Inkjet recording device and its control method

Abstract

Traditionally, parameters dependent on the material of the recording head were used to determine whether or not the head was failing to release data. However, because there are variations in material thickness and dimensions for each recording head, it is difficult to calculate highly accurate predictive values. [Solution] An inkjet recording apparatus comprising a recording head having a plurality of ejection ports for ejecting ink, a temperature detection means for detecting the temperature of the recording head, and a recovery means for performing a recovery operation of the recording head, wherein a first temperature rise amount associated with the ejection operation of the recording head is obtained at a first timing, and a second temperature rise amount associated with the ejection operation of the recording head is obtained at a second timing different from the first timing. Then, if the second temperature rise amount is greater than or equal to a predetermined value than the first temperature rise amount, the recovery operation of the recording head is performed.

Description

Technical Field

[0001] The present invention relates to an inkjet recording apparatus and a control method thereof.

Background Art

[0002] In a recording head of an inkjet recording apparatus, air bubbles may remain in an ink flow path or an ink liquid chamber. Examples of the cause of such a situation include the following cases. ·Small air bubbles existing in the flow path accumulate while ink is not ejected for a long period (leaving bubbles). ·Ink whose temperature has decreased during the non-ejection period is heated by a heater at the time of ejection, so that dissolved gas precipitates (printing bubbles).

[0003] When the air bubbles remaining in this manner spread throughout the entire recording head, ink cannot be supplied over most of the ejection ports, resulting in a non-ejection state (continuous non-ejection across a wide range). When such continuous non-ejection across a wide range occurs, most of the recorded image becomes white voids, causing image degradation. In order to prevent such image degradation, suction recovery control is performed on the air bubbles inside the flow path in inkjet recording apparatuses.

[0004] In performing such suction recovery, it is necessary to detect the air bubbles that cause continuous non-ejection across a wide range in the flow path of the recording head. As a method for detecting air bubbles in the flow path, there is a method of measuring the temperature in the vicinity of the ejection ports of the recording head. In general, heat is less likely to dissipate in air. Therefore, when the operation of ejecting ink is repeated in a state where residual air bubbles are present, the heater heated by the ejection operation is less likely to dissipate heat, and the amount of temperature rise in the vicinity of the ejection ports increases. On the other hand, when no residual air bubbles are present, the ink foams due to heating by the heater and is ejected, then the foam disappears and the ink comes into contact with the heater. As a result, the heat dissipation rate of the heater increases, and the amount of temperature rise in the vicinity of the ejection ports decreases. That is, by detecting the temperature rise change of the heater during the ink ejection operation, it is possible to detect the presence or absence of residual air bubbles that cause continuous non-ejection across a wide range.

[0005] Patent Document 1 first predicts the temperature change associated with recording when ink is ejected normally using a heat transfer equation (calculation of predicted value). Then, it measures the temperature near the ejection port at predetermined time intervals (calculation of measured value), and based on the difference between the measured value and the predicted value, it determines whether or not ink is not being ejected properly. Based on this determination, it stops the recording operation or performs a suction recovery operation of the recording head. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-237675 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Patent Document 1 detects whether a fluffy ink discharge state due to residual bubbles is occurring based on differences in the amount of temperature change associated with recording. The detection of this fluffy ink discharge state uses a predicted value based on a heat transfer equation. This predicted value calculation uses parameters that depend on the material of the recording head. Since the recording head is composed of multiple materials, accurately calculating the amount of temperature change contributed by each material is necessary to improve the accuracy of the predicted value. However, because there are variations in material thickness and dimensions for each recording head, calculating a highly accurate predicted value is difficult. If the accuracy of the predicted value drops drastically, excessive detection of the fluffy ink discharge state can lead to excessive suction recovery operations, resulting in increased waste ink volume and increased downtime.

[0008] The object of the present invention is to solve at least one of the problems of the prior art described above.

[0009] The objective of the present invention is to solve the above problem by determining whether or not to perform a recovery operation of the recording head using a method that does not rely on predicted values ​​from theoretical formulas. [Means for solving the problem]

[0010] To achieve the above objective, an inkjet recording apparatus according to one aspect of the present invention has the following configuration. That is, An inkjet recording apparatus comprising a recording head having a plurality of ejection ports for ejecting ink, a temperature detection means for detecting the temperature of the recording head, and a recovery means for performing a recovery operation of the recording head, At the first timing, a first acquisition means acquires the first temperature rise amount associated with the ejection operation of the recording head using the temperature detection means, A second acquisition means acquires, by the temperature detection means, a second temperature rise amount associated with the ejection operation of the recording head at a second timing different from the first timing, The system is characterized by having a control means that controls the recovery means to perform a recovery operation of the recording head when the second temperature rise is greater than or equal to a predetermined value than the first temperature rise. [Effects of the Invention]

[0011] According to the present invention, it is possible to accurately determine when a recovery operation of the recording head is necessary. This has the effect of reducing waste ink volume and downtime by avoiding unnecessary recovery operations of the recording head.

[0012] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. [Brief explanation of the drawing]

[0013] The attached drawings are included in the specification and constitute part thereof, illustrating embodiments of the present invention and are used together with the description to explain the principles of the present invention. [Figure 1] A schematic diagram showing an example of the configuration of an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] A diagram illustrating the structure of a recording head according to an embodiment. [Figure 3] A block diagram illustrating the configuration for controlling the inkjet recording device according to this embodiment. [Figure 4] A flowchart for explaining non-ejection detection and recovery processing in the inkjet recording apparatus according to Embodiment 1. [Figure 5] Graph (a) showing an example of the temperature rise amount of the recording head 10 with respect to the number of preliminary ejections, and graph (b) showing the temperature rise amount when a suction recovery operation is performed. [Figure 6A] A flowchart for explaining non-ejection detection and recovery processing in the inkjet recording apparatus according to Embodiment 2. [Figure 6B] A flowchart for explaining the processing of S622 and S624 in FIG. 6A. [Figure 7] A graph showing measurement results of the temperature rise amount according to Embodiments 2 and 3. [Figure 8A] A flowchart for explaining non-ejection detection and recovery processing in the inkjet recording apparatus according to Embodiment 3. [Figure 8B] A flowchart for explaining the processing of S821 and S834 in FIG. 8A. [Figure 9] A diagram showing an example of determining a mode for determining whether to execute a suction recovery operation based on the number of recording dots and capping time according to Embodiment 2. [Mode for Carrying Out the Invention]

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. A plurality of features are described in the embodiments, not all of the plurality of features are necessarily essential to the invention, and the plurality of features may be arbitrarily combined. Furthermore, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0015] First, terms used in the present embodiment are defined in advance as follows. · "Recording" In this specification, "record" does not refer only to cases where meaningful information is formed, such as characters or figures. It does not refer to cases where the information is meaningful or meaningless, or where it is manifested in a way that can be perceived visually by a human being. It also broadly refers to cases where images, patterns, etc. are formed on a recording medium, or where a medium is processed. • "Recording medium" The term "recording medium" refers not only to paper, which is commonly used in recording devices, but also to a wider range of materials capable of accepting ink, such as cloth, plastic film, metal plates, glass, ceramics, wood, and leather. ·"ink" Ink, as with the definition of "record" above, should be interpreted broadly and refers to a medium containing recording material that, when applied to a recording medium, can be used to form images, patterns, designs, etc., or to process the recording medium, or to treat the ink. Physically, it is a liquid. The ink treatment mentioned above refers, for example, to the coagulation or insolubilization of the colorant in the ink applied to the recording medium. ·"nozzle" Unless otherwise specified, the term "nozzle" refers to the discharge port. Inside the nozzle are interconnected liquid channels and an element that generates energy used for ink ejection. ·"scanning" To record data onto a recording medium, the recording head scans the recording medium and performs the recording. Here, scanning refers to the movement of the head during acceleration and deceleration for the purpose of recording or related to recording. • "Round-trip record" "Round-trip recording" refers to recording while performing the above-mentioned "recording" or "scanning" motion back and forth on the paper. Round-trip scanning, round-trip recording, bidirectional scanning, and bidirectional recording all refer to the same thing.

[0016] Figure 1 is a schematic diagram showing an example of the configuration of an inkjet recording apparatus 100 according to an embodiment of the present invention.

