Inkjet recording device and program

Abstract

Provided are an inkjet recording device and program with which it is possible to obtain a more stable image quality in a formed image.　This inkjet recording device 100 comprises: an inkjet head 20; a carriage 111 on which the inkjet head 20 is mounted; a setting unit (control unit 40) that sets at least one among the speed and acceleration of the carriage 111 for each position of the carriage 111; an acquisition unit (control unit 40) that acquires drive cycle dependency information about the droplet speed of ink discharged from the inkjet head 20; and a correction unit (control unit 40) that corrects a control parameter during discharge of ink from the inkjet head 20 on the basis of the at least one among the speed and the acceleration of the carriage, and the drive cycle dependency information about the droplet speed.

Description

[Technical Field]

[0001] This invention relates to an inkjet recording device and a program. [Background technology]

[0002] There are inkjet recording devices that record images, thin films, wiring, and three-dimensional structures by applying pressure fluctuations to ink supplied through an ink channel in a pressure chamber located along the ink channel, and then ejecting the ink from numerous nozzles, each communicating with a number of pressure chambers. This inkjet recording device forms an image on a recording medium by ejecting ink droplets through the driving of an inkjet head by a carriage equipped with an inkjet head, which scans along a transport axis. The driving cycle of the inkjet head is generated based on an output signal obtained from a linear encoder, synchronized with the carriage's scanning.

[0003] In this regard, Patent Document 1 describes an invention for dynamically changing the timing of pulses that drive a print head based on the carriage speed and acceleration. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2002-002046 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As described above, since the drive cycle of the inkjet is determined based on the position information of the carriage, when the conveyance speed of the inkjet head is not constant, the drive cycle and drive frequency of the inkjet head change. Further, after droplets are ejected in the pressure chamber of the inkjet head, a reverberation wave is generated and affects the droplets ejected thereafter. Therefore, when the drive frequency of the inkjet head changes, the degree of influence by this reverberation wave also changes, and thus the droplet speed of the ink also changes. And when the droplet speed of the ink changes, there is a problem that the landing positions of the droplets vary and density unevenness occurs in the formed image. FIG. 13 shows an example of the drive cycle of the inkjet head and the droplet speed of the ink when the conveyance speed of the inkjet head is not constant. In the example shown in FIG. 13, the horizontal axis represents the time (s) after the start of driving the inkjet head, and the vertical axis represents the conveyance speed of the inkjet head (m / s: solid line), the drive cycle of the inkjet head (μs: broken line), and the droplet speed of the ink (m / s: dashed-dotted line). During the period in which the conveyance speed of the inkjet head is accelerating after the start of driving the inkjet head, the drive cycle of the inkjet head gradually becomes smaller. Also, the droplet speed of the ink does not stabilize and fluctuates periodically, and the amplitude gradually becomes larger. In the invention described in Patent Document 1, the variation in the landing positions of the droplets due to the change in the drive frequency (cycle) of the inkjet head is not compensated, and the above problem is not solved.

[0006] An object of this invention is to provide an inkjet recording apparatus and a program that can obtain a more stable image quality in the formed image.

Means for Solving the Problems

[0007] In order to achieve the above object, the inkjet recording apparatus of the invention described in claim 1 is Inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. Equipped with, The correction unit calculates a grayscale profile showing the correspondence between the position of the carriage and the density of the formed image, based on at least one of the carriage's speed and acceleration, and information on the drive cycle dependence of the droplet speed, and corrects the control parameters of the ink ejection of the inkjet head to cancel out density unevenness in the grayscale profile. Furthermore, the inkjet recording apparatus of the invention described in claim 2 is Inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. Equipped with 、 The correction unit corrects the control parameters when the carriage speed is not constant. ru.

[0008] Furthermore, claims 3 The inkjet recording apparatus of the invention described above is Inkjet head and A carriage equipped with the aforementioned inkjet head, A detection unit that detects at least one of the carriage's velocity and acceleration for each pixel of the image to be formed, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. It is equipped with.

[0009] Furthermore, claims 4 The inkjet recording apparatus of the invention described above is Inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, A detection unit that detects at least one of the carriage's velocity and acceleration for each pixel of the image to be formed, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. It is equipped with.

[0010] Furthermore, claims 5 The invention described in the claim 3 or 4 In the inkjet recording apparatus described above, The detection unit is provided in the inkjet head or the carriage.

[0011] Furthermore, claims 6 The invention described in the claim 3 or 4 In the inkjet recording apparatus described above, The correction unit corrects the control parameters when the carriage speed is not constant.

[0012] Furthermore, claims 7 The invention described in the claim 2 from 4 In an inkjet recording device described in any one of the following paragraphs, Three-dimensional objects are used as the target for image formation.

[0013] Furthermore, claims 8 The invention described in the claim 2 from 4 In an inkjet recording device described in any one of the following paragraphs, The correction unit corrects the image data as a control parameter.

