Stirring bar, stirring device and recording device

Abstract

To provide a stirrer for improving stirring efficiency of a liquid.SOLUTION: A stirrer has a magnetic force in each of a first end and a second end opposite to the first end in a longitudinal direction of a rod-like body, and stirs a liquid, in which each of the first end and the second end that are rod-like bodies has a first blade and a second blade extending in the longitudinal direction.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention relates to a stirrer for stirring a liquid, a stirring device, and a recording device. [Background technology]

[0002] Conventionally, as a device for stirring liquid, a stirring device is known in which a stirrer having magnets at both ends of a rod-shaped body is placed in a liquid container and the stirrer is rotated by a magnetic stirrer to stir the liquid. Patent Document 1 describes a stirrer having a support extending along the rotation axis of a rod-shaped body and a stirring blade attached to the support. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2007-136443 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration of Patent Document 1, the stirring blade is provided on the support, resulting in a complex configuration. Therefore, there is a demand for a stirrer, a stirring device, or a recording device equipped with a stirring device that has a simple configuration and high stirring efficiency for liquid. The present invention provides a stirrer, a stirring device, or a recording device equipped with a stirring device that has a simple configuration and high stirring efficiency. [Means for solving the problem]

[0005] The stirrer of the present application comprises a cylindrical rod-shaped body having magnetic force at a first end in a longitudinal direction and at a second end opposite to the first end, a restricting portion extending on both sides of the rod-shaped body in the first direction in a plane perpendicular to the longitudinal direction and restricting rotation in a circumferential direction in the longitudinal direction, a plate-shaped first blade extending from the first end in the longitudinal direction and having a first front surface and a first back surface, and a plate-shaped second blade extending from the second end in the longitudinal direction and having a second front surface and a second back surface. A stirrer for stirring a liquid, When viewed from the longitudinal direction, the first surface and the second surface are line-symmetric with respect to a second direction perpendicular to the first direction and inclined with respect to the first direction, and the first back surface and the second back surface are line-symmetric with respect to the second direction and inclined with respect to the first direction. Effect of the Invention

[0006] According to the present invention, it is possible to provide a stirrer, a stirring device, or a recording device equipped with a stirring device that has a simple configuration and is highly efficient at stirring a liquid. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a diagram showing the recording device in a standby state. [Diagram 2] FIG. 2 is a control configuration diagram of the recording apparatus. [Diagram 3] FIG. 2 is a diagram showing the recording device in a recording state. [Figure 4] FIG. 2 is a diagram showing the recording apparatus in a maintenance state. [Diagram 5] FIG. 2 is a diagram illustrating a flow path configuration of an ink circulation system. [Figure 6] FIG. 2 is a diagram illustrating an ejection port and a pressure chamber. [Figure 7] FIG. 4 is a side view of the stirring mechanism. [Figure 8] FIG. [Figure 9] FIG. 4 is a cross-sectional perspective view of the stirring mechanism showing the inside of the subtank. [Figure 10] FIG. 4 is a side view showing a cross section of the stirring mechanism. [Figure 11] FIG. 4 is a cross-sectional view of the stirring mechanism viewed from above. [Figure 12] 12 is a side view showing the end of the stirring bar as viewed from a direction E shown in FIG. 11. [Figure 13] 12 is a side view showing the end of the stirring bar as viewed from a direction E shown in FIG. 11. [Figure 14] This is a graph showing the amount of bubbles generated when the stirrer is rotated once. [Figure 15] This is a graph showing the amount of bubbles reaching the liquid surface when the stirrer is rotated once. [Figure 16] FIG. 13 is a flowchart showing the stirring and deaeration operations. [Figure 17] 12 is a side view showing the end of the stirrer as viewed from the direction F shown in FIG. 11. [Figure 18] 12 is a side view showing the end of the stirrer as viewed from the direction F shown in FIG. 11. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment does not limit the present invention, and not all of the combinations of features described in the present embodiment are necessarily essential to the solution of the present invention. Note that the same configurations are described with the same reference numerals. Also, the relative arrangements, shapes, etc. of the components described in the embodiment are merely examples, and are not intended to limit the scope of the present invention to only those.

[0009] In the following description of the embodiment, "recording" includes not only the formation of significant information such as characters and figures, but also the formation of images, patterns, designs, etc. on a sheet. In the present embodiment, a roll sheet is assumed as the sheet, but cut paper, cloth, plastic film, etc. may also be used.

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

[0011] The recording device 1 is a multifunction device equipped with a print unit 2 and a scanner unit 3, and various processes related to recording and reading operations can be executed by the print unit 2 and the scanner unit 3 individually or in conjunction with each other. The scanner unit 3 is equipped with an ADF (automatic document feeder) and an FBS (flatbed scanner), and can read documents automatically fed by the ADF and read (scan) documents placed on the platen of the FBS by a user. Note that although this embodiment is a multifunction device equipped with both the print unit 2 and the scanner unit 3, it may be configured not to include the scanner unit 3. FIG. 1 shows the recording device 1 in a standby state in which neither recording nor reading operations are being performed.