[0017] This inkjet recording device 100 includes a drive motor 101, a drive belt 102 connected to the drive motor 101, and a recording head 10 transported by the drive belt 102. The recording head 10 is capable of reciprocating scanning along the ±X axis direction (main scanning direction) by the rotation of the drive motor 101, and its movement can be controlled to any location within the transport area. The inkjet recording device 100 also transports a sheet-shaped recording medium S in the +Y axis direction (sub-scanning direction) via a paper feeding mechanism (not shown). Recording is performed by ejecting ink toward the recording medium S while moving the recording head 10 back and forth in the main scanning direction. Once one scan is completed, the paper feeding mechanism transports the recording medium S in the +Y direction. The area within the transport area where the recording head 10 can eject ink toward the recording medium S is called the recording area.

[0018] Outside this recording area is a recovery unit 200 for recovering from ink ejection problems in the recording head 10. The recording head 10 remains stationary in this position when no recording operation is being performed. The recovery unit 200 is equipped with a cap 201 that caps the ink ejection surface of the recording head 10. A suction pump 202 is connected inside the cap 201. By driving the suction pump 202 with the cap 201 capping the ink ejection port of the recording head 10, a negative pressure can be introduced inside the cap 201. This negative pressure introduction allows ink to be sucked and discharged from the ink ejection port of the recording head 10 into the cap 201 (suction recovery). This suction recovery operation recovers from ink ejection problems in the recording head 10 and maintains ink ejection performance. In addition, the recording head 10 can also eject ink toward the cap 201 in the recovery unit 200 (preliminary ejection). Furthermore, even if the suction recovery operation is not performed during capping, capping with cap 201 has a certain effect in maintaining ink ejection performance by suppressing the evaporation of solvent from the ejection port.

[0019] Figure 2 illustrates the structure of the recording head 10 according to the embodiment. Figure 2(a) is a plan view of the nozzle portion provided on the recording head 10. Figure 2(b) is an enlarged cross-sectional view taken from the Y-axis perspective, cut along the dotted line AA shown in Figure 2(a). Figure 2(c) is an enlarged cross-sectional view showing the membrane structure near the discharge port in Figure 2(b).

[0020] As shown in Figure 2(a), the recording head 10 has multiple ejection ports 11 arranged in a row in the sub-scanning direction (Y direction). The structure of the ejection section around the ejection ports 11 will be explained using Figure 2(b). The substrate 12 (Si substrate) that constitutes the ejection section is equipped with a common liquid chamber 13 that communicates with the ink storage tank section, and a liquid supply port 14 that supplies ink from the common liquid chamber 13 to the ejection ports 11. The common liquid chamber 13 and the liquid supply port 14 extend along the entire length of the row of ejection ports arranged in the sub-scanning direction. In addition, an ejection port plate 16 with a flow path wall is bonded to the substrate 12 to form a liquid supply flow path 15 that connects the liquid supply port 14 and the ejection ports 11. Furthermore, a heater 17 (electric heat conversion element) for ejecting ink is provided on the substrate 12 at a position opposite the ejection ports 11. When the heater 17 is energized for a short time, the nearby liquid (ink) is rapidly heated and foamed, and the ink passes through the ejection ports 11 and is ejected. Furthermore, a temperature sensor 18 (temperature sensing element) for detecting temperature changes is formed near the heater 17 on the substrate 12. In Figure 2(b), the temperature sensor 18 is placed directly above the heater 17, but since the purpose is to detect temperature changes near the heater 17, it may also be placed, for example, directly below or to the side of the heater 17.

[0021] Next, with reference to Figure 2(c), the structures of the heater 17 and temperature sensor 18 formed on the substrate 12 will be described. Both the heater 17 and the temperature sensor 18 are formed by laminating them on the substrate 12 using the same film deposition process. On the substrate 12, individual wiring 20 made of Al or the like for connecting to the temperature sensor 18 and Al wiring for connecting the heater 17 and the control circuit formed on the substrate 12 are formed via a heat storage layer 19 made of a thermal oxide film SiO2 or the like. The temperature sensor 18 has a thin film resistor whose resistance value changes according to the temperature. Examples of materials for this thin film resistor include Al, Pt, Ti, Ta, and Cr. Furthermore, on the substrate 12, the heater 17, a passivation layer 22 made of SiN or the like, and a cavitation-resistant film 23 made of a Ta film are formed by densely laminating them via an interlayer insulating film 21 using a semiconductor process.

[0022] Figure 3 is a block diagram illustrating the control configuration of the inkjet recording apparatus 100 according to this embodiment. In Figure 3, parts common to Figures 1 and 2 are indicated by the same reference numerals.

[0023] In the inkjet recording device 100, the image input unit 303, the corresponding image signal processing unit 304, the operation unit 305, and the CPU 300 that controls the inkjet recording device 100 are all configured to access the main bus 306. The CPU 300 has a ROM 301 and a RAM 302, and by executing a program stored in the ROM 301, it provides appropriate recording conditions to the input information and performs control to drive the recording head 10 for recording. The ROM 301 also stores a program in advance to maintain the recovery operation and ejection performance of the recording head 10, and by executing this program, the CPU 300 provides recovery conditions such as pre-ejection to the recovery processing control circuit 307, the recording head 10, etc., as needed. When the CPU 300 executes the program, it temporarily stores various data in the RAM 302 for use in control.

[0024] The recovery motor 308 can independently drive the cleaning blade 309, cap 201, and suction pump 202, which are positioned opposite the recording head 10. In particular, when the recovery motor 308 only performs capping of the discharge surface by the cap 201, the capping timer 313 can measure the capping time of the recording head 10. The time thus measured can be stored in the RAM 302 on the CPU 300 or the like.

[0025] The recording head drive control circuit 310 drives the heater 17 of the recording head 10 according to the driving conditions given by the CPU 300, causing the recording head 10 to perform preliminary ink ejection and ink ejection for recording. A temperature sensor 18 is also located on the recording head 10, and the CPU 300 can obtain the temperature inside the recording head 10 by issuing a temperature acquisition command at a predetermined timing. The temperature information thus obtained is stored in the RAM 302 and used for various controls.

[0026] Furthermore, during recording to the recording medium S, the number of times the heater 17 is driven, i.e., the number of ink droplets (recording dots) ejected from the ink nozzle, can be measured. This number of recording dots is counted using the dot counter 311, and the counted value is stored in the RAM 302 on the CPU 300. The temperature acquisition timer 312 is a timer that determines the timing for transitioning to the execution of the suction recovery operation and various conditions. For example, it is set to start timing after the initial ink filling or after suction recovery by the suction pump 202 has been performed.

[0027] Based on the components described above, Embodiment 1 of the present invention will be described below.

[0028] [Embodiment 1] Figure 4 is a flowchart illustrating the non-discharge detection and recovery process in the inkjet recording device 100 according to Embodiment 1. Figure 4(a) shows the process of measuring a reference temperature rise (ΔT1), and Figure 4(b) shows the process of determining whether to perform an suction recovery operation and then performing the recovery operation. Figure 4(c) shows the process of measuring the temperature rise (ΔT2) to be determined, which is process S411 in Figure 4(b). Each step will be explained in detail below. Note that the processes shown in these flowcharts are realized by the CPU 300 executing a program stored in the ROM 301.

[0029] First, we will explain the process for obtaining the reference temperature rise (ΔT1) shown in Figure 4(a). This process is performed, for example, immediately after the ink is filled into the recording head 10, or immediately after the suction recovery operation.

[0030] First, in S401, the CPU 300 measures the temperature of the recording head 10, which has not performed any ejection operations and has become accustomed to the surrounding environment, using the temperature sensor 18. The temperature information acquired at this time is stored in the variable (T1) of RAM 302. Next, in S402, the CPU 300 reads the number of pre-ejections, which is the number of pre-ejections pre-stored in ROM 301, and stores it in the variable (X) of RAM 302. At the same time, it provides the read conditions to the recording head drive control circuit 310 to execute pre-ejection. In Embodiment 1, the number of pre-ejections X is set to "500". Also, in this process, the variable (A) of RAM 302, which stores the cumulative value A of the number of pre-ejections ejected, is initialized to 0, and the variable (i) of RAM 302, which stores the number of measurements, is initialized to 1. Then, in S403, the CPU 300 executes pre-ejection of the recording head 10 based on the ejection conditions read in S402. Here, 500 pre-ejections are executed. Next, in S404, the CPU 300 obtains the temperature of the recording head 10 after the pre-discharge is performed using the temperature sensor 18 and stores it in the variable (Ti1) of RAM 302. Next, in S405, the CPU 300 obtains the difference between the temperatures obtained in S401 and S404 (here, (Ti1-T1)) to obtain the amount of temperature rise (ΔTi1) caused by the 500 pre-discharges. Then, in S406, the CPU 300 updates the stored cumulative value A of the number of pre-discharges. Specifically, it adds the number of pre-discharges X to the stored variable (A) (A=A+X) and also increments the variable (i) by 1. Then, in S407, the CPU 300 determines whether the cumulative value A of the number of pre-discharges in variable (A) has reached a predetermined number (here, for example, 5000). If the cumulative value A is not 5000 or more, the CPU 300 proceeds to S403, performs pre-discharge again, and measures the amount of temperature rise. In this way, if the cumulative value A exceeds a predetermined number in S407, this process is terminated. Alternatively, in S407, the termination of this process may be determined based on whether the variable (i) in RAM302, which stores the number of measurements, has become "11". Furthermore, the determination of whether to terminate the process based on the number of measurements may also be used in the following S427, S607, S616, S637, S646, S807, S816, S836, and S846.

