Printing apparatus and printing method

Abstract

To provide a printer and a printing method which can reduce variation in printing quality than a conventional device and method.SOLUTION: A waveform DB230 for holding a plurality of waveform data indicating waveforms of each of a plurality of driving signals SD is provided. In a control part 150, each printing job is associated with the waveform data, and a waveform number WN for specifying the waveform data is transmitted from the control part 150 to a head control part 210. The head control part 210 transfers the waveform number WN transmitted from the control part 150 to a head drive substrate 220, for each of the printing jobs. The head drive substrate 220 takes out the waveform data corresponding to the waveform number WN transferred from the head control part 210 from the waveform DB230 for each of the printing jobs, and gives the driving signals SD of the waveforms according to the taken out waveform data to an inkjet head 241.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a printing apparatus including a head that discharges ink in response to a drive signal.

Background Art

[0002] Conventionally, an inkjet printing apparatus (hereinafter referred to as an "inkjet printer") that performs printing by ejecting ink toward a printing medium (typically, printing paper) by heat or pressure has been known. In a drop-on-demand inkjet printer, for example, ink is ejected by mechanical pressure using a piezo element. Regarding such an inkjet printer, a head (hereinafter referred to as an "inkjet head"), which is a mechanism for discharging ink onto a printing medium, is provided with a large number of nozzles that are ink discharge ports. In an inkjet printer using a piezo element, a piezo element is provided corresponding to each nozzle, and the ink inside the ink chamber adjacent to the nozzle is pressurized by the deformation of the piezo element based on a drive signal (drive voltage) having a predetermined drive waveform. As a result, ink is ejected from the nozzle toward the printing medium.

[0003] As described above, in an inkjet printer, printing on a printing medium is performed by controlling whether or not to eject ink from each nozzle by a drive signal.

[0004] In connection with the present invention, the following prior art documents are known. Japanese Patent Application Laid-Open No. 11-20158 discloses a technique for switching a drive waveform for driving a recording head according to the ambient temperature. According to that technique, the recording density is kept constant regardless of the temperature. Also, Japanese Patent Application Laid-Open No. 2004-338414 discloses a technique for analyzing the operating state of nozzles based on print data and giving a fine vibration to a meniscus according to the operating state of the nozzles. According to that technique, an increase in ink viscosity is prevented and the flight of ink droplets is stabilized.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-20158 [Patent Document 2] Japanese Patent Publication No. 2004-338414 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Incidentally, improving print quality has long been a challenge for inkjet printing equipment. For example, depending on the print density of the print job being executed, the drying unit (heater, etc.) may not be able to dry the printed paper in time, or the ink supply to the inkjet head may not be able to keep up. When drying by the drying unit or ink supply is not fast enough, it is not possible to obtain prints of sufficient quality. Also, print quality may vary depending on the type of print, for example, sufficient quality may be obtained for text prints, but not for image prints. As described above, with conventional inkjet printing equipment, print quality can vary depending on the attributes of the print job.

[0007] Furthermore, the technology disclosed in Japanese Patent Publication No. 11-20158 or the technology disclosed in Japanese Patent Publication No. 2004-338414 cannot suppress the occurrence of variations in print quality caused by differences in the attributes of print jobs.

[0008] In view of the above circumstances, the present invention aims to provide a printing apparatus and a printing method that can reduce variations in print quality compared to conventional methods. [Means for solving the problem]

[0009] The first invention is, Conveyed in the conveying direction A printing apparatus that performs printing by ejecting ink onto a printing medium, Includes multiple nozzles,Based on the given drive signal, for the printing medium From each of the aforementioned number of nozzles discharge ink At least one print head and Corresponding one-to-one with at least one print head, the At least one head drive board that provides a drive signal to at least one print head. and a waveform data holding unit that holds a plurality of waveform data representing the waveforms of the plurality of drive signals A print rate calculation unit calculates the print rate of each of the multiple image areas included in each print job by analyzing the print data that makes up each print job. An image type identification unit identifies the type of image for each of the multiple image regions based on the print ratio calculated by the print ratio calculation unit, each printing job Based on the image type identified by the image type identification unit, each of the multiple image regions is assigned to one of the multiple waveform data. an associating unit for associating 、 For each print job, a data transmission unit transmits job data constituting the print job, waveform identification data for identifying the plurality of waveform data, and control-related information to at least one head drive board. and is provided with Each head drive board For each printing job, the waveform data associated by the associating unit is taken out from the waveform data holding unit, and a drive signal having a waveform corresponding to the taken-out waveform data is Compatible print heads given to 、 The aforementioned plurality of image regions are regions divided in multiple directions in the transport direction and in directions intersecting the transport direction within the print area corresponding to one print job. The control-related information includes information that identifies the position of each image region, information that identifies the nozzle corresponding to each image region, and information that associates each waveform identification data with the position of each image region. characterized by this. The second invention is, in the first invention, The image type identified by the image type identification unit includes at least characters and pictures, The aforementioned association unit is, The image region in which the image type identified by the image type identification unit is a character is associated with waveform data in which no satellites are generated. The image type identified by the image type identification unit is characterized by associating the image region, which is a pattern, with waveform data that generates satellites and improves granularity.

[0021] The 3 invention of the 1 in the invention of the the At least one print head consists of a plurality of print heads the At least one head drive board includes a plurality of head drive boards that correspond one-to-one with the plurality of print heads the waveform data holding unit is provided corresponding to each of the plurality of head drive boards The waveform data holding unit provided corresponding to each head drive board holds a plurality of waveform data corresponding to the corresponding print head, which is characterized by this.

[0022] The 4The invention of 3 In the invention of the waveform data holding unit is a memory attached to the corresponding head drive board, which is characterized in that.

[0023] The 5 invention of 1 in the invention of the At least one print head consists of a plurality of print heads, the At least one head drive board includes a plurality of head drive boards corresponding to the plurality of print heads one-to-one, the waveform data holding unit is provided in common to the plurality of head drive boards, which is characterized in that.

[0024] The 6 invention of 1 in the invention of Each head drive board includes a waveform data correction unit that generates drive waveform data by correcting the waveform data taken out from the waveform data holding unit, the drive signal of the waveform represented by the drive waveform data is Each print head applied to, which is characterized in that.

[0025] The 7 invention of 6 in the invention of the waveform data correction unit generates the drive waveform data by multiplying the waveform data taken out from the waveform data holding unit by a predetermined gain, which is characterized in that.

[0026] The 8 invention of 7 in the invention of the At least one print head consists of a plurality of print heads each including a plurality of nozzles, the value of the gain is determined for each nozzle or each print head, which is characterized in that.

[0027] The 9 invention of 1 in the invention of The printing apparatus further comprises a transport mechanism for transporting the printing medium, The aforementioned At least one print head teeth, The aforementioned transport direction The first is arranged in a direction perpendicular to the first Printhead group and the second Printhead group Includes, The first Printhead group Ink ejection from and the second Printhead group The ink ejection from the machine is characterized by being performed based on different print jobs.

