Recording device and control method

Abstract

To reduce an ink discharge amount during ink filling.SOLUTION: A suction pump stops suction of a recording head after performing first suction on the recording head, and after that, performs second suction with a maximum driving speed higher than the driving speed at the end of the first suction.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a recording apparatus and a control method. [Background technology]

[0002] There is known an inkjet recording device that includes a recording head that includes an ejection port, a subtank, a liquid chamber flow path (hereinafter referred to as a liquid chamber) that connects the ejection port and the subtank, a filter provided between the subtank and the liquid chamber, and an ink tank that can store ink. In such a recording device, when the ink in the subtank runs out, it is necessary to replenish the subtank with ink from the ink tank and fill the liquid chamber with ink. When filling the liquid chamber with ink, air also flows in from the subtank at the same time as the ink, so air flows into the liquid chamber, and this air enters the ejection port during ejection, causing ejection defects.

[0003] Patent document 1 describes how, when refilling the recording head with ink, suction is applied to the liquid chamber to expel air from within the liquid chamber, and when ink enters the subtank and liquid chamber and high negative pressure is no longer applied to the filter, high suction with maximum negative pressure is applied. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US9925788 Summary of the Invention [Problem to be solved by the invention]

[0005] However, with the method of Patent Document 1, once bubbles accumulate, the bubbles are difficult to remove from that portion, and a large amount of ink must be consumed.

[0006] The present invention has been made in consideration of the above problems, and has an object to reduce the amount of ink discharged during ink refilling. [Means for solving the problem]

[0007] The present invention comprises a recording head having a tank for storing ink, a liquid chamber connected to the tank, a filter provided between the tank and the liquid chamber, and an ejection port for ejecting ink supplied from the liquid chamber, a cap covering the ejection port, and a suction pump for sucking ink from the recording head through the cap, wherein the suction pump performs a first suction on the recording head, then stops suctioning the recording head, and then performs a second suction whose maximum drive speed is faster than the drive speed at the end of the first suction. Effect of the Invention

[0008] According to the present invention, the amount of ink consumed during ink refilling can be reduced. [Brief description of the drawings]

[0009] [Figure 1] 1 is a perspective view of an inkjet recording apparatus according to a first embodiment. [Diagram 2] FIG. 3 is a detailed explanatory diagram showing a supply mechanism of the first embodiment. [Diagram 3] FIG. 2 is a perspective view of a recovery mechanism of the first embodiment. [Figure 4] FIG. 4 is a detailed explanatory diagram showing a recovery mechanism of the first embodiment. [Diagram 5] FIG. 2 is a schematic diagram illustrating a recording head according to the first embodiment. [Figure 6] FIG. 2 is a block diagram showing a control configuration of the first embodiment. [Figure 7] 5 is a flowchart showing a suction process according to the first embodiment. [Figure 8] 4 shows suction parameters for system cleaning in the first embodiment. [Figure 9] FIG. 4 is a schematic diagram of a negative pressure profile for system cleaning in the first embodiment. [Figure 10] FIG. 4 is a schematic diagram of the inside of the print head 4 during suction according to the first embodiment. [Figure 11]6 shows suction parameters for system cleaning of the second embodiment. [Figure 12] FIG. 13 is a schematic diagram of a negative pressure profile for system cleaning in the second embodiment. [Figure 13] 13 is a flowchart showing a suction process according to the third embodiment. [Figure 14] FIG. 13 is a schematic diagram of a negative pressure profile for system cleaning in the third embodiment. [Figure 15] 13 shows suction parameters for system cleaning in the fourth embodiment. [Figure 16] FIG. 13 is a schematic diagram of a negative pressure profile for system cleaning in the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (First embodiment) 1 is a perspective view showing an inkjet recording device (hereinafter also referred to as a recording device) used in this embodiment. A recording head 4 that ejects ink droplets is mounted on a carriage 3. The recording head 4 and a liquid container (main tank) 11 that stores ink are connected by a supply tube 8, which supplies ink to the recording head 4. The recording head 4 may be directly connected to the liquid container 11.

