Recording device, control method and program

Abstract

To provide a technique capable of suppressing deterioration of productivity and an increase in an amount of waste ink, controlling kogation and adjusting ink density.SOLUTION: A recording device includes: recording means for ejecting ink from a nozzle for recording by using thermal energy generated in a heat generating element; a circulation passage in which ink is circulated so as to supply the ink to the recording means and supply again the ink discharged from the recording means to the recording means; and control means that can execute first control for ejecting the ink from the nozzle for discharge and causing kogation to adhere to a protective layer covering the heat generating element and second control for ejecting the ink from the nozzle for discharge, discharging the ink from the circulation passage, supplying the ink corresponding to the discharge amount to the circulation passage and adjusting density of the ink in the circulation passage and that causes, when executing the first control and the second control continuously, the discharge of the ink in one control to be also used as the discharge of the ink in the other control.SELECTED DRAWING: Figure 19

Description

[Technical field]

[0001] The present invention relates to a recording apparatus, a control method, and a program. [Background technology]

[0002] In a recording device that ejects ink using an inkjet method, for example, the ink is ejected from a nozzle using thermal energy generated by a heating element. In such a recording device, when the heating element heats the ink, scorching due to the ink occurs on the surface of the heating element, causing a change in ejection characteristics. Patent Document 1 discloses a technology for removing the scorching that occurs.

[0003] Furthermore, when ink is ejected from a state where there is almost no kogation, kogation occurs significantly on the surface of the heating element. Therefore, the ejection characteristics change significantly and become unstable until the adhesion of the kogation settles down. Patent Document 2 discloses a technology related to aging that changes the surface of the heating element from a state where there is no kogation to a state where the surface has an appropriate amount of kogation.

[0004] Furthermore, the print head that ejects the ink is provided with a sub-heater for uniformizing the temperature. Also, in order to suppress thickening of the ink due to heating by the sub-heater, the printing device is provided with a circulation path that supplies ink to the print head while recovering ink from the print head, and circulates the ink in the circulation path. In a printing device equipped with a circulation path, fresh ink is always supplied to the nozzles that eject the ink, which promotes evaporation of the liquid components of the ink from the nozzles, resulting in an increase in the concentration of the circulating ink. Patent Document 3 discloses a technology for adjusting the concentration of the ink that has increased in the circulation path. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-214141 A [Patent Document 2] JP 2014-131867 A [Patent Document 3] JP 2018-008513 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the techniques disclosed in Patent Documents 1 and 2 are specialized only for controlling kogation, and the technique disclosed in Patent Document 3 is specialized only for adjusting the ink concentration. For this reason, simply configuring a recording apparatus to execute the techniques disclosed in Patent Documents 1 and 2 and the technique disclosed in Patent Document 3 would give rise to new concerns, such as reduced productivity due to increased downtime and an increase in the amount of wasted ink.

[0007] The present invention has been made in consideration of the above problems, and aims to provide a technique that can control kogation and adjust ink concentration while suppressing a decrease in productivity and an increase in the amount of waste ink. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, one embodiment of a recording device according to the present invention is characterized in having a recording means that uses thermal energy generated by a heating element to eject ink from a nozzle to record, a circulation path through which ink is circulated to supply ink to the recording means and to supply the ink leaving the recording means back to the recording means, a first control that ejects and discharges ink from the nozzle to cause kogation to adhere to a protective layer covering the heating element, and a second control that ejects and discharges ink from the nozzle to discharge ink from the circulation path and supplies an amount of ink corresponding to the amount ejected to the circulation path, thereby adjusting the concentration of ink in the circulation path, and a control means that, when the first control and the second control are executed consecutively, the ejection of ink in one control serves as the ejection of ink in the other control. Effect of the Invention

[0009] According to the present invention, it is possible to control kogation and adjust the ink concentration while suppressing a decrease in productivity and an increase in the amount of waste ink. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a recording apparatus. [Diagram 2] FIG. 2 is a block diagram showing the configuration of a control system of the printing apparatus. [Diagram 3] 4 is a flowchart showing the contents of image processing. [Figure 4] FIG. [Diagram 5] FIG. [Figure 6] FIG. [Figure 7] FIG. 2 is a schematic diagram of a discharge module. [Figure 8] FIG. 3 is a schematic diagram illustrating a configuration of members that configure the flow path member. [Figure 9] FIG. 4 is a diagram showing a flow path formed in a flow path member. [Figure 10] FIG. [Figure 11] FIG. 4 is a diagram showing flow paths formed in a recording element substrate. [Figure 12] FIG. 4 is a diagram showing the positional relationship between adjacent recording elements. [Figure 13] FIG. 4 is a diagram showing a configuration in the vicinity of a recording element on a recording element substrate. [Figure 14] 4A and 4B are diagrams showing an electric field generated in a pressure chamber and negatively charged particles in the pressure chamber. [Figure 15] 13 is a graph showing the relationship between the number of ejections and the ejection speed when burnt food control is executed. [Figure 16] 4 is a timing chart of a number of processes executed during recording in the recording device 10. [Figure 17] FIG. 2 is a block diagram showing a functional configuration of an engine controller. [Figure 18] 11 is a flowchart showing the contents of an acquisition process. [Figure 19]11 is a flowchart showing the process contents of a decision process. [Figure 20] 13 is a flowchart showing the process contents of an update process that is a subroutine of the decision process. [Figure 21] 10 is a flowchart showing the process contents of a determination process in another embodiment. [Figure 22] 22 is a flowchart showing the processing contents of a second update process which is a subroutine of the determination process in FIG. 21. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of a recording device, a control method, and a program will be described with reference to the accompanying drawings. Note that the following embodiment does not limit the present invention, and not all of the combinations of features described in the present embodiment are essential to the solution of the present invention. Furthermore, the positions, shapes, and the like of the components described in the embodiment are merely examples, and are not intended to limit the present invention to only those.

[0012] (First embodiment) First, a recording apparatus according to a first embodiment will be described with reference to FIGS.

[0013] <Recording device configuration> FIG. 1 is a schematic diagram of a recording device. The recording device 10 in FIG. 1 includes a feed module 12 that feeds a cut sheet-like recording medium, and a recording module 14 that records on the recording medium fed by the feed module 12. The recording device 10 also includes a first fixing module 16 that promotes the fixing of the recording agent to the recording medium by non-contact heating after recording, and a second fixing module 18 that promotes the fixing of the recording agent to the recording medium by contact heating. The recording device 10 also includes a cooling / reversing module 20 that cools the recording medium and performs a reversing operation when recording on both sides, and a loading module 22 to which the product is discharged and on which the discharged product is loaded. The recording device 10 also includes a control unit 200 (described later) that controls the overall operation of the recording device 10.

[0014] The recording module 14 includes a conveyor belt 24 that conveys the recording medium fed from the feeding module 12. The conveyor belt 24 conveys the recording medium while fixing it by air suction. The recording module 14 also includes a recording head 26 that is disposed at a position opposite to the conveyor belt 24 and discharges a recording agent onto the recording medium conveyed by the conveyor belt 24 to perform recording. A plurality of recording heads 26 are arranged in parallel along the conveying direction of the recording medium. In this embodiment, in addition to four colors of pigment inks, yellow (Y) ink, magenta (M) ink, cyan (C) ink, and black (K) ink, a processing liquid (P) that performs a predetermined process on the ink discharged onto the recording medium is used as the recording agent. Therefore, in this embodiment, in addition to the four colors of ink, Y ink, M ink, C ink, and K ink, the recording head 26 includes a plurality of line-type recording heads corresponding to the processing liquid. Note that the number of colors of the recording head 26 in the recording module 14 is not limited to the above four colors, and the number of recording heads is not limited to five. Furthermore, the ink is not limited to ink containing a pigment, and various known inks such as ink containing a dye can be used.

[0015] The recording head 26 is configured to be able to eject ink by, for example, an inkjet method. As the inkjet method, various known techniques can be used, such as a method using a heat element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS element, etc. In addition, in this embodiment, the recording device 10 is configured to eject ink by a method using a heat element. The recording head 26 is supplied with the corresponding type of ink from a main tank 402 (see FIG. 4) provided in the recording device 10 via a tube or the like.

[0016] The recording module 14 includes a maintenance unit 28 for maintaining and restoring the ink ejection performance of the recording head 26 in a good condition. The maintenance unit 28 includes, for example, a cap unit for protecting the nozzle surface of the recording head 26 on which nozzles for ejecting ink are formed, a wiping unit for wiping the nozzle surface, and a suction unit for sucking ink in the recording head 26 through the nozzles. The recording head 26 and the maintenance unit 28 are configured to be movable relative to each other, and for example, when the maintenance unit 28 is used, the maintenance unit 28 is located below the recording head 26 at a position facing the nozzle surface. Note that only the components of the maintenance unit 28 may be moved.

[0017] <Configuration of the control system of the recording device> Next, the configuration of the control system of the recording device 10 will be described. FIG. 2 is a block diagram showing the configuration of the control system of the recording device 10. The recording device 10 is communicably connected to a higher-level device (DFE) HC2, which is communicably connected to a host device HC1. In the host device HC1, manuscript data that is the source of a recorded image is generated or stored. Here, the manuscript data is generated in the form of an electronic file such as a document file or an image file. The manuscript data is transmitted from the host device HC1 to the higher-level device HC2. In the higher-level device HC2, the received manuscript data is converted into a data format that can be used by the recording device 10, for example, RGB data that expresses an image in RGB. The converted data is transmitted from the device HC2 to the recording device 10.

[0018] The control unit 200, which controls the overall operation of the recording device 10, includes a main controller 202 and an engine controller 204. The main controller 202 includes a processing unit 206, a storage unit 208, an operation unit 210, an image processing unit 212, communication interfaces (I / F) 214, 216, and a buffer 218.

[0019] The processing unit 206 is realized by a processor such as a CPU, executes programs stored in the storage unit 208, and performs overall control of the main controller 202. The storage unit 208 is realized by a storage device such as a ROM, a RAM, a hard disk, or an SSD, and stores programs and data executed by the processing unit 206, as well as providing a work area for the processing unit 206. The operation unit 210 is an input device such as a touch panel, a keyboard, or a mouse, and receives instructions from a user.

[0020] The buffer 218 is realized by, for example, a RAM, a hard disk, and an SSD, and is a storage area for storing various information. The image processing unit 212 is realized by, for example, an electronic circuit having an image processor, and is configured to be able to execute image processing on image data (RGB data) input from the higher-level device HC2. The communication I / F 214 communicates with the higher-level device HC, and the communication I / F 216 communicates with the engine controller 204. Note that, although the control unit 200 has been described as having one each of the processing unit 206, the storage unit 208, and the image processing unit 212, a plurality of these components may be provided. The configuration of the engine controller 204 will be described later.

[0021] The dashed arrows in Fig. 2 show an example of the flow of data input to the control unit 200. Image data (RGB data) received from the higher-level device HC2 via the communication I / F 214 is accumulated in the buffer 218. The image processing unit 212 reads the image data from the buffer 218, performs predetermined image processing on the read image data, generates recording data to be used by the engine controller 204, and stores the data in the buffer 218 again. The recording data stored in the buffer 218 is then transmitted from the communication I / F 216 to the engine controller 204. Thereafter, the engine controller 204 drives the recording head 26 based on the recording data, and a recording operation is performed to execute recording on the recording medium.

[0022] <Image processing> Next, the image processing executed by the image processing unit 212 will be described. Fig. 3 is a flowchart showing the detailed processing contents of the image processing executed by the image processing unit 212. The series of processing shown in the flowchart in Fig. 3 is performed by the CPU of the main controller 202 expanding program code stored in the ROM of the main controller 202 into the RAM of the main controller 202 and executing the program code. Alternatively, some or all of the functions of the steps in Fig. 3 may be executed by hardware such as an ASIC or an electric circuit. In this specification, the symbol S in the description of each process in the flowchart means that it is a step in that flowchart.

[0023] When image processing starts, first, in S302, the image processing unit 212 acquires RGB data (image data) stored in the buffer 218. In this embodiment, the RGB data is assumed to be composed of 8 bits for each RGB value. The RGB data is also assumed to have a data resolution of 600 dpi x 600 dpi. Next, in S304, the image processing unit 212 executes color conversion processing to convert the RGB data into CMYK data corresponding to ink colors that can be recorded by the recording device 10. This color conversion processing generates CMYK data composed of 12 bits for each CMYK value.