[0028] The 10 The invention is Includes multiple nozzles, Based on the given drive signal, for the printing medium From each of the aforementioned number of nozzles Dispense ink At least one print head, and a one-to-one correspondence with the said at least one print head, The aforementioned A head drive board that provides a drive signal to at least one print head, and a waveform data holding unit that holds multiple waveform data representing the waveforms of multiple drive signals. A printing method in a printing apparatus equipped with, A print rate calculation step that calculates the print rate of each of the multiple image areas included in each print job by analyzing the print data that makes up each print job, An image type identification step that identifies the image type of each of the multiple image regions based on the print rate calculated in the print rate calculation step, Each print job Based on the image type identified in the image type identification step, each of the plurality of image regions is selected from among the plurality of waveform data. The association step to associate with, A data transmission step for each print job, which transmits job data constituting the print job, waveform identification data for identifying the plurality of waveform data, and control-related information to at least one head drive board, The aforementioned At least one print head Discharge control step that provides a drive signal to and Includes, In the ejection control step, for each print job, the waveform data associated in the association step is retrieved from the waveform data holding unit, and a waveform drive signal corresponding to the retrieved waveform data is generated. At least one print head Given to 、 The aforementioned plurality of image regions are regions divided in the transport direction in which the printing medium is transported and in directions intersecting the transport direction within the printing region corresponding to one print job. The control-related information includes information that identifies the position of each image region, information that identifies the nozzle corresponding to each image region, and information that associates each waveform identification data with the position of each image region. It is characterized by the following: [Effects of the Invention]

[0029] According to the first invention described above, the inkjet printing apparatus ejects ink Print head A waveform data holding unit is provided that holds multiple waveform data representing the waveforms of each of the multiple drive signals to be supplied. Each of the multiple image regions contained within is The association unit, Based on the type of imageAmong multiple waveform data either It is associated with each print job. Each of the multiple image regions included Regarding this, the waveform data associated by the association unit is retrieved from the waveform data holding unit, and based on the waveform drive signal corresponding to the retrieved waveform data, Print head Ink is ejected from there. Therefore, This suppresses variations in print quality depending on the type of printed material, and also makes it possible to reduce variations in print quality between multiple image areas compared to conventional methods.

[0041] The above 3 According to this invention, compared to the case where a common waveform data holding unit is provided for multiple head drive boards, the time required to access the data in the waveform data holding unit from each head drive board is reduced. As a result, processing time is shortened.

[0042] The above 4 According to the invention, the above-mentioned 3 The same effect as the previous invention can be obtained.

[0043] The above 5 According to this invention, the increase in circuit size due to the provision of a waveform data holding unit is suppressed.

[0044] The above 6 According to the invention, Print head The waveform of the drive signal supplied to the device can be finely adjusted. This makes it possible to more effectively reduce variations in print quality.

[0045] The above 7 According to this invention, it becomes possible to adjust the waveform of the drive signal relatively easily.

[0046] The above 8 According to this invention, the waveform of the drive signal can be adjusted considering the ink ejection state of each nozzle or print head. This makes it possible to reduce not only variations in print quality caused by the content of the print job, but also variations in print quality caused by differences in ink ejection state between nozzles or print heads.

[0047] The above 9According to this invention, even when multiple print jobs are executed simultaneously, each print job is associated with appropriate waveform data, making it possible to reduce variations in print quality compared to conventional methods.

[0048] The above 10 According to this invention, the same effects as the first invention described above can be obtained. [Brief explanation of the drawing]

[0049] [Figure 1] This is an overall configuration diagram of a printing system according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram showing one example of the configuration of the inkjet printing apparatus in the first embodiment described above. [Figure 3] This is a plan view showing one example of the configuration of the printing section in the first embodiment described above. [Figure 4] This is a diagram illustrating the components corresponding to one nozzle in the first embodiment described above. [Figure 5] This is a block diagram showing the hardware configuration of the print control device in the first embodiment described above. [Figure 6] This is a block diagram illustrating the configuration related to driving the inkjet head in the first embodiment described above. [Figure 7] This is a diagram illustrating the data stored in the waveform DB in the first embodiment described above. [Figure 8] This figure shows another example of the data stored in the waveform DB in the first embodiment described above. [Figure 9] This is a diagram illustrating the reference table in the first embodiment described above. [Figure 10] This is a block diagram showing the schematic functional configuration of the control unit in the first embodiment described above. [Figure 11] This flowchart shows the procedure for waveform data control processing in the first embodiment described above. [Figure 12]This figure illustrates data stored in a waveform database in a second embodiment of the present invention. [Figure 13] This is a diagram illustrating the reference table in the second embodiment described above. [Figure 14] This is a block diagram showing the schematic functional configuration of the control unit in the second embodiment described above. [Figure 15] This figure illustrates how to identify the type of image for each image region in the second embodiment described above. [Figure 16] This is a block diagram illustrating a waveform data correction unit in a third embodiment of the present invention. [Figure 17] This figure illustrates the process of multiplying waveform data by a gain in the third embodiment described above. [Figure 18] The second modified example is a block diagram illustrating the configuration related to the driving of the inkjet head. [Figure 19] This is a diagram illustrating the first ink ejection unit and the second ink ejection unit in the third modified example. [Modes for carrying out the invention]

[0050] Embodiments of the present invention will be described below with reference to the attached drawings.

[0051] <1. First Embodiment> <1.1 Overall Configuration of the Printing System> Figure 1 is an overall configuration diagram of a printing system according to the first embodiment of the present invention. This printing system consists of an inkjet printing device 10 and a print data generation device 40. The inkjet printing device 10 and the print data generation device 40 are connected to each other by a communication line 5. The print data generation device 40 generates print data by performing RIP processing on input data such as PDF files. The print data generated by the print data generation device 40 is transmitted to the inkjet printing device 10 via the communication line 5. The inkjet printing device 10 outputs a print image onto printing paper, which is the printing medium, based on the print data transmitted from the print data generation device 40, without using a printing plate. The inkjet printing device 10 consists of a printing press body 200, a printing control device 100 that controls the operation of the printing press body 200, and an image inspection device 300 that inspects the printing state. However, the present invention can also be applied to an inkjet printing device that does not have an image inspection device 300 (i.e., an inkjet printing device that does not have a function to inspect the printing state).

[0052] <1.2 Configuration of an inkjet printing device> Figure 2 is a schematic diagram showing one example configuration of an inkjet printing apparatus 10. As described above, this inkjet printing apparatus 10 is composed of a print control device 100, a printing press body 200, and an image inspection device 300.