[0014] Furthermore, claims 9 The invention described in the claim2 from 4 In an inkjet recording device described in any one of the following paragraphs, The correction unit corrects the discharge signal as a control parameter.

[0015] Furthermore, claims 10 The invention described in the claim 2 from 4 In an inkjet recording device described in any one of the following paragraphs, The correction unit performs the correction by selecting the drive waveform as a control parameter.

[0016] Furthermore, claims 11 The invention described in the claim 3 or 4 In the inkjet recording apparatus described above, The correction unit corrects the distance between the inkjet head and the recording medium and the angle of the inkjet head relative to the recording medium as control parameters. Furthermore, the inkjet recording apparatus of the invention described in claim 12 is Inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. Equipped with, The correction unit corrects the distance between the inkjet head and the recording medium and the angle of the inkjet head relative to the recording medium as control parameters.

[0017] Furthermore, claims 13 The invention described in the claim 11 In the inkjet recording apparatus described above, The correction unit corrects the distance between the inkjet head and the recording medium in a direction that widens the distance when the droplet velocity is faster than a predetermined reference value, and in a direction that narrows the distance when the droplet velocity is slower than a predetermined reference value.

[0018] Furthermore, claims 14 The invention described in the claim 11 In the inkjet recording apparatus described above, The correction unit corrects the angle of the inkjet head with respect to the recording medium so that when the droplet velocity is faster than a predetermined reference value, the landing positions of the droplets ejected from the inkjet head are sparse, and when the droplet velocity is slower than a predetermined reference value, the landing positions of the droplets ejected from the inkjet head are dense.

[0019] Furthermore, claims 15 The invention described in the claim 2 from 4 In an inkjet recording device described in any one of the following paragraphs, Equipped with a robotic arm, The robot arm includes the carriage.

[0020] Furthermore, claims 16 The program of the invention described is Inkjet head and A carriage equipped with the aforementioned inkjet head, A computer for an inkjet recording device equipped with, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage. An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head. A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. To function as 、 The correction unit corrects the control parameters when the carriage speed is not constant. ru. Furthermore, the program of the invention described in claim 17 is Inkjet head and A carriage equipped with the aforementioned inkjet head, A computer for an inkjet recording device equipped with, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage. An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head. A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. To make it function as, The correction unit corrects the distance between the inkjet head and the recording medium and the angle of the inkjet head relative to the recording medium as control parameters. [Effects of the Invention]

[0021] According to the present invention, more stable image quality can be obtained in the formed image. [Brief explanation of the drawing]

[0022] [Figure 1] This figure shows an example of a robotic arm equipped with a carriage that has an inkjet head according to this embodiment. [Figure 2] This is a block diagram showing the functional configuration of the inkjet recording device of this embodiment. [Figure 3] This figure shows an example of the dependence of droplet velocity on the driving period. [Figure 4] This is a flowchart of the control parameter correction process according to the first embodiment. [Figure 5A] This figure shows an example of a grayscale profile. [Figure 5B] This figure shows an example of a concentration correction profile. [Figure 6] This is a flowchart of the control parameter correction process according to the second embodiment. [Figure 7] This figure shows an example of the change in the distance between adjacent dots. [Figure 8] This is a flowchart of the control parameter correction process according to Modification 1 of the second embodiment. [Figure 9] This figure shows an example of the correction time for the discharge signal. [Figure 10] This is a flowchart of the control parameter correction process according to Modification 2 of the second embodiment. [Figure 11] This figure shows an example of a waveform pattern for a drive waveform. [Figure 12] This is a flowchart of the control parameter correction process according to Modification 3 of the second embodiment. [Figure 13] This figure shows examples of inkjet head transport speed, drive cycle, and ink droplet velocity. [Modes for carrying out the invention]

[0023] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0024] <First Embodiment> (1. Configuration of an inkjet recording device) The inkjet recording apparatus 100 of this embodiment is, for example, an inkjet recording apparatus that forms an image on a three-dimensional object (recording medium), and includes a robot arm body 11 equipped with a carriage 111 on which an inkjet head 20 is mounted, as shown in Figure 1.

[0025] Figure 2 is a block diagram showing the functional configuration of the inkjet recording device 100 according to this embodiment. The inkjet recording device 100 includes a robot arm unit 10, an inkjet head 20, a drive waveform signal generation unit 30, a control unit 40, a storage unit 50, a communication unit 60, an operation reception unit 71, a display unit 72, a power supply unit 80, and the like.

[0026] The robot arm unit 10 comprises a robot arm body 11 equipped with a carriage 111 and a robot arm drive control unit 12. The robot arm body 11 is a 6-axis articulated robot, and for example, even if the recording medium is a three-dimensional object and the image forming surface of the recording medium is curved, the inkjet head 20 can be positioned at a predetermined distance from the image forming surface. Furthermore, the robot arm body 11 is not limited to 6 axes; an articulated robot with an appropriate number of axes, such as 5 axes or 7 axes, can be used. Note that since articulated robots themselves are well known, a detailed explanation will be omitted. The robot arm drive control unit 12 drives the robot arm body 11 under the control of the control unit 40. Furthermore, the robot arm drive control unit 12 is equipped with an encoder 121. The encoder 121 detects the rotation of the drive motor of the robot arm drive control unit 12 and detects the position of the carriage 111 by outputting a signal corresponding to the direction of rotation for each rotation of a predetermined angle.

