Ink viscosity determination method, device and printer

Abstract

The application discloses an ink viscosity determination method and device and a printer. In the method, the discovery that the ink viscosity can significantly affect the structural vibration characteristics of a piezoelectric nozzle is utilized, a structural vibration fluctuation signal used for representing the structural vibration characteristics of the piezoelectric nozzle is utilized, the ink viscosity in the piezoelectric nozzle is determined, the self-sensing measurement of the piezoelectric nozzle on the internal ink viscosity is realized, a feasible way is provided for the closed-loop feedback regulation of the jet performance and the precise control of the ink viscosity, and the reliability of the piezoelectric inkjet printing technology in emerging applications such as printed electronics and sensors can be promoted. The method comprises the following steps: detecting a structural vibration fluctuation signal of a piezoelectric nozzle, wherein the structural vibration fluctuation signal is used for representing the structural vibration characteristics of the piezoelectric nozzle; and determining the ink viscosity in the piezoelectric nozzle according to the structural vibration fluctuation signal.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of piezoelectric inkjet technology, and in particular to an ink viscosity determination method and device and a printer. BACKGROUND

[0002] Piezoelectric inkjet printing is a material deposition technique commonly used in electronic additive manufacturing technology, which is widely used due to its high material deposition accuracy, good jet controllability, wide material compatibility and low cost, such as printed electronic devices, sensors and solar cells and other applications.

[0003] In piezoelectric inkjet printing technology, a voltage waveform drives a piezoelectric actuator to generate a pressure wave in the ink, which in turn drives the ink at the nozzle to be ejected and form droplets. In this process, viscosity represents the stickiness of the ink, and its stickiness is the main factor that prevents fluid movement and consumes pressure wave energy. When the pressure wave energy matches the ink viscosity, a single droplet of ink can be produced, and when the pressure wave energy does not match the ink viscosity, it will cause inkjet defects (too large to form satellite droplets, too small to form droplets). Therefore, the matching of pressure wave energy and ink viscosity is the premise of high-precision material deposition. Since the energy of the pressure wave is generated by the voltage waveform driving the piezoelectric actuator, the matching of the pressure wave energy and the ink viscosity can actually be understood as the matching of the voltage waveform and the ink viscosity.

[0004] In traditional inkjet printing, an open-loop feedforward control strategy is usually used to complete the matching of the voltage waveform and the ink viscosity, i.e. the voltage waveform and the ink viscosity are pre-matched, and will remain unchanged in the subsequent ejection process. The premise for this control method to work well is that the ink viscosity remains stable during the forming process, but in emerging applications of inkjet-based additive manufacturing (such as printing antennas, sensors, etc.), the ink materials used to form functional devices are mostly nanoparticle-based inks (such as nanogold, nanosilver ink for printing conductive structures), and after material deposition, the solvent needs to be evaporated by heating the substrate to complete the layer-by-layer patterning distribution of the functional material. Due to the sensitivity of the ink viscosity to temperature (~2 cp / ℃) and the difference (different inks have different sensitivities), the heated substrate often causes the viscosity of the ink inside the nozzle to be difficult to remain stable, and the pre-set voltage waveform no longer matches the ink viscosity, making it difficult for the ink to be ejected, the consistency and stability of the ejected droplets deteriorate, and the performance of the inkjet-based additive manufacturing is limited.

[0005] In order to improve the viscosity range of the ink that can be jetted, a partial piezoelectric jet head usually integrates a heating module inside the piezoelectric jet head for heating the ink inside the nozzle to reduce the viscosity of the ink to the jettable range of the piezoelectric jet head. However, due to the lack of an effective ink viscosity sensing method, the viscosity of the ink after heating of the existing jet head can only be roughly estimated, and the estimation accuracy depends on a large number of preliminary experiments. In addition, under the excitation of the voltage waveform, the piezoelectric actuator continuously works in a high-frequency vibration state, and the energy loss of the vibration structure itself will be converted into heat. This mechanical loss also affects the temperature of the ink, thereby changing the viscosity of the ink. Therefore, the ink in the piezoelectric jet head faces a complex process thermal environment in actual application, and the viscosity of the ink is difficult to remain constant. The traditional open-loop feedforward control strategy is difficult to achieve stable deposition of the material, and due to the lack of an effective ink viscosity sensing method, the closed-loop feedback control strategy is also difficult to construct. Therefore, how to identify the viscosity of the ink inside the piezoelectric jet head becomes a technical problem to be solved urgently.

[0006] Currently, some commercial products add an independent viscosity identification system at the back end of the piezoelectric jet head to achieve the best printing effect through viscosity identification. However, due to the viscosity change caused by the time-varying temperature, the viscosity identification system located at the back end cannot sense the viscosity of the fluid inside the nozzle. In addition, some research and development of viscosity identification systems based on MEMS technology (Micro-Electro-Mechanical Systems, mainly including cantilever type and diaphragm type) reduce the size of the viscosity sensing unit from tens of centimeters to sub-millimeter scale. However, due to the characteristic size of the piezoelectric jet head nozzle is usually only tens of microns, it is difficult to integrate additional MEMS viscosity sensing units inside the piezoelectric jet head. How to sense the viscosity of the ink inside the nozzle is still a technical problem to be solved urgently. SUMMARY

[0007] Therefore, the present application provides an ink viscosity determination method, device and printer. The method uses the discovery that the viscosity of the ink significantly affects the structural vibration characteristics of the piezoelectric jet head, uses the structural vibration fluctuation signal for characterizing the structural vibration characteristics of the piezoelectric jet head to determine the viscosity of the ink in the piezoelectric jet head, realizes the self-sensing measurement of the piezoelectric jet head to the internal ink viscosity, provides a feasible way for the closed-loop feedback regulation of the jet performance and the accurate control of the ink viscosity, and can promote the reliability of the piezoelectric inkjet printing technology in emerging applications such as printed electronics and sensors.

[0008] According to one aspect of the present application, an ink viscosity determination method is provided, comprising:

[0009] detecting a structural vibration fluctuation signal of a piezoelectric jet head, the structural vibration fluctuation signal being used to characterize the structural vibration characteristics of the piezoelectric jet head;

[0010] Determine the ink viscosity in the piezoelectric inkjet head according to the structural vibration fluctuation signal.