[0053] The printing press body 200 includes a paper feeding unit 21 that supplies printing paper (e.g., roll paper) PA, a printing mechanism 20 that prints on the printing paper PA, and a paper winding unit 28 that winds up the printed printing paper PA. The printing mechanism 20 includes a first drive roller 22 for transporting the printing paper PA into the mechanism, a plurality of support rollers 23 for transporting the printing paper PA inside the printing mechanism 20, a printing unit 24 that ejects ink onto the printing paper PA to print, a cleaning mechanism 25 that cleans the printing unit 24 (e.g., sucking ink from the nozzles or wiping the nozzle surfaces), a drying unit 26 for drying the printed printing paper PA, an imaging unit 310 that captures a printed image (the printed printing paper PA), and a second drive roller 27 for outputting the printing paper PA from inside the printing mechanism 20. The imaging unit 310 is a component of the image inspection device 300 and is configured using an image sensor such as a CCD or CMOS.

[0054] The print control device 100 controls the operation of the printing press body 200 configured as described above. When the print control device 100 receives a print output command, it controls the operation of the printing press body 200 so that the printing paper PA is transported from the paper feeding unit 21 to the paper winding unit 28. First, the printing unit 24 prints on the printing paper PA, then the drying unit 26 dries the printing paper PA, and finally the imaging unit 310 captures the printed image. In addition, the cleaning mechanism 25 cleans the printing unit 24 as needed.

[0055] The image inspection device 300 consists of an imaging unit 310 and an image inspection computer 320. The image data Di obtained by imaging the printed image with the imaging unit 310 is sent to the image inspection computer 320. The image inspection computer 320 performs inspections, such as detecting defects by comparing and verifying the image data Di with the printed data Dp transmitted from the print data generation device 40. The inspection result Dr obtained by the image inspection computer 320 is then sent to the print control device 100.

[0056] In this embodiment, the transport mechanism is realized by a paper feeding unit 21, a first drive roller 22, a plurality of support rollers 23, a second drive roller 27, and a paper winding unit 28. The print control device 100 is provided with a transport control unit (not shown in Figure 2) that controls the transport speed, which is the distance that the printing paper PA is transported per unit time by the transport mechanism.

[0057] Figure 3 is a plan view showing one example of the configuration of the printing unit 24. As shown in Figure 3, the printing unit 24 consists of inkjet head rows 240C, 240M, 240Y, and 240K for C (cyan), M (magenta), Y (yellow), and K (black), arranged in the direction of transport of the printing paper PA. Each inkjet head row consists of multiple inkjet heads (print heads) 241 arranged in a staggered pattern. Each inkjet head 241 contains numerous nozzles that eject ink. Each nozzle of the inkjet head 241 in the C-color inkjet head row 240C ejects C-color ink, each nozzle of the inkjet head 241 in the M-color inkjet head row 240M ejects M-color ink, each nozzle of the inkjet head 241 in the Y-color inkjet head row 240Y ejects Y-color ink, and each nozzle of the inkjet head 241 in the K-color inkjet head row 240K ejects K-color ink.

[0058] Figure 4 is a diagram illustrating the components corresponding to one nozzle. As shown in Figure 4, corresponding to the nozzle 250, there is an ink chamber 251 where ink is stored, an ink supply passage 252 for supplying ink to the ink chamber 251, and a piezoelectric element 253 for applying pressure to the ink inside the ink chamber 251. In this configuration, when a drive signal SD having a predetermined drive waveform is applied to the piezoelectric element 253, the piezoelectric element 253 deforms based on the drive signal SD. As a result, the ink inside the ink chamber 251 is pressurized, and ink is ejected from the nozzle 250.

[0059] <1.3 Hardware configuration of the print control device> Figure 5 is a block diagram showing the hardware configuration of the print control device 100. As shown in Figure 5, the print control device 100 includes a main unit 110, an auxiliary storage device 121, an optical disc drive 122, a display unit 123, a keyboard 124, and a mouse 125. The main unit 110 includes a CPU 111, memory 112, a first disk interface unit 113, a second disk interface unit 114, a display control unit 115, an input interface unit 116, an output interface unit 117, and a network interface unit 118. The CPU 111, memory 112, first disk interface unit 113, second disk interface unit 114, display control unit 115, input interface unit 116, output interface unit 117, and network interface unit 118 are connected to each other via a system bus. The auxiliary storage device 121 is connected to the first disk interface unit 113. The optical disc drive 122 is connected to the second disk interface unit 114. The display unit (display device) 123 is connected to the display control unit 115. The input interface unit 116 is connected to a keyboard 124 and a mouse 125. The output interface unit 117 is connected to the printer body 200 via a communication cable. The network interface unit 118 is connected to a communication line 5. The auxiliary storage device 121 is a magnetic disk drive or the like. An optical disk 6, such as a CD-ROM or DVD-ROM, is inserted into the optical disk drive 122. The display unit 123 is a liquid crystal display or the like. The display unit 123 is used to display information desired by the operator. The keyboard 124 and mouse 125 are used by the operator to input instructions to this print control device 100.

[0060] The auxiliary storage device 121 stores a print control program (a program for controlling the execution of printing processes by the printing press 200) P. The CPU 111 reads the print control program P stored in the auxiliary storage device 121 into the memory 112 and executes it, thereby realizing various functions of the print control device 100. The memory 112 includes RAM and ROM. The memory 112 functions as a work area for the CPU 111 to execute the print control program P stored in the auxiliary storage device 121. The print control program P is provided stored on the above-mentioned computer-readable recording medium (non-transient recording medium). That is, the user can, for example, purchase an optical disc 6 as the recording medium for the print control program P, insert it into the optical disc drive 122, read the print control program P from the optical disc 6, and install it into the auxiliary storage device 121. Alternatively, the print control program P transmitted via the communication line 5 may be received by the network interface unit 118 and installed into the auxiliary storage device 121.

[0061] <1.4 Waveform Data Control Processing> <1.4.1 Overview> In the inkjet printing apparatus 10 according to this embodiment, waveform data control processing is performed so that a drive signal SD with a waveform (drive waveform) corresponding to the attributes of the print job is supplied to the inkjet head 241. In this embodiment, the waveform data control processing determines the waveform of the drive signal SD for each ink color according to the print density obtained based on the print data constituting the print job, and the determined waveform of the drive signal SD is supplied to the inkjet head 241.

[0062] Incidentally, the optimal transport speed (the speed at which the transport mechanism transports the printing paper PA) for drying the printed paper PA after printing (drying by the drying unit 26) varies depending on the print density. Furthermore, the waveform of the drive signal SD needs to be switched depending on whether printing is performed at a high transport speed or a low transport speed. Therefore, in this embodiment, waveform data for the drive signal SD corresponding to a high transport speed and waveform data for the drive signal SD corresponding to a low transport speed are prepared in advance for each ink color, and the drive signal SD generated by the waveform data selected according to the print density for each ink color is supplied to the inkjet head 241.

[0063] <1.4.2 Configuration related to driving the inkjet head> Figure 6 is a block diagram illustrating the configuration related to the driving of the inkjet head 241 (configuration related to waveform data control processing). It is assumed that this inkjet printing apparatus 10 is equipped with n inkjet heads 241(1) to 241(n) (where n is an integer). These n inkjet heads 241(1) to 241(n) include an inkjet head 241 for C color, an inkjet head 241 for M color, an inkjet head 241 for Y color, and an inkjet head 241 for K color.