[0027] The inkjet head 20 ejects ink onto a recording medium to record images and other data. The inkjet head 20 includes a plurality of recording elements 20a and a head drive unit 24, among other components. Each recording element 20a includes a nozzle 21, an ink channel 22, a piezoelectric element 23, and the like. The head drive unit 24 applies a drive signal (drive waveform) to the selected piezoelectric element 23 to deform the piezoelectric element 23. Ink is supplied to each of the multiple nozzles 21 from a common supply path via an ink channel 22 that communicates with each nozzle 21. Each ink channel 22 includes a pressure chamber, and pressure fluctuations are applied to the ink in the pressure chamber by deformation in response to the application of a driving voltage to a piezoelectric element 23 located along (or forming part of) the wall of the pressure chamber. The piezoelectric element 23 applies pressure fluctuations corresponding to the driving waveform to the ink supplied to the nozzle 21, causing ink droplets to be ejected from the nozzle 21 and an image to be recorded. The inkjet recording device 100 is equipped with a number of inkjet heads 20 corresponding to the number of colors and types of ink ejected in a single image recording operation in the inkjet recording device 100. These inkjet heads 20 are capable of multi-drop ink ejection, which continuously ejects multiple ink droplets, merges them midway, and lands them as a single droplet in the corresponding pixel range (same pixel range), and the density gradation of each pixel range can be determined according to the number of ink droplets.

[0028] The drive waveform signal generation unit 30 generates the drive waveform that the head drive unit 24 outputs to the recording element 20a. The drive waveform signal generation unit 30 converts digital data representing a predetermined drive waveform into analog, and outputs a signal with amplified voltage and current as the drive waveform to the head drive unit 24, although this is not particularly limited. The generated drive waveform may include not only trapezoidal or rectangular wave shapes that eject ink, but also drive waveforms that cause a more gradual pressure change in the ink (such as a triangular wave; the pulse width is, for example, the half-width (width of the part of the amplitude that is 50% or more). It may also be a value other than 50%).

[0029] The control unit 40 is a processor that comprises a CPU 41 (Central Processing Unit) and RAM 42 (Random Access Memory) and comprehensively controls various operations of the inkjet recording device 100. The CPU 41 performs various calculations and executes control operations. The RAM 42 provides the CPU 41 with working memory space and stores temporary data. Based on the image data to be recorded and setting data related to image recording, the control unit 40 controls the output of the drive waveform related to the ink ejection operation of the inkjet head 20 to the recording element 20a.

[0030] Furthermore, the control unit 40 sets at least one of the velocity and acceleration of the carriage 111 for each position of the carriage 111 by storing a carriage coordinate-carriage velocity table or a carriage coordinate-carriage acceleration table, which will be described later, in the storage unit 50. At this time, the control unit 40 functions as a setting unit. Furthermore, the control unit 40 acquires a droplet velocity-drive cycle characteristic table from the storage unit 50 as information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head 20. At this time, the control unit 40 functions as an acquisition unit. Furthermore, the control unit 40 corrects the control parameters for ink ejection of the inkjet head 20 based on at least one of the carriage 111's speed and acceleration, and information on the drive cycle dependence of the droplet velocity. In this case, the control unit 40 functions as a correction unit. Here, the control parameters are image data, output signal, and drive waveform.

[0031] The storage unit 50 stores image data to be recorded, as well as various programs and setting data. The storage unit 50 has at least non-volatile memory, and may also have volatile memory (RAM). Image data may be stored in RAM. Non-volatile memory is, for example, flash memory, and may also have an HDD (Hard Disk Drive) in addition to or instead of this. Note that a part of the storage unit 50 may be held by the inkjet head 20, etc. Parameter information specific to the inkjet head 20 and information on initial abnormal nozzles may be stored in the non-volatile memory of the inkjet head 20. This information may be read by the control unit 40 during initial setup after the inkjet head 20 is mounted on the inkjet recording device 100, and may be integrally stored and managed in the storage unit 50 of the inkjet recording device 100.

[0032] The memory unit 50 also stores waveform setting data 51. The waveform setting data 51 stores waveform pattern data of the drive waveform to be output to each recording element 20a. The waveform pattern data stored here includes information on the start timing, pulse width, and voltage amplitude of the drive waveform corresponding to each ink ejection when multiple ink ejections are performed continuously. The pulse width information may be a parameter obtained from the non-volatile memory of the inkjet head 20. These may be the digital data that forms the basis of the drive waveform generated by the drive waveform signal generation unit 30.

