JP6441620B2 - Ink circulating device cleaning device and ink circulating device cleaning method - Google Patents

Description

  Embodiments described herein relate generally to an ink circulation device cleaning device and an ink circulation device cleaning method.

  In a printing apparatus, it is required to stably eject inks for various uses as well as printing inks that are generally used. For example, an ink that is cured by UV light or an ink in which metal particles are dispersed may be used as needed. In order to discharge them stably, an ink jet head having an ink circulation device has been developed.

  In order to perform various types of printing with one printing apparatus, there are cases where it is desired to change the type of ink attached to the printing apparatus. In such a case, an operation is performed in which the ink cartridge attached to the cartridge holder of the printing apparatus is removed and another ink cartridge is replaced with the cartridge holder. If one ink cartridge is removed from the printing device and another ink cartridge is installed immediately, the ink and the ink cartridge before the change remaining in the ink supply path, the circulation device, and the ink head are removed. The changed ink that is replenished is mixed. When different types of ink are mixed, problems such as color mixing and, in some cases, pigment aggregation, precipitation, and sedimentation, occur.

  Therefore, at the time of ink replacement, a cleaning sequence for cleaning the inside of the ink supply path of the printing apparatus is performed. In this cleaning sequence, the cleaning liquid cartridge in which the cleaning liquid is sealed is mounted on the cartridge holder. A cleaning liquid introducing step for introducing the cleaning liquid from the cleaning liquid cartridge into the ink supply path, and a cleaning liquid discharging step for sucking and discharging the introduced cleaning liquid to the capping means side in a state where the nozzle forming surface of the recording head is sealed. Executed.

  In the cleaning sequence of the conventional apparatus, the ink chamber in the cleaning liquid cartridge is shaken by reciprocating the carriage of the printing apparatus between the cleaning liquid introducing step and the cleaning liquid discharging step as means for enhancing the cleaning effect, thereby cleaning the cleaning liquid in the ink chamber. There is a case where an agitation step of agitating is performed.

JP 2002-192751 A

  In the prior art, since the liquid level of the cleaning liquid in the cleaning liquid cartridge cannot be made sufficiently high, it is difficult to remove and clean ink adhering to a high position on the inner wall of the cleaning liquid cartridge. Further, the above-described conventional technique in which the carriage of the printing apparatus is reciprocated to shake the ink chamber in the cleaning liquid cartridge cannot be applied to a printing apparatus in which the ink head is fixed.

According to the cleaning apparatus of the ink circulation device of the embodiment, the ink tank, the inkjet head, the circulation device, the liquid level detection unit, and the control unit are provided. The ink tank has an ink chamber for containing ink. The ink jet head ejects ink. The circulation device circulates ink between the ink tank and the inkjet head. The liquid level detection unit can detect a plurality of vertical liquid level positions inside the ink chamber of the ink tank. The liquid level detection unit detects at least a first liquid level position that is a normal ink use position and a second liquid level position that is set to a higher liquid level position than the first liquid level position. . The control unit discriminates between the normal printing mode and the cleaning mode. In the normal printing mode, the control unit controls the liquid level position of the ink in the ink chamber at the first liquid level position of the liquid level detection unit. circulating the cleaning fluid and controls the level position of the cleaning liquid in the ink chamber until the second ink surface position. The liquid level detection unit includes a float, a permanent magnet, and a plurality of liquid level sensors. The float rotates in the vertical direction around the rotation fulcrum following the change of the liquid level inside the ink chamber. The permanent magnet is attached to the side surface of the float at the end opposite to the rotation fulcrum of the float. The plurality of liquid level sensors are arranged side by side in the vertical direction along the movement direction of the float that rotates up and down around the rotation fulcrum at a position facing the permanent magnet outside the ink chamber. The electric signal is switched according to the magnetic dose of the permanent magnet.

FIG. 2 is a perspective view showing the appearance of the inkjet head and the ink circulation device of the first embodiment. FIG. 3 is a front view showing a section of an ink chamber of the ink circulation device according to the first embodiment. FIG. 3 is a perspective view showing a cross section of the liquid level float of the ink chamber of the ink circulation device of the first embodiment. FIG. 3 is a longitudinal sectional view showing a liquid level position of normal ink in an ink chamber of the ink circulation device according to the first embodiment. FIG. 3 is a longitudinal sectional view showing a liquid level position of ink during a normal emergency stop of an ink chamber of the ink circulation device according to the first embodiment. FIG. 3 is a longitudinal sectional view showing a liquid level position during cleaning with a cleaning liquid in an ink chamber of the ink circulation device according to the first embodiment. FIG. 4 is a longitudinal sectional view showing a liquid surface position at an emergency stop during cleaning with the cleaning liquid in the ink chamber of the ink circulation device of the first embodiment. 6 is a flowchart illustrating a sequence for switching between a normal mode and a cleaning mode of the ink circulation device according to the first embodiment. 6 is a flowchart illustrating an emergency stop sequence when the liquid level of the ink circulation device according to the first embodiment is abnormal. 5 is a flowchart illustrating a cleaning sequence of the ink circulation device according to the first embodiment. 1 is a block diagram of an ink circulation device according to a first embodiment. FIG. 6 is a longitudinal sectional view showing a modification of the liquid level float of the ink chamber of the ink circulation device of the first embodiment.