[0064] As shown in Figure 6, the inkjet printing apparatus 10 is equipped with a control unit 150, which is realized when a print control program P is executed in the print control device 100, a head control unit (control board) 210, head drive boards 220(1) to 220(n) that correspond one-to-one with n inkjet heads 241(1) to 241(n), and a waveform DB (database) 230 as components for driving the inkjet head 241.

[0065] First, the waveform DB230 will be described. In this embodiment, the waveform DB230 is provided in common for n head drive boards 220(1) to 220(n). The waveform DB230 is implemented using memory such as ROM and is accessible from the n head drive boards 220(1) to 220(n). The waveform DB230 stores multiple waveform data representing the waveforms of multiple drive signals SD. By providing the waveform DB230 in common for n head drive boards 220(1) to 220(n) rather than providing one for each head drive board 220, the increase in circuit size caused by providing the waveform DB230 is suppressed.

[0066] Figure 7 is a diagram illustrating the data stored in the waveform DB230 in this embodiment. As can be seen from Figure 7, each record in the waveform DB230 consists of a waveform number and waveform data. That is, each waveform data is identified by the waveform number. In this embodiment, as shown in Figure 7, eight records are stored in the waveform DB230. For example, the record indicated by the arrow labeled 71 in Figure 7 has a waveform number of 2, and the waveform data represents the waveform for M color, which is suitable for high-speed printing. From Figure 7, it can be seen that two records are stored in the waveform DB230 for each ink color. More specifically, for each ink color, waveform data representing a waveform suitable for high-speed printing and waveform data representing a waveform suitable for low-speed printing are stored in the waveform DB230.

[0067] Figure 8 shows another example of data stored in the waveform DB230. As shown in Figure 8, various waveform data depending on the type of image to be printed by the execution of a print job can also be stored in the waveform DB230. For example, for the record indicated by the arrow labeled 72 in Figure 8, the waveform number is 0, and the waveform data represents a waveform that does not produce satellites (a waveform suitable for images with many characters).

[0068] Furthermore, in order to ensure that data for identifying the waveform data is transmitted from the print control device 100 to each head drive board 220 via the head control unit 210, rather than the waveform data itself, a reference table like the one shown in Figure 9 is provided, which associates ink color, transport speed, and waveform number (data for identifying the waveform data). This reference table is stored in the auxiliary storage device 121 or memory 112 of the print control device 100.

[0069] Regarding the components shown in Figure 6, the control unit 150 determines the print coverage rate for each print job by analyzing the print data, and obtains a waveform number WN to identify the waveform data used when printing each ink color by referring to the reference table described above based on the transport speed (high or low speed) determined according to the print coverage rate. Then, for each print job, the control unit 150 associates the waveform number WN and control-related information CI with the job data JD that constitutes the print job and transmits it to the head control unit 210. The control-related information CI is information necessary to properly control the waveform data. In this embodiment, since a different waveform number WN is associated with each ink color, at least information associating each waveform number WN with a number that identifies the inkjet head 241 (head number) is transmitted from the control unit 150 to the head control unit 210 as control-related information CI. As a result, for example, the drive signal generated by the waveform data identified by waveform number "2" (see Figure 7) is correctly supplied to the inkjet head 241 for M color. In addition, the job data JD includes various information necessary for printing (for example, paper size information) in addition to the print data representing the image to be printed.

[0070] The head control unit 210 receives job data JD, waveform number WN, and control-related information CI transmitted from the control unit 150 for each print job. The head control unit 210 then transfers the received data (job data JD, waveform number WN, and control-related information CI) to the n head drive boards 220(1) to 220(n) for each print job. At that time, the head control unit 210 outputs only the necessary data from the received data to each head drive board 220. In this way, the waveform number WN and control-related information CI are set on each head drive board 220.

[0071] Each head drive board 220 retrieves waveform data from the waveform DB 230 based on the set waveform number WN, and provides the inkjet head 241 with a drive signal SD of the waveform represented by the retrieved waveform data, based on the print data included in the job data JD, while referring to control-related information CI. Incidentally, each head drive board 220 stores the waveform number WN and control-related information CI in a FIFO (First in First out) manner. That is, when the print job to be executed is switched, each head drive board 220 uses the earliest stored data from the accumulated data to provide the corresponding inkjet head 241 with a drive signal SD.

[0072] As described above, each inkjet head 241 contains a number of nozzles 250 that eject ink. Also, as shown in Figure 4, an ink chamber 251, an ink supply path 252, and a piezoelectric element 253 are provided corresponding to each nozzle 250. Based on the drive signal SD supplied to the inkjet head 241 from the head drive board 220, the piezoelectric element 253 deforms, causing ink to be ejected from the nozzle 250.

[0073] In this embodiment, the waveform DB230 is used to realize the waveform data holding unit, the n inkjet heads 241(1) to 241(n) are used to realize the ink ejection unit, the head control unit 210 is used to realize the drive control unit, and the n head drive boards 220(1) to 220(n) are used to realize the drive unit. Furthermore, the head control unit 210 and the n head drive boards 220(1) to 220(n) are used to realize the ejection control unit. Waveform identification data is also realized by the waveform number WN.

[0074] <1.4.3 Functional Configuration of the Control Unit> Figure 10 is a block diagram illustrating the schematic functional configuration of the control unit 150, which is realized when the print control program P is executed in the print control device 100. However, Figure 10 only shows the components related to waveform data control processing. The control unit 150 includes an analysis unit 151, a transport speed determination unit 152, a reference table holding unit 153, a waveform number acquisition unit 154, and a data transmission unit 155. The control unit 150 is sequentially provided with multiple job data JDs corresponding to each of the multiple print jobs specified by the operator.

[0075] The analysis unit 151 determines the print density RP by analyzing the print data included in the job data JD. A known method can be used to determine the print density from the print data. The transport speed determination unit 152 determines the transport speed CS suitable for executing the print job based on the print density RP determined by the analysis unit 151. However, instead of specifying a concrete speed as the transport speed, it is determined to be either "high speed" or "low speed". In this embodiment, a threshold is set in advance, and if the print density RP is above the threshold, the transport speed CS is set to "low speed", and if the print density RP is below the threshold, the transport speed CS is set to "high speed". The reason for this setting is that if printing is performed at high speed when the print density is high, the drying unit 26 may not be able to dry the printed paper and the ink to the inkjet head 241 in time.

[0076] The reference table holding unit 153 holds the reference table RT shown in Figure 9. The waveform number acquisition unit 154 acquires the waveform number WN for each ink color by referring to the reference table RT based on the transport speed CS identified by the transport speed identification unit 152. For example, if the transport speed CS identified by the transport speed identification unit 152 is "low speed", then "1" is acquired as the waveform number WN for C color, "3" is acquired as the waveform number WN for M color, "5" is acquired as the waveform number WN for Y color, and "7" is acquired as the waveform number WN for K color. Since the transport number WN and waveform data are associated in the waveform DB 230 (see Figure 7), each print job is associated with the waveform data stored in the waveform DB 230 via the waveform number WN for each ink color. In other words, the waveform number acquisition unit 154 essentially associates each print job with one of several waveform data for each ink color.