[0031] This process allows us to obtain the temperature rise amount for each predetermined number of pre-discharged shots, which changes until the cumulative value of the pre-discharged shots reaches a predetermined value (reference temperature rise amount).

[0032] Figure 5(a) is a graph showing an example of the temperature rise of the recording head 10 in relation to the number of pre-discharged shots. Here, the horizontal axis shows the number of pre-discharged shots, and the vertical axis shows the temperature rise. The solid line in the figure shows an example of the temperature rise (ΔTi1: i=1~10) measured when the number of pre-discharged shots is set to 500 and the cumulative number of shots reaches 5000. This relationship between the number of pre-discharged shots and the temperature rise is stored in the RAM 302 by the CPU 300. Note that the interval between pre-discharged shots for temperature measurement and the cumulative number of shots that constitute the measurement range can be changed as needed.

[0033] Next, referring to the flowchart in Figure 4(b), we will explain the process for determining whether or not to perform a recovery operation on the recording head 10.

[0034] As criteria for deciding whether to proceed to the execution determination process for the suction recovery operation, for example, the elapsed time since the measurement of the reference temperature rise amount, as explained in the flowchart of Figure 4(a), and the number of recorded dots discharged since the measurement of the reference temperature rise amount can be used. The elapsed time since the measurement of the reference temperature rise amount can be obtained by the temperature acquisition timer 312. The number of recorded dots since the measurement of the reference temperature rise amount can be obtained from the count value of the dot counter 311. When either the elapsed time or the number of recorded dots exceeds a certain threshold, the system proceeds to the determination process for whether to execute the recovery operation. In Embodiment 1, the number of recorded dots is used to determine whether to execute the recovery operation.

[0035] In S410, the CPU 300 compares the number of recorded dots (Ctotal), measured using the dot counter 311 during recording, with a threshold (Cth) pre-stored in the CPU 300's ROM 301. If the number of recorded dots (Ctotal) exceeds the threshold (Cth), the process proceeds to S411 to determine whether to perform a recovery operation; otherwise, the recording head recovery process is not performed. The variable (Ctotal) that stores the number of recorded dots measured using the dot counter 311 is located in RAM 302.

[0036] Figure 4(c) is a flowchart illustrating the process of measuring the temperature rise amount (ΔT2) of the target for determination in S411 of the flowchart in Figure 4(b). This process is performed in S411 when it is necessary to determine whether or not to perform a recovery operation in S410 of Figure 4(b).

[0037] First, in S420, the CPU 300 acquires the temperature rise (T1) associated with pre-discharge and adjusts the temperature of the recording head 10 to the acquired temperature. This temperature adjustment of the recording head 10 is performed using the heater 17 and temperature sensor 18, based on the temperature of the recording head 10 that has become accustomed to the surrounding environment, which is stored in RAM 302 in S401. Next, in S421, the CPU 300 reads the number of pre-discharge shots X that has been stored in ROM 301 in the same way as in S402. Here, the number of pre-discharge shots X is "500". The variable (A) in RAM 302 that stores the cumulative value A of the number of pre-discharge shots that have been discharged is initialized to 0, and the variable (i) in RAM 302 that stores the number of measurements is initialized to 1. Next, in S423, the CPU 300 provides the read conditions to the recording head drive control circuit 310 in the same way as in S403, and performs pre-discharge of the recording head 10. In Embodiment 1, the number of pre-discharge shots X is set to 500.

[0038] Next, in S424, the CPU 300 obtains the temperature (Ti2) of the recording head 10 after the pre-discharge is performed using the temperature sensor 18. Next, in S425, the CPU 300 performs a calculation to obtain the temperature rise due to pre-discharge (ΔTi2=Ti2-T1) by taking the difference between the temperatures obtained in S420 and S424. Next, in S426, the CPU 300 updates the stored cumulative value A of the number of pre-discharges. Specifically, it adds the set number of pre-discharges to the stored cumulative value A (A=A+X) and also increments the variable (i) by 1. Then, in S427, the CPU 300 determines whether the cumulative value A of the number of pre-discharges has reached a predetermined value (5000 in this case). If it is not 5000 or more, it proceeds to S423, where it performs pre-discharge again and measures the temperature rise in S424. When it is determined in S427 that the cumulative value of the number of pre-discharges has reached a predetermined value, this process is terminated. The relationship between the number of pre-discharged shots and the temperature rise obtained here is stored in RAM302, etc.

[0039] Through the processes described so far, we have obtained two temperature rise values: the reference temperature rise (ΔT1) measured in S401-S407, and the temperature rise (ΔT2) (the temperature rise subject to judgment) measured in S420-S427.

[0040] Returning to Figure 4(b), once the processing in S411 is complete, the process proceeds to S412, where the CPU 300 compares the reference temperature rise (ΔTi1) measured up to this point with the temperature rise of the target for judgment (ΔTi2). Here, the temperature is compared for each of i=1 to 10. That is, in this process, the CPU 300 performs a difference calculation (ΔTi2-ΔTi1) for each of i=1 to 10. It then determines whether the difference is greater than or equal to a predetermined threshold (Tth) stored in the ROM 301. If it is greater than or equal to the threshold, the process proceeds to S413 to execute the suction recovery operation of the recording head 10. On the other hand, if the difference is less than the predetermined threshold (Tth), the process ends without performing the suction recovery in S413.

[0041] In other words, if the temperature rise amount to be judged (ΔT2) is higher than the reference temperature rise amount (ΔT1) by a predetermined threshold (Tth), it is considered that the heat dissipation rate of the heater has decreased due to residual air bubbles in the discharge port. Therefore, in such cases, the recording head 10 is subjected to a suction recovery operation to remove the residual air bubbles and prevent the recording head from becoming stuck.

[0042] In Embodiment 1, a predetermined threshold Tth is set to 6°C, and the suction recovery operation is performed when the temperature rise of the target to be judged is 6°C or higher than the reference temperature rise. The suction recovery operation performed in S413 is carried out by driving the recovery motor 308 via the recovery processing control circuit 307.

[0043] Figure 5(c) is a graph showing the temperature rise when the suction recovery operation is performed. The horizontal axis represents the number of pre-discharge shots, and the vertical axis represents the temperature rise. The solid line in the figure represents the reference temperature rise (ΔT1) measured in S401 to S407, and the dotted line represents the threshold temperature rise (a temperature 6°C higher than the reference temperature rise plotted). Furthermore, the dashed line represents the temperature rise of the target for judgment measured in S420 to S427. In Figure 5(c), the temperature rise of the target for judgment (ΔT2) is higher than the threshold temperature rise, so in this case, the suction recovery operation is required. Here, the suction recovery operation is performed when the temperature rise of the target for judgment becomes higher than the threshold. However, the present invention is not limited to this, and the suction recovery operation may also be designed to have multiple suction intensities, and the suction intensity may be changed according to the difference from the threshold.

[0044] On the other hand, Figure 5(b) is a graph showing the temperature rise when the suction recovery operation is not performed. The notation in the figure is the same as in Figure 5(c). As shown in the figure, the temperature rise amount (ΔT2) for which the judgment is made, shown by the dashed line, is lower than the threshold temperature rise amount shown by the dotted line, so in this case the suction recovery operation is unnecessary.

[0045] As explained above, Embodiment 1 utilizes temperature rise measured at two different timings to determine whether or not to perform a recording head recovery operation. Specifically, in Embodiment 1, when determining whether or not to perform a recording head recovery operation, the temperature rise of the target of the determination is not compared with a predicted value based on a theoretical formula, but rather with a reference temperature rise based on actual measurements. This makes it possible to detect a blistering condition without being affected by variations in materials, etc., that exist for each recording head, and has the effect of performing a recording head recovery operation at a more appropriate timing.