[0011] In some embodiments, the step of detecting the structural vibration fluctuation signal of the piezoelectric inkjet head comprises:

[0012] Input a voltage waveform of a preset frequency into the self-sensing measurement circuit to output the structural vibration fluctuation signal;

[0013] The self-sensing measurement circuit comprises a first branch, a second branch, and a differential amplifier. The first branch comprises a piezoelectric actuator corresponding circuit and a first trans-impedance operational amplifier connected to the output end of the piezoelectric actuator corresponding circuit. The second branch comprises a ceramic capacitor and a second trans-impedance operational amplifier connected to the output end of the ceramic capacitor. The output end of the first trans-impedance operational amplifier and the output end of the second trans-impedance operational amplifier are respectively connected to the input end of the differential amplifier. The ceramic capacitor and the static capacitance of the piezoelectric actuator in the piezoelectric actuator corresponding circuit have the same capacitance value.

[0014] In some embodiments, the step of determining the ink viscosity in the piezoelectric inkjet head according to the structural vibration fluctuation signal of the piezoelectric inkjet head comprises:

[0015] Determine the corresponding gain voltage according to the structural vibration wavelength signal;

[0016] Determine the ink viscosity in the piezoelectric inkjet head according to the gain voltage.

[0017] In some embodiments, the step of determining the corresponding gain voltage according to the structural vibration wavelength signal of the piezoelectric inkjet head comprises:

[0018] Input the structural vibration wavelength signal and the voltage waveform into a gain detection module respectively to output the gain corresponding voltage value;

[0019] Input the gain corresponding voltage value into an analog-to-digital conversion module to output the gain voltage.

[0020] In some embodiments, the preset frequency is the resonant frequency of the piezoelectric inkjet head.

[0021] In some embodiments, the method further comprises:

[0022] Set the sweep frequency parameters, wherein the sweep frequency parameters comprise the scan start frequency, the end frequency, and the scan step;

[0023] Determine the excitation voltage waveform corresponding to different frequencies according to the sweep frequency parameters;

[0024] Determine the target gain voltage of the excitation voltage waveform corresponding to different frequencies;

[0025] determining whether a resonance peak exists in an amplitude-frequency curve formed by a target gain voltage of the excitation voltage waveform corresponding to the different frequencies;

[0026] If the resonance peak exists, a frequency corresponding to the resonance peak is determined as the resonance frequency.

[0027] If the resonance peak does not exist, the step of setting the sweep parameter is re-executed until the resonance frequency is determined, and the re-set sweep parameter is different from the historically set sweep parameter.

[0028] In some embodiments, the step of determining the ink viscosity in the piezoelectric printhead according to the gain voltage comprises:

[0029] determining the ink viscosity by using a mapping relationship of the gain voltage; wherein the determination method of the mapping relationship comprises:

[0030] determining preset gain voltages under different preset ink viscosities to form a target curve;

[0031] determining a maximum preset gain voltage and a minimum preset gain voltage in the target curve;

[0032] segmenting the target curve according to the maximum preset gain voltage and the minimum preset gain voltage to obtain a plurality of sub-curves;

[0033] determining a preset gain voltage corresponding to a starting point of the sub-curve;

[0034] determining a conversion coefficient corresponding to the sub-curve by using the preset gain voltage corresponding to the starting point of the sub-curve and the preset ink viscosity on the sub-curve;

[0035] determining a mapping relationship between the gain voltage and the ink viscosity according to the preset gain voltage corresponding to the starting point of the sub-curve and the conversion coefficient corresponding to the sub-curve.

[0036] In some embodiments, the step of determining the ink viscosity in the piezoelectric printhead according to the gain voltage comprises:

[0037] determining the ink viscosity by using a mapping relationship of the gain voltage; wherein the determination method of the mapping relationship comprises:

[0038] determining preset gain voltages under different preset ink viscosities to form a target curve;

[0039] fitting the target curve to obtain a mapping relationship between the gain voltage and the ink viscosity.

[0040] According to still another aspect of the present application, there is provided an ink viscosity determination device, comprising:

[0041] a detection unit configured to detect a structural vibration fluctuation signal of the piezoelectric inkjet head, the structural vibration fluctuation signal being used to characterize a structural vibration characteristic of the piezoelectric inkjet head;

[0042] a determination unit configured to determine the ink viscosity in the piezoelectric inkjet head according to the structural vibration fluctuation signal.

[0043] According to yet another aspect of the present application, there is provided a storage medium having stored therein at least one executable instruction, which causes a processor to perform the ink viscosity determination method as described.

[0044] According to yet another aspect of the present application, there is provided a printer comprising a piezoelectric inkjet head, a processor, a memory, a communication interface and a communication bus, the processor, the memory and the communication interface being capable of communicating with each other through the communication bus.

[0045] The memory is configured to store at least one executable instruction, which causes the processor to perform the ink viscosity determination method as described.

[0046] The present application provides an ink viscosity determination method, device and printer, which utilizes the discovery that ink viscosity can significantly affect the structural vibration characteristic of a piezoelectric inkjet head, utilizes a structural vibration fluctuation signal used to characterize the structural vibration characteristic of the piezoelectric inkjet head to determine the ink viscosity in the piezoelectric inkjet head, realizes self-perception measurement of the piezoelectric inkjet head on the internal ink viscosity, provides a feasible approach for closed-loop feedback regulation of jet performance and precise control of ink viscosity, and can promote the reliability of piezoelectric inkjet printing technology in emerging applications such as printed electronics and sensors.