  1 to 11 show a first embodiment. FIG. 1 shows an ink jet recording unit 1 used in an ink jet recording apparatus which is a printing apparatus. The ink jet recording unit 1 includes an ink jet head 2 that is a liquid discharge unit and an ink discharge unit, and an ink circulation device 3 that is a circulation unit. The ink circulation device 3 is disposed above the inkjet head 2, and the ink circulation device 3 and the inkjet head 2 are integrated. The ink jet recording unit 1 ejects ink onto the recording medium S to form a desired image.

  The ink circulation device 3 of the ink jet recording unit 1 includes an ink chamber case 4 as shown in FIG. The ink chamber case 4 is assembled with a pressure adjusting mechanism 5 on the upper side, a control board 6 on the back side, and an ink supply port 7 on the side surface side. The ink circulation device 3 circulates and supplies ink to the inkjet head 2 and adjusts the pressure of an ink pressure chamber (not shown) of the inkjet head 2. The ink circulating device 3 adjusts the pressure of the ink pressure chamber to adjust the pressure of the meniscus of the nozzle. Further, the ink circulation device 3 circulates and supplies ink to the inkjet head 2 to absorb bubbles contained in the ink I or remove foreign matters.

  FIG. 2 is a front view showing a section of the ink chamber case 4 of the ink circulation device 3 in cross section. As shown in FIG. 2, the ink chamber case 4 includes two ink tanks each having an ink chamber that stores ink. An upstream ink chamber 8 is formed in one of the two ink tanks, and a downstream ink chamber 9 is formed in the other. The upstream ink chamber 8 supplies the ink I to the inkjet head 2. The downstream ink chamber 9 collects the ink I from the inkjet head 2. The upstream ink chamber 8 and the downstream ink chamber 9 may be separated from each other or may be adjacent to each other via a common wall (not shown). The ink chamber case 4 is sealed against the outside air.

  The upstream ink chamber 8 and the downstream ink chamber 9 hold the ink I downward via the first liquid surface α1 or the second liquid surface α2, respectively. The upstream ink chamber 8 and the downstream ink chamber 9 form a first air chamber β1 or a second air chamber β2 upward via the first liquid surface α1 or the second liquid surface α2, respectively.

  The upstream ink chamber 8 includes an ink discharge pipe 10. The ink I is connected to the ink inlet 11 of the inkjet head 2 through the ink flow path pipe connected to the ink discharge pipe 10, and the ink I is sent to the inkjet head 2. A temperature sensor 12 (see FIG. 11) for measuring the temperature of the ink is provided in the middle of the ink channel tube. Examples of the temperature sensor 12 include a thermocouple, a resistance temperature detector, a thermistor, and the like. The upstream ink chamber 8 includes an ink supply pump 13 for supplying new ink from an ink cartridge (not shown) via a tube connected to the ink supply port 7. The ink replenishment pump 13 is a liquid replenishment unit and constitutes an ink replenishment unit. The upstream ink chamber 8 includes a circulation pump outlet 15 that sucks ink from an ink circulation pump 14 mounted on the back side of the ink chamber case 4. On the upper surface of the upstream ink chamber 8, a connection port 16 connected to the pressure sensor PS (see FIG. 11) and a first communication hole 17 communicating with the pressure adjustment mechanism 5 are provided. Further, the ink jet recording apparatus has a cartridge holder (not shown) on which an ink cartridge is detachably mounted. At least one of the ink cartridge for normal printing and the cleaning liquid cartridge for cleaning is mounted on the cartridge holder.

  The downstream ink chamber 9 includes an ink inflow pipe 18. The ink inflow pipe 18 communicates with the ink discharge port 19 of the inkjet head 2 and allows the ink I discharged from the ink discharge port 19 of the inkjet head 2 to flow in. The downstream ink chamber 9 includes a circulation pump inlet 20 for discharging the ink I to the ink circulation pump 14. On the upper surface of the downstream ink chamber 9, a connection port 21 connected to the pressure sensor PS (see FIG. 11) and a second communication hole 22 communicating with the pressure adjusting mechanism 5 are provided.

