Inkjet recording apparatus and inkjet recording method

Abstract

To shorten time required for detection of an ink discharge state and recovery operation for recovering the ink discharge state.SOLUTION: An inkjet recording device concurrently carries out circulation of ink through a circulation flow passage between a recording head and an ink tank, and detection operation for detecting an ink discharge state at a discharge port of the recording head.SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to an inkjet recording apparatus and an inkjet recording method using a recording head that discharges ink to record an image.

Background Art

[0002] Patent Document 1 describes detecting the discharge state of ink in a recording head, and when it is not detected that the discharge state of ink is good, performing a recovery operation to recover the discharge state of ink, and then detecting the discharge state of ink again.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, since the detection of the discharge state of ink and the recovery operation for recovering the discharge state of ink are performed in order, it takes time until it is detected that the discharge state is good.

[0005] The present invention has been made in view of the above problems, and aims to shorten the time required for detecting the discharge state of ink and the recovery operation for recovering the discharge state of ink.

Means for Solving the Problems

[0006] The inkjet recording apparatus of the present invention includes a discharge port for discharging ink, an energy generating element provided corresponding to the discharge port for generating energy used to discharge ink, a pressure chamber located at a position facing the energy generating element, a recording head having the pressure chamber, a detection means for performing a detection operation of detecting the discharge state of the ink from the discharge port, a circulation means for circulating the ink so as to pass through the pressure chamber, and a control means for executing the circulation operation of the ink by the circulation means and the detection operation by the detection means in parallel. When the control means ends the detection operation, if the next operation to be executed does not involve ink circulation, the control means stops the ink circulation by the circulation means, and if the next operation involves the ink circulation, the control means continues the ink circulation by the circulation means even after the detection operation stops.

Advantages of the Invention

[0007] According to the present invention, by executing the recovery operation and the detection operation in parallel, the time until it is detected that the discharge state of the recording head becomes good can be shortened.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 18

Figure 19

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0010] (First Embodiment) FIG. 1 is an internal configuration diagram of an inkjet recording apparatus 1 (hereinafter, recording apparatus 1) used in this embodiment. In the figure, the x direction is the horizontal direction, the y direction (perpendicular to the paper surface) is the direction in which ejection ports are arranged in a recording head 8 described later, and the z direction is the vertical direction, respectively.

[0011] The recording device 1 is a multifunction machine equipped with a printing unit 2 and a scanner unit 3, and can execute various processes related to the recording operation and the reading operation, either individually or in conjunction, by the printing unit 2 and the scanner unit 3. The scanner unit 3 is equipped with an ADF (Auto Document Feeder) and an FBS (Flatbed Scanner), and can read the document automatically fed by the ADF and the document placed on the platen of the FBS by the user (scan). Note that although this embodiment is a multifunction machine having both the printing unit 2 and the scanner unit 3, it may also be in a form without the scanner unit 3. FIG. 1 shows the standby state where the recording device 1 is not performing either the recording operation or the reading operation.

[0012] In the printing unit 2, a first cassette 5A and a second cassette 5B for accommodating a recording medium (cut sheet) S are detachably installed at the bottom of the housing 4 in the vertical downward direction. Relatively small recording media up to A4 size are accommodated in the first cassette 5A, and relatively large recording media up to A3 size are accommodated in the second cassette 5B in a flat stack. Near the first cassette 5A, a first feeding unit 6A for separating and feeding the accommodated recording media one by one is provided. Similarly, a second feeding unit 6B is provided near the second cassette 5B. When the recording operation is performed, the recording medium S is selectively fed from either one of the cassettes.

[0013] The conveyance roller 7, the discharge roller 12, the pinch roller 7a, the accelerator 7b, the guide 18, the inner guide 19, and the flapper 11 are a conveyance mechanism for guiding the recording medium S in a predetermined direction. The conveyance roller 7 is arranged on the upstream side and the downstream side of the recording head 8, and is a driving roller driven by a conveyance motor (not shown). The pinch roller 7a is a driven roller that rotates by nipping the recording medium S together with the conveyance roller 7. The discharge roller 12 is arranged on the downstream side of the conveyance roller 7, and is a driving roller driven by a conveyance motor (not shown). The accelerator 7b sandwiches and conveys the recording medium S together with the conveyance roller 7 and the discharge roller 12 arranged on the downstream side of the recording head 8.

[0014] The guide 18 is provided in the conveyance path of the recording medium S and guides the recording medium S in a predetermined direction. The inner guide 19 is a member extending in the y direction and having a curved side surface, and guides the recording medium S along the side surface. The flapper 11 is a member for switching the direction in which the recording medium S is conveyed during the duplex recording operation. The discharge tray 13 is a tray for stacking and holding the recording medium S that has completed the recording operation and is discharged by the discharge roller 12.

[0015] The recording head 8 of the present embodiment is a full-line type color inkjet recording head, and a plurality of ejection ports for ejecting ink according to recording data are arranged along the y direction in FIG. 1 by an amount corresponding to the width of the recording medium S. That is, the recording head 8 is configured to be able to eject inks of a plurality of colors. When the recording head 8 is in the standby position, the ejection port surface 8a of the recording head 8 faces vertically downward as shown in FIG. 1 and is capped by the cap unit 10. When performing the recording operation, the orientation of the recording head 8 is changed by a print controller 202, which will be described later, so that the ejection port surface 8a faces the platen 9. The platen 9 is constituted by a flat plate extending in the y direction and supports the recording medium S on which the recording operation is performed by the recording head 8 from the back. The movement of the recording head 8 from the standby position to the recording position will be described in detail later.

[0016] The ink tank unit 14 stores the four colors of ink supplied to the recording head 8 respectively. The ink supply unit 15 is provided in the middle of the flow path connecting the ink tank unit 14 and the recording head 8, and adjusts the pressure and flow rate of the ink in the recording head 8 to an appropriate range. In the present embodiment, a circulation type ink supply system is adopted, and the ink supply unit 15 adjusts the pressure of the ink supplied to the recording head 8 and the flow rate of the ink recovered from the recording head 8 to an appropriate range.

[0017] The maintenance unit 16 includes a cap unit 10 and a wiping unit 17, and operates these at a predetermined timing to perform a maintenance operation on the recording head 8. The maintenance operation will be described in detail later.

[0018] FIG. 2 is a block diagram showing a control configuration in the recording apparatus 1. The control configuration mainly includes a print engine unit 200 that oversees the print unit 2, a scanner engine unit 300 that oversees the scanner unit 3, and a controller unit 100 that oversees the entire recording apparatus 1. The print controller 202 controls various mechanisms of the print engine unit 200 according to instructions from the main controller 101 of the controller unit 100. Various mechanisms of the scanner engine unit 300 are controlled by the main controller 101 of the controller unit 100. Details of the control configuration will be described below.

[0019] In the controller unit 100, the main controller 101 constituted by a CPU controls the entire recording apparatus 1 while using the RAM 106 as a work area according to programs and various parameters stored in the ROM 107. For example, when a print job is input from the host device 400 via the host I / F 102 or the wireless I / F 103, the image processing unit 108 performs predetermined image processing on the received image data according to instructions from the main controller 101. Then, the main controller 101 transmits the image data subjected to image processing to the print engine unit 200 via the print engine I / F 105.

[0020] Note that the recording apparatus 1 may acquire image data from the host device 400 via wireless communication or wired communication, or may acquire image data from an external storage device (such as a USB memory) connected to the recording apparatus 1. The communication methods used for wireless communication and wired communication are not limited. For example, as communication methods used for wireless communication, Wi-Fi (Wireless Fidelity) (registered trademark) and Bluetooth (registered trademark) are applicable. Also, as communication methods used for wired communication, USB (Universal Serial Bus), etc. are applicable. Further, for example, when a read command is input from the host device 400, the main controller 101 transmits this command to the scanner unit 3 via the scanner engine I / F 109.

[0021] The operation panel 104 is a mechanism for the user to perform input and output with respect to the recording apparatus 1. The user can instruct operations such as copying and scanning, set the printing mode, and recognize information of the recording apparatus 1 via the operation panel 104.