[0046] [Embodiment 2] In Embodiment 1 described above, a reference temperature rise was determined at a first timing, and a determination was made whether or not to perform a recording head recovery process by comparing this with the target temperature rise acquired at a second timing. In contrast, Embodiment 2 will be described in the case where the reference temperature rise is acquired multiple times. Note that the configuration of the inkjet recording device in Embodiment 2 is the same as in Embodiment 1 described above, so its explanation will be omitted.

[0047] Figure 6A is a flowchart illustrating the non-discharge detection and recovery process in the inkjet recording device 100 according to Embodiment 2. Figures 6A(a) and (b) are flowcharts illustrating the process of measuring multiple reference temperature rise amounts, and Figure 6A(c) is a flowchart illustrating the process of determining whether to perform an suction recovery operation and executing the recovery process. Furthermore, Figure 6B(a) is a flowchart illustrating the acquisition process of ΔT2n in S622 of Figure 6A(c), and Figure 6B(b) is a flowchart illustrating the acquisition process of ΔT2h in S624 of Figure 6A(c). Note that the processes shown in these flowcharts are realized by the CPU 300 executing a program stored in the ROM 301.

[0048] First, we will explain the process of measuring multiple reference temperature rise amounts, as shown in Figures 6A(a) and 6A(b). This process is performed immediately after the ink is filled into the recording head 10, or immediately after the suction recovery operation, similar to Embodiment 1. However, in Embodiment 2, the reference temperature rise amount is acquired multiple times. That is, after performing the process in Figure 6A(a), the process in Figure 6A(b) is performed while the recording head is still accumulating heat. For S601 to S607 in Figure 6A(a), the same process as S401 to S407 described in Embodiment 1 is performed. This is taken as the reference temperature rise amount under normal conditions. After acquiring the reference temperature rise amount under normal conditions, the processes in S610 to S616 in Figure 6A(b) are performed.

[0049] The process in Figure 6A(a) is basically the same as the process in Figure 4(a), so its explanation will be omitted. Here, the temperature rise amount is obtained for every predetermined number of pre-discharged shots (500 in this case) until the cumulative value A of the number of pre-discharged shots reaches a predetermined value (5000) (reference temperature rise amount). Here, the reference temperature rise amount at this time is defined as ΔT1n.

[0050] The process in Figure 6A(b) is basically the same as the process in Figure 4(b), and the temperature rise amount is obtained for every predetermined number of pre-discharged shots (500 in this case) until the cumulative value A of the number of pre-discharged shots reaches a predetermined value (5000) (the reference temperature rise amount in the heat storage state). Here, the reference temperature rise amount in the heat storage state at this time is denoted as ΔT1h. The explanation of this process is almost the same as that of Figures 4(a) and 4(c) above, so it will be briefly explained below.

[0051] In Figure 6A(b), first, in S610, the CPU 300 uses the heater 17 to regulate the temperature of the recording head 10 to a certain temperature (T1h). In Embodiment 2, as an example, the temperature (T1h) at this time is set to 50°C. The set temperature at this time only needs to be higher than the ambient temperature, and this temperature value is stored in the ROM 301 or the like. Then, in S611 to S616, the CPU 300 acquires the temperature rise amount (ΔT1h) of the recording head 10 for each number of pre-discharged discs, similar to S403 to S407 in Figure 4 described above. Then, in S616, the CPU 300 determines that the cumulative value A has reached a predetermined value (5000 in this case) or more and terminates this process.

[0052] This process allows us to obtain the temperature rise of the recording head 10 for each predetermined number of pre-discharges, which changes until the cumulative number of pre-discharges reaches a predetermined value. The temperature rise of the recording head 10 obtained through this process (ΔT1h) is used as the reference temperature rise in the heat storage state.

[0053] Figure 7(a) is a graph showing the reference temperature rise (ΔT1n) of the recording head under normal conditions according to Embodiment 2. This is the same as in Figure 5(a). Figure 7(b) is a graph showing the reference temperature rise (ΔT1h) of the recording head under heat storage conditions according to Embodiment 2. In Figures 7(a) and (b), the horizontal axis represents the number of pre-discharged shots, and the vertical axis represents the temperature rise. The measurement results are shown when the temperature rise was measured up to 5000 shots, with pre-discharge intervals of 500 shots. In the heat storage condition shown in Figure 7(b), it can be seen that the temperature rise of the recording head is smaller in proportion to the number of pre-discharged shots.

[0054] Figures 7(c) and 7(d), similar to Figures 5(b) and 5(c), show the measurement results when measuring the temperature rise up to 5000 shots when the recording head is in a normal state and not in a heat-accumulating state. As in Figure 5, the dotted line indicates the threshold temperature rise, and the dashed line indicates the measured temperature rise of the target for judgment.

[0055] Figures 7(e) and 7(f) show the measurement results when measuring the temperature rise up to 5000 shots while the recording head is in a heat storage state. Here again, the horizontal axis represents the number of pre-discharged shots, and the vertical axis represents the temperature rise. The solid line shows the reference temperature rise, and the dashed line shows the temperature rise measured in the heat storage state. The dotted line shows the threshold used to determine whether or not to perform the suction recovery operation. The relationship between the number of pre-discharged shots and the temperature rise is stored on the CPU 300. The interval between pre-discharged shots for temperature measurement and the total number of shots in the measurement range can be arbitrarily changed. In addition, multiple reference temperature rise values ​​in the heat storage state can be acquired.

[0056] Next, with reference to Figure 6A(c), the process of determining whether to perform a suction recovery operation and executing the recovery process according to Embodiment 2 will be described. In Embodiment 2, the determination to proceed to the determination of whether to perform a suction recovery operation is made using, for example, the number of recorded dots ejected after measuring the reference temperature rise and the cumulative capping time after measuring the reference temperature rise. The number of recorded dots is calculated using the dot counter 311. The capping time after measuring the reference temperature rise is calculated using the capping timer 313.

[0057] In S620, the CPU 300 first performs a determination based on the number of recorded dots. Specifically, it compares the number of recorded dots (Ctotal) measured using the dot counter 311 during the recording operation with a threshold (Cth) pre-stored in the ROM 301. If the number of recorded dots (Ctotal) does not exceed the threshold (Cth), the process proceeds to S622, where the CPU 300 moves on to measuring and determining the temperature rise in the normal state. On the other hand, if the number of recorded dots (Ctotal) exceeds the threshold (Cth), the process proceeds to S621, where the CPU 300 performs a determination based on the cumulative capping time (elapsed time) since the measurement of the reference temperature rise. In S621, after measuring the reference temperature rise, the CPU 300 compares the capping time (t) measured by the capping timer 313 with a predetermined time stored in the ROM 301, in this case a threshold (t0). If the capping time (t) exceeds the threshold (t0), the process proceeds to S622 to execute the normal state determination process. On the other hand, if it is determined that the predetermined time has not been exceeded, the process proceeds to S624, where the measurement and determination of the temperature rise in the heat storage state takes place. The conditions for the determination in S620 and S621 are summarized in Figure 9. Figure 9 shows an example of determining a mode for deciding whether to perform a suction recovery operation based on the number of recorded dots and the capping time according to Embodiment 2.

[0058] According to this, if the number of recorded dots is above a threshold and the capping time is below a threshold (t0), it is determined that the recording head 10 is in a heat storage state, and the temperature rise in the heat storage state is measured and judged. Otherwise, the temperature rise in the normal state is measured and judged.

[0059] Figure 6B(a) is a flowchart illustrating the measurement process for the temperature rise (ΔT2n) of the recording head under normal conditions in S622 of Figure 6A(c).

[0060] First, in S630, the CPU 300 adjusts the temperature of the recording head 10 to the temperature (T1n) measured in S601 in Figure 6A(a). This temperature adjustment of the recording head is performed using the heater 17 and temperature sensor 18 based on the measured temperature information stored in RAM 302 in S601. Next, in S631, the CPU 300 reads the number of pre-discharge shots X stored in ROM 301 and stores it in the variable (X) in RAM 302. It also initializes the variable (A) in RAM 302, which counts the cumulative value A, to 0, and sets the variable (i), which stores the number of measurements, to 1. Then, in S632, the CPU 300 provides the pre-discharge conditions read in S631 to the recording head drive control circuit 310 and performs pre-discharge. Here, the number of pre-discharge shots X is set to 500. Next, in S633, the CPU 300 obtains the temperature (Ti2n) of the recording head 10 after the pre-discharge is performed using the temperature sensor 18. Then, proceeding to S634, the CPU 300 calculates the difference between the temperature value (T1n) obtained in S630 and the temperature value (Ti2n) obtained in S633 to obtain the temperature rise amount (ΔTi2n) due to pre-discharge. Then, proceeding to S635, the CPU 300 performs the calculation (A=X+A) to obtain the cumulative value A, updates the cumulative value A, and also increments the variable (i) by 1. Then, proceeding to S637, the CPU 300 determines whether the cumulative value A exceeds a predetermined value (5000 in this case), and if it does not, proceeds to S632 to execute the aforementioned process. In this way, the temperature rise amount (ΔT2n) of the recording head 10 after performing a predetermined number of pre-discharges can be determined. The relationship between the number of pre-discharges and the temperature rise amount obtained here is stored in RAM 302, etc.