  The pressure sensor PS is connected to a first pressure sensor PS1 (not shown) that communicates with the first air chamber β1 of the upstream ink chamber 8 and a second air chamber β2 that communicates with the second air chamber β2 of the downstream ink chamber 9. A pressure sensor PS2 (not shown) is provided. The first pressure sensor PS1 detects the pressure of the first air chamber β1 of the upstream ink chamber 8. The second pressure sensor PS2 detects the pressure in the second air chamber β2.

  The structure of the upstream ink chamber 8 or the downstream ink chamber 9 is not limited as long as ink can be circulated favorably with the inkjet head 2. For example, a heater 23 (see FIG. 11) for heating the ink and a cooling device (not shown) may be provided so as to keep the temperature of the ink within a predetermined range.

  The circulation portion of the ink circulation device 3 includes a circulation path that reaches the circulation pump outlet 15 of the upstream ink chamber 8 from the circulation pump inlet 20 of the downstream ink chamber 9 through the ink circulation pump 14 by the conveying force of the ink circulation pump 14. The circulation unit includes an ink circulation pump 14 and a filter (not shown) on the circulation path. The ink circulation pump 14 is provided across the adjacent upstream ink chamber 8 and downstream ink chamber 9. The ink circulation pump 14 circulates the ink I so as to return from the downstream ink chamber 9 to the downstream ink chamber 9 through the upstream ink chamber 8 and the inkjet head 2. The circulation unit sucks from the circulation pump inlet 20 and sends the ink I to the upstream ink chamber 8 through the circulation pump outlet 15.

  The pressure adjusting mechanism 5 of the ink circulation device 3 includes a first pressure adjusting unit 5 a that adjusts the pressure in the upstream ink chamber 8 and a second pressure adjusting unit 5 b that adjusts the pressure in the downstream ink chamber 9. The first pressure adjusting unit 5a includes a first pressure adjusting pump (not shown), and the second pressure adjusting unit 5b includes a second pressure adjusting pump (not shown). Each of the pressure adjusting pumps sends air to the upstream ink chamber 8 or the downstream ink chamber 9 to increase the pressure in the circulation path. The first or second pressure adjusting pump discharges the air in the first air chamber β1 in the upstream ink chamber 8 or the second air chamber β2 in the downstream ink chamber 9 to the outside, respectively, Reduce pressure.

  While the ink I is sent and circulated from the downstream ink chamber 9 to the upstream ink chamber 8 by the circulation portion, the bubbles in the ink I rise in the direction opposite to the gravity direction (upward) due to buoyancy. Bubbles rising due to buoyancy reach the air chambers β1 and β2 above the first liquid level α1 of the upstream ink chamber 8 or the second liquid level α2 of the downstream ink chamber 9 and are removed.

  The ink circulation device 3 includes a first liquid level detection unit 24 that can detect a plurality of vertical liquid level positions inside the upstream ink chamber 8, and a plurality of vertical liquid level positions inside the downstream ink chamber 9. And a second liquid level detection unit 25 capable of detecting. The first liquid level detection unit 24 and the second liquid level detection unit 25 have the same configuration. Here, the configuration of the first liquid level detection unit 24 will be described, and the same parts of the second liquid level detection unit 25 will be denoted by the same reference numerals and description thereof will be omitted.

  The first liquid level detection unit 24 is formed by a liquid level float 26 and a plurality of five Hall ICs 27 which are liquid level sensors in the present embodiment. FIG. 3 is a perspective view showing a cross section of the liquid level float 26. The liquid level float 26 has a liquid level float case 28 that is formed airtight so that air inside does not leak outside. An arm 29 protrudes from one end of the liquid level float case 28. A rotation fulcrum 30 is provided at the tip of the arm 29. A permanent magnet 31 is fixed to the end of the liquid surface float case 28 on the side opposite to the rotation fulcrum 30. The liquid level float 26 is rotatably held in the ink chamber case 4 at one position of the liquid level float rotation fulcrum 30. Thereby, the liquid level float 26 is rotatable around the liquid level float rotation fulcrum 30. The air inside the liquid surface float case 28 has a sufficiently large volume, and the liquid surface float 26 can be floated on the ink or the cleaning liquid by its buoyancy. When the liquid level height of the ink or the cleaning liquid in the upstream ink chamber 8 changes, the liquid level float 26 rotates about the liquid level float rotation fulcrum 30 to a position where the buoyancy and its own weight are balanced. Therefore, the position of the permanent magnet 31 in the liquid surface float 26 is a position corresponding to the liquid surface height of the ink or cleaning liquid in the upstream ink chamber 8.