[0077] The data transmission unit 155 transmits job data JD, waveform number WN, and control-related information CI to the head control unit 210 for each print job.

[0078] In this embodiment, the attribute acquisition unit is realized by the analysis unit 151 and the transport speed determination unit 152, the print rate calculation unit is realized by the analysis unit 151, and the association unit is realized by the waveform number acquisition unit 154.

[0079] <1.4.4 Processing Procedure> Figure 11 is a flowchart showing the procedure for waveform data control processing. Typically, this process is started when multiple print jobs to be printed are selected, and then the operator presses the print start button displayed on the display unit 123 (see Figure 5) of the print control device 100.

[0080] After the waveform data control processing begins, the print data is analyzed and the attributes of the print job are acquired based on the analysis results (step S10). Specifically, in step S10, the analysis unit 151 first analyzes the print data that constitutes the print job to be processed (specifically, the print data included in the job data JD corresponding to the print job to be processed). This determines the print density RP. Then, based on the print density RP, the transport speed determination unit 152 determines the transport speed CS. Thus, in this embodiment, the transport speed CS (high speed or low speed) is acquired as an attribute of the print job in step S10.

[0081] After step S10 is completed, the waveform number acquisition unit 154 acquires the waveform number WN by referring to the reference table RT based on the identified transport speed CS, and the acquired waveform number WN and control-related information CI are held in association with the job data JD (step S20). In this embodiment, the waveform number acquisition unit 154 acquires the waveform number WN based on the transport speed CS, but the waveform number acquisition unit 154 may also acquire the waveform number WN based on the print rate RP. That is, the print rate RP may be acquired as an attribute of the print job.

[0082] After step S20 is completed, a determination is made in step S30 to determine whether there are any print jobs for which the waveform number WN and control-related information CI have not been associated with the job data JD (in other words, print jobs for which the processing in steps S10 and S20 has not been performed). If the determination shows that there are print jobs for which the association has not been made, the process returns to step S10; otherwise, the process proceeds to step S40. The processing in steps S10 to S30 is repeated a number of times equal to the number of print jobs for which the decision to perform print output has been made.

[0083] In step S40, data corresponding to the next target of execution (print target), the print job (job data JD, waveform number WN, and control-related information CI), is transmitted from the print control device 100 to the head control unit 210.

[0084] Subsequently, the head control unit 210 transfers the data transmitted from the print control device 100 (job data JD, waveform number WN, and control-related information CI) to the head drive board 220 (step S50). However, in this embodiment, n head drive boards 220(1) to 220(n) are provided, so the corresponding data is sent to each of these n head drive boards 220(1) to 220(n). As a result, the waveform number WN and control-related information CI are set on each head drive board 220.

[0085] After step S50 is completed, each head drive board 220 retrieves waveform data from the waveform DB 230 based on the set waveform number WN, and provides the inkjet head 241 with a drive signal SD of the waveform represented by the retrieved waveform data (step S60). As a result, each inkjet head 241 ejects ink from the nozzle 250 based on the given drive signal SD.

[0086] Subsequently, a determination is made (step S70) as to whether the processing of all print jobs (processing in steps S40 to S60) has been completed. If the determination shows that there are any unprocessed print jobs, the process returns to step S40; if there are no unprocessed print jobs, this waveform data control process ends. The processing in steps S40 to S70 is repeated a number of times equal to the number of print jobs for which the decision to print output has been made.

[0087] In this embodiment, the association step is realized in step S20, and the discharge control step is realized in step S60.

[0088] Here, we assume that two print jobs (Job X and Job Y) are selected as the print jobs to be executed, that the print density RP of Job X is above a threshold, and that the print density RP of Job Y is below a threshold. In this case, when Job X is executed, the inkjet heads 241 for C color, M color, Y color, and K color are each provided with a waveform drive signal SD generated by waveform data identified by waveform numbers "1", "3", "5", and "7", respectively. When Job Y is executed, the inkjet heads 241 for C color, M color, Y color, and K color are each provided with a waveform drive signal SD generated by waveform data identified by waveform numbers "0", "2", "4", and "6", respectively. In this way, each inkjet head 241 is provided with a waveform drive signal SD suitable for printing, according to the print density RP of the print job.

[0089] In this embodiment, each print job is associated with one of a plurality of waveform data for each ink color. In this regard, the control unit 150 may also be configured to associate each print job with one of a plurality of waveform data for each inkjet head 241. In this case, the n head drive boards 220(1) to 220(n) each provide the inkjet heads 241(1) to 241(n) with a waveform drive signal SD corresponding to the waveform data associated by the control unit 150. Alternatively, the control unit 150 may also be configured to associate each print job with one of a plurality of waveform data for each nozzle 250. In this case, each inkjet head 241 is provided with a plurality of drive signals SD corresponding to each of the plurality of nozzles 250 it contains, so that ink is ejected from each nozzle 250 based on the waveform drive signal SD corresponding to the waveform data associated by the control unit 150. By associating waveform data for each nozzle 250 in this way, it is possible to reduce variations in print quality between multiple print jobs and to improve the print quality of individual printed materials.

[0090] <1.5 Effects> According to this embodiment, the inkjet printing apparatus 10 is provided with a waveform DB 230 that holds multiple waveform data representing the waveforms of multiple drive signals SD for driving the inkjet head 241. Furthermore, for each print job, the print density RP is determined based on the print data, and a transport speed CS suitable for printing is identified from the print density RP. Then, the waveform data associated with the identified transport speed CS is retrieved from the waveform DB 230, and ink is ejected from each nozzle 250 of the inkjet head 241 based on the drive signals SD generated by the retrieved waveform data. Specifically, if the print density RP is above a threshold, the transport speed CS is set to a low speed, and ink is ejected from each nozzle 250 based on a drive signal SD with a waveform suitable for low-speed printing. If the print density RP is below the threshold, the transport speed CS is set to a high speed, and ink is ejected from each nozzle 250 based on a drive signal SD with a waveform suitable for high-speed printing. As a result, regardless of the print density RP of the print job, a decrease in print quality caused by insufficient drying of the printed paper by the drying unit 26 or insufficient ink supply to the inkjet head 241 is suppressed. In other words, regardless of the print density RP of the print job, prints of sufficient quality can be obtained. As a result, the need for reprinting is reduced compared to conventional methods, making it possible to reduce the consumption of printing paper PA and ink. In this way, it can contribute to achieving the SDGs (Sustainable Development Goals). As described above, according to this embodiment, an inkjet printing apparatus 10 is realized that can reduce the variation in print quality compared to conventional methods.