[0011] 2 is a detailed diagram showing the supply mechanism in this embodiment. The liquid container 11a for color ink is connected to the recording head 4a via a supply tube 8a. The liquid container 11b for black ink is connected to the recording head 4b via a supply tube 8b. The supply tubes 8a and 8b can be closed by manually moving the tube valve 9.

[0012] 3 is a perspective view of the recovery mechanism in this embodiment. A cap 20 for covering the ejection openings 7 of the recording head 4 is connected to a suction pump 23 via a suction tube 21.

[0013] FIG. 4 is a detailed diagram showing the details of the recovery mechanism in this embodiment. With the recording head 4 sealed with the cap 20, the suction pump 23 is driven to suck ink from the discharge port 7. The suction pump 23 rotates the shaft 25 on which the roller 24 is arranged in the direction of the arrow, so that the suction tube 21 is successively crushed at the portion held by the roller 24 and the guide 26, and the roller 24 rotates to generate a reduced pressure in the tube. As a result, the recording head 4 is depressurized through the cap 20, and ink is sucked from the discharge port 7. The amount of this suction is controlled by the number of rotations and the rotation speed of the roller 24, which are specified in advance. The ink discharged from the suction pump 23 is stored in the waste ink tank 28 via the waste ink tube 27. A waste ink absorber 29 is provided in the waste ink tank 28.

[0014] 5 is a schematic diagram showing the recording head 4 in this embodiment. The supply tube 8 is connected to the upper part of the recording head 4. A sub-tank 13 is provided inside the recording head 4. A porous absorbent may be provided inside the sub-tank 13. A liquid chamber 6 is provided below the sub-tank 13, a mesh filter 5 is provided between the sub-tank 13, and an ejection port 7 is provided below the liquid chamber 6.

[0015] Air bubbles form on the inner wall of the supply tube 8, and during printing, these bubbles gradually flow into the recording head 4. When air bubbles flow into the recording head 4, the amount of ink filled inside the subtank 13 gradually decreases, and the ink in the liquid chamber 6 runs out, resulting in poor ink ejection. In such a case, it is possible to recover by performing system cleaning at the user's instruction in order to refill the subtank 13 with ink.

[0016] The recording head 4 of this embodiment is an inkjet type recording head that uses thermal energy to eject ink, and is provided with a plurality of electrothermal transducers for generating thermal energy. More specifically, thermal energy is generated by a pulse signal applied to the electrothermal transducers, and film boiling is caused inside the ink liquid by this thermal energy, and furthermore, the bubbling pressure of the film boiling is used to eject ink from the ejection orifices to perform recording. Alternatively, a recording head that ejects ink using a piezoelectric element may be used.

[0017] FIG. 6 is a block diagram showing the configuration of the control. The ROM 4001 stores the control program to be executed and each set value in the control. The RAM 4002 expands the above-mentioned control program when it is executed, stores print data and control commands, and stores control variables in each control. The timer circuit 4003 is a circuit capable of acquiring the current time, or a circuit capable of measuring the elapsed time. The non-volatile memory 4004 is a storage means capable of storing parameters stored in the control even when the power of the main body is turned off, and writes and reads the time that is the starting point for calculating the elapsed time in the control of this embodiment. The control circuit 4000 executes the control program stored in the ROM 4001 or the control program expanded in the RAM 4002. The sequence of this embodiment is a part of the sequence executed by the above-mentioned control program.

[0018] The external connection circuit 4005 is a circuit that enables the control circuit 4000 to handle as an interface and control signal when the inkjet recording apparatus main body communicates with an external host device via wire or wirelessly. Data of an image to be printed is input from the outside via the external connection circuit 4005. The timer circuit 4003 may obtain the current time via the external connection circuit 4005.

[0019] The control circuit 4000 expands the received image data in the RAM 4002. Furthermore, based on the data on the RAM 4002, the control circuit 4000 controls the driving of the print head unit 4007 via the print head unit drive circuit 4006, and at the same time controls the carriage motor via the carriage motor drive circuit 4010. While moving the print head unit 4007 in the X direction under the control of the control circuit 4000, ink is ejected from the ejection openings of the print head unit 4007, and ink is ejected to a desired position on the print medium, thereby executing one print scan. Thereafter, the control circuit 4000 controls the paper feed motor 4013 via the paper feed motor drive circuit 4012 to transport the print medium by a desired distance. By repeating the print scan and the transport of the print medium, an image is printed on the print medium. The above is the print operation on the print medium.