[0033] Furthermore, the storage unit 50 stores a carriage coordinate-carriage velocity table that shows a pre-set correspondence between the carriage coordinates indicating a predetermined position of the carriage 111 and the velocity of the carriage 111. Alternatively, instead of the carriage coordinate-carriage velocity table, a carriage coordinate-carriage acceleration table that shows a pre-set correspondence between the carriage coordinates and the acceleration of the carriage 111 may be stored. Furthermore, the memory unit 50 stores a droplet velocity-drive cycle characteristic table calculated by simulation, which shows the correspondence between the droplet velocity of the ink ejected by the inkjet head 20 and the drive cycle of the inkjet head 20. Here, Figure 3 is a diagram showing an example of the dependence of the ink droplet velocity on the drive cycle of the inkjet head 20. As shown in Figure 3, it can be seen that when the drive cycle of the inkjet head 20 is relatively short (for example, 40 to 80 us), the ink droplet velocity is unstable.

[0034] The communication unit 60 executes and controls communication with external devices. The communication unit 60 can connect to an external computer based on a communication standard such as TCP / IP, acquire job data including image data to be recorded, and output the status of the image recording operation based on the job data. Alternatively, the communication unit 60 may be directly connected to peripheral devices via USB (Universal Serial Bus) or the like to send and receive data.

[0035] The operation reception unit 71 receives input operations from a user or the like and outputs the received content as an input signal to the control unit 40. The operation reception unit 71 may include, for example, a touch panel or a push-button switch. The touch panel may be positioned overlapping with the display screen of the display unit 72, and the operation content may be identified in synchronization with the content displayed on the display screen.

[0036] The display unit 72 displays information to the user, such as status and selection menus. The display unit 72 includes, for example, a display screen and indicators (lamps). The display unit 72 may have, for example, a liquid crystal display, and can display various characters and shapes on the display screen using a dot matrix. The indicators may be used, for example, LED lamps to indicate whether power is supplied or not, or whether there is an operational abnormality.

[0037] The power supply unit 80 supplies power at voltages corresponding to each part of the inkjet recording device 100. The drive board of the inkjet head 20 outputs a voltage corresponding to the peak voltage of each drive waveform.

[0038] (2. Operation of the inkjet recording device) Next, the control parameter correction process for the inkjet head 20 in the inkjet recording device 100 of this embodiment will be described. The control unit 40 performs the control parameter correction process of this embodiment before image formation by the inkjet head 20. Figure 4 is a flowchart showing the flow of the control parameter correction process.

[0039] First, the control unit 40 obtains the carriage coordinate-carriage velocity table from the storage unit 50 (step S1). Next, the control unit 40 obtains the droplet velocity-driving period characteristic table from the storage unit 50 (step S2). Next, the control unit 40 calculates a carriage coordinate-droplet velocity table showing the correspondence between carriage coordinates and ink droplet velocities from the carriage coordinate-carriage velocity table acquired in step S1 and the droplet velocity-drive period characteristic table acquired in step S2 (step S3). Next, the control unit 40 calculates a grayscale profile, as shown in Figure 5A, which shows the correspondence between carriage coordinates and the density of the resulting image, based on the carriage coordinate-droplet velocity table calculated in step S3 (step S4). Next, the control unit 40 calculates a density correction profile shown in Figure 5B that cancels out the density unevenness in the density profile calculated in step S4 (step S5). Here, the examples shown in Figures 5A and 5B are for so-called solid printing where all pixels are ejected. Next, the control unit 40 corrects the density of the image data to be recorded (control parameters) based on the density correction profile calculated in step S5 (step S6), and then terminates the process. Here, the control unit 40 may perform the control parameter correction process using a carriage coordinate-carriage acceleration table instead of a carriage coordinate-carriage velocity table.

[0040] <Second Embodiment> In the inkjet recording device 100 of this embodiment, the carriage 111 is equipped with a detection unit 111a. The detection unit 111a is a sensor that detects at least one of the speed and acceleration of the carriage 111 and outputs a detection signal to the control unit 40. The detection unit 111a may also be equipped on the inkjet head 20. By equipping the detection unit 111a on the carriage 111 or the inkjet head 20 in this way, the speed and acceleration of the inkjet head 20 can be detected more accurately than when the detection unit 111a is equipped on a part of the robot arm body 11 other than the carriage 111. The other components are the same as those of the first embodiment described above.

[0041] Next, the control parameter correction process for the inkjet head 20 in the inkjet recording apparatus 100 of this embodiment will be described. The control unit 40 performs the control parameter correction process of this embodiment while the inkjet head 20 is forming an image. Figure 6 is a flowchart showing the flow of the control parameter correction process in this embodiment.