[0024] Thereafter, in S306, the image processing unit 212 performs a quantization process on the CMYK data to generate quantized data consisting of 3 bits for each of CMYK. For example, a dither method or an error diffusion method can be used as the quantization process. In this embodiment, quantized data having a data resolution of 600 dpi is generated by the quantization process. Then, in S308, the image processing unit 212 acquires attribute information. The attribute information is information indicating whether the attribute of the image recorded on the pixel is a character attribute or a thin line attribute, or another attribute (such as an image image attribute), and is composed of 1 bit. More specifically, when a character or a thin line is recorded on a certain pixel, "1" is acquired as the attribute information. On the other hand, when something other than a character or a thin line is recorded, "0" is acquired as the attribute information.

[0025] Note that S306 may be executed in parallel with the processes from S302 to S306. In addition, in this embodiment, the attribute information is acquired separately from the RGB data, but this is not limiting, and the image processing unit 212 may acquire the RGB data and the attribute information in a combined state.

[0026] After acquiring the quantized data and the attribute information, in S310, the image processing unit 212 combines the quantized data of 3 bits for each CMYK value with the 1-bit attribute information to generate combined data consisting of 4 bits for each CMYK value. The data resolution of the generated combined data is the same as that of the quantized data, 600 dpi x 600 dpi. In S312, the image processing unit 212 performs index expansion processing on the combined data to generate data consisting of 1-bit information for each CMYK value and the attribute information for two planes. In this index expansion, the quantized data of 3 bits for each CMYK value, which has a resolution of 600 dpi x 600 dpi, among the combined data, is expanded to 1-bit for each CMYK value at a resolution of 1200 dpi x 1200 dpi using an index pattern.

[0027] Thereafter, in S314, the image processing unit 212 performs a distribution process to distribute the expanded data to each recording head 26 that ejects different inks, and generates recording data to be used for recording. The generated recording data is 1-bit data with a resolution of 1200 dpi x 1200 dpi for each color of CMYK, and is data indicating whether or not to eject ink. Then, in S316, the image processing unit 212 transmits the generated recording data to the buffer 218, and ends this image processing.

[0028] <Circulation route> The recording device 10 is provided with a circulation path that supplies ink to the recording head 26, recovers the ink supplied to the recording head 26 outside the recording head 26, and is capable of circulating the ink to be supplied again to the recording head 26. Fig. 4 is a diagram showing an example of the circulation path of the recording device 10. Note that Fig. 4 shows a circulation path for one recording material. Therefore, in the recording device 10 that ejects four different inks and one treatment liquid, the circulation paths shown in Fig. 4 are provided one for each type of recording material, that is, five circulation paths are provided.

[0029] In the recording device 10, the recording head 26 and a buffer tank 404 capable of storing ink supplied from a main tank 402 are connected via flow paths 406, 408, and 410 to form a circulation path 400. In the circulation path 400, ink is circulated between the buffer tank 404 and the recording head 26 by driving three pumps 412, 414, and 416. Specifically, the flow path 406 is provided with a pump 412, and the ink stored in the buffer tank 404 is supplied to the recording head 26 by driving the pump 412. In addition, the flow path 408 is provided with a pump 414 (high pressure side), and the flow path 410 is provided with a pump 416 (low pressure side). By driving these pumps 414 and 416, ink is sucked from the recording head 26, and the sucked ink is transferred to the buffer tank 404.

[0030] The buffer tank 404 is provided with an air communication port (not shown) that communicates between the inside and the outside, and is configured to be able to discharge air bubbles generated in the stored ink to the outside. The buffer tank 404 is also connected to the main tank 402 via a flow path 418. A pump 420 is provided in the flow path 418. In the recording device 10, for example, when ink is consumed in the recording head 26 and the ink stored in the buffer tank 404 falls below a certain amount, the pump 420 is driven to supply the ink stored in the main tank 402 to the buffer tank 404. In the recording head 26, ink is consumed when ink is discharged (ejected) from the nozzles of the recording head 26, for example, when ink contributing to recording is discharged and ink not contributing to recording is discharged.

[0031] The pumps 414 and 416 are preferably positive displacement pumps having a quantitative liquid delivery capability. Specifically, the positive displacement pumps include tube pumps, gear pumps, diaphragm pumps, and syringe pumps. Alternatively, instead of using such pumps, a constant flow rate may be ensured by disposing a general constant flow rate valve or relief valve at the pump outlet. In addition, the flow path 408 in which the pump 414 is provided is connected to a common supply flow path 430 (described later) in the recording head 26, and the flow path 410 in which the pump 416 is provided is connected to a common recovery flow path 432 (described later) in the recording head 26.

[0032] When the recording head 26 is driven, a certain amount of ink is sucked from the common supply flow path 430 and the common recovery flow path 432 by the pump 414 and the pump 416. The flow rate at which ink is sucked is set to a level at which the temperature difference between the recording element substrates 428 (described later) in the recording head 26 does not affect the recording quality. If a flow rate is set too high, the negative pressure difference between the recording element substrates 428 becomes too large due to the influence of pressure loss in the flow paths in the discharge unit 422 (described later), resulting in uneven density of the image. For this reason, the flow rate is set taking into consideration the temperature difference and negative pressure difference between the recording element substrates 428.

[0033] The recording head 26 includes a discharge unit 422 that discharges ink, and a supply unit 424 that supplies ink to the discharge unit 422 and collects ink flowing out from the discharge unit 422 .

[0034] The supply unit 424 supplies the ink supplied via the flow path 406 to the discharge unit 422 via the negative pressure control unit 426. The negative pressure control unit 426 operates so that the pressure fluctuation downstream of the negative pressure control unit 426 (i.e., the discharge unit 422 side) falls within a certain range even when the flow rate in the circulation path fluctuates due to a change in the print duty during printing. The pressure fluctuation is kept within a certain range, for example, centered on a preset pressure.

[0035] The negative pressure control unit 426 includes two negative pressure adjustment mechanisms 426a and 426b. Any mechanism may be used for the negative pressure adjustment mechanisms 426a and 426b as long as the pressure downstream of the negative pressure adjustment mechanisms 426a and 426b can be controlled within a certain range of fluctuation centered on a desired set pressure. Of the negative pressure adjustment mechanisms 426a and 426b, the negative pressure adjustment mechanism 426a on the relatively high pressure setting side is connected to a common supply flow path 430 of the discharge unit 422 via a supply unit 424. The negative pressure adjustment mechanism 426b on the relatively low pressure setting side is connected to a common recovery flow path 432 of the discharge unit 422 via a supply unit 424.

[0036] As an example of the negative pressure adjustment mechanisms 426a and 426b, a configuration similar to a so-called pressure reducing regulator can be adopted. When a pressure reducing regulator is used, it is preferable to use a configuration in which the pump 412 pressurizes the upstream side of the negative pressure control unit 426 via the supply unit 424. With such a configuration, it is possible to suppress the influence of the head difference between the buffer tank 404 and the recording head 26, and it is possible to increase the degree of freedom in the layout of the buffer tank 404 of the recording device 10.

[0037] The pump 412 may be any pump having a head pressure equal to or higher than a certain pressure within the range of the ink circulation flow rate used when driving the recording head 26, and may be a turbo pump, a positive displacement pump, or the like. Specifically, a diaphragm pump or the like may be used as the pump 412. Also, instead of the pump 412, for example, a head tank disposed with a certain head difference with respect to the negative pressure control unit 426 may be used.

[0038] A plurality of recording element substrates 428 capable of ejecting ink are arranged in the ejection unit 422. In addition, in the ejection unit 422, a common supply flow path 430 to which ink supplied from the supply unit 424 is supplied, and a common recovery flow path 432 through which the supplied ink flows out to the supply unit 424 are provided extending along the arrangement direction of the recording element substrates 428. The common supply flow path 430 is connected to each recording element substrate 428 via an individual supply flow path 434. In addition, the common recovery flow path 432 is connected to each recording element substrate 428 via an individual recovery flow path 436.

[0039] As a result, the common supply flow path 430 and the common recovery flow path 432 communicate with each other via the individual supply flow paths 434, the recording element substrate 428, and the individual recovery flow paths 436. The common supply flow path 430 is connected to the negative pressure adjustment mechanism 426a and maintained at a relatively high pressure, while the common recovery flow path 432 is connected to the negative pressure adjustment mechanism 426b and maintained at a relatively low pressure, creating a pressure difference between the two paths. As a result, a portion of the ink supplied to the common supply flow path 430 flows into the common recovery flow path 432 via the individual supply flow paths 434, the recording element substrate 428, and the individual recovery flow paths 436.

[0040] With this configuration, in the ejection unit 422, ink flows in the common supply flow path 430 and the common recovery flow path 432, while a part of the ink passes through each recording element substrate 428. Therefore, heat generated in each recording element substrate 428 is discharged to the outside of the recording element substrate 428 by the ink flowing from the common supply flow path 430 to the common recovery flow path 432. In addition, during recording by the recording head 26, ink flows can be generated even in nozzles and pressure chambers that are not ejecting ink for recording. This makes it possible to suppress the viscosity of the ink in the nozzles and pressure chambers, and to discharge the viscosity-increased ink and foreign matter in the ink in the recording element substrate 428 to the outside of the recording element substrate 428, enabling high-speed, high-quality recording.

[0041] <Recording head> Next, the configuration of the recording head 26 will be described. FIG. 5 is a perspective view of the recording head 26, where (a) is a view from below on one side in the transport direction, and (b) is a view from above on the other side in the transport direction. FIG. 6 is an exploded configuration diagram of the recording head 26. In the following description, for ease of understanding, the recording head 26 capable of ejecting four types of ink will be described as an example. The configuration of the recording head 26 is not limited to this, and may be configured to eject only one type of ink, for example. The treatment liquid is ejected from a recording head that does not eject ink.

[0042] In the recording head 26, a plurality of recording element substrates 428 are arranged along the extension direction (Y direction) of the recording head 26 on the surface facing the recording medium transported in the transport direction by the transport belt 24 (see FIG. 5(a)). In the following explanation of the configuration of the recording head 26, the recording head 26 is provided with 15 recording element substrates 428, and each recording element substrate 428 is configured to be able to eject four types of ink: C ink, M ink, Y ink, and K ink.

[0043] The recording head 26 includes a signal input terminal 506 and a power supply terminal 508 electrically connected to each recording element substrate 428 via a flexible wiring board 502 and an electric wiring board 504 (see FIGS. 5(a) and 5(b)). The signal input terminal 506 and the power supply terminal 508 are electrically connected to an electric control unit (not shown) of the recording device 10. Each recording element substrate 428 is supplied with an ejection control signal from the electric control unit via the signal input terminal 506, and is supplied with power required for ejection from the electric control unit via the power supply terminal 508.

[0044] By consolidating the wiring using the electric circuit in the electric wiring board 504, the number of signal input terminals 506 and power supply terminals 508 is reduced compared to the number of recording element boards 428. This reduces the number of electrical connections that need to be removed when assembling the recording head 26 to the recording device 10 or when replacing the recording head 26.

[0045] The recording head 26 has connection parts 510 near both ends in the extension direction that are connected to flow paths in the circulation path. Ink is supplied to the recording head 26 from the flow paths in the circulation path provided for each type of ink via the corresponding connection parts 510. Ink also flows out of the recording head 26 to the flow paths in the circulation path provided for each type of ink via the corresponding connection parts 510.

[0046] The recording head 26 includes a housing 602 to which a supply unit 424 and an electric wiring board 504 are attached (see FIG. 6). A connection portion 510 is provided in the supply unit 424. A filter 440 (see FIG. 4) is provided inside the supply unit 424 to remove foreign matter from the ink being supplied. In this embodiment, two supply units 424 are provided in the recording head 26, each of which is provided with flow paths for two colors and a filter 440. A negative pressure control unit 426 is connected to the supply unit 424, and the ink supplied to the supply unit 424 is supplied to the corresponding negative pressure control unit 426.

[0047] The negative pressure control unit 426 is a unit equipped with negative pressure adjustment mechanisms 426a and 426b, and the pressure loss change in the circulation path caused by the fluctuation of the ink flow rate is significantly attenuated by the action of valves and spring members provided inside. For this reason, the two negative pressure adjustment mechanisms 426a and 426b are set to different control pressures, and the negative pressure adjustment mechanism 426a on the high pressure side is connected to the common supply flow path 430 of the ejection unit 422, and the negative pressure adjustment mechanism 426b on the low pressure side is connected to the common recovery flow path 432 of the ejection unit 422.

