Recording apparatus and recording method

Abstract

To improve recording accuracy in a recording head capable of circulating a liquid.SOLUTION: A printing apparatus includes a print head having a circulation unit configured to circulate ink containing a color material, an estimation unit configured to estimate a concentration of the color material in the ink circulating in the print head based on a consumption amount of the ink in the print head in a predetermined period and a sedimentation amount of the color material in the print head, and a processing unit configured to execute predetermined processing in accordance with the estimated concentration estimated by the estimation unit.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present disclosure relates to a recording device capable of circulating ink within a recording head. [Background technology]

[0002] Inkjet printheads are used in printing devices to print by ejecting liquid such as ink. A printing device equipped with an inkjet printhead is configured to receive ink from an ink tank via a supply flow path and print an image based on image data specified by a user.

[0003] Some recording heads circulate liquid to prevent colorant settling and ink thickening. For example, Japanese Patent Application Laid-Open No. 2022-334 proposes a recording device that circulates liquid within the recording head using two circulation means: a circulation pump and a pressure control unit. By using a recording head with such a circulation configuration, it is possible to use liquids such as white ink, which have fast colorant settling, in the recording device with high productivity. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-334 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, market demands for smaller device sizes have led to the miniaturization and complexity of circulation channels within print heads. As a result, it has become difficult to maintain a constant or higher flow rate in all channels within the print head. This is because complex channels inevitably contain stagnant areas where the flow rate drops below a certain level. In particular, with liquids that settle quickly, such as white ink, settling can occur even when the liquid within the print head is circulated by a circulation device, resulting in uneven concentration of the liquid.

[0006] Therefore, an object of the present disclosure is to improve the printing accuracy in a print head capable of circulating liquid. [Means for solving the problem]

[0007] A recording device according to one aspect of the present disclosure is characterized by comprising a recording head having a circulation means for circulating ink containing colorant, an estimation means for estimating the concentration of colorant in the ink circulating within the recording head based on the amount of ink consumed by the recording head over a predetermined period and the amount of colorant settling in the recording head, and a processing means for performing a predetermined process in accordance with the estimated concentration estimated by the estimation means. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to improve the accuracy of printing in a print head capable of circulating liquid. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a recording device. [Figure 2] FIG. 2 is a schematic diagram of a recording head of the recording apparatus. [Figure 3] FIG. 3 is a schematic diagram of a circulation flow path inside the recording head. [Figure 4] FIG. 2 is a diagram illustrating the configuration of a circulation flow path inside a recording head. [Figure 5] FIG. 2 is a block diagram of a control system of the printing system of the printing apparatus. [Figure 6]FIG. 2 is an enlarged schematic view of a circulation flow path inside the recording head. [Figure 7] 10 is a graph showing the relationship between the pigment concentration of ink inside the print head and elapsed time. [Figure 8] 10 is a graph showing the relationship between the amount of sedimentation inside the recording head and the elapsed time. [Figure 9] 10 is a flowchart of a process for predicting ink consumption in a print head. [Figure 10] FIG. 10 is a sequence diagram of a process for deriving the pigment concentration of ink in a print head. [Figure 11] 10 is a flowchart of a correction process. [Figure 12] 10 is a flowchart of a correction process. [Figure 13] 10 is a flowchart of a correction process. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Embodiment 1> Hereinafter, examples of embodiments of the present disclosure will be described with reference to the drawings. However, the following description does not limit the scope of the present disclosure. As an example, the present embodiments employ a thermal method in which a heating element generates bubbles to eject liquid, but the present disclosure can also be applied to liquid ejection heads employing a piezo method or various other liquid ejection methods. In the embodiment described below, the liquid ejected by the recording apparatus is a pigment ink containing a pigment as a coloring material.

[0011] Furthermore, the present invention is not limited to this, and may be applied to any device having the same function as the described configuration, such as a pump or pressure adjusting means.

[0012] In order to briefly explain the features of the embodiments, first, an outline of the device configuration, head configuration, etc. common to the embodiments will be described in detail. Next, the processing flow of the present embodiment will be described according to multiple embodiments.

[0013] (Description of recording device) 1 is a schematic perspective view of an inkjet recording apparatus according to the present embodiment. The inkjet recording apparatus of this example is a so-called serial type recording apparatus that records an image by reciprocating a recording head 1 in the recording width direction of a recording medium 5.