[0047] The above description is only a summary of the technical solutions of the present application. In order to enable one of ordinary skill in the art to better understand the technical means of the present application and implement it according to the content of the description, and in order to enable the above and other purposes, characteristics and advantages of the present application to be more apparent, the following specific embodiments of the present application are described in detail. BRIEF DESCRIPTION OF DRAWINGS

[0048] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not meant to limit the present application. Furthermore, the same reference numerals are used throughout the several views to denote the same or similar parts. In the drawings:

[0049] Figure 1 An exemplary flowchart of an ink viscosity determination method according to some embodiments is shown;

[0050] Figure 2An exemplary schematic diagram showing the working principle of a piezoelectric inkjet head according to some embodiments is shown;

[0051] Figure 3 An exemplary schematic diagram showing the principle of a self-sensing measurement circuit according to some embodiments is shown;

[0052] Figure 4 An exemplary schematic diagram showing the principle of a piezoelectric actuator according to some embodiments is shown;

[0053] Figure 5 An exemplary schematic diagram showing the structure of a piezoelectric inkjet head vibration signal measurement system according to some embodiments is shown;

[0054] Figure 6 An exemplary schematic diagram showing the effect of ink viscosity on the amplitude of a piezoelectric inkjet head according to some embodiments is shown;

[0055] Figure 7 An exemplary flowchart showing another ink viscosity determination method according to some embodiments is shown;

[0056] Figure 8 An exemplary schematic diagram showing a target curve according to some embodiments is shown;

[0057] Figure 9 An exemplary schematic diagram showing another target curve according to some embodiments is shown;

[0058] Figure 10 An exemplary schematic diagram showing yet another target curve according to some embodiments is shown;

[0059] Figure 11 An exemplary schematic diagram showing the amplitude-frequency curve of a MJ-AL-80 piezoelectric inkjet head according to some embodiments is shown;

[0060] Figure 12 An exemplary schematic diagram showing the gain voltage variation under temperature interference according to some embodiments is shown;

[0061] Figure 13 An exemplary schematic diagram showing the fitting effect of a mapping equation according to some embodiments is shown;

[0062] Figure 14 An exemplary schematic diagram showing four ink viscosities according to some embodiments is shown;

[0063] Figure 15 An exemplary schematic diagram showing the structure of an ink viscosity determination device according to some embodiments is shown;

[0064] Figure 16Fig. 1 shows a schematic diagram of a terminal according to an embodiment of the present application. DETAILED DESCRIPTION

[0065] Exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be embodied in various forms without being limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0066] In the related art, the viscosity of the ink inside the piezoelectric nozzle is determined, and the following problems exist: (1) unable to perceive the viscosity of the ink: the existing piezoelectric nozzle cannot integrate additional sensors, and after the viscosity of the internal ink changes due to temperature and material stability, the piezoelectric nozzle cannot perceive the change in ink properties, which will cause the material deposition performance to deviate from the expected value; (2) poor material deposition reliability: the material deposition quality of piezoelectric inkjet is highly related to the viscosity of the ink, and changes in the viscosity of the ink will cause changes in the behavior of the jet, making it difficult to guarantee the consistency of material deposition, and it is difficult to obtain highly consistent forming effects for multiple inkjetting of the same pattern, and the reliability of material deposition is difficult to guarantee; (3) unable to avoid process thermal interference: in emerging applications of piezoelectric inkjet printing technology, process thermal interference is an environmental factor that piezoelectric nozzles must face. Changes in the viscosity of the ink caused by process heat will cause material deposition quality to deteriorate and become unstable; (4) unable to accurately regulate the viscosity of the ink: the heating module integrated inside the piezoelectric nozzle can lower the viscosity of the ink by heating it, so that the piezoelectric nozzle can jet higher viscosity ink, but due to the lack of an effective ink viscosity sensing method, the specific viscosity of the ink after heating cannot be accurately sensed; (5) unable to build a closed-loop feedback control: the existing piezoelectric nozzle uses an open-loop feedforward control strategy, which can only work reliably under the premise that the viscosity of the ink is stable, but in actual applications, the viscosity of the ink is difficult to maintain stable. Due to the lack of effective ink viscosity identification technology, it is currently impossible to build a closed-loop feedback control.

[0067] To address the aforementioned technical problems, this application provides a method for determining ink viscosity. This method utilizes the self-sensing characteristics of the piezoelectric actuators already inside the piezoelectric printhead to identify ink viscosity, solving the material deposition defects caused by the inability of traditional piezoelectric inkjet technology to adapt to viscosity changes. This method requires no additional sensors, overcoming the difficulty of integrating existing rotational viscometers and micromechanical viscometers into the piezoelectric printhead. Furthermore, this method addresses the limitation of using only open-loop feedforward control strategies in complex process thermal environments, allowing for the construction of closed-loop feedback control strategies, thus overcoming the shortcomings of traditional inkjet technology in adapting to industrial applications. Additionally, this method addresses the issue that existing piezoelectric printheads typically integrate heating modules to reduce ink viscosity by heating, but traditional heating only provides a rough estimate of ink viscosity. This method, through self-sensing measurement, can obtain accurate ink viscosity, and combined with the heating module, enables precise control of ink viscosity.

[0068] Figure 1 A flowchart of an ink viscosity determination method provided according to some embodiments is shown, including S100-S200.

[0069] S100. Detect the structural vibration fluctuation signal of the piezoelectric nozzle, wherein the structural vibration fluctuation signal is used to characterize the structural vibration characteristics of the piezoelectric nozzle.

[0070] Figure 2 An exemplary schematic diagram illustrating the working principle of a piezoelectric nozzle according to some embodiments is shown. Figure 2 As shown, the printhead structure consists of a microchannel 1 and a piezoelectric actuator 2. Under the drive of an external voltage, the piezoelectric actuator (PZT), i.e., the piezoelectric ceramic structure, undergoes corresponding structural deformation as the voltage waveform changes. This structural deformation causes a change in the volume of the microchannel space, thereby generating pressure waves in the ink inside the microchannel and forming droplets at the nozzle. In this process, since viscosity reflects the viscosity of the ink, it will dampen the structural deformation process of the piezoelectric printhead. The greater the ink viscosity, the greater the damping on the structural deformation of the piezoelectric printhead. From the above analysis, it can be seen that by analyzing the strength of the damping, the viscosity of the ink can be estimated. Therefore, in this embodiment, the ink viscosity is determined by analyzing the strength of the damping from the structural vibration characteristics of the piezoelectric printhead.

[0071] In some embodiments, the step of detecting the structural vibration fluctuation signal of the piezoelectric nozzle includes:

[0072] A voltage waveform of a preset frequency is input to a self-sensing measurement circuit to output a structural vibration fluctuation signal. Figure 3A schematic diagram illustrating the principle of a self-sensing measurement circuit according to some embodiments is provided. The self-sensing measurement circuit includes a first branch, a second branch, and a differential amplifier; the first branch includes a piezoelectric actuator corresponding circuit 3 and a first transimpedance operational amplifier 4 connected to the output terminal of the piezoelectric actuator corresponding circuit; the second branch includes a ceramic capacitor 5 and a second transimpedance operational amplifier 6 connected to the output terminal of the ceramic capacitor; the output terminals of the first transimpedance operational amplifier and the second transimpedance operational amplifier are respectively connected to the input terminal of the differential amplifier 7; the ceramic capacitor and the static capacitor of the piezoelectric actuator in the piezoelectric actuator corresponding circuit have the same capacitance value.