[0012] In the printing section 2, a first cassette 5A and a second cassette 5B for accommodating recording media (cut sheets) S are removably installed at the bottom vertically below the housing 4. The first cassette 5A accommodates relatively small recording media up to A4 size, while the second cassette 5B accommodates relatively large recording media up to A3 size, stacked flat. A first feeding unit 6A is provided near the first cassette 5A for separating and feeding the accommodated recording media one by one. Similarly, a second feeding unit 6B is provided near the second cassette 5B. When a recording operation is performed, the recording media S is selectively fed from one of the cassettes.

[0013] The transport roller 7, discharge roller 12, pinch roller 7a, spur 7b, guide 18, inner guide 19, and flapper 11 constitute a transport mechanism for guiding the recording medium S in a predetermined direction. The transport rollers 7 are disposed upstream and downstream of the recording head 8, and are drive rollers driven by a transport motor (not shown). The pinch roller 7a is a driven roller that nips the recording medium S together with the transport roller 7 and rotates. The discharge roller 12 is disposed downstream of the transport roller 7, and is a drive roller driven by a transport motor (not shown). The spur 7b, together with the transport roller 7 and the discharge roller 12 disposed downstream of the recording head 8, pinches and transports the recording medium S.

[0014] The guide 18 is provided on the transport 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, has a curved side, and guides the recording medium S along the side. The flapper 11 is a member for switching the direction in which the recording medium S is transported during double-sided recording operation. The discharge tray 13 is a tray for stacking and holding the recording medium S discharged by the discharge roller 12 after the recording operation is completed.

[0015] The recording head 8 of this 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 in the y direction in FIG. 1 in a width corresponding to the recording medium S. That is, the recording head 8 is configured to be able to eject ink 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 a recording operation, the orientation of the recording head 8 is changed by a print controller 202 described later so that the ejection port surface 8a faces a platen 9. The platen 9 is formed 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 rear. 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 each of the four colors of ink to be supplied to the recording head 8. The ink supply unit 15 is provided in the middle of a 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 appropriate ranges. In this 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 collected from the recording head 8 to appropriate ranges.

[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.

[0018] 2 is a block diagram showing the control configuration of the recording apparatus 1. The control configuration mainly comprises a print engine unit 200 that controls the print section 2, a scanner engine unit 300 that controls the scanner section 3, and a controller unit 100 that controls the entire recording apparatus 1. A print controller 202 controls various mechanisms of the print engine unit 200 according to instructions from a 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. The control configuration will be described in detail below.

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

[0020] The recording device 1 may obtain image data from the host device 400 via wireless communication or wired communication, or may obtain 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, Wi-Fi (Wireless Fidelity) (registered trademark) or Bluetooth (registered trademark) can be used as a communication method used for wireless communication. Also, USB (Universal Serial Bus) or the like can be used as a communication method used for wired communication. Also, for example, when a read command is input from the host device 400, the main controller 101 transmits the 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 to the recording device 1. The operation panel 104 is configured, for example, with a touch panel display including a touch panel that accepts user operations and a display that displays information. The operation panel 104 may further include operation buttons. The user can instruct operations such as copying and scanning, set print modes, and recognize information about the recording device 1 via the operation panel 104.

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

[0023] The head carriage control unit 208 changes the orientation and position of the recording head 8 depending on the operating state, such as the maintenance state and recording state, of the recording device 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 falls 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 using the RAM 106 as a work area according to the program and various parameters stored in the ROM 107. This controls various mechanisms of the scanner unit 3. For example, the main controller 101 controls the hardware resources in the scanner controller 302 via the controller I / F 301, so that a document placed on the ADF by a user is conveyed via the conveyance control unit 304 and read by the sensor 305. The scanner controller 302 then stores the read image data in the RAM 303. The print controller 202 can convert the image data acquired as described above into print data, thereby causing the print head 8 to perform a print operation based on the image data read by the scanner controller 302.

[0025] Fig. 3 shows the recording apparatus 1 in a recording state. Compared to the standby state shown in Fig. 1, the cap unit 10 is spaced away from the ejection port surface 8a of the recording head 8, and the ejection port surface 8a faces the platen 9. In this embodiment, the plane of the platen 9 is inclined at about 45 degrees with respect to the horizontal direction, and the ejection port surface 8a of the recording head 8 in 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 the recording head 8 moves 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. This separates the ejection port surface 8a of the recording head 8 from the cap member 10a. Thereafter, the print controller 202 uses the head carriage control unit 208 to rotate the recording head 8 by 45 degrees while adjusting the vertical height of the recording head 8, so that the ejection 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 above steps in reverse.

[0027] Fig. 4 is a diagram showing the recording device 1 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. 4, 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 in Fig. 4. After that, the print controller 202 moves the recording head 8 downward in the vertical direction to a maintenance position where maintenance operation is possible.

