Voltage waveform adjustment device, processing method for voltage waveform adjustment device, and program

Abstract

Even when there are significant individual differences between nozzles, the voltage waveform can be adjusted quickly for each nozzle. [Solution] The voltage waveform adjusting device is a voltage waveform adjusting device for adjusting the voltage waveform used to drive a first nozzle and a second nozzle that discharge liquid, and comprises: an acquisition unit that acquires a displacement amount representing the amount of deviation in discharge characteristics between the first nozzle and the second nozzle; a storage unit that stores a target discharge characteristic which is the target discharge characteristic of the droplet discharged from the second nozzle and a first nozzle model which is a model for estimating the discharge characteristic of the droplet discharged when a voltage waveform is applied to the first nozzle; and a determination unit that uses the stored first nozzle model to determine the voltage waveform to be applied to the second nozzle based on the acquired displacement amount and the stored target discharge characteristic.

Description

[Technical Field]

[0001] The present invention relates to a voltage waveform adjustment device, a processing method for the voltage waveform adjustment device, and a program. [Background technology]

[0002] There are inkjet printers called piezoelectric inkjet printers that use piezoelectric elements (piezoelectric elements) that deform when voltage is applied to eject liquid droplets. With the piezoelectric method, it is possible to eject liquid droplets with desired ejection characteristics (e.g., ejection speed and amount) by arbitrarily changing the shape of the voltage waveform (drive waveform) applied to the piezoelectric element. By configuring a liquid ejection head with multiple nozzles, each with its own piezoelectric element, and applying an individual voltage waveform to each piezoelectric element, high-precision ejection control becomes possible.

[0003] Non-patent document 1 discloses details of a method by which droplets are ejected in a piezoelectric system.

[0004] Patent Document 1 discloses a method for determining candidate voltage waveforms with desired discharge characteristics using a trained model that takes a voltage waveform as input and outputs discharge characteristics. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-176204 [Non-patent literature]

[0006] [Non-Patent Document 1] Inkjet, edited by the Image Science Society of Japan, supervised by Masahiko Fujii, Tokyo Denki University Press, 2nd edition published July 20, 2018. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The method described in Patent Document 1 has the problem that a model must be pre-trained to output discharge characteristics (discharge speed, discharge volume, etc.) using a voltage waveform as input. If there are significant individual differences between nozzles due to manufacturing errors, etc., it becomes necessary to train a model for each nozzle, but since training a model requires a large amount of training data, adjustment may take a long time.

[0008] Therefore, the present invention aims to enable high-speed voltage waveform adjustment for each nozzle, even when there are significant individual differences between nozzles. [Means for solving the problem]

[0009] The voltage waveform adjusting device is a voltage waveform adjusting device for adjusting the voltage waveform used to drive a first nozzle and a second nozzle that discharge liquid, and comprises: an acquisition unit that acquires a displacement amount representing the amount of deviation in discharge characteristics between the first nozzle and the second nozzle; a storage unit that stores a target discharge characteristic which is the target discharge characteristic of the droplet discharged from the second nozzle and a first nozzle model which is a model for estimating the discharge characteristic of the droplet discharged when a voltage waveform is applied to the first nozzle; and a determination unit that uses the stored first nozzle model to determine the voltage waveform to be applied to the second nozzle based on the acquired displacement amount and the stored target discharge characteristic. [Effects of the Invention]

[0010] According to the present invention, even when there are significant individual differences between nozzles, it is possible to adjust the voltage waveform for each nozzle at high speed. [Brief explanation of the drawing]

[0011] [Figure 1] This figure shows an example of the hardware configuration of the voltage waveform adjustment device and liquid dispensing device in the first embodiment. [Figure 2] This figure shows an example of the functional configuration of the voltage waveform adjustment device in the first embodiment. [Figure 3]This figure shows an example of a voltage waveform in the first embodiment. [Figure 4] This figure shows an example of a neural network in the first embodiment. [Figure 5] This flowchart shows the processing flow by the voltage waveform adjustment device 10 in the first embodiment. [Figure 6] This figure shows an example of a voltage waveform that can be discharged normally in the first embodiment. [Figure 7] This figure shows an example of a display by the voltage waveform adjustment device in the first embodiment. [Figure 8] This figure shows an example of the hardware configuration of the voltage waveform adjustment device and liquid discharge device in the second embodiment. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the configurations shown in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

[0013] <First Embodiment> In the first embodiment, a method for rapidly adjusting the voltage waveform for each nozzle, even when there are significant individual differences between nozzles, will be described.

[0014] Figure 1(a) shows an example of the hardware configuration of a voltage waveform adjustment system 30 according to the first embodiment. The voltage waveform adjustment system 30 includes a voltage waveform adjustment device 10 and a liquid dispensing device 20.

[0015] The voltage waveform adjustment device 10 has a hardware configuration that includes a CPU 11, ROM 12, RAM 13, storage device 14, input device 15, communication I / F 16, display device 17, and system bus 19.

[0016] The central processing unit (CPU) 11 uses RAM 13 as work memory to read and execute the OS and other programs stored in ROM 12 and storage device 14, and controls each component connected to the system bus 19 to perform calculations and logical decisions for various processes. The processing performed by the CPU 11 includes the information processing of this embodiment.

[0017] The storage device 14 is a hard disk drive or an external storage device, and stores programs and various data related to the information processing in this embodiment.

[0018] The input device 15 includes an imaging device such as a camera, and input devices such as buttons, a keyboard, and a touch panel for inputting user instructions.

[0019] The storage device 14 is connected to the system bus 19 via an interface such as SATA, and the input device 15 is connected via a serial bus such as USB, but details of these connections are omitted.

[0020] The communication interface 16 communicates with the liquid dispensing device 20, which will be described later. The display device 17 is a display.

[0021] The liquid dispensing device 20 has a hardware configuration that includes a communication I / F 21, a dispensing control device 22, a drive device 24, a liquid dispensing head 23, and a measuring device 25.

[0022] The communication interface 21 communicates with the voltage waveform adjustment device 10, receiving dispensing instructions from the voltage waveform adjustment device 10 and transmitting measurement results of the liquid dispensed to the voltage waveform adjustment device 10.

[0023] The discharge control device 22, in accordance with the discharge instruction from the voltage waveform adjustment device 10 received via the communication I / F 21, issues a discharge instruction to the drive device 24 and simultaneously issues a measurement instruction to the measuring device 25. By coordinating the operation of the drive device 24 and the measuring device 25, the discharge control device 22 causes the measuring device 25 to measure the discharge characteristics (discharge speed, discharge volume, etc.) of the droplets discharged from the liquid discharge head 23.

[0024] The liquid dispensing head 23 has multiple nozzles for dispensing liquid droplets. Each nozzle is numbered for easy identification. Figure 1(b) illustrates the details of the liquid dispensing head 23.

[0025] Figure 1(b) is a schematic diagram of one of the multiple nozzles of the liquid discharge head 23. The individual electrodes 31 are connected to a drive unit 24, which will be described later, and a voltage waveform is applied from the drive unit 24. One individual electrode 31 is provided for each nozzle.

[0026] The piezoelectric element 32 is an element made of a piezoelectric material, and it deforms (piezoelectric strain) in response to the voltage applied to the individual electrodes 31.