[0020] In the suction recovery in the sequence of this embodiment, the control circuit 4000 controls the suction pump 23 via a purge motor drive circuit 4008 to suck a desired amount of ink from the print head. In addition, the control circuit 4000 controls the drive of the print head unit 4007 via a print head unit drive circuit 4006 to discharge a desired amount of ink into the cap. In this case, the pattern for driving the print head is based on data expanded in the RAM 4002, data in the ROM 4001, or data generated by the control circuit, as in the above-mentioned printing operation.

[0021] An inkjet recording device performs head recovery operations using suction recovery control for the purposes of removing air bubbles in the recording head, discharging stuck ink, and refilling with ink. Situations requiring a recovery operation include when the cap is left open after an abnormal termination, when an ink tank is replaced, when a certain amount of time has passed since the previous recovery operation was performed, and when the amount of ink droplets (number of dots) required for a recording operation since the previous recovery operation is equal to or exceeds a certain value. Under such circumstances, a recovery flag is set and stored in the non-volatile memory shown at 4004 in FIG. 6. Based on this recovery flag, a recovery operation (cleaning operation) is performed at a predetermined timing.

[0022] 7 is a flowchart showing the suction process after the start of the recovery operation in the first embodiment. This flowchart shows the process executed by the control circuit 4000 in accordance with the control program stored in the ROM 4001.

[0023] When the suction process is started, first, in step B01, the number of suction repetitions is set to K=1 in the RAM 4002, and the suction table is set to T=1. The suction table will be described in Fig. 8. Next, in step B02, the cap is closed by the carriage motor drive circuit 4010, and the cap 20 is pressed against the print head 4 to come into close contact with the discharge port surface.

[0024] In step B03, the pump starts rotating and suction starts by the purge motor drive circuit 4008. After a predetermined number of rotations, in step B04, the pump stops rotating by the purge motor drive circuit 4008, and suction ends.

[0025] In step B05, the cap is opened by the carriage motor drive circuit 4010, the cap is separated from the print head, and the inside of the print head is opened to atmospheric pressure. At this time, either the cap or the print head may move, or both may move. The method of opening to atmospheric pressure is not limited to cap opening, and may be, for example, a configuration in which the inside of the cap is opened to atmospheric pressure while the cap is covering the print head.

[0026] Next, in step B06, the pump is rotated again to suck and discharge the ink remaining in the cap. After a predetermined number of rotations, the pump rotation is stopped in step B07 and the sucking is stopped. After that, in step B08, the carriage motor drive circuit 4010 wipes the ejection surface.

[0027] If the number of suction repetitions K in the RAM 4002 is equal to the threshold value Kth in step B09, the suction is terminated and step B10 is performed. If the number of suction repetitions K is not equal to the threshold value Kth, the number of suction repetitions K and the suction table T are added in step B12, and the process returns to step B02 to repeat the suction. In this embodiment, Kth=2.

[0028] Next, after wiping the ejection surface in step B10, the recording head unit drive circuit 4006 executes preliminary ejection in step B11, and this process ends. Preliminary ejection is the ejection of ink that is not based on image data sent to the recording device by the user, and is performed to maintain and recover the ejection state. Preliminary ejection is performed by ejecting ink into the cap 20 or onto the platen that supports the recording medium.

[0029] In this embodiment, the release to atmospheric pressure is performed by separating the cap from the recording head, but it may also be performed by opening an atmospheric release valve provided on the cap.