[0022] In the print engine unit 200, a print controller 202 constituted by a CPU controls various mechanisms provided in the print unit 2 while using the RAM 204 as a work area according to programs and various parameters stored in the ROM 203. When various commands and image data are received via the controller I / F 201, the print controller 202 temporarily stores them in the RAM 204. So that the recording head 8 can be used for the recording operation, the print controller 202 causes the image processing controller 205 to convert the stored image data into recording data. When the recording data is generated, the print controller 202 causes the recording head 8 to execute a recording operation based on the recording data via the head I / F 206. At this time, the print controller 202 drives the paper feed units 6A, 6B, the conveyance roller 7, the discharge roller 12, and the flapper 11 shown in FIG. 1 via the conveyance control unit 207 to convey the recording medium S. In accordance with the instruction of the print controller 202, a recording operation by the recording head 8 is executed in conjunction with the conveyance operation of the recording medium S, and printing processing is performed.

[0023] The head carriage control unit 208 changes the orientation and position of the recording head 8 according to the operating state such as the maintenance state and the recording state of the recording apparatus 1. The ink supply control unit 209 controls the ink supply unit 15 so that the pressure of the ink supplied to the recording head 8 is within an appropriate range. The maintenance control unit 210 controls the operations of the cap unit 10 and the wiping unit 17 in the maintenance unit 16 when performing a maintenance operation on the recording head 8.

[0024] In the scanner engine unit 300, the main controller 101 controls the hardware resources of the scanner controller 302 while using the RAM 106 as a work area according to the programs and various parameters stored in the ROM 107. As a result, various mechanisms included in the scanner unit 3 are controlled. For example, by the main controller 101 controlling the hardware resources in the scanner controller 302 via the controller I / F 301, the document loaded on the ADF by the user is conveyed via the conveyance control unit 304 and read by the sensor 305. Then, the scanner controller 302 stores the read image data in the RAM 303. Note that the print controller 202 can cause the recording head 8 to execute a recording operation based on the image data read by the scanner controller 302 by converting the image data acquired as described above into recording data.

[0025] FIG. 3 shows the recording apparatus 1 in a recording state. Compared with the standby state shown in FIG. 1, the cap unit 10 is separated from the discharge port surface 8a of the recording head 8, and the discharge port surface 8a faces the platen 9. In the present embodiment, the plane of the platen 9 is inclined at approximately 45 degrees with respect to the horizontal direction, and the discharge port surface 8a of the recording head 8 at the recording position is also inclined at approximately 45 degrees with respect to the horizontal direction so that the distance from the platen 9 is maintained constant.

[0026] When moving the recording head 8 from the standby position shown in FIG. 1 to the recording position shown in FIG. 3, the print controller 202 lowers the cap unit 10 to the retracted position shown in FIG. 3 using the maintenance control unit 210. As a result, the discharge port surface 8a of the recording head 8 is separated from the cap member 10a. Thereafter, the print controller 202 rotates the recording head 8 by 45 degrees while adjusting the vertical height of the recording head 8 using the head carriage control unit 208 so that the discharge port surface 8a faces the platen 9. When the recording operation is completed and the recording head 8 moves from the recording position to the standby position, the print controller 202 performs the reverse process of the above.

[0027] Next, the conveyance path of the recording medium S in the printing unit 2 will be described. When a recording command is input, the print controller 202 first moves the recording head 8 to the recording position shown in FIG. 3 using the maintenance control unit 210 and the head carriage control unit 208. Thereafter, the print controller 202 uses the conveyance control unit 207 to drive either the first feeding unit 6A or the second feeding unit 6B according to the recording command, and feeds the recording medium S.

[0028] FIGS. 4(a) to (c) are diagrams showing the conveyance path when the A4-size recording medium S housed in the first cassette 5A is fed. The recording medium S loaded on the top of the first cassette 5A is separated from the subsequent recording media by the first feeding unit 6A, and is conveyed toward the recording area P between the platen 9 and the recording head 8 while being nipped by the conveyance roller 7 and the pinch roller 7a. FIG. 4(a) shows the conveyance state immediately before the leading edge of the recording medium S reaches the recording area P. The traveling direction of the recording medium S is changed from the horizontal direction (x direction) to a direction inclined by approximately 45 degrees with respect to the horizontal direction while being fed by the first feeding unit 6A and reaching the recording area P.

[0029] In the recording area P, ink is ejected from a plurality of ejection ports provided in the recording head 8 toward the recording medium S. The back surface of the recording medium S in the area where the ink is applied is supported by the platen 9, and the distance between the ejection port surface 8a and the recording medium S is kept constant. After the ink is applied, the recording medium S is guided by the conveyance roller 7 and the flapper 7b, passes through the left side of the flapper 11 with its leading edge tilted to the right, and is conveyed upward in the vertical direction of the recording apparatus 1 along the guide 18. FIG. 4(b) shows the state where the leading edge of the recording medium S passes through the recording area P and is conveyed upward in the vertical direction. The traveling direction of the recording medium S is changed upward in the vertical direction by the conveyance roller 7 and the flapper 7b from the position of the recording area P inclined by approximately 45 degrees with respect to the horizontal direction.

[0030] After the recording medium S is conveyed upward in the vertical direction, it is discharged onto the discharge tray 13 by the discharge roller 12 and the acceleration 7b. FIG. 4(c) shows a state in which the leading end of the recording medium S passes through the discharge roller 12 and is discharged onto the discharge tray 13. The discharged recording medium S is held on the discharge tray 13 with the surface on which the image is recorded by the recording head 8 facing downward.

[0031] Similarly, the A3-sized recording medium S housed in the second cassette 5B is conveyed toward the recording area P between the platen 9 and the recording head 8. That is, the recording medium S loaded on the top of the second cassette 5B is separated from the second and subsequent recording media by the second feeding unit 6B, and is conveyed toward the recording area P between the platen 9 and the recording head 8 while being nipped by the conveyance roller 7 and the pinch roller 7a.

[0032] When performing double-sided recording on the A4-sized recording medium S, the recording operation is performed on the second side (back side) after recording the first side (front side). Since the conveyance process when recording the first side is the same as that shown in FIGS. 4(a) to 4(c), the description thereof is omitted here. When the recording operation on the first side by the recording head 8 is completed and the trailing end of the recording medium S passes through the flapper 11, the print controller 202 rotates the conveyance roller 7 in the reverse direction to convey the recording medium S into the recording apparatus 1. At this time, since the tip of the flapper 11 is controlled by an actuator (not shown) to tilt to the left, the leading end of the recording medium S (the trailing end in the recording operation on the first side) passes through the right side of the flapper 11 and is conveyed downward in the vertical direction.

[0033] Thereafter, the recording medium S is conveyed along the curved outer peripheral surface of the inner guide 19 and is again conveyed to the recording area P between the recording head 8 and the platen 9. At this time, the second side of the recording medium S faces the discharge port surface 8a of the recording head 8. The subsequent conveyance path is the same as that in the case of the first side recording shown in FIGS. 4(b) and 4(c). When the leading end of the recording medium S passes through the recording area P and is conveyed upward in the vertical direction, the flapper 11 is controlled by an actuator (not shown) to move to a position where the tip is tilted to the right.

[0034] Next, the maintenance operation for the recording head 8 will be described. As also described in FIG. 1, the maintenance unit 16 of the present embodiment includes a cap unit 10 and a wiping unit 17, and operates these at a predetermined timing to perform a maintenance operation.

[0035] FIG. 5 is a diagram when the recording apparatus 1 is in a maintenance state. When moving the recording head 8 from the standby position shown in FIG. 1 to the maintenance position shown in FIG. 5, the print controller 202 moves the recording head 8 upward in the vertical direction and moves the cap unit 10 downward in the vertical direction. Then, the print controller 202 moves the wiping unit 17 from the retracted position to the right direction in FIG. 5. Thereafter, the print controller 202 moves the recording head 8 downward in the vertical direction to move it to a maintenance position where the maintenance operation is possible.