[0061] This process results in the acquisition of two temperature rise values: the reference temperature rise of the recording head 10 under normal conditions (ΔT1n), measured in S601 to S607, and the temperature rise value (ΔT2n) measured in S630 to S637 (the temperature rise value to be judged under normal conditions).

[0062] Then, returning to Figure 6A(c), the process proceeds to S623, where the CPU 300 compares the reference temperature rise amount (ΔT1n) in the normal state measured in Figure 6A(a) with the temperature rise amount (ΔT2n) that is the target of judgment in the normal state measured in Figure 6B(a). Here, the CPU 300 performs a difference calculation. That is, it calculates (ΔT2n - ΔT1n) and determines whether the difference is greater than or equal to a predetermined threshold (Tth) stored in the ROM 301. If it is determined to be greater than or equal to the threshold, the process proceeds to S626, where the CPU 300 executes a suction recovery operation of the recording head 10 and terminates this process. On the other hand, if it is determined that the difference is less than the threshold, the process terminates without performing a suction recovery of the recording head 10. In Embodiment 2, the predetermined threshold (Tth) is set to, for example, 6°C, and the suction recovery operation is executed if the temperature rise is 6°C or higher than the reference temperature rise amount in the normal state. Furthermore, the suction recovery operation performed in S626 is carried out by driving the recovery motor 308 via the recovery processing control circuit 307.

[0063] Figure 7(d) is a graph showing the temperature rise when a suction recovery operation is performed. The horizontal axis represents the number of pre-discharge shots, and the vertical axis represents the temperature rise. The solid line in the figure shows the reference temperature rise (ΔT1n) in the normal state measured in S601 to S607, which corresponds to Figure 7(a). The dotted line shows the threshold temperature rise (a temperature 6°C higher than the reference temperature rise plotted), and the dashed line shows the temperature rise (ΔT2n) that is the target of judgment in the normal state measured in S630 to S637 in Figure 6B(a). In Figure 7(d), the temperature rise that is the target of judgment in the normal state is higher than the threshold temperature rise, so a suction recovery operation is required in this case.

[0064] In this example, the suction recovery operation is performed when the temperature rise of the target under normal conditions exceeds the threshold. However, the suction recovery operation may also be designed with multiple suction intensities, and the suction intensity may be changed according to the difference from the threshold.

[0065] On the other hand, Figure 7(c) shows a graph representing the temperature rise when the suction recovery operation is not performed. The notation in the figure is the same as in Figure 7(d). As shown in the figure, the temperature rise amount (ΔT2n) that is the target of the judgment in the normal state is low compared to the threshold temperature rise amount, so in this case the suction recovery operation is unnecessary.

[0066] Figure 6B(b) is a flowchart illustrating the process of acquiring the temperature rise associated with the pre-discharge of the recording head 10 when transitioning to measuring the temperature rise in the heat storage state as shown in S624 of Figure 6A(c).

[0067] In S640, the recording head 10 is temperature-controlled to the temperature (T1h) measured in S610 (in Embodiment 2, T1h is set to 50°C). The temperature control of the recording head 10 here is performed using the heater 17 and temperature sensor 18 based on the measured temperature information stored in RAM 302 in S610. Next, in S641, the CPU 300 reads the number of pre-discharged shots X that has been previously stored in ROM 301 and stores it in the variable (X) of RAM 302, initializes the variable (A) of RAM 302 that stores the cumulative number of pre-discharges to 0, and sets the variable (i) to 1. Next, in S642, the CPU 300 provides the pre-discharge conditions read in S641 to the recording head drive control circuit 310 and executes the pre-discharge of the recording head 10. Here, the number of pre-discharged shots X is set to, for example, 500. Next, proceeding to S643, the CPU 300 obtains the temperature (Ti2h) of the recording head 10 after the pre-discharge is performed using the temperature sensor 18. Next, proceeding to S644, the CPU 300 performs a calculation (Ti2h-T1h) to take the difference between the temperatures obtained in S640 and S643, and obtains the amount of temperature rise due to pre-discharge (ΔTi2h=Ti2h-T1h). Next, proceeding to S645, the CPU 300 updates the cumulative value A of the number of pre-discharges and increments the variable (i) by 1. Specifically, the set number of pre-discharges is added to the stored cumulative value A (A=A+X). Then, proceeding to S646, the CPU 300 determines whether the cumulative value A has exceeded a predetermined number (for example, 5000 in this case). If it has not exceeded the predetermined number, proceeding to S642, pre-discharge is performed again, and the amount of temperature rise is measured. On the other hand, if the cumulative value A has exceeded the predetermined number, this process is terminated. The relationship between the number of pre-discharged shots and the temperature rise obtained here is stored in RAM302 or similar.

[0068] This process results in the acquisition of two temperature rise values: the reference temperature rise (ΔT1h) in the heat storage state, measured in S610-S616, and the temperature rise (ΔT2h) (the temperature rise value to be judged in the heat storage state), measured in S640-S646.

[0069] Then, returning to Figure 6A(c), the process proceeds to S625, where the CPU 300 compares the reference temperature rise amount (ΔT1h) in the heat storage state with the temperature rise amount (ΔT2h) that is the target of the judgment in the heat storage state. Here, the CPU 300 performs a difference calculation between the two, that is, it calculates (ΔT2h - ΔT1h). It then determines whether the difference is greater than or equal to a predetermined threshold (Tth) stored in the ROM 301, and if it is, the process proceeds to S626 to execute the suction recovery operation of the recording head 10. On the other hand, if it is not greater than or equal to the threshold, the process ends without performing the suction recovery. In Embodiment 2, the predetermined threshold is set to 6°C, and the suction recovery operation is executed if the temperature rise is 6°C or higher than the reference temperature rise amount in the heat storage state.

[0070] Figure 7(f) is a graph showing the temperature rise when the suction recovery operation is performed. The horizontal axis represents the number of pre-discharge shots, and the vertical axis represents the temperature rise. The solid line in the figure represents the standard temperature rise (ΔT1h) in the heat storage state measured in S601 to S607, and the dotted line represents the threshold temperature rise (a temperature 6°C higher than the standard temperature rise plotted). Furthermore, the dashed line represents the temperature rise (ΔT2h) that is the target of judgment in the normal state measured in S630 to S637.

[0071] In Figure 7(f), the temperature rise of the target object (ΔT2h) in the heat storage state is higher than the threshold temperature rise, so in this case, a suction recovery operation is necessary. Here, the suction recovery operation is performed when the temperature rise of the target object in the heat storage state becomes larger than the threshold, but the suction recovery operation may also be designed with multiple suction intensities, and the suction intensity may be changed according to the difference from the threshold.

[0072] On the other hand, Figure 7(e) shows a graph representing the temperature rise when the suction recovery operation is not performed. The notation in the figure is the same as in Figure 7(f). In Figure 7(e), the temperature rise amount (ΔT2h) that is the target of the judgment in the heat storage state is low compared to the threshold temperature rise amount, so in this case the suction recovery operation is unnecessary.

[0073] As described above, Embodiment 2, like Embodiment 1, uses temperature rise amounts measured at two different timings to determine whether or not to perform a recovery operation. Furthermore, at the time of determination, the temperature rise amount to be determined is compared with a reference temperature rise amount based on actual measurements, rather than with a predicted value based on a theoretical formula. This makes it possible to detect a fuzzy, non-discharge state without being affected by variations in material, etc., that exist for each recording head. This has the effect of enabling the recovery operation to be performed at the appropriate timing.