[0030] FIG. 8 is a table showing suction parameters of system cleaning (B03-B04) in the first embodiment. In system cleaning, the driving amount of both suction tables 1 and 2 is set to 300000, and the driving speed is set to 500 for suction table 1 and 5000 for suction table 2. In this way, suction table 2 performs suction at a driving speed faster than suction table 1. At this time, the speed of suction table 1 is a speed that does not break the meniscus in the filter, and the speed of suction table 2 is faster than the flow speed generated by printing by ink ejection. In the first B03 (suction table T=1) of the flowchart in FIG. 7, suction based on suction table 1 (hereinafter also referred to as first suction) is performed. In the second B03 (suction table T=2), suction based on suction table 2 (hereinafter also referred to as second suction) is performed.

[0031] 9 is a schematic diagram of a negative pressure profile of system cleaning in the first embodiment of the present invention. The cap negative pressure of system cleaning has a two-peak negative pressure waveform. Since the drive speeds of the first suction and the second suction are different, the maximum achieved negative pressure is P1 in the first suction and P2 in the second suction. The maximum drive speed of the second suction (P2 here) is faster than the drive speed at the end of the first suction (P1 here).

[0032] 10(a) to (f) are schematic diagrams of the inside of the recording head 4 during suction.

[0033] FIG. 10(a) shows the state when B01 in FIG. 7 is set to K=1. The ink in the subtank 13 is not completely empty, and there is still residual ink 31 remaining. In FIG. 10(b), ink is supplied from the main tank 11 to the entrance of the subtank 13 by suction (B03, K=1, T=1). At this time, both ink and air pass through the filter due to the residual ink 31 at first, generating a large amount of bubbles. After that, as shown in FIG. 10(c), the ink supplied from the liquid container 11 and entering the subtank is sucked in at a speed that does not break the meniscus at the filter (B03, K=1, T=1), thereby preventing the generation of new bubbles. At this time, if the suction is not performed at a low speed, the meniscus of the filter 5 is broken as shown in FIG. 10(c`), and the air in the subtank 13 is also sucked in at the same time, generating a large amount of bubbles. FIG. 10(d) shows the state after time has passed since FIG. 10(c). If the drive speed is increased from this state without releasing the air to the atmosphere and suction is performed at K=2, T=2, the flow field created at stage (d) does not change significantly. Therefore, the bubbles in the area with a slow flow rate are not easily subjected to force and are difficult to remove, so the drive amount must be increased to perform suction. The drive amount is proportional to the suction amount, and an increase in the drive amount leads to an increase in the amount of waste ink.

[0034] FIG. 10(e) shows the behavior of bubbles when the air release (B04) is performed after FIG. 10(d), and the effect of this embodiment will be described here. The air release initializes the flow field, and bubbles gather near the filter 5. FIG. 10(f) shows the movement of bubbles during suction at K=2, T=2 when the drive speed is increased after that. At this time, since the flow field has been initialized once, a uniform force is applied during suction at K=2, T=2, making it easier for bubbles to escape. In addition, since the flow field at this time is similar to the discharge time when actually printing, even if bubbles remain here without being discharged, it is possible to prevent poor printing if the suction speed at K=2, T=2 is sufficient for the speed of the flow field during recording.

[0035] As described above, after performing the first suction, the flow field is initialized once and then the second suction is performed, thereby making it possible to efficiently expel bubbles and reducing the amount of ink consumed when filling the recording head with ink.

[0036] Second Embodiment In the first embodiment, suction is performed only at K=1, T=1 and at K=2, T=2, which has a faster drive speed than the K=1, T=1 suction, but the present invention is not limited to these two suctions. Here, the suction table speed T in the first embodiment is set to Tα. The following mainly describes the differences from the first embodiment.

[0037] If the supply flow path (supply tube 8 in this embodiment) connecting the liquid container 11 and the subtank is not filled with ink (the state shown in Figure 10(a)), even if the ink is moved from the liquid container 11 to the recording head by suction at a driving speed faster than the first suction, there is no ink near the filter 5, so no bubbles are generated in the filter 5.

[0038] This embodiment also performs the suction step shown in Fig. 7. Differences from the first embodiment will be described.