[0091] <2. Second Embodiment> <2.1 Overview> In the first embodiment described above, the waveform of the drive signal SD supplied to the inkjet head 241 during printing was determined for each ink color based on the print job's print density RP (more specifically, based on whether the transport speed CS, which is determined according to the print job's print density RP, is high or low). In contrast, in this embodiment, the waveform of the drive signal SD supplied to the inkjet head 241 during printing is determined for each image area based on the content of the image to be printed by the execution of the print job. The following describes the main differences from the first embodiment described above.

[0092] <2.2 Structure> Figure 12 is a diagram illustrating the data stored in the waveform DB230 in this embodiment. The waveform DB230 in this embodiment stores waveform data representing waveforms suitable for printing for each type of image to be printed by the execution of a print job. Similar to the first embodiment described above, each record in the waveform DB230 consists of a waveform number and waveform data. For example, for the record indicated by the arrow labeled 74 in Figure 12, the waveform number is 1, and the waveform data represents a waveform suitable for printing lines.

[0093] Figure 13 is a diagram illustrating the reference table in this embodiment. As can be seen from Figure 13, this reference table associates image types with waveform numbers.

[0094] Figure 14 is a block diagram illustrating the schematic functional configuration of the control unit 150 in this embodiment. In this embodiment, the control unit 150 includes an image type identification unit 156 in place of the transport speed identification unit 152 in the first embodiment.

[0095] The analysis unit 151, similar to the first embodiment described above, determines the print density RP by analyzing the print data included in the job data JD. The image type identification unit 156 identifies the image type TY for each image area based on the print density RP determined by the analysis unit 151. The reference table holding unit 153 holds the reference table RT shown in Figure 13. The waveform number acquisition unit 154 acquires the waveform number WN for each image area by referring to the reference table RT based on the image type TY identified by the image type identification unit 156. For example, if the image type TY identified by the image type identification unit 156 for a certain image area is "pattern", then "2" is acquired as the waveform number WN. The data transmission unit 155 transmits the job data JD, waveform number WN, and control-related information CI to the head control unit 210 for each print job. In this embodiment, information identifying the position of each image region, information identifying the nozzle 250 corresponding to each image region, and information associating each waveform number WN with the position of the image region are transmitted to the head control unit 210 as control-related information CI.

[0096] Here, with reference to Figure 15, we will explain how to identify the image type TY for each image area. In Figure 15, we assume that the area labeled with reference numeral 60 is the print area corresponding to one print job. We also assume that the print area is divided into five image areas 601 to 605 based on the print data that constitutes the print job. In this case, for each of the five image areas 601 to 605, the image type TY is identified based on the print density of the area. As a result of identifying the image type TY, for example, if the image type of image area 601 is text, the image type of image area 602 is a picture, the image type of image area 603 is text, the image type of image area 604 is a line, and the image type of image area 605 is a picture, then waveform number "0" is associated with image area 601, waveform number "2" is associated with image area 602, waveform number "0" is associated with image area 603, waveform number "1" is associated with image area 604, and waveform number "2" is associated with image area 605.

[0097] <2.3 Waveform Data Control Processing> Referring to Figure 11, the procedure for waveform data control processing in this embodiment will be described. After the start of waveform data control processing, the print data is analyzed and the attributes of the print job are obtained based on the analysis results (step S10). In this embodiment, the type TY of the image (the image represented by printing based on the print data) for each image area is obtained as an attribute of the print job based on the print density RP as the result of the analysis of the print data.

[0098] After step S10 is completed, for each image region, the waveform number acquisition unit 154 acquires a waveform number WN by referring to the reference table RT based on the image type TY, and the acquired waveform number WN and control-related information CI are held in association with the job data JD (step S20). Steps S30 and S40 are the same as in the first embodiment described above.

[0099] After step S40 is completed, the head control unit 210 transfers the data transmitted from the print control device 100 (job data JD, waveform number WN, and control-related information CI) to the head drive board 220 (step S50). In this regard, in the first embodiment described above, one waveform number WN was sent to one head drive board 220 for each print job. In contrast, in this embodiment, multiple waveform numbers WN may be sent to one head drive board 220 for each print job. For example, if the area from which ink is ejected from an inkjet head 241 corresponding to a particular head drive board 220 is divided into three image areas from which different types of images are printed, then three waveform numbers WN are transmitted from the head control unit 210 to the head drive board 220. In addition, information identifying which of the three waveform numbers WN each nozzle corresponds to is transmitted from the head control unit 210 to the head drive board 220 as control-related information CI.

[0100] After step S50 is completed, each head drive board 220 retrieves waveform data from the waveform DB 230 based on the set waveform number WN for each image area, and provides the inkjet head 241 with a waveform drive signal SD represented by the retrieved waveform data (step S60). As a result, each inkjet head 241 ejects ink from the nozzle 250 based on the given drive signal SD for each image area. Step S70 is the same as in the first embodiment described above.

[0101] Here, with respect to Figure 15, as described above, we assume that the image type TY of image area 601 is characters, the image type TY of image area 602 is a pattern, the image type TY of image area 603 is characters, the image type TY of image area 604 is lines, and the image type TY of image area 605 is a pattern. In this case, when printing is performed on image area 601, the corresponding inkjet head 241 is given a drive signal SD with a waveform suitable for printing characters; when printing is performed on image area 602, the corresponding inkjet head 241 is given a drive signal SD with a waveform suitable for printing patterns; when printing is performed on image area 603, the corresponding inkjet head 241 is given a drive signal SD with a waveform suitable for printing characters; when printing is performed on image area 604, the corresponding inkjet head 241 is given a drive signal SD with a waveform suitable for printing lines; and when printing is performed on image area 605, the corresponding inkjet head 241 is given a drive signal SD with a waveform suitable for printing patterns. In this way, each inkjet head 241 is provided with a drive signal SD with a waveform suitable for printing, according to the type of image to be printed TY.

[0102] In this embodiment, waveform data is prepared for each type of image, but it is also possible to prepare waveform data for each ink color and each type of image. In this case, four inkjet heads 241 of different colors that print on a certain image area are supplied with drive signals SD with different waveforms.

[0103] <2.4 Effects> According to this embodiment, for each print job, the print density RP is determined based on the print data, and the image type TY is identified for each image area from the print density RP. Then, waveform data associated with the identified image type TY is retrieved from the waveform DB230, and ink is ejected from each nozzle 250 of the inkjet head 241 based on the drive signal SD generated by the retrieved waveform data. This makes it possible to optimize the image quality for each image type TY. In other words, changes in print quality depending on the image type TY are suppressed. As described above, according to this embodiment, an inkjet printing apparatus 10 is realized that can reduce variations in print quality compared to conventional methods, similar to the first embodiment.

[0104] <3. Third Embodiment> <3.1 Overview> In this embodiment, a waveform data correction unit is provided to correct the waveform data stored in the waveform DB230 in order to finely adjust the waveform of the drive signal SD supplied to the inkjet head 241. The drive signal SD represented by the waveform data corrected by the waveform data correction unit is then supplied to the inkjet head 241.