[0028] On the other hand, when the recording head 8 moves from the recording position shown in Fig. 3 to the maintenance position shown in Fig. 4, the print controller 202 moves the recording head 8 vertically upward while rotating it 45 degrees. Then, the print controller 202 moves the wiping unit 17 from the retracted position to the right. After that, the print controller 202 moves the recording head 8 vertically downward to a maintenance position where the maintenance operation by the maintenance unit 16 can be performed.

[0029] <Ink supply unit (circulation system)> FIG. 5 is a diagram including an ink supply unit 15 employed in the inkjet recording apparatus 1 of this embodiment. The flow path configuration of the ink circulation system of this embodiment will be described with reference to FIG. 5. The ink supply unit 15 supplies ink supplied from the ink tank unit 14 to the recording head 8 (head unit). Although FIG. 5 shows a configuration for one color of ink, 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. Each component of the ink supply unit 15 will be described below.

[0030] The ink circulates between a sub-tank 151, which is mainly a liquid container, and the recording head 8. In the recording head 8, an ink ejection operation is performed based on image data, and ink that is not ejected is collected back into the sub-tank 151.

[0031] The subtank 151, which contains a predetermined amount of ink, is connected to a supply flow path C2 for supplying ink to the recording head 8 and a recovery flow path C4 for recovering ink from the recording head 8. In other words, the subtank 151, the supply flow path C2, the recording head 8, and the recovery flow path C4 form a circulation flow path (circulation route) through which the ink circulates. The subtank 151 is also connected to a flow path C0 through which air flows. A subtank pressure reducing valve V6 is disposed in the flow path C0 to the subtank 151.

[0032] The subtank 151 is provided with a liquid level detection means 151a consisting of multiple electrode pins. The ink supply control unit 209 can grasp the height of the ink liquid level, i.e., the remaining amount of ink in the subtank 151, by detecting the presence or absence of a conductive current between these multiple pins. The pressure reduction pump P0 (intra-tank pressure reduction pump) is a negative pressure generating source for reducing the pressure inside the subtank 151. The atmosphere release valve V0 is a valve for switching whether or not the inside of the subtank 151 is connected to the atmosphere.

[0033] The main tank 141 is a tank that contains ink to be supplied to the sub tank 151. The main tank 141 is made of a flexible member, and ink is filled into the sub tank 151 by changing the volume of the flexible member. The main tank 141 is configured to be detachable from the recording apparatus body. A tank supply valve V1 for switching the connection between the sub tank 151 and the main tank 141 is provided in the middle of a tank connection flow path C1 that connects the sub tank 151 and the main tank 141.

[0034] When the ink level detection means 151a detects that the ink in the subtank 151 is less than a predetermined amount, the ink supply control unit 209 closes the atmosphere release valve V0, the supply valve V2, the recovery valve V4, and the head replacement valve V5. The ink supply control unit 209 also opens the tank supply valve V1. In this state, the ink supply control unit 209 operates the pressure reduction pump P0. This creates a negative pressure inside the subtank 151, and ink is supplied from the main tank 141 to the subtank 151. When the ink level detection means 151a detects that the ink in the subtank 151 has exceeded a predetermined amount, the ink supply control unit 209 closes the tank supply valve V1 and stops the pressure reduction pump P0.

[0035] 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 along the way. During a recording operation, the supply pump P1 is driven with the supply valve V2 open, so that ink can be circulated in the circulation path while being supplied to the recording head 8. The amount of ink ejected per unit time by the recording head 8 varies according to image data. The flow rate of the supply pump P1 is determined so as to be able to handle the case where the recording head 8 performs an ejection operation that consumes the maximum amount of ink per unit time.

[0036] The relief flow path C3 is upstream of the supply valve V2 and is a flow path that connects the upstream and downstream sides of the supply pump P1. A relief valve V3, which is a differential pressure valve, is disposed in the middle of the relief flow path C3. The relief valve is spring-biased, not opened and closed by a drive mechanism, and is configured to open when a predetermined pressure is reached. For example, 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 recording head 8 and the flow rate (amount of ink drawn) per unit time of the recovery pump P2, the relief valve V3 opens according to the pressure acting on itself. This forms a circulating flow path consisting of a part of the supply flow path C2 and the relief flow path C3. By providing the configuration of the relief flow path C3, the ink supply amount to the recording head 8 is adjusted according to the ink consumption amount in the recording head 8, and the pressure in the circulation path can be stabilized regardless of the image data.

[0037] The recovery flow path C4 is a flow path for recovering ink from the recording head 8 to the subtank 151, and a recovery pump P2 and a recovery valve V4 are arranged along the way. When circulating ink in the circulation path, the recovery pump P2 serves as a negative pressure generating source to suck ink from the recording head 8. By driving the recovery pump P2, an appropriate pressure difference is generated between the IN flow path 80b and the OUT flow path 80c in the recording head 8, and ink can be circulated between the IN flow path 80b and the OUT flow path 80c.