[0074] Furthermore, after a recording operation, the recording head may remain in a heat-retaining state depending on the recording conditions. The temperature rise of the recording head in a heat-retaining state differs from the temperature rise of a recording head that has acclimatized to the ambient temperature. Therefore, if the temperature rise of a recording head that has acclimatized to the ambient temperature is used as the comparison standard, as in Embodiment 1, it may lead to false detection of a non-discharge state. To avoid such false detections, a method of dissipating the heat-retaining recording head until it reaches the ambient temperature can be considered, but this may increase the dissipation time, leading to a decrease in processing throughput. Therefore, in Embodiment 2, the temperature rise amount that serves as the standard for the heat-retaining state and the temperature rise amount of the target for determining the heat-retaining state are obtained and compared to determine whether to perform a recovery operation on the recording head. This has the effect of preventing the false detections and decrease in processing throughput mentioned above.

[0075] [Embodiment 3] Next, Embodiment 3 of the present invention will be described. Embodiment 3 will be described as an example in which the determination criterion in the step of determining whether or not to perform the suction recovery operation of Embodiment 2 described above is determined based on the total amount of heat applied to the heater 17 in the recording operation immediately preceding the recovery operation sequence. Note that the configuration of the inkjet recording device according to Embodiment 3 is the same as that of Embodiment 1 described above, so its description will be omitted.

[0076] Figure 8A is a flowchart illustrating the non-discharge detection and recovery process in the inkjet recording device 100 according to Embodiment 3. Figures 8A(a) and (b) are flowcharts illustrating the process of measuring a reference temperature rise multiple times, and Figure 8A(c) is a flowchart illustrating the process of determining whether to perform an suction recovery operation and executing the recovery process. Figure 8B(a) is a flowchart illustrating the acquisition process of ΔT2n in S821 of Figure 8A(c), and Figure 8B(b) is a flowchart illustrating the acquisition process of ΔT2h in S824 of Figure 8A(c). The processes shown in these flowcharts are realized by the CPU 300 executing a program stored in the ROM 301.

[0077] First, the flowcharts in Figures 8A(a) and 8A(b) are the same as those in Figures 4(a) and 4A(b) of Embodiment 1, and Figures 6A(a) and 6A(b) of Embodiment 2, so a detailed explanation will be omitted. In Embodiment 3, multiple reference temperature rise amounts are also acquired. Therefore, the acquisition sequences S801-S807 and S810-S816 in Figure 8A related to Embodiment 3 are the same as, for example, S601-S607 and S610-S616 described in Embodiment 2. The results obtained are the same as, for example, Figure 7(a).

[0078] Next, referring to the flowchart in Figure 8A(c), the process for determining whether to proceed to the execution determination of the suction recovery operation and executing the recovery operation according to Embodiment 3 will be explained. In Embodiment 3, the total amount of heat supplied to the heater 17 in the immediately preceding recording operation is used. This total amount of heat is calculated based on the driving conditions of the recording head 10 supplied to the heater 17. Specifically, for example, it is calculated by performing calculation processing based on the voltage applied to the recording head 10 when the recording head 10 is driven, the application time, and the resistance value of the heater 17.

[0079] First, in S820, the CPU300 calculates the total heat (Qtotal) generated during the most recent recording operation and compares this calculated total heat with a threshold (Qth) pre-stored in the ROM301. If it determines that the total heat (Qtotal) exceeds the threshold (Qth), it proceeds to S823 to execute the process for determining the state of heat accumulation. On the other hand, if it determines that the total heat (Qtotal) does not exceed the threshold (Qth), it proceeds to S821 to execute the process for determining the state of normal operation.

[0080] Figure 8B(a) is a flowchart illustrating the normal state determination process in S821 of Figure 8A(c).

[0081] First, in S830, the CPU 300 adjusts the temperature of the recording head 10 to the temperature (T1n) measured in S801. This temperature adjustment of the recording head is performed using the heater 17 and temperature sensor 128 based on the measured temperature information stored in RAM 302 in S801. Next, in S831, the CPU 300 reads the number of spare ejections X stored in ROM 301 and stores it in the variable (X) in RAM 302. It also initializes the variable (A) in RAM 302, which stores the cumulative value A of spare ejections, to 0, and sets the variable (i) in RAM 302, which counts the number of measurements, to 1.

[0082] Next, in S832, the CPU 300 provides the conditions read in S831 to the recording head drive control circuit 310 to perform pre-discharge of the recording head 10. Here, the number of pre-discharged shots is set to, for example, 500. Next, in S833, the CPU 300 obtains the temperature (Ti2n) of the recording head 10 after the pre-discharge is performed using the temperature sensor 18. Next, in S834, the CPU 300 calculates the difference (Ti2n-T1n) between the temperature (T1n) obtained in S830 and the temperature (Ti2n) obtained in S833 to obtain the amount of temperature rise of the recording head 10 due to pre-discharge. Next, in S835, the CPU 300 updates the cumulative value A of the number of pre-discharged shots and the variable (i). Specifically, the set number of pre-discharged shots X is added to the stored cumulative value A (A=A+X), and the variable (i) is incremented by 1. Then, in S836, the CPU300 determines whether the cumulative value A is equal to or greater than a predetermined threshold (in this case, 5000). If it determines that it is equal to or greater than the predetermined threshold, this process ends; otherwise, it proceeds to S832, where, for example, 500 preliminary ejections are performed, and the same document as described above is executed.

[0083] In Embodiment 3, the relationship between the cumulative number of pre-discharged shots obtained here and the temperature rise is stored in RAM 302 or the like. Through the processing up to this point, two temperature rise values ​​have been obtained: the reference temperature rise under normal conditions measured in processing S801 to S807, and the temperature rise measured in S830 to S836 (the temperature rise value to be judged under normal conditions).

[0084] Then, proceeding to S822 in Figure 8A(c), the CPU 300 compares the reference temperature rise amount (ΔT2n) under normal conditions with the temperature rise amount (ΔT1n) under normal conditions that is the target of the judgment. Here, the CPU 300 performs a difference calculation (ΔT2n - ΔT1n) between the two. Then, it determines whether the result exceeds a predetermined threshold (Tth) that is pre-stored in the ROM 301. If it does not exceed the threshold, this process is terminated without performing the suction recovery operation of the recording head 10. On the other hand, if it is determined that it is above the predetermined threshold (Tth), the process proceeds to S825, where the suction recovery operation of the recording head 10 is performed and this process is terminated.

[0085] In Embodiment 3, a predetermined threshold is set to 6°C, and the suction recovery operation is performed when the reference temperature rise amount (ΔT2n) in the normal state is 6°C or higher than the temperature rise amount to be judged (ΔT1n). The suction recovery operation performed in S825 is executed by driving the recovery processing motor 308 via the recovery processing control circuit 307. The determination of whether or not to perform suction recovery is made, for example, in the graphs representing the temperature rise amount, which are the same as in Figures 7(b) and (c), respectively.

[0086] Figure 8B(b) illustrates the process when the system proceeds to determine the heat storage state in S823 of Figure 8A(c). In S823, the CPU 300 measures the amount of temperature rise associated with pre-discharge in the heat storage state.

[0087] First, in S840, the CPU 300 adjusts the temperature of the recording head to the temperature (T1h) measured in S810. The temperature adjustment of the recording head is performed using the heater 17 and temperature sensor 18 based on the measured temperature information stored in RAM 302 in S810. Next, in S841, the CPU 300 reads the number of pre-discharged shots X, which is stored in ROM 301, and stores it in the variable (X) of RAM 302. It also initializes the variable (A) of RAM 302, which stores the cumulative number of pre-discharges, to 0 and sets the variable (i) to 1. Next, in S842, the CPU 300 provides the conditions read in S841 to the recording head drive control circuit 310 and performs pre-discharge of the recording head 10. Here, the number of pre-discharged shots X is set to 500. Next, in S843, the CPU 300 obtains the temperature (Ti2h) of the recording head 10 after the pre-discharge is performed using the temperature sensor 18. Then, proceeding to S844, the CPU300 calculates the difference between the temperature (T1h) obtained in S840 and the temperature (Ti2h) obtained in S843 to obtain the temperature rise due to pre-discharge (ΔTi2h). Then, proceeding to S845, the CPU300 updates the cumulative value A of the number of pre-discharges and the variable (i). Specifically, it adds the set number of pre-discharges to the stored cumulative value A (A=A+X) and increments the variable (i) by 1. Then, proceeding to S846, the CPU300 determines whether the cumulative value A of the number of pre-discharges is greater than or equal to a predetermined value, for example, 5000. If it is not greater than or equal to the predetermined value, proceeding to S842, pre-discharge is performed again and the temperature rise is measured. On the other hand, if it is greater than or equal to the predetermined value, this process ends.