[0027] The diaphragm 33 vibrates in response to the deformation of the piezoelectric element 32, thereby changing the volume of the pressure chamber 36. By applying an appropriate voltage waveform to the individual electrodes 31, the ink vibrates, and as a result, droplets 38 are ejected from the opening of the nozzle 37.

[0028] The liquid chamber 34 is a space filled with ink and supplies ink to the pressure chamber 36 through individual supply channels 35. The liquid chamber 34 may be connected to multiple pressure chambers 36 through multiple individual supply channels 35.

[0029] Returning to the explanation of Figure 1(a), the drive unit 24 applies a voltage waveform (drive signal) to the individual electrodes 31 of the liquid discharge head 23 in accordance with the discharge instruction from the discharge control device 22. The drive unit 24 can apply independent voltage waveforms to multiple individual electrodes 31 of the liquid discharge head 23. The discharge instruction includes the nozzle number and information on the voltage waveform to be applied to the individual electrodes 31 of that nozzle, and the drive unit 24 applies the specified voltage waveform to the individual electrodes 31 of the specified nozzle in accordance with the discharge instruction.

[0030] To the extent that there is no misunderstanding, the process of applying a voltage waveform to an individual electrode 31 of a nozzle will be simply referred to as "applying a voltage waveform to the nozzle."

[0031] The measuring device 25 images the droplets in flight being ejected from the nozzle of the liquid discharge head 23 and measures the ejection characteristics of those droplets. Droplet measurement can be performed, for example, by photographing the droplets from the side with a camera as they are ejected from the nozzle and fly towards an unillustrated target surface. The measuring device 25 continuously photographs the droplet at time T and the same droplet at time T+ΔT. The size of the droplet in the captured images is obtained through image processing to determine the droplet ejection volume. Furthermore, the droplet ejection velocity is obtained by dividing the distance the droplet traveled during ΔT by ΔT. The measuring device 25 is pre-adjusted to measure droplets from any nozzle of the liquid discharge head 23.

[0032] The following describes an example of the functional configuration of the voltage waveform adjustment device 10 using Figure 2. The functional configuration in Figure 2 is realized by the CPU 11 executing a program.

[0033] The voltage waveform adjustment device 10 includes an input unit 101, a learning unit 102, a storage unit 103, a determination unit 104, a discharge unit 105, a discharge measurement unit 106, and an output unit 107.

[0034] The input unit 101 acquires the nozzle number of the nozzle whose voltage waveform should be adjusted (the nozzle to be adjusted) and the discharge characteristics to be achieved for each nozzle to be adjusted (the target discharge characteristics). In this embodiment, the discharge characteristics refer to the discharge volume and discharge velocity of the droplets discharged from the nozzle. Therefore, the target discharge characteristics consist of the target discharge volume and the target discharge velocity. The discharge volume means the volume of the droplet, and the unit usually used is pl (picoliters). The discharge velocity means the flight velocity of the droplet, and the unit usually used is m / s. The target discharge characteristics may be the same value for all nozzles, or they may be different values ​​for each nozzle.

[0035] Discharge characteristics are not limited to these and may include values ​​such as droplet radius, droplet ejection angle, and droplet sphericity.

[0036] The acquired information on the nozzle to be adjusted and the target discharge characteristics is sent to the storage unit 103 and stored in the storage unit 103.

[0037] The learning unit 102 acquires training data consisting of pairs of voltage waveforms and discharge characteristics. The learning unit 102 also learns a model that takes a voltage waveform as input and outputs discharge characteristics.

[0038] Unipolar and bipolar types have been proposed as shapes for the voltage waveform applied to piezoelectric elements. Figure 3 shows an example of a bipolar voltage waveform.

[0039] The voltage waveform in Figure 3 shows the voltage transitioning sequentially from v1, v2, v3, v1. Times t1, t3, and t5 represent the time during which the voltages v1, v2, and v3 are maintained, respectively. Time t2 represents the time it takes for the voltage to transition from v1 to v2. Time t4 represents the time it takes for the voltage to transition from v2 to v3. Time t6 represents the time it takes for the voltage to transition from v3 to v1.

[0040] The shape of a bipolar voltage waveform is determined by providing nine voltage waveform parameters v1, v2, v3, t1, t2, t3, t4, t5, and t6. Generally, the shape of a voltage waveform can be determined by providing any number of voltage waveform parameters, not just for bipolar waveforms. Hereafter, the voltage waveform shape will be assumed to be bipolar, but the shape of the voltage waveform is not limited to this.

[0041] To the best of our knowledge, unless otherwise misunderstood, the column vector formed by arranging the voltage waveform parameters (here, v1, v2, v3, t1, t2, t3, t4, t5, t6) will simply be referred to as the voltage waveform, and the symbol 'w' will be used to represent it.

[0042] The learning unit 102 applies an arbitrary supervised learning method to learn a model that predicts discharge characteristics from voltage waveforms. Hereinafter, the discharge volume prediction model that predicts the amount of droplet discharged will be denoted as F(w), and the discharge velocity prediction model that predicts the discharge velocity of droplets will be denoted as G(w).

[0043] Here, we will explain the case of learning a quadratic polynomial model as an example.

[0044] In the following, of the nine voltage waveform parameters, only a few parameters that particularly affect the droplet discharge characteristics will be made variable, while the remaining parameters will be fixed to predetermined values. Specifically, (v2, t3) will be made variable, and the remaining parameters will be fixed to predetermined values. In this case, the model F(w) that predicts the droplet discharge amount can be expressed, for example, by the following equation.

[0045] F(w) = a·v² 2 +b·t3 2 +c·v2·t3+d·v2+e·t3+f

[0046] Here, a, b, c, d, e, and f are learnable parameters. A quadratic polynomial model G(w) that predicts the droplet discharge velocity can be expressed similarly.

[0047] This quadratic polynomial is just one example. For instance, one of the nine voltage waveform parameters could be made variable, such as (v2, t2), instead of the previously mentioned (v2, t3). The number of terms could also be changed depending on the increase or decrease in the number of variable parameters. Furthermore, terms known to have a low contribution could be removed.

[0048] Next, the learnable parameters a, b, c, d, e, and f are learned from the previously collected pairs of voltage waveforms and discharge characteristics. Parameter learning can be performed, for example, by calculating the parameters that minimize the sum of the squared errors between the model's output and discharge characteristics using the least squares method. The parameter learning method is not limited to this, and methods such as ridge regression, which prevent parameter overfitting by adding a regularization term to the least squares method, may also be used.

[0049] The model parameters learned by the learning unit 102 are sent to the storage unit 103 and stored there.

[0050] The above describes the case where a quadratic polynomial is used as the model. The model is not limited to this, and any model such as neural networks or decision trees can be applied. As an example, an example of a neural network is shown in Figure 4. Neural network 400 has one hidden layer. The input layer receives variable voltage waveform parameters (v2, t3 in this case), and the output layer outputs discharge characteristics (discharge amount and discharge rate in this case). The parameters of neural network 400 (weights and biases of each node) can be learned using known methods such as backpropagation, using pairs of voltage waveforms and discharge characteristics collected in advance.

[0051] Furthermore, while the shape of the voltage waveform is determined by providing an arbitrary number of voltage waveform parameters (9 in the example above), the method of representing the voltage waveform is not limited to this. For example, a sufficiently small time interval T may be defined, and the time-series values ​​of the voltage at each of the times 0, T, 2T, 3T, 4T, ..., MT may be used as the voltage waveform. Here, M is a positive number sufficient to cover the entire length of the voltage waveform. When representing the shape of the voltage waveform in time-series format, a model such as an RNN (Recurrent Neural Network), typified by Long Short-Term Memory (LSTM), may be used.