[0048] The housing 602 includes a discharge unit support portion 604 that supports the discharge unit 422 and an electric wiring board support portion 606 that supports the electric wiring board 504, and ensures the rigidity of the recording head 26. The electric wiring board support portion 606 is fixed to the discharge unit support portion 604 by screwing. The discharge unit support portion 604 corrects warping and deformation of the discharge unit 422 to ensure the relative position accuracy of the multiple recording element boards 428. This suppresses streaks and unevenness in the recorded image caused by the relative position accuracy. Therefore, the discharge unit support portion 604 preferably has sufficient rigidity, and is preferably made of, for example, a metal material such as SUS (Stainless Used Steel) or aluminum, or a ceramic such as alumina. In addition, the discharge unit support portion 604 is provided with openings 610 and 612 into which a joint rubber 608 is inserted. The ink supplied from the supply unit 424 is led to a third flow path member 626 (described later) of the discharge unit 422 through the joint rubber 608.

[0049] The ejection unit 422 includes an ejection module 614 including a recording element substrate 428, and a flow path member 616 that distributes ink from the supply unit 424 to the recording element substrate 428 and guides ink flowing out from the recording element substrate 428 to the supply unit 424. The ejection unit 422 also includes a cover member 618 that protects the periphery of the arranged recording element substrates 428.

[0050] The discharge module 614, details of which will be described later, includes a recording element substrate 428 and a flexible wiring substrate 502. The flow path member 616 is formed by laminating a first flow path member 622, a second flow path member 624, and a third flow path member 626. The flow path member 616 is fixed to the discharge unit support portion 604 by screws, which suppresses warping and deformation of the flow path member 616.

[0051] The cover member 618 is a member having a frame-shaped surface in which an opening 620 is provided, the opening being long in the extension direction of the recording head 26. The recording element substrate 428 and a sealant 710 (described later) in each ejection module 614 are exposed from the opening 620. The frame portion around the opening 620 serves as a contact surface for the cap member (not shown) of the maintenance unit 28. For this reason, an adhesive, sealant, filler, or the like is applied along the periphery of the opening 620 to fill in unevenness and gaps in the surface where the recording element substrate 428 in the ejection unit 422 is exposed, so that a closed space is formed between the cap member and the surface during capping.

[0052] <Discharge module> Next, a description will be given of the discharge module 614. Figure 7 is a schematic diagram of the discharge module 614, where (a) is a perspective view and (b) is an exploded view.

[0053] The ejection module 614 includes a recording element substrate 428, a flexible wiring substrate 502 that electrically connects the recording element substrate 428 and an electric wiring substrate 504, and a support member 702 that supports the recording element substrate 428 and one end side of the flexible wiring substrate 502. The support member 702 is provided with a communication port 704 that communicates with an opening 1004 (described later) provided in the recording element substrate 428.

[0054] The recording element substrate 428 is bonded to the support member 702 on a surface facing the nozzle forming surface 428a such that the opening 1004 of the recording element substrate 428 communicates with the communication port 704. The flexible wiring substrate 502 is electrically connected by wire bonding to terminals 1022 (described later) formed on the nozzle forming surface 428a of the recording element substrate 428, with one end side on which the terminals 706 are provided being supported by the support member 702. The wire bonding portion, i.e., the electrically connected portion, is sealed with a sealant 710.

[0055] A terminal 712 is provided on the other end side of the flexible wiring board 502, and the terminal 712 is electrically connected to a connection terminal 628 (see FIG. 6) of the electric wiring board 504. The support member 702 is a support body that supports the recording element substrate 428, and is also a flow path member that fluidly connects the recording element substrate 428 and the flow path member 616. For this reason, the support member 702 is preferably made of a material that has a high degree of flatness and can be joined to the recording element substrate 428 with sufficiently high reliability. Specifically, the support member 702 is made of, for example, alumina or a resin material.

[0056] <Flow path components> Next, the detailed configuration of the flow path member 616 will be described.

[0057] =First flow path member 622, second flow path member 624, and third flow path member 626= First, the configuration of the first flow path member 622, the second flow path member 624, and the third flow path member 626 in the flow path member 616 will be described. FIG. 8 is a configuration diagram of the first flow path member 622, the second flow path member 624, and the third flow path member 626. FIG. 8(a) is a diagram showing one surface 622a of the first flow path member 622, which is a surface on which the discharge module 614 is arranged, and FIG. 8(b) is a diagram showing the other surface 622b of the first flow path member 622, which is a surface that is joined to one surface 624a of the second flow path member 624. FIG. 8(c) is a diagram showing one surface 624a of the second flow path member 624, and FIG. 8(d) is a diagram showing the other surface 624b of the second flow path member 624, which is a surface that is joined to one surface 626a of the third flow path member 626. 8(e) is a diagram showing one surface 626a of the third flow path member 626, and FIG. 8(f) is a diagram showing the other surface 626b of the third flow path member 626, which is the surface that abuts against the discharge unit support part 604.

[0058] A plurality of (eight in FIG. 8) common flow channel grooves 802 are formed on the other surface 624b of the second flow channel member 624 along the extension direction of the second flow channel member 624 (see FIG. 8(d)). A common flow channel groove 804 is formed on one surface 626a of the third flow channel member 626 (see FIG. 8(e)). The common flow channel grooves 804 are provided at positions corresponding to the respective common flow channel grooves 802 provided on the other surface 624b when one surface 626a of the third flow channel member 626 is joined to the other surface 624b of the second flow channel member 624, and in a number corresponding to the respective common flow channel grooves 802. As a result, when the second flow channel member 624 and the third flow channel member 626 are joined, eight common flow channels are formed by the common flow channel grooves 802 and the common flow channel grooves 804. These common channels become the common supply flow channel 430 and the common recovery flow channel 432 formed for each ink (see FIG. 9).

[0059] The third flow path member 626 is provided with communication openings 806 penetrating from one surface 626a to the other surface 626b (see FIGS. 8(e) and 8(f)). The communication openings 806 are provided on both end sides in the extending direction of the third flow path member 626, and on the one surface 626a, they are located at both ends of each common flow path groove 804. Furthermore, when the third flow path member 626 is fixed to the discharge unit support part 604, the communication openings 806 communicate with a flow path (not shown) provided in the joint rubber 608, thereby fluidly connecting the third flow path member 626 and the supply unit 424.

[0060] The second flow path member 624 is provided with communication openings 808 penetrating from one surface 624a to the other surface 624b (see FIGS. 8(c) and 8(d)). A plurality of communication openings 808 are provided in each common flow path groove 802, and are formed at positions that communicate with individual flow path grooves 810 (described later) provided in the first flow path member 622 when the second flow path member 624 and the first flow path member 622 are joined together.

[0061] The first flow path member 622 is provided with an individual flow path groove 810 formed on the other surface 622b at an incline with respect to the short-side direction of the first flow path member 622 (a direction perpendicular to the extending direction of the first flow path member 622) (see FIG. 8(b)). The first flow path member 622 is provided with a communication port 812 penetrating from one surface 622a to the other surface 622b (see FIGS. 8(a)(b)). The communication port 812 is located in an area located in the center of the short-side direction of the first flow path member 622. The communication port 812 is provided at a position where it is fluidically connected to the recording element substrate 428 via the communication port 704 of the support member 702 when the ejection module 614 is disposed on one surface 622a of the first flow path member 622. The communication port 812 is located at one end of the individual flow path groove 810. The individual flow passage groove 810 communicates with the communication port 808 at the other end.

[0062] The first flow path member 622, the second flow path member 624, and the third flow path member 626 are preferably made of a material that is resistant to corrosion by ink and has a low linear expansion coefficient. Specific examples of the material that can be used include composite materials (resin materials) made of alumina, LCP (liquid crystal polymer), PPS (polyphenyl sulfide), and PSF (polysulfone) as a base material to which inorganic fillers such as silica particles and fibers are added. The flow path member 616 is formed by laminating the first flow path member 622, the second flow path member 624, and the third flow path member 626 and bonding them together. When the first flow path member 622, the second flow path member 624, and the third flow path member 626 are made of a resin composite resin material, they may be joined by welding.

[0063] =Flow path in flow path member= Next, the flow paths formed in the flow path member 616 will be described. Fig. 9 shows the flow paths formed in the flow path member 616, where (a) is a partially enlarged view and (b) is a cross-sectional view taken along line IXb-IXb in (a). Fig. 9(a) is a view seen from one surface 622a of the first flow path member 622, with the flow paths formed therein indicated by dashed lines and the recording element substrate 428 disposed above indicated by a two-dot chain line.

[0064] The flow path member 616 is provided with a common supply flow path 430 and a common recovery flow path 432 extending in the longitudinal direction of the recording head 26 so as to correspond to each ink (see FIG. 9(a)). In FIG. 9(a), the common supply flow path 430a and the common recovery flow path 432a correspond to the same ink, and the common supply flow path 430b and the common recovery flow path 432b correspond to the same ink. In addition, the common supply flow path 430c and the common recovery flow path 432c correspond to the same ink, and the common supply flow path 430d and the common recovery flow path 432d correspond to the same ink.

[0065] A plurality of individual supply flow paths 434 formed by individual flow path grooves 810 are connected to the common supply flow path 430 via communication ports 808. Specifically, an individual supply flow path 434a is connected to the common supply flow path 430a via the communication port 808, and an individual supply flow path 434b is connected to the common supply flow path 430b via the communication port 808. Furthermore, an individual supply flow path 434c is connected to the common supply flow path 430c via the communication port 808, and an individual supply flow path 434d is connected to the common supply flow path 430d via the communication port 808.

[0066] Furthermore, a plurality of individual recovery flow paths 436 formed by individual flow path grooves 810 are connected to the common recovery flow path 432 via communication ports 808. Specifically, the individual recovery flow path 436a is connected to the common recovery flow path 432a via the communication port 808, and the individual recovery flow path 436b is connected to the common recovery flow path 432b via the communication port 808. Furthermore, the individual recovery flow path 436c is connected to the common recovery flow path 432c via the communication port 808, and the individual recovery flow path 436d is connected to the common recovery flow path 432d via the communication port 808.

[0067] With this configuration, the common supply flow path 430 is fluidly connectable to the recording element substrate 428 arranged in the center of the flow path member 616 via the individual supply flow paths 434, and the common recovery flow path 432 is fluidly connectable to the recording element substrate 428 arranged in the center of the flow path member 616 via the individual recovery flow paths 436.

[0068] When the discharge module 614 is placed on the flow path member 616, the individual recovery flow path 436 communicates with the discharge module 614 via the communication port 812 (see FIG. 9(b)). Although not shown in cross section, when the discharge module 614 is placed on the flow path member 616, the individual supply flow path 434 also communicates with the discharge module 614 via the communication port 812.

[0069] As a result, the flow path member 616 is fluidly connected to a pressure chamber 1120 (described later) provided in the recording element substrate 428 via the support member 702. Note that, in the pressure chamber 1120, a recording element 1118 and a nozzle 1002 are arranged, as described later.

[0070] Here, the common supply flow path 430 is connected to the negative pressure control unit 426 (negative pressure adjustment mechanism 426a) via the supply unit 424, and the common recovery flow path 432 is connected to the negative pressure control unit 426 (negative pressure adjustment mechanism 426b) via the supply unit 424. Therefore, a pressure difference is generated between the common supply flow path 430 and the common recovery flow path 432 by the negative pressure control unit 426. As a result, in the recording head 26, a part of the ink supplied for each ink flows in the order of the common supply flow path 430, the individual supply flow path 434, the recording element substrate 428, the individual recovery flow path 436, and the common recovery flow path 432.

[0071] <Flow path configuration in the recording element substrate> Next, the flow path configuration in the recording element substrate 428 will be described. Fig. 10 is an external view of the recording element substrate 428, where (a) is a view seen from the nozzle forming surface on which nozzles are formed, and (b) is a view seen from the abutment surface that abuts against the support member 702. Fig. 11 is a view showing the flow path configuration of the recording element substrate 428, where (a) is an enlarged view of the inside of frame XIa in Fig. 10(a), and (b) is a cross-sectional view along line XIb-XIb in Fig. 10(a).

[0072] The recording element substrate 428 has four nozzle rows corresponding to the respective inks formed on one surface (see FIG. 10(a)). In each nozzle row, a plurality of nozzles 1002 are arranged along the extension direction of the recording element substrate 428. In addition, the recording element substrate 428 has an opening 1004 fluidly connected to the communication port 704 of the support member 702 on the other surface opposite to the one surface (see FIG. 10(b)).