  The five Hall ICs 27 are arranged outside the upstream ink chamber 8, and are arranged in parallel along the vertical direction with appropriate set intervals. Each Hall IC 27 switches an electric signal according to the magnetic dose of the permanent magnet 31. Each Hall IC 27 reverses its output when the permanent magnet 31 in the liquid surface float 26 approaches and the magnetic flux density exceeds a threshold value (for example, 1.8 millitesla).

  Here, when the permanent magnet 31 comes between the adjacent Hall ICs 27, the distance between the adjacent Hall ICs 27 is determined so that there is no blank section in which neither Hall IC 27 detects the permanent magnet 31. Therefore, when the permanent magnet 31 comes between adjacent Hall ICs 27, there is a section in which both Hall ICs 27 detect the permanent magnets 31. In this embodiment, there are five Hall ICs 27 in each of the upstream ink chamber 8 and the downstream ink chamber 9. Accordingly, there are five liquid level heights at which only one Hall IC 27 detects the permanent magnet 31, and there are four liquid level heights at which the two Hall ICs 27 detect the permanent magnet 31. That is, each of the upstream ink chamber 8 and the downstream ink chamber 9 can detect the liquid level height at nine locations. In the present embodiment, the five Hall ICs 27 in the upstream ink chamber 8 are arranged in order from the top in FIG. 2 in the first detection point 27a1, the second detection point 27a2, the third detection point 27a3, and the fourth detection point 27a4. And the fifth detection point 27a5 are shown separately. Similarly, the five Hall ICs 27 in the downstream ink chamber 9 are arranged in order from the top in FIG. 2, the first detection point 27b1, the second detection point 27b2, the third detection point 27b3, the fourth detection point 27b4, and the fifth detection point. 27b5 is distinguished and displayed.

  Further, each of the five Hall ICs 27 of the upstream ink chamber 8 and the downstream ink chamber 9 is connected to a control unit 32 which is a CPU of a microcomputer for controlling the operation of the ink jet recording apparatus as shown in FIG. The control unit 32 includes a drive circuit 33 for the ink supply pump 13, a drive circuit 34 for the ink circulation pump 14, a drive circuit 35 for the heater 23, and a drive circuit 37 for the pressure adjustment motor 36 of the pressure adjustment mechanism 5. Each is connected. Furthermore, a program memory 38, a data memory 39, and a RAM 40 are connected to the control unit 32, and a host computer 42 is connected via a communication interface 41.

  In addition, the control unit 32 detects the liquid level height at nine locations of the upstream ink chamber 8 and the downstream ink chamber 9 based on detection signals from the five Hall ICs 27 of the upstream ink chamber 8 and the downstream ink chamber 9 respectively. To do. A plurality of types of control are performed using the detected liquid level heights of the upstream ink chamber 8 and the downstream ink chamber 9. In the present embodiment, for example, a mode switching sequence, a normal ink sequence, a cleaning sequence, and an emergency stop control sequence are performed.

  In the mode switching sequence, as shown in the flowchart of FIG. 8, the normal printing mode and the cleaning mode are discriminated based on whether or not the state in which the cleaning liquid cartridge is mounted on the cartridge holder of the ink jet recording apparatus is detected (Act1). ). Here, when a state in which the ink cartridge for normal printing is mounted in the cartridge holder is detected (Act 1: No), it is determined as the normal printing mode. In this case, the process proceeds to Act2 and a normal ink sequence is performed.

  Further, when the state in which the cleaning liquid cartridge for cleaning is mounted on the cartridge holder is detected in Act 1 (Act 1: Yes), it is determined as the cleaning mode. In this case, the process proceeds to Act3 and a cleaning sequence is performed.

  In the normal ink sequence, the control unit 32 performs the following control. The ink flow of the inkjet recording unit 1 will be described with reference to FIG. The ink stored in the downstream ink chamber 9 is sucked into the circulation pump 14 through the circulation pump inlet 20 by the conveying force of the circulation pump 14. The ink sucked into the circulation pump 14 is discharged to the upstream ink chamber 8 through the circulation pump outlet 15 by the conveying force of the circulation pump 14.

  The ink in the upstream ink chamber 8 is transported into the ink jet head 2 in the direction of ink flow indicated by the arrow in FIG. 2 by the transport force of the circulation pump 14, and then ink jet in the direction of ink flow indicated by the arrow in FIG. It leaves the head 2 and is conveyed to the downstream ink chamber 9.