[0014] The recording head 1 is an inkjet recording head having multiple nozzle rows each consisting of a plurality of ejection ports capable of ejecting ink, and is detachably mounted on a carriage 2. The carriage 2 moves back and forth in the main scanning direction indicated by the arrow X. Specifically, the carriage 2 is movably supported along a guide rail 3 extending in the main scanning direction, and is connected to an endless belt 4 that moves parallel to the guide rail 3. The endless belt 4 is moved back and forth by the driving force of a carriage motor (CR motor), causing the recording head 1 to move back and forth in the main scanning direction together with the carriage 2. A recording medium 5 is transported by transport rollers 6 in the sub-scanning direction indicated by the arrow Y, which intersects the main scanning direction (orthogonal in the case of FIG. 1).

[0015] A plurality of ink supply tubes 7 corresponding to a plurality of ink colors are connected to the recording head 1, and the supply tubes 7 are connected to ink tanks (not shown) that hold ink of each color, forming ink supply channels. Each color of ink supplied to the recording head 1 by the ink supply channels can be supplied independently to each corresponding nozzle row of the recording head 1.

[0016] Such a serial type recording device records an image on a recording medium 5 by repeating a recording scan in which the carriage 2 moves in the main scanning direction together with the recording head 1 while ejecting ink from the recording head 1, and an operation to transport the recording medium 5 in the sub-scanning direction. The main body of the recording device is also equipped with a recovery processing device 9 for maintaining a good ink ejection state of the recording head 1. The recovery processing device 9 is equipped with a capping mechanism that can cover the ejection ports of the recording head 1 with a cap, and a pump mechanism that can suck ink from the ejection ports of the recording head 1 through the cap. This makes it possible to perform an ink suction operation from the ejection ports as a maintenance operation.

[0017] (Explanation of recording head configuration) 2 is an exploded perspective view showing the recording head 1. The recording head 1 includes an ink circulation unit 21 and a recording element unit 22 that receives ink, which is a recording liquid, from the ink circulation unit 21 and ejects the ink onto a recording medium 5.

[0018] 2 shows a recording head 1 that can accommodate four types of ink. Four liquid connector insertion ports 23 are provided in the head housing 29 corresponding to the respective ink supply tubes 7, and individual supply paths are formed.

[0019] The recording element unit 22 is composed of two ejection modules 26, a first support member 24, a second support member 25, an electric wiring member (electric wiring tape) 27, and an electric contact substrate 28. The ejection module 26 of the recording element unit 22 includes a substrate made of silicon (hereinafter referred to as a silicon substrate) and an energy generating element provided on one side of the silicon substrate to generate energy used to eject liquid. In this embodiment, a plurality of heat generating resistor elements (heaters) are used as the energy generating elements, and electric wiring for supplying power to each heat generating resistor element is formed on the silicon substrate by a film formation technique. A flow path member is laminated on the silicon substrate by a photolithography technique, and the flow paths form a plurality of ink flow paths corresponding to the heat generating resistor elements and pressure chambers provided with a plurality of ejection ports for ejecting ink. An ink supply port and an ink recovery port for supplying ink to the plurality of ink flow paths are opened on the back surface of the silicon substrate.

[0020] The ejection module 26 is adhesively fixed to a first support member 24 that has an ink supply port and an ink recovery port. A second support member 25 that has an opening is adhesively fixed to the first support member 24. An electrical wiring member 27 is held on the second support member 25 so as to be electrically connected to the recording element substrate. The electrical wiring member 27 supplies an electrical signal for ejecting ink to the ejection module 26.

[0021] 3 is a diagram showing the flow path configuration of the recording head 1. Two ejection modules 26 are provided with individual supply flow paths 32 and individual recovery flow paths 33 so that ink circulates to ejection ports 31 provided in each pressure chamber. The individual supply flow paths 32 and individual recovery flow paths 33 are widened to the width of the ink circulation unit 21 by the flow paths of the first support member 24, and are connected to the ink circulation unit 21 of each color by a joint member 34. In addition, an electrical wiring member 27 is supported by a second support member 25 and is electrically connected to the ejection module 26. Supply ports 51 to 54 and recovery ports 56 to 59 of each color are formed in the joint member 34, and are connected to the ink circulation unit 21 for supplying and recovering ink.