[0036] On the other hand, when moving the recording head 8 from the recording position shown in FIG. 3 to the maintenance position shown in FIG. 5, the print controller 202 moves the recording head 8 upward in the vertical direction while rotating it by 45 degrees. Then, the print controller 202 moves the wiping unit 17 from the retracted position to the right direction. Thereafter, the print controller 202 moves the recording head 8 downward in the vertical direction to move it to a maintenance position where the maintenance operation by the maintenance unit 16 is possible.

[0037] Fig. 6(a) is a perspective view showing the maintenance unit 16 in the standby position, and Fig. 6(b) is a perspective view showing the maintenance unit 16 in the maintenance position. Fig. 6(a) corresponds to Fig. 1, and Fig. 6(b) corresponds to Fig. 5. When the recording head 8 is in the standby position, the maintenance unit 16 is in the standby position shown in Fig. 6(a), the cap unit 10 has moved vertically upward, and the wiping unit 17 is housed inside the maintenance unit 16. The cap unit 10 has a box-shaped cap member 10a extending in the y direction, and by bringing this into close contact with the discharge port surface 8a of the recording head 8, evaporation of ink from the discharge port can be suppressed. Further, the cap unit 10 also has a function of collecting the ink discharged by preliminary discharge or the like in the cap member 10a and causing the collected ink to be sucked by a suction pump (not shown).

[0038] On the other hand, in the maintenance position shown in Fig. 6(b), the cap unit 10 has moved vertically downward, and the wiping unit 17 has been pulled out from the maintenance unit 16. The wiping unit 17 includes two wiper units, a blade wiper unit 171 and a vacuum wiper unit 172.

[0039] In the blade wiper unit 171, blade wipers 171a for wiping the discharge port surface 8a along the x direction are arranged in the y direction by a length corresponding to the array region of the discharge ports. When performing a wiping operation using the blade wiper unit 171, the wiping unit 17 moves the blade wiper unit 171 in the x direction in a state where the recording head 8 is positioned at a height at which it can contact the blade wiper 171a. By this movement, ink or the like adhering to the discharge port surface 8a is wiped off by the blade wiper 171a.

[0040] At the entrance of the maintenance unit 16 when the blade wiper 171a is stored, a wet wiper cleaner 16a is provided for removing the ink adhering to the blade wiper 171a and applying a wetting liquid to the blade wiper 171a. Each time the blade wiper 171a is stored in the maintenance unit 16, the adhering substances are removed and the wetting liquid is applied by the wet wiper cleaner 16a. Then, when the discharge port surface 8a is wiped next, the wetting liquid is transferred to the discharge port surface 8a, improving the slipperiness between the discharge port surface 8a and the blade wiper 171a.

[0041] On the other hand, the vacuum wiper unit 172 includes a flat plate 172a having an opening extending in the y direction, a carriage 172b movable in the y direction within the opening, and a vacuum wiper 172c mounted on the carriage 172b. The vacuum wiper 172c is arranged to be able to wipe the discharge port surface 8a in the y direction as the carriage 172b moves. At the tip of the vacuum wiper 172c, a suction port connected to a suction pump (not shown) is formed. Therefore, when the carriage 172b is moved in the y direction while operating the suction pump, the ink and the like adhering to the discharge port surface 8a of the recording head 8 are sucked into the suction port while being wiped by the vacuum wiper 172c. At this time, the positioning pins 172d provided at both ends of the flat plate 172a and the opening are used for aligning the discharge port surface 8a with respect to the vacuum wiper 172c.

[0042] In this embodiment, it is possible to perform a first wiping process in which the wiping operation by the blade wiper unit 171 is performed and the wiping operation by the vacuum wiper unit 172 is not performed, and a second wiping process in which both wiping processes are performed in order. When performing the first wiping process, the print controller 202 first pulls out the wiper unit 17 from the maintenance unit 16 with the recording head 8 retracted vertically upward from the maintenance position in FIG. 5. Then, the print controller 202 moves the recording head 8 vertically downward to a position where it can contact the blade wiper 171a, and then moves the wiper unit 17 into the maintenance unit 16. By this movement, ink or the like adhering to the discharge port surface 8a is wiped off by the blade wiper 171a. That is, the blade wiper 171a wipes the discharge port surface 8a when moving from the position pulled out from the maintenance unit 16 into the maintenance unit 16.

[0043] When the blade wiper unit 171 is housed, the print controller 202 then moves the cap unit 10 vertically upward and brings the cap member 10a into close contact with the discharge port surface 8a of the recording head 8. Then, the print controller 202 drives the recording head 8 in that state to perform preliminary discharge, and sucks the ink collected in the cap member 10a by a suction pump.

[0044] On the other hand, when performing the second wiping process, the print controller 202 first slides and pulls out the wiping unit 17 from the maintenance unit 16 with the recording head 8 retracted vertically upward from the maintenance position shown in FIG. 5. Then, the print controller 202 moves the recording head 8 vertically downward to a position where it can contact the blade wiper 171a, and then moves the wiping unit 17 into the maintenance unit 16. As a result, the wiping operation by the blade wiper 171a is performed on the discharge port surface 8a. Next, the print controller 202 slides and pulls out the wiping unit 17 from the maintenance unit 16 to a predetermined position with the recording head 8 retracted vertically upward from the maintenance position shown in FIG. 5 again. Subsequently, the print controller 202 positions the discharge port surface 8a and the vacuum wiper unit 172 using the flat plate 172a and the positioning pin 172d while lowering the recording head 8 to the wiping position shown in FIG. 5. Thereafter, the print controller 202 executes the wiping operation by the above-described vacuum wiper unit 172. The print controller 202 retracts the recording head 8 vertically upward, stores the wiping unit 17, and then performs a preliminary discharge into the cap member by the cap unit 10 and a suction operation of the recovered ink, similar to the first wiping process.

[0045] (Ink Supply Unit) FIG. 7 is a diagram including the ink supply unit 15 employed in the inkjet recording apparatus 1 of the present embodiment. The flow path configuration of the ink circulation system of the present embodiment will be described with reference to FIG. 7. The ink supply unit 15 supplies the ink supplied from the ink tank unit 14 to the recording head 8. In FIG. 7, the configuration for one color of ink is shown, but in reality, such a configuration is prepared for each ink color. The ink supply unit 15 is basically controlled by the ink supply control unit 209 shown in FIG. 2. Hereinafter, each configuration of the ink supply unit 15 will be described.

[0046] The ink mainly circulates between the sub-tank 151 and the recording head 8. In the recording head 8, an ink ejection operation is performed based on image data, and the ink that is not ejected is recovered back to the sub-tank 151 again.

[0047] The sub-tank 151 that stores a predetermined amount of ink is connected to a supply channel C2 for supplying ink to the recording head 8 and a recovery channel C4 for recovering ink from the recording head 8. That is, the sub-tank 151, the supply channel C2, the recording head 8, and the recovery channel C4 constitute a circulation path that serves as a circulation channel through which the ink circulates. Also, the sub-tank 151 is connected to a channel C0 through which air flows.

[0048] The sub-tank 151 is provided with a liquid level detection means 151a composed of a plurality of electrode pins. The ink supply control unit 209 can grasp the height of the ink liquid level, that is, the remaining amount of ink in the sub-tank 151, by detecting the presence or absence of a conduction current between these plurality of pins. The vacuum pump P0 is a negative pressure generation source for reducing the pressure inside the tank of the sub-tank 151. The atmosphere release valve V0 is a valve for switching whether to communicate the inside of the sub-tank 151 with the atmosphere.

[0049] The main tank 141 is a tank that stores the ink supplied to the sub-tank 151. The main tank 141 is configured to be detachable from the recording apparatus main body. In the middle of the tank connection channel C1 that connects the sub-tank 151 and the main tank 141, a tank supply valve V1 for switching the connection between the sub-tank 151 and the main tank 141 is arranged.

