Recording device and recording method

Abstract

Improved ink heating efficiency. [Solution] The recording device comprises a discharge head, a circulation path that guides liquid to a discharge port provided in the discharge head and circulates the liquid so as to guide any liquid that is not discharged from the discharge port back to the discharge port, a heating means for heating the liquid flowing through the circulation path, a circulation means disposed inside the discharge head for circulating the liquid in the circulation path at a flow rate according to a setting, and an adjustment means for adjusting the flow rate of the liquid flowing through the circulation path by controlling the setting of the circulation means. The heating means starts heating before the recording operation to the recording medium is performed, and the adjustment means slows down the flow rate of the liquid flowing through the circulation path before the recording operation is performed compared to the flow rate of the liquid flowing through the circulation path while the recording operation is performed.

Description

Technical Field

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[0001] ,

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[0001] The present disclosure relates to a technique for improving the heating efficiency of ink.

Background Art

[0002] Patent Document 1 discloses an inkjet printer including an ink head, an upstream tank, a downstream tank, and an ink circulation path. The upstream tank supplies ink to the ink head. Ink that has not been ejected from the ink head is discharged to the downstream tank. The ink circulation path connects the upstream tank and the downstream tank to circulate the ink. In this inkjet printer, the amount of circulating ink is changed according to the temperature of the circulating ink in the ink circulation path.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] According to this disclosure, the heating efficiency of the ink can be improved. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of the configuration of a recording device. [Figure 2] This is a perspective view showing an example of a discharge head. [Figure 3] This is a cross-sectional view showing an example of a discharge unit. [Figure 4] This is a schematic diagram showing the configuration of the circulation unit. [Figure 5] This is a diagram showing the configuration of the first pressure adjustment unit. [Figure 6] This is a block diagram showing the configuration of the control system installed in the recording device. [Figure 7] This graph shows the relationship between the rotation speed setting of the circulation pump and time. [Figure 8] This flowchart shows an example of a recording process performed in a recording device. [Figure 9] This graph shows the relationship between the flow velocity of ink through a circulation path and time. [Figure 10]This flowchart shows an example of the recording process performed in the second embodiment. [Figure 11] This flowchart shows an example of the recording process performed in the third embodiment. [Figure 12] This figure shows an example of a discharge unit having relatively different discharge ports. [Modes for carrying out the invention]

[0008] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings. The following embodiments are not limiting to the scope of this disclosure, and not all combinations of features described in the following embodiments are essential to the solutions of this disclosure. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0009] <First Embodiment> <<overview>> In recording devices, pre-recording operations require time between receiving a recording command and starting the recording operation. From the user's perspective, a shorter time between receiving a recording command and starting the recording operation is preferable. In recent years, recording devices equipped with a circulation path for circulating ink have appeared. This is to suppress the increase in ink viscosity due to drying from the nozzle and to suppress ejection failures. However, circulating the ink can reduce the ink heating efficiency, which may affect the time between receiving a recording command and starting the recording operation. The following explains an example of improving ink heating efficiency with reference to the diagram. In the referenced diagram, the X, Y, and Z directions are defined. The X and Y directions are orthogonal to each other. The Z direction is orthogonal to the XY plane.

[0010] <<Recording device>> FIG. 1 is a diagram showing an example of the configuration of a recording apparatus 10. The recording apparatus 10 is an inkjet recording apparatus that scans a discharge head 11 and discharges ink to perform recording on a recording medium 12. The recording apparatus 10 forms an image on the recording medium 12 by repeating a recording operation and a conveyance operation. The recording operation is an operation of discharging ink while moving the discharge head 11 in the main scanning direction. The conveyance operation is an operation of conveying the recording medium 12 in the sub-scanning direction. The main scanning direction and the sub-scanning direction intersect. In the example of FIG. 1, the main scanning direction is the X direction, and the sub-scanning direction is the Y direction. The Z direction may be the vertical direction.

[0011] The ink is a liquid that can be used to form an image, pattern, pattern, etc. by being applied to the recording medium 12. The recording medium 12 is a medium that can receive ink. Generally, the recording medium 12 is paper, but it is not limited thereto. For example, the recording medium 12 may be a plastic film, a metal plate, glass, ceramics, wood, leather, or the like. The recording medium 12 is conveyed in the sub-scanning direction by conveyance rollers 13, 14, 15, and 16.

[0012] The recording apparatus 10 is provided with an ink tank 17 and an external pump 18. The ink tank 17 is a supply source of the ink supplied to the discharge head 11. Ink is stored in the ink tank 17. The external pump 18 supplies the ink stored in the ink tank 17 to the discharge head 11 via an ink supply tube 19.

[0013] The recording apparatus 10 is provided with a cap member 20. The cap member 20 is used for preventing drying of the discharge port of the discharge head 11. The cap member 20 closes the discharge port of the discharge head 11 during a non-recording operation. During the non-recording operation, the discharge head 11 is disposed at a position deviated from the conveyance path of the recording medium 12.

[0014] The ejection head 11 is mounted on the carriage 21. The carriage 21 is provided with fixing means for fixing the ejection head 11 and electrical contacts electrically connected to the ejection head 11 fixed to the fixing means. The user can operate the fixing means to remove the ejection head 11 from the carriage 21. Also, the user can operate the fixing means to attach the ejection head 11 to the carriage 21. The carriage 21 is attached to the guide shaft 22 so as to be movable along the guide shaft 22. The guide shaft 22 is arranged along the main scanning direction. The ejection head 11 mounted on the carriage 21 can reciprocate in the main scanning direction along the guide shaft 22.

[0015] 〈〈Ejection Head〉〉 FIG. 2 is a perspective view showing an example of the ejection head 11. The ejection head 11 is a member capable of ejecting ink. The ejection head 11 includes a head housing 23, a plurality of ink inlets 24, an ejection unit 25, and a plurality of circulation units 26. The plurality of circulation units 26 are housed in the head housing 23. Each ink inlet 24 is provided corresponding to one circulation unit 26. The ink introduced from each ink inlet 24 is supplied to the corresponding circulation unit 26 without mixing with each other. The ejection unit 25 is a unit for ejecting ink onto the recording medium 12. The circulation unit 26 is a unit for circulating ink. The ejection unit 25 and the circulation unit 26 are connected.

