Recording device, control method, and program

Abstract

To make a recording head discharge liquid, while reducing waste ink.SOLUTION: A recording device includes: supply means for supplying liquid; a circulation path having a flow channel for circulating the liquid so that the liquid entering a recording head is discharged from the recording head and then enters the recording head, and a branch flow channel branched from the flow channel on the downstream of the supply means provided on the flow channel and circulating the liquid so as to send the liquid to the upstream of the supply means without through a tank storing the liquid, wherein the liquid supplied to the recording head from the supply means through the branch flow channel is sent to the recording head from the supply means without through a tank storing the liquid; acquisition means for acquiring information on a temperature; and means for changing a time during which the liquid of the circulation path is circulated by the supply means, on the basis of the information acquired by the acquisition means.SELECTED DRAWING: Figure 12

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a printer that forcibly discharges an amount of ink corresponding to the effective water content in the ink to eliminate nozzle clogging.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1, ink is discharged to eliminate clogging, and there is a problem that waste ink is generated.

[0005] Therefore, in view of the above problems, an object of the present invention is to make the recording head capable of discharging a liquid such as ink while reducing waste ink.

Means for Solving the Problems

[0006] The present invention is a recording apparatus having a tank for storing a liquid, a recording head having a discharge port surface provided with a discharge port for discharging the liquid supplied from the tank, a cap mechanism for capping the discharge port surface, a timer for counting the time during which the discharge port surface is capped, and a circulation means for circulating the liquid in a circulation path including the tank and the recording head, wherein when the timer counts a predetermined time, the circulation means circulates the liquid.

Effects of the Invention

[0007] According to the present invention, it is possible to reduce waste ink and keep the recording head in a state where liquid can be ejected.

Brief Description of the Drawings

[0008]

Figure 1

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Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the drawings, a liquid ejection head and a liquid ejection device according to embodiments of the present invention will be described. In the following embodiments, an inkjet recording head and an inkjet recording device that eject ink will be described in a specific configuration, but the present invention is not limited thereto. For example, the present invention is applicable not only to printers with line heads but also to printers with serial heads. Further, the liquid ejection head, the liquid ejection device, and the liquid supply method of the present invention are applicable to devices such as printers, copiers, facsimiles having a communication system, word processors having a printer unit, and further industrial recording devices that are combined in a complex manner with various processing devices. For example, it can also be used for applications such as biochip production and electronic circuit printing. The embodiments described below are specific examples of the present invention, and thus various technically preferable limitations are imposed. However, as long as it conforms to the idea of the present invention, the embodiments are not limited to the embodiments described below or other specific methods.

[0010] <Regarding the internal configuration of the recording device> FIG. 1 is an internal configuration diagram of an inkjet recording device 1 (hereinafter, the recording device 1). 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 device 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 individually or in conjunction with the printing unit 2 and the scanner unit 3. The scanner unit 3 is equipped with an ADF (Automatic Document Feeder) and an FBS (Flatbed Scanner), and can read a document automatically fed by the ADF and a document placed on the platen of the FBS by the user (scan). Here, a multifunction device having both the printing unit 2 and the scanner unit 3 is shown, but a form without the scanner unit 3 may also be used. FIG. 1 shows a standby state in which 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. A relatively small recording medium up to A4 size is accommodated in the first cassette 5A, and a relatively large recording medium up to A3 size is 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 boost 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 boost 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 double-sided 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 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. 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 the print controller 202 described later so that the ejection port surface 8a faces the platen 9. The platen 9 is composed of 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. Here, the four colors of ink refer to cyan (C), magenta (M), yellow (Y), and black (K) inks. 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. The recording apparatus 1 has a circulating ink supply system, 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] <Control Configuration of the Recording Device> FIG. 2 is a block diagram showing the control configuration in the recording device 1. The recording device 1 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 device 1. The print controller 202 controls various mechanisms of the print engine unit 200 according to the instructions of 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. Hereinafter, the details of the control configuration will be described.

[0019] In the controller unit 100, the main controller 101 composed of a CPU controls the entire recording device 1 while using the RAM 106 as a work area according to the 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 the instructions of 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 device 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 device 1. The communication method used for wireless communication or wired communication is not limited. For example, as the communication method used for wireless communication, Wi-Fi (Wireless Fidelity) (registered trademark) or Bluetooth (registered trademark) is applicable. Also, as the communication method used for wired communication, USB (Universal Serial Bus) or the like is 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 engine unit 300 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 device 1. The user can instruct operations such as copy and scan, set the printing mode, or recognize information of the recording device 1 via the operation panel 104.

[0022] In the print engine unit 200, a print controller 202 composed of 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. To enable the recording head 8 to 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 feeding units 6A and 6B, the conveying roller 7, the discharging 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 instructions 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 cleaning mechanisms such as 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. Thereby, various mechanisms provided in the scanner unit 3 are controlled. For example, when the main controller 101 controls the hardware resources in the scanner controller 302 via the controller I / F 301, the original document mounted 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] <Regarding the operation of the recording device in the recording state> FIG. 3 shows the recording device 1 in the 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. The plane of the platen 9 is inclined at about 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 about 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 uses the maintenance control unit 210 to lower the cap unit 10 to the retracted position shown in FIG. 3. Thereby, 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 as described 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. After that, 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-sized recording medium S accommodated 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 passes through the left side of the flapper 11 with its leading edge tilted to the right while being guided by the conveyance roller 7 and the impeller 7b, and is conveyed upward in the vertical direction of the recording apparatus 1 along the guide 18. FIG. 4(b) shows the state in which 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 impeller 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 to the discharge tray 13 by the discharge roller 12 and the boost 7b. FIG. 4(c) shows a state where the leading edge of the recording medium S passes through the discharge roller 12 and is discharged to 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] FIGS. 5(a) to (c) are diagrams showing the conveyance path when the A3-size recording medium S housed in the second cassette 5B is fed. The recording medium S loaded on the top in 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] FIG. 5(a) shows the conveyance state immediately before the leading edge of the recording medium S reaches the recording area P. A plurality of conveyance rollers 7, pinch rollers 7a, and inner guides 19 are arranged in the conveyance path from when the recording medium S is fed by the second feeding unit 6B until it reaches the recording area P, so that the recording medium S is curved in an S shape and conveyed to the platen 9.

