JP7413819B2 - liquid discharge device - Google Patents

Description

The present invention relates to a liquid ejection device.

Patent Document 1 discloses an inkjet recording apparatus that includes a flushing amount counter that cumulatively counts the number of ink droplets ejected in a first flushing mode or a second flushing mode. In the recording apparatus, when the count value by the counter reaches a predetermined value, an empty suction operation is performed to suck the inner bottom of the capping means while the capping means and the nozzle forming surface of the recording head are separated from each other. be done.

In the idle suction operation, a portion of the ink is suctioned and discharged from the ink absorbing material disposed within the capping means. Further, the recording device is configured such that the count value in the counter is reset when the idle suction operation is executed.

Japanese Patent Application Publication No. 2007-125900

However, in the inkjet recording apparatus disclosed in Patent Document 1, the amount of ink inside the capping means is the sum of estimated values using counts by a counter. The actual amount of ink discharged into the capping means by flushing, purging, etc. varies due to changes in the viscosity of the ink due to temperature and other factors. In order to suction and discharge the discharged ink inside the capping means without leaving any residue, it is necessary to take this variation into consideration and set the suction and discharge time to be long, but this time is wasted.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a liquid ejecting device that does not waste the drive time of the suction section.

In order to solve the above problems, a liquid ejection device according to one aspect of the present invention includes a head unit having at least one nozzle for ejecting liquid, and a device for sealing the nozzle of the head unit. a cap portion having a lip; a cap displacement portion displacing the cap portion so as to bring the lip of the cap portion into contact with and away from the head unit; an electrode on which the ejected liquid can land, a detection section that is electrically connected to the electrode and detects that the liquid has been ejected from the nozzle toward the electrode, and discharges the liquid inside the cap section. a suction section for storing liquid discharged from the inside of the cap section by the suction section; a waste liquid storage section for storing the liquid discharged from the inside of the cap section by the suction section; and a waste liquid storage section for discharging the liquid remaining inside the cap section by driving the cap displacement section and the suction section. a control unit that causes a part of the lip to come into contact with the head unit and another part of the lip to move the cap part by driving the cap displacement part; With a portion of the cap section positioned in a predetermined posture separated from the head unit, and with the cap section positioned in the predetermined posture, the suction section is driven so as to discharge the liquid inside the cap section, and the suction section is driven so as to discharge the liquid inside the cap section. an electrical change caused by the detection unit changing from a state in which liquid exists between the head unit and the electrode to a state in which the liquid does not exist between the time when the unit starts driving and the reference time elapses; If detected, the drive of the suction unit is stopped before the reference time is reached, and the detection unit changes the state where the liquid exists between the head unit and the electrode to the state where the liquid does not exist. If no electrical changes caused by this are detected, the suction section is driven to the reference time.

According to one aspect of the present invention, it is possible to provide a liquid ejection device in which the drive time of the suction section is not wasted.

1 is a schematic diagram showing the configuration of a liquid ejection device according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing a connection relationship near a cap portion included in the liquid ejection device shown in FIG. 1. FIG. 2 is a block diagram showing the electrical configuration of the liquid ejection device shown in FIG. 1. FIG. 2 is a diagram showing suction purge and tilt contact operations performed by the liquid ejection device shown in FIG. 1. FIG. 2 is a graph showing voltages of electrodes included in the liquid ejection device shown in FIG. 1. FIG. 2 is a flowchart showing processing of the liquid ejection device shown in FIG. 1. FIG. 7 is a flowchart showing a process related to executing an idle suction operation for black ink among the processes shown in FIG. 6. FIG. 8 is a flowchart showing a continuation of the process shown in FIG. 7.

<Configuration of liquid ejection device 1>
FIG. 1 is a schematic diagram showing the configuration of a liquid ejection device 1 according to an embodiment of the present invention. As shown in FIG. 1, the liquid ejection device 1 includes a carriage 2, a sub-tank 3, an inkjet head 4, a platen 5, transport rollers 6 and 7, a maintenance unit 8, guide rails 9 and 10, and a cartridge. It includes a holder 11 and an ink cartridge 12.

Here, the direction from the carriage 2 to a waste liquid storage section 63 (described later) is defined as the X direction, the direction from the conveyance roller 6 to the conveyance roller 7 is defined as the Y direction, and the direction from the platen 5 to the carriage 2 is defined as the Z direction. Further, the Z direction is defined as an upward direction, and the direction opposite to the Z direction is defined as a downward direction. The Y direction is the conveyance direction of the paper P.

The carriage 2 is supported by two guide rails 9 and 10 extending in the scanning direction. The scanning direction is the X direction. Further, the scanning direction is a direction perpendicular to the conveyance direction of the paper P and parallel to a nozzle surface 4B, which will be described later. The carriage 2 is connected to a carriage motor 31, which will be described later, via a belt (not shown) or the like. When the carriage motor 31 is driven by a control device 23, which will be described later, the carriage 2 moves in the scanning direction along guide rails 9 and 10. Thereby, the inkjet head 4 moves between a maintenance position where it faces the cap part 61 and a non-maintenance position where it does not face the cap part 61.

The sub tank 3 is mounted on the carriage 2. Here, the liquid ejection device 1 is provided with a cartridge holder 11, and four ink cartridges 12 are removably attached to the cartridge holder 11. The four ink cartridges 12 each store black, yellow, cyan, and magenta inks as examples of liquid. The sub tank 3 is connected to four ink cartridges 12 via four tubes 13. As a result, four colors of ink are supplied from the four ink cartridges 12 to the sub-tank 3.