[0016] Ink is supplied to each ink inlet 24 through an external supply path. The external supply path is a path from the ink supply source to the ejection head 11 and is provided outside the ejection head 11. The external supply path includes an ink tank 17 (FIG. 1), an external pump 18 (FIG. 1), and an ink supply tube 19 (FIG. 1). One end of the ink supply tube 19 is connected to the ink inlet 24. The external supply path is provided independently for each ink inlet 24. The ink flowing through each independently provided external supply path does not mix with each other.

[0017] In this embodiment, the discharge head 11 is capable of dispensing multiple types of ink. Specifically, one of the multiple ink inlets 24 is an ink inlet 24B for black ink. The circulation unit 26 corresponding to the ink inlet 24B for black ink is a circulation unit 26B for black ink. Black ink that flows into the ink inlet 24B via an external supply path is supplied to the circulation unit 26B. A portion of the black ink supplied to the circulation unit 26B is discharged from the discharge unit 25.

[0018] In this embodiment, one of the multiple ink inlets 24 is an ink inlet 24C for cyan ink. The circulation unit 26 corresponding to the cyan ink inlet 24C is a cyan ink circulation unit 26C. Cyan ink that flows into the ink inlet 24C via an external supply path is supplied to the circulation unit 26C. A portion of the cyan ink supplied to the circulation unit 26C is discharged from the discharge unit 25.

[0019] In this embodiment, one of the multiple ink inlets 24 is an ink inlet 24M for magenta ink. The circulation unit 26 corresponding to the ink inlet 24M for magenta ink is a circulation unit 26M for magenta ink. Magenta ink that flows into the ink inlet 24M via an external supply path is supplied to the circulation unit 26M. A portion of the magenta ink supplied to the circulation unit 26M is discharged from the discharge unit 25.

[0020] In this embodiment, one of the multiple ink inlets 24 is an ink inlet 24Y for yellow ink. The circulation unit 26 corresponding to the ink inlet 24Y for yellow ink is a circulation unit 26Y for yellow ink. Yellow ink that flows into the ink inlet 24Y via an external supply path is supplied to the circulation unit 26Y. A portion of the yellow ink supplied to the circulation unit 26Y is discharged from the discharge unit 25.

[0021] <<Discharge Unit>> Figure 3 is a cross-sectional view showing an example of a discharge unit 25. The discharge unit 25 comprises a silicon substrate 31, a discharge port forming member 32, and a plurality of discharge elements 33. The silicon substrate 31 has a plurality of supply channels 34, a plurality of recovery channels 35, a plurality of supply connection channels 36, and a plurality of recovery connection channels 37 formed therein.

[0022] The discharge port forming member 32 is provided on one side (the bottom surface in Figure 3(b)) of the silicon substrate 31. The discharge port forming member 32 has a plurality of pressure chambers 38 and a plurality of discharge ports 39 formed therein.

[0023] Each ejection element 33 is composed of an electrothermal conversion element (ejection heater) that generates thermal energy as ejection energy for ejecting ink. Power is supplied to each ejection element 33 via electrical wiring. The electrical wiring is provided on the silicon substrate 31 by thin-film deposition technology or the like. Each ejection element 33 generates thermal energy by the power supplied via the electrical wiring.

[0024] Each discharge element 33 is provided on one side of the silicon substrate 31. This one side of the silicon substrate 31 is in contact with a portion of each pressure chamber 38 formed in the discharge port forming member 32. At least one discharge element 33 is arranged corresponding to each pressure chamber 38. In the example in Figure 3, one discharge element 33 is arranged corresponding to each pressure chamber 38. A row of discharge ports 40 is arranged in one pressure chamber 38. Specifically, one discharge element 33 is arranged on the side of the wall surrounding one pressure chamber 38 that faces the portion where the row of discharge ports 40 is located.

[0025] The discharge port row 40 is a row of discharge ports 39 arranged at intervals along the Y direction. The number of discharge ports 39 formed in the discharge port forming member 32 is the sum of the number of discharge ports 39 that form the discharge port row 40 located in each pressure chamber 38.

[0026] Each pressure chamber 38 is in communication with a supply channel 34 via a supply connection channel 36. Each pressure chamber 38 is in communication with a recovery channel 35 via a recovery connection channel 37. The supply channel 34 and recovery channel 35 that are in communication with one pressure chamber 38 are in communication with one of the multiple circulation units 26.

[0027] Ink is supplied to the supply channel 34 from the circulation unit 26. The ink supplied to the supply channel 34 flows into the pressure chamber 38 via the supply connection channel 36. A portion of the ink that flows into the pressure chamber 38 is discharged from the discharge ports 39 that form the discharge port row 40 by the driving (heat generation) of the discharge element 33. The ink that is not discharged from the discharge ports 39 that form the discharge port row 40 flows out into the recovery channel 35 via the recovery connection channel 37. The ink that flows out into the recovery channel 35 is supplied to the circulation unit 26.

[0028] In this manner, the discharge unit 25 has one circulation unit 26 connected to each pressure chamber 38, and ink can be discharged from the discharge port 39 of each pressure chamber 38. In this embodiment, for example, black ink can be discharged from the discharge port 39 of the leftmost pressure chamber 38 in the figure. Cyan ink can be discharged from the discharge port 39 of the second pressure chamber 38 from the left in the figure. Magenta ink can be discharged from the discharge port 39 of the third pressure chamber 38 from the left in the figure. Yellow ink can be discharged from the discharge port 39 of the fourth pressure chamber 38 from the left in the figure.

[0029] <<Circulation Unit>> Multiple circulation units 26 each have substantially the same configuration. Therefore, the following description will focus on one circulation unit 26. Figure 4 is a schematic diagram including the configuration of the circulation unit 26. The circulation unit 26 is equipped with a filter 43, a first pressure adjustment unit 44, a second pressure adjustment unit 45, and a circulation pump 46.