  Next, the ink pressure adjustment will be described with reference to FIG. The pressure sensor PS periodically determines the pressures of the first air chamber β1 above the first liquid level α1 of the upstream ink chamber 8 and the second air chamber β2 above the second liquid level α2 of the downstream ink chamber 9. Sampling. The control unit 32 calculates the ink pressure in the vicinity of the ink head nozzles by calculation using two pressure values obtained from the pressure sensor PS.

  The control unit 32 compares the calculated pressure in the vicinity of the ink head nozzles with a preset upper limit pressure value and lower limit pressure value. When the calculated pressure in the vicinity of the ink head nozzle is larger than a preset upper limit pressure value, the control unit 32 performs pressure increase control using the pressure adjustment mechanism 5. When the calculated pressure near the ink head nozzle is smaller than a preset lower limit pressure value, the control unit 32 performs pressure reduction control using the pressure adjusting mechanism 5. By setting the sampling period of the pressure sensor to a short time such as 10 ms and canceling out the ink pressure fluctuation at a high speed, the ink pressure is always kept appropriate and good ink ejection performance is obtained.

  Next, the ink level control in the normal ink sequence will be described with reference to FIGS. When the ink cartridge is mounted on the ink jet recording apparatus and normal printing is performed, the control unit 32 controls the liquid level so that the liquid level heights of the upstream ink chamber 8 and the downstream ink chamber 9 are at the positions shown in FIG. . At this time, the first liquid level α1 of the upstream ink chamber 8 is at a position corresponding to the third detection point 27a3, and the second liquid level α2 of the downstream ink chamber 9 is at a position corresponding to the third detection point 27b3. As controlled respectively. In the present embodiment, positions corresponding to the third detection point 27a3 of the upstream ink chamber 8 and the third detection point 27b3 of the downstream ink chamber 9 are set as normal liquid level positions.

  When the first liquid level α1 of the upstream ink chamber 8 and the second liquid level α2 of the downstream ink chamber 9 are too high, the pressure adjustment mechanism 5 sends air into each of the ink chambers 8 and 9, and ink is used instead. Drain and lower the liquid level. Ink discharging means uses a method of purging ink from the ink head nozzles by increasing the pressure in the ink chambers 8 and 9, and a method using spits for ejecting ink from the ink head nozzles using the operation during printing There is.

  When the first liquid level α1 of the upstream ink chamber 8 and the second liquid level α2 of the downstream ink chamber 9 are too low, the pressure adjusting mechanism 5 sucks the air in each of the ink chambers 8 and 9 and replaces the supply pump instead. 13 replenishes ink into the ink chambers 8 and 9 and raises the liquid level. This operation of increasing the liquid level height of the first liquid level α1 of the upstream ink chamber 8 and the second liquid level α2 of the downstream ink chamber 9 is also called a filling sequence, and is also used when changing the ink. Is called.

  Further, for example, the liquid level in the upstream ink chamber 8 and the downstream ink chamber 9 rapidly rises due to a rapid temperature change, and the first liquid level α1 in the upstream ink chamber 8 and the second liquid level in the downstream ink chamber 9 are increased. When the liquid level α2 comes to the emergency stop position shown in FIG. 5, the control unit 32 performs emergency stop control. At this time, the second detection point 27a2 of the upstream ink chamber 8 and the second detection point 27b2 of the downstream ink chamber 9 are set to the emergency stop positions, respectively. FIG. 9 shows a flowchart of the emergency stop control sequence at the time of liquid level abnormality in the normal ink sequence at this time.

  In the emergency stop control when the liquid level is abnormal, the control unit 32 determines whether the first liquid level α1 of the upstream ink chamber 8 and the second liquid level α2 of the downstream ink chamber 9 have reached the second detection points 27a2 and 27b2. It is discriminated whether or not it is an emergency stop liquid level based on No (Act 11). When it is detected that the first liquid level α1 of the upstream ink chamber 8 and the second liquid level α2 of the downstream ink chamber 9 have not reached the second detection points 27a2 and 27b2 (Act 11: No). Advances to Act 12, and the normal ink sequence is continued.

  Further, in Act 11, when the state where the first liquid level α1 of the upstream ink chamber 8 and the second liquid level α2 of the downstream ink chamber 9 reach the second detection points 27a2 and 27b2 is detected (Act11: Yes) ) Is determined as an emergency stop. In this case, the process proceeds to Act 13 and an emergency stop sequence is performed. In this emergency stop sequence, the circulation pump 14 and the replenishment pump 13 are immediately stopped so that ink does not flow into the pressure adjusting mechanism 5 or the pressure sensor PS. In order to stop the rise of the liquid level, the pressure adjusting mechanism 5 has a first air chamber β1 above the first liquid level α1 of the upstream ink chamber 8 and a second air chamber of the second liquid level α2 of the downstream ink chamber 9. β2 is shielded from the outside air to make the ink chambers 8 and 9 airtight. After the emergency stop is completed, the control unit 32 sends a message prompting the user to start the ink discharge control via the communication interface 41.