The inkjet head 4 is mounted on the carriage 2. The inkjet head 4 is an example of a head unit. The inkjet head 4 is supplied with four colors of ink from the sub-tank 3. The inkjet head 4 has a plurality of nozzles 4A that eject ink. The nozzle 4A is formed on a nozzle surface 4B, which is the lower surface of the inkjet head 4. Note that the scope of application of the present invention is not limited to the liquid ejection device 1 that includes the inkjet head 4 that has a plurality of nozzles 4A, but also applies to a liquid ejection device that includes an inkjet head that has one nozzle. It is. Further, the number of colors of ink ejected by the inkjet head 4 may be greater than four colors.

The platen 5 is arranged below the inkjet head 4 and faces the nozzle 4A and the nozzle surface 4B. The platen 5 extends over the entire length of the paper P in the scanning direction and supports the paper P from below. The conveyance roller 6 is arranged upstream of the inkjet head 4 and platen 5 in the conveyance direction. The conveyance roller 7 is arranged downstream of the inkjet head 4 and the platen 5 in the conveyance direction. The conveyance rollers 6 and 7 are connected to a conveyance motor 32, which will be described later, via gears (not shown) or the like. When the transport motor 32 is driven by the control device 23, the transport rollers 6 and 7 rotate, and the paper P is transported in the transport direction.

<Configuration of maintenance unit 8>
The maintenance unit 8 performs maintenance to restore the discharge state of the nozzle 4A. The maintenance unit 8 includes a cap portion 61, a suction portion 62, a waste liquid storage portion 63, a first electrode E1, and a second electrode E2. The cap portion 61 is disposed offset from the platen 5 in the scanning direction. When the carriage 2 is placed at the maintenance position by moving in the scanning direction relative to the platen 5, the nozzle 4A and the nozzle surface 4B face the cap portion 61.

FIG. 2 is a schematic diagram showing the connection relationship in the vicinity of the cap portion 61 included in the liquid ejection device 1 shown in FIG. As shown in FIG. 2, the inkjet head 4 has at least two nozzles: a first nozzle 41N and a second nozzle 42N. That is, the inkjet head 4 has at least one first nozzle 41N and at least one second nozzle 42N.

The first nozzle 41N discharges yellow, cyan, and magenta inks as color inks. The second nozzle 42N discharges black ink. That is, the nozzle 4A is divided into a first nozzle 41N and a second nozzle 42N. Note that the scope of application of the present invention is not limited to the liquid ejection device 1 that ejects color ink and black ink, but is also applicable to a liquid ejection device that ejects one color of ink.

The cap portion 61 includes a first cap portion 61A and a second cap portion 61B. The cap portion 61 is disposed at a position facing the inkjet head 4 and is for sealing the nozzle 4A by covering the nozzle 4A of the inkjet head 4.

The first cap portion 61A is for sealing the first nozzle 41N of the inkjet head 4 by covering it, and has a first lip 61D. The first lip 61D projects upward from the bottom 61C of the cap portion 61 and surrounds the first electrode E1.

The second cap part 61B shares a part of the first lip 61D of the first cap part 61A and is adjacent to the second cap part 61B. It has a second lip 61E. The first lip 61D and the second lip 61E share the boundary between the first cap part 61A and the second cap part 61B. The second lip 61E projects upward from the bottom 61C of the cap portion 61 and surrounds the second electrode E2.

The cap portion 61 is connected to a cap displacement portion 33, which will be described later. The cap displacement section 33 includes a motor, a gear connected to the motor, and a cam driven by the gear. When the motor is driven by the control device 23, the gear and the cam are driven. The cap displacement section 33 moves the cap section 61 up and down when the gear and the cam are driven.

When the carriage 2 is placed in the maintenance position and the cap part 61 is raised by the cap displacement part 33 with the nozzle 4A and the cap part 61 facing each other, the first lip 61D and the second lip 61E of the cap part 61 is in close contact with the nozzle surface 4B. Thereby, the nozzle 4A is covered with the cap portion 61. That is, the first nozzle 41N is covered by the first cap part 61A, and the second nozzle 42N is covered by the second cap part 61B.

Note that the cap portion 61 is not limited to one that covers the nozzle 4A by coming into close contact with the nozzle surface 4B. The cap portion 61 may cover the nozzle 4A by coming into close contact with a frame (not shown) arranged around the nozzle surface 4B of the inkjet head 4.

The suction section 62 includes a suction pump 62P and a switching section 62V. The suction pump 62P is a tube pump or the like, and is connected to a motor (not shown) through a gear. The switching unit 62V, the suction pump 62P, and the waste liquid storage unit 63 are connected via a tube 64. The switching section 62V is switchably connected to the first cap section 61A and the second cap section 61B via the tube 64. The switching unit 62V is a rubber valve, and is connected to a motor (not shown) through a gear.

The switching unit 62V switches between a flow path from the first cap portion 61A to the suction pump 62P and a flow path from the second cap portion 61B to the suction pump 62P by driving the motor. The suction section 62 selectively discharges ink inside the first cap section 61A and the second cap section 61B using the switching section 62V. That is, the suction section 62 discharges the ink inside the cap section 61.

In the maintenance unit 8, when the suction pump 62P is driven by the control device 23, the ink inside the first cap section 61A and the ink inside the second cap section 61B are discharged to the waste liquid storage section 63. The waste liquid storage section 63 stores ink discharged from the inside of the cap section 61 by the suction section 62. In other words, the waste liquid storage section 63 stores the ink discharged from the inside of the first cap section 61A and the second cap section 61B by the suction section 62.

The first electrode E1 is disposed inside the first cap portion 61A, and ink ejected from the first nozzle 41N can land on the first electrode E1. The second electrode E2 is arranged inside the second cap portion 61B, and the ink ejected from the second nozzle 42N can land on the second electrode E2. When the carriage 2 is placed at the maintenance position, the first electrode E1 faces the first nozzle 41N, and the second electrode E2 faces the second nozzle 42N. The first electrode E1 and the second electrode E2 are arranged inside the cap part 61 and provided on the bottom part 61C.