[0042] First, the control unit 40 obtains the current position information of the carriage 111 from the encoder 121 (step S11). Next, the control unit 40 obtains the average value VH of the speed of the carriage 111 at the pixel corresponding to the current position of the carriage 111 from the detection unit 111a in step S11. N , , Here, the average value of the speed of the carriage 111 at the pixel corresponding to the current position is, for example, the average value of the speed when the inkjet head 20 passes from the (N - 1)-th pixel where ejection is performed to the N-th pixel where ejection is to be performed next. Next, the control unit 40 uses the average value VH of the speed of the carriage 111 at the pixel corresponding to the current position obtained in step S_{12} N to calculate the drive period T at the pixel corresponding to the current position (for example, the (N - 1)-th pixel to the N-th pixel) based on the following formula (1) (step S13). N T N = d N / VH N …Formula (1) Here, d N is the distance from the (N - 1)-th pixel to the N-th pixel on the input image data. Next, the control unit 40 obtains the droplet speed - drive period characteristic table from the storage unit 50 (step S14). Next, the control unit 40 obtains the droplet speed DV at the pixel corresponding to the current position from the drive period T at the pixel corresponding to the current position calculated in step S13 N and the droplet speed - drive period characteristic table obtained in step S14 (step S15). N Next, the control unit 40 calculates the droplet flight time t at the pixel corresponding to the current position from the droplet speed DV obtained in step S15 N and the distance Gap from the nozzle surface of the inkjet head 20 to the image formation surface of the recording medium based on the following formula (2) (step S16). N t N = Gap / DV N …Formula (2) Here, when calculating the droplet flight time t N the influence of air resistance on the ink droplets may be considered. ​​​

[0043] Next, the control unit 40 calculates the droplet flight time t in step S16. N and the average value VH of the carriage 111 velocity at the pixel corresponding to the current position N By calculating the position where the ink droplet lands on the image-forming surface, the distance D between adjacent dots in the pixel corresponding to the current position can be calculated using the following equation (3). N Calculate (Step S17). D N = VH N ·t N - VH N-1 ·t N-1 + d N ...Formula (3) Here, Figure 7 shows the distance D between adjacent dots. N An example of the change in [value] is shown. In the example shown in Figure 7, the horizontal axis represents the position (mm) of carriage 111, and the vertical axis represents the distance D between adjacent dots. N This is the change in (um).

[0044] Next, the control unit 40 calculates the distance between adjacent dots D in step S17. N The distance d from the (N-1)th pixel to the (N)th pixel on the input image data. N A density correction value is calculated that is equal to the target value (where there is no density unevenness) (Step S18). Specifically, distance d N For the distance between adjacent dots, D N If the value is small, the concentration is corrected to be lower; if it is large, the concentration is corrected to be higher. Next, the control unit 40 corrects the density of the image data to be recorded (control parameters) based on the density correction value calculated in step S18 (step S19), and then terminates the process.

[0045] (Variation 1) Next, a modified example 1 of the second embodiment described above will be explained. Figure 8 is a flowchart showing the control parameter correction process for this modified example. The control unit 40 performs the control parameter correction process for this modified example while the inkjet head 20 is forming an image. The following will focus on explaining the differences from the second embodiment described above. The configuration of the inkjet recording device 100 in this modified example is the same as that of the inkjet recording device 100 in the second embodiment described above.

[0046] In the control parameter correction process of this modified example shown in Figure 8, first, the control unit 40 performs steps S21 to S27, which are the same as steps S11 to S17 of the control parameter correction process of the second embodiment described above.

[0047] Next, the control unit 40 calculates the distance between adjacent dots D in step S27. N The distance d from the (N-1)th pixel to the (N)th pixel on the input image data. N The ink ejection signal is corrected to be equal to the target value (where there is no density unevenness). Specifically, the control unit 40 corrects the ejection signal time Δta using the following equation (5) so that the following equation (4) is satisfied. N Calculate (Step S28). VH N ·t N - VH N ·Δta N - VH N-1 ·t N-1 = 0...Equation (4) Δta N = t N - t N-1 ·VH N-1 / VH N …Equation (5) Here, VH N ·Δta N VH is the average speed at which the inkjet head 20 passes the Nth pixel that will be ejected next. N This is the amount of shift in the droplet landing position due to signal correction, assuming that the inkjet head 20 is moving. Next, the control unit 40 calculates the correction time Δta of the discharge signal calculated in step S28. N Based on this, the discharge signal (control parameter) is corrected (step S29), and the process is terminated.

[0048] Here, Figure 9 shows the correction time Δta of the discharge signal. NAn example is shown below. In the example shown in Figure 9, the horizontal axis represents the position (mm) of the carriage 111, and the vertical axis represents the correction time Δta of the discharge signal. N (us) In the examples shown in Figures 7 and 9, the distance between adjacent dots D N If the amount of change becomes larger than the target value where there is no density unevenness, the time for applying the discharge signal is corrected to a negative value (in the direction of increasing the drive frequency). Also, the distance between adjacent dots D N If the amount of change becomes small, the time for applying the discharge signal is corrected to a positive value (in the direction of slowing down the drive frequency). Furthermore, the examples shown in Figures 7 and 9 represent so-called solid printing, where ejection occurs at all pixels. When ejection is performed intermittently, the print becomes discontinuous rather than continuous, as shown in Figures 7 and 9.