[0022] (Explanation of the internal circulation structure of the head) FIG. 4 is a schematic diagram of the flow paths for one color within the print head 1. The arrows in the figure indicate the direction of ink flow. Ink supplied from an ink tank is pressurized by a pressure pump provided in the printing apparatus body, passes through a foreign matter collection filter 41 under positive pressure, and is supplied to a first liquid chamber 49 equipped with a first pressure adjustment means 42. The first liquid chamber 49 is a space that can hold ink that has passed through the foreign matter collection filter 41 and then depressurized by the first pressure adjustment means 42. The ink held in the first liquid chamber 49 flows to a supply flow path 43 and a bypass flow path 44. The first liquid chamber 49 is relatively easy to make large. For this reason, a space called a foam buffer is typically provided above the first liquid chamber 49 to collect foam and prevent it from flowing below the head. The depressurized ink is supplied to the ejection module 26 via the supply flow path 43 and then to a pressure chamber 48 connected to the ejection port 31. Unejected liquid is supplied to a second liquid chamber 50 via a recovery flow path 45. The second liquid chamber 50 is a space that holds ink that has passed through the bypass flow path 44 or the recovery flow path 45 and whose pressure has been adjusted by the second pressure adjustment means 46. A circulation pump 47 is provided downstream of the second liquid chamber 50, and returns the liquid to the first liquid chamber 49. The supply flow path 43 is connected to the individual supply flow paths 32 through a joint member 34 (see FIG. 3), and the individual recovery flow path 33 is connected to the recovery flow path 45 through the joint member 34. This allows a complete circulation path to be configured within the recording head 1.

[0023] (Control unit configuration of recording device) Figure 5 shows an example of the configuration of the control circuit of the printing apparatus in this embodiment. In Figure 5, PPI 501 stands for programmable peripheral interface, and receives printing information signals, including command signals and print data, sent from a host computer 500 and transfers them to MPU 502. It also sends printing apparatus status information to the host computer 500 as needed. It also performs input / output with a console 506, which includes a setting input unit through which the user can set various settings for the printing apparatus and a display unit that displays messages to the user. It also receives signal inputs from a group of sensors 507, including a home position sensor that detects when the print head 1 is in its home position and a capping sensor.

[0024] An MPU (microprocessing unit) 502 controls each component of the printing apparatus in accordance with a control program stored in a control ROM 505. A RAM 503 stores received signals or is used as a work area for the MPU 502, and also temporarily stores various data. When the printing apparatus is powered off, the various data stored in the RAM 503 is transferred to the control ROM 505, where the values ​​are saved. When the power is turned on, the values ​​of the various data are read into the RAM 503. A print buffer 521 stores print data expanded in the RAM 503, etc. The print buffer 521 has a capacity for printing multiple lines. In addition to various control programs, the control ROM 505 can also store fixed data corresponding to data used in the control process described below (for example, data related to the elapsed time since ink refilling and the increase in sedimentation amount, which are essential components of this embodiment). These components are controlled by the MPU 502 via an address bus 517 and a data bus 518.

[0025] Motor drivers 514, 515 and 516 are motor drivers for driving the capping motor 513, the carriage motor 509 and the paper feed motor 510, respectively, under the control of the MPU 502.

[0026] The head driver 511 is a driver for driving the electrothermal conversion elements of the printhead 1 in response to print information signals. The temperature and humidity sensor 522 is a temperature and humidity sensor for detecting the environmental temperature and humidity in the installation environment of the printing apparatus main body. The power supply unit 520 is a power supply unit that supplies power to each of the above units and has an AC adapter and a battery as a driving power supply device.

[0027] In a recording system consisting of the recording device 1 and a host computer 500 that supplies recording information signals to the recording device 1, when the host computer 500 transmits recording data via a network or the like, a required command is added to the beginning of the data. The command may include, for example, the type of recording medium (plain paper, overhead projector sheet, glossy paper, etc., as well as special recording media such as transfer film, cardboard, and banner paper) on which the recording is to be performed. Other commands may also include the medium size (A0, A1, A2, B0, B1, B2, etc.), the recording quality (draft, high quality, medium quality, specific color emphasis, monochrome / color, etc.), and whether or not automatic object detection is enabled. Furthermore, if a configuration is adopted in which a treatment liquid is applied to improve ink fixation on the recording medium, information specifying whether or not the treatment liquid is to be applied may also be transmitted as a command.

[0028] In response to these commands, the printing apparatus reads the data necessary for printing from the aforementioned ROM 505 and performs printing based on that data. Examples of data include the number of printing passes when performing multi-pass printing, the amount of ink applied per unit area of ​​the printing medium, and the printing direction. Other data include the type of mask used for thinning out data when performing multi-pass printing, and drive conditions based on the temperature sensor detection value within the printhead 1 (for example, the shape and application time of the drive pulse applied to the heat generating element). Other data include the dot size, printing medium transport conditions, the number of colors used, and even the carriage speed.