[0050] When the ink supply control unit 209 detects that the ink in the sub-tank 151 has become less than a predetermined amount by the liquid level detection means 151a, it closes the atmosphere release valve V0, the supply valve V2, the recovery valve V4, and the head replacement valve V5. Further, the ink supply control unit 209 opens the tank supply valve V1. In this state, the ink supply control unit 209 operates the decompression pump P0. Then, the inside of the sub-tank 151 becomes negative pressure, and ink is supplied from the main tank 141 to the sub-tank 151. When the liquid level detection means 151a detects that the ink in the sub-tank 151 has exceeded the predetermined amount, the ink supply control unit 209 closes the tank supply valve V1 and stops the decompression pump P0.

[0051] The supply flow path C2 is a flow path for supplying ink from the sub-tank 151 to the recording head 8, and a supply pump P1 and a supply valve V2 are arranged in the middle thereof. During the recording operation, by driving the supply pump P1 with the supply valve V2 open, ink can be circulated in the circulation path while supplying ink to the recording head 8. The amount of ink ejected per unit time by the recording head 8 varies according to the image data. The flow rate of the supply pump P1 is determined so as to be able to cope even when the recording head 8 performs a ejection operation in which the ink consumption per unit time is maximum.

[0052] The relief channel C3 is located upstream of the supply valve V2 and connects the upstream and downstream sides of the supply pump P1. A relief valve V3, which is a differential pressure valve, is arranged in the middle of the relief channel C3. The relief valve is not opened and closed by a drive mechanism but is spring-biased and configured to open when a predetermined pressure is reached. For example, assume that the ink supply amount per unit time supplied from the supply pump P1 to the IN channel 80b is greater than the total value of the discharge amount per unit time of the recording head 8 and the ink flow rate per unit time flowing from the recovery pump P2 to the recovery channel C4. In this case, the relief valve V3 is opened according to the pressure acting on itself. As a result, a circulation channel composed of a part of the supply channel C2 and the relief channel C3 is formed. By providing the configuration of the relief channel C3, the ink supply amount to the recording head 8 can be adjusted according to the ink consumption amount at the recording head 8, and the pressure in the circulation channel can be stabilized regardless of the image data.

[0053] The recovery channel C4 is a channel for recovering ink from the recording head 8 to the sub-tank 151, and a recovery pump P2 and a recovery valve V4 are arranged in the middle thereof. The recovery pump P2 serves as a negative pressure generation source to suck ink from the recording head 8 when circulating ink in the circulation path. By driving the recovery pump P2, an appropriate pressure difference is generated between the IN channel 80b and the OUT channel 80c in the recording head 8, and ink can be circulated between the IN channel 80b and the OUT channel 80c.

[0054] The recovery valve V4 is also a valve for preventing backflow when the recording operation is not being performed, that is, when ink is not being circulated in the circulation path. In the circulation path of the present embodiment, the sub-tank 151 is arranged above the recording head 8 in the vertical direction (see FIG. 1). Therefore, when the supply pump P1 and the recovery pump P2 are not being driven, there is a risk that ink will flow back from the sub-tank 151 to the recording head 8 due to the head difference between the sub-tank 151 and the recording head 8. To prevent such backflow, the recovery valve V4 is provided in the recovery channel C4 in the present embodiment.

[0055] Note that the supply valve V2 also functions as a valve for preventing the supply of ink from the sub-tank 151 to the recording head 8 when the recording operation is not being performed, that is, when the ink is not being circulated in the circulation path.

[0056] The head replacement flow path C5 is a flow path that connects the supply flow path C2 and the air chamber (space where ink is not stored) of the sub-tank 151. A head replacement valve V5 is arranged in the middle of the head replacement flow path C5. One end of the head replacement flow path C5 is connected upstream of the recording head 8 in the supply flow path C2 and downstream of the supply valve V2. The other end of the head replacement flow path C5 is connected above the sub-tank 151 and communicates with the air chamber inside the sub-tank 151. The head replacement flow path C5 is used when withdrawing ink from the recording head 8 in use, such as when replacing the recording head 8 or transporting the recording apparatus 1. The head replacement valve V5 is controlled by the ink supply control unit 209 so as to be closed except when filling the recording head 8 with ink and when recovering ink from the recording head 8.

[0057] Next, the flow path configuration inside the recording head 8 will be described. The ink supplied to the recording head 8 from the supply flow path C2 passes through the filter 83 and is then supplied to the first negative pressure control unit 81 and the second negative pressure control unit 82. The control pressure of the first negative pressure control unit 81 is set to a negative pressure as weak as, for example, -90 mmAq (a negative pressure with a small pressure difference from the atmospheric pressure). The control pressure of the second negative pressure control unit 82 is set to a negative pressure as strong as -180 mmAq (a negative pressure with a large pressure difference from the atmospheric pressure). The pressures in these first negative pressure control unit 81 and second negative pressure control unit 82 are generated within an appropriate range by driving the recovery pump P2.

[0058] The ink ejection unit 80 is provided with a plurality of recording element substrates 80a on which a plurality of ejection ports are arranged, forming a long ejection port row. A common supply channel 80b (IN channel) for guiding the ink supplied from the first negative pressure control unit 81 and a common recovery channel 80c (OUT channel) for guiding the ink supplied from the second negative pressure control unit 82 also extend in the arrangement direction of the recording element substrates 80a. Further, individual supply channels connected to the common supply channel 80b and individual recovery channels connected to the common recovery channel 80c are formed on each of the individual recording element substrates 80a. For this reason, in each of the individual recording element substrates 80a, an ink flow is generated such that the ink flows in from the common supply channel 80b with relatively weak negative pressure and flows out to the common recovery channel 80c with relatively strong negative pressure. Pressure chambers that communicate with each ejection port and are filled with ink are provided in the paths of the individual supply channels and the individual recovery channels, and an ink flow also occurs in the ejection ports and pressure chambers where recording is not being performed. When the ejection operation is performed on the recording element substrate 80a, a part of the ink that moves from the common supply channel 80b to the common recovery channel 80c is consumed by being ejected from the ejection ports, but the ink that is not ejected moves to the recovery channel C4 through the common recovery channel 80c.

[0059] FIG. 8(a) is an enlarged plan schematic view of a part of the recording element substrate 80a, and FIG. 8(b) is a cross-sectional schematic view taken along the section line VIIIb-VIIIb of FIG. 8(a). The recording element substrate 80a is provided with a pressure chamber 85 filled with ink and an ejection port 86 for ejecting the ink. In the pressure chamber 85, a recording element 84 is provided at a position facing the ejection port 86. Further, a plurality of individual supply channels 88 connected to the common supply channel 80b and a plurality of individual recovery channels 89 connected to the common recovery channel 80c are formed for each ejection port 86 on the recording element substrate 80a.

[0060] With the above configuration, in the recording element substrate 80a, ink flows in from the common supply channel 80b with relatively weak negative pressure and flows out to the common recovery channel 80c with relatively strong negative pressure. More specifically, the ink flows in the order of common supply channel 80b → individual supply channel 88 → pressure chamber 85 → individual recovery channel 89 → common recovery channel 80c. When the ink is ejected by the recording element 84, a part of the ink moving from the common supply channel 80b to the common recovery channel 80c is ejected from the ejection port 86 and discharged to the outside of the recording head 8. On the other hand, the ink that has not been ejected from the ejection port 86 is recovered to the recovery channel C4 through the common recovery channel 80c.

[0061] Under the above configuration, when performing the recording operation, the ink supply control unit 209 closes the tank supply valve V1 and the head replacement valve V5, opens the atmosphere release valve V0, the supply valve V2, and the recovery valve V4, and drives the supply pump P1 and the recovery pump P2. Thereby, a circulation path of sub-tank 151 → supply channel C2 → recording head 8 → recovery channel C4 → sub-tank 151 is established. When the ink supply amount per unit time from the supply pump P1 is larger than the total value of the ejection amount per unit time of the recording head 8 and the flow rate per unit time in the recovery pump P2, the ink flows from the supply channel C2 into the relief channel C3. Thereby, the flow rate of the ink flowing into the recording head 8 from the supply channel C2 is adjusted.