[0030] The filter 43 removes foreign matter such as dust and air bubbles contained in the ink. The filter 43 is connected to the ink inlet 24 (Figure 2) via the input upstream channel 47. The filter 43 is also connected to the first pressure adjustment unit 44 via the input downstream channel 48.

[0031] The first pressure adjustment unit 44 has a first valve chamber 441 and a first pressure control chamber 442. The downstream end of the input downstream passage 48 is connected to the first valve chamber 441. The first valve chamber 441 and the first pressure control chamber 442 are in communication with each other via a first communication port 443. The first communication port 443 is opened and closed by a first valve 444. The first pressure control chamber 442 is connected to the supply passage 34 of the discharge unit 25 via a supply passage 49 and is in communication with the pressure chamber 38. The first pressure control chamber 442 is also connected to the second pressure adjustment unit 45 via a bypass passage 50. Furthermore, the first pressure control chamber 442 is connected to the circulation pump 46 via a pump outlet passage 51. In the example of Figure 4, the upstream end of the bypass passage 50 is connected to the first pressure control chamber 442, but it may also be connected to the supply passage 49.

[0032] The second pressure adjustment unit 45 has a second valve chamber 451 and a second pressure control chamber 452. The downstream end of the bypass passage 50 is connected to the second valve chamber 451. The second valve chamber 451 and the second pressure control chamber 452 are in communication with each other via a second communication port 453. The second communication port 453 is opened and closed by a second valve 454. The second pressure control chamber 452 is connected to the recovery passage 35 of the discharge unit 25 via a recovery passage 52 and is in communication with the pressure chamber 38. The second pressure control chamber 452 is also connected to the circulation pump 46 via a pump inlet passage 53.

[0033] The circulation pump 46 performs an ink supply operation at an amount (pressure) corresponding to the set pump rotation speed. The ink supply operation involves drawing ink from the pump inlet passage 53 and sending the drawn ink to the pump outlet passage 51.

[0034] <Pressure adjustment section> The first pressure adjustment unit 44 and the second pressure adjustment unit 45 described above have substantially the same configuration. Therefore, the first pressure adjustment unit 44 will be described below with reference to Figures 5(a) and 5(b). Figure 5(a) shows the configuration of the first pressure adjustment unit 44 in the closed state. Figure 5(b) shows the configuration of the first pressure adjustment unit 44 in the open state. In Figures 5(a) and 5(b), the reference numerals indicating the components of the second pressure adjustment unit 45 that correspond to the components of the first pressure adjustment unit 44 are shown in parentheses.

[0035] The first pressure regulating unit 44 has a cylindrical housing 55. A partition wall 56 is provided inside the housing 55. This partition wall 56 separates the inside of the housing 55 into a first valve chamber 441 and a first pressure control chamber 442. A first communication port 443 is formed in the partition wall 56. The first communication port 443 penetrates the partition wall 56. The first valve chamber 441 and the first pressure control chamber 442 are in communication through this first communication port 443.

[0036] A first valve 444 is provided in the first valve chamber 441. A valve spring 57 is attached to the first valve 444. The first valve 444 closes the first communication port 443 by the biasing force of the valve spring 57. A valve shaft 58 is provided in the first valve 444. The valve shaft 58 protrudes from the first valve 444 through the first communication port 443 into the first pressure control chamber 442.

[0037] The opening of the cylindrical housing 55 is closed by a flexible member 59 and a pressure plate 60. The flexible member 59, the pressure plate 60, the peripheral wall of the housing 55, and the partition wall 56 form the first pressure control chamber 442. The pressure plate 60 is configured to be displaceable in accordance with the displacement of the flexible member 59.

[0038] A pressure regulating spring 61 is provided between the pressure plate 60 and the partition wall 56. The biasing force of this pressure regulating spring 61 biases the pressure plate 60 and the flexible member 59 in a direction that expands the volume of the first pressure control chamber 442, as shown in Figure 5(a). Furthermore, when the pressure in the first pressure control chamber 442 decreases, the pressure plate 60 and the flexible member 59 are displaced against the pressure of the pressure regulating spring 61 in a direction that decreases the volume of the first pressure control chamber 442. When the volume of the first pressure control chamber 442 decreases to a predetermined value, the pressure plate 60 comes into contact with the valve shaft 58 of the first valve 444. Subsequently, as the volume of the first pressure control chamber 442 decreases further, the first valve 444 moves together with the valve shaft 58 against the biasing force of the valve spring 200, as shown in Figure 5(b), and moves away from the partition wall 56. In this state, the flow of ink between the first valve chamber 441 and the first pressure control chamber 442 is opened.

[0039] In this embodiment, the pressure in the first valve chamber 441 when the first communication port 443 is open and separated from the partition wall 56 is set higher than the pressure in the first pressure control chamber 442. Therefore, when the first communication port 443 is open, ink flows from the first valve chamber 441 into the first pressure control chamber 442. This ink inflow causes the flexible member 59 and the pressure plate 60 to displace in a direction that increases the volume of the first pressure control chamber 442. As a result, the pressure plate 60 separates from the valve shaft 58 of the first valve 444, and the first valve 444 comes into contact with the partition wall 56 due to the biasing force of the valve spring 57. In this state, the flow of ink between the first valve chamber 441 and the first pressure control chamber 442 is blocked.

[0040] Thus, in the first pressure adjustment unit 44, when the pressure in the first pressure control chamber 442 decreases to below a certain pressure (for example, when the negative pressure becomes strong), ink flows in from the first valve chamber 441 through the first communication port 443. Therefore, the pressure in the first pressure control chamber 442 is controlled to be maintained within a certain range.

[0041] Furthermore, the first pressure adjustment unit 44 is configured to have a relatively higher control pressure than the second pressure adjustment unit 45. The pressure difference between the first pressure adjustment unit 44 and the second pressure adjustment unit 45 allows ink to flow through the circulation path 500 (Figure 4) even if the ink supply operation of the circulation pump 46 stops.

[0042] <Circulation pathway> The circulation path 500 will be explained with reference to Figure 4. The circulation path 500 is a path that circulates the ink so that it guides the ink to the discharge port 39 and guides any ink that was not discharged from the discharge port 39 back to the discharge port 39. The circulation path 500 is formed inside the discharge head 11 by the discharge unit 25 and the circulation unit 26.