The liquid ejection device 1 further includes a high voltage circuit 21, a detection section 22, and a control device 23 shown in FIG. The first electrode E1 and the second electrode E2 have a rectangular planar shape, are made of a conductive material, and are connected to the high voltage circuit 21. A predetermined positive potential is applied to the first electrode E1 and the second electrode E2 by the high voltage circuit 21. On the other hand, the inkjet head 4 is connected to the ground GND. Thereby, a predetermined potential difference is generated between the inkjet head 4 and the first electrode E1 and the second electrode E2. High voltage circuit 21 is connected to ground GND.

The detection unit 22 includes a first detection unit 22A and a second detection unit 22B. The first detection unit 22A is electrically connected to the first electrode E1, and detects that ink is ejected from the first nozzle 41N toward the first electrode E1. The second detection unit 22B is electrically connected to the second electrode E2, and detects that ink is ejected from the second nozzle 42N toward the second electrode E2. In the detection of ink by the detection unit 22, a case in which ink lands on the first electrode E1 will be described in detail below. The case where the ink lands on the second electrode E2 is the same as the case where the ink lands on the first electrode E1, so the explanation will be omitted.

The inkjet head 4 is connected to the ground GND, and the potential of the inkjet head 4 is maintained as close to 0V as possible. A potential of 600 V is applied to the first electrode E1 from the high voltage circuit 21. As a result, a potential difference of 600V is generated between the inkjet head 4 and the first electrode E1.

When the inkjet head 4 discharges ink from the first nozzle 41N toward the first electrode E1 with the carriage 2 placed at the maintenance position, the negatively charged ink approaches the first electrode E1. When the ink lands on the first electrode E1, a negative charge is transferred to the first electrode E1, and the voltage value of the first electrode E1 decreases. To explain more simply, a phenomenon similar to that in which current flows from the first electrode E1 to the inkjet head 4 occurs through the ejected ink.

Using such a principle, the detection unit 22 determines whether ink has been ejected from the nozzle 4A to the electrode. Further, in the ink detection described above, it is possible to grasp not only the presence or absence of ejection but also various states of the nozzle 4A. For example, depending on the magnitude of the voltage waveform detected by the detection unit 22 or the magnitude of the time from the output of the ejection signal by the control device 23 until the ink lands, the ink ejected from the inkjet head 4 may be of a normal size. You can check whether or not. The ejection signal is a signal that instructs the inkjet head 4 to eject ink.

Further, based on the detection results by the detection unit 22, it is possible to check whether the nozzle 4A is blocked, the viscosity of the ink has increased, the presence or absence of splashes, the bending of the ink, the state of air bubbles mixed in the ink, etc. Since the status confirmation of these nozzles 4A has no direct relation to this embodiment, detailed explanation thereof will be omitted here.

On the other hand, when ink is not ejected from the first nozzle 41N, the voltage value of the first electrode E1 hardly changes. Note that here, although a positive potential is applied to the first electrode E1 and the second electrode E2 by the high voltage circuit 21, a negative potential is applied to the first electrode E1 and the second electrode E2 by the high voltage circuit 21. may be applied.

Moreover, although the case where the cap part 61 has the 1st cap part 61A and the 2nd cap part 61B was demonstrated here, it is not restricted to this. The cap part 61 may cover all the nozzles 4A at once, and the suction part 62 may discharge the ink inside the cap part 61. In this case, the suction section 62 does not have the switching section 62V and only has the suction pump 62P. Moreover, at least one electrode is arranged inside the cap part 61, and the detection part 22 is connected to the at least one electrode.

Furthermore, even when two or more electrodes are arranged inside the cap part 61, the liquid ejection device 1 may include either one of the first detection part 22A and the second detection part 22B as the detection part 22. good. In this case, the detection unit 22 may be configured to calculate the average value of the voltage values of two or more electrodes and output the average value to the control device 23. Further, the detection unit 22 may be configured to be controlled by the control device 23 so that the detection unit 22 detects ink ejection by shifting the timing at which the detection unit 22 detects each of the voltage values of two or more electrodes.

The cap displacement section 33 is configured to move the cap section 61 up and down by driving a motor, but may be configured to move the carriage 2 or the inkjet head 4 up and down. Thereby, the cap displacement section 33 becomes a mechanism for relatively displacing the cap section 61 by movement of the carriage 2 or the inkjet head 4.

<Electrical configuration of liquid ejection device 1>
FIG. 3 is a block diagram showing the electrical configuration of the liquid ejecting device 1 shown in FIG. 1. As shown in FIG. As shown in FIG. 3, the liquid ejection device 1 includes a carriage motor 31, a conveyance motor 32, and a cap displacement section 33. The operation of the liquid ejection device 1 is controlled by a control device 23.

The control device 23 includes an ASIC (Application Specific Integrated Circuit) 41, a CPU (Central Processing Unit) 42, a ROM (Read Only Memory) 43, a RAM (Random Access Memory) 44, and a flash memory 45. ing. The ASIC 41 and the CPU 42 are examples of a control unit, and the ROM 43, the RAM 44, and the flash memory 45 are examples of a storage unit.

The control device 23 controls the operations of the carriage motor 31, the transport motor 32, the cap displacement section 33, the suction pump 62P, the switching section 62V, the high voltage circuit 21, and the detection section 22. The control device 23 causes the cap displacement section 33 and the suction section 62 to execute a discharge process for discharging the ink remaining inside the cap section 61 . The discharge process corresponds to the tilt contact operation and the idle suction operation, which will be described later.