[0073] The recording element substrate 428 includes a substrate 1106 on which are formed a supply path 1102 for supplying ink to pressure chambers 1120 (described later) and a recovery path 1104 for recovering ink from the pressure chambers 1120 (see FIG. 11(b)). On one surface of the substrate 1106, a nozzle forming member 1110 is provided on which a nozzle row having a plurality of nozzles 1002 for ejecting ink is formed. The substrate 1106 is formed of, for example, silicon (Si), and the nozzle forming member 1110 is formed of, for example, a photosensitive resin. Also, on the other surface of the substrate 1106 opposite to the one surface, a cover plate 1112 is formed.

[0074] The supply path 1102 and the recovery path 1104 extend along the extension direction of the nozzle row in the nozzle forming member 1110 (see FIG. 11(a)). The supply path 1102 is disposed on one side of each nozzle row in the short side direction of the recording element substrate 428, and the recovery path 1104 is disposed on the other side of each nozzle row in the short side direction. Furthermore, on one surface of the substrate 1106, a plurality of supply ports 1114 communicating with the supply path 1102 are arranged along the extension direction of the nozzle row. Furthermore, on one surface of the substrate 1106, a plurality of recovery ports 1116 communicating with the recovery path 1104 are arranged along the extension direction of the nozzle row.

[0075] On one side of the substrate 1106, a recording element 1118, which is a heat generating element (electrothermal conversion element) for causing the ink to bubble by thermal energy, is provided at a position facing the nozzle 1002. That is, in this embodiment, the recording element 1118 functions as an energy generating element that generates energy for ejecting ink from the nozzle. This recording element 1118 is located in a pressure chamber 1120 formed in the nozzle forming member 1110. This pressure chamber 1120 is formed for each recording element 1118 by a partition wall 1108. In addition, on one side of the substrate 1106, a terminal 1122 is provided that is electrically connected to the recording element 1118 by an electric wiring (not shown) provided on the substrate 1106. Therefore, the recording element 1118 generates heat based on an ejection control signal input via the electric wiring substrate 504 and the flexible wiring substrate 502, and boils the ink in the pressure chamber 1120. The force of bubbles generated by this boiling causes the ink in the pressure chamber 1120 to be ejected from the nozzle 1002 .

[0076] The cover plate 1112 is provided with an opening 1004 communicating with the supply path 1102 and the recovery path 1104. Ink is supplied to the supply path 1102 from the opening 1004 communicating therewith, and ink flows out to the opening 1004 communicating therewith. In this embodiment, three openings 1004 are formed in each supply path 1102, and two openings 1004 are formed in each recovery path 1104. The cover plate 1112 also functions as a lid forming a part of the supply path 1102 and the recovery path 1104 formed in the substrate 1106. The cover plate 1112 is required to have sufficient corrosion resistance against ink, and from the viewpoint of preventing color mixing, the opening shape and the opening position of the opening 1004 are required to have high accuracy. For this reason, it is preferable to use a photosensitive resin material or a silicon plate as the material of the cover plate 1112, and to provide the opening 1004 by a photolithography process. In this way, the cover plate 1112 converts the pitch of the flow paths by the openings 1004, and considering the pressure loss, it is preferable that the cover plate 1112 is thin, and is made of, for example, a film-like material.

[0077] In the recording element substrate 428, the supply path 1102 is connected to the common supply flow path 430, and the recovery path 1104 is connected to the common recovery flow path 432, so that a pressure difference occurs between the supply path 1102 and the recovery path 1104. During the ink circulation in the circulation path, this pressure difference causes ink to flow from the supply path 1102 to the recovery path 1104 via the supply port 1114, the pressure chamber 1120, and the recovery port 1116. This flow allows, for example, thickened ink, bubbles, foreign matter, etc., generated by evaporation from the nozzle 1002 in the nozzle 1002 or the pressure chamber 1120 that is not recording to flow out to the recovery path 1104. In addition, the increase in the viscosity of the ink in the nozzle 1002 or the pressure chamber 1120 can be suppressed. The ink that flows out to the recovery path 1104 is collected in the flow path member 616 via the opening 1004 of the cover plate 1112 and the communication port 704 of the support member 702.

[0078] The ink supplied to the recording head 26 flows into the communication port 812 through the joint rubber 608, the communication port 806 in the third flow path member 626, the common supply flow path 430, the communication port 808 in the second flow path member 624, and the individual supply flow path 434 in the first flow path member 622. Thereafter, the ink flows into the pressure chamber 1120 through the communication port 704 in the support member 702, the opening 1004 in the cover plate 1112, the supply path 1102 and the supply port 1114 provided in the substrate 1106.

[0079] Of the ink supplied to the pressure chamber 1120, the ink that is not ejected from the nozzle 1002 flows out to the recovery port 1116 in the substrate 1106, the recovery path 1104, the opening 1004 in the cover plate 1112, and the communication port 704 in the support member 702. After that, the ink flows out through the communication port 812 in the first flow path member 622, the individual recovery flow path 436, the communication port 808 in the second flow path member 624, the common recovery flow path 432, and the communication port 806 in the third flow path member 626, and flows out to the joint rubber 608. Then, the ink flows out from the connection portion 510 provided in the supply unit 424 to the outside of the recording head 26.

[0080] In the circulation path of this embodiment, not all of the ink that flows into the common supply flow path 430 of the ejection unit 422 is supplied to the pressure chamber 1120 via the individual supply flow path 434. Some ink flows out from the common supply flow path 430 to the supply unit 424 without flowing into the individual supply flow path 434. In this way, by providing a flow path that does not pass through the recording element substrate 428, it is possible to suppress the backflow of the circulating flow of the ink even if a recording element substrate 428 having a fine flow path with a large flow resistance is used. Therefore, in the recording head 26 according to this embodiment, it is possible to suppress the thickening of the ink near the pressure chamber 1120 and the nozzle 1002, and therefore it is possible to suppress deviation of the ejection direction from the normal direction and ejection failure, and it becomes possible to perform high-quality recording.

[0081] <Positional relationship between recording element substrates> Next, a description will be given of the positional relationship between adjacent recording element substrates 428 among the multiple recording element substrates 428 arranged in the extending direction of the recording head 26. Fig. 12 is a diagram showing the positional relationship between adjacent recording element substrates 428.

[0082] The recording element substrate 428 is formed in a substantially parallelogram shape (see FIG. 10(a)), and each of the nozzle rows 1202, 1204, 1206, and 1208 is arranged so as to be inclined at a predetermined angle with respect to the transport direction of the recording medium. In the corresponding nozzle rows of the adjacent recording element substrates 428, one nozzle 1002 is arranged so as to overlap in the transport direction of the recording medium (see dashed line D in FIG. 12). The number of nozzles overlapping in the transport direction is not limited to one, and may be multiple.

[0083] By arranging the adjacent recording element substrates 428 in this manner, even if the position of the recording element substrate 428 is slightly shifted from the predetermined position, black streaks and white spots occurring in the recorded image can be made difficult to see by driving control of the overlapping nozzles. The recording element substrates 428 can also be arranged in a straight line (inline) instead of in a staggered arrangement as shown in FIG. 12. Note that, in this embodiment, the recording element substrate 428 is formed into a substantially parallelogram shape, but is not limited to this, and may be, for example, a quadrilateral shape having long and short sides such as a rectangle or a trapezoid, or various other known shapes.

[0084] <Configuration of the vicinity of the heat application portion on the recording element substrate> Next, a description will be given of the configuration in the vicinity of the recording elements 1118 which are the thermal action parts in the recording element substrate 428. Fig. 13 is a diagram showing the configuration in the vicinity of the recording elements 1118 in the recording element substrate 428. Fig. 13(a) is a diagram showing the configuration inside the pressure chamber 1120. Fig. 13(b) is a cross-sectional view taken along line XIIIb-XIIIb in Fig. 13(a).

[0085] In the recording element substrate 428, the substrate 1106 on which the nozzle forming member 1110 is laminated is formed by laminating wiring, recording elements 1118, and other components on a base (not shown). In this embodiment, an insulating heat storage layer 1304 formed of a thermal oxide film, a SiO film, a SiN film, or the like is formed on the base. The recording elements 1118 are arranged on the heat storage layer 1304. An electrode wiring layer (not shown) serving as wiring formed of a metal material such as Al, Al-Si, or Al-Cu is connected to the recording elements 1118 via a tungsten plug 1302. An insulating protective layer is formed on the recording elements 1118 by the heat storage layer 1304.

[0086] Such an insulating protective layer (the uppermost layer of the heat storage layer 1304) is provided with a protective layer 1306 for blocking contact with the ink in the pressure chamber 1120. This protective layer 1306 includes a lower protective layer 1308, an upper protective layer 1310, and an adhesive protective layer 1312, and protects the surface of the recording element 1118 from chemical and physical shocks caused by heat generation of the recording element 1118. For example, the lower protective layer 1308 is made of tantalum (Ta), the upper protective layer 1310 is made of iridium (Ir), and the adhesive protective layer 1312 is made of tantalum (Ta). For this reason, the protective layer 1306 has electrical conductivity.

[0087] A protective layer 1314 is provided on the adhesive protective layer 1312 to improve ink resistance and adhesion to the nozzle forming member 1110. The protective layer 1314 is preferably formed of a film that is difficult to dissolve in ink, such as SiCN / SiOC. In the protective layer 1306, the adhesive protective layer 1312 and the protective layer 1314 are not formed in most parts of the recording elements 1118, and the upper protective layer 1310 is exposed inside the pressure chambers 1120.

[0088] The upper protective layer 1310 is formed of a material that contains a metal that dissolves into the ink in the pressure chamber 1120 by electrochemical reaction, and does not form an oxide film that prevents the dissolution by heating. When ink is ejected from the nozzle 1002, the ink in the pressure chamber 1120 contacts the surface of the upper protective layer 1310, and cavitation occurs in which the temperature rises instantaneously on the surface by driving the recording element 1118, causing the ink to foam and then disappear. For this reason, in this embodiment, the upper protective layer 1310 is formed of iridium, which is highly corrosion-resistant and highly reliable, so as to contact the ink on the recording element 1118.

[0089] <How to deal with burnt food> The recording element substrate 428 is configured to be capable of suppressing and removing kogation that accumulates on the upper protective layer 1310 by driving the recording elements 1118. Kogation occurs when coloring materials and additives contained in ink are decomposed at the molecular level by high temperature heating and converted into poorly soluble substances, which are then physically adsorbed onto the surface of the upper protective layer 1310. When kogation accumulates on the upper protective layer 1310, the efficiency of converting thermal energy into ejection energy decreases, causing a shortage of ejection power, i.e., a decrease in the ejection speed.

[0090] = Suppression of burning = In the recording element substrate 428, in order to suppress kogation, the portion directly above the recording element 1118 of the upper protective layer 1310 is made into an electrode 1316, and an opposing electrode 1318 corresponding to the electrode 1316 is provided in the vicinity of the recovery port 1116 (see FIG. 13) to form an electric field in the pressure chamber 1120. Note that the electrode 1316 functions as a negative electrode during a recording operation. This makes it possible to move particles such as pigments in the ink that are negatively charged away from the surface of the electrode 1316, that is, the surface of the upper protective layer 1310 above the recording element 1118.

[0091] In this way, by reducing the presence rate of negatively charged particles (hereinafter also referred to as "negatively charged particles") near the surface of the upper protective layer 1310, it is possible to suppress the accumulation of kogation during a recording operation on the surface of the upper protective layer 1310 on the recording element 1118. That is, in the recording element substrate 428, when the upper protective layer 1310 is heated to a high temperature, the occurrence of kogation is suppressed by reducing the presence rate of coloring materials, additives, etc. that cause kogation near the surface of the upper protective layer 1310.

[0092] Here, the mechanism of electric field control (potential control) during kogation suppression in this embodiment will be described with reference to Fig. 14. Fig. 14 is a diagram showing the electric field and negatively charged particles in a potential controlled state and a potential uncontrolled state. In a state where the potential between the electrode 1316 and the counter electrode 1318 is not controlled, negatively charged particles 1402 in the ink are dispersed approximately uniformly in the ink in the pressure chamber 1120, as shown in Fig. 14(a).

[0093] When a voltage is applied so that the potential of the electrode 1316 is relatively lower than the potential of the counter electrode 1318, the result is as shown in FIG. 14(b). At this time, the potential difference between the electrode 1316 and the counter electrode 1318 is about 0.5 to 2.5 V. Regarding this potential difference, when the upper protective layer 1310 is formed of iridium, if the potential difference between the two electrodes exceeds 2.5 V, the surface of the electrode 1316 will dissolve into the ink, so the potential difference is set to a level at which the electrode 1316 does not dissolve into the ink. That is, in this embodiment, assuming that the potential difference between the electrode 1316 and the counter electrode 1318 during the recording operation is ΔVp and the potential difference between the electrode 1316 and the counter electrode 1318 during aging is ΔVa, it is preferable that the absolute values ​​of ΔVp and ΔVa are 2.5 V or less.