[0033] The subsequent conveyance path is the same as that for the A4-size recording medium S shown in FIGS. 4(b) and (c). FIG. 5(b) shows a state where the leading edge of the recording medium S passes through the recording area P and is conveyed upward in the vertical direction. FIG. 5(c) shows a state where the leading edge of the recording medium S passes through the discharge roller 12 and is discharged to the discharge tray 13.

[0034] FIGS. 6(a) to (d) show the conveyance path when a recording operation (double-sided recording) is performed on the back surface (second surface) of the A4-size recording medium S. When performing double-sided recording, the recording operation is performed on the second surface (back surface) after recording the first surface (front surface). Since the conveyance process when recording the first surface is the same as that in FIGS. 4(a) to (c), the description thereof is omitted here. Hereinafter, the conveyance process after FIG. 4(c) will be described.

[0035] When the recording operation on the first surface by the recording head 8 is completed and the rear 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 flapper 11 is controlled by an actuator (not shown) so that its tip inclines to the left side, the front end of the recording medium S (the rear end in the recording operation on the first surface) passes through the right side of the flapper 11 and is conveyed vertically downward. FIG. 6(a) shows a state where the front end of the recording medium S (the rear end in the recording operation on the first surface) passes through the right side of the flapper 11.

[0036] 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 surface of the recording medium S faces the discharge port surface 8a of the recording head 8. FIG. 6(b) shows a conveyance state immediately before the front end of the recording medium S reaches the recording area P for the recording operation on the second surface.

[0037] The subsequent conveyance path is the same as that in the case of recording the first surface shown in FIGS. 4(b) and (c). FIG. 6(c) shows a state where the front end of the recording medium S passes through the recording area P and is conveyed vertically upward. At this time, the flapper 11 is controlled by an actuator (not shown) to move to a position where its tip inclines to the right side. FIG. 6(d) shows a state where the front end of the recording medium S passes through the discharge roller 12 and is discharged to the discharge tray 13.

[0038] <Regarding the maintenance operation for the recording head> Next, the maintenance operation for the recording head 8 will be described. As also described in FIG. 1, the maintenance unit 16 includes a cap unit 10 and a wiping unit 17, and performs a maintenance operation by operating these at a predetermined timing.

[0039] FIG. 7 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. 7, 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. 7. After that, the print controller 202 moves the recording head 8 downward in the vertical direction to move it to a maintenance position where maintenance operations are possible.

[0040] 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. 7, the print controller 202 moves the recording head 8 upward in the vertical direction while rotating it 45 degrees. Then, the print controller 202 moves the wiping unit 17 from the retracted position to the right direction. After that, the print controller 202 moves the recording head 8 downward in the vertical direction to move it to a maintenance position where maintenance operations by the maintenance unit 16 are possible.

[0041] FIG. 8(a) is a perspective view showing a state where the maintenance unit 16 is in the standby position, and FIG. 8(b) is a perspective view showing a state where the maintenance unit 16 is in the maintenance position. FIG. 8(a) corresponds to FIG. 1, and FIG. 8(b) corresponds to FIG. 7. When the recording head 8 is in the standby position, the maintenance unit 16 is in the standby position shown in FIG. 8(a), the cap unit 10 is moved upward in the vertical direction, 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. The cap member 10a is provided with an absorber capable of absorbing and holding a predetermined amount of ink. Further, the cap unit 10 also has a function of collecting the ink discharged by preliminary discharge or the like on the cap member 10a and causing the collected ink to be sucked by a suction pump (not shown) (cap suction).

[0042] On the other hand, in the maintenance position shown in FIG. 8(b), the cap unit 10 has moved downward in the vertical direction, 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.

[0043] 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 while being positioned at a height where the recording head 8 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.

[0044] At the entrance of the maintenance unit 16 when the blade wiper 171a is stored, a wet wiper cleaner 16a for removing the ink adhering to the blade wiper 171a and applying a wetting liquid to the blade wiper 171a is arranged. Each time the blade wiper 171a is stored in the maintenance unit 16, the adhering matter is 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.

[0045] On the one 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 such that the discharge port surface 8a can be wiped in the y direction as the carriage 172b moves. A suction port connected to a suction pump (not shown) is formed at the tip of the vacuum wiper 172c. Therefore, when the carriage 172b is moved in the y direction while operating the suction pump, the ink or the like adhering to the discharge port surface 8a of the recording head 8 is 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.

[0046] The wiping unit 17 can perform a first wiping process in which the wiping operation by the blade wiper unit 171 is carried out and the wiping operation by the vacuum wiper unit 172 is not carried out, and a second wiping process in which both wiping processes are carried out in sequence. When performing the first wiping process, the print controller 202 first 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. 7. 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. By this movement, the 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.