  Further, when the control unit 32 determines that the cleaning mode is set by the mode switching sequence of FIG. 8, the control unit 32 proceeds to Act 3 and performs the cleaning sequence. FIG. 10 is a flowchart showing a cleaning sequence.

  In the cleaning sequence, the control unit 32 first discharges the ink before the change (Act 21). As described above, the ink discharging means uses a method of purging ink from the ink head nozzles by increasing the pressure in the ink chambers 8 and 9, and a spit that discharges ink from the ink head nozzles using the operation during printing. There is a method of using.

  Next, using the filling sequence described above, the replenishing pump 13 is driven to fill the cleaning liquid in the cleaning liquid cartridge to the normal liquid level in FIG. 4 (Act 22). At this time, when the cleaning liquid passes through the ink supply path, the ink before the change remaining in the ink supply path and the cleaning liquid are mixed.

  Next, when the cleaning liquid is filled up to the normal liquid level in FIG. 4, the replenishment pump 13 is stopped and the circulation pump 14 is driven to start circulation of the cleaning liquid (Act 23). At this time, the ink before cleaning and the cleaning liquid remaining in the circulation device 3 and the ink head are mixed by the circulation of the cleaning liquid. Thereafter, the process proceeds to Act 24, and the printing apparatus starts discharging the mixed liquid of the ink and the cleaning liquid from all the nozzles. After 5 minutes, the circulation pump 14 is stopped and the circulation is finished (Act 25). Subsequently, the mixed liquid of ink and cleaning liquid is discharged (Act 26). At this time, the number of repetitions (N) is counted as 1 (N = 1) (Act 27).

  Next, the replenishment pump 13 is driven to fill the cleaning liquid in the cleaning liquid cartridge to a liquid level position slightly higher ("N" mm higher) than the previous time (N = 1) (Act 28). At this time, in order to create a liquid level position that is slightly higher (“N” mm higher) than the previous time (N = 1), the control unit 32 sets a little time from the detection of the permanent magnet 31 to the stop of the filling sequence. Lengthen. When the cleaning liquid is filled up to a position slightly higher than the normal liquid level position in FIG. 4, the replenishment pump 13 is stopped. When the cleaning liquid passes through the ink supply path, the ink before the change remaining in the ink supply path and the cleaning liquid are mixed. Subsequently, the replenishment pump 13 is driven and the second cleaning liquid circulation operation is performed (Act 29). By the second circulation of the cleaning liquid, the ink before the change and the cleaning liquid remaining in the circulation device 3 and the ink head are mixed.

  Thereafter, the process proceeds to Act 30, and the printing apparatus starts discharging the mixed liquid of the ink and the cleaning liquid from all the nozzles. After 5 minutes, the circulation pump 14 is stopped and the circulation is finished (Act 31). Subsequently, the mixed liquid of ink and cleaning liquid is discharged (Act 32). At this time, the number of repetitions (N) is counted as N + 1 times (N = N + 1 = 2) (Act 33).

  Next, the process proceeds to Act 34, where it is determined whether or not the number of repetitions (N) is a predetermined number of preset times, for example, seven. If it is determined that the number of repetitions (N) is not seven (Act 34: No), the process returns to Act 28, and the replenishing pump 13 is driven to bring the cleaning liquid in the cleaning liquid cartridge to a slightly higher liquid level than the previous time. Fill and repeat Act 29-33. By repeating this, the liquid level of the cleaning liquid gradually increases, and the normal liquid level position of the inner walls of the ink chambers 8 and 9 (the third detection point 27a3 of the upstream ink chamber 8 and the third detection point 27b3 of the downstream ink chamber 9). The ink before the change attached to a higher position is washed away.

  In Act 34, when the number of repetitions (N) is determined to be 7 (Act 34: Yes), the cleaning sequence ends. For example, as shown in FIG. 6, the liquid level of the cleaning liquid at the end of the cleaning sequence is an intermediate position between the first detection point 27 a 1 and the second detection point 27 a 2 of the upstream ink chamber 8 and the first detection point of the downstream ink chamber 9. 27b1 and the second detection point 27b2 are set at positions corresponding to the intermediate positions. The liquid level position of the cleaning liquid at the end of the cleaning sequence is set to a second liquid level position higher than the first liquid level position, which is a normal ink use position.

  Note that, during the cleaning sequence, the liquid level is intentionally controlled to be higher than in the normal sequence, so the liquid level for determining an emergency stop is also set to a position higher than normal. For example, as shown in FIG. 7, the first detection point 27 a 1 of the upstream ink chamber 8 and the first detection point 27 b 1 of the downstream ink chamber 9 are set to positions corresponding to each other.