[0094] In FIG. 14B, an electric field 1404 is formed between the electrode 1316 and the counter electrode 1318 via the ink, but no current flows. The electrode 1316 has a negative potential relative to the counter electrode 1318, so that the negative potential particles 1402 are repelled from the surface of the electrode 1316, and the presence rate of the negative potential particles 1402 in the vicinity of the surface of the electrode 1316 decreases. The negative potential particles 1402 receive a repulsive force 1406 from the surface of the electrode 1316 along the electric field lines of the electric field 1404 formed in the ink (see FIG. 14D). Due to this mechanism, the larger the potential difference ΔV (=Vc-Vh) when the potential of the counter electrode 1318 is Vc and the potential of the electrode 1316 is Vh, the more the negative potential particles 1402 that cause kogation are repelled from the electrode 1316, and kogation on the electrode 1316 becomes less likely to occur.

[0095] =Removing burnt food= Kogane adhering to the electrode 1316, that is, kogane adhering near the surface of the upper protective layer 1310, is removed by applying a voltage between the electrode 1316 and the counter electrode 1318 to dissolve the surface portion of the upper protective layer 1310 into the ink and lifting off the kogane. At this time, a voltage of 3 V or more is applied between the electrode 1316 and the counter electrode 1318, at which the electrode material iridium is dissolved. At this time, it is preferable to apply the voltage to the electrode 1316 while reversing the direction of the voltage. By removing the kogane in this way, the surface of the electrode 1316 is left almost free of kogane.

[0096] =Aging (burnt deposits)= Furthermore, the recording element substrate 428 is configured to perform aging to change the upper protective layer 1310 from a state in which no kogation is present (or which has almost no kogation present) to a state in which there is an appropriate amount of kogation by driving the recording elements 1118. The timing for performing aging is when starting to use a brand new recording apparatus 10 that has no ejection history, or after removing kogation from the upper protective layer 1310.

[0097] Fig. 15 is a graph showing the relationship between the number of ejections and the ejection speed when aging and kogation removal are performed. In Fig. 15, the horizontal axis shows the number of ejections, and the vertical axis shows the ejection speed. Also in Fig. 15, Agn (n is a positive integer including 0) shows the aging implementation section, and KTn (n is a natural number) shows the timing when kogation removal is performed. Furthermore, in Fig. 15, P shows the number of ejections in aging, Phn shows the normal printing section from the timing when aging ends to the timing when kogation removal is required, and P2n-P (P2n-1) shows the number of ejections at Phn. Note that n is a natural number.

[0098] As shown in Fig. 15, the removal of kogation causes the discharge speed to rise to near V0, and by performing aging, the excessively increased discharge speed can be reduced to V1, and the subsequent change in the discharge speed can be made gentler (also referred to as "stabilization" in the following explanation). The behavior of the discharge speed is related to the amount of kogation adhering to the surface of the upper protective layer 1310. In other words, the vertical axis in Fig. 15 corresponds to the amount of kogation adhering, and a lower discharge speed means a greater amount of kogation adhering.

[0099] =Conditions for each phase= In the aging, Vp≧0 and ΔVa<ΔVp. ΔVp is a value obtained by subtracting the potential Vph of the electrode 1316 during the recording operation from the potential Vpc of the counter electrode 1318 during the recording operation. Also, ΔVa is a value obtained by subtracting the potential Vah of the electrode 1316 during the aging operation from the potential Vac of the counter electrode 1318 during the aging operation. By using ΔVa (smaller than ΔVp) as the potential difference during aging, it becomes easier for kogation to adhere to the upper protective layer 1310 than when ΔVp is used (see FIG. 14(c)).

[0100] Furthermore, in aging, in order to further accelerate the change in the ejection characteristics, that is, to promote the adhesion of kogation, a pulse with a voltage value larger than that of a normal voltage pulse during printing operation, etc., may be applied to the extent that does not damage the printing element 1118. Furthermore, in aging, the application time of the pulse may be made longer than in normal times. Thus, in this embodiment, during aging, the printing element 1118 is driven under conditions (driving conditions during aging drive described later) that make it easier for kogation to adhere to the surface of the upper protective layer 1310 than under the conditions during normal printing operation. Also, during aging, the printing element 1118 is driven under conditions (driving conditions during aging drive described later) that make it easier for kogation to adhere to the surface of the upper protective layer 1310 than under the conditions during normal printing operation. 5 The ejection speed becomes stable by ejecting about 150g of ink (the number of ejections during aging, which will be described later). In this case, the weight of the ejected ink is about 150g.

[0101] On the other hand, after aging, for example, 5×10 8By ejecting ink of about 1000 times the number of ejections, the ejection speed drops to V2, and it is time to remove the kogation. The time to remove the kogation is, for example, the time when the ejection characteristics deteriorate to the extent that the quality of the finished product deteriorates due to the kogation adhering to the upper protective layer 1310. Therefore, in this embodiment, after aging, the number of ejections P2n-P(2n-1) in the normal printing section Phn is 5×10 8 When the timing is set to 0, the timing is set to remove the burnt ink. The specific timing and number of shots in the burnt ink process are managed, for example, by using a counter that counts the number of ejected shots. In this embodiment, the number of ejected shots is calculated by a dot number calculation unit 1716 (see FIG. 17), which will be described later. Specifically, for example, the entire recording head width is divided into a plurality of regions, and the number of ejected shots (number of ejected dots) in a window that covers the entire nozzle array is counted, and the number of ejected shots in the window is determined by dividing the number of ejected shots by the number of nozzles in the window. In other words, in this embodiment, the number of ejected shots calculated by the dot number calculation unit 1716 is calculated as the number of ejected shots per nozzle in each recording element substrate 428. Note that the method for calculating the number of ejected shots can be performed using various known techniques, and therefore a detailed description thereof will be omitted.

[0102] <Adjusting the ink concentration in the circulation path> =Recording process= First, the processes executed during printing in the printing apparatus 10 will be described. Fig. 16 is a timing chart of a number of processes executed during printing in the printing apparatus 10. In the following description, the state of the printing apparatus 10 before executing a printing operation based on a job will be appropriately referred to as a standby state. When the printing apparatus 10 is in a standby state, the pumps 412, 414, and 416 are stopped, and ink is not circulating in the circulation path 400. Also, the temperature of the print head 26 in the standby state is T0°C, and the humidity at the nozzle 1002 is RH1.

[0103] When a printing operation based on a job is started in the printing apparatus 10, the engine controller 204 drives the pumps 412, 414, and 416 to circulate the ink in the circulation path 400. Next, the cap portion (not shown) in the maintenance unit 28 is separated from the nozzle surface on which the nozzles of the print head 26 are formed, and the nozzles 1002 are exposed to the outside. As a result, the humidity around the nozzles 1002 becomes equal to the humidity (RH0) of the installation environment of the printing apparatus 10, and the ink evaporates from the nozzles 1002. Thereafter, the temperature control heater (not shown) provided on the printing element substrate 428 is driven to raise the temperature of the printing element substrate 428 to a temperature required for the printing operation. Then, when the flow rate (circulation flow rate) of the ink in the circulation path 400 reaches a predetermined speed V and the temperature of the printing element substrate 428 reaches a predetermined temperature Top° C., the printing operation is performed to print on the printing medium.

[0104] The evaporation rate of ink from the nozzles 1002 increases sharply when the cap portion is separated. Furthermore, during a printing operation, the ink mainly evaporates from non-ejecting nozzles that do not eject ink. The evaporation of ink from non-ejecting nozzles increases the ink concentration in the circulation path 400. Since the circulation flow rate cannot be controlled individually for each nozzle 1002, the evaporation rate of ink from each non-ejecting nozzle during a printing operation is constant. Note that the evaporation of ink from nozzles during a printing operation is dominated by the evaporation component from non-ejecting nozzles, but in this embodiment, when calculating the amount of ink evaporation, in order to simplify the calculation, it is assumed that evaporation proceeds uniformly for all nozzles regardless of the ejection state.

[0105] After the printing operation is completed, the pumps 412, 414, and 416 are stopped to stop the circulation of ink in the circulation path 400. After a predetermined time has elapsed since the pumps 412, 414, and 416 were stopped, the circulating flow in the nozzle 1002 completely stops. Therefore, when the pumps 412, 414, and 416 are stopped, the evaporation rate from the non-ejecting nozzles drops sharply. Then, the cap portion is brought into contact with the nozzle face of the print head 26. As a result, the humidity around the nozzle 1002 rises and recovers to the humidity RH1 before the printing operation of the job was performed, and the evaporation rate from the non-ejecting nozzles converges to 0.

[0106] =Adjustment method= In this way, in the recording device 10, evaporation of the liquid components in the ink is promoted during the recording operation, and the ink concentration in the circulation path 400 increases. For this reason, in the recording device 10, the ink concentration (e.g., pigment concentration) in the circulation path that has increased due to the recording operation or the like is adjusted to a concentration that does not cause a decrease in the recorded image quality.

[0107] When adjusting the ink concentration in the circulation path, first, an acquisition process is executed to acquire an estimated value of the ink concentration in the circulation path 400 that has thickened due to a printing operation or the like. Then, based on the acquired estimated value of the ink concentration, a part of the thickened ink is discharged from the circulation path 400 and new ink is supplied from the main tank 402 to adjust the ink concentration in the circulation path 400. Hereinafter, the process of adjusting the ink concentration in the circulation path 400 is appropriately referred to as "concentration adjustment". By this concentration adjustment, the ink concentration in the circulation path 400 is adjusted to within a predetermined concentration range in which deterioration of the recording image quality is unlikely to occur. In this embodiment, the discharge of ink from the circulation path 400 during the concentration adjustment is realized by driving the printing element 1118 to eject ink from the nozzle 1002.

[0108] Functional configuration of engine controller 204 The acquisition process and the concentration adjustment are executed by the engine controller 204. Fig. 17 is a block diagram showing the functional configuration of the engine controller 204. Each component of the engine controller 204 shown in Fig. 17 is realized by a known hardware configuration such as a CPU, a ROM, and a RAM provided in the engine controller 204.

[0109] The engine controller 204 includes a printhead temperature adjustment control unit 1702 that controls temperature adjustment of the printhead 26 by a temperature adjustment heater (not shown) provided on the printhead substrate 428 based on the detection result of a temperature detection unit 1701 provided on the printhead substrate 428. The engine controller 204 also includes an evaporation amount acquisition unit 1704 that acquires the amount of evaporation per unit time from the nozzle 1002. The engine controller 204 also includes a dew point temperature calculation unit 1706 that calculates the dew point temperature around the nozzle surface of the printhead 26 based on the detection result of a temperature and humidity sensor 1700 provided in the printing apparatus 10. The temperature and humidity sensor 1700 is configured to be able to detect the temperature and humidity (relative humidity) of the space between the printhead 26 and the printing medium.

[0110] The engine controller 204 includes an ink discharge control unit 1708 that controls the discharge of ink from the circulation path 400 and the supply of ink to the circulation path 400 associated with the discharge. The engine controller 204 also includes a density estimate calculation unit 1710 that calculates an estimate of the density of the ink in the circulation path 400, and an image density correction unit 1712 that performs image density correction. The engine controller 204 also includes a print duty calculation unit 1714 that calculates a print duty based on a calculation result in a dot number calculation unit 1716, which will be described later. The engine controller 204 also includes a dot number calculation unit 1716 that calculates the number of ink droplets ejected from the nozzles of the print head 26 based on print data.

[0111] = Acquisition process = Next, an acquisition process for acquiring an estimated value of the concentration of ink in the circulation path 400 will be described. Fig. 18 is a flowchart showing detailed processing of the acquisition process. A series of processes shown in the flowchart of Fig. 18 is performed by the CPU of the engine controller 204 expanding program code stored in the ROM of the engine controller 204 into the RAM of the engine controller 204 and executing it. Alternatively, some or all of the functions of the steps in Fig. 18 may be performed by hardware such as an ASIC or an electric circuit.