[0052] The memory unit 103 stores the nozzles whose voltage waveforms should be adjusted (target nozzles) and the discharge characteristics to be achieved for each target nozzle, which are acquired by the input unit 101. The memory unit 103 also stores the parameters of the model learned by the learning unit 102. Furthermore, the memory unit 103 stores the voltage waveform adjustment results for each target nozzle (a set of nozzle number, number of adjustments, voltage waveform, discharge result, and determination result of whether or not the discharge criteria were met).

[0053] The determination unit 104 receives the nozzle number and target discharge characteristics of the nozzles to be adjusted from the input unit 101, and determines the voltage waveform to be applied to each nozzle to be adjusted so that each nozzle achieves the target discharge characteristics. The determined voltage waveform is sent to the discharge unit 105. Details of the process will be described later.

[0054] The dispensing unit 105 receives the voltage waveform and the nozzle number of the target nozzle from the learning unit 102 and the determination unit 104, and applies the above voltage waveform to the target nozzle to dispense droplets from the target nozzle. This process is achieved by requesting the liquid dispensing device 20 from the voltage waveform adjustment device 10.

[0055] The discharge measurement unit 106 measures the discharge characteristics of the droplets discharged from the target nozzle by the discharge unit 105 and obtains the results. This process is achieved by requesting the liquid discharge device 20 from the voltage waveform adjustment device 10.

[0056] The output unit 107 displays the voltage waveform adjustment results for each nozzle to be adjusted on a display device 17, such as a display. The adjustment results include, for example, whether the voltage waveform adjustment was successful for each nozzle to be adjusted, the value of the discharge characteristics obtained as a result of the voltage waveform adjustment, and the amount (displacement) of how much nozzle A is deviating from the reference nozzle.

[0057] An example of the voltage waveform adjustment process flow of the voltage waveform adjustment device 10 according to this embodiment will be explained with reference to Figure 5. The processing method of the voltage waveform adjustment device 10 will be explained below. The voltage waveform adjustment device 10 adjusts the voltage waveform used to drive the reference nozzle that discharges liquid and the nozzle to be adjusted.

[0058] In step S501, the input unit 101 acquires the nozzle number of the nozzle whose voltage waveform should be adjusted (the nozzle to be adjusted) and the discharge characteristics to be achieved at each nozzle to be adjusted (the target discharge characteristics). For simplicity, it is assumed that the same target discharge characteristics are given to all nozzles to be adjusted. The given target discharge volume is Vd target [pl], target discharge rate is V target Let's use [m / s].

[0059] The acquired information on the nozzle to be adjusted and the target discharge characteristics is sent to the storage unit 103 and stored in the storage unit 103.

[0060] In step S502, the learning unit 102 acquires learning data consisting of a pair of voltage waveform and discharge characteristics. An example of how to acquire the learning data is described below.

[0061] First, the learning unit 102 determines the nozzle from which to collect training data. This nozzle will be referred to as the reference nozzle below. It is desirable to select the reference nozzle from among nozzles that have as average discharge characteristics as possible. Here, we will select one nozzle from the middle of the many nozzles to be arranged as the reference nozzle, but the selection method is not limited to this. For example, preliminary data may be collected from multiple reference nozzle candidates, and the nozzle with the most average trend may be selected as the reference nozzle. Alternatively, multiple nozzles may be selected as reference nozzles, and the average value of the discharge characteristics of the multiple nozzles may be used as a representative.

[0062] Next, the learning unit 102 determines which of the voltage waveform parameters will be variable and their range of motion. For example, v2 and t3 are set as variable parameters from the voltage waveform explained in Figure 3. The range of motion for v2 is set as [v2min, v2max], and the range of motion for t3 is set as [t3min, t3max]. In this case, it is desirable to determine the range of motion so as not to deviate from the range of voltage waveforms that can be discharged normally. Here, normal discharge means that there are no phenomena such as satellites (a phenomenon in which small droplets are generated in addition to the main droplet) or mist (a phenomenon in which many very small droplets are generated), or non-discharge (a droplet is not discharged), and ideally, one droplet is discharged.

[0063] Next, the learning unit 102 varies the variable parameters of the voltage waveform to obtain a list of voltage waveforms for training data collection. For example, by determining v2 using U(v2min,v2max) and t3 using U(t3min,t3max), one voltage waveform can be generated. Here, U(a,b) is a function that returns one value randomly sampled from the interval [a,b] according to a uniform distribution. By repeating this N times, a list of voltage waveforms of length N can be obtained.

[0064] The method for generating a list of voltage waveforms is not limited to this. For example, v2 takes one of K discrete values [v 21 , v 22 , …, v 2K , and t3 takes one of L discrete values [t 31 , t 32 , …, t 3L . In this case, the number of possible voltage waveforms is K × L. By randomly selecting N from the K × L voltage waveforms, a voltage waveform list of length N can be obtained. If the number of possible voltage waveforms is sufficiently small, N = K × L may be used.

[0065] Furthermore, it is also conceivable that the details of the range of voltage waveforms that can be normally ejected are known in advance. Figure 6 shows an example of a voltage waveform that can be normally ejected. In this graph, the horizontal axis is t3 and the vertical axis is v2, and the voltage waveforms that can be normally ejected are represented by circles. By randomly selecting N from the voltage waveforms that can be normally ejected, a voltage waveform list of length N can be obtained.

[0066] Next, the learning unit 102 passes the nozzle number of the reference nozzle and each voltage waveform included in the list of voltage waveforms to the ejection unit 105. The ejection unit 105 sequentially applies the above voltage waveforms to the piezoelectric element of the reference nozzle to eject droplets. The ejection measurement unit 106 sequentially measures the ejected droplets. Through this process, learning data consisting of a combination of voltage waveforms and ejection characteristics can be obtained.

[0067] In step S503, the learning unit 102 learns a model that outputs ejection characteristics with a voltage waveform as an input. As described above, by applying any supervised learning method, a droplet ejection amount prediction model F(w) and a droplet ejection speed prediction model G(w) are obtained. The learned model parameters of F(w) and G(w) are sent to the storage unit 103 and held by the storage unit 103. Since these models are learned using data collected by the reference nozzle, they are hereinafter referred to as reference models.

[0068] Steps S505 to S508, sandwiched between steps S504 and S509, are voltage waveform adjustment processes performed for each nozzle to be adjusted. For example, if the nozzles to be adjusted are arranged as nozzle A, nozzle B, etc., the process from steps S505 to S508 is repeated 1st, 2nd, ... for nozzle A until the voltage waveform adjustment is successful. If the voltage waveform adjustment is successful at any point, the process from steps S505 to S508 is repeated 1st, 2nd, ... for nozzle B until the voltage waveform adjustment is successful. The same applies to subsequent steps. In the following section, we will explain the details of steps S505 to S508, assuming that the voltage waveform is being adjusted for nozzle A, one of the nozzles to be adjusted.

[0069] The process from steps S505 to S508 is based on a method called the nozzle displacement method. The nozzle displacement method is based on the assumption that "each nozzle of the liquid discharge head 23 always has a discharge characteristic that is deviated by approximately a constant amount relative to the reference nozzle." This deviation (difference) is called the displacement. This means that when the discharge volume prediction model for nozzle j (the nozzle with nozzle number j) is called Fj(w) and the discharge velocity prediction model is called Gj(w), it can be approximated by the following equation.