[0043] In the circulation path 500, ink supplied from the external ink tank 17 (Figure 1) of the ejection head 11 circulates. The flow of ink up to the circulation path 500 will now be explained with reference to Figure 4. The arrows in Figure 4 indicate the direction of ink flow.

[0044] The ink stored in the ink tank 17 (Figure 1) is pressurized by the external pump 18 (Figure 1) and supplied to the ink inlet 24 (Figure 2). The ink supplied to the ink inlet 24 passes through the filter 43 via the input upstream channel 47. The ink that has passed through the filter 43 flows into the first valve chamber 441 via the input downstream channel 48. When the first valve 444 is open, the ink that has flowed into the first valve chamber 441 passes through the first communication port 443 and flows into the first pressure control chamber 442. Due to the pressure loss when passing through the communication port 191A, the ink that has flowed into the first pressure control chamber 442 switches from positive pressure to negative pressure. The ink that has flowed into the first pressure control chamber 442 circulates through the circulation path 500. In other words, the first pressure control chamber 442 is included as part of the circulation path 500.

[0045] When the circulation pump 46 performs the ink supply operation, the ink flows through the circulation path 500. The flow of ink in the circulation path 500 will now be explained with reference to Figure 4. The ink sent to the pump outlet passage 51 by the ink supply operation flows into the supply passage 49 and the bypass passage 50 together with the ink that has flowed into the first pressure control chamber 442.

[0046] The ink that flows into the supply channel 49 flows into the pressure chamber 38 via the supply channel 34 of the discharge unit 25. A portion of the ink that flows into the pressure chamber 38 is discharged from the discharge port 39 by the drive (heat generation) of the discharge element 33. The ink that is not discharged from the discharge port 39 flows into the recovery channel 52 of the circulation unit 26 via the recovery channel 35 of the discharge unit 25. The ink that flows into the recovery channel 52 of the circulation unit 26 flows into the second pressure control chamber 452 of the second pressure adjustment unit 45.

[0047] Meanwhile, the ink that flows into the bypass channel 50 flows into the second valve chamber 451. When the second valve 454 is open, the ink that has flowed into the second valve chamber 451 passes through the second communication port 453 and flows into the second pressure control chamber 452.

[0048] The ink that flows into the second pressure control chamber 452 via the bypass channel 50 and the ink recovered from the recovery channel 52 are drawn into the circulation pump 46 via the pump inlet channel 53 by the ink feeding operation of the circulation pump 46. The ink drawn into the circulation pump 46 is then sent back to the pump outlet channel 51.

[0049] In this way, the ink flows through the circulation path 500 formed inside the discharge head 11. Because the ink is flowing, the accumulation of sedimentary components of the ink in the pressure chamber 38 and other areas is suppressed. As a result, the ink discharge characteristics are maintained in a good state.

[0050] In this embodiment, the circulation path 500 is entirely contained within the ejection head 11. Furthermore, the circulation pump 46 included in the circulation path 500 is located inside the ejection head 11. Therefore, the circulation path length can be significantly shortened compared to the case where ink is circulated between an external ink tank 17 and the ejection head 11. As a result, the circulation pump 46 located inside the ejection head 11 can be miniaturized, enabling a smaller ejection head 11. In addition, the recording device 10 does not require an external recovery path to recover ink supplied to the circulation unit 26 outside the ejection head 11. Therefore, the recording device 10 can be configured simply. Furthermore, the external pump 18 (Figure 1) can also be miniaturized. Moreover, the tube included in the external recovery path becomes unnecessary. Therefore, it is possible to reduce ink pressure fluctuations caused by the oscillation of the tube accompanying the main scanning of the ejection head 11. In addition, the driving load on the carriage motor that drives the carriage 21 (Figure 1), caused by the oscillation of the tube, can be reduced.

[0051] <<Control system for recording device>> Figure 6 is a block diagram showing the configuration of the control system mounted on the recording device 10. The recording device 10 includes a CPU 65, a ROM 66, and a RAM 67. The CPU 65 is a processor (arithmetic unit) that controls the operation of the recording device 10. The CPU 65 performs various processes by executing programs or starting hardware. The ROM 66 stores various types of data. For example, the ROM 66 stores programs for the CPU 65 to execute and data necessary for the operation of the recording device 10. The RAM 67 is used as the work area for the CPU 65. The RAM 67 can also be used as a temporary data storage area.

[0052] The CPU 65 is connected to an ejection element driver 68 corresponding to each ejection element 33, an external pump driver 69, a circulation pump driver 70, a carriage motor driver 71, a transport motor driver 72, and a temperature detection element driver 73.

[0053] Each discharge element driver 68 is connected to a discharge element 33. An external pump driver 69 is connected to an external pump 18. A circulation pump driver 70 is connected to a circulation pump 46. A carriage motor driver 71 is connected to a carriage motor 74. The carriage motor 74 is a motor for moving the carriage 21. A transport motor driver 72 is connected to a transport motor 75. The transport motor 75 is a motor for rotating at least one of the transport rollers 13, 14, 15, and 16. A temperature detection element driver 73 is connected to a temperature detection element 76. The temperature detection element 76 is provided, for example, near the discharge port 39 of the discharge head 11. More specifically, the temperature detection element 76 is provided on the face surface 77 of the discharge head 11, as shown in Figure 3. The face surface 77 is the surface of the discharge unit 25 that constitutes the discharge head 11 that faces the recording medium 12.

[0054] The CPU 65 can receive recording data from the host device 78. The CPU 65 may also be able to receive recording data generated in the recording data generation unit provided in the recording device 10. The recording data is data for forming an image on the recording medium 12. Based on the recording data, the CPU 65 performs recording and transport processing. In the recording process, the CPU 65 causes the recording device 10 to perform recording operations by appropriately controlling at least each ejection element 33, the external pump 18, the circulation pump 46, and the carriage motor 74. In the transport process, the CPU 65 causes the recording device 10 to perform transport operations by appropriately controlling at least the transport motor 75. The recording and transport operations begin after the temperature T of the ejection head 11 reaches the target temperature Tth.