[0073] In this embodiment, a self-sensing measurement circuit is used to determine the structural vibration fluctuation signal, which characterizes the structural vibration characteristics of the piezoelectric nozzle. Figure 3 In the middle, the voltage waveform is input to the input terminal of circuit 3 corresponding to the piezoelectric actuator to output current i. sum (t), the current i sum (t) is input to the input terminal of the first transimpedance operational amplifier 4. The voltage waveform is also input to the input terminal of the ceramic capacitor 5 to output current i. m (t), the current i m (t) is input to the input terminal of the second transimpedance operational amplifier 6. The output terminals of the first transimpedance operational amplifier 4 and the second transimpedance operational amplifier 6 are respectively connected to the input terminal of the differential amplifier 7.

[0074] Figure 4 An exemplary circuit diagram corresponding to a piezoelectric actuator according to some embodiments is shown. Figure 4 In the circuit 3 corresponding to the piezoelectric actuator, there are a static capacitor 31 of the piezoelectric actuator connected in parallel and a component 32 corresponding to the charge change caused by the structural deformation of the piezoelectric actuator.

[0075] in,

[0076] In the formula, i sum (t) is the total output current of the piezoelectric actuator, i c (t) is the current generated by the voltage waveform exciting the static capacitor, i q (t) is the current caused by the structural deformation of the piezoelectric actuator (positive piezoelectric effect), C s It is the static capacitance of the piezoelectric actuator, V(t) is the applied voltage waveform, and Q is the static capacitance of the piezoelectric actuator. s (t) is the induced charge generated by the structural deformation of the piezoelectric actuator, d is is the electromechanical coupling coefficient of the piezoelectric actuator (with the physical dimension of [C / m]), and S(t) represents the deformation of the piezoelectric actuator.

[0077] According to the above analysis, the current i q (t) represents the piezoelectric actuator structure deformation rate, from the total current i sum (t) remove i c (t) component, can obtain only represents the structure of the electrical signal characteristics of vibration. By piezoelectric actuator in parallel with a ceramic capacitor C m (no piezoelectric effect), and the voltage waveform is loaded in the input electrode of ceramic capacitor 32, the output electrode is connected to two groups of gain gi transimpedance operational amplifier (TIA), the output current is converted into corresponding voltage signal.

[0078] Referring again to Figure 3 , the piezoelectric actuator output current corresponding to the voltage signal and the voltage signal corresponding to the ceramic capacitor can be expressed as follows:

[0079]

[0080] In the formula, V s (t) is the piezoelectric actuator output current corresponding to the voltage signal, V m (t) is the voltage signal corresponding to the ceramic capacitor; DA is the differential amplifier. In the circuit, adjust the ceramic capacitor C m so that it has the same capacitance value as the static capacitor C s , then the voltage V m (t) and V s (t) equation right side of the first item is equal. On this basis, the voltage V s (t) minus voltage V m (t), can obtain only contains the structure of the structure vibration signal V d (t) characteristics of vibration, namely:

[0081] V d (t) = V s (t) - V m (t) = g i i q (t) (3)

[0082] In the formula, V d (t) represents the piezoelectric nozzle structure vibration fluctuation signal, which contains the ink viscosity identification of the characteristic information, when loading the sine voltage waveform, the piezoelectric nozzle will produce sinusoidal form of structure vibration, and V d (t) is expressed as a cosine form of fluctuating voltage.

[0083] In some embodiments, the step of determining the ink viscosity in the piezoelectric inkjet head according to the structural vibration fluctuation signal of the piezoelectric inkjet head comprises:

[0084] determining a corresponding gain voltage according to the structural vibration wavelength signal;

[0085] determining the ink viscosity in the piezoelectric inkjet head according to the gain voltage.

[0086] In the embodiments of the present application, the ink viscosity will significantly affect the structural vibration characteristics of the piezoelectric inkjet head, and the ink viscosity will cause the fluctuation amplitude of the structural vibration fluctuation signal V d (t), but since V d (t) itself is a fluctuation signal, the amplitude of the fluctuation signal needs to be extracted through circuit design to achieve this, which can be achieved through a gain detection module. Through the gain detection module, a corresponding gain voltage can be determined.

[0087] In some embodiments, the step of determining the gain voltage corresponding to the structural vibration wavelength signal of the piezoelectric inkjet head comprises:

[0088] inputting the structural vibration wavelength signal and the voltage waveform into a gain detection module respectively to output a voltage value corresponding to the gain.

[0089] In the embodiments of the present application, the structural vibration wavelength signal is taken as a self-sensing signal, and the voltage waveform is taken as a reference signal. The amplitude variation of the structural vibration wavelength signal is obtained through the self-sensing signal and the reference signal, and a voltage value corresponding to the gain is output. The voltage value corresponding to the gain can be obtained by dividing the reference signal by the self-sensing signal.

[0090] inputting the voltage value corresponding to the gain into an analog-to-digital conversion module to output a gain voltage.

[0091] In the embodiments of the present application, the analog-to-digital conversion module converts the voltage value corresponding to the gain into a digital quantity, i.e., a gain voltage.