[0047] When the blade wiper unit 171 is stored, 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, in that state, the print controller 202 drives the recording head 8 to perform preliminary discharge and sucks the ink collected in the cap member 10a by a suction pump.

[0048] 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 in FIG. 7. 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. Thereby, 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 again with the recording head 8 retracted vertically upward from the maintenance position in FIG. 7. 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. 7. 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 the preliminary discharge into the cap member by the cap unit 10 and the suction operation of the collected ink in the same manner as the first wiping process.

[0049] <Regarding the ink supply unit> FIG. 9 is a diagram showing an ink supply unit 15 employed in the inkjet recording apparatus 1 of the present embodiment. The ink supply unit 15 is configured to supply ink from the ink tank unit 14 to the recording head 8. Here, 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 unit will be described.

[0050] The ink mainly circulates between the sub-tank 151 and the recording head 8 (head unit in FIG. 9). In the head unit 8, an ink ejection operation is performed based on image data, and the ink that has not been ejected is collected again into the sub-tank 151.

[0051] The sub-tank 151 that stores a predetermined amount of ink is connected to a supply channel C2 for supplying ink to the head unit 8 and a recovery channel C4 for recovering ink from the head unit 8. That is, a circulation path for the ink is formed by the sub-tank 151, the supply channel C2, the head unit 8, and the recovery channel C4.

[0052] The sub-tank 151 is provided with a liquid level detection means 151a composed of a plurality of 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 decompression pump P0 is a negative pressure generation source for decompressing the inside 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.

[0053] The main tank 141 is a tank that stores the ink supplied to the sub-tank 151. The main tank 141 is composed of a flexible member, and the sub-tank 151 is filled with ink due to the volume change of the flexible member. The main tank 141 is configured to be detachable from the recording apparatus main body. In the middle of the tank connection flow path 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.

[0054] Under the above configuration, 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, the atmosphere release valve V0, the supply valve V2, the recovery valve V4, and the head replacement valve V5 are closed, and the tank supply valve V1 is opened. 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.

[0055] The supply flow path C2 is a flow path for supplying ink from the sub-tank 151 to the head unit 8. In the middle of it, a supply pump P1 and a supply valve V2 are arranged. During the recording operation, by driving the supply pump P1 with the supply valve V2 open, ink can be supplied to the head unit 8 and circulated in the circulation path. The amount of ink ejected per unit time by the head unit 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 head unit 8 performs a ejection operation in which the ink ejection amount per unit time is maximum.

[0056] The relief channel C3 is a channel that is 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. When the ink supply amount per unit time from the supply pump P1 is greater than the total value of the discharge amount per unit time of the head unit 8 and the flow rate (ink suction amount) per unit time in the recovery pump P2, 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 head unit 8 is adjusted according to the ink discharge amount in the head unit 8, and the flow pressure in the circulation path can be stabilized regardless of the image data.

[0057] The recovery channel C4 is a channel for recovering ink from the head unit 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 and sucks ink from the head unit 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 head unit 8, and ink can be circulated between the IN channel 80b and the OUT channel 80c. The channel configuration in the head unit 8 will be described in detail later.

[0058] The recovery valve V4 is 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 head unit 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 head unit 8 due to the head difference between the sub-tank 151 and the head unit 8. To prevent such backflow, a recovery valve V4 is provided in the recovery channel C4 in the present embodiment.

[0059] Similarly, the supply valve V2 also functions as a valve for preventing the backflow of ink from the sub-tank 151 to the head unit 8 when the recording operation is not being performed, that is, when the ink is not being circulated in the circulation path.

[0060] The head replacement flow path C5 is a flow path that connects the supply flow path C2 and the air layer (the portion where no ink is stored) of the sub-tank 151. A head replacement valve V5 is arranged in the middle of it. One end of the head replacement flow path C5 is connected upstream of the head unit 8 in the supply flow path C2, and the other end is connected above the sub-tank 151 to communicate with the internal air layer. The head replacement flow path C5 is used when recovering ink from the head unit 8 in use, such as when replacing the head unit 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 initially filling the recording apparatus 1 with ink and when recovering ink from the head unit 8. Further, the above-described supply valve V2 is provided between the connection portion with the head replacement flow path C5 and the connection portion with the relief flow path C3 in the supply flow path C2.

[0061] Next, the flow path configuration inside the head unit 8 will be described. The ink supplied from the supply flow path C2 to the head unit 8 passes through the filter 83 and is then supplied to a first negative pressure control unit 81 that generates a weak negative pressure and a second negative pressure control unit 82 that generates a strong negative 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.

[0062] The ink ejection unit 80 is provided with a plurality of recording element substrates 80a each having a plurality of ejection portions with ejection ports arranged therein, and a long ejection port row is formed. A common supply channel 80b (IN channel) for guiding ink supplied from the first negative pressure control unit 81 and a common recovery channel 80c (OUT channel) for guiding 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 in 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. 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 discharged by being ejected from the ejection port, but the ink that is not ejected moves to the recovery channel C4 via the common recovery channel 80c.

[0063] 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 the sub-tank 151 → supply channel C2 → head unit 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 head unit 8 and the flow rate per unit time in the recovery pump P2, ink flows from the supply channel C2 into the relief channel C3. Thereby, the flow rate of the ink flowing into the head unit 8 from the supply channel C2 is adjusted.