[0070] Fj(w) ≈ F(w) + Vd dj Gj(w) ≈ G(w) + V dj

[0071] Here, Vd dj V is the displacement of the discharge volume of nozzle j. dj is a scalar value representing the displacement of the nozzle j discharge velocity. Note that the following flowchart repeatedly estimates the nozzle displacement using past discharge results and estimates the optimal voltage waveform for the nozzle based on that displacement.

[0072] First, we will explain the case where the first voltage waveform adjustment is performed on nozzle A. Subscripts related to nozzle A will be omitted below if possible, as they are cumbersome.

[0073] In step S505 (first time), the determination unit 104 receives the nozzle number of nozzle A and the target discharge characteristics from the input unit 101 and determines the voltage waveform to be applied to nozzle A first (optimal voltage waveform). In the first voltage waveform adjustment, the displacement of nozzle A is unknown. Therefore, as the optimal voltage waveform, for example, a predetermined voltage waveform is always selected. Alternatively, using the reference models F(w) and G(w) learned in step S503, a voltage waveform w that is likely to make the discharge characteristics of the reference nozzle close to the target discharge characteristics may be searched for, and the obtained w may be selected as the optimal voltage waveform. By adopting this method, if the properties of nozzle A are sufficiently close to those of the reference nozzle, it can be expected that the discharge standard will be achieved immediately in the first voltage waveform adjustment. This method of determining the voltage waveform w can be performed in step S505 (second time), described later, by selecting the optimal voltage waveform when the displacement of nozzle A is set to zero.

[0074] The determination unit 104 sends the nozzle number of nozzle A and the voltage waveform to be applied to nozzle A to the discharge unit 105.

[0075] In step S506 (first time), the discharge unit 105 receives the nozzle number and voltage waveform of nozzle A from the determination unit 104, applies the above voltage waveform to the nozzle indicated by the above nozzle number, i.e., nozzle A, and discharges a droplet from nozzle A.

[0076] In step S507 (first time), the discharge measurement unit 106 observes the droplet discharged from nozzle A in step S506 and measures the discharge characteristics of the droplet (discharge volume and discharge speed). The measured discharge volume is denoted as Vd [pl] and the discharge speed as V [m / s].

[0077] In step S508 (first time), the determination unit 104 compares the measurement result from step S507 with the target discharge characteristics obtained in step S501 to determine whether the discharge standard has been met. This determination can be made by pre-determining the permissible errors of the discharge amount and discharge speed. For example, the absolute permissible error of the discharge amount can be set to Vd allow [pl], the absolute tolerance of the discharge speed is Vallow The discharge rate is predetermined to be [m / s]. In this case, the discharge standard is determined to have been met if the following conditions are met.

[0078] |Vd-Vd target | ≦ Vd allow and |VV target | ≦ V allow

[0079] This determination is not limited to this method and may be performed by other methods. For example, the relative tolerance of the discharge volume is Vd allow [Dimensionless], relative tolerance of discharge rate is V allow It is assumed that it is predetermined as [dimensionless]. In this case, it may be determined that the discharge criteria have been met if the following conditions are met.

[0080] |Vd-Vd target | / Vd target ≤ Vd allow and |VV target | / V target ≤ V allow

[0081] Naturally, if no discharge occurs at all, the discharge criteria will be deemed not met. Furthermore, even if discharge is performed, if it is accompanied by phenomena such as satellites or mist, the discharge criteria may also be deemed not met.

[0082] In step S508 (first time), the determination unit 104 stores the result of the first voltage waveform adjustment for nozzle A (a set of nozzle number, number of adjustments, voltage waveform, discharge result, and determination result of whether or not the discharge criterion was met) in the storage unit 103.

[0083] If it is determined that the discharge criteria have been met, the process proceeds to step S509, where the voltage waveform adjustment is performed on the next nozzle to be adjusted. If it is determined that the discharge criteria have not been met, the process returns to step S505, where a second voltage waveform adjustment is performed on nozzle A. The following section continues the explanation of the case where a second voltage waveform adjustment is performed on nozzle A.

[0084] In step S505 (second time), the determination unit 104 receives the nozzle number and target discharge characteristics of nozzle A from the input unit 101, and the first adjustment result of nozzle A from the storage unit 103. Based on this information, the determination unit 104 determines the voltage waveform to be applied to nozzle A next. This procedure will be explained.

[0085] Next, the determination unit 104 functions as an acquisition unit and calculates (acquires) the displacement of nozzle A. Various methods can be used to calculate the displacement.

[0086] For example, one method to calculate the displacement is to subtract the estimated discharge characteristics of a reference nozzle from the discharge result of the first discharge from nozzle A. Displacement amount Vd of discharge volume d [pl], discharge velocity displacement V d The values ​​in [m / s] are calculated using the following formulas:

[0087] Vd d = Vd-Vd e V d = VV e

[0088] Here, Vd e V is an estimated value of the discharge volume at the reference nozzle. e These are estimated values ​​of the discharge velocity at the reference nozzle. These values ​​are obtained by inputting the optimal voltage waveform selected in step S505 (first time) into the reference models F(w) and G(w) learned in step S503.

[0089] The above discharge volume Vd and discharge speed V are examples of measured values ​​of discharge characteristics obtained by applying the first voltage waveform to the nozzle A to be adjusted. The above estimated value of discharge volume Vd e and the estimated value V of the discharge speed e These are examples of estimated discharge characteristics obtained by applying the first voltage waveform to the reference models F(w) and G(w), respectively.

[0090] The displacement amount Vd of the above discharge volume d This refers to the above discharge rate Vd and the above estimated value Vd for discharge rate. e It is calculated based on the difference between the above. Note that the displacement amount Vd of the discharge volume is as described above. d This refers to the above discharge rate Vd and the above estimated value Vd for discharge rate. e The difference may be calculated by multiplying it by a predetermined value less than 1.

[0091] The displacement amount V of the discharge speed mentioned above. d This refers to the above-mentioned discharge rate V and the above-mentioned estimated value V of the discharge rate. e It is calculated based on the difference between the above. Note that the displacement amount V of the discharge speed is as described above. d This refers to the above-mentioned discharge rate V and the above-mentioned estimated value V of the discharge rate. e The difference may be calculated by multiplying it by a predetermined value less than 1.

[0092] Furthermore, if there are measured values ​​obtained by applying the optimal voltage waveform selected in step S505 (first time) to the reference nozzle, the displacement amount may be calculated using these values. Displacement amount Vd of discharge volume d [pl], discharge velocity displacement V d The values ​​in [m / s] are calculated using the following formulas:

[0093] Vd d = Vd-Vd r V d = VV r

[0094] Here, Vd r V is the measured value of the discharge volume at the standard nozzle. rThis is the measured value of the discharge velocity at the standard nozzle.

[0095] The measured value Vd of the above discharge volume r and measured value V of discharge speed r This is an example of measured values ​​of discharge characteristics obtained by applying the first voltage waveform to a reference nozzle.

[0096] The displacement amount Vd of the above discharge volume d This is the above discharge rate Vd and the measured value of the above discharge rate Vd r It is calculated based on the difference between the above. Note that the displacement amount Vd of the discharge volume is as described above. d This is the above discharge rate Vd and the measured value of the above discharge rate Vd r The difference may be calculated by multiplying it by a predetermined value less than 1.