[0092] Specifically, in the embodiments of the present application, a piezoelectric inkjet head structural vibration signal measurement system is designed, Figure 5 An exemplary structural diagram of a piezoelectric inkjet head structural vibration signal measurement system according to some embodiments is shown. In Figure 5In the embodiment, the piezoelectric nozzle structure vibration signal measurement system mainly comprises a main controller, a direct digital frequency synthesis, a self-sensing measurement circuit, a current buffer, a gain detection module and an analog-to-digital conversion module, wherein the main controller is composed of a computer host and an embedded controller. The sweep frequency parameters, voltage amplitude and other command parameters can be sent to the main controller through the USB (Universal Serial Bus), the embedded controller writes the sweep frequency parameters into the direct digital frequency synthesis module to form a voltage waveform with a preset frequency, and the current buffer (for improving the driving capability of the sweep frequency signal) is connected in the subsequent stage. The current buffer output signal is divided into two paths, one of which is connected to the self-sensing measurement circuit to excite the piezoelectric nozzle structure vibration; the other is directly input to the gain detection module as a reference signal; the self-sensing measurement circuit outputs the structure vibration fluctuation signal while driving the piezoelectric nozzle, and inputs it to the gain detection module; the gain detection module obtains the amplitude change of the structure vibration signal by comparing the reference signal and the self-sensing signal, and outputs the voltage value corresponding to the gain; the digital-to-analog conversion module collects the gain signal reflecting the structure vibration amplitude and converts it into a digital quantity, i.e. gain voltage, and the embedded controller sends the gain voltage to the computer host for ink viscosity identification and analysis. Through the above system, the piezoelectric actuator of the piezoelectric nozzle can sense the structure vibration characteristics, which lays a foundation for subsequent viscosity identification by the computer host and is the hardware basis and premise for the ink viscosity determination of the embodiment.

[0093] In some embodiments, the preset frequency is the resonant frequency of the piezoelectric nozzle.

[0094] In the embodiment, the premise of ink viscosity identification is that the ink viscosity will significantly affect the structure vibration characteristics, and the structure vibration characteristics caused by the ink viscosity can be accurately sensed. However, since the deformation amount of the piezoelectric actuator excited by the voltage waveform is usually only tens of nanometers during the operation of the piezoelectric nozzle, and the structure and the fluid interact with each other, the structure has a strong coupling effect on the ink, and the ink has a weak coupling effect on the structure, which makes it difficult to find that the ink viscosity has a very small effect on the piezoelectric nozzle structure vibration characteristics under general conditions in the actual test process. How to improve the sensitivity of the piezoelectric nozzle structure to the ink viscosity is the basis of viscosity identification. In order to achieve this goal, the piezoelectric nozzle structure is made to work in a resonant state to improve its sensitivity to the ink viscosity in the embodiment.

[0095] To this end, the embodiments of the present application first analyze the inherent modal of the piezoelectric nozzle structure by using the simulation model, and calculate the displacement amplitude of the piezoelectric actuator under the trigonometric waveform excitation in a wide frequency range (covering the resonant frequency of the structure), so as to determine the resonant frequency of the piezoelectric nozzle. However, there can be multiple frequencies and vibration modes of the resonant frequency of the piezoelectric nozzle, and the resonant mode that is strong in viscous effect should be selected in combination with the structural characteristics of the piezoelectric nozzle, that is, the resonant vibration mode should be the shear motion of the ink. In the shear motion state, the nozzle structure vibration forms a viscous boundary layer near the flow channel wall. Therefore, considering that the nozzle structure vibration in the resonant state is very sensitive to the external damping, the voltage waveform at the preset frequency of the resonant frequency is used to determine the structure vibration fluctuation signal.

[0096] In addition, the nozzle structure vibration in the resonant state is very sensitive to the external damping, and this conclusion is verified by simulation. Figure 6 An exemplary diagram showing the influence of ink viscosity on the amplitude of the piezoelectric nozzle according to some embodiments is shown. In Figure 6 In the diagram, for inks with different viscosities, the piezoelectric nozzle shows significant signal gain changes near the resonant peak. Based on this finding, the embodiments of the present application propose to detect the change in ink viscosity at the resonant frequency.

[0097] According to the above analysis, to enhance the influence of ink viscosity on the structural vibration characteristics of the piezoelectric nozzle, the piezoelectric nozzle needs to be operated at the resonant frequency, and the resonant frequency of the piezoelectric nozzle needs to be determined. To this end, the embodiments of the present application propose to determine the resonant frequency of the piezoelectric nozzle by adjusting the direct digital frequency synthesis module in combination with the aforementioned piezoelectric nozzle structure vibration signal measurement system. In some embodiments, Figure 7 An exemplary flowchart of another ink viscosity determination method according to some embodiments is shown. The method further includes S300-S800.

[0098] S300, set the sweep frequency parameters, wherein the sweep frequency parameters include the scan start frequency, the end frequency and the scan step;

[0099] S400, determine the excitation voltage waveform corresponding to different frequencies according to the sweep frequency parameters.

[0100] In the embodiments, the scan start frequency, the end frequency and the scan step are preliminarily set in combination with the structural characteristics of the piezoelectric nozzle. The different frequencies are determined between the scan start frequency and the end frequency according to the scan step. The excitation voltage waveform corresponding to the frequency can be generated by using the direct digital frequency synthesis module. The excitation voltage waveform corresponding to different frequencies is used to determine the resonant frequency of the piezoelectric nozzle.

[0101] S500, determine the target gain voltage of the excitation voltage waveform corresponding to different frequencies.

[0102] In this embodiment, the excitation voltage waveform can be first input to the self-perception measurement circuit, and the corresponding target structure vibration fluctuation signal is output and input to the gain detection module. In addition, the excitation voltage waveform is directly input to the gain detection module. The gain detection module outputs the target voltage value corresponding to the gain. The target voltage value corresponding to the gain is input to the analog-to-digital conversion module, and the target gain voltage is output. The above process can refer to the process of obtaining the gain voltage by using the voltage waveform in the foregoing. The data processing methods in the two processes are the same.

[0103] S600, judge whether the amplitude-frequency curve formed by the target gain voltage of the excitation voltage waveform corresponding to the different frequencies exists a resonance peak. For example, refer to any one of the curves in Figure 6 , Figure 6 The curve in any one of the curves in Figure 6 Each amplitude-frequency curve has a resonance peak.

[0104] S700, if the resonance peak exists, the frequency corresponding to the resonance peak is determined as the resonance frequency;

[0105] S800, if the resonance peak does not exist, the step of setting the sweep frequency parameter is re-executed until the resonance frequency is determined. The re-set sweep frequency parameter is different from the historically set sweep frequency parameter.

[0106] In the embodiment of the application, after the resonance frequency of the piezoelectric inkjet head is determined, the piezoelectric inkjet head is made to work at the resonance frequency, and the structure vibration fluctuation signal of the piezoelectric inkjet head is continuously detected, the gain voltage of the amplitude is determined, and the gain voltage is sent to the computer host for viscosity identification.