[0064] When the recording operation is not being performed, 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. As a result, the flow of ink in the head unit 8 stops, and backflow due to the head difference between the sub-tank 151 and the head unit 8 is also suppressed. Also, by closing the atmosphere release valve V0, ink leakage from the sub-tank 151 and evaporation of the ink are suppressed.

[0065] When recovering ink from the head unit 8, the ink supply control unit 209 closes the tank supply valve V1, the supply valve V2, and the recovery valve V4, opens the atmosphere release valve V0 and the head replacement valve V5, and drives the pressure reducing pump P0. As a result, the inside of the sub-tank 151 becomes a negative pressure state, and the ink in the head unit 8 is recovered into the sub-tank 151 via the head replacement flow path C5. In this way, the head replacement valve V5 is a valve that is closed during normal recording operations and standby, and is opened when recovering ink from the head unit 8. However, the head replacement valve V5 is also opened when filling the head replacement flow path C5 with ink during the initial filling of the head unit 8.

[0066] <Regarding the ejection unit> FIG. 10(a) is an enlarged plan schematic view of a part of the recording element substrate 80a, and FIG. 10(b) is a cross-sectional schematic view taken along the section line Xb-Xb of FIG. 10(a). The recording element substrate 80a is provided with a pressure chamber 1005 filled with ink and a discharge port 1006 for discharging the ink. In the pressure chamber 1005, a recording element 1004 is provided at a position facing the discharge port 1006. Also, on the recording element substrate 80a, a plurality of individual supply channels 1008 connected to the common supply channel 80b and a plurality of individual recovery channels 1009 connected to the common recovery channel 80c are formed for each discharge port 1006.

[0067] With the above-described configuration, in the recording element substrate 80a, an ink flow is generated that flows in from the common supply channel 80b with relatively weak negative pressure (high pressure) and flows out to the common recovery channel 80c with relatively strong negative pressure (low pressure). More specifically, the ink flows in the order of common supply channel 80b → individual supply channel 1008 → pressure chamber 1005 → individual recovery channel 1009 → common recovery channel 80c. When the ink is ejected by the recording element 1004, a part of the ink that moves from the common supply channel 80b to the common recovery channel 80c is ejected from the ejection port 1006 and discharged to the outside of the head unit 8. On the other hand, the ink that has not been ejected from the ejection port 1006 is recovered to the recovery channel C4 through the common recovery channel 80c.

[0068] <Regarding preliminary ejection> Preliminary ejection is an operation for discharging the ink pushed into the ejection port and mixed by the wiping process at a position unrelated to recording. The preliminary ejection is performed after the above-described first wiping process or second wiping process. This is because, in the wiping process, the ejection port rows are sequentially wiped, so during a series of wiping operations, the ink wiped by the front-stage ejection port row adheres to the rear-stage ejection port row during the wiping of the rear-stage ejection port row, and mixed ink remains. Therefore, after the wiping process, the preliminary ejection is performed on the cap member 10a. By this preliminary ejection, the ink mixed in the ejection port is discharged.

[0069] Hereinafter, based on the basic configuration described so far, a preferred embodiment of the present invention will be described.

[0070] [First Embodiment] This embodiment assumes a case where the recording head (the ejection port surface) is capped by the cap mechanism for a long time. In such a cap-closed state, although the progress speed is slower compared to the cap-open state, the evaporation of the ink proceeds. Therefore, even in the cap-closed state, if the evaporation of the ink proceeds after a long time, there is a risk that the concentrated ink will stay at the ejection port and it will become difficult to eject the ink from the ejection part. Thus, in this embodiment, when a predetermined time has elapsed in the cap-closed state, the ink is circulated to keep the inside of the recording head in a printable state.

[0071] <Regarding the timer circulation process> Hereinafter, the process (referred to as the timer circulation process) of counting time with a timer and circulating the ink when a predetermined time has elapsed in this embodiment will be described with reference to FIG. 11. Note that the following process starts when the recording apparatus 1 is in the cap-open state, that is, the ejection port surface 8a is not capped by the cap unit 10 (for example, the state in FIG. 3).

[0072] In step S1101, the print controller 202 controls the maintenance control unit 210 to move the cap unit 10 that is not capping the ejection port surface 8a, thereby transitioning the recording head 8 from the cap-open state to the cap-closed state.

[0073] In step S1102, the print controller 202 starts a timer in the cap-closed state. This timer is a timer provided in the recording apparatus 1 and counts the duration of the cap-closed state (referred to as the capping time). The print controller 202 can acquire the capping time at an arbitrary timing.

[0074] In step S1103, the print controller 202 determines whether a predetermined time (for example, 6 hours) has elapsed, that is, whether the counter started in step S1102 has counted the predetermined time. If the determination result in step S1103 is true, the process proceeds to step S1104. On the other hand, if the determination result is false, the process proceeds to step S1106.

[0075] In step S1104, the print controller 202 controls the ink supply control unit 209 to circulate the ink within the above-described circulation path. As a result, an ink flow is generated in the ejection unit 1000 within the recording head 8. FIG. 12 shows a state in which the thickened ink staying in the discharge port 1006 flows out from the individual recovery flow path 1009 due to the ink flow 1201 generated in this step. The vertical axis corresponds to the time axis, and the passage of time is shown from top to bottom in FIG. 12. As shown in FIG. 12, the ink staying in the discharge port 1006 diffuses due to the ink flow 1201 generated each time the predetermined time elapses, and the discharge port 1006 is filled with fresh ink. As a result, the discharge stability (the property of being able to stably discharge ink from the discharge port) of the ejection unit 1000 (at the discharge port 1006) is restored.