Further, the liquid ejecting device 1 may further include a display unit (not shown) such as a display, and an operation unit (not shown) including a switch, a touch panel, and the like. The control device 23 also controls the display section, and the operation section sends a signal to the control device 23 according to the operation by the user.

Carriage motor 31 moves carriage 2 along guide rails 9 and 10 in the scanning direction. The conveyance motor 32 conveys the paper P in the conveyance direction by rotating the conveyance rollers 6 and 7. The cap displacement section 33 displaces the first cap section 61A and the second cap section 61B so that the first lip 61D and the second lip 61E are brought into contact with and separated from the inkjet head 4. In other words, the cap displacement section 33 displaces the cap section 61 so that the lip of the cap section 61 comes into contact with and separates from the inkjet head 4 .

<Processing of liquid ejection device 1>
The processing of the liquid ejection device 1 will be described based on FIGS. 4 to 6. FIG. 4 is a diagram showing the suction purge and tilt contact operations performed by the liquid ejection device 1 shown in FIG. 1. FIG. 5 is a graph showing the voltage of the electrodes included in the liquid ejection device 1 shown in FIG. FIG. 6 is a flowchart showing the processing of the liquid ejecting device 1 shown in FIG.

As shown in FIG. 6, first, the control device 23 determines whether a storage command has been received (S1). If the liquid ejection device 1 receives the storage command (YES in S1), the process proceeds to step S2. If the liquid ejection device 1 has not received the storage command (NO in S1), step S1 is repeated.

The control device 23 executes a discharge test (S2). The discharge test will be specifically explained below. Since the control related to the ejection test using the first electrode E1 and the control related to the ejection test using the second electrode E2 are the same, only the control related to the ejection test using the first electrode E1 will be described here.

The control device 23 places the carriage 2 in the maintenance position by driving the carriage motor 31, and applies a potential of 600 V to the first electrode E1 by the high voltage circuit 21. After that, the control device 23 sets one of the first nozzles 41N corresponding to the first electrode E1 as a target nozzle, and drives the drive element corresponding to the target nozzle. The drive element is a piezo element that is driven by the control device 23 to eject ink from the target nozzle.

If the state of the first nozzle 41N is normal, that is, if the first nozzle 41N is not clogged by foreign matter or solidified by clay rising in the ink, ink is ejected from the first nozzle 41N. Ink ejected from the first nozzle 41N lands on the first electrode E1, and the first detection unit 22A detects a change in voltage due to the ink ejection and landing. If the state of the first nozzle 41N is abnormal, ink is not ejected from the first nozzle 41N. If ink is not ejected from the first nozzle 41N, no ink will land on the first electrode E1, so the first detection unit 22A will not detect a change in voltage due to ink landing.

As described above, the control device 23 determines whether the set target nozzle is an abnormal nozzle. The control device 23 changes the setting of the target nozzle to another nozzle, and determines whether or not the changed target nozzle is an abnormal nozzle in the same manner as described above. In other words, the control device 23 determines whether or not all nozzles 4A are abnormal nozzles. The control device 23 stores the number of abnormal nozzles in the RAM 44.

After executing the discharge test, the control device 23 refers to the number of abnormal nozzles from the RAM 44 and determines whether the number of abnormal nozzles among the plurality of nozzles 4A is less than or equal to a predetermined value (S3). The predetermined value is stored in the ROM 43. If the number of abnormal nozzles is less than or equal to the predetermined value (YES in S3), the control device 23 executes storage processing (S4). That is, the control device 23 performs image storage on the paper P as the storage process. If the number of abnormal nozzles is greater than the predetermined value (NO in S3), the process advances to step S5.

The control device 23 causes a suction purge to be performed on the black ink (S5). The suction purge is performed by driving the suction pump 62P by the control device 23 with the plurality of nozzles 4A covered by the cap part 61, thereby purging the ink inside the inkjet head 4 from the plurality of nozzles 4A to the cap part 61. This is a process to discharge waste. Step S5 will be specifically explained below.

The control device 23 drives the switching unit 62V to select the flow path from the second cap portion 61B to the suction pump 62P. As shown by 101 in FIG. 4, the control device 23 drives the cap displacement portion 33 to bring the first lip 61D and the second lip 61E into contact with the nozzle surface 4B. This brings the second nozzle 42N into a state where it is covered by the second cap portion 61B.

The control device 23 drives the suction pump 62P of the suction unit 62 in this state. In this way, the control device 23 drives the suction unit 62 to create a negative pressure inside the second cap unit 61B, so that the black inside the inkjet head 4 is supplied to the second cap unit 61B from the plurality of nozzles 4A. Execute a suction purge to discharge ink.

The control device 23 performs a suction purge on the black ink, and then performs an idle suction operation on the black ink (S6). Details of step S6 will be described later. The control device 23 executes an empty suction operation for black ink, and then executes a suction purge for color ink (S7).

Specifically, the control device 23 drives the switching unit 62V so as to cause the switching unit 62V to select the flow path from the first cap portion 61A to the suction pump 62P. In step S5, since the first lip 61D is in contact with the nozzle surface 4B, the first nozzle 41N is covered by the first cap portion 61A.

The control device 23 drives the suction pump 62P of the suction unit 62 in this state. In this way, the control device 23 drives the suction unit 62 to create a negative pressure inside the first cap unit 61A, so that the color inside the inkjet head 4 is applied to the first cap unit 61A from the plurality of nozzles 4A. Execute a suction purge to discharge ink.

The control device 23 performs a suction purge on the color ink, and then performs an idle suction operation on the color ink (S8). Details of step S8 will be described later. After step S8, the process returns to step S2.