[0112] When the acquisition process is started, first, in S1802, the printhead temperature adjustment controller 1702 acquires the temperature of each printing element substrate 428. Specifically, the detection results of the temperature detectors 1701 provided on each printing element substrate 428 are acquired. Then, in S1804, the printhead temperature adjustment controller 1702 acquires a target temperature for temperature adjustment control of the printing element substrate 428 in the printhead 26. In this embodiment, the highest temperature among the temperatures acquired by the temperature detectors 1701 in S1702 is acquired as the target temperature. Note that the target temperature may be the average value of the detection results of the temperature detectors 1701, or the lowest temperature.

[0113] Next, in S1806, the dew point temperature calculation unit 1706 acquires the temperature and relative humidity detected by the temperature and humidity sensor 1700, and calculates the dew point temperature using the acquired temperature and relative humidity. Then, in S1808, the evaporation amount acquisition unit 1704 acquires the amount of ink evaporation per unit time from the nozzle based on the dew point temperature acquired in S1806 and the target temperature acquired in S1804. A table showing the amount of ink evaporation per unit time corresponding to the combination of the temperature and dew point temperature of the recording element substrate 428 is stored in a storage area such as a ROM or RAM of the engine controller 204. Therefore, in S1808, the evaporation amount of ink per unit time is acquired using the table.

[0114] In addition, in S1810, the dot number calculation unit 1716 counts the number of ink droplets ejected from all the nozzles 1002 of the print head 26. In S1812, the print duty calculation unit 1714 calculates the print duty per predetermined time and acquires the amount of ink consumed in the print operation. Here, in this embodiment, the density estimate value acquired by this acquisition process is used to execute a determination process for determining the mode of the maintenance process including the control of kogation and the density adjustment, as will be described in detail later. This determination process is executed at predetermined intervals. Therefore, in S1810, if a print operation is executed between the most recent determination process and the current determination process, the number of ink droplets ejected from the print head 26 between the most recent acquisition process and the current acquisition process is calculated based on the print data. In addition, in S1812, the amount of ink consumed between the most recent acquisition process and the current acquisition process is acquired. If no printing operation has been performed between the most recent determination process and the current determination process, no ink will be ejected, and therefore, in the processes of S1810 and S1812, the respective values ​​are set to "0".

[0115] Thereafter, in S1814, the concentration estimate calculation unit 1710 calculates the concentration estimate of the ink in the circulation path 400 based on the evaporation amount acquired in S1808 and the consumption amount acquired in S1812, and ends this acquisition process. The technology for acquiring the concentration estimate of the ink in the circulation path based on the evaporation amount of ink per unit time and the consumption amount of ink consumed in the printing operation is a known technology, so a detailed description thereof will be omitted. For example, in order to simplify the calculation, the calculated concentration estimate is assumed to be a state after the ink in the circulation path that has been thickened by the evaporation amount is mixed with ink that has not been thickened and becomes uniform after a certain period of time. In this case, it actually takes some time for the ink that has evaporated from the nozzle and thickened to become uniform in the circulation path, but the calculation is deliberately performed under strict conditions for evaporation.

[0116] <Decision process> In the above configuration, the recording device 10 performs a determination process at a predetermined time interval to determine whether or not to perform a maintenance process including kogation control and concentration adjustment, and if so, to determine the mode of the maintenance process to be performed. This determination process is performed for each recording head 26. In this embodiment, kogation control refers to a process including kogation removal and aging. The time interval at which the determination process is performed varies depending on the characteristics of the ink used, the configuration of the circulation path 400, the configuration of the recording element substrate 428, and the like. In this embodiment, the recording device 10 performs the determination process at a predetermined time interval when the power is ON. The maintenance process of the mode determined by the determination process is performed at a predetermined timing. The predetermined time interval may be, for example, a one-minute interval, or may be changed appropriately to an interval of two minutes or more, an interval of 30 minutes, or the like.

[0117] In this embodiment, four modes, mode A, mode B, mode C, and mode D, can be executed as maintenance processing modes including kogation control and density adjustment. Specifically, mode A is a mode in which kogation control and density adjustment are executed continuously. Mode B is a mode in which only density adjustment is executed. Furthermore, mode C is a mode in which ink is ejected (for example, preliminary ejection, which is ejection of ink that does not contribute to recording) in a part of the area. Furthermore, mode D is a mode in which a negative pressure is applied from the outside to each nozzle to suck ink, and pressurized suction is performed to eject ink from each nozzle by pressurizing (the recording element is not driven). In addition to the above four modes, five modes including a mode "none", that is, no maintenance processing is executed, are determined in the determination process. Furthermore, the recording device 10 executes maintenance processing based on the mode determined in the determination process. When a mode is determined during a recording operation, the maintenance processing based on the determined mode is executed at a predetermined timing, such as the timing when a recording operation based on a job is completed or the timing when a recording operation on a recording medium being recorded is completed.

[0118] Fig. 19 is a flowchart showing the detailed processing contents of the determination processing. Fig. 20 is a flowchart showing the detailed processing contents of the update processing, which is a subroutine of the determination processing. A series of processes shown in the flowcharts of Figs. 19 and 20 is performed by the CPU of the engine controller 204 expanding program codes stored in the ROM of the engine controller 204 into the RAM of the engine controller and executing the programs. Alternatively, some or all of the functions of the steps in Figs. 19 and 20 may be performed by hardware such as an ASIC or an electric circuit.

[0119] When the determination process is started, first, in S1902, the CPU of the engine controller 204 (hereinafter, simply referred to as the "CPU") executes an update process for updating the density adjustment flag.

[0120] When the update process is started, first, in S2002, the CPU acquires an estimated ink concentration value V in the circulation path 400. In S2002, the above-mentioned acquisition process acquires the estimated ink concentration value V in the circulation path 400 at the time this process is being executed. Next, in S2004, the CPU determines whether the estimated ink concentration value V acquired in S2004 exceeds a threshold value Th_1. The threshold value Th_1 is a value smaller than the concentration value that requires concentration adjustment, and is, for example, a value that is a certain amount smaller than the lower limit of the ink concentration at which a deterioration in recording quality occurs.

[0121] If it is determined in S2004 that the concentration estimate V exceeds the threshold value Th_1, the CPU updates the concentration adjustment flag to ON in S2006 and proceeds to S1904, which will be described later. If it is determined in S2004 that the concentration estimate V does not exceed the threshold value Th_1, the CPU proceeds to S2008, where the CPU determines whether the concentration estimate V exceeds a threshold value Th_2. The threshold value Th_2 is a value that is a predetermined amount smaller than the threshold value Th_1.

[0122] If it is determined in S2008 that the concentration estimate V exceeds the threshold value Th_2, the CPU updates the concentration adjustment flag to ON in S2010 and proceeds to S1904, which will be described later. If it is determined in S2008 that the concentration estimate V does not exceed the threshold value Th_2, the CPU updates the concentration adjustment flag to OFF in S2012 and proceeds to S1904, which will be described later.

[0123] In this embodiment, when it is determined that the concentration estimation value V exceeds the threshold value Th_1 or the threshold value Th_2, the concentration adjustment flag is simply set to ON, but the present invention is not limited to this. For example, when the concentration estimation value V exceeds the threshold value Th_2, the user may be notified that the timing for performing the concentration adjustment is approaching, and the concentration adjustment flag may be updated to OFF. Alternatively, when the concentration estimation value V exceeds the threshold value Th_2, a warning screen may be displayed and the user may be allowed to select "execute" or "not execute" the concentration adjustment. In this case, when "execute" is selected, the concentration adjustment flag is set to ON, and when "not execute" is selected, the concentration adjustment flag is set to OFF. In addition, in this case, when the concentration estimation value V exceeds the threshold value Th_1, the concentration adjustment flag is forcibly set to ON. When the timing for performing the concentration adjustment differs, the ink concentration rate also changes, so if a target ink concentration is set, the ink discharge amount during the concentration adjustment must also be changed each time. In this embodiment, when it is determined that the concentration estimation value V exceeds the threshold value Th_1 or the threshold value Th_2, the concentration adjustment flag is simply set to ON. For this reason, in the update process, S2004 and S2006 may be omitted, and only the determination as to whether the threshold value Th_2 is exceeded may be performed, and the ON / OFF state of the density adjustment flag may be updated.

[0124] Returning to FIG. 19, when the updating of the density adjustment flag is completed, the process proceeds to S1904 where the CPU determines whether or not the density adjustment flag is ON. If it is determined in S1904 that the density adjustment flag is not ON, that is, that the density adjustment flag is OFF, the process proceeds to S1905 where the CPU determines the mode of the maintenance process to be executed as "none" and ends the determination process. If the mode of the maintenance process to be executed is determined to be "none" in the determination process, the maintenance process is not executed after the determination process.

[0125] Furthermore, if it is determined in S1904 that the density adjustment flag is ON, then in S1906 the CPU calculates the ink discharge amount D. In S1906, the ink discharge amount D, which is the amount of ink discharged from the circulation path 400 during density adjustment, is calculated. The ink discharge amount D is calculated based on the density estimate value V acquired in S2002 and the amount of ink circulating in the circulation path 400. Note that at this time, the ink discharge amount D is calculated so that the ink density in the circulation path 400 falls within a predetermined density range by supplying an amount of unevaporated ink corresponding to the ink discharge amount D from the main tank 402 after ink is discharged from the circulation path 400 by the ink discharge amount D. Note that the ink discharge amount D may always be constant without determining the ink density after density adjustment.

[0126] Next, in S1908, the CPU calculates the number of ejections (number of dots) P ​​for each recording element substrate 428 when the calculated ink ejection amount D is ejected from each nozzle of the recording head 26. Then, the process proceeds to S1910, where the CPU determines whether or not the maximum Pmax of the calculated ejection numbers P exceeds a threshold value K1. The threshold value K1 is a threshold value for determining whether or not to execute a process to remove kogation adhering to the upper protective layer 1310. The threshold value K1 is experimentally determined depending on the type of ink used, the configuration of the recording element substrate 428, and the like. Note that in this embodiment, as described above, 5×10 8 Therefore, in this embodiment, the threshold value K1 is set to, for example, 5×10 8, or a constant value less than this value.

[0127] If it is determined in S1910 that Pmax exceeds the threshold value K1, the process proceeds to S1912, where the CPU determines mode A, and then in S1914, it is determined whether the number of ejections P based on the ink discharge amount D is smaller than the number of ejections A during aging. In this embodiment, the dot number calculation unit 1716 calculates the number of ejections per nozzle in each recording element substrate 428. Therefore, the number of ejections P based on the ink discharge amount D is the number of ejections per nozzle when ink of the ink discharge amount D is ejected from each nozzle of each recording element substrate 428. Also, in this embodiment, from a state where no kogation is present, 5×10 5 Therefore, the number of ink shots A during aging is set to, for example, 5×10 5 , or a value close to this value. Note that this value is merely an example, and the number of ejections A is determined experimentally depending on the type of ink used, the configuration of the recording element substrate 428, and the like.

[0128] If it is determined in S1914 that the number of ejection shots P based on the ink ejection amount D is smaller than the number of ejection shots A, the process proceeds to S1916. In S1916, the CPU determines that ink is ejected in mode A under the driving conditions during aging and under the number of ejection shots A during aging, and ends this determination process. If it is determined in S1914 that the number of ejection shots P based on the ink ejection amount D is equal to or greater than the number of ejection shots A, the process proceeds to S1918. In S1918, the CPU determines that ink is ejected in mode A under the driving conditions during density adjustment and under the number of ejection shots P based on the ink ejection amount D, and ends this determination process. As described above, the driving conditions during aging are set to conditions that promote the adhesion of kogation to the upper protective layer 1310 more than the driving conditions during normal printing operations such as density adjustment.

[0129] Here, in the kogation control, after removing the kogation, ink is discharged by the number of ejections A during aging under the driving conditions for aging to perform aging. In the density adjustment, ink is discharged by the number of ejections P based on the ink ejection amount D under normal driving conditions, and then an amount of ink corresponding to the ejected ink, that is, an amount of ink based on the ink ejection amount D, is supplied from the main tank 402. For this reason, in mode A, in which kogation control and density adjustment are performed consecutively, the ink ejection in one process is used as the ink ejection in the other process for the ink ejection performed in both kogation control and density adjustment. In other words, in mode A, the ink ejection in one process is used as the ink ejection in the other process, and kogation control and density adjustment are performed consecutively.

[0130] That is, in mode A, after the kogation is removed, ink is ejected from each nozzle and discharged from the circulation path 400, and then an amount of ink corresponding to the amount of discharged ink is supplied from the main tank 402. Therefore, in mode A via S1916, after the kogation is removed, ink is ejected (discharged) by the number of ejections A during aging under the driving conditions for aging, and then an amount of ink corresponding to the number of ejections A is supplied from the main tank 402. Also, in mode A via S1918, after the kogation is removed, ink is ejected (discharged) by the number of ejections P based on the ink discharge amount D under the driving conditions for density adjustment, and then an amount of ink corresponding to the number of ejections P is supplied from the main tank 402.