[0055] <<Adjusting the flow rate of the circulating ink>> Figure 7 is a graph showing the relationship between the setting of the rotational speed (pump rotations) of the circulation pump 46 and time. The rotational speed of the circulation pump 46 installed in the circulation path 500 is specified in order to adjust the flow rate of the ink circulating in the circulation path 500.

[0056] Specifically, a first rotational speed V1, a second rotational speed V2, and a third rotational speed V3 are specified. The first rotational speed V1 is the minimum value (rotational speed) of the circulation pump 46 required to circulate the ink in the circulation path 500 without solidifying it. The second rotational speed V2 is the rotational speed of the circulation pump 46 during the recording operation. The third rotational speed V3 is the rotational speed of the circulation pump 46 before the recording operation. This "before the recording operation" refers to the period from when the circulation pump 46 is started in response to the recording command until the recording operation begins. The second rotational speed V2 is greater than the third rotational speed V3, and the third rotational speed V3 is greater than the first rotational speed V1 (v1 <v3<v2)。

[0057] The first rotational speed V1, the second rotational speed V2, and the third rotational speed V3 are used by the CPU 65 that performs the recording process. The CPU 65 can adjust the flow rate of ink flowing through the circulation path 500 by controlling the circulation pump 46 (controlling the setting of the pump rotational speed).

[0058] <<Recording Process>> Figure 8 is a flowchart showing an example of a series of processes (recording processes) performed in the recording device 10. The series of processes shown in Figure 8 are realized by the CPU 65 reading a program stored in ROM 66 or the like into RAM 67 and executing it. Some or all of the functions of the steps in Figure 8 may be realized by hardware such as an ASIC or electronic circuit. The symbol "S" in the description of each process means that it is a step in the flowchart (the same applies to flowcharts in this specification hereafter). Figure 9 is a graph showing the relationship between the flow velocity of ink flowing through the circulation path 500 (ink circulation flow velocity) and time.

[0059] The following explanation will be given using Figures 8 and 9. The series of processes shown in Figure 8 begins when the CPU 65 receives a recording command. The recording command is supplied from the operation unit provided in the recording device 10 or from the host device 78. The recording command supplied from the operation unit is generated based on the user's operation to the operation unit.

[0060] In S801, the CPU 65 starts heating the ink. That is, the CPU 65 starts supplying power to each ejection element 33. As a result, each ejection element 33 generates heat and starts heating the ink circulating in the circulation path 500. Once the ink heating starts, the process proceeds to S802.

[0061] In S802, the CPU 65 sets a third rotational speed V3 as the pump rotational speed of the circulation pump 46 provided in each circulation path 500. As a result, as shown in Figure 9, the circulation pump 46 provided in each circulation path 500 starts to drive, and the flow velocity of the ink in each circulation path 500 gradually increases toward the flow velocity corresponding to the third rotational speed V3. Once the third rotational speed V3 is set, the process proceeds to S803.

[0062] In S803, the CPU 65 uses the temperature sensing element 76 to obtain the temperature T of the discharge head 11. Once the temperature T of the discharge head 11 is obtained, the process proceeds to S804.

[0063] In S804, the CPU 65 compares the temperature T of the ejection head 11, obtained in S803, with the target temperature Tth. If the temperature T of the ejection head 11 is less than or equal to the target temperature Tth, the process returns to S803. If the temperature T of the ejection head 11 exceeds the target temperature Tth, the process proceeds to S805.

[0064] In S805, the CPU 65 sets the second rotational speed V2 as the pump rotational speed of the circulation pump 46 provided in each circulation path 500. As a result, as shown in Figure 9, the flow velocity of the ink in each circulation path 500 increases further from the flow velocity corresponding to the third rotational speed V3. Once the second rotational speed V2 is set, the process proceeds to S806.

[0065] In S806, the CPU 65 causes the recording device 10 to start recording and transport operations. For example, the CPU 65 loads the recording data into the RAM 67. The CPU 65 also controls each ejection element 33, carriage motor 74, transport motor 75, etc., based on the recording data loaded into the RAM 67. As a result, the recording device 10 starts recording and transport operations and records (prints) the contents indicated in the recording data onto the recording medium 12.

[0066] As described above, this embodiment makes it possible to increase the heating efficiency of the ink. For example, in the recording device 10, the ejection element 33 starts heating before the recording operation to the recording medium 12 is performed. In addition, the CPU 65 controls the circulation pump 46 to slow down the flow rate of the liquid flowing through the circulation path 500 before the recording operation is performed compared to the flow rate of the liquid flowing through the circulation path 500 during the recording operation. As a result, cooling of each ejection element 33 that has started to heat up due to the flow of ink can be reduced in the state before the recording operation is performed. Therefore, the heating efficiency of the ink can be increased before recording to the recording medium 12. As a result, it is possible to shorten the time from the recording instruction to the start of recording.

[0067] Furthermore, the CPU 65 increases the flow velocity of the ink flowing through the circulation path (second rotation speed V2) before the recording operation is performed, compared to the lower limit flow velocity (first rotation speed V1) set according to the viscosity of the ink flowing through the circulation path 500. As a result, even if the flow velocity of the liquid flowing through the circulation path 500 is slowed down before the recording operation is performed, circulation in the circulation path 500 can continue without the ink solidifying.

[0068] <Second Embodiment> <<overview>> In the first embodiment, the case where the third rotational speed V3 set for the circulation pump 46 is fixed was described as an example. In this embodiment, the case where the third rotational speed V3 set for the circulation pump 46 is variable will be described as an example. In the following, explanations of content common to the first embodiment will be omitted as appropriate, and the differences will be mainly explained.

[0069] <<Recording Process>> Figure 10 is a flowchart showing an example of a series of processes (recording processes) performed in the second embodiment. In this embodiment, the process in S802 is replaced by the process in S1002.