[0088] The relationship between the number of reserve discharges and the temperature rise obtained here is stored in RAM302, etc. This process yields two values: the reference temperature rise (ΔT1h) in the heat storage state measured in S810~S816, and the temperature rise (ΔT2h) (the temperature rise to be judged in the heat storage state) measured in S840~S846.

[0089] Then, proceeding to S824 in Figure 8A(c), the CPU 300 compares the reference temperature rise amount (ΔT1h) in the heat storage state with the temperature rise amount (ΔT2h) that is the target of the determination in the heat storage state. Here, the CPU 300 performs a difference calculation (ΔT2h - ΔT1h) between the two. If the difference is greater than or equal to a predetermined threshold stored in the ROM 301, proceed to S825 and execute the suction recovery operation of the recording head 10. On the other hand, if the difference is less than the predetermined threshold, the suction recovery is not performed and this process is terminated.

[0090] In Embodiment 3, a predetermined threshold is set to 6°C, and the suction recovery operation is performed if the temperature rise is 6°C or more higher than the reference temperature rise in the heat storage state. The graphs showing the temperature rise results with and without suction recovery are the same as those in Figures 7(d) and (e).

[0091] As described above, Embodiment 3, like Embodiments 1 and 2, utilizes temperature rise measured at two different timings to determine whether to execute the recovery operation. When determining whether to execute the recovery operation, the temperature rise of the target is compared with a reference temperature rise based on actual measurements, rather than with a predicted value based on a theoretical formula. This allows for detection of the non-discharge state without being affected by variations in material, etc., present in each recording head, and enables the execution of the recovery operation at a more appropriate timing. Also, similar to Embodiment 2, obtaining a reference temperature rise in the heat storage state as the reference temperature rise helps prevent false detections and a decrease in processing throughput.

[0092] Furthermore, in Embodiment 3, the total amount of heat supplied to the heater during the previous recording operation is used to determine whether or not to perform a recovery operation. In Embodiment 2, when determining whether or not to perform a recovery operation, two parameters, the number of recording dots and the capping time, were used to select between the normal state and the heat storage state. In contrast, as in Embodiment 3, by using the total amount of heat as a parameter for the determination transition, it is possible to select either the normal state or the heat storage state in only one conditional branching step compared to Embodiment 2. This is expected to further improve processing throughput.

[0093] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0094] This specification and drawings disclose the following inkjet recording apparatus and its control method.

[0095] [Item 1] An inkjet recording apparatus comprising a recording head having a plurality of ejection ports for ejecting ink, a temperature detection means for detecting the temperature of the recording head, and a recovery means for performing a recovery operation of the recording head, At the first timing, a first acquisition means acquires the first temperature rise amount associated with the ejection operation of the recording head using the temperature detection means, A second acquisition means acquires, by the temperature detection means, a second temperature rise amount associated with the ejection operation of the recording head at a second timing different from the first timing, A control means that controls the recovery means to perform a recovery operation of the recording head when the second temperature rise is greater than or equal to a predetermined value than the first temperature rise, An inkjet recording apparatus characterized by having the following features.

[0096] [Item 2] The inkjet recording apparatus according to item 1, characterized in that the first timing is immediately after the recording head is filled with ink, or immediately after the recording head has been restored.

[0097] [Item 3] The inkjet recording apparatus according to item 1 or 2, characterized in that the second timing is determined based on the number of ink dots ejected from the recording head, or the elapsed time since the second acquisition means acquired the first temperature rise amount.

[0098] [Item 4] The inkjet recording apparatus according to any one of items 1 to 3, characterized in that the temperature of the recording head when the second acquisition means starts the process of acquiring the second temperature rise is approximately equal to the temperature of the recording head detected by the temperature detection means when the first acquisition means starts the process of acquiring the first temperature rise.

[0099] [Item 5] The inkjet recording apparatus according to any one of items 1 to 4, further characterized in that the control means changes the intensity of the recovery operation according to the predetermined value when the second temperature rise is greater than or equal to the first temperature rise.

[0100] [Item 6] The inkjet recording apparatus according to any one of items 1 to 5, characterized in that the first acquisition means acquires the first temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

[0101] [Item 7] The inkjet recording apparatus according to any one of items 1 to 6, characterized in that the second acquisition means acquires the second temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

[0102] [Item 8] The system further includes a third acquisition means that, when the recording head is in a heat-storage state at a temperature higher than the ambient temperature in which the recording head is located, acquires a third temperature rise amount associated with the ejection operation of the recording head at a third timing, and acquires a fourth temperature rise amount at a fourth timing different from the third timing. The inkjet recording apparatus according to any one of items 1 to 7, characterized in that the control means controls the recovery means to perform a recovery operation of the recording head when the fourth temperature rise is greater than or equal to a predetermined value than the third temperature rise in the heat storage state.

[0103] [Item 9] A counting means for counting the number of dots recorded by the recording head, The system further includes a timing means for timing the capping time of the recording head after the first timing. The inkjet recording apparatus according to item 8, further characterized in that the control means controls the recovery operation based on either the first temperature rise amount and the second temperature rise amount, or the third temperature rise amount and the fourth temperature rise amount, depending on the number of dots and the capping time.

[0104] [Item 10] The inkjet recording apparatus according to item 9, characterized in that the control means controls the recovery operation based on the third temperature rise and the fourth temperature rise when the number of dots is greater than or equal to a predetermined value and the capping time is shorter than a predetermined time.

[0105] [Item 11] The system further includes a fourth acquisition means for acquiring the total heat of the recording head based on the driving conditions of the recording head, The inkjet recording apparatus according to item 8, further characterized in that the control means controls the recovery means to perform a recovery operation of the recording head when the total heat amount is above a predetermined threshold and the fourth temperature rise is above a predetermined value than the third temperature rise.

[0106] [Item 12] The inkjet recording apparatus according to item 11, characterized in that the fourth acquisition means acquires the total heat quantity based on the voltage applied to the heater of the recording head, the application time of the voltage, and the resistance value of the heater.

[0107] [Item 13] A control method for an inkjet recording apparatus comprising a recording head having a plurality of ejection ports for ejecting ink, a temperature detection means for detecting the temperature of the recording head, and a recovery means for performing a recovery operation of the recording head, The first acquisition means includes a first acquisition step in which, at a first timing, the first temperature rise amount associated with the ejection operation of the recording head is acquired by the temperature detection means, The second acquisition means includes a second acquisition step in which, at a second timing different from the first timing, the second temperature rise amount associated with the ejection operation of the recording head is acquired by the temperature detection means, A control step in which the control means controls the recovery means to perform a recovery operation of the recording head when the second temperature rise amount is greater than or equal to a predetermined value than the first temperature rise amount, A control method characterized by having the following features.

[0108] [Item 14] The control method according to item 13, characterized in that the first timing is immediately after ink is filled into the recording head, or immediately after a recovery operation of the recording head is performed.

[0109] [Item 15] The control method according to item 13 or 14, characterized in that the second timing is determined based on the number of ink dots ejected from the recording head, or the elapsed time since the second acquisition step acquired the first temperature rise amount.

[0110] [Item 16] The control method according to any one of items 13 to 15, characterized in that the temperature of the recording head when the second acquisition step starts the process of acquiring the second temperature rise is approximately equal to the temperature of the recording head detected by the temperature detection means when the first acquisition step starts the process of acquiring the first temperature rise.

[0111] [Item 17] The control method according to any one of items 13 to 16, further characterized in that if the amount of the second temperature rise is greater than or equal to a predetermined value than the amount of the first temperature rise, the intensity of the recovery operation is changed according to the predetermined value.

[0112] [Item 18] The control method according to any one of items 13 to 17, characterized in that the first acquisition step is to acquire the first temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

[0113] [Item 19] The control method according to any one of items 13 to 18, characterized in that the second acquisition step is to acquire the second temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

[0114] [Item 20] The third acquisition means further includes a third acquisition step of acquiring a third temperature rise amount associated with the ejection operation of the recording head at a third timing when the recording head is in a heat storage state at a temperature higher than the ambient temperature in which the recording head is located, and acquiring a fourth temperature rise amount at a fourth timing different from the third timing. The control step is characterized in that, in the heat storage state, the recovery means controls the recording head to perform a recovery operation when the fourth temperature rise is greater than or equal to a predetermined value than the third temperature rise. This is the control method according to any one of items 13 to 19.