  In the ink circulation device 3 of the present embodiment, the first liquid level detection unit 24 and the second liquid level detection that can detect a plurality of liquid level positions in the vertical direction inside the upstream ink chamber 8 and the downstream ink chamber 9. Part 25. Then, the control unit 32 determines the normal printing mode and the cleaning mode. In the normal printing mode, the liquid level position of the ink in the ink chambers 8 and 9 is controlled by the first liquid level position that is the normal ink use position of the liquid level detection units 24 and 25. Further, in the cleaning mode, the liquid level position of the cleaning liquid in the ink chambers 8 and 9 is controlled at the second liquid level position set higher than the first liquid level position. Accordingly, the cleaning liquid can be filled up to a position higher than the ink adhering to the highest level of the inner walls of the ink chambers 8 and 9 of the circulation device 3 in the normal printing mode. For this reason, in the normal printing mode, it is possible to surely clean the portion higher than the ink adhering to the highest level of the inner walls of the ink chambers 8 and 9 of the circulation device 3, so that ink replacement with no ink remaining is possible.

  Therefore, when changing the type of ink to be installed in the printing apparatus, the ink before the change remaining in the ink supply path, the circulation device, and the ink head and the changed ink supplied from the ink cartridge are mixed. Can be surely prevented. Further, even in a printing apparatus that does not have a means for shaking the ink chamber by the head fixing method, it is possible to perform reliable ink replacement without ink remaining.

  FIG. 12 is a longitudinal sectional view showing a modified example of the liquid level float of the ink chambers 8 and 9 of the ink circulation device 3 of the first embodiment. In FIG. 12, the same parts as those in FIGS. 1 to 11 are denoted by the same reference numerals, and the description thereof is omitted. In this modification, a float storage chamber 51 that communicates with the upstream ink chamber 8 and the downstream ink chamber 9 is formed. A capsule-like float 52 is inserted into these float storage chambers 51 so as to be movable in the vertical direction. A permanent magnet 53 is fixed to the float 52.

  On the outer surfaces of the upstream ink chamber 8 and the downstream ink chamber 9, five Hall ICs 27 for detecting the magnetism of the permanent magnet 53 are provided at appropriate intervals along the vertical direction as in the first embodiment. Side by side.

  In this modification, the float 52 moves in the vertical direction in the float storage chamber 51 using the floating buoyancy in accordance with the change in the liquid level position of the ink or the cleaning liquid in the upstream ink chamber 8 and the downstream ink chamber 9. At this time, by detecting the position of the permanent magnet 53 of the float 52 with the five Hall ICs 27a1 to 27a5 and 27b1 to 27b5, the upstream ink chamber 8 and the downstream ink chamber 9 have the respective liquid level heights at nine locations. It can be detected.

  The liquid level detection unit may be of an optical type, for example, and may be configured to measure the ink amount by detecting the liquid level of the ink.

  According to these embodiments, since it is possible to clean up to a place higher than the ink adhering to the highest wall of the ink chamber inner wall of the circulation device, it is possible to clean the ink with little ink remaining, and there is no means for shaking the ink chamber. Even in the apparatus, it is possible to provide a cleaning device for an ink circulation device and a cleaning method for the ink circulation device that can clean ink with little ink remaining.

Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.
Hereinafter, the invention described in the scope of claims of the present application will be appended.
[1] An ink tank having an ink chamber for containing ink, an ink jet head for ejecting ink, a circulation device for circulating ink between the ink tank and the ink jet head, and an ink chamber of the ink tank A plurality of liquid surface positions in the vertical direction can be detected inside, and at least a first liquid surface position which is a normal ink use position and a second liquid surface position which is set higher than the first liquid surface position. A liquid level detection unit that detects a liquid level position of the liquid, and a normal printing mode and a cleaning mode, and in the normal printing mode, the ink in the ink chamber at the first liquid level position of the liquid level detection unit And a controller for controlling the liquid level position in the ink chamber at the second liquid level position in the cleaning mode.
[2] The control unit according to [1], wherein in the cleaning mode, the liquid level position is gradually increased from the first liquid level position to the second liquid level position. A cleaning device for the ink circulation device as described.
[3] The liquid level detector is configured to float vertically following a change in the liquid level inside the ink chamber, a permanent magnet attached to the float, and vertically outside the ink chamber. A plurality of Hall ICs arranged in parallel along the direction, each of which switches an electric signal in accordance with the magnetic dose of the permanent magnet, and the control unit changes the Hall as the float moves in the vertical direction. The cleaning device for an ink circulation device according to [1], further comprising means for detecting a liquid surface position inside the ink chamber based on an output signal from an IC.
[4] The controller sets for emergency stop where the liquid level in the ink chamber is higher than the first liquid level based on the detection result from the liquid level detector in the normal printing mode. An emergency stop control means for normal printing that shuts off the air above the liquid level in the ink chamber from the outside air when the state of rising to the position is detected and makes the ink chamber airtight, and the liquid level detection in the cleaning mode The liquid level in the ink chamber is detected when a state in which the liquid level in the ink chamber has risen to a set position for emergency stop that is higher than the second liquid level position is detected based on the detection result from the section. The cleaning device for an ink circulation device according to [1], further comprising an emergency stop control unit in a cleaning mode for blocking the upper air from outside air to make the ink chamber airtight.
[5] An ink circulation device cleaning method using the ink circulation device cleaning device according to any one of [1] to [4], wherein the normal printing mode and the cleaning mode are distinguished, and the normal printing is performed. In the mode, the liquid level position of the ink in the ink chamber is held at the first liquid level position of the liquid level detection unit, and in the cleaning mode, the liquid level position in the ink chamber at the second liquid level position. A method for cleaning an ink circulation device, characterized in that control for holding the ink is performed.

    DESCRIPTION OF SYMBOLS 1 ... Inkjet recording part, 2 ... Inkjet head, 3 ... Ink circulation device, 4 ... Ink chamber case, 5 ... Pressure adjustment mechanism, 7 ... Ink supply port, PS ... Pressure sensor, 8 ... Upstream ink chamber, 9 ... Downstream ink Chamber, 13 ... circulation pump, 14 ... replenishment pump, 24 ... first liquid level detection unit, 25 ... second liquid level detection unit, 26 ... liquid level float, 27 ... Hall IC, 31 ... permanent magnet, 32 ... Control unit.

Claims (5)

An ink tank having an ink chamber for containing ink;
An inkjet head that ejects ink;
A circulation device for circulating ink between the ink tank and the inkjet head;
A plurality of liquid surface positions in the vertical direction can be detected inside the ink chamber of the ink tank, and at least a first liquid surface position that is a normal ink use position and a liquid surface that is higher than the first liquid surface position A liquid level detection unit for detecting the second liquid level position set at the position;
In the normal printing mode, the liquid level position of the ink in the ink chamber is controlled by the first liquid level position of the liquid level detection unit, and in the cleaning mode, the normal printing mode and the cleaning mode are distinguished. and a control unit for circulating the washing liquid to control the liquid level position of the cleaning liquid in the ink chamber until the second ink surface position,
The liquid level detection unit follows a change in the liquid level inside the ink chamber, and floats to rotate up and down around a rotation fulcrum.
A permanent magnet attached to a side surface of the float at an end opposite to the rotation fulcrum of the float;
A plurality of lines are arranged in the vertical direction along the direction of movement of the float that moves up and down around the rotation fulcrum at a position facing the permanent magnet outside the ink chamber. A cleaning device for an ink circulation device, comprising: a plurality of liquid level sensors that switch an electric signal according to an amount. Wherein the control unit, the in cleaning mode, the ink circulation system according to 請 Motomeko 1 that controls the state gradually increasing the liquid level position from the first ink surface position to the second ink surface position Cleaning device. The liquid level sensor is a Hall IC,
Wherein, ink circulation according to 請 Motomeko 1 that have a means for detecting the liquid level inside the ink chamber by an output signal from the Hall IC which is changed with the vertical movement of the float Equipment cleaning equipment. The controller raises the liquid level position inside the ink chamber to an emergency stop set position higher than the first liquid level position based on the detection result from the liquid level detection unit in the normal printing mode. An emergency stop control means during normal printing for blocking the air above the liquid level in the ink chamber from the outside air when the detected state is detected, and making the ink chamber airtight;
When the liquid level position inside the ink chamber is detected to be higher than the second liquid level position to the emergency stop setting position based on the detection result from the liquid level detection unit in the cleaning mode. cleaning device of the ink circulation system according to 請 Motomeko 1 ink chamber by blocking air above the liquid surface of the ink chamber from the outside air that have a emergency stop control means at the time of cleaning mode airtightly. An ink circulation device cleaning method using the ink circulation device cleaning device according to any one of claims 1 to 4,
In the normal printing mode, the liquid level position of the ink in the ink chamber is held at the first liquid level position of the liquid level detection unit, and in the cleaning mode, the normal printing mode and the cleaning mode are distinguished. method for cleaning a line Ui ink circulating device control to maintain the liquid level position of the ink chamber at the second ink surface position.

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