of claims 6 to 10; and (iii) if this is not the case, modifying at least one of the at least two ink compositions one or more times until the set is a set of different ink compositions according to any one of claims 6 to 10.

15. A method for selecting a different set of ink compositions according to any one of claims 6 to 10, the method comprising the steps of: (i) defining at least one property of the jetted ink droplets; (ii) determining target values ​​for viscosity, density and surface tension of the ink composition using the at least one defined property; and (iii) selecting at least two ink compositions with reference to the target values ​​as described in step (ii), wherein the values ​​of the at least two ink compositions are such that the set of the at least two ink compositions is a different set of ink compositions according to any one of claims 6 to 10.

16. A set of different ink compositions according to any one of claims 6 to 10, wherein: (i) the viscosity values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 10%, preferably does not exceed 5%, and more preferably does not exceed 1% of the maximum viscosity value of the group; (ii) the density values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 10%, preferably does not exceed 5%, and more preferably does not exceed 1% of the maximum density value of the group; and (iii) the surface tension values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 10%, preferably does not exceed 5%, and more preferably does not exceed 1% of the maximum surface tension value of the group.

17. The set of different ink compositions according to claim 16, wherein: (i) the viscosity values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 5%, preferably does not exceed 1%, of the maximum viscosity value of the group; (ii) the density values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 5%, preferably does not exceed 1% of the maximum density value of the group; and (iii) the surface tension values ​​of the compositions are matched in such a way that the difference between any two compositions does not exceed 5%, preferably does not exceed 1% of the maximum surface tension value of the group.

18. A set of different ink compositions according to any one of claims 6 to 10, 16 and 17, wherein the difference in compressibility (k) between two ink compositions in the set or any two ink compositions in the set is at least 1%, or at least 5%, or at least 10%, or at least 20%, or at least 30%, or at least 40% or at least 50% of the maximum compressibility value of the set.

19. The set of different ink compositions according to claim 18, wherein the difference in compressibility (k) of the two ink compositions in the set or any two ink compositions in the set is at least 5% or 10% of the maximum compressibility value of the set.

20. A printing device comprising an integrated print head according to any one of claims 1 to 5 and a set of different ink compositions according to any one of claims 6 to 10 and 16 to 19, wherein the compositions are received or receivable in the chamber.

21. The printing apparatus according to claim 20, wherein the set of different ink compositions is according to any one of claims 17 to 19.

22. A printing device according to claim 20 or claim 21, further comprising a signal generator configured to generate a drive signal having a repetitive waveform; and a control circuit system configured to relay the drive signal to the actuator via a switch and control the switch to selectively apply the drive signal to individual actuators to thereby eject ink droplets of the different ink compositions at corresponding volumes and speeds.

23. The printing apparatus according to claim 22, wherein the set of different ink compositions is according to any one of claims 17 to 19.

24. A printing method, comprising: providing a printing device according to claim 22 or claim 23; and operating the control circuit system to eject at least two ink compositions of the different ink composition groups from at least two of the multiple nozzles of the multiple print head ejectors, whereby ink droplets of the at least two different ink compositions are ejected from the at least two of the multiple nozzles at corresponding volumes and velocities.

25. A method for preparing a different ink composition set for a printing device according to any one of claims 20 to 23, the method comprising: preparing at least two ink compositions; determining whether the viscosity values, density values ​​and surface tension values ​​of the at least two ink compositions are such that the at least two ink compositions are the different ink composition set; and (iii) if this is not the case, modifying at least one of the at least two ink compositions one or more times until the at least two ink compositions are the different ink composition set.

26. A method for selecting different ink composition sets for a printing device according to any one of claims 20 to 23, the method comprising: defining at least one characteristic of the ejected ink droplets; determining target values ​​for viscosity, density and surface tension of the ink composition using the at least one defined characteristic; and selecting at least two ink compositions with reference to the target values, wherein the values ​​of the at least two ink compositions are such that the at least two ink compositions are the different ink composition sets.

27. A method for manufacturing a printing device according to any one of claims 11, 12 and 20 to 23, the method comprising: forming a control circuit system in a substrate; forming a plurality of piezoelectric actuators each electrically connected to the control circuit system; forming a plurality of nozzles, each of the plurality of nozzles being coupled to a corresponding piezoelectric actuator among the plurality of piezoelectric actuators; and forming a plurality of chambers, each of the plurality of chambers being fluidly connected to a corresponding nozzle among the plurality of nozzles.

28. A method of manufacturing a printing device according to claim 27, further comprising the method of preparing a set of different ink compositions according to claim 14 or claim 25.

29. The method of claim 28, further comprising receiving each of the different ink composition sets in a corresponding chamber of the plurality of chambers.

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