[0029] Although the image forming apparatus having the above configuration has been described as an example, the configuration described here is merely one example of an apparatus configuration for realizing the present invention. It goes without saying that the present invention is applicable even if, for example, the number of recording inks or the number of control units is different.

[0030] In addition, this embodiment will be described using as an example a so-called serial recording device in which a recording head moves relative to a recording medium to form an image. However, the focus of this embodiment is the ink settling phenomenon that occurs inside the circulation flow path, and is not limited to serial recording devices. This embodiment can also be applied to so-called full multi-head recording devices in which the head is fixed and the recording medium is transported, which have been developed in response to recent demands for high productivity. Furthermore, in the case of full multi-head devices, device configurations in which one ink color is used per recording head are also being developed, and it goes without saying that this embodiment can also be applied to such configurations.

[0031] In this embodiment, a configuration in which the print head 1 has a circulation pump 47 and ink is circulated inside the head will be described. This is because a configuration in which circulation is performed inside the head has narrower liquid flow paths, including the flow paths and pump, and is more susceptible to the effects of bubbles. However, in actual printing apparatuses, the circulation system tends to be large, so a configuration in which a pump is provided separately from the head and ink is circulated can also be considered. This embodiment is an invention that addresses the problem of sedimentation inside the flow paths, and it goes without saying that this is not dependent on the location of the circulation pump 47. It goes without saying that the present invention is applicable whether circulation is performed only in the head or whether a circulation path including the main body is included.

[0032] (Processing to derive concentration reduction due to ink sedimentation) Even in a print head with an ink circulation configuration like the one in this embodiment, there are inks that are prone to settling. For example, in white inks that use titanium oxide, which has a high specific gravity, as a pigment component, settling occurs in the so-called stagnation area, where the circulation speed in the circulation flow path is slower than in other areas.

[0033] Figure 6 shows a portion of the circulation flow path of the print head shown in detail in Figure 3. Figure 6 illustrates two of the multiple flow paths formed within the first support member 24, and the blackened areas in the figure are, for example, stagnation areas 60 and 61. As mentioned above, the circulation flow path of the print head 1 is complex, and stagnation areas in the flow path are unavoidable. If sedimentation occurs in such a stagnation area, the pigment concentration of the ink supplied to the pressure chambers 48 and the ejection ports 31 will be lower than normal, and therefore, if printing is performed on a print medium in this state, image unevenness may occur.

[0034] FIG. 7 shows the change in pigment concentration when the print head 1 of this embodiment is filled with white ink. The pigment concentration shown in FIG. 7 is the pigment concentration of the ink filled into the print head 1 and capable of being discharged from the print head. Even if the ink filled into the print head 1 continues to circulate within the print head 1, as shown in FIG. 7, sedimentation in stagnation areas progresses over time since filling, and the pigment concentration of the ink actually ejected decreases from the pigment concentration N0 [%] of the ink initially filled. However, as shown in FIG. 7, after time T1 has passed, the ink sedimentation progresses to the point where the stagnation areas of the print head flow paths are filled with sediment, and the sedimentation stops at a decrease in pigment concentration N1 [%].

[0035] It has also been confirmed that the sediment that settles in the stagnant area does not move after settling but remains in place, and that it has not been confirmed that the sediment in the stagnant area moves even when recording operations or maintenance are performed.

[0036] 7 also shows the decrease in pigment concentration when ink is continuously circulated within the recording head 1 after the recording head 1 is filled with ink. If the circulation is stopped, the rate at which the pigment settles is faster than when it is circulating, and the rate at which the pigment concentration decreases is faster than the rate shown in FIG.

[0037] The following describes a method for deriving the pigment concentration of the ink ejected by the print head 1. The concentration is obtained by the MPU 502 performing a process for predicting the amount of sedimentation increase, a process for predicting the amount of ink consumption, and a process for deriving the pigment concentration based on the information stored in the control ROM 505.

[0038] The sedimentation amount increase prediction process predicts the amount of sedimentation from the time elapsed since ink was filled into the print head 1. The prediction process is performed by the MPU 502. The MPU 502 measures the time elapsed since ink was filled, and estimates the amount of sedimentation from the measured elapsed time based on the data on the amount of sedimentation over time stored in the ROM 505.