[0070] In S1002, the CPU 65 sets the third rotational speed V3 of the circulation pump 46 provided in each circulation path 500 to an initial value. The initial value is the value corresponding to the temperature obtained using the temperature detection element 76 (the temperature immediately after heating starts in S801). Note that the initial value may be a value specified by the user, or it may be stored in advance in ROM 66 or the like.

[0071] Subsequently, the process proceeds to S803 and then to S804. In S804, if the temperature T of the discharge head 11 is less than or equal to the target temperature Tth, the process returns to S1002. In this case, the CPU 65 resets the value of the third rotational speed V3 of the circulation pump 46 provided in each circulation path 500 according to the temperature T of the discharge head 11 obtained in S803. Specifically, the CPU 65 decreases the value of the third rotational speed V3 as the temperature T of the discharge head 11 increases. That is, once heating starts in S801, the temperature T gradually increases. Therefore, the value of the third rotational speed V3 after resetting will be less than or equal to the value of the third rotational speed V3 before resetting.

[0072] In this way, when the temperature of the ejection head 11 is at the first temperature, the CPU 65 slows down the flow rate of the ink flowing through the circulation path 500 compared to when the temperature is at a second temperature lower than the first temperature. This makes it possible to further improve the heating efficiency of the ink before recording to the recording medium 12.

[0073] <Third Embodiment> <<overview>> In the first embodiment, the case in which a first rotational speed V1 is not set as the rotational speed of the circulation pump 46 provided in each circulation path 500 was described as an example. In this embodiment, the case in which a third rotational speed V3 is set after setting a first rotational speed V1 as the rotational speed of the circulation pump 46 provided in each circulation path 500 will be described as an example. In the following, explanations of content common to the first embodiment will be omitted as appropriate, and the differences will be explained mainly.

[0074] <<Recording Process>> Figure 11 is a flowchart showing an example of a series of processes (recording process) performed in the third embodiment. In this embodiment, the process S1101 is added to the recording process of the first embodiment. Specifically, the process S1101 is added between the processes S801 and S802. The process S1101 may also be added to the recording process of the second embodiment. In this case, the process S1101 is added between the processes S801 and S1002.

[0075] In S1101, the CPU 65 sets a first rotational speed V1 as the pump rotational speed of the circulation pumps 46 provided in each circulation path 500. After a predetermined period of time has elapsed since the first rotational speed V1 was set, the process proceeds to S802 (or S1002).

[0076] In this way, when the CPU 65 starts the circulation pump 46, it sets the minimum value (rotation speed) of the circulation pump 46 necessary to circulate the ink through the circulation path 500 without solidifying it. This further improves the heating efficiency of the ink before recording to the recording medium 12.

[0077] <About this disclosure> This disclosure is not limited to what has been described in the above embodiments (the first, second, and third embodiments).

[0078] In the above embodiment, the CPU 65 slowed the flow rate of ink through the circulation path 500 before the recording operation was performed compared to the flow rate of ink through the circulation path 500 during the recording operation. However, there are cases where heating (reheating) of the ink is required even when the recording operation is not performed. For example, there is an interval between recording operations. Therefore, the CPU 65 may also slow the flow rate of ink through the circulation path 500 during the recording operation interval compared to the flow rate of ink through the circulation path 500 during the recording operation. In this case, for example, when the CPU 65 receives a command to start an interval, it starts and executes the recording process shown in Figures 8 to 10. By adjusting the ink flow rate in this way, the heating efficiency of the ink can be increased even during the interval.

[0079] In the above embodiment, the CPU 65 did not differentiate the flow rate of the ink flowing through each circulation path 500 to which different types of ink are supplied. However, ink has the characteristic that its viscosity changes with temperature. Therefore, when different types of ink are supplied to each circulation path 500, the heating efficiency of the ink tends to differ for each circulation path 500. Thus, the CPU 65 may differentiate the flow rate of the ink for each circulation path 500 to which different types of ink are supplied. In this case, in S802, S1002, and S1101, the CPU 65 sets a different pump rotation speed for each circulation pump 46 in each circulation path 500. Specifically, the CPU 65 may set the pump rotation speed based on information (table) indicating the pump rotation speed of the circulation pump 46 associated with the type (viscosity) of ink. This information is stored in a storage device or ROM 66 provided in the host device 78.

[0080] For example, let's assume that the third rotation speed V3 associated with black ink is "AAr / s", and the third rotation speed V3 associated with cyan ink is "BBr / s". Also, let's assume that the third rotation speed V3 associated with magenta ink is "CCr / s", and the third rotation speed V3 associated with yellow ink is "DDr / s". Under these assumptions, for example, the setting of the third rotation speed V3 by the CPU 65 in the S802 would be as follows: The circulation pump 46 in the circulation path 500 to which black ink is supplied is set to "AAr / s". The circulation pump 46 in the circulation path 500 to which cyan ink is supplied is set to "BBr / s". The circulation pump 46 in the circulation path 500 to which magenta ink is supplied is set to "CCr / s". The circulation pump 46 in the circulation path 500 to which yellow ink is supplied is set to "DDr / s". By varying the ink flow rate every 500 circulation paths in this way, the heating efficiency can be further enhanced depending on the type of ink.

[0081] Furthermore, the type of ink supplied to one circulation path 500 may be changed. Therefore, the CPU 65 may change the flow rate of the ink flowing through the circulation path 500 according to the type of ink flowing through that circulation path 500. For example, the CPU 65 controls the circulation pump 46 so that the higher the viscosity of the ink, the greater the pump rotation speed. That is, the CPU 65 makes the rotation speed of the pump provided in the circulation path 500 through which ink of a first viscosity flows greater than the rotation speed of the pump provided in the circulation path 500 through which ink of a second viscosity, which is lower than the first viscosity, flows. In this case as well, the heating efficiency can be further increased according to the type of ink. The type of ink flowing through the circulation path 500 can be obtained as follows. For example, the CPU 65 can obtain the type of ink supplied to the circulation path 500 based on information input from the operation unit provided in the recording device 10 in response to user operation. Alternatively, the CPU 65 can obtain the type of ink supplied to the circulation path 500 based on information read from a barcode or the like provided in the ink tank 17.