<Impact suction operation for black ink>
FIG. 7 is a flowchart showing a process related to executing an idle suction operation for black ink among the processes shown in FIG. 6, and FIG. 8 is a flowchart showing a continuation of the process shown in FIG. The idle suction operation for black ink described here is an example. In step S6, as shown in FIG. 7, when the idle suction operation for black ink is executed, first, the control device 23 executes the inclined contact operation by driving the cap displacement section 33 (S21 ).

Specifically, first, the control device 23 moves the carriage 2 by driving the carriage motor 31, and moves the inkjet head 4 to the maintenance position. The control device 23 drives the motor of the cap displacement section 33. As a result, the control device 23 controls the cap portion 61 so that a portion of the first lip 61D and the second lip 61E is in contact with the inkjet head 4, and another portion of the first lip 61D and the second lip 61E is in contact with the inkjet head. position in a predetermined posture away from 4. In other words, the control device 23 positions the first cap portion 61A and the second cap portion 61B in the predetermined posture.

The cap portion 61 is positioned as shown in the figures 102 and 103 in FIG. In this case, part of the upper part of the first lip 61D and the second lip 61E comes into contact with the inkjet head 4, and another part of the upper part of the first lip 61D and the second lip 61E is separated from the inkjet head 4.

Note that the diagram indicated by 102 in FIG. 4 is a diagram of the inkjet head 4 and the cap portion 61 viewed from the opposite direction to the Y direction. A diagram indicated by 103 in FIG. 4 is a diagram of the inkjet head 4 and the cap portion 61 viewed from the opposite direction to the X direction. In the diagram indicated by 103 in FIG. 4, the switching unit 62V is omitted. In the diagram indicated by 102 in FIG. 4, the cap portion 61 is inclined so that the upper surface of the cap portion 61 becomes lower as it advances in the Y direction. However, as shown by 103 in FIG. 4, the cap portion 61 may be inclined so that the upper surface of the cap portion 61 becomes higher as it advances in the Y direction.

After the inclined contact operation is performed, the control device 23 drives the switching section 62V to form a flow path from the second cap section 61B to the suction pump 62P (S22). After the flow path from the second cap portion 61B to the suction pump 62P is formed, the control device 23 determines whether to perform optimization processing for the idle suction operation (S23).

The control device 23 may determine whether to perform the optimization process for the idle suction operation based on the user's operation of the above-mentioned operation unit. In this case, the user operates the operating unit so that the control device 23 is set to perform optimization processing for the idle suction operation. On the other hand, the control device 23 may perform an optimization process for the idle suction operation when a predetermined condition set in advance is satisfied.

The predetermined conditions include, for example, that a predetermined period of time has passed since the previous dry suction operation optimization process, and that the time from the start of the dry suction operation to the completion of the dry suction operation in step S27, which will be described later, is specified. An example of this is that the normal suction set time TA, which will be described later, has not been overwritten a predetermined number of times or more. Another example of the predetermined condition is that the collection of data in a table to be described later in which the normal suction setting time TA is associated with each temperature and each suction strength has not been completed.

If the control device 23 determines not to perform the optimization process for the idle suction operation (NO in S23), the control device 23 reads the normal suction set time TA from the flash memory 45 (S24). The control device 23 sets the idle suction operation time to the normal suction set time TA read from the flash memory 45 (S25). The normal suction setting time TA is 4 seconds.

The control device 23 starts driving the suction pump 62P (S26). That is, the control device 23 performs an idle suction operation to drive the suction unit 62 so as to discharge the ink inside the second cap part 61B with the cap part 61 positioned in the predetermined posture. In this way, the idle suction operation is started, and the ink inside the second cap part 61B is discharged to the waste liquid storage part 63. When the normal suction set time TA has elapsed since the start of driving the suction pump 62P, the control device 23 stops driving the suction pump 62P (S27). This completes the idle suction operation for black ink.

Note that when moving to step S27 from steps S32, S35, and S37, which will be described later, the control device 23 sets the time from the start of the dry suction operation to the completion of the dry suction operation, that is, the drive stop of the suction pump 62P, to the normal time. The suction set time TA may be overwritten. In this case, the normal suction set time TA may be stored in the flash memory 45 in association with each temperature and each suction strength, as shown in Table 1 below. Table 1 is an example of a table in which the normal suction setting time TA is associated with each temperature and each suction strength. Similarly, the normal suction setting time TD, which will be described later, may be stored in the flash memory 45 in association with each temperature and each suction strength.

The temperature is a temperature detected by a temperature sensor (not shown) included in the liquid ejection device 1, and the suction strength is, for example, three suction strengths of weak, medium, and strong preset in the liquid ejection device 1. , is the intensity of suction by the suction pump 62P. The suction strength can be set by a user's operation of the operation section. The viscosity of ink changes depending on temperature. The lower the temperature, the higher the viscosity of the ink and the more difficult it is to discharge the ink. Furthermore, the smaller the suction strength, the more difficult it is for ink to be discharged.

Therefore, by storing the normal suction set time TA in association with each temperature and each suction strength, the normal suction set time TA can be appropriately set according to the temperature and the suction strength.

On the other hand, if the control device 23 determines to perform the optimization process for the idle suction operation (YES in S23), the control device 23 reads the first suction time TB from the flash memory 45 and reads the second suction time TC from the ROM 43. is read out (S28). The first suction time TB is set to 1.5 seconds as an initial value, but is changed in step S34, which will be described later. The second suction time TC is 2 seconds.

When the above-mentioned discharge process is executed, the control device 23 sets the time during which the suction unit 62 continues to be driven to the total time of the first suction time TB and the second suction time TC as a predetermined driving time (S29). The first suction time TB is stored in the flash memory 45, and the second suction time TC is stored in the ROM 43, so the predetermined driving time is stored in the storage section described above.