[0076] In step S1105, the print controller 202 resets the timer.

[0077] In step S1106, the print controller 202 determines whether there is a printing instruction. If this determination result is true, the timer circulation process ends. If the determination result in step S1106 is false, the process returns to step S1103 and the timer circulation process continues. The above is the content of the timer circulation process in the present embodiment.

[0078] <Regarding the effects of the present embodiment> According to the present embodiment, when the recording head 8 is capped by the cap unit 10 for a long time, it is possible to prevent the discharge port 1006 from being clogged with concentrated ink and ensure the discharge stability of the ejection unit 1000.

[0079] [Second Embodiment] In this embodiment, a case will be described in which the time interval (referred to as the circulation interval) for circulating the ink is changed according to the installation environment of the recording apparatus 1, specifically the temperature and humidity. In the following, mainly the differences from the above-described embodiment will be described, and the description of the same content as the above-described embodiment will be omitted as appropriate.

[0080] <Regarding Timer Circulation Processing> Hereinafter, the timer circulation processing in this embodiment will be described with reference to FIG. 13(a).

[0081] In step S1310, the print controller 202 controls the maintenance control unit 210 to move the cap unit 10 that does not cap the discharge port surface 8a, thereby transitioning the recording head 8 from the cap open state to the cap closed state.

[0082] In step S1320, the print controller 202 executes a process of counting the evaporation rate of the ink in the cap unit 10 (referred to as the in-cap evaporation rate counting process). The details of the in-cap evaporation rate counting process will be described later with reference to FIG. 13(b).

[0083] In step S1330, the print controller 202 derives the circulation interval. Specifically, the print controller 202 functions as a circulation interval derivation means, and referring to the table as shown in Fig. 14(a), it derives the value of the circulation interval corresponding to the cap internal evaporation rate count value obtained in step S1320. When using the table shown in Fig. 14(a), for example, when the cap internal evaporation rate count value is 200, the circulation interval is 18 hours. Note that the table in Fig. 14(a) is merely an example, and other tables that hold the value range of the cap internal evaporation rate count and the corresponding values of the circulation interval may be used. However, in such tables, generally, the larger the cap internal evaporation rate count value, the shorter the set circulation interval. This is because the higher the cap internal evaporation rate count value, the more the ink evaporation progresses and thus it is more likely to thicken, so it is necessary to frequently execute the ink circulation. Note that here, the case of using a table has been described, but instead of a table, a mathematical formula into which the cap internal evaporation rate count value is substituted may be used to calculate the circulation interval.

[0084] In step S1340, the print controller 202 starts a timer that counts the capping time.

[0085] In step S1350, the print controller 202 determines whether the count value of the timer started in step S1340 has reached the circulation interval derived in step S1330. If the determination result in step S1350 is true, it proceeds to step S1360, while if the determination result is false, it proceeds to step S1380.

[0086] The process of step S1360 is the same as the process of step S1104, and the process of step S1370 is the same as the process of step S1105. After step S1370, it proceeds to step S1380.

[0087] In step S1380, the print controller 202 determines whether there is a printing instruction. If this determination result is true, the timer loop process ends. On the other hand, if the determination result is false, the process proceeds to step S1390.

[0088] In step S1390, the print controller 202 determines whether a predetermined time (for example, one week) has elapsed since the cap was closed in step S1310. This step is a process executed to end the timer loop process when it is expected that the recording device 1 will not be used for a long time and there is little need to keep the inside of the recording head 8 in a printable state. Note that the process of this step may be executed in the flow of the first embodiment. If the determination result of step S1390 is true, the timer loop process ends. On the other hand, if the determination result is false, the process returns to step S1350 and the timer loop process continues. The above is the content of the timer loop process in this embodiment.

[0089] <Regarding the cap internal evaporation rate counting process> Hereinafter, the above-described cap internal evaporation rate counting process (step S1320) will be described in detail with reference to FIG. 13(b).

[0090] In step S1321, the print controller 202 acquires the current cap internal evaporation rate count value. Here, the cap internal evaporation rate is a parameter indicating the degree of progress of evaporation of the ink in the ejection unit 1000 capped by the cap unit 10, and is counted by the print controller. The current cap internal evaporation rate count value is stored in the ROM 203.

[0091] In step S1322, the print controller 202 acquires the temperature and humidity of the installation environment of the recording device 1. Note that the recording device 1 is provided with a thermometer and a hygrometer, and the print controller 202 can acquire the temperature and humidity of the installation environment of the recording device 1 at an arbitrary timing.

[0092] In step S1323, the print controller 202 derives an evaporation rate coefficient corresponding to the temperature and humidity acquired in step S1322. Hereinafter, the method for deriving this evaporation rate coefficient will be described in detail.

[0093] First, based on the temperature and humidity acquired in step S1322, the state of the installation environment (referred to as the temperature and humidity state) is classified using a graph as illustrated in FIG. 14(b). When using the graph shown in FIG. 14(b), it is classified into any one of a first temperature and humidity state 1401, a second temperature and humidity state 1402, and a third temperature and humidity state 1403. The first temperature and humidity state 1401 is a low-temperature and high-humidity state, that is, a state in which ink is difficult to concentrate. The third temperature and humidity state 1403 is a high-temperature and low-humidity state, that is, a state in which ink is easy to concentrate. The second temperature and humidity state 1402 is an intermediate state between the first temperature and humidity state 1401 and the third temperature and humidity state 1403.