[0107] S200, according to the structure vibration fluctuation signal, determining the viscosity of the ink in the piezoelectric inkjet head.

[0108] The change of the viscosity of the ink will cause the change of the structure vibration characteristics of the piezoelectric inkjet head, that is, the change of the amplitude of the piezoelectric inkjet head, and finally cause the output of different gain voltages of the piezoelectric inkjet head structure vibration signal measurement system. Considering that the mapping relationship between the gain voltage and the viscosity of the ink has a nonlinear characteristic, Figure 8 An exemplary schematic diagram of a target curve provided according to some embodiments is shown, so that the gain voltage needs to be converted into the viscosity of the ink, and the mapping relationship between the viscosity of the ink and the gain voltage needs to be established. For this purpose, in some embodiments, the step of determining the viscosity of the ink in the piezoelectric inkjet head according to the gain voltage comprises:

[0109] The gain voltage is used to determine the ink viscosity using a mapping relationship; wherein, the method for determining the mapping relationship includes two methods, one is linear interpolation and the other is equation fitting.

[0110] In some embodiments, linear interpolation is used to determine the mapping relationship. Linear interpolation can be understood as approximating the entire nonlinearity as a set of linear intervals. Specifically, the methods for determining the mapping relationship include:

[0111] Determine the preset gain voltage for different preset ink viscosities to form the target curve.

[0112] In this embodiment, a preset ink viscosity and its corresponding preset gain voltage can be determined in advance and plotted as a target curve.

[0113] Determine the maximum and minimum preset gain voltages in the target curve.

[0114] Figure 9 An exemplary schematic diagram of another target curve provided according to some embodiments is shown. Figure 9 In the middle, the maximum preset gain voltage is V d1 The minimum preset gain voltage is V. dN .

[0115] Based on the maximum and minimum preset gain voltages, the target curve is segmented to obtain multiple sub-curves. (See again...) Figure 9 ,exist Figure 9 It includes 5 sub-curves. Each sub-curve can be viewed as a linear interval.

[0116] Determine the preset gain voltage corresponding to the starting point of the sub-curve.

[0117] For example, see again Figure 9 Each of the five sub-curves has a corresponding starting point. From left to right, the preset gain voltage of the starting point of the first sub-curve is Vd1. The preset gain voltage of the starting point of the second sub-curve is Vd2, and so on.

[0118] The conversion coefficient corresponding to the sub-curve is determined by using the preset gain voltage corresponding to the starting point of the sub-curve and the preset ink viscosity on the sub-curve.

[0119] In this embodiment, each sub-curve has a corresponding conversion coefficient. See again... Figure 9 ,exist Figure 9 It includes 5 conversion coefficients, namely [k1,k2,…,k5].

[0120] According to the preset gain voltage corresponding to the starting point of the sub-curve and the conversion coefficient corresponding to the sub-curve, a mapping relationship between the gain voltage and the ink viscosity is determined.

[0121] The mapping relationship between the gain voltage and the ink viscosity is described by the following equation.

[0122] μ=V di -k i V d (t), V di+1 ≤V d (t) < V di (4)

[0123] In the equation, k i is a linear conversion coefficient of a linear segment i (i.e., the i-th sub-curve), V d (t) is a measured gain voltage located in the voltage interval [V di , V di+1 ], dimensionless data, and μ is the converted ink viscosity. Therefore, according to the above equation, the measured gain voltage can be converted into the corresponding ink viscosity, and the more the number of linear segments, the higher the conversion accuracy of the gain voltage to the ink viscosity.

[0124] In the embodiment, when converting the gain voltage into the ink viscosity, the linear interval in which the gain voltage is located is first determined according to the measured gain voltage, i.e., which sub-curve it belongs to, and the corresponding conversion coefficient is determined accordingly, and finally the conversion coefficient is used to convert the gain voltage into the ink viscosity.

[0125] In some embodiments, the mapping relationship is determined by equation fitting. The conversion accuracy of the linear interpolation method depends on the number of linear segments, and the error is the largest in the middle position of the linear segment region, because the linear interpolation ignores the high-order mapping relationship in the local area. The equation fitting method can overcome the defects of the linear interpolation method, a group of gain voltage data is obtained by using the known viscosity ink sample as sample data, and the undetermined coefficients of the equation are determined by parameter regression, and the mathematical form of the equation can be selected by analyzing the sample data, such as a monomial equation, a proportional equation, etc.

[0126] Specifically, the mapping relationship is determined by equation fitting. The determination method of the mapping relationship includes:

[0127] The preset gain voltage under different preset ink viscosities is determined to form a target curve.

[0128] In the embodiment, Figure 10An exemplary schematic diagram of another target curve provided according to some embodiments is shown. This step is the same as the step described above in determining the preset gain voltage at different preset ink viscosities to form the target curve using the linear interpolation method to determine the mapping relationship, and will not be repeated here.

[0129] The target curve is fitted to obtain the mapping relationship between gain voltage and ink viscosity.

[0130] The following formula can represent the mapping relationship between gain voltage and ink viscosity:

[0131] μ = f fit (V d (t))(5)

[0132] In the formula, f fit The fitted function is obtained through parametric regression. The relationship between ink viscosity and gain voltage after fitting is as follows: Figure 10 As shown, since the fitting process is a higher-order approximation, under the premise of selecting a suitable fitting equation, the mapping between the fitted gain voltage and ink viscosity is more accurate, and the corresponding ink viscosity identification is also more precise. In the embodiments of this application, a high-precision conversion relationship between gain voltage and ink viscosity can be obtained through data fitting.

[0133] In this embodiment, precise measurement of the ink viscosity inside the piezoelectric printhead can be achieved, which is key to constructing a closed-loop feedback material ejection process and a prerequisite for precise control of the ink viscosity within the nozzle. The method proposed in this embodiment is of significant value for further improving the performance of piezoelectric inkjet printing technology.

[0134] This application provides a method for determining ink viscosity. This method utilizes the discovery that ink viscosity significantly affects the structural vibration characteristics of a piezoelectric printhead. By using structural vibration fluctuation signals, which characterize the structural vibration characteristics of a piezoelectric printhead, the ink viscosity in the piezoelectric printhead is determined. This achieves self-sensing measurement of the internal ink viscosity by the piezoelectric printhead, providing a feasible approach for closed-loop feedback control of jet performance and precise control of ink viscosity. This can promote the reliability of piezoelectric inkjet printing technology in emerging applications such as printed electronics and sensors.