Next, similarly to step S26, the control device 23 starts an idle suction operation and starts detecting remaining liquid for black ink (S30). Specifically, the control device 23 operates the suction pump 62P of the suction section 62 and starts an empty suction operation to discharge the ink inside the second cap section 61B of the cap section 61 to the waste liquid storage section 63.

Further, the control device 23 uses the second detection unit 22B to determine whether or not ink exists between the nozzle surface 4B of the inkjet head 4 and the second electrode E2. Residual liquid detection, which is determined based on the electrical change that occurs between E2 and E2, starts. As the residual liquid detection, as shown in FIG. 5, the second detection section 22B detects the voltage VB of the second electrode E2. The remaining liquid detection will be specifically explained below.

The principle of detecting whether or not ink exists between the nozzle surface 4B of the inkjet head 4 and the second electrode E2 will be explained. A portion of the ink inside the cap portion 61 is gathered toward the Y direction side in the diagram indicated by 103 in FIG. 4, that is, the portion where the second lip 61E is in contact with the nozzle surface 4B.

This is because, as shown by 103 in FIG. 4, when the suction pump 62P is driven, the air flows in from the part that is not in contact with the second lip 61E, and an external force that draws the ink together acts. To be more precise, the ink is in contact with both the inkjet head 4 and the second electrode E2. In this embodiment, this state is called a state in which a liquid column is formed, and this ink is called a liquid column.

When a voltage of 600V is applied to the second electrode E2 with a liquid column formed, the second electrode E2 becomes short-circuited to the inkjet head 4 by the ink, and the voltage of the second electrode E2 becomes lower than 600V. If ink continues to be sucked in this state, the amount of ink will eventually decrease, and the state in which the ink is in contact with both the inkjet head 4 and the second electrode E2, that is, the state in which a liquid column is formed, is eliminated. A change from a state in which a liquid column is not formed to a state in which a liquid column is formed, or from a state in which a liquid column is formed to a state in which a liquid column is not formed is called an electrical change.

In FIG. 5, the vertical axis represents voltage and the horizontal axis represents time. Regarding the vertical axis, the voltage increases as it goes up. The first predetermined time T1 is a time for determining whether or not to forcibly stop driving the suction pump 62P when there is no ink inside the second cap portion 61B. The first reference time TS1 is a time period for preventing the suction pump 62P of the suction unit 62 from continuing to be driven even though a liquid column is not formed.

When there is no ink inside the second cap portion 61B, that is, when a liquid column is not formed, the voltage drop is small. When ink exists inside the second cap portion 61B, that is, when a liquid column is formed, the voltage drop increases and the voltage VB becomes equal to or lower than the second threshold value VS2. If a liquid column is no longer formed due to ink being sucked, the voltage VB becomes larger than the second threshold value VS2.

After the process in step S30, the process proceeds to step S31 shown in FIG. 8 via F1. After the control device 23 starts driving the suction pump 62P of the suction unit 62, when a first predetermined time T1 has elapsed since the start of driving of the suction pump 62P of the suction unit 62, the control device 23 detects the remaining liquid and sets the voltage VB. It is determined whether or not is larger than the second threshold value VS2 (S31).

The reason for this determination is to distinguish between the following two cases. The first case is when the amount of ink inside the second cap portion 61B is smaller than the amount required to form a liquid column when the first predetermined time T1 has elapsed. In this case, wasteful suction is suppressed. The second case is when the amount of ink inside the second cap portion 61B is sufficient to form a liquid column when the first predetermined time T1 has elapsed. The first predetermined time T1 is stored in the ROM 43. The first predetermined time T1 is 1 second.

The fact that the voltage VB is equal to or less than the second threshold value VS2 is synonymous with the fact that a liquid column is formed between the nozzle surface 4B of the inkjet head 4 and the second electrode E2. In other words, a liquid column is formed. In this case, the control device 23 determines that ink is present between the nozzle surface 4B of the inkjet head 4 and the second electrode E2. Moreover, when the voltage VB is larger than the second threshold value VS2, the control device 23 determines that ink is not present between the nozzle surface 4B of the inkjet head 4 and the second electrode E2. In other words, no liquid column is formed.

Consider a case where, when the first predetermined time T1 has elapsed since the start of driving of the suction unit 62, it is determined that the voltage VB is larger than the second threshold value VS2 in the residual liquid detection (YES in S31). In this case, the amount of ink inside the second cap portion 61B is smaller than the amount required to form a liquid column.

If YES in step S31, the control device 23 changes the duration of the idle suction operation after the first predetermined time T1 has elapsed to a second suction time TC that ends the idle suction operation after a certain period of time, and The suction operation is continued (S32). When the second suction time TC elapses after the first predetermined time T1 has elapsed, the process proceeds to step S27 shown in FIG. 7 via F2.

If YES in step S31, the time from the start of the idle suction operation in step S30 to the stop of the suction pump 62P in step S27 is shorter than the total time of the first suction time TB and the second suction time TC. Become. This is because the first suction time TB is longer than the first predetermined time T1. The reason why the first suction time TB is longer than the first predetermined time T1 is that although the first suction time TB is changed in step S34, which will be described later, step S34 is changed from the time when the first predetermined time T1 has elapsed. This is because it will also be executed later.

Furthermore, in the case of YES in step S31, the time from the start of the idle suction operation in step S30 to the drive stop of the suction pump 62P in step S27 is the total time of the first predetermined time T1 and the second suction time TC. The time is therefore shorter than 4 seconds, which is the first reference time TS1, which will be described later.

Therefore, when the first predetermined time T1, which is shorter than the first reference time TS1, has elapsed from the start of driving the suction unit 62, the control device 23 detects that the first electrical state is detected by the second detection unit 22B. stops the driving of the suction pump 62P of the suction unit 62 before reaching the first reference time TS1. The first electrical state is an electrical state corresponding to a state where ink is not present between the inkjet head 4 and the second electrode E2.