[0062] When not performing the recording operation, the ink supply control unit 209 stops the supply pump P1 and the recovery pump P2 and closes the atmosphere release valve V0, the supply valve V2, and the recovery valve V4. Thereby, the flow of the ink in the recording head 8 stops, and the backflow due to the water head difference between the sub-tank 151 and the recording head 8 is also suppressed. Also, by closing the atmosphere release valve V0, the ink leakage from the sub-tank 151 and the evaporation of the ink are suppressed.

[0063] When recovering ink from the recording head 8, the ink supply control unit 209 closes the atmosphere release valve V0, the tank supply valve V1, the supply valve V2, and the recovery valve V4, opens the head replacement valve V5, and drives the decompression pump P0. As a result, the inside of the sub-tank 151 becomes a negative pressure state, and the ink in the recording head 8 is recovered into the sub-tank 151 via the head replacement flow path C5. In this way, the head replacement valve V5 is closed during normal recording operations and standby, and is a valve that is opened when recovering ink from the recording head 8. Note that the head replacement valve V5 is also opened when filling the head replacement flow path C5 with ink during filling of the recording head 8.

[0064] In the circulation flow path of the present embodiment, ink flows through the flow path passing through the pressure chamber 85, but a flow path that does not pass through the pressure chamber 85 may also be used. For example, a form in which ink flows in the order of the supply and recovery flow path 80b → the recovery flow path 4c may be used.

[0065] (Detection process of ink ejection state) In the present embodiment, the temperature detection element 91 provided on the recording element substrate 80a of the recording head 8 is used to detect the ejection state of the ink.

[0066] FIG. 9(a) is a diagram showing a recording element 84 and a temperature detection element 91 provided corresponding to a discharge port 86 in a recording element substrate 80a. FIG. 9(b) is a cross-sectional view taken along line IXb-IXb in FIG. 9(a), and FIG. 9(c) is a cross-sectional view taken along line IXc-IXc in FIG. 9(a). The recording element 84 is a discharge energy generating element that generates discharge energy for discharging ink. The recording element 84 in this example is an electrothermal conversion element (heating resistor element) made of a tantalum silicon nitride film or the like, and is connected to a wiring 93 of the recording element substrate 80a by a conductive plug 92 made of tungsten or the like. When a drive pulse is applied to this recording element 84 to generate heat, the ink in the pressure chamber 85 is foamed. Using the foaming energy, the ink in the pressure chamber 85 is discharged from the discharge port 86. The temperature detection element 91 in this example is a thin film resistor made of a titanium and titanium nitride laminated film or the like, and is connected to the wiring 93 by a conductive plug 98 made of tungsten or the like. An interlayer insulating film 94, a protective film 95, and an anti-cavitation film 96 are formed on the recording element substrate 80a. Further, a discharge port forming member 97 for forming the discharge port 86 is provided on the recording element substrate 80a.

[0067] The temperature of the recording element 84 mounted on the recording element substrate 80a is detected using the print controller 202, the head I / F 206 connected to the recording head 8, and the RAM 204. The head I / F 206 includes a signal generation unit that generates various signals for transmission to the recording element substrate 80a, and a determination result extraction unit that inputs a determination result signal RSLT output from the recording element substrate 80a based on the temperature information detected by the temperature detection element 91. For temperature detection, when the print controller 202 issues an instruction to the signal generation unit, the signal generation unit outputs a signal to the recording element substrate 80a. The signal includes a clock signal CLK, a latch signal LT, a block signal BLE, a recording data signal DATA, a heat enable signal HE, and a discharge inspection threshold signal Ddth. The discharge inspection threshold signal Ddth can set a threshold for a recording element group obtained by dividing a plurality of recording elements mounted on the recording head 8 into a plurality of groups each consisting of a plurality of recording elements located in the vicinity of each other, and is configured to be able to change the set value in one column cycle. A configuration will be described in which the discharge inspection threshold voltage (Th) can be set for each group.

[0068] FIG. 10 is an explanatory diagram of the detected temperature of the temperature detection element 91 when a drive pulse P is applied to the recording element 84. When the drive pulse P in FIG. 10(a) is applied, the recording element 84 generates heat, and ink is discharged from the discharge port 86 by the foaming energy of the ink. The detected temperature of the temperature detection element 91 changes like the solid line curve La in FIG. 10(b) when the ink is discharged normally, and changes like the dotted line curve Lb in FIG. 10(b) when a discharge defect of the ink occurs. When the ink is discharged normally, a part of the ink droplets discharged from the discharge port 86 falls on the upper part of the recording element 84 and cools the recording element 84. As a result, as in the curve La, the temperature in the vicinity of the recording element 84 rapidly decreases, and thus the detected temperature of the temperature detection element 91 also rapidly decreases. On the other hand, when a discharge defect of the ink occurs, since cooling due to the fall of a part of such ink droplets does not occur, the detected temperature of the temperature detection element 91 gradually decreases as in the curve Lb.

[0069] FIG. 10(c) is an explanatory diagram of temperature change values obtained by differentiating the temperature changes of curves La and Lb, and compares the temperature change value at the timing set by the detection timing signal S in FIG. 10(a) with a predetermined threshold value Th. In FIG. 10(c), the temperature change value indicated by the solid curve LA is the differential value of curve La, and the temperature change value indicated by the dotted curve LB is the differential value of curve Lb. At the timing set by the detection timing signal S, the temperature change value of curve LA exceeds the threshold value Th, and the temperature change value of curve LB does not exceed the threshold value Th. When the threshold value Th is exceeded as in curve LA, it appears that the threshold value has been exceeded in the determination result signal RSLT from the recording element substrate 80a. This signal is input to the determination result extraction unit and stored in the RAM 204. As described above, the ejection state of the ink can be detected based on whether or not the differential value of the detected temperature of the temperature detection element 91 exceeds the threshold value Th.

[0070] Also, the ejection state of the ink can be detected by the following method. While ejecting ink from all the ejection ports of the recording head 8, the flying ink immediately after ejection is optically scanned with a device that optically detects the ejected ink. In this method, an optical scanning unit having a light emitting unit and a light receiving unit is used. The optical scanning unit is scanned so that the optical axis formed between the light emitting unit and the light receiving unit passes through the flight path of the ejected ink. When ink is ejected, the light from the light emitting unit is blocked and the light reception amount of the light receiving unit decreases. By detecting this phenomenon of the light reception amount, the ejection state of the ink can be detected.

[0071] (Ink circulation process) In the present embodiment, as described above, the ink is circulated through the pressure chamber of the recording head 8. By such ink circulation, the ejection state of the ink in the recording head 8 can be restored. For example, when ink ejection failure occurs due to thickening of the ink near the ejection port caused by evaporation of moisture in the ink, the ink ejection state can be restored to a normal state. Therefore, the circulation operation for circulating the ink is one of the restoration operations for maintaining the ink ejection state in the recording head 8 well.

[0072] FIG. 11 is a flowchart for explaining the ink circulation process performed as a recovery process, in which the ink circulation operation and the detection operation in the detection process of the ink ejection state are executed in parallel. This can shorten the total time required for the recovery process and the detection process.

[0073] The circulation process is a process performed when the power of the recording device is turned on or when a print instruction is input. In this embodiment, it is performed when a print instruction is input. When a print job is input from the host device 400 or a print instruction is input from the operation panel 104 to the main controller 101, the main controller 101 instructs the print controller 202 to perform the circulation process. Upon receiving the instruction, the print controller 202 controls the ink supply control unit 209 and the recording head 8 via the head I / F 206, and the circulation process is performed. In addition, when performing the circulation process periodically at predetermined timings, or in the case of a circulation process in the event of an error, a maintenance instruction from the user, etc., the method of the following embodiment can also be applied.