[0135] To further illustrate the implementation process of this application, the following examples are provided using the MJ-AL-80 single-nozzle piezoelectric nozzle.

[0136] First, by testing the static capacitance of the piezoelectric nozzle, the capacitance is about 1.5nF, by welding a suitable matching capacitor to the self-sensing measurement circuit, the self-sensing measurement circuit can accurately measure the structural vibration fluctuation signal of the piezoelectric nozzle. Simulation found that the resonance frequency of the MJ-AL-80 piezoelectric nozzle is about 113kHz, considering the difference between the simulation model and the actual nozzle structure, the actual resonance frequency of the piezoelectric nozzle is scanned in the range of 50kHz-250kHz, and the results are shown in Figure 11 , which shows that there is a significant resonance peak near 137.1kHz.

[0137] Secondly, on the basis of obtaining the actual resonance peak of the piezoelectric nozzle, the resonance frequency of the piezoelectric nozzle is determined as 137.1kHz, the direct digital frequency synthesis module is controlled to output the voltage waveform at the resonance frequency to excite the piezoelectric nozzle, and the structural amplitude gain voltage of the piezoelectric nozzle is continuously recorded.

[0138] In order to verify that the gain voltage can accurately reflect the influence of the ink viscosity, the piezoelectric nozzle is respectively placed on the heating constant temperature substrate at 45℃, 50℃ and 55℃, and the change of the gain voltage is recorded, and the results are shown in Figure 12 . The results show that the higher the substrate temperature, the lower the ink viscosity, and the greater the structural amplitude gain voltage, which is completely consistent with the law that the ink viscosity is affected by the temperature, proving the effectiveness of the method proposed in the embodiment of the application in ink viscosity sensing.

[0139] Thirdly, the equation fitting method is used for ink viscosity identification. In the fitting of experimental data, it is found that the following mathematical relationship can well fit the experimental data:

[0140]

[0141] In the formula, V d is the gain voltage output by the analog-to-digital conversion module, and a and b are undetermined coefficients. Through data fitting, the conversion relationship from the gain voltage to the ink viscosity can be obtained. For the MJ-AL-80 piezoelectric nozzle, the fitted coefficients a and b are 3.8765 and 0.4131 respectively, and the fitting effect is shown in Figure 13 , which shows that the fitted equation is well matched with the experimental data.

[0142] Finally, four standard reagents (aniline, photocurable resin, glycerol-water mixture, and ethylene glycol) are used to analyze the stability of the method proposed in the embodiment of the application. First, the viscosity of the four reagents is measured by a rotary viscometer, which is 3.76, 8.41, 13.31 and 18.54mPa·s respectively. The four reagents are added into the piezoelectric nozzle respectively, and 10 groups of viscosity measurement data are recorded for each reagent. The viscosity identification results of the four reagents are shown in Figure 14As shown, the average values of the identified viscosities are 3.93, 8.09, 13.44, and 18.74 mPa·s, respectively, and the relative errors with respect to the measurement results of the viscometer are 4.5%, 3.8%, 0.9%, and 1.1%, respectively. The fluctuation ranges of the 10 groups of measurement data are 0.34, 0.38, 0.23, and 0.29 mPa·s, respectively. Since the jettable viscosity of the piezoelectric nozzle is usually less than 20 mPa·s, the viscosities of the four reagents basically cover the jettable viscosity range, which means that the method proposed in the embodiment has an error of less than 4.5% in viscosity identification, and the fluctuation range of the measured viscosity is less than 0.4 mPa·s, proving that the method has good viscosity identification accuracy and can meet the demand for jet performance regulation of inkjet printing, which is of great significance for improving the stability and reliability of inkjet-based additive manufacturing technology.

[0143] Further, as an implementation of the method described above Figure 1 As an implementation of the method shown, the embodiment of the present application provides an ink viscosity determination device, which comprises: Figure 15

[0144] a detection unit configured to detect a structural vibration fluctuation signal of the piezoelectric nozzle, the structural vibration fluctuation signal being used to represent the structural vibration characteristics of the piezoelectric nozzle;

[0145] a determination unit configured to determine the ink viscosity in the piezoelectric nozzle according to the structural vibration fluctuation signal.

[0146] According to an embodiment of the present application, a storage medium is provided, which stores at least one executable instruction, and the computer executable instruction can execute the ink viscosity determination method in any of the above method embodiments.

[0147] According to an embodiment of the present application, a printer is provided, which comprises a piezoelectric nozzle, a processor, a memory, a communication interface, and a communication bus, and the processor, the memory, and the communication interface complete communication with each other through the communication bus.

[0148] The memory is used to store at least one executable instruction, and the executable instruction causes the processor to execute the ink viscosity determination method.

[0149] Figure 16 A structural schematic diagram of a terminal according to an embodiment of the present application is shown, and the specific implementation of the terminal is not limited in the specific embodiments of the present application.

[0150] As shown in Figure 16 The terminal can comprise a processor 402, a communication interface 404, a memory 406, and a communication bus 408.​

[0151] The processor 402, the communication interface 404, and the memory 406 communicate with each other through the communication bus 408.

[0152] The communication interface 404 is configured to communicate with network elements such as clients or other servers.

[0153] The processor 402 is configured to execute the program 410, and can particularly execute the related steps in the power line fault monitoring method embodiments.

[0154] Specifically, the program 410 can include program codes including computer operation instructions.

[0155] The processor 402 can be a central processing unit (CPU), or an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present application. The one or more processors included in the terminal can be processors of the same type, such as one or more CPUs; or can be processors of different types, such as one or more CPUs and one or more ASICs.

[0156] The memory 406 is configured to store the program 410. The memory 406 can include a high-speed RAM memory, and can further include a non-volatile memory such as at least one disk memory.

[0157] Obviously, those skilled in the art should understand that the modules or steps of the present application described above can be implemented by general computing devices, and can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, and alternatively, they can be implemented by program codes executable by computing devices, so that they can be stored in storage devices and executed by computing devices, and in some cases, the steps shown or described can be executed in different orders, or they can be manufactured into individual integrated circuit modules, or multiple modules or steps can be manufactured into a single integrated circuit module. Thus, the present application is not limited to any particular combination of hardware and software.