[0105] <3.2 Configuration and Operation> In this embodiment, as shown in Figure 16, a waveform data correction unit 222 is provided on each head drive board 220. Other aspects are the same as in the first embodiment described above. The waveform data correction unit 222 generates drive waveform data representing the waveform of the drive signal SD actually supplied to the inkjet head 241 by correcting the waveform data extracted from the waveform DB 230. This correction by the waveform data correction unit 222 is performed by multiplying the waveform data extracted from the waveform DB 230 by a predetermined gain. In this embodiment, the gain value is predetermined for each inkjet head 241, taking into account the ink ejection state from each inkjet head 241. On each head drive board 220, waveform data is extracted from the waveform DB 230 based on the waveform number WN sent from the head control unit 210. The waveform data correction unit 222 then generates drive waveform data by multiplying the extracted waveform data by a gain. The head drive board 220 supplies the inkjet head 241 with the drive signal SD represented by the generated drive waveform data. For example, let's assume that the drive waveform based on the waveform data extracted from the waveform DB230 is the waveform labeled 81 in Figure 17. In this case, if the gain value is 1.1, a drive signal SD having the drive waveform labeled 82 in Figure 17 is supplied from the head drive board 220 to the inkjet head 241, and if the gain value is 1.2, a drive signal SD having the drive waveform labeled 83 in Figure 17 is supplied from the head drive board 220 to the inkjet head 241. By using gain in this way, it becomes possible to adjust the waveform of the drive signal SD relatively easily.

[0106] While this explanation uses an example where the gain value is predetermined for each inkjet head 241, it is not limited to this. For example, the gain value could be predetermined for each nozzle 250.

[0107] <3.3 Effects> According to this embodiment, the waveform of the drive signal SD supplied to the inkjet head 241 can be adjusted more precisely. This makes it possible to more effectively reduce variations in print quality. Furthermore, by adjusting the waveform of the drive signal SD while considering the ink ejection state of each inkjet head 241, variations in print quality caused not only by the content of the print job but also by differences in ink ejection states among multiple inkjet heads 241 are reduced.

[0108] <4. Variation> The following describes some variations.

[0109] <4.1 First variation> As a first modification, we will describe an example in which the control unit 150 acquires ink consumption (the amount of ink expected to be consumed by printing based on the print data) as an attribute of the print job. Generally, the more ink consumed by executing a print job, the higher the possibility that the drying unit 26 will not be able to dry the printed paper in time, or that the supply of ink to the inkjet head 241 will not be able to keep up. Therefore, by associating each print job with waveform data based on ink consumption, as in this modification, it is possible to reduce variations in print quality.

[0110] Here, we will explain an example of how to calculate ink consumption (ink consumption for one ink color). In this example, we assume that there are three sizes (S, M, and L) for the dot size during ink ejection. In this case, the occurrence rate of S, M, and L sizes is determined for each grayscale value. This occurrence rate information is stored, for example, in the form of a table. The amount of ink droplets corresponding to each dot size is determined in advance. Here, the amount of ink droplets corresponding to S size is represented as P(S), the amount of ink droplets corresponding to M size is represented as P(M), and the amount of ink droplets corresponding to L size is represented as P(L).

[0111] The ink consumption for a single pixel is determined as follows. First, the occurrence rates of S, M, and L sizes are obtained based on the grayscale value of the pixel in question. Here, the occurrence rate of S size is denoted as R(S), the occurrence rate of M size as R(M), and the occurrence rate of L size as R(L). Then, the ink consumption Q for the pixel in question is calculated by the following equation (1). Q=P(S)×R(S)+P(M)×R(M)+P(L)×R(L) (1)

[0112] Based on equation (1) above, the ink consumption for each pixel is calculated, and then the sum of all the calculated ink consumptions is found to obtain the ink consumption for a single ink color when a print job is executed.

[0113] As described above, ink consumption can be determined, and based on this, each print job can be associated with one or more waveform data from among the multiple waveform data stored in the waveform DB230.

[0114] <4.2 Second variation> In each of the embodiments described above, as shown in Figure 6, the waveform DB230 was provided in common for n head drive boards 220(1) to 220(n). That is, one waveform DB230 was provided. However, the present invention is not limited thereto. In this modified example, as shown in Figure 18, n waveform DB230(1) to 230(n) are provided so that there is a one-to-one correspondence between the n head drive boards 220(1) to 220(n). That is, a waveform DB230 is provided for each head drive board 220. In this configuration, each waveform DB230 is realized, for example, by a memory attached to the corresponding head drive board 220.

[0115] In this modified example, each waveform DB230 stores multiple waveform data corresponding to the corresponding inkjet head 241. For example, the waveform DB230 corresponding to the head drive board 220 for driving the inkjet head 241 included in the C-color inkjet head row 240C (see Figure 3) stores multiple waveform data, including data representing a waveform for C-color suitable for high-speed printing and data representing a waveform for C-color suitable for low-speed printing.

[0116] According to this modified configuration, compared to a configuration in which a common waveform DB230 is provided for multiple head drive boards 220 (see Figure 6), the time required for each head drive board 220 to access data in the waveform DB230 is reduced. As a result, processing time is shortened.

[0117] <4.3 Third variation> In each of the embodiments described above, it was assumed that multiple print jobs were executed sequentially one by one. However, the present invention is not limited to this. The present invention can also be applied when multiple print jobs are executed simultaneously. In this regard, an example in which two print jobs are executed simultaneously is described below as a third modification.

[0118] For the sake of simplicity, we will assume that printing is performed on the left half and the right half of the printing paper PA based on different print jobs. Therefore, in this modified example, the multiple inkjet heads 241 constituting the printing unit 24 are divided into inkjet heads 241 included in the part labeled 2401 in Figure 19 and inkjet heads 241 included in the part labeled 2402 in Figure 19. For convenience, the part labeled 2401 in Figure 19 will be referred to as the "first ink ejection unit," and the part labeled 2402 in Figure 19 will be referred to as the "second ink ejection unit." That is, the printing unit 24 includes the first ink ejection unit 2401 and the second ink ejection unit 2402, which are arranged side by side in a direction perpendicular to the transport direction of the printing paper PA. The ejection of ink from the first ink ejection unit 2401 and the ejection of ink from the second ink ejection unit 2402 are performed based on different print jobs.

[0119] Under the above premise, for example, each print job is associated with one of several waveform data stored in the waveform DB230 based on the type of main image TY that constitutes the print image. In this regard, we consider a case where two print jobs (job X and job Y) are selected as the print jobs to be executed, and printing based on job X is performed on the left half of the printing paper PA, and printing based on job Y is performed on the right half of the printing paper PA. In this case, printing based on job X is performed by the inkjet head 241 included in the first ink ejection unit 2401, and printing based on job Y is performed by the inkjet head 241 included in the second ink ejection unit 2402. Here, in this case, we assume that for job X, the type of main image TY that constitutes the print image is text, and for job Y, the type of main image TY that constitutes the print image is a picture. Furthermore, we assume that the waveform DB230 stores data as shown in Figure 12, and the reference table RT stores data as shown in Figure 13. At this time, the inkjet head 241 included in the first ink ejection unit 2401 is provided with a waveform drive signal SD generated by waveform data identified by waveform number "0", and the inkjet head 241 included in the second ink ejection unit 2402 is provided with a waveform drive signal SD generated by waveform data identified by waveform number "2". In other words, the inkjet head 241 included in the first ink ejection unit 2401 is provided with a waveform drive signal SD suitable for printing characters, and the inkjet head 241 included in the second ink ejection unit 2402 is provided with a waveform drive signal SD suitable for printing images.