In addition, the above configuration can eliminate wasted time in idle suction operation even when the liquid ejection device 1 is installed at an angle or when there are variations in parts for each product of the liquid ejection device 1. Effective. Furthermore, since no time is wasted in idle suction operations, the rotational speed and drive time of the suction pump 62P of the suction section 62 are shortened, so that the life of the suction pump 62P is extended.

Consider a case where it is determined that the voltage VB is equal to or less than the second threshold value VS2 by residual liquid detection when the first predetermined time T1 has elapsed from the start of driving the suction unit 62 (NO in S31). In this case, the amount of ink inside the second cap portion 61B is sufficient to form a liquid column.

Further, the control device 23 continues to drive the suction pump 62P of the suction unit 62, and determines whether the voltage VB has become larger than the second threshold value VS2 by the first reference time TS1 by detecting the remaining liquid. (S33). The reason why this determination is made is that even though the amount of ink inside the second cap portion 61B is smaller than the amount required for forming a liquid column, the suction pump 62P of the suction portion 62 This is to prevent the driving from continuing until the first reference time TS1.

If NO in step S31, the control device 23 determines that if the second electrical state is detected by the second detection unit 22B when the first predetermined time T1 has elapsed since the start of driving the suction unit 62, , the suction unit 62 continues to be driven. The second electrical state is an electrical state corresponding to a state in which ink exists between the inkjet head 4 and the second electrode E2.

According to the above configuration, the control device 23 controls the suction section 62 depending on whether ink is present between the inkjet head 4 and the second electrode E2 when the first predetermined time T1 has elapsed. Change the driving time. Thereby, wasted time related to driving the suction section 62 can be efficiently eliminated.

Consider a case where it is determined that the voltage VB has become larger than the second threshold value VS2 by the residual liquid detection at the change point P1 shown in FIG. 5 by the first reference time TS1 (YES in S33). In this case, the amount of ink inside the second cap portion 61B has become smaller than the amount required to form a liquid column. The change point P1 is a point where the voltage VB changes from a state where it is less than or equal to the second threshold value VS2 to a state where the voltage VB is greater than the second threshold value VS2.

If YES in step S33, the control device 23 overwrites the elapsed time TP from the start of the idle suction operation to the first suction time TB stored in the flash memory 45 (S34). The elapsed time TP from the start of the idle suction operation is the elapsed time from the start of the idle suction operation to the time when the voltage VB becomes larger than the second threshold value VS2.

That is, the control device 23 stores in the flash memory 45 the elapsed time from the start of driving the suction part 62 until the electrical change is detected by the second detection part 22B, and stores the elapsed time stored in the flash memory 45. The next discharge process is executed as part of the predetermined driving time set in step S29.

The electrical change is an electrical change that occurs when ink changes from a state in which ink exists between the inkjet head 4 and the second electrode E2 to a state in which it does not exist. A part of the predetermined drive time set in step S29 is the first suction time TB. According to the above configuration, since the predetermined drive time is set in memory, the precision of the predetermined drive time is improved and time wasted in driving the suction section 62 is eliminated.

The control device 23 changes the duration of the idle suction operation after the time when the voltage VB becomes larger than the second threshold value VS2 to the second suction time TC, and continues the idle suction operation (S35). When the second suction time TC has elapsed from the time when the voltage VB became larger than the second threshold value VS2, the process proceeds to step S27 shown in FIG. 7 via F2.

If YES in step S33, the time from the start of the empty suction operation in step S30 to the stop of the suction pump 62P in step S27 is shorter than the first reference time TS1. When the voltage VB changes from a state in which it is less than or equal to the second threshold value VS2 to a state in which the voltage VB becomes greater than the second threshold value VS2, the amount of ink inside the second cap portion 61B decreases depending on the time period of the idle suction operation. This is because the amount is such that it does not reach one reference time TS1.

Consider a case where the second detection section 22B detects the electrical change after the start of driving the suction section 62 until the first reference time TS1 has elapsed. In this case, the control device 23 stops driving the suction section 62 before reaching the first reference time TS1.

According to the above configuration, when the second detection section 22B detects the electrical change, the control device 23 stops driving the suction section 62 before reaching the first reference time TS1. This prevents the suction section 62 from being driven in the absence of ink, eliminating wasted time associated with driving the suction section 62.

If the state in which the voltage VB is equal to or lower than the second threshold value VS2 is maintained (NO in S33), the control device 23 determines whether the first reference time TS1 has elapsed since the start of driving the suction unit 62. (S36). If NO in step S33, it means that the amount of ink inside the second cap portion 61B is maintained at a sufficient amount to form a liquid column.

Further, the reason why the determination in step S36 is made is as follows. Even though the amount of ink inside the second cap portion 61B is smaller than the amount required to form a liquid column, the state in which the voltage VB is equal to or lower than the second threshold value VS2 continues. There are cases. In such a case, the suction pump 62P of the suction unit 62 is prevented from continuing to be driven.

The first reference time TS1 is stored in the ROM 43 as a time longer than the first predetermined time T1. The first reference time TS1 is 4 seconds. If the first reference time TS1 has not elapsed (NO in S36), the process returns to step S33.

If the first reference time TS1 has elapsed (YES in S36), the control device 23 continues the dry suction operation without changing the time of the dry suction operation after the first reference time TS1 has elapsed. Further, if the predetermined drive time set in step S29 has passed since the start of the idle suction operation, the control device 23 ends the idle suction operation when the first reference time TS1 has elapsed (S37). That is, the process proceeds to step S27 shown in FIG. 7 via F2.