[0094] Next, referring to a table as illustrated in FIG. 14(c), an evaporation rate coefficient corresponding to the temperature and humidity state classified above is derived. As shown in FIG. 14(c), the higher the state in which ink is easy to concentrate, the larger the evaporation rate coefficient. Note that the graph shown in FIG. 14(b) and the table shown in FIG. 14(c) are merely examples, and other graphs and tables may be used. A graph for classifying the temperature and humidity state based on such temperature and humidity, and a table storing the evaporation rate coefficient for each temperature and humidity state are stored in advance in the ROM 203, and the print controller 202 can use these at any timing.

[0095] In step S1324, the print controller 202 acquires the cumulative time [minutes] of the cap open state (referred to as the cap open time) between the previous cap internal evaporation rate count process and the current cap internal evaporation rate count process. Note that the recording device 1 includes a timer that counts the cap open time, and the print controller 202 can acquire the cap open time at any timing.

[0096] In step S1325, the print controller 202 multiplies the evaporation rate coefficient derived in step S1323 by the cap open time acquired in step S1324. Then, the value obtained by this multiplication is added to the current in-cap evaporation rate count value acquired in step S1321.

[0097] In step S1326, the print controller 202 updates the in-cap evaporation rate count value. Specifically, the in-cap evaporation rate count value stored in the ROM 203 is overwritten and saved with the value calculated in step S1325.

[0098] In step S1327, the print controller 202 determines whether the in-cap evaporation rate count value is equal to or greater than a predetermined threshold (in this example, 500 or more). Note that the threshold value of 500 mentioned here is just an example, and if the table used in step S1330 changes, naturally the threshold value used in this step will also change. If the determination result in step S1327 is true, the process proceeds to step S1328. On the other hand, if the determination result is false, the in-cap evaporation rate count process ends (proceeds to step S1330).

[0099] In step S1328, the print controller 202 drives the recording element 1004 to perform preliminary ink ejection. Alternatively, the print controller 202 may control the maintenance control unit 210 to perform cap suction. When the in-cap evaporation rate count value is 500 or more (YES in step S1327), the evaporation of the ink has progressed considerably, and it is difficult to restore the ejection stability of the ejection unit 1000 only by circulation. Therefore, by performing preliminary ejection or cap suction in this step, the ejection stability is restored.

[0100] In step S1329, the print controller 202 resets (sets to 0) the in-cap evaporation rate count value. After step S1329, the in-cap evaporation rate count process ends (proceeds to step S1330). The above is the content of the in-cap evaporation rate count process in this embodiment.

[0101] <Regarding the modification of this embodiment> <In the above example, the circulation interval was derived based on the temperature and humidity of the recording apparatus 1, but the circulation interval may be derived based on either the temperature or the humidity. Also, in the above example, the evaporation rate inside the cap was reset in step S1329, but a method of subtracting the count value according to the amount of preliminary discharge or the intensity of cap suction may be used. Further, when a mechanism capable of deriving ink density information as described later in the fourth embodiment is provided, the subtraction value of the evaporation rate inside the cap may be changed according to the density information.>

[0102] <Regarding the effects of this embodiment> <According to this embodiment, it becomes possible to circulate the ink at a frequency according to the installation environment of the recording apparatus 1, that is, the temperature and humidity, and keep the inside of the recording head 8 in a printable state (ensuring the discharge stability of the discharge unit 1000).>

[0103] [Third Embodiment] <In the second embodiment, the evaporation rate inside the cap was counted in consideration of the evaporation of the ink in the cap open state. In contrast, in this embodiment, the evaporation rate inside the cap is counted in consideration of the evaporation of the ink in the cap closed state.>

[0104] <Regarding the timer circulation process> <Hereinafter, the timer circulation process in this embodiment will be described with reference to FIG. 15(a).>

[0105] <The processes of steps S1510 to S1560 are the same as the processes of steps S1310 to S1360.>

[0106] <In step S1570, the print controller 202 executes a cap internal evaporation rate addition process during cap closure, in which the variation in the cap internal evaporation rate due to the evaporation of the ink that progresses during cap closure is added to the count value of the cap internal evaporation rate. Note that the details of the cap internal evaporation rate counting process during cap closure will be described later with reference to FIG. 15(b).>

[0107] The processes from step S1590 to step S1600 are the same as the processes from step S1380 to step S1390. However, in this embodiment, when the result in step S1600 is NO, the process returns to step S1530 to derive the circulation interval again. Thus, in this embodiment, the circulation interval is derived every time the circulation is executed (step S1560 → ··· → step S1600 with NO → step S1530), and thereby, it is possible to execute the circulation at an appropriate interval.

[0108] <Regarding the cap internal evaporation rate addition process during cap closing> Hereinafter, the above-described cap internal evaporation rate addition process (step S1570) during cap closing will be described in detail with reference to FIG. 15(b).

[0109] In step S1571, the print controller 202 acquires the current cap internal evaporation rate count value.

[0110] In step S1572, the print controller 202 acquires the temperature and humidity of the installation environment of the recording device 1.

[0111] In step S1573, the print controller 202 derives an evaporation rate coefficient corresponding to the temperature and humidity acquired in step S1572. Hereinafter, the method for deriving this evaporation rate coefficient will be described in detail.

[0112] First, similar to the second embodiment, based on the temperature and humidity acquired in step S1572, the temperature and humidity state of the installation environment is classified using a graph as illustrated in FIG. 14(b).