[0038] The recovery valve V4 is also a valve for preventing backflow when no printing operation is being performed, i.e., when no ink is circulating in the circulation path. In the circulation path of this embodiment, the subtank 151 is disposed vertically above the recording head 8 (see FIG. 1). Therefore, when the supply pump P1 and the recovery pump P2 are not driven, there is a risk that ink will flow back from the subtank 151 to the recording head 8 due to the head difference between the subtank 151 and the recording head 8. To prevent such backflow, in this embodiment, the recovery valve V4 is provided in the recovery flow path C4.

[0039] In addition, a check valve V7 is disposed downstream of the recovery valve V4 in the recovery flow passage C4. The check valve V7 is a one-way valve that allows ink to pass from the upstream to the downstream of the flow passage while blocking ink (backflow) from downstream to the upstream. As described above, the recovery valve V4 (drive valve) is driven and controlled by the ink supply control unit 209 to close the valve when circulation stops in order to prevent backflow. However, for example, if the power is turned off during circulation, the recovery valve V4 may not close and backflow may occur. Therefore, by disposing the check valve V7, which is a one-way valve, in the recovery flow passage C4, it is possible to prevent backflow of ink to the recording head 8 even when the recovery valve V4 does not close. The check valve V7 includes, for example, a spring and a seal portion. The seal portion is biased by a spring, and is configured to open the flow passage when a predetermined pressure difference occurs between the upstream and downstream sides of the check valve V7 and open the seal portion.

[0040] In addition, the supply valve V2 also functions as a valve to prevent the supply of ink from the subtank 151 to the print head 8 when no printing operation is being performed, i.e., when ink is not circulating in the circulation path.

[0041] The head replacement flow path C5 is a flow path that connects the supply flow path C2 and the air chamber (space that does not contain ink) of the subtank 151, and a head replacement valve V5 is disposed midway through the flow path. One end of the head replacement flow path C5 is connected to the upstream of the recording head 8 in the supply flow path C2 and connected to the downstream side of the supply valve V2. The other end of the head replacement flow path C5 is connected to the upper part of the subtank 151 and communicates with the air chamber inside the subtank 151. The head replacement flow path C5 is used when extracting ink from the recording head 8 in use, such as when replacing the recording head 8 or when transporting the recording device 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.

[0042] The cap unit 10 is connected to a flow path C6. A decompression pump P3 (in-cap decompression pump) is disposed in the flow path C6. The ink supply control unit 209 can drive the decompression pump P3 to generate negative pressure in the cap unit 10. A maintenance cartridge CA is disposed on the downstream side of the decompression pump P3 of the flow path C6 (the side opposite the cap unit 10). The maintenance cartridge CA holds the ink discharged through the flow path C6.

[0043] Next, the flow path configuration in the recording head 8 will be described. The ink supplied to the recording head 8 from the supply flow path C2 passes through a filter 83, and is then supplied to a first negative pressure control unit 81 and a second negative pressure control unit 82. The first negative pressure control unit 81 has a control pressure set to a weak negative pressure (negative pressure with a small pressure difference from atmospheric pressure). The second negative pressure control unit 82 has a control pressure set to a strong negative pressure (negative pressure with a large pressure difference from atmospheric pressure). The pressures in the first negative pressure control unit 81 and the second negative pressure control unit 82 are generated within an appropriate range by driving the recovery pump P2.

[0044] In the ink ejection section 80, a plurality of recording element substrates 80a, each having a plurality of ejection ports arranged therein, are arranged to form a long ejection port array. A common supply flow path 80b (IN flow path) for guiding ink supplied from the first negative pressure control unit 81 and a common recovery flow path 80c (OUT flow path) for guiding ink supplied from the second negative pressure control unit 82 also extend in the arrangement direction of the recording element substrates 80a. Furthermore, in each recording element substrate 80a, an individual supply flow path connected to the common supply flow path 80b and an individual recovery flow path connected to the common recovery flow path 80c are formed. Therefore, in each recording element substrate 80a, a flow of ink is generated in which ink flows in from the common supply flow path 80b, which has a relatively weak negative pressure, and flows out to the common recovery flow path 80c, which has a relatively strong negative pressure. In the path between the individual supply flow paths and the individual recovery flow paths, a pressure chamber is provided which is connected to each ejection port and is filled with ink, and ink flows even in ejection ports and pressure chambers which are not performing printing. When an ejection operation is performed on the recording element substrate 80a, a portion of the ink moving from the common supply flow path 80b to the common recovery flow path 80c is consumed by being ejected from the ejection port, but the ink that is not ejected moves to the recovery flow path C4 via the common recovery flow path 80c.