[0049] In the above modified example, the control unit 40 performs the control parameter correction process during image formation by the inkjet head 20, but is not limited to this. Correction may be performed for all pixels before image formation. When correction is performed during image formation, the correction is based on the amount of deviation in the droplet landing position from the N-1 pixel to the N pixel, with the N-1 pixel as the reference. However, when correction is performed for all pixels before image formation, for example, the correction may be based on the amount of deviation in the droplet landing position from the 0th pixel as the reference.

[0050] (Modification 2) Next, a modified example 2 of the second embodiment described above will be explained. Figure 10 is a flowchart showing the control parameter correction process for this modified example. The control unit 40 performs the control parameter correction process for this modified example while the inkjet head 20 is forming an image. The following will focus on explaining the differences from the second embodiment described above. The configuration of the inkjet recording device 100 in this modified example is the same as that of the inkjet recording device 100 in the second embodiment described above.

[0051] In the control parameter correction process of this modified example shown in Figure 10, first, the control unit 40 performs steps S31 to S35, which are the same as steps S11 to S15 of the control parameter correction process of the second embodiment. Next, the control unit 40 selects waveform pattern data (control parameters) for the drive waveform to be output to each recording element 20a from the waveform setting data 51 based on the droplet velocity acquired in step S35 (step S36), and terminates the process. Specifically, as shown in Figure 11, the control unit 40 selects waveform A, which has a low voltage value, when the droplet velocity is slower than the target value, which represents a state without concentration unevenness. The control unit 40 also selects waveform C, which has a high voltage value, when the droplet velocity is faster than the target value. Furthermore, the control unit 40 selects waveform B, which has a voltage value between waveform A and waveform C, when the droplet velocity is appropriate for the target value.

[0052] In this way, by selecting the waveform pattern data of the drive waveform based on the droplet velocity, it is possible to reduce the deviation in the impact position before and after switching the waveform pattern. In step S36 of the control parameter correction process for the modified example 2 of the second embodiment described above, the voltage value of the drive waveform is changed by selecting waveform pattern data of the drive waveform based on the droplet velocity, but this is not limited to this. The pulse width and slope time of the drive waveform may also be changed. Furthermore, a complex waveform other than a single-pulse waveform may be used for the waveform shape. Furthermore, the number of waveform pattern data for the drive waveform stored in the waveform setting data 51 is determined by the highest frequency of the image forming job, the input image data transfer speed, the number of gradations of ink volume, etc.

[0053] (Variation 3) Next, a third modified example of the second embodiment described above will be explained. Figure 12 is a flowchart showing the control parameter correction process for this modified example. The control unit 40 performs the control parameter correction process for this modified example while the inkjet head 20 is forming an image. The following will focus on explaining the differences from the second embodiment described above. The configuration of the inkjet recording device 100 in this modified example is the same as that of the inkjet recording device 100 in the second embodiment described above.

[0054] In the control parameter correction process of this modified example shown in Figure 12, first, the control unit 40 performs steps S41 to S45, which are the same as steps S11 to S15 of the control parameter correction process of the second embodiment. Next, the control unit 40 controls the robot arm drive control unit 12 based on the droplet velocity acquired in step S45, and changes at least one of the position and angle of the carriage 111 (step S46), and then terminates the process. Specifically, if the droplet velocity is slower than the target value (predetermined reference value) for a state without concentration unevenness, the control unit 40 reduces the distance (control parameter) between the carriage 111 and the recording medium. Conversely, if the droplet velocity is faster than the target value, the control unit 40 increases the distance (control parameter) between the carriage 111 and the recording medium. Furthermore, if the droplet velocity is slower than the target value, the control unit 40 corrects the angle (control parameter) of the carriage 111 so that the droplets land close together. Also, if the droplet velocity is faster than the target value, the control unit 40 corrects the angle (control parameter) of the carriage 111 so that the droplets land sparsely. In the second embodiment and its modified form, the control unit 40 may obtain the acceleration of the carriage 111 at the pixel corresponding to the current position of 111 from the detection unit 111a, and perform control parameter correction processing based on the acceleration of the carriage 111.

[0055] As described above, the inkjet recording device 100 of this embodiment includes an inkjet head 20, a carriage 111 on which the inkjet head 20 is mounted, a setting unit (control unit 40) that sets at least one of the speed and acceleration of the carriage 111 for each position of the carriage 111, an acquisition unit (control unit 40) that acquires information on the drive cycle dependence of the droplet velocity of the ink ejected from the inkjet head 20, and a correction unit (control unit 40) that corrects the control parameters of the ink ejection of the inkjet head 20 based on at least one of the speed and acceleration of the carriage and the drive cycle dependence information of the droplet velocity. Therefore, more stable image quality can be obtained in the resulting image.