[0039] Figure 8 shows the relationship between the amount of pigment sedimentation and the elapsed time when ink circulation continues after the print head is filled with ink. It has been confirmed that after time T1 [s] has elapsed, the amount of sedimentation inside print head 1 saturates at Y0 [mg] and the amount of sedimentation does not increase thereafter. For example, the increase in sedimentation amount Ymn when time has elapsed from Tm to Tn can be estimated using Ymn = Yn - Ym.

[0040] The elapsed time may be measured separately for the time when circulation is performed and the time when circulation is not performed. In this way, ROM 505 stores data on the change in sedimentation amount separately for the time when circulation is performed and the time when circulation is not performed, and by adding up the increase in sedimentation amount for each elapsed time, the increase in sedimentation amount for a certain elapsed time can be estimated.

[0041] In this embodiment, a correction process is performed on a print head 1 that is configured to circulate the liquid, based on a prediction of the increase in sedimentation amount, the pigment concentration of the liquid, and the amount of ink consumed. The correction process is a process for correcting the amount of ink applied per unit area on the print medium by the print head 1. In addition to the correction process, it is also possible to perform control such as draining for maintenance or changing the circulation conditions, based on a prediction of the increase in sedimentation amount, the pigment concentration of the liquid, and the amount of ink consumed. Below, we will explain how to determine the value of the sedimentation increase, Yx, the value of the pigment concentration of the liquid, and In, and then explain the correction process based on these values.

[0042] 9 is a flowchart of the ink consumption prediction process, which is performed in accordance with the program stored in the control ROM 505. That is, this process determines the value of the ink consumption In described above. This process is performed by the MPU 502 while the printing apparatus is running. This process is also executed by the MPU 502 of the printing apparatus by loading the program stored in the control ROM 505 into the RAM 503. In order to estimate the pigment concentration of the ink in the print head 1, in addition to the aforementioned amount of pigment sedimentation, it is necessary to know how much ink has been consumed from the print head 1 within the predicted period since ink refilling. In this embodiment, as described above, ink is supplied to the print head 1 under pressure. When ink is consumed from within the print head 1, ink of normal concentration is supplied to the print head 1 in the amount consumed. Since the pigment concentration reduced by sedimentation is restored by replacing the ink, the amount of ink consumed during printing operations, print head recovery operations, etc. is derived.

[0043] In S901, the MPU 502 determines through the PPI 501 whether or not there is a recording command from the host computer 500. If it is determined that there is no recording command, the MPU 502 proceeds to S904. If it is determined that there is a recording command, the MPU 502 proceeds to S902.

[0044] In S902, the MPU 502 refers to the print usage amount obtained from the print data stored in the print buffer 521 described above, and obtains the amount of ink consumed during printing.

[0045] In S903, the MPU 502 performs processing to add to the ink consumption amount In and stores the result in the RAM 503. In S904, the MPU 502 determines whether there is a recovery command from the host computer 500. If it is determined that there is no recovery command, the MPU 502 returns the processing to S901. If it is determined that there is a recovery command, the MPU 502 proceeds to S905.

[0046] In step S905, the MPU 502 references the recovery usage amount stored in advance in the ROM 505, and in step S906 adds this to the ink consumption amount In. The result of the addition is also saved in the RAM 503. When step S906 ends, the process returns to step S901. In this way, by adding the ink consumption amount In every time a print command or recovery command is issued, the amount of ink in the circulation path can be managed.

[0047] 10 is a flowchart of the pigment concentration derivation process. That is, this process determines the pigment concentration Nx of the liquid described above. This process is performed by the MPU 502 in accordance with a program stored in the control ROM 505. This process is performed by the MPU 502 as part of the correction process described below.

[0048] In S1001, the MPU 502 reads the previously acquired pigment concentration Nx from the RAM 503. In S1002, the MPU 502 reads from the ROM 505 the sedimentation amount increase Yx that will occur from the elapsed time since the previous (last) pigment concentration derivation process was performed to the elapsed time until the current pigment concentration derivation process is performed, which is acquired by the sedimentation amount increase prediction process.

[0049] In S1003, the MPU 502 reads from the RAM 503 the ink consumption amount In predicted by the ink consumption amount prediction process described above.