[0045] Fig. 6(a) is a schematic plan view of an enlarged portion of the recording element substrate 80a, and Fig. 6(b) is a schematic cross-sectional view taken along the cross-sectional line VIb-VIb in Fig. 6(a). The recording element substrate 80a is provided with pressure chambers 1005 filled with ink and ejection ports 1006 for ejecting ink. In the pressure chambers 1005, recording elements 1004 are provided at positions facing the ejection ports 1006. In addition, the recording element substrate 80a is provided with a plurality of individual supply flow paths 1008 connected to the common supply flow path 80b and individual recovery flow paths 1009 connected to the common recovery flow path 80c, each for each ejection port 1006.

[0046] With the above-mentioned configuration, in the recording element substrate 80a, a flow of ink is generated in which the ink flows in through the common supply flow path 80b, which has a relatively weak negative pressure (high absolute pressure value), and flows out to the common recovery flow path 80c, which has a relatively strong negative pressure (low absolute pressure value). More specifically, the ink flows in the order of the common supply flow path 80b → individual supply flow path 1008 → pressure chamber 1005 → individual recovery flow path 1009 → common recovery flow path 80c. When ink is ejected by the recording element 1004, a part of the ink moving from the common supply flow path 80b to the common recovery flow path 80c is ejected from the ejection port 1006 and discharged to the outside of the recording head 8. On the other hand, the ink not ejected from the ejection port 1006 is recovered to the recovery flow path C4 via the common recovery flow path 80c.

[0047] When performing a recording operation with the above configuration, 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. This establishes a circulation path from the subtank 151 to the supply flow path C2 to the recording head 8 to the recovery flow path C4 to the subtank 151. When the amount of ink supplied per unit time from the supply pump P1 is greater than the sum of the amount of ink discharged per unit time from the recording head 8 and the flow rate per unit time in the recovery pump P2, ink flows from the supply flow path C2 to the relief flow path C3. This adjusts the flow rate of ink flowing from the supply flow path C2 to the recording head 8.

[0048] When no printing operation is 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. This stops the flow of ink in the print head 8, and also suppresses backflow due to the head difference between the subtank 151 and the print head 8. Closing the atmosphere release valve V0 also suppresses ink leakage from the subtank 151 and ink evaporation.

[0049] <Ink stirring and degassing> The operation of stirring and degassing the ink filled in the subtank 151, which is a liquid container, will be described. The ink filled in the subtank 151 settles over time. When a predetermined time has passed since ink was supplied from the main tank 141 to the subtank 151, the ink in the subtank 151 has a high concentration at the bottom and a low concentration on the liquid surface side. In this state, when ink is supplied from the subtank 151 to the recording head 8, the supply flow path C2 is connected to the bottom side of the subtank 151, so that ink with a high concentration is supplied to the recording head 8. Therefore, the color of the image on the recording medium is dark at the beginning of recording, and becomes lighter as the ink in the subtank is consumed. To solve this problem, the ink in the subtank 151 is stirred by a stirring mechanism. As a result, it is possible to prevent the ink concentration in the subtank 151 from affecting the color of the image on the recording medium.

[0050] In addition, oxygen dissolves in the ink supplied to the subtank 151 over time, in an amount equal to the saturated dissolved oxygen amount of the ink. Ink with a certain amount of dissolved oxygen generates air bubbles in the flow path. When the flow path is blocked by air bubbles, the ink becomes difficult to flow. As a result, ink cannot be ejected from the ejection port 1006 of the recording head 8. Therefore, a degassing operation must be performed to remove the dissolved oxygen from the ink in the subtank 151. In this embodiment, an operation of simultaneously performing stirring and degassing will be described.

[0051] First, the stirring mechanism and the stirring operation will be described. Figures 7, 8, and 9 show one color portion (500) of the stirring mechanism. Figure 8 shows the stirring mechanism 500 from above, and Figure 9 shows a perspective view of the cross section taken along the cutting line D1 in Figure 8 to show the inside of the subtank 151. The stirring mechanism 500 is composed of the subtank 151, a stirrer 501 arranged with a gap under the bottom of the subtank 151, a stirrer 502 arranged on the bottom of the subtank 151, and a stirring drive mechanism 503 that rotates the stirrer 501. The stirrer 502 is placed on the bottom of the subtank 151 as shown in Figure 9. Therefore, there is no positioning structure such as a pivot support from the subtank 151. Figure 10 shows a cross section taken along the cutting line D2 in Figure 8. The stirrer 151 has a stirrer magnet 502A inside a cylindrical rod-shaped body. Plastic resin covers the stirrer magnet 502A to form the outer shape. The rod-shaped body may be a polygonal prism rather than a cylinder, and may be a cylinder whose cross-sectional area becomes wider from the longitudinal ends toward the center.