[0082] In the above embodiment, the sizes of the discharge ports 39 were not different, but they may be different. Figure 12(a) is a cross-sectional view showing an example of a discharge unit 25 having relatively different discharge ports 39. Figure 12(b) is a view of the discharge unit 25 from above Figure 12(a). In the example shown in Figure 12, a first discharge port row 41 is located in one of the two pressure chambers 38. A second discharge port row 42 is located in the other of the two pressure chambers 38. The first discharge port row 41 is a row of discharge ports 39 spaced apart along the Y direction. The second discharge port row 42 is a row of discharge ports 39 spaced apart along the Y direction. The size of the first discharge port 391, which forms the first discharge port row 41, is larger than the size of the second discharge port 392, which forms the second discharge port row 42. For example, the first discharge port 391 is formed to a size capable of dispensing 5 pL of ink. The second nozzle 392 is formed to a size capable of ejecting 2 pL of ink. Specifically, the diameter of the first nozzle 391 is substantially 16.4 μm. The diameter of the second nozzle 392 is substantially 9.2 μm.

[0083] The circulation path corresponding to the first discharge port 391 and the circulation path corresponding to the second discharge port 392 are provided independently. The ink flowing through the circulation path corresponding to the first discharge port 391 and the ink flowing through the circulation path corresponding to the second discharge port 392 do not intersect with each other. The ink discharged from the first discharge port 391 and the ink discharged from the second discharge port 392 may be the same or different. When the circulation paths corresponding to the first discharge port 391 and the second discharge port 392 are provided independently, the CPU 65 may make the flow rate of the ink flowing through each circulation path different for each circulation path. In this case as well, the heating efficiency can be further increased depending on the type of ink.

[0084] In the above embodiment, the heating means for heating the ink flowing through the circulation path 500 was the ejection element 33. However, the heating means may be a temperature control element (temperature control heater) for adjusting the temperature of the ejection head 11. This temperature control element may be provided inside the ejection head 11 or outside the ejection head 11. Note that the heating means may include at least one of the ejection element 33 and the temperature control element.

[0085] In the above embodiment, the circulation means for circulating the ink in the circulation path 500 at a flow rate according to the setting was the circulation pump 46. The circulation pump 46 is a pump that can circulate the ink at a flow rate according to the setting of the rotation speed. The circulation means may be a control valve (solenoid valve). The control valve is a valve that can circulate the ink at a flow rate according to the setting of the opening degree. The opening degree is set by the CPU 65. The control valve is provided in the circulation path 500. When the circulation means is a control valve, the first rotation speed V1 is replaced by the first opening degree A1. Also, the second rotation speed V2 is replaced by the second opening degree A2. Also, the third rotation speed V3 is replaced by the third opening degree A3. The first opening degree A1 is the minimum value (minimum opening degree) of the control valve necessary to circulate the ink in the circulation path 500 without coagulating the ink. The second opening degree A2 is the opening degree of the control valve during the recording operation. The third opening degree A3 is the opening degree of the control valve before the recording operation. The second opening degree A2 is larger than the third opening degree A3, and the third opening degree A3 is larger than the first opening degree A1 (A1 < A3 < A2). When the circulation means is a control valve, the rotation speed of the circulation pump 46 may be constant or variable. Also, the circulation means may be both the circulation pump 46 provided in the circulation path 500 and the control valve. In this case, the CPU 65 can control at least one of the circulation pump 46 and the control valve to adjust the flow rate of the ink flowing through the circulation path 500.

[0086] In the above embodiment, the adjustment means for adjusting the flow rate of the ink flowing through the circulation path 500 by controlling the setting of the circulation means was the CPU 65 that executes a program. However, the adjustment means may be hardware such as an ASIC or an electronic circuit that realizes one or more functions.

[0087] In the above embodiment, the circulation path 500 was formed inside the ejection head 11, but the embodiment is not limited to this. For example, a circulation path that circulates ink between the inside of the ejection head 11 and the outside of the ejection head 11 may be formed.

[0088] This disclosure can also be implemented by supplying a program that implements one or more of the above embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be implemented by a circuit (e.g., an ASIC) that implements one or more of the functions.

[0089] This disclosure includes configurations represented by the following examples of recording devices and recording methods. <Structure 1> A dispensing head that dispenses liquid, A circulation path that guides liquid to a discharge port provided in the discharge head, and circulates the liquid so as to guide any liquid that was not discharged from the discharge port back to the discharge port, A heating means for heating the liquid flowing through the aforementioned circulation path, A circulation means is provided inside the discharge head and circulates the liquid in the circulation path at a flow rate according to the setting, The system includes an adjustment means that controls the setting of the circulation means to adjust the flow velocity of the liquid flowing through the circulation path, The heating means starts heating before the recording operation to the recording medium is performed. The recording device is characterized in that the adjustment means slows down the flow velocity of the liquid flowing through the circulation path before the recording operation is performed compared to the flow velocity of the liquid flowing through the circulation path while the recording operation is performed.

[0090] <Structure 2> The recording device according to configuration 1, wherein the adjusting means slows down the flow velocity of the liquid flowing through the circulation path when the temperature of the discharge head is at a first temperature compared to when the temperature is at a second temperature lower than the first temperature.

[0091] <Structure 3> The recording device according to configuration 1 or 2, wherein the adjusting means changes the flow velocity of the liquid flowing through the circulation path according to the type of liquid flowing through the circulation path.

[0092] <Structure 4> The discharge head is equipped with a first discharge port and a second discharge port of relatively different sizes. The circulation path is provided independently, corresponding to the first discharge port and the second discharge port, The recording device according to configuration 1 to 3, wherein the adjusting means causes the flow velocity of the liquid flowing through the circulation path to differ for each circulation path.

[0093] <Structure 5> The aforementioned dispensing head is capable of dispensing multiple types of liquids separately. The aforementioned circulation paths are provided independently for each of the multiple types of liquids. The recording device according to configuration 1 to 4, wherein the adjustment means causes the flow velocity of the liquid flowing through the circulation path to differ for each circulation path.