[0056] Furthermore, the inkjet recording apparatus 100 of this embodiment includes an inkjet head 20, a carriage 111 on which the inkjet head 20 is mounted, a detection unit 111a that detects at least one of the speed and acceleration of the carriage 111 for each pixel of the image to be formed, an acquisition unit (control unit 40) that acquires information on the drive cycle dependence of the droplet velocity of the ink ejected from the inkjet head 20, and a correction unit (control unit 40) that corrects the control parameters of the ink ejection of the inkjet head 20 based on at least one of the speed and acceleration of the carriage 111 and the drive cycle dependence information of the droplet velocity. Therefore, more stable image quality can be obtained in the resulting image.

[0057] Furthermore, the inkjet recording device 100 of this embodiment includes an inkjet head 20, a carriage 111 on which the inkjet head 20 is mounted, a setting unit (control unit 40) that sets at least one of the carriage speed and acceleration for each position of the carriage 111, a detection unit 111a that detects at least one of the carriage speed and acceleration for each pixel of the image to be formed, an acquisition unit (control unit 40) that acquires information on the drive cycle dependence of the ink droplet speed ejected from the inkjet head 20, and a correction unit (control unit 40) that corrects the control parameters of the ink ejection of the inkjet head 20 based on at least one of the carriage speed and acceleration and the drive cycle dependence information of the droplet speed. Therefore, more stable image quality can be obtained in the resulting image.

[0058] Furthermore, the inkjet recording device 100 of this embodiment is equipped with a detection unit 111a on the inkjet head 20 or the carriage 111. Therefore, the speed and acceleration of the inkjet head 20 can be detected more accurately than when the detection unit 111a is located on a part of the robot arm body 11 other than the carriage 111.

[0059] Furthermore, in the inkjet recording apparatus 100 of this embodiment, the correction unit corrects the control parameters when the speed of the carriage 111 is not constant. Therefore, even if the carriage 111 is not moving at a constant speed, more stable image quality can be obtained in the formed image.

[0060] Furthermore, the inkjet recording apparatus 100 of this embodiment uses three-dimensional objects as the object of image formation. Therefore, even when the recording medium is a three-dimensional object, more stable image quality can be obtained in the resulting image.

[0061] Furthermore, in the inkjet recording apparatus 100 of this embodiment, the correction unit corrects the image data as a control parameter. Therefore, by correcting the image data, more stable image quality can be obtained in the resulting image.

[0062] Furthermore, in the inkjet recording apparatus 100 of this embodiment, the correction unit corrects the ejection signal as a control parameter. Therefore, by correcting the output signal, more stable image quality can be obtained in the formed image.

[0063] Furthermore, in the inkjet recording apparatus 100 of this embodiment, the correction unit performs the correction by selecting the drive waveform as a control parameter. Therefore, by correcting the drive waveform, more stable image quality can be obtained in the resulting image.

[0064] Furthermore, in the inkjet recording apparatus 100 of this embodiment, the correction unit corrects the distance between the inkjet head 20 and the recording medium and the angle of the inkjet head 20 with respect to the recording medium as control parameters. Therefore, by correcting the distance and angle of the inkjet head 20 relative to the recording medium, more stable image quality can be obtained in the formed image.

[0065] Furthermore, in the inkjet recording apparatus 100 of this embodiment, the correction unit corrects the distance between the inkjet head 20 and the recording medium in a direction that widens the distance when the droplet velocity is faster than a predetermined reference value, and corrects the distance in a direction that narrows the distance when the droplet velocity is slower than a predetermined reference value. Therefore, by correcting the distance of the inkjet head 20 to the recording medium based on the droplet velocity, more stable image quality can be obtained in the formed image.

[0066] Furthermore, in the inkjet recording apparatus 100 of this embodiment, the correction unit corrects the angle of the inkjet head 20 with respect to the recording medium so that when the droplet velocity is faster than a predetermined reference value, the landing positions of the droplets ejected from the inkjet head 20 are sparse, and when the droplet velocity is slower than a predetermined reference value, the landing positions of the droplets ejected from the inkjet head 20 are dense. Therefore, by correcting the angle of the inkjet head 20 relative to the recording medium based on the droplet velocity, more stable image quality can be obtained in the formed image.

[0067] Furthermore, the inkjet recording device 100 of this embodiment includes a robot arm (robot arm body 11), and the robot arm includes a carriage 111. Therefore, even if the carriage 111 is mounted on the robot arm and the speed of the carriage 111 is not constant, more stable image quality can be obtained in the formed image.

[0068] It should be noted that the present invention is not limited to the embodiments and modifications described above, and various modifications are possible. For example, in the above embodiments and modifications, the inkjet recording device 100 is provided with a robot arm body 11 on which an inkjet head 20 is mounted, but it is not limited to this. In a configuration in which the inkjet head 20 is mounted on a carriage that moves on rails, the control parameters for ink ejection of the inkjet head 20 may be corrected when image formation is performed when the carriage's movement speed is not constant.

[0069] Furthermore, while the above embodiments and modifications show examples of correction when the carriage speed is not constant, the invention is not limited to these examples. Correction may also be applied when the carriage speed is constant but the drive frequency of the inkjet head changes.