[0052] Stirrer 501 has pulley 505, which is a rotating body that holds two stirrer magnets (504A, 504B). Pulley 505 is supported by pulley shaft 506, which is a rotating shaft, and rotates around pulley shaft 506. Pulley 505 is connected by stirring belt 507, which is connected to stirring gear 508. Stirring gear 508 is further connected to stirring motor 509. In other words, when stirring motor 509 is operated, pulley 505 rotates, and stirrer magnet 504 attached to pulley 505 rotates on the rotating shaft. Stirrer magnet 504B has an N pole on the upper side (subtank 151 side) facing the bottom of subtank 151, and stirrer magnet 504A has an S pole on the upper side. Stirrer magnet 502A is a rod-shaped body with one end in the longitudinal direction as the N pole and the other end as the S pole. Therefore, when pulley 505 is stopped, the south pole side of stirrer bar 502 is attracted to the north pole side of stirrer magnet 504, and the north pole side of stirrer bar 502 is attracted to the south pole side of stirrer magnet 504, stabilizing the position. When stirring motor 509 is operated from this state to rotate pulley 505, which is a rotating body, stirrer bar 502 also rotates along with stirrer magnet 504. The rotating stirrer 502 generates a flow that rotates the ink in subtank 151. In this way, the ink is stirred, mixing the high-concentration ink that has settled to the bottom of subtank 151 with the low-concentration ink on the liquid surface side.

[0053] Next, the degassing operation will be described. The degassing operation is performed by reducing the pressure inside the subtank 151 in addition to the stirring operation described above. The degassing operation of the ink supply unit 15 will be described with reference to the flow chart in FIG. 16. First, the air release valve V0, the tank supply valve V1, the supply valve V2, and the recovery valve V4 are closed, and the subtank pressure reducing valve V6 is opened. Next, the pressure reducing pump P0 is operated to create a negative pressure inside the subtank 151. The subtank 151 is kept on standby until a predetermined negative pressure is reached, and then the pressure reducing pump P0 is stopped. When the gas inside the subtank 151 becomes negative pressure, the amount of oxygen dissolved in the ink is reduced and the ink is degassed. To further increase the degassing efficiency, the stirring operation described above is performed with the subtank 151 under negative pressure. The stirring motor 509 is operated and waited for a predetermined time, and then the stirring motor 509 is stopped. The predetermined time refers to the time required for stirring and degassing the ink. The principle of degassing with this operation is that when the stirring motor 509 is operated and the stirrer 502 is rotated, air bubbles are generated in the ink by cavitation. If air bubbles generated by cavitation remain in the ink after the stirring operation has stopped, they will dissolve in the ink again. On the other hand, if the air bubbles rise to the liquid level E (Figure 10) before dissolving in the ink and disappear, they will be separated from the ink and the ink in the subtank 151 will be degassed. Once the degassing operation is complete, the atmosphere release valve V0 is opened and the system waits for a predetermined time until the negative pressure in the subtank 151 is released. Once the negative pressure has been released, the atmosphere release valve V0 and the subtank pressure reducing valve V6 are closed and the operation ends. The degassing operation is performed at a time set in the main unit, and is usually performed once a day. The operator sets the time to perform the degassing operation using the buttons on the operation panel 104.

[0054] Here, a specific shape of the stirrer 502 will be described. The stirrer 502 has a stirrer magnet 502A inside the plastic resin. The positions of both ends in the longitudinal direction of the stirrer magnet 502A are at a length that positions them at the center of the stirrer magnet 504 (FIG. 10). That is, the end on the side of the blade 502B1 is the N pole and is located at the center of the stirrer magnet 504, which is the S pole. The end on the side of the blade 502B2 is the S pole and is located at the center of the stirrer magnet 504, which is the N pole. The positions of both ends may be positions where the magnetic force is strong at both ends. If the end of the stirrer magnet 502A is located at a position shifted from the center 504a of the stirrer magnet 504, one side of the end of the stirrer magnet 502A is attracted to the part of the stirrer magnet 504 where the magnetic force is strong (here, the center 504a of the stirrer magnet 504). As a result, the center of the stirrer 502 is shifted from the center position of the pulley 505. Then, the stirrer 502 cannot rotate around the rotation axis 502D at the center in the longitudinal direction when rotating. The stirrer 502 becomes difficult to rotate following the stirrer magnet 504 and loses synchronization. In other words, by positioning the end of the stirrer magnet 502A at the center 504a of the stirrer magnet 504, it is possible to suppress the stirrer 502 from losing synchronization during stirring. As a result, it is possible to increase the rotation speed of the stirrer 501, which has the effect of shortening the operation time for stirring and degassing the liquid. The stirrer magnet 502A may be arranged separately so that magnetic forces are generated at both ends in the longitudinal direction, rather than being integrated.