[0050] In S1004, the MPU 502 calculates the pigment concentration (estimated concentration) N based on the previously read pigment concentration Nx, the sedimentation amount increase Yx, the ink consumption amount In, the total amount of ink J initially filled in the print head 1, and the initial value N of the pigment concentration. x+1As mentioned above, when ink is consumed from the recording head 1, ink of the normal density (initial value N of the pigment density) is supplied to the recording head 1 in the amount corresponding to the consumed amount. x+1 is derived using the following equation (1).

[0051] N x+1 =((J-In)×Nx+N×In-Yx)÷J...Equation (1) In S1005, the MPU 502 updates the current pigment concentration Nx and saves it in the RAM 503. In S1006, the MPU 502 resets the ink consumption amount In saved in the RAM 503. The MPU 502 then returns to S1001 in this flowchart. By appropriately updating the pigment concentration Nx in this way, the pigment concentration in the circulation path can be managed.

[0052] (Regarding correction of density reduction due to ink sedimentation) The pigment concentration that has decreased due to ink sedimentation can be derived for each printing operation or recovery operation using the pigment concentration derivation process described above. In this embodiment, correction processing is performed based on the derived pigment concentration value. The content of the correction processing described below, like the pigment concentration derivation process described above, is stored in the control ROM 505 and is executed by the MPU 502.

[0053] (correction processing) The correction process in this embodiment will be described in detail.

[0054] 11 is a flowchart showing the correction process in this embodiment. This process is performed continuously while the printing apparatus is running.

[0055] In S1101, the MPU 502 determines whether or not a recording command has been received from the host computer 500. If it is determined that a recording command has been received, the MPU 502 proceeds to S1102. If it is determined that a recording command has not been received, the MPU 502 returns to S1101.

[0056] In S1102, the MPU 502 performs a pigment concentration derivation process. That is, the pigment concentration Nx is obtained by the process described in FIG. 10. In S1103, the MPU 502 corrects the amount of ink to be applied during printing based on the obtained current pigment concentration Nx and the normal pigment concentration N (initial pigment concentration N) when no sedimentation has occurred. Specifically, the print data (multiple-value density data) input from the host computer 500 is multiplied by N / Nx as a correction value. As a result, the amount of ink applied per unit area on the print medium is increased by (N / Nx) times.

[0057] In S1104, the MPU 502 performs the printing operation with the corrected ejection amount. In S1105, the MPU 502 updates the ink consumption amount In based on the amount of ink consumed in S1104 using the ink consumption amount prediction process described in Fig. 9, and further updates the pigment concentration using the pigment concentration acquisition process described in Fig. 10, and then returns to S1101.

[0058] As described above, this embodiment improves the printing accuracy of a print head capable of circulating liquid. Specifically, the correction process manages the pigment concentration within the print head 1, and if the pigment concentration of the ink flowing through the circulation flow path within the print head decreases due to sedimentation, the pigment concentration is calculated and a correction is made to the printing amount. In other words, as sedimentation progresses and the pigment concentration of the circulated ink decreases, the printing amount is increased so that the amount of ink per unit area increases. This stabilizes the image density rendered on the print medium regardless of the time elapsed since the ink was filled, and prevents defects such as pale colors in the printed product even if the pigment concentration decreases due to sedimentation.

[0059] <Embodiment 2> The correction process in this embodiment will be described in detail. In the first embodiment, a method was described in which the printing amount was corrected based on the pigment concentration derived by the pigment concentration derivation process. However, since there is a limit to the printing amount, including the amount of moisture that a printing medium can accept, it is assumed that there is also a limit to the pigment concentration that can be corrected. Therefore, in this embodiment, after the pigment concentration is derived, if the derived pigment concentration is equal to or less than a predetermined threshold, a process is performed to increase the pigment concentration until it becomes possible to perform the printing operation. Details will be explained below using Figure 12.

[0060] 12 is a flowchart of the correction process in this embodiment. In S1201, the MPU 502 determines whether a print command has been received from the host computer 500. If it is determined that a print command has been received, the MPU 502 proceeds to S1202; if no print command has been received, the MPU 502 terminates the process of this flowchart. In S1202, the MPU 502 derives the current pigment concentration Nx through a pigment concentration derivation process.

[0061] In S1203, the MPU 502 compares the pigment concentration Nx calculated in S1202 with P. Here, P is a pigment concentration that is a threshold value at which the recorded product will not be visually judged to be defective even if it drops below the normal pigment concentration N. If the MPU 502 determines that Nx is equal to or less than the threshold value P, it proceeds to S1204. If the MPU 502 determines that Nx is greater than P, it proceeds to S1206.