[0039] 11 is a table showing suction parameters for system cleaning (B03-B04) in the second embodiment. When ink is sucked from the liquid container 11 to the subtank 13 before filling the ink above the filter 5, suction is performed using the suction table 1 (third suction). At this time, suction can be performed at a speed Tβ faster than the suction of Tα=1 in the first embodiment. At this time, Tβ=1 may be either faster or slower than Tβ=3.

[0040] Figure 12 is a schematic diagram of the negative pressure profile when suction is performed with the suction parameters in Figure 11. In this way, by performing suction at a high speed when no bubbles are generated, the suction time can be reduced.

[0041] (Third embodiment) In the second embodiment, an air vent is sandwiched between suction table 1, which fills the supply flow path with ink, and suction table 2, which fills the filter 5 with ink, but it is not essential to include an air vent. The reason for sandwiching an air vent between suction table 2 and suction table 3 is to initialize the foam state, but the amount of foam generated between suction tables 1 and 2 is not large to begin with, and the subsequent suction table 2 is not intended to expel foam. The following mainly describes the differences from the above-mentioned embodiments.

[0042] Figure 13 is a flow chart showing the suction process when there is no release to the atmosphere between suction table 1 and suction table 2 in Figure 11. C01-C04 in Figure 13 perform the same processing as B01-04 in Figure 11, and C06-C13 in Figure 13 perform the same processing as B05-B12 in Figure 11. If the suction table is 1 (T=1) in C05, release to the atmosphere by opening the cap is skipped and the process proceeds to C10.

[0043] Fig. 14 is a schematic diagram of a negative pressure profile when suction is performed according to the flowchart of Fig. 13 with the suction parameters of Fig. 11. By not opening to the atmosphere, the suction time can be further reduced compared to the second embodiment, and since there is no suction while the negative pressure is increasing, this can also contribute to reducing waste ink.

[0044] (Fourth embodiment) In the first embodiment, the suction at the second driving speed is performed only once, but it may be performed multiple times. The following mainly describes the differences from the above-mentioned embodiments.

[0045] 15 is a table showing suction parameters for system cleaning in the fourth embodiment. Suction at the second drive speed is divided into three times. The number of times to divide the suction is arbitrary.

[0046] FIG. 16 is a schematic diagram of a negative pressure profile when suction is performed with the suction parameters of FIG.

[0047] The reason why the ink is released to the atmosphere before suction at the second drive speed is to initialize the state of any bubbles inside. Even if initialization is performed once, as suction continues, areas where the ink flow speed is slow and areas where bubbles are trapped will similarly appear inside the ink chamber 6. For this reason, by dividing the suction at the second drive speed and inserting an opening to the atmosphere between them, the initial state can be created multiple times, making it easier to remove bubbles.

[0048] Summary of the embodiment Some features illustrated in the embodiment can be summarized as follows.

[0049] (Configuration 1) a recording head including a tank for storing ink, a liquid chamber connected to the tank, a filter provided between the tank and the liquid chamber, and an ejection port for ejecting ink supplied from the liquid chamber; A cap for covering the discharge port; a suction pump that sucks ink from the recording head through the cap; having a suction pump that performs a first suction on the recording head, stops suction on the recording head, and then performs a second suction having a maximum drive speed faster than the drive speed at the end of the first suction.

[0050] (Configuration 2) 2. The recording apparatus according to claim 1, wherein the suction of the recording head is stopped by opening the ejection opening to the atmosphere.

[0051] (Configuration 3) 3. The recording device according to claim 1, wherein an absorbent is provided in the tank.

[0052] (Configuration 4) A liquid container for storing ink; a tube connecting the liquid container and the recording head, 4. The recording apparatus according to any one of configurations 1 to 3, wherein ink is supplied from the liquid container to the recording head via the tube.

[0053] (Configuration 5) 5. The recording apparatus according to any one of configurations 1 to 4, wherein the second suction is performed by sucking the recording head with the suction pump and stopping the suction a plurality of times.

[0054] (Configuration 6) 6. The recording apparatus according to any one of configurations 1 to 5, wherein a period of time during which the second suction is performed is shorter than a period of time during which the first suction is performed.

[0055] (Configuration 7) 7. The recording apparatus according to any one of configurations 1 to 6, wherein a third suction is performed before the first suction, the third suction having a maximum drive speed faster than the speed at the end of the first suction.