[0120] As shown in the example above, when a print job that primarily prints text-based images and a print job that primarily prints images with graphic designs are executed simultaneously, sufficient print quality can be obtained for both the text-based and graphic-based images.

[0121] As described above, this modified version allows for a reduction in print quality variation compared to conventional methods, as each print job is associated with appropriate waveform data even when multiple print jobs are executed simultaneously.

[0122] <5. Others> The present invention is not limited to the above embodiments (including modifications), and can be implemented with various modifications without departing from the spirit of the invention. For example, although the above embodiment describes an example in which the printing unit 24 is composed of four inkjet head rows, the present invention can also be applied when the printing unit 24 is composed of five or more inkjet head rows. Also, for example, although the above embodiment illustrates the configuration of an inkjet printing apparatus 10 that performs color printing, the present invention can also be applied when an inkjet printing apparatus that performs monochrome printing is used. [Explanation of Symbols]

[0123] 10…Inkjet printing equipment 20…printing mechanism 24…Printing Department 26...Drying section 100…Printing control device 150... Control Unit 151…Analysis Department 152... Conveying speed specification unit 153...Reference table holding section 154...Waveform number acquisition unit 155...Data transmission unit 200... Printing machine body 210...Head Control Unit 220, 220(1)~220(n)... Head drive board 222...Waveform data correction unit 230,230(1)~230(n)…Waveform DB 241, 241(1)~241(n)... Inkjet head (print head) 250... Nozzle 253... Piezo element JD...Job Data WN... Waveform number CI…Control-related information SD...Drive signal

Claims

1. A printing apparatus that performs printing by ejecting ink onto a printing medium being transported in the transport direction, A print head comprising a plurality of nozzles, which ejects ink from each of the plurality of nozzles onto the printing medium based on a given drive signal, At least one head drive board that corresponds one-to-one with the at least one print head and provides a drive signal to the at least one print head, A waveform data holding unit that holds multiple waveform data representing the waveforms of multiple drive signals, A print rate calculation unit calculates the print rate of each of the multiple image areas included in each print job by analyzing the print data that makes up each print job. An image type identification unit identifies the type of image for each of the multiple image regions based on the print ratio calculated by the print ratio calculation unit, For each print job, an association unit associates each of the multiple image regions with one of the multiple waveform data based on the image type identified by the image type identification unit, A data transmission unit transmits job data constituting the print job, waveform identification data for identifying the plurality of waveform data, and control-related information to at least one head drive board for each print job. Equipped with, Each head drive board retrieves the waveform data associated by the association unit from the waveform data holding unit for each print job, and provides a waveform drive signal corresponding to the retrieved waveform data to the corresponding print head. The aforementioned plurality of image regions are regions divided in the transport direction and in directions intersecting the transport direction within the print area corresponding to one print job. The printing apparatus is characterized in that the control-related information includes information that identifies the position of each image region, information that identifies the nozzle corresponding to each image region, and information that associates each waveform identification data with the position of each image region.

2. The type of image identified by the image type identification unit includes at least characters and pictures, The aforementioned association unit is, The image region in which the image type identified by the image type identification unit is a character is associated with waveform data in which no satellites are generated. The printing apparatus according to claim 1, characterized in that the image region in which the image type identified by the image type identification unit is a pattern is associated with waveform data that generates satellites and improves granularity.

3. The aforementioned at least one print head consists of a plurality of print heads. The at least one head drive board includes a plurality of head drive boards that correspond one-to-one with the plurality of print heads, The waveform data holding unit is provided in accordance with each of the plurality of head drive boards, The printing apparatus according to claim 1, characterized in that a waveform data holding unit provided for each head drive board holds a plurality of waveform data corresponding to the corresponding print head.

4. The printing apparatus according to claim 3, characterized in that the waveform data holding unit is a memory attached to the corresponding head drive board.

5. The aforementioned at least one print head consists of a plurality of print heads. The at least one head drive board includes a plurality of head drive boards that correspond one-to-one with the plurality of print heads, The printing apparatus according to claim 1, characterized in that the waveform data holding unit is provided in common to the plurality of head drive boards.

6. Each head drive board includes a waveform data correction unit that generates drive waveform data by correcting the waveform data taken from the waveform data holding unit, The printing apparatus according to claim 1, characterized in that a drive signal of the waveform represented by the drive waveform data is supplied to each print head.

7. The printing apparatus according to claim 6, characterized in that the waveform data correction unit generates the drive waveform data by multiplying the waveform data extracted from the waveform data holding unit by a predetermined gain.

8. The aforementioned at least one print head consists of multiple print heads, each containing multiple nozzles. The printing apparatus according to claim 7, characterized in that the gain value is determined for each nozzle or each print head.

9. The system further comprises a transport mechanism for transporting the aforementioned printing medium, The at least one print head includes a first group of print heads and a second group of print heads arranged side by side in a direction perpendicular to the transport direction, The printing apparatus according to claim 1, characterized in that the ejection of ink from the first print head group and the ejection of ink from the second print head group are performed based on different print jobs.

10. A printing method in a printing apparatus comprising: at least one print head including a plurality of nozzles, which ejects ink from each of the plurality of nozzles to a printing medium based on a given drive signal; at least one head drive board corresponding one-to-one with the at least one print head and which provides a drive signal to the at least one print head; and a waveform data holding unit which holds a plurality of waveform data representing the waveforms of each of the plurality of drive signals, A print rate calculation step that calculates the print rate of each of the multiple image areas included in each print job by analyzing the print data that makes up each print job, An image type identification step that identifies the image type of each of the multiple image regions based on the print rate calculated in the print rate calculation step, For each print job, an association step is performed to associate each of the multiple image regions with one of the multiple waveform data based on the image type identified in the image type identification step, A data transmission step for each print job, which transmits job data constituting the print job, waveform identification data for identifying the plurality of waveform data, and control-related information to at least one head drive board, A ejection control step of providing a drive signal to at least one print head, and Includes, In the ejection control step, for each print job, the waveform data associated in the association step is retrieved from the waveform data holding unit, and a waveform drive signal corresponding to the retrieved waveform data is supplied to the at least one print head. The aforementioned plurality of image regions are regions divided in the transport direction in which the printing medium is transported and in directions intersecting the transport direction within the printing region corresponding to one print job. A printing method characterized in that the control-related information includes information that identifies the position of each image region, information that identifies the nozzle corresponding to each image region, and information that associates each waveform identification data with the position of each image region.

Images