[0062] In S1204, the MPU 502 causes the recovery processing device 9 to discharge a certain amount of ink from within the print head through recovery processing such as preliminary ejection and suction. When the pigment contained in the ink settles, the pigment concentration of the circulated ink becomes lower than the initial value. By discharging this ink with a lower pigment concentration, ink having the initial pigment concentration is replenished into the print head 1 from outside the head. This increases the pigment concentration of the ink within the head (approaching the initial value). This makes it possible to maintain the image density equivalent to the initial value without correcting the ejection amount. In S1205, the MPU 502 again obtains the pigment concentration based on the newly supplied ink, and returns to S1203. This loop is repeated until the pigment concentration Nx within the print head becomes greater than the pigment concentration threshold P (until S1203 returns Yes).

[0063] If it is determined that Nx is greater than P, the MPU 502 performs a normal printing operation in S1206, and after the printing operation is completed, updates the pigment concentration Nx in S1207, after which the process returns to S1201.

[0064] In this embodiment, a pigment concentration threshold P is set in advance so that the printed product will not be judged as defective even if the pigment concentration drops below the normal pigment concentration N. If the pigment concentration of the ink in the print head is equal to or lower than the threshold P, the recovery processing device 9 performs recovery processing such as preliminary ejection and suction before the printing operation to discharge the ink from the print head. This allows printing to be performed with ink having a pigment concentration higher than the threshold P during the printing operation, making it possible to obtain a good printed product.

[0065] <Embodiment 3> The correction process in this embodiment will be described below. The correction process performed in the second embodiment discharges the settled ink when the ink level is equal to or lower than the set threshold P, so that the printed product can be expected to be of uniform quality, but there is a concern that the amount of wasted ink may increase.

[0066] Therefore, in this embodiment, a threshold Q is set that is lower than the threshold P set in the second embodiment. Then, if the pigment concentration is greater than the threshold Q, the amount of ink ejected is corrected as in S1103 in the first embodiment. This is expected to produce a high-quality product and suppress the increase in waste ink. The correction process of this embodiment will be explained below using FIG. 13. Note that the process explained in the second embodiment will not be explained below.

[0067] FIG. 13 is a flowchart of the correction process in this embodiment.

[0068] In S1303, the MPU 502 compares the pigment concentration Nx derived by the pigment concentration derivation process with a preset threshold Q. Here, Q is assumed to be a value lower than the threshold P described in the second embodiment. If the MPU 502 determines in S1303 that Nx is greater than Q, the process proceeds to S1306. If the MPU 502 determines that Nx is equal to or less than the threshold Q, the process proceeds to S1304. In S1306, the MPU 502 corrects the amount of ink to be printed based on the derived current pigment concentration Nx and the value of the normal pigment concentration N when no settling occurs. In S1307, the MPU 502 performs printing using the corrected amount of ink to be printed.

[0069] In this manner, in this embodiment, a threshold Q is set that is lower than the threshold set in embodiment 2. As a result, if the pigment concentration of the ink in the print head 1 is equal to or lower than threshold Q, the recovery processing device 9 performs recovery processing such as preliminary ejection or suction before printing, as in embodiment 2, and discharges the ink from the print head. If the value exceeds pigment concentration threshold Q, the ink discharge amount to be printed is corrected for the pigment concentration Nx at that time, as in embodiment 1, before printing. Since the pigment concentration threshold Q can be set to a value that is smaller than the pigment concentration threshold P in embodiment 2 by the amount of discharge amount correction, the amount of ink discharged is smaller than in embodiment 2. This makes it possible to reduce the amount of waste ink discharged and obtain good results.

[0070] <Other embodiments> In the above-described embodiment, the pigment concentration is derived from the method shown in Figures 7 to 10, but in practice this is not limited to this. For example, a sensor that measures the pigment concentration may be provided in the recording head, and the correction process shown in embodiments 1 to 3 may be performed based on the measured pigment concentration. In the above embodiment, the coloring material contained in the ink is described as a pigment, but the coloring material may also be a dye. Even dyes may have difficulty dissolving in liquid, and in such cases, the present disclosure is effective.