[0074] In the example shown with reference to FIG. 11, in order to determine the end timing of the circulation process, the detection result of the detection process of the ink ejection state described above is used. The ink circulation process in FIG. 11 is executed under the control of the main controller 101 of the controller unit 100 or the print controller 202 of the print engine unit 200. When the main controller 101 receives a print instruction, in the print engine unit 200, the print controller 202 determines to perform the following circulation process (1) or (2) as a preparation for printing. Thereby, it is determined to start the ink circulation operation. Also, along with the execution of this circulation operation, it is also determined to perform a detection process involving the ink ejection operation described later. The symbol "S" in FIG. 11 means a step in a series of processes.

[0075] In the ink circulation process (1) of Fig. 11(a), after starting the ink circulation operation (S1), a detection process involving the above-described ink ejection operation is performed (S2). Based on the detection result, as described later, it is determined whether the ink ejection state in the recording head is good (S3). Once the detection process ends in this determination, if it is not determined to be good, the process returns to (S2). Although the details of the determination will be described later, as a basic concept, for example, when the number of non-ejecting nozzles is less than or equal to a first number determined by a predetermined condition, the ejection state is good, while when the number of non-ejecting nozzles is more than the first number, the ejection state is bad. By repeatedly performing the determination multiple times as the detection process is repeated, the ink circulation operation is continued until it is determined that the ink ejection state in the recording head is good. Then, when it is determined that the ink ejection state in the recording head is good, the ink circulation operation is terminated (S4), and the ink circulation process (1) is terminated.

[0076] In the ink circulation process (2) of Fig. 11(b), similar to the circulation process (1), based on the detection result of the detection process of the ink ejection state in the recording head, it is determined whether the ink ejection state is good as described later (S3). The ink circulation operation is continued until it is determined that the ink ejection state in the recording head is good, and when it is determined that the ejection state is good, it is determined whether there is a next operation involving ink circulation (S5). If there is no next operation involving ink circulation, the ink circulation operation is terminated (S4), and the ink circulation process (2) is terminated. If there is a next operation involving ink circulation, the process of Fig. 11(b) is terminated, and the process proceeds to the process for executing the next operation involving ink circulation. At this time, the ink circulation continues. In this embodiment, the next operation involving ink circulation includes the recording operation. That is, in parallel with the ink circulation performed at the previous stage of the recording operation, for example, the preparation stage, a detection process of the ink ejection state is performed, and while continuing the ink circulation, the process proceeds to the recording operation.

[0077] (Method for Determining the Ink Ejection State in the Recording Head) In S3 of FIGS. 11(a) and (b), as a method for determining whether the ink ejection state of the recording head is good, for example, the following first, second, and third determination methods can be adopted.

[0078] (First determination method) In the first determination method, based on the number of ejection ports where ink non-ejection has occurred, it is determined whether the ink ejection state of the entire recording head 8 is good. For example, assume a recording head 8 that includes 15 chips corresponding to the recording element substrate 80a connected in series, and each chip has 1024 nozzles capable of ejecting 5 colors of ink for each ink color. The 5 colors of ink are black (K1, K2), cyan (C), magenta (M), and yellow (Y) inks. The nozzles include recording elements 84, pressure chambers 85, ejection ports 86, and the like. The total number of nozzles in such a recording head is 76,800 (5×1024×15).

[0079] As shown in FIG. 12(a), for each ink color, a threshold value for the number of nozzles where ink non-ejection has occurred (non-ejection nozzles) is set. Then, for each ink color, the number of detected non-ejection nozzles is compared with the corresponding threshold value. When, for all ink colors, all of the detected numbers of non-ejection nozzles are less than or equal to the corresponding threshold values, it is determined that the entire recording head is in a good ejection state. When, for at least one ink color, the number of detected non-ejection nozzles exceeds the corresponding threshold value, it is determined that the ejection state of the entire recording head is poor. Since black ink is likely to be noticeable when nozzle non-ejection occurs, the threshold value for black ink is set to a relatively small value. Also, since yellow ink is less likely to be noticeable when nozzle non-ejection occurs, the threshold value for yellow ink is set to a relatively large value.

[0080] Also, a threshold value for the total of all ink colors is set separately from each ink color. Even if each ink color is below the threshold value, when the total number of non-ejection nozzles for all ink colors exceeds the threshold value, it is determined that the ejection state is poor.

[0081] Also, as shown in FIG. 12(b), for each ink color, the ratio of the number of non-ejecting nozzles to the total number of nozzles may be set as a threshold value. In this case, for all ink colors, when all of the ratios of the number of detected non-ejecting nozzles are equal to or less than the corresponding threshold values, it is determined that the entire recording head is in a good ejection state. When the ratio of the number of detected non-ejecting nozzles exceeds the corresponding threshold value for at least one ink color or for the total of all ink colors, it is determined that the ejection state of the entire recording head is poor.

[0082] (Second determination method) In the second determination method, based on the number of non-ejecting nozzles in units of chips in the recording head 8, it is determined whether the ink ejection state of the entire recording head 8 is normal. Similar to the case of the first determination method described above, assume that the recording head 8 includes 15 chips corresponding to the recording element substrate 80a connected in series, and for each individual chip, 1024 nozzles capable of ejecting five colors of ink are formed for each ink color.

[0083] As shown in FIG. 13(a), for each of the 15 chips from the 0th to the 14th, threshold values for the total number of non-ejecting nozzles generated in each nozzle of the five colors of ink are set. Then, for each chip, the total number of detected non-ejecting nozzles for each of the five colors of ink is compared with the corresponding threshold value. When, for all chips, all of the total numbers of detected non-ejecting nozzles are equal to or less than the corresponding threshold values, it is determined that the entire recording head is in a good ejection state. When, for at least one chip, the total number of detected non-ejecting nozzles exceeds the corresponding threshold value, it is determined that the ejection state of the entire recording head is poor. Since the change in the recorded image when non-ejection of nozzles occurs is likely to be prominent for the chip located in the center, the threshold value for the chip located in the center is set to a relatively small value. Also, since the change in the recorded image when non-ejection of nozzles occurs is less likely to be prominent for the chips located on both sides, the threshold values for the chips located on both sides are set to relatively large values.

[0084] Also, as shown in FIG. 13(b), a threshold value may be set for each ink color in each chip. When, for all chips, all of the numbers of non-ejecting nozzles detected for each ink color are equal to or less than the threshold value for the corresponding ink color, it is determined that the entire recording head is in a good ejection state. When, in at least one chip, at least one of the numbers of non-ejecting nozzles detected for each ink color exceeds the corresponding threshold value, it is determined that the ejection state of the entire recording head is poor.

[0085] (Third determination method) In the third determination method, the nozzles pre-stored as non-ejecting nozzles are excluded, and based on the number of newly detected non-ejecting nozzles, it is determined whether the ink ejection state of the entire recording head 8 is normal.

[0086] The main factors causing the non-ejection state of ink that can be recovered by the ink circulation operation mainly include the adhesion of thickened ink to the ejection port or the like. However, for the nozzles determined as non-ejecting nozzles in the previous detection process (non-ejection determination nozzles), for example, due to factors such as nozzle failure or blockage of the ejection port by foreign matter such as dust, there is a possibility that they cannot be recovered by the ink circulation operation. In the third determination method, such non-recoverable non-ejection determination nozzles are pre-stored, and such non-ejection determination nozzles are excluded from the determination target of the quality of the ink ejection state of the entire recording head. Thereby, the time during which the recording apparatus cannot perform recording due to the ink circulation process can be suppressed. The controller unit 100 or the print engine unit 200 has a function for storing non-recoverable non-ejection determination nozzles in the ROM 107 by the ink circulation operation.

[0087] FIG. 14 is a diagram for explaining a specific example of the third determination method. For the sake of convenience in explanation, the number of nozzles for each ink color is assumed to be 10 (nozzle numbers 0 to 9). Also, as a threshold value for each ink color, 15% of the ratio of the number of non-ejecting nozzles to the total number of nozzles is set. Regarding the nozzles for black ink K1, there is 1 non-ejecting determination nozzle, and the number of non-ejecting nozzles detected this time is 2 including the non-ejecting determination nozzle. Therefore, the number of nozzles to be determined is "9" obtained by excluding the number of non-ejecting determination nozzles "1" from the total number of nozzles "10", and the number of detected non-ejecting nozzles is "1". As a result, the ratio of non-ejecting nozzles is 11%, which is less than or equal to 15% of the threshold value. Therefore, regarding the nozzles for black ink K1, the ink ejection state is determined to be good "OK".