[0070] Furthermore, in the above embodiments and modifications, the speed and acceleration of the carriage 111 are detected by a detection unit provided on the inkjet head 20 or the carriage 111, but this is not limited to this. They may also be detected based on the output signal of the encoder 121 of the robot arm drive control unit 12.

[0071] Furthermore, the control unit 40 may also use the correction of control parameters for ink ejection of the inkjet head 20 in the control parameter correction process of the first and second embodiments described above.

[0072] Furthermore, specific details such as the configuration of the inkjet recording apparatus 100 shown in the above embodiments can be modified as appropriate without departing from the spirit of the present invention. The scope of the present invention includes the scope of the invention described in the claims and its equivalents. [Industrial applicability]

[0073] This invention can be used in inkjet recording devices and programs. [Explanation of Symbols]

[0074] 100 Inkjet Recording Devices 10 Robot arm section 11. Robot arm body 111 Carriage 111a Detection unit 12 Robot arm drive control unit 20 inkjet heads 20a recording element 21 nozzles 22 Ink channel 23 Piezoelectric element 24 Head drive unit 30 Drive waveform signal generation unit 40 Control Unit 41 CPU 42 RAM 50 Storage section 51 Waveform setting data 60 Communications Department 71 Operation Reception Section 72 Display section 80 Power supply section

Claims

1. An inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. Equipped with, The correction unit calculates a grayscale profile showing the correspondence between the position of the carriage and the density of the formed image based on at least one of the carriage's speed and acceleration, and information on the drive cycle dependence of the droplet speed, and corrects the control parameters of the ink ejection of the inkjet head to cancel out density unevenness in the grayscale profile.

2. Inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. Equipped with, The correction unit is an inkjet recording apparatus that corrects the control parameters when the carriage speed is not constant.

3. Inkjet head and A carriage equipped with the aforementioned inkjet head, A detection unit that detects at least one of the carriage's velocity and acceleration for each pixel of the image to be formed, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. An inkjet recording device equipped with the following features.

4. Inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, A detection unit that detects at least one of the carriage's velocity and acceleration for each pixel of the image to be formed, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. An inkjet recording device equipped with the following features.

5. The inkjet recording apparatus according to claim 3 or 4, wherein the detection unit is provided in the inkjet head or the carriage.

6. The inkjet recording apparatus according to claim 3 or 4, wherein the correction unit corrects the control parameters when the carriage speed is not constant.

7. An inkjet recording apparatus according to any one of claims 2 to 4, wherein a three-dimensional object is used as the object for image formation.

8. The inkjet recording apparatus according to any one of claims 2 to 4, wherein the correction unit corrects image data as a control parameter.

9. The inkjet recording apparatus according to any one of claims 2 to 4, wherein the correction unit corrects the ejection signal as a control parameter.

10. The inkjet recording apparatus according to any one of claims 2 to 4, wherein the correction unit corrects by selecting a drive waveform as a control parameter.

11. The inkjet recording apparatus according to claim 3 or 4, wherein the correction unit corrects the distance between the inkjet head and the recording medium and the angle of the inkjet head with respect to the recording medium as control parameters.

12. An inkjet head and A carriage equipped with the aforementioned inkjet head, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage, An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head, A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. Equipped with, The correction unit corrects the distance between the inkjet head and the recording medium and the angle of the inkjet head relative to the recording medium as control parameters in an inkjet recording apparatus.

13. The inkjet recording apparatus according to claim 11, wherein the correction unit corrects the distance between the inkjet head and the recording medium in a direction that widens the distance when the droplet velocity is faster than a predetermined reference value, and corrects the distance in a direction that narrows the distance when the droplet velocity is slower than a predetermined reference value.

14. The inkjet recording apparatus according to claim 11, wherein the correction unit corrects the angle of the inkjet head with respect to the recording medium so that the landing positions of droplets ejected from the inkjet head are sparse when the droplet velocity is faster than a predetermined reference value, and corrects the landing positions of droplets ejected from the inkjet head are dense when the droplet velocity is slower than a predetermined reference value.

15. Equipped with a robotic arm, The inkjet recording apparatus according to any one of claims 2 to 4, wherein the robot arm comprises the carriage.

16. Inkjet head and A carriage equipped with the aforementioned inkjet head, A computer for an inkjet recording device equipped with, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage. An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head. A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. To make it function as, The correction unit is a program that corrects the control parameters when the carriage speed is not constant.

17. An inkjet head and A carriage equipped with the aforementioned inkjet head, A computer for an inkjet recording device equipped with, A setting unit that sets at least one of the carriage speed and acceleration for each position of the carriage. An acquisition unit that acquires information on the drive cycle dependence of the ink droplet velocity ejected from the inkjet head. A correction unit corrects the control parameters of the ink ejection of the inkjet head based on at least one of the carriage speed and acceleration, and the drive cycle dependency information of the droplet speed. To make it function as, The correction unit is a program that corrects the distance between the inkjet head and the recording medium and the angle of the inkjet head relative to the recording medium as control parameters.

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