[0055] Both ends of the stirrer 502 are plate-shaped blades 502B having flat surfaces extending in the longitudinal direction. The plate-shaped blades may have curved surfaces. FIG. 11 is a diagram showing the inside of the subtank 151 as seen from the cutting line D3 in FIG. 7, and the direction in which the stirrer 502 rotates during the stirring operation is the R direction, which is the circumferential direction of the rotation axis of the pulley shown by the arrow. FIG. 12 is a side view of the end of the stirrer 502 as seen from the direction of the arrow E in FIG. 11. The blade 502B is on the inside of the cross section of the rod-shaped body in a plane perpendicular to the longitudinal direction of the rod-shaped body. Being on the inside does not interfere with the rotation of the stirrer 502. The rotation direction of the blade 502B at the end of the stirrer 502 is the R direction on the right side as shown in FIG. 12, and the stirrer 502 rotates with the longitudinal center of the rod-shaped body as a fulcrum. The blade 502B is inclined at an angle θ counterclockwise with respect to the vertical direction in a plane perpendicular to the longitudinal direction (FIG. 12). That is, as shown in FIG. 13, the side 502B1b of the blade 502B1 close to the bottom is the leading end side in the rotation direction, and the side 502B1a far from the bottom is the trailing end side in the rotation direction. Similarly, the side 502B2b of the blade 502B2 close to the bottom is the leading end side in the rotation direction, and the side 502B2a far from the bottom is the trailing end side in the rotation direction. In addition, the blade 502B2 at the end and the blade 502B1 at the opposite end are line-symmetrical with respect to the vertical axis in FIG. 12 as the axis of symmetry. By having such an axis of symmetry, the stirrer 502 can rotate stably. The blade 502B1 and the blade 502B2 may be point-symmetrical with respect to the longitudinal axis.

[0056] When the stirrer 502 rotates in the R direction, the ink in the subtank 151 receives a force from the stirrer 151 and is stirred. At that time, the blade 502B tilts at an angle θ and rotates from the tip side 502B2b, making it possible to stir the ink in the U direction shown in FIG. 12. In other words, a flow of ink can be generated that sends ink from the bottom of the subtank 151 to the liquid surface side. This not only improves the ink stirring efficiency, but also makes it possible to send air bubbles generated by the blade 502B to the liquid surface E and eliminate the bubbles. As a result, it becomes possible to improve the degassing efficiency.

[0057] When comparing the angle θ of the blade 502B with 0 degrees, 30 degrees, 45 degrees, and 60 degrees, the angle with the best degassing efficiency is 45 degrees as shown in FIG. 12. The degassing efficiency is determined by the amount of bubbles generated by cavitation and the flow of ink that sends the bubbles onto the liquid surface E. The amount of bubbles generated increases in the order of 0 degrees > 30 degrees > 45 degrees > 60 degrees. This is because the larger the cross-sectional area of ​​the blade 502B in the rotation direction, the more likely cavitation is to occur. In other words, as the angle θ increases, the cross-sectional area of ​​the blade 502B becomes narrower and cavitation becomes less likely to occur. FIG. 14 shows data showing the amount of bubbles generated by cavitation per one rotation of the stirrer 502 by simulation. On the other hand, the ease of sending bubbles onto the liquid surface E is in the order of 60 degrees > 45 degrees > 30 degrees > 0 degrees, because the direction of U shown in FIG. 12 becomes closer to the vertical direction as the angle θ increases. A simulation of the amount of air bubbles sent onto the liquid level E per rotation of the stirrer 502 is shown in Figure 15. The amount of air bubbles sent onto the liquid level E increases in the following order: 45 degrees > 0 degrees ≒ 30 degrees > 60 degrees. Therefore, the angle that provides the best degassing efficiency among these is 45 degrees. Note that a manufacturing error of several degrees is allowed for 45 degrees. The optimal angle will vary depending on the rotation speed of the stirrer 502, the size of the subtank 151 and stirrer 502, the height of the ink liquid level E, and other factors.

[0058] The stirrer 502 is simply placed inside the subtank 151 without being positioned relative to it. If the stirrer 502 is a cylinder, it rotates in the circumferential direction, and the angle of the blades 502B is not stable. On the other hand, if the stirrer 502 is a rectangular column, the posture is stabilized with each flat surface as the bottom surface, and the angle of the blades 502B may not be a specified angle. For this reason, the stirrer 502 has a rotation restriction part 502C at the center of the longitudinal direction to restrict the rotation in the circumferential direction. The rotation restriction part 502C has a shape with a horizontal long side C1 (about 13 mm) and a vertical short side C2 (about 8 mm) of a plane perpendicular to the longitudinal direction, and the outer peripheral surface C1a of the long side is curved (FIG. 13). It is desirable that the curvature of C1a is as large as possible. The reason is that when the center of the stirrer magnet 502A and the center of the plastic resin covering the outside are molded out of alignment, the stirrer 502 rotates in the circumferential direction by the amount that the center of gravity is offset from the center, and the posture is stabilized. By reducing the amount of rotation of the stirrer 502 in the circumferential direction, the angle θ can be kept close to a predetermined angle. On the other hand, if the curvature is increased, the long side C1 becomes longer and the stirrer 502 becomes larger. These lengths need to be set appropriately in consideration of the size of the sub-tank 151, etc. In addition, C2a, which is the tip of the long side C1, is also curved to prevent C2a from becoming the bottom surface. By providing the rotation restriction part 502C at the center of the stirrer 502 in this way, it is possible to keep the angle θ of the blade 502B at approximately a predetermined angle even if the stirrer 502 is not positioned relative to the sub-tank 151. In this embodiment, the length of the stirrer magnet 502A is about 20 mm, the height of the stirrer magnet 504 in the vertical direction is about 3 mm, the cross section is about 10 mm x about 10 mm, and the inner diameter of the sub-tank 151 is about φ50 mm.