[0113] Next, referring to the table as illustrated in FIG. 15(c), an evaporation rate coefficient corresponding to the classified temperature and humidity state is derived. As shown in FIG. 15(c), the higher the state in which the ink is likely to be concentrated, the larger the evaporation rate coefficient. However, since the cap closed state is a state in which the evaporation of the ink is less likely to proceed compared to the cap open state, the values of the evaporation rate coefficient held in the table of FIG. 15(c) are generally smaller than the values of the evaporation rate coefficient held in the table of FIG. 14(c). Note that the table shown in FIG. 15(c) is merely an example, and other tables may be used.

[0114] In step S1574, the print controller 202 acquires the capping time.

[0115] In step S1575, the print controller 202 multiplies the evaporation rate coefficient derived in step S1573 by the capping time acquired in step S1574. Then, the value obtained by this multiplication is added to the current in-cap evaporation rate count value acquired in step S1571.

[0116] In step S1576, the print controller 202 updates the in-cap evaporation rate count value. Specifically, the in-cap evaporation rate count value stored in the ROM 203 is overwritten and saved with the value calculated in step S1575.

[0117] The processing of steps S1577 to S1579 is the same as the processing of steps S1327 to S1329. The above is the content of the in-cap evaporation rate addition process during cap closure in the present embodiment.

[0118] <Regarding the effects of the present embodiment> In this embodiment, in addition to the evaporation of ink in the cap-open state, the evaporation rate inside the cap is counted in consideration of the evaporation of ink in the cap-closed state. Therefore, based on the evaporation rate inside the cap derived with higher accuracy than in the second embodiment, ink can be circulated at a more appropriate frequency than in the second embodiment to keep the inside of the recording head 8 in a printable state (ensuring the discharge stability of the discharge unit 1000).

[0119] [Fourth Embodiment] In this embodiment, the recording apparatus 1 is provided with a mechanism for deriving the concentration information of ink, and a case where the circulation interval of the ink is changed according to the concentration information will be described.

[0120] [Regarding Concentration Information] The concentration information will be described below. In this embodiment, when determining the circulation interval, the print controller 202 acquires the concentration information (concentration N C shall be) of the ink. Note that the value calculated by the following formula is stored in the ROM 203 as the concentration N C , and the print controller 202 can acquire the concentration N C at an arbitrary timing.

[0121] [Equation]

[0122] Here, N X+1 represents the concentration after the recording operation, N X represents the concentration before the recording operation. Also, J n represents the amount of ink in the ink circulation system before the recording operation, I n represents the amount of ink ejected by the recording, and V represents the evaporation amount from the circulation system. The print controller 202 calculates N X+1 for each recording operation, and overwrites and stores the calculated value in the ROM 203 as the concentration N C .

[0123] [Method for Deriving Circulation Interval Based on Concentration Information] The print controller 202 refers to a table as illustrated in FIG. 16 and derives the circulation interval corresponding to the acquired density N. C When using the table shown in FIG. 16, for example, when the in-cap evaporation rate count value is 200 and the density N C is 0.087, the circulation interval is 13.5 hours. Note that the table in FIG. 16 is merely an example, and other tables that hold the value ranges of the in-cap evaporation rate count and the density N C and the values of the circulation intervals corresponding thereto may be used. However, in such a table, generally, the larger the in-cap evaporation rate count value or the higher the density N C is, the shorter the circulation interval is set. This is because the higher the value of the in-cap evaporation rate count or the higher the density N C is, the more the evaporation of the ink progresses and the easier it is to thicken, so it is necessary to frequently execute the ink circulation. Note that here, the case of using a table has been described, but instead of the table, a mathematical formula into which the in-cap evaporation rate count value and the density N C are substituted may be used to calculate the circulation interval.

[0124] <Regarding the effects of this embodiment> In this embodiment, the circulation interval is derived in consideration of not only the in-cap evaporation rate count value but also the density information of the ink. Therefore, it becomes possible to circulate the ink at an appropriate frequency more than in the above-described embodiment and keep the inside of the recording head 8 in a printable state (ensuring the discharge stability of the discharge unit 1000).

[0125] [Fifth Embodiment] In this embodiment, the case of changing the time for circulating the ink (referred to as the circulation execution time) according to the temperature will be described.

[0126] The print controller 202 refers to a table as shown in Fig. 17(a) and derives the circulation execution time corresponding to the acquired temperature. Here, the temperature acquired by the print controller 202 may be the temperature in the installation environment of the recording device 1 described above. Alternatively, when the recording device 1 is equipped with a mechanism for measuring the temperature of the recording head 8, the measured temperature of the recording head 8 may be used.

[0127] When using the table shown in Fig. 17(a), for example, when the temperature is 20°C, the circulation execution time is 2 minutes. Note that the table in Fig. 17(a) is only an example, and other tables that hold the temperature value range and the corresponding circulation execution time values may be used. However, in such tables, generally, the higher the temperature, the shorter the set circulation execution time. This is because, as shown in Fig. 17(b), the higher the temperature, the lower the viscosity of the ink, so the discharge stability of the discharge unit 1000 can be restored with a short circulation execution time. Here, the case of using a table has been described, but instead of a table, a mathematical formula into which the temperature value is substituted may be used to calculate the circulation execution time.

[0128] <Regarding the effects of this embodiment> According to this embodiment, it becomes possible to execute circulation at an appropriate time according to the temperature.