[0097] The displacement amount V of the discharge speed mentioned above. d [m / s] represents the above-mentioned discharge speed V and the measured value of the above-mentioned discharge speed V. r It is calculated based on the difference between the above. Note that the displacement amount V of the discharge speed is as described above. d [m / s] represents the above-mentioned discharge speed V and the measured value of the above-mentioned discharge speed V. r The difference may be calculated by multiplying it by a predetermined value less than 1.

[0098] Next, the determination unit 104 determines the discharge volume prediction model F of nozzle A. A (w) Discharge velocity prediction model G for nozzle A A (w) is determined from the displacement. As mentioned above, these are defined by the following equations.

[0099] F A (w) = F(w) + Vd d G A (w) = G(w) + V d

[0100] The above discharge volume prediction model F A (w) and discharge rate prediction model G A(w) is an example of a nozzle model to be adjusted, which is a model that estimates the discharge characteristics of droplets discharged when a voltage waveform w is applied to the nozzle A to be adjusted.

[0101] The determination unit 104 uses the above-mentioned discharge volume prediction model F A (w) and discharge rate prediction model G A (w) is the displacement Vd of the reference models F(w) and G(w). d and V d It is defined by adding each of them together.

[0102] Next, the determination unit 104 is F A (w) is Vd target [pl] is close to G A (w) is V target We search for a voltage waveform w that is close to [m / s]. This search can be performed, for example, by searching for a voltage waveform w that minimizes the following objective function.

[0103]

number

[0104] Here, λ is a value that determines the weighting between discharge rate and discharge velocity. λ is a value that should be designed in advance, taking into account the difference in scale between discharge rate and discharge velocity, and the difference in importance between discharge rate and discharge velocity. Alternatively, λ = 1 may be used.

[0105] The displacement amount Vd of the above discharge volume d and the displacement amount V of the discharge speed d This is an example of a displacement amount that represents the amount of deviation in discharge characteristics between the reference nozzle and the nozzle A to be adjusted.

[0106] The above target discharge volume Vd target and target discharge rate V target This is an example of a target discharge characteristic, which is the target discharge characteristic of the droplet discharged from nozzle A to be adjusted. The discharge characteristic includes at least one of the discharge volume and discharge velocity of the droplet discharged from the nozzle.

[0107] The discharge amount prediction model F(w) and the discharge speed prediction model G(w) are an example of a reference nozzle model that estimates the discharge characteristics of droplets discharged when a voltage waveform is applied to the reference nozzle.

[0108] The determination unit 104 determines the displacement amount Vd of the discharge amount d and the displacement amount V of the discharge speed d and the target discharge amount Vd target and the target discharge speed V target and based on the discharge amount prediction model F(w) and the discharge speed prediction model G(w), determines the voltage waveform w to be applied to the adjustment target nozzle A.

[0109] Specifically, the determination unit 104 searches for a voltage waveform w such that the output values of the discharge amount prediction model F A (w) and the discharge speed prediction model G A (w) approach the target discharge amount Vd target and the target discharge speed V target respectively, and determines the voltage waveform w to be applied to the adjustment target nozzle A.

[0110] When searching for the optimal solution of the voltage waveform w, the voltage waveform that was selected in the past voltage waveform adjustment process but did not achieve the discharge standard is likely not to achieve the discharge standard even if it is selected again, so it may be excluded from the search target.

[0111] Alternatively, the determination unit 104 searches for a voltage waveform w such that the estimated discharge amount of the reference model is close to Vd target -Vd d [pl], and the estimated discharge speed of the reference model is close to V target -V d [m / s]. This search can be performed, for example, by searching for a voltage waveform w that minimizes the following objective function.

[0112]

Equation

[0113] The determination unit 104 determines the voltage waveform w to be applied to the adjustment target nozzle A by searching for a voltage waveform w in which the output values of the reference models F(w) and G(w) approach the values obtained by subtracting the displacement amounts Vd target and the target discharge speed V target from the target discharge amount Vd d and V d respectively.

[0114] Since the two methods described above are equivalent, either method can be used.

[0115] If the minimum value of the objective function can be obtained analytically, the optimal voltage waveform w can also be obtained analytically. Otherwise, the voltage waveform w is searched using an arbitrary method. An example is shown below.

[0116] If the range of voltage waveforms that can achieve normal discharge is known in advance as shown in FIG. 6 and the range is sufficiently small, the voltage waveform w can be searched exhaustively within that range, and the voltage waveform that minimizes the value of the objective function can be determined as the optimal voltage waveform. If the range of possible values of the voltage waveform w is too wide to be searched exhaustively, known methods such as the grid search method, random search method, Nelder-Mead method, and Bayesian optimization method can be used to efficiently search for the optimal voltage waveform w. In that case, the search may be terminated midway if a voltage waveform w is found such that the value of the objective function is smaller than a predetermined value. [[ID=二十一]] [[ID=二十二]]

[0117] [[ID=二十三]] [[ID=二十四]]The method for obtaining the optimal voltage waveform in the framework of single-objective optimization that optimizes a single objective function has been described. The method is not limited to this. For example, two objective functions, one related to the discharge amount and the other related to the discharge speed, may be defined, and the optimal voltage waveform may be obtained in the framework of multi-objective optimization that optimizes the two objective functions. Generally, in multi-objective optimization, a plurality of candidate optimal voltage waveforms are obtained, and one voltage waveform is selected according to some criteria. [[ID=二十五]] [[ID=二十六]]

[0118] [[ID=二十七]] The processes in steps S506 (second time), S507 (second time), and S508 (second time) are the same as those explained in steps S506 (first time), S507 (first time), and S508 (first time), respectively, so we will omit the explanation.

[0119] The following describes the case where the discharge standard is not met for nozzle A for N consecutive times from the 1st to the Nth time, and the (N+1)th voltage waveform adjustment is performed for nozzle A.

[0120] In step S505 (the N+1th time), the determination unit 104 receives the nozzle number and target discharge characteristics of nozzle A from the input unit 101, and the adjustment results for nozzle A from the 1st to the Nth time from the storage unit 103. Based on this information, the determination unit 104 determines the voltage waveform to be applied to nozzle A next. This procedure will be explained.

[0121] The determination unit 104 calculates the amount (displacement) of how much nozzle A is deviating from the reference nozzle. The displacement can be calculated by taking the average, median, trimmed average, weighted moving average, exponentially smoothed moving average, etc., of the displacement obtained from the 1st to N-1th discharge. For example, the case where the average value is used will be explained below. Displacement amount Vd of discharge volume d [pl] and the displacement amount V of the discharge speed d The values ​​in [m / s] can be calculated using the following formulas.

[0122] Vd d = Σ(Vd i -Vd ei ) / N V d = Σ(V i -V ei ) / N

[0123] Here, the subscript i represents the result of the i-th voltage waveform adjustment. That is, it means the following:

[0124] Vd i [pl]: Discharge volume measured in S507 (ith time) V i[m / s]: Discharge rate measured in S507 (ith time) Vd ei [pl]: Estimated discharge volume obtained by inputting the voltage waveform selected in S505 (ith time) into the reference model F(w) learned in S503. V ei [m / s]: Estimated discharge velocity obtained by inputting the voltage waveform selected in S505 (ith time) into the reference model G(w) learned in S503. The summation symbol Σ represents the sum as i ranges from 1 to N.