[0059] Here, the stirring operation speed and the stirring and degassing operation time will be described. In the conventional configuration, the rotation speed of the stirrer 501 is about 800 rpm, and if the rotation speed is increased above that, the stirrer 502 may lose synchronization. In contrast, in the configuration of this embodiment in which the end of the stirrer magnet 502A is positioned at the center 504a of the stirrer magnet 504, the stirring rotation speed can be about 1000 rpm. In addition, the time required for the stirring and degassing operations is about 320 seconds from start to finish in the conventional configuration according to the flowchart described in FIG. 16. By providing the stirrer 502 with the blade 502B and the rotation restriction part 502C, the operation time can be shortened to about 220 seconds. Furthermore, if the rotation speed of the stirrer 501 described above is set to about 1000 rpm, the operation time can be shortened to about 150 seconds.

[0060] As described above, the stirring bar 502, which is a rod-shaped body with blades at both longitudinal ends, can improve the stirring efficiency of the liquid with a simple structure. Also, in a stirring device and a recording device in which the stirring bar 502 of this embodiment is placed in the sub-tank 151, the stirring efficiency and degassing efficiency of the ink can be improved. [Explanation of symbols]

[0061] 151 Subtank 500 Mixing mechanism 501 Stirrer 502 Stirring bar 502B Feather 504 Stirrer Magnet 505 Pulley

Claims

1. a rod-shaped body having a cylindrical shape and a first end and a second end opposite to the first end in a longitudinal direction, the first end and the second end having magnetic force, a restricting portion extending on both sides of the rod-shaped body in a first direction in a plane perpendicular to the longitudinal direction and restricting rotation of the rod-shaped body relative to a circumferential direction of the longitudinal direction; a plate-shaped first blade extending in the longitudinal direction from the first end and having a first front surface and a first back surface; a plate-shaped second blade extending from the second end in the longitudinal direction and having a second front surface and a second back surface, A stirrer characterized in that, when viewed from the longitudinal direction, the first surface and the second surface are linearly symmetrical with respect to a second direction perpendicular to the first direction and inclined with respect to the first direction, and the first back surface and the second back surface are linearly symmetrical with respect to the second direction and inclined with respect to the first direction.

2. The stirrer described in claim 1, characterized in that, when viewed from the longitudinal direction, the first front surface and the first back surface intersect with the second direction at 45 degrees, and the second front surface and the second back surface intersect with the second direction at -45 degrees.

3. The stirrer according to claim 1 or 2, wherein a length of the restricting portion in the first direction is longer than a length of the restricting portion in the second direction.

4. 4. The stirrer according to claim 1, wherein the first blade and the second blade are located inside a cross section of the rod-shaped body when viewed from the longitudinal direction.

5. 5. The stirrer according to claim 1, wherein a tip of the restriction portion in the first direction is a curved surface that is line-symmetric with respect to the first direction.

6. The stirrer according to claim 5 , wherein a curvature of the restricting portion in the second direction is greater than a curvature of the curved surface.

7. The stirrer according to any one of claims 1 to 6, A liquid container in which the stirring bar is placed without being positioned and which contains liquid; a rotor that rotates on a rotation axis facing downward at the bottom of the liquid container and has magnets at multiple positions.

8. The stirring device according to claim 7, characterized in that the tip side of the first blade and the second blade when rotating in the circumferential direction of the rotation axis of the stirrer is closer to the bottom of the liquid container than the rear end side.

9. The stirring device according to claim 8, characterized in that, when viewed from the longitudinal direction, the first blade intersects with the rotation axis at 45 degrees, and the second blade intersects with the rotation axis at -45 degrees.

10. The stirring device described in any one of claims 7 to 9, characterized in that the multiple magnets are a first magnet with its north pole facing the bottom and a second magnet with its south pole facing the bottom, and the first end is located at the center of the first magnet and the second end is located at the center of the second magnet.

11. The stirring device according to any one of claims 7 to 10, A recording head for recording an image on a recording medium; an ink jet recording apparatus comprising: a flow path connecting said recording head and said liquid container; and said liquid being ink to be supplied to said recording head.

12. 12. The inkjet recording apparatus according to claim 11, wherein the liquid container is provided with a pump for reducing pressure to degas the liquid.

13. 13. The ink jet recording apparatus according to claim 11, wherein the rotating body is rotated after the liquid container is decompressed.

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