[0071] The present disclosure can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0072] The present disclosure also includes the following configurations. (Configuration 1) a recording head having a circulation means for circulating ink containing a coloring material; an estimation means for estimating the concentration of coloring material in the ink circulating within the recording head based on the amount of ink consumed by the recording head and the amount of coloring material settling in the recording head over a predetermined period of time; a processing means for executing a predetermined process in accordance with the estimated concentration estimated by the estimating means; A recording device comprising: (Configuration 2) The recording apparatus according to configuration 1, wherein the predetermined process is a process for adjusting the amount of ink to be deposited on a unit area of ​​a recording medium during a recording operation, based on the estimated density estimated by the estimation means. (Configuration 3) 3. The recording apparatus according to configuration 2, wherein the processing means corrects the amount of ink to be applied to a unit area based on an initial value of the density of the coloring material in the ink and the estimated density. (Configuration 4) 2. The recording apparatus according to configuration 1, wherein the predetermined process is a process of discharging a predetermined amount of ink circulating in the recording head and refilling the recording head with the predetermined amount of ink. (Configuration 5) 5. The recording apparatus according to any one of configurations 1 to 4, wherein the predetermined period is a period from the last recording performed using the recording head until the estimation means estimates the estimated density. (Configuration 6) 5. The recording apparatus according to configuration 4, wherein the processing means discharges a fixed amount of ink from the recording head when the estimated density is equal to or less than a first threshold value. (Configuration 7) The recording device described in configuration 1 is characterized in that, when the estimated density is greater than a second threshold value, the processing means adjusts the amount of ink to be deposited on a unit area of ​​the recording medium during the recording operation based on the estimated density estimated by the estimation means, and when the estimated density is equal to or less than the second threshold value, the processing means discharges a predetermined amount of ink circulating within the recording head and replenishes the predetermined amount of ink to the recording head. (Configuration 8) 8. The recording apparatus according to any one of configurations 1 to 7, wherein the ink is a pigment ink. (Configuration 9) 9. The recording apparatus according to any one of configurations 1 to 8, wherein the ink contains a white coloring material. (Configuration 10) A method for controlling a recording device having a recording head with a circulation unit for circulating ink containing a coloring material, comprising: an estimation step of estimating a concentration of coloring material in ink circulating within the print head based on an amount of ink consumed by the print head and an amount of coloring material settling in the print head over a predetermined period of time; a processing step of executing a predetermined process in accordance with the estimated concentration estimated in the estimating step; 10. A method for controlling a recording apparatus, comprising:

Claims

1. a recording head having a circulation means for circulating ink containing a coloring material; an estimation means for estimating the concentration of coloring material in the ink circulating within the recording head based on the amount of ink consumed by the recording head and the amount of coloring material settling in the recording head over a predetermined period of time; a processing means for executing a predetermined process in accordance with the estimated concentration estimated by the estimating means; A recording device comprising:

2. 2. The printing apparatus according to claim 1, wherein the predetermined process is a process for adjusting the amount of ink applied to a unit area of ​​a printing medium during a printing operation, based on the estimated density estimated by the estimating means.

3. 3. The printing apparatus according to claim 2, wherein said processing means corrects the amount of ink to be applied to a unit area based on an initial value of the density of the coloring material in said ink and said estimated density.

4. 2. The printing apparatus according to claim 1, wherein the predetermined process is a process of discharging a predetermined amount of ink circulating in the print head and refilling the print head with the predetermined amount of ink.

5. 2. The recording apparatus according to claim 1, wherein the predetermined period is a period from the last recording performed using the recording head until the estimation means estimates the estimated density.

6. 5. The printing apparatus according to claim 4, wherein the processing means discharges a fixed amount of ink from the print head when the estimated density is equal to or less than a first threshold value.

7. The recording device described in claim 1, characterized in that when the estimated density is greater than a second threshold value, the processing means adjusts the amount of ink to be deposited on a unit area of ​​the recording medium during the recording operation based on the estimated density estimated by the estimation means, and when the estimated density is less than or equal to the second threshold value, the processing means discharges a predetermined amount of ink circulating within the recording head and replenishes the predetermined amount of ink to the recording head.

8. 2. The recording apparatus according to claim 1, wherein the ink is a pigment ink.

9. 2. The recording apparatus according to claim 1, wherein the ink contains a white coloring material.

10. A method for controlling a recording device having a recording head with a circulation unit for circulating ink containing a coloring material, comprising: an estimation step of estimating a concentration of coloring material in ink circulating within the print head based on an amount of ink consumed by the print head and an amount of coloring material settling in the print head over a predetermined period of time; a processing step of executing a predetermined process in accordance with the estimated concentration estimated in the estimating step; 10. A method for controlling a recording apparatus, comprising:

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