[0125] As described above, the determination unit 104 determines N displacement amounts Vd, which represent the amount of deviation in the discharge characteristics between the reference nozzle and the nozzle A to be adjusted, based on N different voltage waveforms (where N is an integer of 2 or more). i and V i When this is obtained, N displacement amounts Vd i and V i Based on at least one of the following: mean, median, trimmed mean, weighted moving mean, or exponential moving mean, the displacement Vd d and V d Calculate.

[0126] In this example, the displacement was calculated based on estimated values ​​of the discharge characteristics at the reference nozzle. However, as explained in step S505 (second time), the displacement may also be calculated based on measured values ​​of the discharge characteristics at the reference nozzle.

[0127] Since the displacement is calculated using all past voltage waveform adjustment results, it is expected that the accuracy of the displacement will gradually improve as the adjustment is repeated.

[0128] The processing after calculating the displacement is the same as in step S505 (second time), so the explanation is omitted.

[0129] The flowchart in Figure 5 shows that the voltage waveform adjustment process from step S505 to S508 is repeated until the actual discharge from nozzle A meets the discharge criteria. However, the maximum number of attempts for the voltage waveform adjustment process may be predetermined, and if a voltage waveform that meets the discharge criteria is not obtained even after reaching the maximum number of attempts, the process may be terminated midway. In this case, the determination unit 104 may store in the storage unit 103 one of the voltage waveforms that has been tried in the past, which has the smallest value of the objective function, as a representative.

[0130] Once voltage waveform adjustment is complete for all nozzles to be adjusted, proceed to step S510.

[0131] In step S510, the output unit 107 displays the voltage waveform adjustment results for each nozzle to be adjusted on a display device 17 such as a display. Figure 7 shows an example of the display. Figure 7(a) is a table that contains detailed information for each of the nozzles to be adjusted. Figure 7(a) shows that the nozzles to be adjusted are four nozzles represented by nozzle numbers 1 to 4, and that nozzle number 3 failed to adjust, while the other three nozzles were successfully adjusted. In the voltage waveform parameter column, the voltage waveform parameter at the time of successful voltage waveform adjustment is recorded, and in the case of failure to adjust the voltage waveform parameter, the voltage waveform parameter that was closest to the target discharge characteristics is recorded.

[0132] The output unit 107 is controlled to display, for each nozzle number, whether the voltage waveform adjustment was successful or unsuccessful, the voltage waveform parameters, the discharge volume, the discharge speed, the displacement of the discharge volume from the reference nozzle, and the displacement of the discharge speed from the reference nozzle. The output unit 107 functions as a control unit and is controlled to display information to identify nozzles that succeeded and failed in the voltage waveform adjustment determined by the determination unit 104.

[0133] Figure 7(b) is a table summarizing the adjustment results. The output unit 107 is controlled to display the success rate of voltage waveform adjustment for all nozzles.

[0134] By displaying the nozzle adjustment results, users can understand the success rate of voltage waveform adjustment and the nozzle numbers for which voltage waveform adjustment failed.

[0135] The display method is not limited to this. For example, the shape of the voltage waveform could be displayed as a graph.

[0136] The voltage waveform adjustment system 30 in Figure 1 comprises a voltage waveform adjustment device 10 and a liquid dispensing device 20. The liquid dispensing device 20 includes a liquid dispensing head 23 with a nozzle that dispenses droplets when a voltage waveform is applied. The voltage waveform adjustment device 10 adjusts the voltage waveform to be applied to the nozzle of the liquid dispensing head 23 of the liquid dispensing device 20 by transmitting a dispensing instruction to the liquid dispensing device 20 and receiving measurement results from the liquid dispensing device 20.

[0137] The above describes an example of the voltage waveform adjustment process flow by the voltage waveform adjustment device 10 according to this embodiment. As described above, the voltage waveform adjustment device 10 of the first embodiment makes it possible to perform voltage waveform adjustment for each nozzle at high speed, even when there are individual differences between nozzles that cannot be ignored.

[0138] However, the voltage waveform adjustment process is not limited to this, and various modifications are possible. Modifications are described below.

[0139] <Example 1> In the first embodiment, a method was used in which the nozzles to be adjusted were adjusted sequentially. The adjustment of the voltage waveform is not limited to this method, and other methods may be used. For example, in the first step, the initial voltage waveform is determined for each of the nozzles to be adjusted, and discharge and measurement are performed sequentially for each nozzle. Next, in the second step, the next voltage waveform is determined only for the nozzles to be adjusted that did not meet the discharge criteria in the first step, and discharge and measurement are performed sequentially. The process is repeated in the same manner thereafter.

[0140] <Modification 2> In the first embodiment, the displacement amount Vd of the discharge volume d [pl], discharge velocity displacement Vd The values ​​in [m / s] were calculated using the following formulas.

[0141] Vd d = Σ(Vd i -Vd ei ) / N V d = Σ(V i -V ei ) / N

[0142] The displacement is a value whose accuracy is expected to gradually improve with repeated adjustments. Conversely, a displacement determined from only a small number of voltage waveforms may have low reliability. Therefore, the displacement may be defined by multiplying it by a coefficient h(N), which is determined according to the number of trials N, as shown in the following equation.

[0143] Vd d = h(N)·Σ(Vd i -Vd ei ) / N V d = h(N)·Σ(V i -V ei ) / N

[0144] The coefficient h(N) is a function that increases monotonically with respect to the value of N and converges to 1 as N→∞. For example, the coefficient h(N) can be defined by the following equation.

[0145] h(N) = N / (N+1)

[0146] Introducing such coefficients has the effect of preventing the displacement amount determined from only a small number of voltage waveforms from becoming an extreme value.

[0147] The displacement amount Vd of the above discharge volume d The above discharge volume Vd i and the estimated discharge amount Vd ei It is calculated based on the difference between the two, the number of trials N, and a coefficient h(N) less than 1.

[0148] The displacement amount V of the discharge speed mentioned above. d The above discharge speed V iand the estimated discharge rate V ei It is calculated based on the difference between the two, the number of trials N, and a coefficient h(N) less than 1.

[0149] <Variation 3> In the first embodiment, the steps S502 for acquiring training data and S503 for learning the regression model were performed each time the voltage waveform was adjusted. However, steps S502 and S503 may not be performed each time the voltage waveform is adjusted. For example, steps S502 and S503 are applied to a reference nozzle of a certain liquid discharge head 23, and the parameters of the resulting regression model are stored in the storage unit 103. Then, when adjusting the voltage waveform of other liquid discharge heads 23, the parameters of the regression model are reused.

[0150] By adopting this configuration, the processing steps for adjusting the voltage waveform can be simplified.

[0151] <Modification 4> In the first embodiment, the nozzles of the liquid discharge head 23 were treated as targets for voltage waveform adjustment without distinction. However, the nozzles may be divided into predetermined groups, a reference nozzle may be determined for each group, and the voltage waveform may be adjusted by calculating the displacement amount relative to the reference nozzle.

[0152] For example, consider a case where the nozzles in the liquid discharge head 23 are arranged two-dimensionally (for example, in a grid or triangular grid). If it is known that each row of nozzles has different properties, the nozzles are divided into groups by row. Then, independently for each group, one nozzle is selected as the reference nozzle, and the rest are the nozzles to be adjusted. Then, the voltage waveform adjustment is performed on the nozzles to be adjusted in the same manner as in the first embodiment.