[0094] <Composition 6> The recording apparatus according to configuration 1 to 5, wherein the adjustment means slows down the flow velocity of the liquid flowing through the circulation path during the interval of the recording operation compared to the flow velocity of the liquid flowing through the circulation path while the recording operation is being performed.

[0095] <Composition 7> The liquid flowing through the aforementioned circulation path has the characteristic of its viscosity changing with temperature. The recording apparatus according to configuration 1 to 6, wherein the adjusting means increases the flow velocity of the liquid flowing through the circulation path before the recording operation is performed, compared to a lower limit flow velocity set according to the viscosity of the liquid flowing through the circulation path.

[0096] <Structure 8> The recording device according to configurations 1 to 7, wherein the circulation means is at least one of a pump and a control valve.

[0097] <Composition 9> The recording device according to configurations 1 to 8, wherein the recording operation is started after the temperature of the discharge head reaches the target temperature.

[0098] <Composition 10> A recording device according to configurations 1 to 9, comprising a temperature detection element for acquiring the temperature of the discharge head, wherein the temperature detection element is provided near the discharge port of the discharge head.

[0099] <Composition 11> The recording device according to configurations 1 to 10, wherein the heating means includes a discharge element that generates thermal energy as discharge energy for discharging liquid from the discharge port.

[0100] <Composition 12> The recording device according to configuration 11, wherein the discharge element is provided in a portion of the circulation path that communicates with the discharge port.

[0101] <Composition 13> The recording device according to configuration 11, wherein the heating means includes a temperature control element for adjusting the temperature of the discharge head.

[0102] <Composition 14> The aforementioned circulation path is formed inside the discharge head in the recording device according to configurations 1 to 13.

[0103] <Composition 15> A dispensing head that dispenses liquid, A circulation path that guides liquid to a discharge port provided in the discharge head, and circulates the liquid so as to guide any liquid that was not discharged from the discharge port back to the discharge port, A heating means for heating the liquid flowing through the aforementioned circulation path, A recording method for a recording device comprising a circulation means disposed inside the discharge head for circulating the liquid in the circulation path at a flow rate according to a setting, Before the recording operation to the recording medium is performed, the heating means is started to heat up. A recording method characterized by controlling the settings of the circulation means so that the flow velocity of the liquid flowing through the circulation path before the recording operation is performed is slower than the flow velocity of the liquid flowing through the circulation path while the recording operation is being performed.

Claims

1. A dispensing head that dispenses liquid, A circulation path that guides liquid to a discharge port provided in the discharge head, and circulates the liquid so as to guide any liquid that was not discharged from the discharge port back to the discharge port, A heating means for heating the liquid flowing through the aforementioned circulation path, A circulation means is provided inside the discharge head and circulates the liquid in the circulation path at a flow rate according to the setting, The system includes an adjustment means that controls the setting of the circulation means to adjust the flow velocity of the liquid flowing through the circulation path, The heating means starts heating before the recording operation to the recording medium is performed. The recording device is characterized in that the adjustment means slows down the flow velocity of the liquid flowing through the circulation path before the recording operation is performed compared to the flow velocity of the liquid flowing through the circulation path while the recording operation is performed.

2. The recording device according to claim 1, wherein the adjusting means slows down the flow velocity of the liquid flowing through the circulation path when the temperature of the discharge head is at a first temperature compared to when the temperature is at a second temperature lower than the first temperature.

3. The recording device according to claim 1, wherein the adjusting means changes the flow velocity of the liquid flowing through the circulation path according to the type of liquid flowing through the circulation path.

4. The discharge head is equipped with a first discharge port and a second discharge port of relatively different sizes. The circulation path is provided independently, corresponding to the first discharge port and the second discharge port, The recording device according to claim 1, wherein the adjusting means causes the flow velocity of the liquid flowing through the circulation path to differ for each of the circulation paths.

5. The aforementioned dispensing head is capable of dispensing multiple types of liquids separately. The aforementioned circulation paths are provided independently for each of the multiple types of liquids. The recording device according to claim 1, wherein the adjusting means causes the flow velocity of the liquid flowing through the circulation path to differ for each of the circulation paths.

6. The recording apparatus according to claim 1, wherein the adjustment means slows down the flow velocity of the liquid flowing through the circulation path during the interval of the recording operation compared to the flow velocity of the liquid flowing through the circulation path while the recording operation is being performed.

7. The liquid flowing through the aforementioned circulation path has the characteristic of its viscosity changing with temperature. The recording device according to claim 1, wherein the adjusting means increases the flow velocity of the liquid flowing through the circulation path before the recording operation is performed, compared to a lower limit flow velocity set according to the viscosity of the liquid flowing through the circulation path.

8. The recording device according to claim 1, wherein the circulation means is at least one of a pump and a control valve.

9. The recording device according to claim 1, wherein the recording operation is started after the temperature of the discharge head reaches a target temperature.

10. The recording device according to claim 1, further comprising a temperature detection element for obtaining the temperature of the discharge head, wherein the temperature detection element is provided near the discharge port of the discharge head.

11. The recording device according to claim 1, wherein the heating means includes a discharge element that generates thermal energy as discharge energy for discharging liquid from the discharge port.

12. The recording device according to claim 11, wherein the discharge element is provided in a portion of the circulation path that communicates with the discharge port.

13. The recording device according to claim 11, wherein the heating means includes a temperature control element for adjusting the temperature of the discharge head.

14. The recording device according to claim 1, wherein the circulation path is formed inside the discharge head.

15. A dispensing head that dispenses liquid, A circulation path that guides liquid to a discharge port provided in the discharge head, and circulates the liquid so as to guide any liquid that was not discharged from the discharge port back to the discharge port, A heating means for heating the liquid flowing through the aforementioned circulation path, A recording method for a recording device comprising a circulation means disposed inside the discharge head for circulating the liquid in the circulation path at a flow rate according to a setting, Before the recording operation to the recording medium is performed, the heating means is started to heat up. A recording method characterized by controlling the settings of the circulation means so that the flow velocity of the liquid flowing through the circulation path before the recording operation is performed is slower than the flow velocity of the liquid flowing through the circulation path while the recording operation is being performed.

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