[0158] The above only describes preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for determining ink viscosity, characterized in that, include: The structural vibration fluctuation signal of the piezoelectric nozzle is detected, and the structural vibration fluctuation signal is used to characterize the structural vibration characteristics of the piezoelectric nozzle. The viscosity of the ink in the piezoelectric printhead is determined based on the structural vibration wave signal. The step of detecting the structural vibration fluctuation signal of the piezoelectric nozzle includes: inputting a voltage waveform of a preset frequency into a self-sensing measurement circuit to output a structural vibration fluctuation signal; wherein the self-sensing measurement circuit includes a first branch, a second branch, and a differential amplifier; the first branch includes a piezoelectric actuator corresponding circuit and a first transimpedance operational amplifier connected to the output terminal of the piezoelectric actuator corresponding circuit; the second branch includes a ceramic capacitor and a second transimpedance operational amplifier connected to the output terminal of the ceramic capacitor; the output terminals of the first transimpedance operational amplifier and the second transimpedance operational amplifier are respectively connected to the input terminal of the differential amplifier; the ceramic capacitor and the static capacitor of the piezoelectric actuator in the piezoelectric actuator corresponding circuit have the same capacitance value; the piezoelectric actuator corresponding circuit includes a parallel static capacitor of the piezoelectric actuator and a component corresponding to the charge change generated by the structural deformation of the piezoelectric actuator; The voltage signal corresponding to the output current of the piezoelectric actuator and the voltage signal corresponding to the ceramic capacitor are expressed by the following formula: ； In the formula, It is the voltage signal corresponding to the output current of the piezoelectric actuator. This is the voltage signal corresponding to the ceramic capacitor; in the circuit, adjusting the ceramic capacitor... Make it similar to the static capacitor With the same capacitance value, the voltage and The first terms on the right side of the equation are equal; ； In the formula, This represents the structural vibration fluctuation signal of the piezoelectric nozzle; The preset frequency is the resonant frequency of the piezoelectric nozzle; The method further includes: setting sweep parameters, wherein the sweep parameters include a scan start frequency, an end frequency, and a scan step size; determining the excitation voltage waveform corresponding to different frequencies based on the sweep parameters; determining the target gain voltage of the excitation voltage waveform corresponding to different frequencies; judging whether the amplitude-frequency curve formed by the target gain voltage of the excitation voltage waveform corresponding to different frequencies has a resonance peak; if a resonance peak exists, the frequency corresponding to the resonance peak is determined as the resonance frequency; if no resonance peak exists, the step of setting the sweep parameters is repeated until the resonance frequency is determined, and the re-set sweep parameters are different from the previously set sweep parameters; The step of determining the ink viscosity in the piezoelectric printhead based on the structural vibration fluctuation signal of the piezoelectric printhead includes: determining the corresponding gain voltage based on the structural vibration fluctuation signal; and determining the ink viscosity in the piezoelectric printhead based on the gain voltage. The step of determining the ink viscosity in the piezoelectric printhead based on the gain voltage includes: determining the ink viscosity by using a mapping relationship with the gain voltage.

2. The method according to claim 1, characterized in that, The step of determining the corresponding gain voltage based on the structural vibration wave signal of the piezoelectric nozzle includes: inputting the structural vibration wave signal and the voltage waveform into the gain detection module respectively to output the voltage value corresponding to the gain; and inputting the voltage value corresponding to the gain into the analog-to-digital conversion module to output the gain voltage.

3. The method according to claim 1, characterized in that, The method for determining the mapping relationship includes: Determine the preset gain voltage for different preset ink viscosities to form the target curve; Determine the maximum and minimum preset gain voltages in the target curve; The target curve is divided into multiple sub-curves based on the maximum and minimum preset gain voltages. Determine the preset gain voltage corresponding to the starting point of the sub-curve; Using the preset gain voltage corresponding to the starting point of the sub-curve and the preset ink viscosity on the sub-curve, the conversion coefficient corresponding to the sub-curve is determined; The mapping relationship between gain voltage and ink viscosity is determined based on the preset gain voltage corresponding to the starting point of the sub-curve and the conversion coefficient corresponding to the sub-curve.

4. The method according to claim 1, characterized in that, The step of determining the ink viscosity in the piezoelectric printhead based on the gain voltage includes: The ink viscosity is determined using a mapping relationship based on the gain voltage; wherein the method for determining the mapping relationship includes: Determine the preset gain voltage for different preset ink viscosities to form the target curve; The target curve is fitted to obtain the mapping relationship between gain voltage and ink viscosity.

5. An ink viscosity determining device, characterized in that, The apparatus for implementing the method according to any one of claims 1-4, the apparatus comprising: A detection unit is used to detect the structural vibration fluctuation signal of the piezoelectric nozzle, which characterizes the structural vibration characteristics of the piezoelectric nozzle. Specifically, the detection unit performs the following: inputting a voltage waveform of a preset frequency to a self-sensing measurement circuit to output the structural vibration fluctuation signal; wherein, the self-sensing measurement circuit includes a first branch, a second branch, and a differential amplifier; the first branch includes a piezoelectric actuator corresponding circuit and a first transimpedance operational amplifier connected to the output terminal of the piezoelectric actuator corresponding circuit; the second branch includes a ceramic capacitor and a second transimpedance operational amplifier connected to the output terminal of the ceramic capacitor; the output terminals of the first transimpedance operational amplifier and the second transimpedance operational amplifier are respectively connected to the input terminal of the differential amplifier; the ceramic capacitor and the static capacitor of the piezoelectric actuator in the piezoelectric actuator corresponding circuit have the same capacitance value; the piezoelectric actuator corresponding circuit includes a parallel connection of the piezoelectric actuator's static capacitor and a component corresponding to the charge change caused by structural deformation of the piezoelectric actuator; The determining unit is used to determine the ink viscosity in the piezoelectric printhead based on the structural vibration fluctuation signal.

6. A printer, characterized in that, include: The device includes a piezoelectric nozzle, a processor, a memory, a communication interface, and a communication bus. The processor, the memory, and the communication interface communicate with each other through the communication bus. The memory is used to store at least one executable instruction that causes the processor to perform the ink viscosity determination method as described in any one of claims 1-4.

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