[0153] By adopting this configuration, the efficiency and accuracy of voltage waveform adjustment are increased.

[0154] <Modification 5> In this modified example, as in Modification 4 of the first embodiment, the nozzles are divided into predetermined groups. However, in Modification 4 of the first embodiment, there were individual differences between nozzles in each group that could not be ignored, but in this modified example, the individual differences between nozzles in each group are considered to be negligibly small. Therefore, by selecting one representative nozzle from each group and performing waveform adjustment on the representative nozzle group, it can be considered that waveform adjustment has been performed simultaneously on all nozzles belonging to all groups.

[0155] The voltage waveform adjustment device 10 selects one representative nozzle from each group. Then, it determines that one of the representative nozzles is the reference nozzle and the remaining nozzles are to be adjusted. Then, it performs voltage waveform adjustment on the nozzles to be adjusted in the same manner as in the first embodiment. The nozzles belonging to each group share the voltage waveform determined for the representative nozzle of that group.

[0156] By adopting this configuration, the efficiency of voltage waveform adjustment is increased.

[0157] <Variation 6> In the first embodiment, the results of voltage waveform adjustment were stored in the storage unit 103 of the voltage waveform adjustment device 10. However, the configuration of the voltage waveform adjustment device 10 is not limited to this.

[0158] For example, the liquid dispensing device 20 may be configured to include an additional memory unit, which stores the results of the voltage waveform adjustment. With this configuration, after the voltage waveform adjustment process by the voltage waveform adjustment device 10 is completed, the liquid dispensing device 20 can apply the adjusted voltage waveform to each nozzle without communicating with the voltage waveform adjustment device 10.

[0159] <Example 7> In the first embodiment, the voltage waveform adjustment device 10 and the liquid dispensing device 20 were configured as separate devices. However, the configuration of the devices is not limited to this.

[0160] For example, the measuring device included in the liquid dispensing device 20 may be made independent and operated as a separate device. Alternatively, for example, the voltage waveform adjustment device 10 and the liquid dispensing device 20 may be integrated into the same device.

[0161] <Second Embodiment> In the second embodiment, there are multiple liquid discharge heads, and a method for adjusting the voltage waveform for each liquid discharge head will be described. The same parts as in the first embodiment will be omitted from the explanation, and only the differences will be described.

[0162] Figure 8 shows a hardware configuration diagram according to the second embodiment. The voltage waveform adjustment system 30 includes a voltage waveform adjustment device 10 and a plurality of liquid dispensing devices 40, 50, and 60.

[0163] The voltage waveform adjustment device 10 is connected to a plurality of liquid dispensing devices 40, 50, and 60, and can adjust the voltage waveform for each liquid dispensing head provided by each of the liquid dispensing devices 40, 50, and 60. The liquid dispensing devices 40, 50, and 60 have the same configuration as the liquid dispensing device 20 of the first embodiment.

[0164] In the second embodiment, individual differences between nozzles in any liquid dispensing head are assumed to be negligibly small. However, non-negligible individual differences exist between liquid dispensing heads. Therefore, by selecting one representative nozzle from each liquid dispensing head and performing waveform adjustment on the representative nozzle group, it can be considered that waveform adjustment has been performed simultaneously on all nozzles belonging to all liquid dispensing heads.

[0165] The following assumes that there are three liquid dispensing heads.

[0166] The storage unit 103 of the voltage waveform adjustment device 10 can store the voltage waveform adjustment results for each nozzle to be adjusted (a set of nozzle number, number of adjustments, voltage waveform, discharge result, and determination result of whether or not the discharge criterion was met) for each of the connected liquid discharge devices 40, 50, and 60.

[0167] The voltage waveform adjustment device 10 selects one of the three liquid discharge heads as the reference liquid discharge head. Then, it selects a representative nozzle from the reference liquid discharge head as the reference nozzle. Using the reference nozzle, it performs learning data collection processing (same as step S502 in the first embodiment) and regression model learning processing (same as step S503 in the first embodiment).

[0168] Next, the voltage waveform adjustment device 10 selects one representative nozzle from the remaining two liquid discharge heads that were not selected as the reference liquid discharge head, and performs a voltage waveform adjustment process on that nozzle (same as steps S505 to S508 of the first embodiment).

[0169] The nozzles belonging to each liquid dispensing head share the voltage waveform determined for the representative nozzle of that liquid dispensing head.

[0170] The above describes an example of the voltage waveform adjustment process flow by the voltage waveform adjustment device 10 according to the second embodiment. As described above, the voltage waveform adjustment device 10 of the second embodiment makes it possible to perform voltage waveform adjustment for each liquid discharge head at high speed, even when there are individual differences between liquid discharge heads that cannot be ignored.

[0171] However, the voltage waveform adjustment process is not limited to this, and various modifications are possible. Modifications are described below.

[0172] <Example 1> In the second embodiment, individual differences between nozzles in any liquid dispensing head were considered to be negligibly small. However, in this modified example, individual differences between nozzles in any liquid dispensing head are considered to be non-negligible. That is, individual differences exist in the liquid dispensing heads, and individual differences also exist in the nozzles of each liquid dispensing head.

[0173] In this case, the voltage waveform adjustment device 10 selects one nozzle belonging to one of the three liquid discharge heads as the reference nozzle. Then, using the reference nozzle, it performs learning data collection processing (same as step S502 in the first embodiment) and regression model learning processing (same as step S503 in the first embodiment).

[0174] Next, the voltage waveform adjustment device 10 performs voltage waveform adjustment processing (same as steps S505 to S508 of the first embodiment) for all nozzles other than the reference nozzle.

[0175] In this modified version, even if there are significant individual differences between any nozzle in any of the liquid dispensing heads, it becomes possible to perform high-speed voltage waveform adjustment for each nozzle.

[0176] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention as described in the claims.

[0177] As described above, according to the first and second embodiments, it is possible to adjust the voltage waveform for each nozzle at high speed, even when there are individual differences between nozzles that cannot be ignored.

[0178] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by a process in which one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0179] The embodiments described above are merely examples of how the present invention can be implemented, and the technical scope of the invention should not be interpreted as being limited by them. In other words, the present invention can be implemented in various ways without departing from its technical concept or its main features.