[0088] Also, regarding the nozzles for black ink K2, there is 1 non-ejecting determination nozzle, and the number of non-ejecting nozzles detected this time is 2 without including the non-ejecting determination nozzle. Therefore, the number of nozzles to be determined is "9", and the number of detected non-ejecting nozzles is "2". As a result, the ratio of non-ejecting nozzles is 22%, which exceeds 15% of the threshold value. Therefore, regarding the nozzles for black ink K2, the ink ejection state is determined to be bad "NG". Regarding inks C, M, and Y, the ink ejection state is determined to be good "OK".

[0089] In the case of FIG. 14, since the ink ejection state of the nozzles for black ink K2 is determined to be bad "NG", the ejection state of the entire recording head is determined to be bad.

[0090] (Second Embodiment) In this embodiment, after making the atmosphere around the ejection port of the recording head 8 in a wet state, an ink circulation process is performed.

[0091] FIG. 15 is a flowchart for explaining the ink circulation process in the present embodiment. For the same steps as those in FIG. 11 described above, the same symbols are used and the description thereof is omitted. In the present embodiment, before the start (S1) of the ink circulation process, preliminary discharge is performed (S10) to make the atmosphere around the discharge port of the recording head 8 moist inside the cap member 10a that can be in close contact with the discharge port surface 8a of the recording head 8. That is, ink is discharged into the cap member 10a of the cap unit 10 to humidify the inside of the cap member 10a, and then the cap member 10a is brought into close contact (capping) with the discharge port surface 8a of the recording head 8. In this way, by using the capping-capable cap member 10a, the atmosphere around the discharge port is humidified, making it easier to eliminate the sticking of thickened ink at the discharge port. As a result, the effect of restoring the discharge state of the recording head by the ink circulation operation can be further enhanced.

[0092] In the preliminary discharge for wetting (S10), it is desirable to discharge color inks (C, M, Y) that are relatively less likely to adhere than black ink (K). The reason is to reduce the risk of poor discharge of the wetting ink due to the ink that adheres easily. Also, the series of ink circulation processes in FIG. 15 can be carried out in a state where the cap member 10a is in close contact with the discharge port surface 8a of the recording head 8 (cap closed state). Thereby, ink can be applied to the sealed space inside the cap member 10a in the cap closed state by the preliminary discharge for wetting, and the humidifying effect of the atmosphere around the discharge port can be enhanced. Further, with the cap member 10a separated from the discharge port surface 8a of the recording head 8 (cap open state), ink can be applied to the inside of the cap member 10a by the preliminary discharge for wetting, and the series of ink circulation processes in FIG. 15 may be carried out while the cap is in the open state. In this case, when the ink discharged in the preliminary discharge for wetting (S10) and the inspection process (S2) is discharged, the risk that the ink bounces back from the inside of the cap member 10a and adheres to the discharge port surface 8a can be reduced. Even in the case of the cap open state, the atmospheric humidifying effect by the preliminary discharge for wetting reaches the peripheral space including above the cap. Also, after the preliminary discharge for wetting, the cap may be closed.

[0093] (Third Embodiment) In this embodiment, the timing for carrying out the detection process of the ink discharge state is set.

[0094] FIG. 16 is a flowchart for explaining the ink circulation process in the present embodiment. For the same steps as those in FIG. 11 described above, the same symbols are used and the description is omitted. In the present embodiment, when it is determined that the ink ejection state is defective by the ink ejection state detection process (S2), the process proceeds from S3 to S20, and it is determined whether or not the elapsed time since the detection process (S2) was performed is equal to or longer than a predetermined time T1. When the elapsed time becomes equal to or longer than the time T1, the detection process (S2) is performed again. The time T1 can be set according to various conditions. For example, when it is necessary to promptly execute the next operation after the ink circulation process in FIG. 16, the time T1 is set relatively short. Thereby, by repeatedly performing the detection process (S2) involving ink ejection in a short period of time and frequently detecting the recovery state of the ink ejection state, the next operation can be executed immediately when the recovery is completed. Also, when it is assumed that the degree of adhesion of the thickened ink around the ejection port and the like is low and the amount of ink adhering to the ejection port surface 8a is small, the time T1 is set relatively short. On the other hand, when it is assumed that the degree of adhesion of the thickened ink around the ejection port and the like is high and the amount of ink adhering to the ejection port surface 8a is large, the time T1 is set relatively long. Thereby, it is possible to suppress the consumption of the ink ejected along with the detection process (S2) and the power consumption associated with the detection process (S2).

[0095] (Fourth Embodiment) In the present embodiment, the timing of performing the ink ejection state detection process is set based on the start time of the ink circulation process.

[0096] FIG. 17 is a flowchart for explaining the ink circulation process in the present embodiment. For steps similar to those in FIG. 11 described above, the same symbols are used and the explanations are omitted. In the present embodiment, when it is determined that the ink ejection state is defective by the ink ejection state detection process (S2), the process proceeds from S3 to S30, and it is determined whether the elapsed time since the start of the ink circulation operation (S1) is equal to or longer than a predetermined time T2. When the elapsed time is equal to or shorter than the time T2, the detection process (S2) is performed again. When the elapsed time becomes equal to or longer than the time T2, the series of circulation processes in FIG. 17 is terminated. That is, when it is not determined that the ink ejection state is good within a predetermined time, the series of circulation processes in FIG. 17 is terminated. In this way, by setting an upper limit on the time of the ink circulation process, even if there is a non-ejecting nozzle that cannot be recovered due to, for example, a heater failure during the ink circulation operation, the series of circulation processes in FIG. 17 can be terminated.

[0097] (Fifth Embodiment) In the present embodiment, even if it is determined that the ink ejection state is good, the ink ejection state detection process is repeated a predetermined number of times.

[0098] FIG. 18 is a flowchart for explaining the ink circulation process in the present embodiment. For steps similar to those in FIG. 11 described above, the same symbols are used and the explanations are omitted. In the present embodiment, when it is determined that the ink ejection state is good by the ink ejection state detection process (S2), the process proceeds from S3 to S41, and “1” is added to the count value C. The count value C is reset to “0” before the detection process (S2) is performed. The count value C is compared with a predetermined threshold value Cth (S42), the detection process (S2) is repeated until the count value C reaches the threshold value Nth, and when the count value C reaches the threshold value Cth, the series of circulation processes in FIG. 17 is terminated.

[0099] For example, even if the thickened ink around the ejection port cannot be completely removed by the ink circulation operation, ink may still be ejected, and it may be determined that the ink ejection state is good in the detection process. In this case, even a slight progress in the thickening of the ink before the next recording operation may cause the ink ejection state to become poor. In the present embodiment, even if it is determined that the ink ejection state is good, by repeating the detection process of the ink ejection state a predetermined number of times or more, the ink ejection state can be more reliably restored.

[0100] (Sixth Embodiment) In the present embodiment, the detection process of the ink ejection state is performed only for a specific ink.

[0101] FIG. 19(a) is a flowchart for explaining the ink circulation process in the present embodiment. First, after starting the circulation operation for circulating all-color ink (S51), the detection process involving the above-described ink ejection operation is performed only for black ink (S52), and based on the detection result, it is determined whether the ejection state of the black ink is good (S53). For example, when the ratio of the number of non-ejecting nozzles to the total number of nozzles for black ink is 0.4% or less, it is determined that the ink ejection state of the entire recording head is good. In this way, the circulation operation of all-color ink is continued until it is determined that the ejection state of the black ink is good, and when it is determined that the ejection state of the black ink is good, the circulation operation of all-color ink is terminated (S54).