[0115] [Item 21] The counting means includes a counting step of counting the number of dots recorded by the recording head, The timing means further includes a timing step of timing the capping time of the recording head after the first timing. The control method according to item 20, characterized in that the control step further controls the recovery operation based on either the first temperature rise amount and the second temperature rise amount, or the third temperature rise amount and the fourth temperature rise amount, depending on the number of dots and the capping time.

[0116] [Item 22] The control method according to item 21, characterized in that the control step controls the recovery operation based on the third temperature rise and the fourth temperature rise when the number of dots is greater than or equal to a predetermined value and the capping time is shorter than a predetermined time.

[0117] [Item 23] The fourth acquisition means further includes a fourth acquisition step of acquiring the total heat of the recording head based on the driving conditions of the recording head, The control method according to item 21, further characterized in that the control step controls the recovery means to perform a recovery operation of the recording head when the total heat amount is above a predetermined threshold and the fourth temperature rise is above a predetermined value than the third temperature rise.

[0118] [Item 24] The control method according to item 23, characterized in that the fourth acquisition step acquires the total heat quantity based on the voltage applied to the heater of the recording head, the application time of the voltage, and the resistance value of the heater.

[0119] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public. [Explanation of symbols]

[0120] S…Recording medium, 10…Recording head, 11…Ejector, 12…Substrate, 13…Common liquid chamber, 14…Liquid supply port, 15…Liquid supply channel, 16…Ejector plate, 17…Heater, 18…Temperature sensor, 19…Heat storage layer, 20…Individual wiring, 21…Interlayer insulating film, 22…Passivation layer, 23…Cavitation-resistant film, 100…Inkjet recording device, 101…Drive motor, 102…Drive belt, 200…Recovery unit, 201…Cap, 202…Suction pump, 300…CPU, 301…ROM, 302…RAM, 303…Image input unit, 304…Image signal processing unit, 305…Operation unit, 306…Main bus, 307…Recovery processing control circuit, 308…Recovery processing motor, 309…Cleaning blade, 310…Recording head drive control circuit, 311…Dot counter, 312…Temperature acquisition timer, 313…Capping timer

Claims

1. An inkjet recording apparatus comprising a recording head having a plurality of ejection ports for ejecting ink, a temperature detection means for detecting the temperature of the recording head, and a recovery means for performing a recovery operation of the recording head, At the first timing, a first acquisition means acquires the first temperature rise amount associated with the ejection operation of the recording head using the temperature detection means, A second acquisition means acquires, at a second timing different from the first timing, the amount of the second temperature rise associated with the ejection operation of the recording head, using the temperature detection means. A control means that controls the recovery means to perform a recovery operation of the recording head when the second temperature rise is greater than or equal to a predetermined value than the first temperature rise, An inkjet recording apparatus characterized by having the following features.

2. The inkjet recording apparatus according to claim 1, characterized in that the first timing is immediately after the recording head is filled with ink, or immediately after the recording head is restored.

3. The inkjet recording apparatus according to claim 1, characterized in that the second timing is determined based on the number of ink dots ejected from the recording head, or the elapsed time since the second acquisition means acquired the first temperature rise amount.

4. The inkjet recording apparatus according to claim 1, characterized in that the temperature of the recording head when the second acquisition means starts the process of acquiring the second temperature rise is approximately equal to the temperature of the recording head detected by the temperature detection means when the first acquisition means starts the process of acquiring the first temperature rise.

5. The inkjet recording apparatus according to claim 1, further characterized in that the control means changes the intensity of the recovery operation according to the predetermined value when the second temperature rise is greater than or equal to the first temperature rise.

6. The inkjet recording apparatus according to claim 1, characterized in that the first acquisition means acquires the first temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

7. The inkjet recording apparatus according to claim 1, characterized in that the second acquisition means acquires the second temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

8. The system further includes a third acquisition means that, when the recording head is in a heat-storage state at a temperature higher than the ambient temperature in which the recording head is located, acquires a third temperature rise amount associated with the ejection operation of the recording head at a third timing, and acquires a fourth temperature rise amount at a fourth timing different from the third timing. The inkjet recording apparatus according to claim 1, characterized in that the control means controls the recovery means to perform a recovery operation of the recording head when the fourth temperature rise is greater than or equal to a predetermined value than the third temperature rise in the heat storage state.

9. A counting means for counting the number of dots recorded by the recording head, The system further includes a timing means for timing the capping time of the recording head after the first timing. The inkjet recording apparatus according to claim 8, further characterized in that the control means controls the recovery operation based on either the first temperature rise amount and the second temperature rise amount, or the third temperature rise amount and the fourth temperature rise amount, depending on the number of dots and the capping time.

10. The inkjet recording apparatus according to claim 9, characterized in that the control means controls the recovery operation based on the third temperature rise and the fourth temperature rise when the number of dots is greater than or equal to a predetermined value and the capping time is shorter than a predetermined time.

11. The system further includes a fourth acquisition means for acquiring the total heat of the recording head based on the driving conditions of the recording head, The inkjet recording apparatus according to claim 8, further characterized in that the control means controls the recovery means to perform a recovery operation of the recording head when the total heat amount is above a predetermined threshold and the fourth temperature rise is above a predetermined value than the third temperature rise.

12. The inkjet recording apparatus according to claim 11, characterized in that the fourth acquisition means acquires the total heat amount based on the voltage applied to the heater of the recording head, the application time of the voltage, and the resistance value of the heater.

13. A control method for an inkjet recording apparatus comprising a recording head having a plurality of ejection ports for ejecting ink, a temperature detection means for detecting the temperature of the recording head, and a recovery means for performing a recovery operation of the recording head, The first acquisition means includes a first acquisition step in which, at a first timing, the first temperature rise amount associated with the ejection operation of the recording head is acquired by the temperature detection means, The second acquisition means includes a second acquisition step in which, at a second timing different from the first timing, the second temperature rise amount associated with the ejection operation of the recording head is acquired by the temperature detection means, A control step in which the control means controls the recovery means to perform a recovery operation of the recording head when the second temperature rise amount is greater than or equal to a predetermined value than the first temperature rise amount, A control method characterized by having the following features.

14. The control method according to claim 13, characterized in that the first timing is immediately after the recording head is filled with ink, or immediately after the recording head is restored.

15. The control method according to claim 13, characterized in that the second timing is determined based on the number of ink dots ejected from the recording head, or the elapsed time since the second acquisition step acquired the first temperature rise amount.

16. The control method according to claim 13, characterized in that the temperature of the recording head when the second acquisition step starts the process of acquiring the second temperature rise is approximately equal to the temperature of the recording head detected by the temperature detection means when the first acquisition step starts the process of acquiring the first temperature rise.

17. The control method according to claim 13, further characterized in that if the amount of the second temperature rise is greater than or equal to a predetermined value than the amount of the first temperature rise, the intensity of the recovery operation is changed according to the predetermined value.

18. The control method according to claim 13, characterized in that the first acquisition step is to acquire the first temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

19. The control method according to claim 13, characterized in that the second acquisition step is to acquire the second temperature rise amount by performing preliminary ejection by the recording head a predetermined number of times.

20. The third acquisition means further includes a third acquisition step of acquiring a third temperature rise amount associated with the ejection operation of the recording head at a third timing when the recording head is in a heat storage state at a temperature higher than the ambient temperature in which the recording head is located, and acquiring a fourth temperature rise amount at a fourth timing different from the third timing. The control step is characterized in that, in the heat storage state, the recovery means controls the recording head to perform a recovery operation when the fourth temperature rise is greater than or equal to a predetermined value than the third temperature rise.

21. The counting means includes a counting step of counting the number of dots recorded by the recording head, The timing means further includes a timing step of timing the capping time of the recording head after the first timing. The control method according to claim 20, wherein the control step further controls the recovery operation based on either the first temperature rise amount and the second temperature rise amount, or the third temperature rise amount and the fourth temperature rise amount, depending on the number of dots and the capping time.

22. The control method according to claim 21, characterized in that the control step controls the recovery operation based on the third temperature rise and the fourth temperature rise when the number of dots is greater than or equal to a predetermined value and the capping time is shorter than a predetermined time.

23. The fourth acquisition means further includes a fourth acquisition step of acquiring the total heat of the recording head based on the driving conditions of the recording head, The control method according to claim 21, further characterized in that the control step controls the recovery means to perform a recovery operation of the recording head when the total heat amount is above a predetermined threshold and the fourth temperature rise is above a predetermined value than the third temperature rise.

24. The control method according to claim 23, characterized in that the fourth acquisition step acquires the total heat amount based on the voltage applied to the heater of the recording head, the application time of the voltage, and the resistance value of the heater.

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