If YES in step S36, the time from the start of the idle suction operation in step S30 until the drive of the suction pump 62P stops in step S27 is the same as the first reference time TS1. Consider a case where the second detection section 22B does not detect the electrical change after the suction section 62 starts to be driven until the first reference time TS1 elapses. In this case, the control device 23 drives the suction unit 62 until the first reference time TS1. As shown in steps S28 to S37, the time for the idle suction operation is optimized according to the value of the voltage VB of the second electrode E2, so that the time for the idle suction operation can be efficiently shortened.

<Impact suction operation for color ink>
The idle suction operation for color ink in step S8 described here is an example. Here, only the portions in which the idle suction operation for color ink is different from the idle suction operation for black ink will be explained. Except for the parts described below, the idle suction operation for color ink is the same as the idle suction operation for black ink. For convenience of explanation, in the description of the empty suction operation for color ink, reference will be made to FIGS. 7 and 8, and for step numbers, the same numbers as for the empty suction operation for black ink will be referred to.

In step S22, the control device 23 drives the switching section 62V to form a flow path from the first cap section 61A to the suction pump 62P. In steps S24 to S27, in the idle suction operation for color ink, the normal suction set time TD is used instead of the normal suction set time TA. The normal suction setting time TD is 8 seconds.

Moreover, in steps S28, S29, S32, S34, and S35, the first suction time TB and the second suction time TC are replaced with the third suction time TE and the fourth suction time TF. The third suction time TE is set to 3.5 seconds as an initial value. The fourth suction time TF is 3 seconds.

In step S30, the control device 23 starts an idle suction operation and starts detecting remaining liquid for color ink. Specifically, the control device 23 operates the suction pump 62P of the suction section 62 and starts an empty suction operation to discharge the ink inside the first cap section 61A of the cap section 61 to the waste liquid storage section 63.

Further, in step S30, the control device 23 uses the first detection unit 22A to determine whether ink is present between the nozzle surface 4B of the inkjet head 4 and the first electrode E1. Residual liquid detection, which is determined based on the electrical change that occurs between the first electrode E1, is started. As residual liquid detection, the first detection unit 22A detects the voltage VA of the first electrode E1.

In steps S31 and S33, the first predetermined time T1 is replaced by a second predetermined time T2, the voltage VB is replaced by a voltage VA, and the second threshold VS2 is replaced by a first threshold VS1. The second predetermined time T2 is 1 second. In step S36, the first reference time TS1 is replaced by the second reference time TS2. The second reference time TS2 is 7 seconds.

The present invention is not limited to the embodiments described above, and various changes can be made within the scope of the claims, and the present invention also applies to configurations obtained by appropriately combining technical means disclosed in the embodiments. included in the technical scope of

1 Liquid ejection device 4 Inkjet head (head unit)
4A Nozzle 22 Detection section 22A First detection section 22B Second detection section 23 Control device 33 Cap displacement section 41N First nozzle 42N Second nozzle 43 ROM (storage section) 45 Flash memory (storage section)
61 Cap part 61A First cap part 61B Second cap part 61D First lip 61E Second lip 62 Suction part 63 Waste liquid storage part E1 First electrode E2 Second electrode T1 First predetermined time T2 Second predetermined time TS1 First standard Time TS2 2nd standard time

Claims (3)

a head unit having at least one nozzle for discharging liquid;
a cap portion for sealing the nozzle of the head unit and having a lip;
a cap displacement section that displaces the cap section so that the lip of the cap section comes into contact with and separates from the head unit;
an electrode disposed inside the cap portion, on which liquid ejected from the nozzle can land;
a detection unit that is electrically connected to the electrode and detects that liquid is ejected from the nozzle toward the electrode;
a suction unit that discharges the liquid inside the cap unit;
a waste liquid storage section that stores the liquid discharged from the inside of the cap section by the suction section;
a control unit that executes a discharge process of discharging the liquid remaining inside the cap unit by driving the cap displacement unit and the suction unit;
The control unit includes:
By driving the cap displacement portion, the cap portion is positioned in a predetermined posture in which a portion of the lip is in contact with the head unit and another portion of the lip is separated from the head unit;
driving the suction unit to discharge the liquid inside the cap unit while the cap unit is positioned in the predetermined position;
Electricity generated by the detection unit changing from a state in which liquid exists between the head unit and the electrode to a state in which it does not exist during a period from when the suction unit starts to be driven until a reference time elapses. If a change in the liquid is detected, the drive of the suction unit is stopped before the reference time is reached, and the detection unit changes the state in which the liquid exists between the head unit and the electrode to the state where it does not exist. If an electrical change caused by the change is not detected, the liquid ejecting device drives the suction section to the reference time. After starting the drive of the suction unit, the control unit is configured to cause the detection unit to cause the liquid to flow between the head unit and the electrode when a predetermined time shorter than the reference time has elapsed since the start of the drive of the suction unit. If an electrical state corresponding to a state existing between the head unit and the electrode is detected, the suction section continues to be driven, and the detection section corresponds to a state in which liquid does not exist between the head unit and the electrode. 2. The liquid ejecting device according to claim 1, wherein if an electrical state is detected, driving of the suction section is stopped before the reference time is reached. Further equipped with a storage section,
The control unit includes:
When executing the discharge process, setting the time for which the suction unit continues to be driven to a predetermined driving time stored in the storage unit,
The elapsed time from the start of driving of the suction unit until the detection unit detects an electrical change caused by a change from a state in which liquid exists between the head unit and the electrode to a state in which the liquid does not exist; stored in the storage unit,
The liquid ejection device according to claim 1 or 2, wherein the elapsed time stored in the storage unit is used as part of the predetermined driving time to execute the next ejection process.

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