[0180] This embodiment includes the following configuration. (Item 1) A voltage waveform adjusting device for adjusting the voltage waveform used to drive a first nozzle and a second nozzle that discharge liquid, An acquisition unit that acquires a displacement amount representing the amount of deviation in the discharge characteristics between the first nozzle and the second nozzle, A storage unit that stores a target discharge characteristic, which is the target discharge characteristic of the droplet discharged from the second nozzle, and a first nozzle model, which is a model for estimating the discharge characteristic of the droplet discharged when a voltage waveform is applied to the first nozzle, A determination unit that determines the voltage waveform to be applied to the second nozzle based on the acquired displacement and the stored target discharge characteristics, using the stored first nozzle model, A voltage waveform adjustment device characterized by comprising the following features. (Item 2) The voltage waveform adjustment device according to item 1, characterized in that the amount of displacement is calculated based on the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the estimated value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle model. (Item 3) The voltage waveform adjustment device according to item 1, characterized in that the amount of displacement is calculated based on the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the measured value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle. (Item 4) The voltage waveform adjusting device according to any one of items 1 to 3, characterized in that the discharge characteristics include at least one of the discharge volume and discharge speed of the droplets discharged from the nozzle. (Item 5) The aforementioned determination unit, A second nozzle model, which is a model for estimating the discharge characteristics of droplets discharged when a voltage waveform is applied to the second nozzle, is defined by adding the displacement amount to the first nozzle model. A voltage waveform adjustment device according to any one of items 1 to 4, characterized in that it determines the voltage waveform to be applied to the second nozzle by searching for a voltage waveform in which the output value of the second nozzle model approaches the target discharge characteristics. (Item 6) The voltage waveform adjustment device according to any one of items 1 to 4, characterized in that the determination unit determines the voltage waveform to be applied to the second nozzle by searching for a voltage waveform in which the output value of the first nozzle model approaches a value obtained by subtracting the displacement amount from the target discharge characteristics. (Item 7) The voltage waveform adjustment device according to any one of items 1 to 6, characterized in that when N displacement amounts representing the amount of deviation in discharge characteristics between the first nozzle and the second nozzle are obtained based on N different voltage waveforms (where N is an integer of 2 or more), the determination unit calculates the displacement amount based on at least one of the average value, median value, trimmed average value, weighted moving average value, and exponentially smoothed moving average value of the N displacement amounts. (Item 8) The voltage waveform adjustment device according to item 2, characterized in that the amount of displacement is calculated by multiplying the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the estimated value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle model by a predetermined value of less than 1. (Item 9) The voltage waveform adjustment device according to item 3, characterized in that the amount of displacement is calculated by multiplying the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the measured value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle by a predetermined value of less than 1. (Item 10) The voltage waveform adjustment device according to any one of items 1 to 9, further comprising a control unit that controls the display of information for identifying nozzles that have succeeded and failed in voltage waveform adjustment based on the determination of the determination unit. (Item 11) A voltage waveform adjustment device described in any one of items 1 to 10, The system includes a liquid dispensing device equipped with a liquid dispensing head having a nozzle that dispenses droplets by applying a voltage waveform, The voltage waveform adjustment system is characterized in that the voltage waveform adjustment device adjusts the voltage waveform to be applied to the nozzle of the liquid discharge head of the liquid discharge device by transmitting a discharge instruction to the liquid discharge device and receiving a measurement result from the liquid discharge device. (Item 12) A method for adjusting the voltage waveform of a voltage waveform adjustment device used to drive a first nozzle and a second nozzle that discharge liquid, An acquisition step to acquire a displacement amount representing the amount of deviation in the discharge characteristics between the first nozzle and the second nozzle, A storage step that stores a target discharge characteristic, which is the target discharge characteristic of the droplet discharged from the second nozzle, and a first nozzle model, which is a model for estimating the discharge characteristic of the droplet discharged when a voltage waveform is applied to the first nozzle. A determination step in which the voltage waveform to be applied to the second nozzle is determined based on the acquired displacement and the stored target discharge characteristics, using the stored first nozzle model; A method for processing voltage waveforms, characterized by comprising a voltage waveform adjustment device. (Item 13) A program to cause a computer to function as a voltage waveform adjuster as described in any one of items 1 through 10. [Explanation of Symbols]

[0181] 101 Input Section 102 Learning Department 103 Storage section 104 Decision Section 105 Discharge part 106 Discharge Measurement Unit 107 Output section

Claims

1. A voltage waveform adjusting device for adjusting the voltage waveform used to drive a first nozzle and a second nozzle that discharge liquid, An acquisition unit that acquires a displacement amount representing the amount of deviation in the discharge characteristics between the first nozzle and the second nozzle, A storage unit that stores a target discharge characteristic, which is the target discharge characteristic of the droplet discharged from the second nozzle, and a first nozzle model, which is a model for estimating the discharge characteristic of the droplet discharged when a voltage waveform is applied to the first nozzle, A determination unit that determines the voltage waveform to be applied to the second nozzle based on the acquired displacement and the stored target discharge characteristics, using the stored first nozzle model, A voltage waveform adjustment device characterized by comprising the following features.

2. The voltage waveform adjustment device according to claim 1, characterized in that the amount of displacement is calculated based on the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the estimated value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle model.

3. The voltage waveform adjustment device according to claim 1, characterized in that the amount of displacement is calculated based on the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the measured value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle.

4. The voltage waveform adjusting device according to claim 1, characterized in that the discharge characteristics include at least one of the discharge amount and discharge speed of the droplets discharged from the nozzle.

5. The aforementioned determination unit, A second nozzle model, which is a model for estimating the discharge characteristics of droplets discharged when a voltage waveform is applied to the second nozzle, is defined by adding the displacement amount to the first nozzle model. The voltage waveform adjustment device according to claim 1, characterized in that it determines the voltage waveform to be applied to the second nozzle by searching for a voltage waveform in which the output value of the second nozzle model approaches the target discharge characteristics.

6. The voltage waveform adjustment device according to claim 1, characterized in that the determination unit determines the voltage waveform to be applied to the second nozzle by searching for a voltage waveform in which the output value of the first nozzle model approaches a value obtained by subtracting the displacement amount from the target discharge characteristics.

7. The voltage waveform adjustment device according to claim 1, characterized in that when the determination unit obtains N displacement amounts representing the amount of deviation in the discharge characteristics between the first nozzle and the second nozzle based on N different voltage waveforms (where N is an integer of 2 or more), it calculates the displacement amount based on at least one of the average value, median value, trimmed average value, weighted moving average value, and exponentially smoothed moving average value of the N displacement amounts.

8. The voltage waveform adjustment device according to claim 2, characterized in that the amount of displacement is calculated by multiplying the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the estimated value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle model by a predetermined value of less than 1.

9. The voltage waveform adjustment device according to claim 3, characterized in that the amount of displacement is calculated by multiplying the difference between the measured value of the discharge characteristics obtained by applying the first voltage waveform to the second nozzle and the measured value of the discharge characteristics obtained by applying the first voltage waveform to the first nozzle by a predetermined value of less than 1.

10. The voltage waveform adjustment device according to claim 1, further comprising a control unit that controls the display of information for identifying nozzles that have succeeded and unsuccessfully adjusted the voltage waveform as determined by the determination unit.

11. A voltage waveform adjustment device according to any one of claims 1 to 10, The system includes a liquid dispensing device equipped with a liquid dispensing head having a nozzle that dispenses droplets by applying a voltage waveform, The voltage waveform adjustment system is characterized in that the voltage waveform adjustment device adjusts the voltage waveform to be applied to the nozzle of the liquid discharge head of the liquid discharge device by transmitting a discharge instruction to the liquid discharge device and receiving a measurement result from the liquid discharge device.

12. A method for adjusting the voltage waveform of a voltage waveform adjustment device used to drive a first nozzle and a second nozzle that discharge liquid, An acquisition step to acquire a displacement amount representing the amount of deviation in the discharge characteristics between the first nozzle and the second nozzle, A storage step that stores a target discharge characteristic, which is the target discharge characteristic of the droplet discharged from the second nozzle, and a first nozzle model, which is a model for estimating the discharge characteristic of the droplet discharged when a voltage waveform is applied to the first nozzle. A determination step in which the voltage waveform to be applied to the second nozzle is determined based on the acquired displacement and the stored target discharge characteristics, using the stored first nozzle model; A method for processing voltage waveforms, characterized by comprising a voltage waveform adjustment device.

13. A program for causing a computer to function as a voltage waveform adjustment device according to any one of claims 1 to 10.

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