[0129] [Sixth Embodiment] In this embodiment, the recording device 1 is equipped with a head temperature control mechanism for adjusting the temperature of the recording head 8, and the case where the circulation execution time is changed according to the set temperature of the temperature control will be described.

[0130] The print controller 202 derives the circulation execution time corresponding to the set temperature of temperature control obtained by referring to a table as shown in FIG. 18. Note that the table in FIG. 18 is merely an example, and other tables that hold the values of the set temperature of temperature control and the corresponding values of the circulation execution time may be used. However, in such a table, generally, the higher the set temperature of temperature control, the shorter the circulation execution time is set. This is because, as described in the fifth embodiment, the higher the set temperature of temperature control, the lower the viscosity of the ink, and thus the discharge stability of the discharge unit 1000 can be restored with a short circulation execution time. Note that although the case of using a table has been described here, instead of the table, a mathematical formula into which the temperature value is substituted may be used to calculate the circulation execution time. Also, a plurality of tables as shown in FIG. 18 are stored in the ROM 203, and an embodiment in which these tables are properly selected according to the consumable power and user settings is also conceivable.

[0131] <Regarding the effects of this embodiment> According to this embodiment, it becomes possible to execute circulation for an appropriate time according to the set temperature of temperature control. Also, in this embodiment, since circulation is executed in the cap-closed state, even when the target temperature of temperature control is set to a higher temperature than during printing, it is possible to suppress the evaporation of moisture in the ink.

[0132] [Seventh Embodiment] In this embodiment, when the timer circulation process is repeated as in the first to third embodiments, the moisture evaporated from the ink at the discharge port is absorbed by the absorbent disposed in the cap member 10a or the ink impregnated in the absorbent. Considering that the inside of the cap member 10a is moistened by the absorbent or the like that has absorbed moisture in this way, and the progress of moisture evaporation from the ink at the discharge port is suppressed, the evaporation rate count inside the cap is subtracted.

[0133] Hereinafter, the timer circulation process in this embodiment will be described with reference to FIG. 19(a).

[0134] The processing from step S1910 to step S1960 is the same as the processing from step S1510 to step S1560.

[0135] In step S1970, the print controller 202 updates by adding 1 to the timer cycle count counter.

[0136] In step S1980, the print controller 202 executes a cap internal evaporation rate subtraction process by timer cycle, which subtracts the variation in the cap internal evaporation rate due to the absorber that has absorbed moisture from the count value of the cap internal evaporation rate. Note that the details of the cap internal evaporation rate subtraction process by timer cycle will be described later with reference to FIG. 19(b).

[0137] The processing from step S1990 to step S2020 is the same as the processing from step S1570 to step S1600. In this embodiment, in step S2030, the print controller 202 further resets the timer cycle count counter.

[0138] <Regarding the cap internal evaporation rate subtraction process by timer cycle> Hereinafter, the above-described cap internal evaporation rate subtraction process by timer cycle (step S1980) will be described in detail with reference to FIG. 19(b).

[0139] In step S1981, the print controller 202 acquires the current cap internal evaporation rate count value. In step S1982, the print controller 202 acquires the timer cycle count value.

[0140] In step S1983, the print controller 202 derives a subtraction value corresponding to the timer cycle count counter acquired in step S1982 by referring to a table as illustrated in FIG. 19(c). Hereinafter, the method for deriving this subtraction value will be described in detail.

[0141] When the timer cycle is performed and fresh ink that has not thickened is supplied to the discharge port, the water content of the absorber arranged in the cap member 10a increases by absorbing the water evaporated from the ink. As a result, the inside of the cap member 10a becomes moist due to the absorber with an increased water content, and the evaporation rate inside the cap becomes low.

[0142] Also, from the experimental results, it is known that the fewer the number of timer cycles, the higher the humidifying effect inside the cap per one timer cycle. Therefore, as shown in Fig. 19(c), the smaller the number of timer cycles, the larger the subtraction value subtracted from the evaporation rate count value inside the cap. As the number of timer cycles increases, the water inside the cap and the absorber becomes saturated, and the humidifying effect inside the cap due to water evaporation from the nozzles is almost lost. Therefore, when the number of timer cycles exceeds 32, the subtraction value is set to 0.

[0143] In step S1984, the print controller 202 updates the evaporation rate count value inside the cap based on the obtained subtraction value. Specifically, the print controller 202 overwrites and stores the value obtained by subtracting the subtraction value from the evaporation rate count value stored in the ROM 203.

[0144] <Regarding the effects of this embodiment> In this embodiment, the evaporation rate inside the cap is counted in consideration of the humidifying effect inside the cap due to the timer cycle. Therefore, based on the evaporation rate inside the cap derived with higher accuracy than in the third embodiment, the ink can be circulated at a more appropriate frequency than in the third embodiment to keep the inside of the recording head 8 printable (ensuring the discharge stability of the discharge unit 1000).

[0145] [Other embodiments] 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. It can also be realized by a circuit (for example, an ASIC) that realizes one or more functions.

Explanation of Signs

[0146] 8 Recording head 8a Nozzle surface 10 Cap unit 209 Ink supply control unit

Claims

【Claim 1】 A tank for storing a liquid, a recording head having a discharge port surface provided with a discharge port for discharging the liquid supplied from the tank, a cap mechanism for capping the discharge port surface, a timer for counting the time during which the discharge port surface is capped, circulation means for circulating the liquid in a circulation path including the tank and the recording head and a recording apparatus having the same, wherein when the timer counts a predetermined time, the circulation means circulates the liquid.

Images