[0131] In S1918, it is determined that ink is discharged in mode A under the driving conditions during density adjustment, the number of ejections P based on the ink discharge amount D, but this is not limited to this. For example, of the number of ejections P based on the ink discharge amount D, only the number of ejections A which is smaller than the number of ejections P is driven under the driving conditions during aging drive. After that, it may be determined that only the number of ejections equal to the difference between the number of ejections P and the number of ejections A is set as the driving conditions for the density adjustment value. This makes it possible to reliably ensure the amount of kogation adhesion during aging.

[0132] On the other hand, if it is determined in S1910 that Pmax does not exceed the threshold K1, the process proceeds to S1920, where the CPU determines whether Pmax is equal to or smaller than a threshold K2. The threshold K2 is a value smaller than the threshold K1, and is, for example, half the value of the threshold K1. In other words, in this embodiment, the threshold K1 is set to 5×10 8 Therefore, the threshold K2 is 2.5×10 8 It becomes.

[0133] If it is determined in S1920 that Pmax is not equal to or less than the threshold value K2, the process proceeds to S1922, where the CPU determines mode B and ends this determination process. That is, in mode B, ink is discharged from each nozzle at the number of shots P based on the ink discharge amount D to discharge ink from the circulation path 400, and then an amount of ink corresponding to the amount of discharged ink is supplied from the main tank 402, thereby executing normal concentration adjustment.

[0134] Furthermore, if it is determined in S1920 that Pmax is equal to or less than the threshold value K2, the process proceeds to S1924, where the CPU determines whether or not the deviation Pσ of the number of ejections P between the recording element substrates 428 is equal to or greater than a threshold value Thσ. In S1924, the standard deviation Pσ of the number of ejections P for each recording element substrate 428 is obtained, and it is determined whether or not this deviation is equal to or greater than a threshold value Thσ. The threshold value Thσ is the deviation when the number of ejections on the recording element substrate 428 is equal to or less than a certain number, for example, 1.0×10 8 In other words, in S1924, it is determined whether or not there is a recording element substrate 428 for which Pσ≧Thσ.

[0135] In S1924, if it is determined that Pσ≧Thσ, that is, there is a recording element substrate 428 for which Pσ≧Thσ is satisfied, the process proceeds to S1926, where the CPU determines the mode C and ends the determination process. That is, in mode C, a predetermined number of preliminary ejections are performed from the nozzles of a recording element substrate 428 with a small number of ejections that satisfies Pσ≧Thσ. Also, in S1924, if it is determined that Pσ≧Thσ is not satisfied, that is, there is no recording element substrate 428 for which Pσ≧Thσ is satisfied, the process proceeds to S1928, where the CPU determines the mode D and ends the determination process. That is, in mode D, in all recording element substrates 428, pressure suction is performed in which ink is sucked from the nozzles while pressure is applied without driving the recording elements 1118 to eject ink from the nozzles. In this way, in this embodiment, the engine controller 204 functions as a control unit that determines whether or not to execute a maintenance process including kogation control and density adjustment, and controls to determine the mode of the maintenance process to be executed.

[0136] <Action and effect> As described above, in recording apparatus 10, in mode A in which burnt control and density adjustment are performed, the discharge of ink in one of the burnt control and density adjustment processes also serves as the discharge of ink in the other process. This shortens the time required for the burnt control and density adjustment compared to when the burnt control and density adjustment are performed separately, making it possible to prevent a decrease in productivity in recording apparatus 10. In addition, because the amount of waste ink generated is reduced, it is possible to prevent an increase in production costs.

[0137] Furthermore, in the recording device 10, it is possible to execute different modes of maintenance processing depending on the number of ejections based on the concentration estimate value. This makes it possible to execute maintenance processing in the inner mode of the ejection operation depending on the concentration estimate value, making it possible to suppress the adhesion of unnecessary kogation to the upper protective layer 1310 and contributing to a longer life of the recording head 26.

[0138] Second embodiment Next, a recording device according to a second embodiment will be described with reference to Figures 21 and 22. In the following description, the same or corresponding configurations as those of the recording device according to the first embodiment described above will be denoted by the same reference numerals as those used in the first embodiment, and detailed description thereof will be omitted.

[0139] The second embodiment differs from the first embodiment in the following respects. First, when performing maintenance processing, mode A or mode B is selected based on the density estimation value. Also, if there is a print head 26 that has been determined to be in mode B, an update process is performed with a smaller threshold value for the print head 26 that has been determined to be in no mode, and based on the result of the update process, it is determined whether or not it is possible to switch to mode B. The determination process executed by the printing device 10 according to the second embodiment will be described in detail below.

[0140] <Decision process> Fig. 21 is a flowchart showing the detailed processing contents of the determination processing executed by the recording device 10 according to the second embodiment. Fig. 22 is a flowchart showing the detailed processing contents of the second update processing, which is a subroutine of the determination processing. A series of processes shown in the flowcharts of Figs. 21 and 22 are performed by the CPU of the engine controller 204 expanding program codes stored in the ROM of the engine controller 204 into the RAM of the engine controller and executing the programs. Alternatively, some or all of the functions of the steps in Figs. 21 and 22 may be executed by hardware such as an ASIC or an electric circuit.

[0141] When the determination process is started, first, in S2102, the CPU selects a print head 26 for which the mode has not been determined. That is, in S2102, among the print heads 26 provided in the recording device 10, any one of the print heads 26 for which the maintenance process mode has not yet been determined is selected. Then, in S2104, the CPU performs a first update process for the selected print head 26. Note that the specific process content of the first update process is the same as the update process of the first embodiment, so the description thereof will be omitted. Here, in the determination process of the second embodiment, the maintenance process modes to be determined are two types, mode A and mode B (strictly speaking, three types including the mode "none"). For this reason, the threshold value Th_1 used in the first update process is set to, for example, the lower limit value of the ink density at which a deterioration in recording quality occurs, or a value that is a predetermined amount smaller than the lower limit value.

[0142] Next, in S2106, the CPU determines whether the density adjustment flag is ON. If it is determined in S2106 that the density adjustment flag is OFF, the process proceeds to S2108, where the CPU determines the mode to be "none," and proceeds to S2126, which will be described later. If it is determined in S2106 that the density adjustment flag is ON, the CPU calculates the ink discharge amount D in S2110, and calculates the number of ejections P in S2112. The specific processing contents of S2110 and S2112 are the same as the processing of S1906 and S1908 described above.

[0143] Thereafter, in S2114, the CPU judges whether or not the maximum Pmax of the calculated ejection shot numbers P exceeds a threshold value K1. The specific processing content of S2114 is the same as the processing of S1910 described above. If it is judged in S2114 that Pmax does not exceed the threshold value K1, the process proceeds to S2116, where the CPU decides on mode B, and proceeds to S2126 described later. The specific processing content of S2116 is the same as the processing of S1922 described above.

[0144] Also, if it is determined in S2114 that Pmax exceeds the threshold value K1, the process proceeds to S2118, where the CPU determines the mode A, and then in S2120, it determines whether the number of ejection shots P based on the ink discharge amount D is smaller than the number of ejection shots A. If it is determined in S2120 that the number of ejection shots P based on the ink discharge amount D is smaller than the number of ejection shots A, the process proceeds to S2122. In S2122, the CPU determines that ink is ejected in the mode A under the driving conditions during aging and the number of ejection shots A during aging, and proceeds to S2126, which will be described later. If it is determined in S2120 that the number of ejection shots P based on the ink discharge amount D is equal to or larger than the number of ejection shots A, the process proceeds to S2124. In S2124, the CPU determines that ink is ejected in the mode A under the driving conditions during density adjustment and the number of ejection shots P based on the ink discharge amount D, and proceeds to S2126, which will be described later. The specific processing contents from S2120 to S2124 are the same as the processing contents from S1914 to S1918 described above.

[0145] In S2126, the CPU determines whether there is a print head 26 for which the mode has not been determined. That is, in S2126, it is determined whether there is a print head 26 for which the maintenance process mode has not yet been determined among the print heads 26 provided in the recording device 10. If it is determined in S2126 that there is a print head 26 for which the mode has not been determined, the process returns to S2102. If it is determined in S2126 that there is no print head 26 for which the mode has not been determined, the process proceeds to S2128, where the CPU determines whether there is a print head 26 for which mode B has been determined.

[0146] If it is determined in S2128 that there is no recording head 26 determined to be in mode B, this determination process ends. If it is determined in S2128 that there is a recording head 26 determined to be in mode B, the process proceeds to S2130, where the CPU extracts a recording head 26 determined to be in mode "none." If there is no recording head 26 determined to be in mode "none" in S2130 and extraction is not possible, this determination process ends.

[0147] Next, in S2132, the CPU selects a recording head 26 that has not yet undergone the second update process (described later) from among the extracted recording heads 26. Then, in S2134, the CPU executes the second update process for the recording head 26 selected in S2132.

[0148] When the second update process is started, first, in S2202, the CPU acquires an estimated density value V of the ink in the circulation path 400. The specific process content of S2202 is the same as S2002 described above. Next, in S2204, the CPU determines whether the estimated density value V acquired in S2202 exceeds a threshold value Th_3. The threshold value Th_3 is, for example, a value obtained by multiplying the threshold value Th_1 by 0.8. Note that the threshold value Th_3 is not limited to the value obtained by multiplying the threshold value Th_1 by 0.8. The threshold value Th_3 may be a value smaller than the threshold value Th_1 and close to the threshold value Th_1, and may be a value of a predetermined ratio to the threshold value Th_1. Note that this process may be performed in S2136 described later, as long as it is possible to extract a print head 26 that has an estimated density value that is considered reasonable from the viewpoint of cost and the like even if density adjustment is performed, and Th_3 may be set appropriately.

[0149] If it is determined in S2204 that the estimated density value V exceeds the threshold value Th_3, the CPU updates the density adjustment flag to ON in S2206 and proceeds to S2136, which will be described later. If it is determined in S2204 that the estimated density value V does not exceed the threshold value Th_3, the CPU updates the density adjustment flag to OFF in S2208 and proceeds to S2136, which will be described later.

[0150] Returning to FIG. 21, when the second update process is completed, in S2136, the CPU judges whether or not the density adjustment flag is ON. The specific process content of S2136 is the same as S2106 described above. If it is judged in S2136 that the density adjustment flag is OFF, the process proceeds to S2140 described later. That is, the process proceeds without changing the mode. If it is judged in S2136 that the density adjustment flag is ON, the process proceeds to S2138, where the CPU determines mode B for the recording head 26 selected in the most recent S2132. That is, this process changes the mode of the recording head 26 selected in the most recent S2132 from "none" to "B."

[0151] Then, in S2140, it is determined whether or not there is a recording head 26 that has not yet executed the second update process among the recording heads 26 extracted in S2130. If it is determined in S2140 that there is a recording head 26 that has not yet executed the second update process, the process returns to S2132. If it is determined in S2140 that there is not a recording head 26 that has not yet executed the second update process, this determination process ends.

[0152] <Action and effect> As described above, in recording apparatus 10, in mode A in which burnt control and density adjustment are performed, the discharge of ink in one of the burnt control and density adjustment processes also serves as the discharge of ink in the other process. This shortens the time required for the burnt control and density adjustment compared to when the burnt control and density adjustment are performed separately, making it possible to prevent a decrease in productivity in recording apparatus 10. In addition, because the amount of waste ink generated is reduced, it is possible to prevent an increase in production costs.

[0153] Furthermore, when there is a recording head 26 for which mode B, which performs only density adjustment, is determined, among the recording heads 26 for which mode "none" is determined, the recording heads 26 for which it is reasonable to perform density adjustment are also determined to be in mode B. This reduces the number of times mode B, which performs only density adjustment, and improves productivity.

[0154] (Other embodiments) The above-described embodiment may be modified as shown in the following (1) to (6).

[0155] (1) In the second embodiment, the maintenance process mode is determined to be mode A, mode B, or mode "none" in the process prior to S2126 in the determination process, but this is not limited to this. As in the first embodiment, the maintenance process mode may be determined from mode A, mode B, mode C, mode D, and mode "none." In this case, the process from S2126 onwards is the same as that in the second embodiment.