[0056] (Configuration 8) 8. The recording apparatus according to configuration 7, wherein suction of the recording head is stopped between the third suction and the first suction.

[0057] (Configuration 9) 9. The recording apparatus according to configuration 8, wherein the suction of the recording head is stopped by opening the ejection opening to the atmosphere.

[0058] (Configuration 10) 10. The recording apparatus according to any one of configurations 7 to 9, wherein a time period for the second suction is longer than a time period for the third suction.

[0059] (Configuration 11) 11. The recording apparatus according to any one of configurations 7 to 10, wherein a time period of the third suction is longer than a time period of the first suction.

[0060] (Configuration 12) 10. The recording apparatus according to configuration 2 or 9, wherein the opening to the atmosphere is achieved by separating the cap from the recording head.

[0061] (Configuration 13) A control method for a recording device having a tank for storing ink, a liquid chamber connected to the tank, a filter provided between the tank and the liquid chamber, a recording head having an ejection port for ejecting ink supplied from the liquid chamber, a cap for covering the ejection port, and a suction pump for sucking ink from the recording head through the cap, comprising: a control method for a recording device, the method comprising: causing the suction pump to perform a first suction on the recording head, stop suctioning the recording head, and then perform a second suction having a maximum drive speed faster than the drive speed at the end of the first suction. [Explanation of symbols]

[0062] 3 Carriage 4 Recording head 5. Filter inside the recording head 6 Ink chamber inside the recording head 7 Outlet 8 Supply Tube 11 Liquid containers 20 Cap 23 Suction Pump

Claims

1. a recording head including a tank for storing ink, a liquid chamber connected to the tank, a filter provided between the tank and the liquid chamber, and an ejection port for ejecting ink supplied from the liquid chamber; A cap for covering the discharge port; a suction pump that sucks ink from the recording head through the cap; having a suction pump that performs a first suction on the recording head, stops suction on the recording head, and then performs a second suction having a maximum drive speed faster than the drive speed at the end of the first suction.

2. 2. The recording apparatus according to claim 1, wherein the suction of the recording head is stopped by opening the ejection openings to the atmosphere.

3. 2. The recording apparatus according to claim 1, wherein an absorbent is provided inside the tank.

4. A liquid container for storing ink; a tube connecting the liquid container and the recording head, 2. The recording apparatus according to claim 1, wherein ink is supplied from said liquid container to said recording head through said tube.

5. 2. The recording apparatus according to claim 1, wherein the second suction is performed by performing a cycle of suctioning the recording head by the suction pump and stopping the suction a plurality of times.

6. 2. The recording apparatus according to claim 1, wherein a period of time during which the second suction is performed is shorter than a period of time during which the first suction is performed.

7. 2. The recording apparatus according to claim 1, further comprising: a third suction step, the third suction step being performed before the first suction step, the third suction step having a maximum drive speed faster than the speed at the end of the first suction step.

8. 8. The recording apparatus according to claim 7, wherein suction of the recording head is stopped between the third suction and the first suction.

9. 9. The recording apparatus according to claim 8, wherein the suction of the recording head is stopped by opening the ejection openings to the atmosphere.

10. 10. The recording apparatus according to claim 7, wherein a time period of the second suction is longer than a time period of the third suction.

11. 11. The recording apparatus according to claim 7, wherein a time period of the third suction is longer than a time period of the first suction.

12. 10. The recording apparatus according to claim 2, wherein the opening to the atmosphere is achieved by separating the cap from the recording head.

13. A control method for a recording device having a tank for storing ink, a liquid chamber connected to the tank, a filter provided between the tank and the liquid chamber, a recording head having an ejection port for ejecting ink supplied from the liquid chamber, a cap for covering the ejection port, and a suction pump for sucking ink from the recording head through the cap, comprising: a control method for a recording device, the method comprising: causing the suction pump to perform a first suction on the recording head, stop suctioning the recording head, and then perform a second suction having a maximum drive speed faster than the drive speed at the end of the first suction.

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