[0102] FIG. 19(b) shows an example of the transition of the number of non-ejecting nozzles for each ink color during the execution of the ink circulation operation. As is clear from this figure, since black ink (K1, K2) is more likely to thicken when exposed to the atmosphere compared to color inks (C, M, Y), the time required to recover non-ejecting nozzles to a good ejection state is often longer for black ink than for color ink. Therefore, by performing the ink circulation operation until non-ejecting nozzles for black ink are determined to be in a good ejection state, non-ejecting nozzles for color ink are highly likely to be in a good ejection state. From such a perspective, in the present embodiment, the target of the circulation operation is all-color inks, and the target of the ejection state detection process is only black ink. Thereby, the amount of ink ejected and the power consumption in the ejection state detection process can be suppressed. Thus, among a plurality of types of inks having different viscosities, an ink having a relatively high viscosity and being likely to stick, for example, black ink, is made the target of the ejection state detection process.

[0103] Also, the target of the circulation operation may be all nozzles in the recording head, and the target of the ejection state detection process may be only specific nozzles. That is, the target of the ejection state detection process may be specified in nozzle units. As the target of the detection process, it is preferable to select nozzles where ink sticking is likely to progress. Also, when the degree of ink sticking progress is substantially equal for all nozzles of the recording head, the target of the detection process does not necessarily have to be all nozzles, and may be limited to some representative nozzles obtained by thinning out all nozzles. Thus, by limiting the nozzles that are the target of the detection process, the amount of ink ejected and the power consumption in the ejection state detection process can be suppressed.

[0104] Also, in the present embodiment, the target of the circulation operation is all-color inks. However, for example, in a configuration where the circulation operation for each color ink can be individually controlled, the ink circulation operation as shown in FIG. 19(a) may be individually performed for each color ink.

[0105] (Other Embodiments) When the time of the recording operation exceeds a predetermined time (for example, 25 seconds), before the next recording operation, the ink circulation process in each of the above-described embodiments may be executed. Further, a mechanism for detecting or predicting the temperature of the recording head during the recording operation is provided, and when the temperature of the recording head during the recording operation exceeds a predetermined temperature (for example, 45°C), before the next recording operation, the ink circulation process in each of the above-described embodiments may be executed. This is because due to the head temperature rise and heat accumulation during the recording operation, moisture evaporation from the nozzles is more likely to proceed than usual even after the recording operation is completed, and a state in which ejection failure is likely to occur.

[0106] Also, when the off time of the power supply of the recording apparatus exceeds a predetermined time (for example, 64 hours), before the next power-on, the ink circulation process in each of the above-described embodiments may be executed. Further, when the non-circulation time during which the ink is not circulated exceeds a predetermined time, before the next recording operation, the ink circulation process in each of the above-described embodiments may be executed.

[0107] The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and causing one or more processors in a computer of the system or apparatus to read and execute the program. Further, it can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Explanation of Reference Numerals

[0108] 1 Inkjet recording apparatus 8 Recording head 84 Recording element (ejection energy generation element) 85 Pressure chamber 86 Ejection port 91 Temperature detection element 101 Main controller 202 Print controller

Claims

1. a recording head having an ejection port for ejecting ink, an energy generating element provided in correspondence with the ejection port for generating energy used to eject the ink, and a pressure chamber located opposite the energy generating element; a detection means for performing a detection operation to detect an ink ejection state of the ejection port; a circulation means for circulating ink through the pressure chamber; a control means for causing the circulating means to perform an ink circulating operation and the detecting means to perform a detecting operation in parallel; having The control means, when completing the detection operation, stops the circulation of ink by the circulation means if the next operation to be executed does not involve the circulation of ink, and continues circulating ink by the circulation means even after the detection operation is stopped if the next operation involves the circulation of ink.

2. 2. The inkjet recording apparatus according to claim 1, wherein the next operation includes an operation of recording an image by using ink ejected from the recording head.

3. The inkjet recording apparatus according to claim 1 or 2, characterized in that, based on the detection result of the detection means, if the number of non-ejecting orifices is a first number, the control means causes the detection means to end the detection operation, and if the number of the non-ejecting orifices is greater than the first number, the control means causes the detection means to continue the detection operation.

4. The inkjet recording device according to claim 3, characterized in that the control means, based on the detection result of the detection means, causes the circulation means to stop circulating the ink when the number of non-ejecting orifices is the first number, and causes the circulation means to continue circulating the ink when the number of the non-ejecting orifices is greater than the first number.

5. 5. The ink jet recording apparatus according to claim 3, wherein the control means does not cause the circulation means to stop circulating the ink until the detection means has completed the detection operation.

6. An inkjet recording device as described in any one of claims 3 to 5, characterized in that when the number of the non-ejecting outlets is the first number, the control means stops the circulation of ink in the circulation means when the next operation to be performed by the inkjet recording device does not involve circulation of ink, and does not stop the circulation of ink in the circulation means when the next operation involves circulation of ink.

7. An inkjet recording device as described in any one of claims 3 to 6, characterized in that when the number of the non-ejecting outlets is greater than the first number, the control means waits for a first predetermined time to elapse before executing the detection operation, and does not cause the circulation means to stop circulating ink until the detection means has completed the detection operation.

8. An inkjet recording apparatus according to any one of claims 3 to 7, characterized in that the control means causes the detection means to terminate the detection operation if the number of the non-ejecting orifices does not become equal to or less than the first number within a second predetermined time from the start of the detection operation.

9. The inkjet recording apparatus according to any one of claims 3 to 8, characterized in that the control means causes the detection means to perform the detection operation multiple times, and when the determination means determines multiple times that the number of the non-ejecting outlets is less than a predetermined number, causes the detection means to terminate the detection operation.

10. a flow path for supplying ink from an ink tank that stores ink to the recording head; 10. The ink jet recording apparatus according to claim 1, wherein the circulating means circulates the ink through at least a part of the flow path and the pressure chamber.

11. a cap capable of sealingly covering the ejection port of the recording head; The inkjet recording apparatus according to any one of claims 1 to 10, wherein the control means causes the circulation means to circulate the ink in a state in which the cap and the ejection port are in close contact with each other after ink has been ejected from the ejection port into the cap.

12. the recording head is capable of ejecting a plurality of types of ink, the control means causes the circulation means to circulate the ink through the flow paths of the plurality of types of ink; 12. The inkjet recording apparatus according to claim 1, wherein the detection unit executes the detection operation for a specific ink among the plurality of types of ink.

13. the plurality of types of ink include inks having different viscosities, which are the degree of viscosity increase caused by evaporation of water in the ink; 13. The inkjet recording apparatus according to claim 12, wherein the specific ink has a relatively high viscosity.

14. the recording head is capable of ejecting ink from a plurality of ejection ports; the circulation means circulates ink through the flow paths of the plurality of ejection ports; 14. The inkjet recording apparatus according to claim 1, wherein the detection unit causes the circulation unit to circulate the ink, and causes the detection unit to execute the detection operation for a discharge port selected from the plurality of discharge ports.

15. the print head has electrothermal transducers that generate ejection energy for ejecting ink from the ejection ports; 15. The ink jet recording apparatus according to claim 1, wherein the detection means has a temperature detection element for detecting a temperature of the electrothermal conversion element.

16. 16. The inkjet printing apparatus according to claim 15, wherein the detection means detects the ink ejection state in the print head based on a temperature change in the electrothermal conversion element detected by the temperature detection element when ink is ejected from the ejection port.

17. An inkjet recording method for recording an image using a recording head having: an ejection port for ejecting ink; an energy generating element provided in correspondence with the ejection port, the energy generating element generating energy used for ejecting the ink; and a pressure chamber located opposite the energy generating element, the method comprising: a detection step of detecting an ink ejection state of the ejection port; a circulating step of circulating the ink through the pressure chamber; a control step of causing the circulation of ink by the circulation step and the detection operation by the detection step to be performed in parallel; Including, an inkjet recording method characterized in that, in the control step, when the detection step is terminated, if the next operation to be executed does not involve the circulation of ink, the circulation of ink in the circulation step is stopped, and if the next operation involves the circulation of ink, the circulation of ink in the circulation step is continued even after the detection step is stopped.

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