[0156] (2) In the above embodiment, the recording device 10 is a so-called full-line type recording device that uses a long recording head that covers the entire width of the recording area on the recording medium, but is not limited to this. It may also be a so-called serial scan type recording device that uses a recording head that ejects ink while moving in a direction intersecting the transport direction of the recording medium.

[0157] (3) In the above embodiment, the determination process uses a concentration estimate value obtained by estimating the concentration of ink circulating in the circulation path 400, but this is not limited to the above. A configuration capable of measuring the concentration of ink in the circulation path 400 may be provided, and the determination unit may determine the maintenance process mode using the concentration value measured by the configuration.

[0158] (4) In the above embodiment, the control unit 200 (engine controller 204) of the recording device 10 executes the determination process for determining the maintenance process mode including kogation control and concentration adjustment, but this is not limited to the above. The determination process may be executed in an external device connected to the recording device 10, such as the higher-level device HC2 or the host device HC1, based on information output from the recording device 10.

[0159] (5) The present invention can also be realized by a process in which a program for realizing one or more of the functions of the above-described embodiment is supplied to a system or device via a network or a print medium, and one or more processors in the computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) for realizing one or more of the functions.

[0160] (6) The above embodiment and the various configurations shown in (1) to (5) above may be combined as appropriate.

[0161] The disclosure of the above embodiment includes the following configurations and methods. (Configuration 1) a recording means for ejecting ink from a nozzle using thermal energy generated by a heating element; a circulation path through which ink is circulated so as to supply ink to the recording means and to supply the ink discharged from the recording means back to the recording means; A recording device characterized by having a control means capable of executing a first control of ejecting and discharging ink from the nozzles to cause kogation to adhere to a protective layer covering the heating elements, and a second control of ejecting and discharging ink from the nozzles to discharge ink from the circulation path and supplying an amount of ink corresponding to the amount discharged to the circulation path, thereby adjusting the concentration of ink in the circulation path, when the first control and the second control are executed successively, so that the discharge of ink in one control serves as the discharge of ink in the other control. (Configuration 2) 2. The recording apparatus according to configuration 1, wherein in the first control, after removing kogation caused by a recording operation, the kogation is caused to adhere to the protective layer. (Configuration 3) 3. The recording apparatus according to configuration 1 or 2, wherein in the second control, a discharge amount of ink discharged from the circulation path is calculated based on a concentration of ink in the circulation path. (Configuration 4) 4. The recording apparatus according to configuration 3, wherein the density is an estimated value. (Configuration 5) The recording device described in configuration 3 or 4, wherein the control means determines either a first mode in which the first control and the second control are executed successively, or a second mode in which the second control is executed, based on the number of ink ejections from the nozzles according to the discharge amount. (Configuration 6) The recording device described in configuration 5, characterized in that the control means sets the number of ink shots ejected from the nozzle when the first control and the second control are executed consecutively to a first number of shots for adhering kogation in the first control or a second number of shots based on the discharge amount. (Configuration 7) In the first control, the heating elements are driven under second driving conditions that are more likely to cause kogation than the first driving conditions during a recording operation; The control means when the number of ejection shots of ink ejected from the nozzle when the first control and the second control are successively executed is set to the first number of ejection shots, the heating element is driven under the second drive condition; The recording device according to configuration 6, characterized in that when the number of ink shots ejected from the nozzle when the first control and the second control are executed successively is set to the second number of shots, the heating element is driven under the first drive condition. (Configuration 8) In the first control, the heating elements are driven under second driving conditions that are more likely to cause kogation than the first driving conditions during a recording operation; The control means when the number of ejection shots of ink ejected from the nozzle when the first control and the second control are successively executed is set to the first number of ejection shots, the heating element is driven under the second drive condition; The recording device described in configuration 6, characterized in that when the number of ink shots ejected from the nozzle when the first control and the second control are executed successively is set to the second number of shots which is greater than the first number of shots, the heating element is driven under the second driving condition for the first number of shots, and the heating element is driven under the first driving condition for the difference between the first number of shots and the second number of shots. (Configuration 9) In the recording means, a plurality of substrates each having the heating element are arranged, the control means is further capable of executing a third control for executing a preliminary ejection, which is an ejection of ink that does not contribute to recording, for each of the substrates, and a fourth control for executing a pressurized suction, which applies a negative pressure from the outside to the nozzles to suck ink, while applying pressure to the nozzles to eject ink from the nozzles, The control means The recording apparatus according to configuration 3 or 4, characterized in that it determines whether to execute one of a first mode in which the first control and the second control are executed consecutively, a second mode in which the second control is executed, a third mode in which the third control is executed, and a fourth mode in which the fourth control is executed, depending on the maximum number of ink ejections from the nozzles for each substrate based on the discharge amount. (Configuration 10) The control means determining whether to execute the first mode based on the maximum number of ejections and a first threshold value; The recording apparatus according to configuration 9, wherein execution of the second mode is determined based on the maximum number of ejections and a second threshold value that is smaller than the first threshold value. (Configuration 11) 11. The recording apparatus according to configuration 10, wherein the second threshold value is half the value of the first threshold value. (Configuration 12) The recording apparatus according to any one of configurations 9 to 11, characterized in that the control means determines whether to execute either the third mode or the fourth mode based on the bias in the number of ink shots ejected from the nozzles for each substrate. (Configuration 13) The recording apparatus according to any one of configurations 1 to 12, characterized in that the control means determines whether or not to execute a maintenance process including the first control and the second control based on the concentration of ink in the circulation path. (Configuration 14) When performing the maintenance process, the control means When the concentration of ink in the circulation path exceeds a first value, the maintenance process is forcibly performed; The recording device according to configuration 13, characterized in that when it is determined that the density is equal to or less than the first value and exceeds a second value smaller than the first value, execution of the maintenance process can be selected. (Configuration 15) The recording means is provided in plurality, The control means for each of the recording means, it is possible to determine whether or not to execute a maintenance process including the first control and the second control based on the concentration of ink in the circulation path and a first threshold value, and, if the maintenance process is to be executed, to determine either a first mode in which the first control and the second control are executed successively or a second mode in which the second control is executed; The recording device according to any one of configurations 1 to 4, characterized in that when there is a recording means for which the second mode has been determined, the recording means for which it has been determined not to perform the maintenance process is set to the second mode based on the concentration of ink in the circulation path and a second threshold value that is a predetermined percentage of the first threshold value. (Configuration 16) a recording means for ejecting ink from a nozzle using thermal energy generated by a heating element; a circulation path through which ink is circulated so that ink discharged from the recording means is supplied to the recording means again, the control method for a recording apparatus comprising the steps of: A control method characterized by the fact that when a first control in which ink is ejected and discharged from the nozzle to cause kogation to adhere to the protective layer covering the heat generating element, and a second control in which ink is ejected and discharged from the nozzle to discharge ink from the circulation path and an amount of ink corresponding to the amount discharged is supplied to the circulation path to adjust the concentration of ink in the circulation path are successively executed, the discharge of ink in one control also serves as the discharge of ink in the other control. (Configuration 17) A program for causing a computer to execute the control method of configuration 16. [Explanation of symbols]

[0162] 10 Recording Device 26 Recording head 204 Engine Controller 400 Circulation Route 1118 Recording element

Claims

1. a recording means for ejecting ink from a nozzle using thermal energy generated by a heating element; a circulation path through which ink is circulated so as to supply ink to the recording means and to supply the ink discharged from the recording means back to the recording means; A recording device characterized by having a control means capable of executing a first control of ejecting and discharging ink from the nozzles to cause kogation to adhere to a protective layer covering the heating elements, and a second control of ejecting and discharging ink from the nozzles to discharge ink from the circulation path and supplying an amount of ink corresponding to the amount discharged to the circulation path, thereby adjusting the concentration of ink in the circulation path, when the first control and the second control are executed successively, so that the discharge of ink in one control also serves as the discharge of ink in the other control.

2. 2. The recording apparatus according to claim 1, wherein in the first control, after removing kogation caused by a recording operation, the kogation is caused to adhere to the protective layer.

3. 2. The recording apparatus according to claim 1, wherein in the second control, a discharge amount of ink discharged from the circulation path is calculated based on a concentration of ink in the circulation path.

4. 4. The recording apparatus according to claim 3, wherein the density is an estimated value.

5. The recording device according to claim 3, wherein the control means determines either a first mode in which the first control and the second control are executed successively, or a second mode in which the second control is executed, based on the number of ink ejections from the nozzles corresponding to the discharge amount.

6. The recording device according to claim 5, characterized in that the control means sets the number of ink shots ejected from the nozzle when the first control and the second control are executed successively to a first number of shots for adhering kogation in the first control or a second number of shots based on the discharge amount.

7. In the first control, the heating elements are driven under second driving conditions that are more likely to cause kogation than the first driving conditions during a recording operation; The control means when the number of ejection shots of ink ejected from the nozzle when the first control and the second control are successively executed is set to the first ejection number, the heating element is driven under the second drive condition; The recording device according to claim 6, characterized in that when the number of ink shots ejected from the nozzle when the first control and the second control are executed successively is set to the second number of shots, the heating element is driven under the first driving condition.

8. In the first control, the heating elements are driven under second driving conditions that are more likely to cause kogation than the first driving conditions during a recording operation; The control means when the number of ejection shots of ink ejected from the nozzle when the first control and the second control are successively executed is set to the first number of ejection shots, the heating element is driven under the second drive condition; The recording device according to claim 6, characterized in that when the number of ink shots ejected from the nozzle when the first control and the second control are executed successively is set to the second number of shots which is greater than the first number of shots, the heating element is driven under the second driving conditions for the first number of shots, and the heating element is driven under the first driving conditions for the difference between the first number of shots and the second number of shots.

9. In the recording means, a plurality of substrates each having the heating element are arranged, the control means is further capable of executing a third control for executing a preliminary ejection, which is an ejection of ink that does not contribute to recording, for each of the substrates, and a fourth control for executing a pressurized suction, which applies a negative pressure from the outside to the nozzles to suck the ink, while applying pressure to the nozzles to eject the ink from the nozzles, The control means The printing apparatus according to claim 3, characterized in that it determines whether to execute one of a first mode in which the first control and the second control are executed consecutively, a second mode in which the second control is executed, a third mode in which the third control is executed, and a fourth mode in which the fourth control is executed, depending on the maximum number of ink ejections from the nozzles for each substrate based on the ejection amount.

10. The control means determining whether to execute the first mode based on the maximum number of ejections and a first threshold value; 10. The recording apparatus according to claim 9, wherein execution of the second mode is determined based on the maximum number of ejections and a second threshold value that is smaller than the first threshold value.

11. 11. The recording apparatus according to claim 10, wherein the second threshold value is half the value of the first threshold value.

12. 10. The printing apparatus according to claim 9, wherein the control means determines whether to execute either the third mode or the fourth mode based on a deviation in the number of ink shots ejected from the nozzles for each of the substrates.

13. 2. The recording apparatus according to claim 1, wherein the control unit determines whether or not to execute a maintenance process including the first control and the second control based on the concentration of ink in the circulation path.

14. When performing the maintenance process, the control means When the concentration of the ink in the circulation path exceeds a first value, the maintenance process is forcibly performed; 14. The recording apparatus according to claim 13, wherein execution of the maintenance process is selectable when it is determined that the density is equal to or less than the first value and exceeds a second value that is smaller than the first value.

15. The recording means is provided in plurality, The control means for each of the recording means, it is possible to determine whether or not to execute a maintenance process including the first control and the second control based on the concentration of ink in the circulation path and a first threshold value, and, if the maintenance process is to be executed, to determine a first mode in which the first control and the second control are executed successively and a second mode in which the second control is executed; The recording device according to claim 1, characterized in that when a recording means determined to be in the second mode is present, the recording means for which it has been determined that the maintenance process should not be performed is determined to be in the second mode based on the concentration of ink in the circulation path and a second threshold value that is a predetermined percentage of the first threshold value.

16. a recording means for ejecting ink from a nozzle using thermal energy generated by a heating element; a circulation path through which ink is circulated so that ink discharged from the recording means is supplied to the recording means again, A control method characterized by the fact that, when successively executing a first control in which ink is ejected and discharged from the nozzle to cause kogation to adhere to the protective layer covering the heat generating element, and a second control in which ink is ejected and discharged from the nozzle to discharge ink from the circulation path and an amount of ink corresponding to the amount discharged is supplied to the circulation path to adjust the concentration of ink in the circulation path, the discharge of ink in one control also serves as the discharge of ink in the other control.

17. A program for causing a computer to execute the control method according to claim 16.

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