JP7600759B2 - Liquid ejection device - Google Patents

Description

The present invention relates to a liquid ejection device equipped with a liquid ejection head having nozzles for ejecting liquid.

There is known a liquid ejection device that performs a recording operation by ejecting ink (liquid) stored in a liquid storage chamber from a liquid ejection head onto a recording medium. The liquid ejection device (liquid ejection device) of Patent Document 1 includes a cover member for reducing the load on a negative pressure pump that maintains negative pressure in the flushing box during flushing of the liquid ejection head (liquid ejection head). This makes it possible to prevent the ink ejected from the liquid ejection head into the flushing box by flushing from scattering outside the flushing box in the form of mist.

The inkjet recording device (liquid ejection device) of Patent Document 2 has an atmosphere release electromagnetic valve that controls communication between the upper air layer in the ink buffer (liquid storage chamber) and the atmosphere. The atmosphere release electromagnetic valve is open while ink is being supplied to the ink buffer. This allows the air in the upper part of the ink buffer to escape when ink is being supplied, and the ink in the ink buffer is not pressurized. In addition, in this inkjet recording device, the atmosphere release electromagnetic valve is closed during purging, and pressurized ink is supplied from the ink tank to perform the purging operation.

JP 2010-260309 A Japanese Patent Application Publication No. 1-46081

In the devices of Patent Documents 1 and 2, some of the ink ejected from the liquid ejection head and the ink stored in the liquid storage chamber evaporates and adheres as mist to the movable member of the valve in the liquid storage chamber and/or its surrounding members. When the mist that adheres to the movable member of the valve and/or its surrounding members condenses, it becomes a resistance when the movable member is displaced, so as the amount of mist that adheres increases, the load when driving the valve increases, and it may become difficult to perform appropriate opening and closing operations.

The object of the present invention is to provide a liquid ejection device that can reliably control the opening and closing of a valve even if the load when driving the valve increases due to the influence of mist.

The liquid ejection device according to the present invention comprises a liquid ejection head having a nozzle for ejecting liquid, a liquid storage chamber for storing liquid, an atmosphere communication passage for connecting the liquid storage chamber to the outside, and a liquid storage unit having a valve for electrically opening and closing the atmosphere communication passage, and a control unit for supplying a current to drive the valve, and the control unit counts at least one of the values of the number of times the liquid is ejected by the liquid ejection head, the ejection amount, the number of printed sheets, and the age of the liquid ejection head, and increases the current value supplied to the valve when a related value related to the counted value exceeds a predetermined threshold value.

According to the present invention, when the number of liquid ejections, ejection amount, number of printed sheets, or aging increases, mist generated by evaporation of the liquid ejected from the nozzle or the liquid inside the liquid storage chamber adheres to the valve. According to the present invention, when the amount of mist generated increases and the load when driving the valve increases, the current value supplied to drive the valve can be increased. Therefore, even if the load when driving the valve increases due to the influence of the mist, the current value required to drive the valve can be supplied, and the valve can be reliably driven.

1 is a schematic configuration diagram of a printer according to a first embodiment of the present invention; 2 is a vertical sectional view showing a schematic internal structure of the printer shown in FIG. 1 . FIG. 3 is a side view of the ink tank and the inkjet head shown in FIG. 2 . FIG. 2 is a block diagram showing the electrical configuration of the printer shown in FIG. 1 . 4 is a table showing current values supplied to electromagnetic valves in the first embodiment. 10 is a table showing current values supplied to electromagnetic valves in the second embodiment.

First Embodiment
A printer 1 (liquid ejection device of the present invention) according to a first embodiment of the present invention will be described below with reference to Figures 1 to 7. The up-down, left-right, and front-rear directions shown in Figure 1 are the up-down, left-right, and front-rear directions of the printer 1.

(Overall configuration of printer 1)
As shown in FIG. 1, the printer 1 has a housing 11 that is generally rectangular. An opening 12 is formed in the approximate center of a front wall 11a of the housing 11. A paper feed tray 15 and a paper discharge tray 16 are provided in the opening 12 in two stages, one above the other. The paper feed tray 15 is configured to be insertable and removable in the front-rear direction from the opening 12, that is, to be detachable from the housing 11. Paper P (recording medium of the present invention) of a desired size (e.g., A4 size) is placed on the paper feed tray 15. The printer 1 can be connected to an external device such as a personal computer (hereinafter referred to as a PC). Then, the printer 1 executes a recording operation based on recording data from the PC or the like.

As shown in FIG. 1, an operation unit 13 is provided on the upper part of the front wall 11a. The operation unit 13 is composed of buttons that are operated for various settings, a liquid crystal display that displays various information, and the like. In this embodiment, the operation unit 13 is composed of a touch panel that has the functions of both buttons and a liquid crystal display.

As shown in Figs. 1 and 2, the housing 11 has an opening/closing cover 14 that forms the ceiling portion. The opening/closing cover 14 is configured to be rotatable around a rotation axis (not shown) that runs along the left-right direction at the rear end. By opening the opening/closing cover 14, an ink tank 61 (described below) is exposed, making it possible to inject ink into the ink tank 61 and refill it.

(Internal structure of printer 1)
Next, a description will be given of the internal structure of the printer 1. As shown in FIG.

The transport mechanism 20 has a feeding section 50, a transport path 52, a pair of transport rollers 53, and a pair of discharge rollers 54. As shown in FIG. 2, the feeding section 50 feeds the paper P placed on the paper feed tray 15 to the transport path 52. The pair of transport rollers 53 transports the paper P fed by the feeding section 50 to the recording section 30. The recording section 30 has, for example, an inkjet recording system configuration, and records an image on the paper P transported by the pair of transport rollers 53. The pair of discharge rollers 54 discharges the paper P recorded by the recording section 30 to the discharge tray 16.

As shown in FIG. 2, the feed unit 50 is provided above the paper feed tray 15. The feed unit 50 has a paper feed roller 50a and an arm 50b. The paper feed roller 50a is rotatably supported at the tip of the arm 50b. The arm 50b is rotatably supported on a support shaft 50c and is biased by a spring or the like to rotate the paper feed roller 50a downward so that it contacts the paper feed tray 15. The arm 50b is also configured to be able to retract upward when the paper feed tray 15 is attached or detached. The paper feed roller 50a is driven to rotate by a paper feed motor 91M (see FIG. 5), and paper P loaded in the paper feed tray 15 is fed to the transport path 25.

As shown in FIG. 2, the paper feed tray 15 has an inclined wall portion 15a. The inclined wall portion 15a guides the paper P placed in the paper feed tray 15 to the transport path 52 when the paper P is fed by the paper feed roller 50a.

The transport path 52 is configured inside the housing 11, and as shown in FIG. 2, it bends upward from the rear end of the paper feed tray 15 and toward the front of the printer 1. The paper P fed from the paper feed tray 15 is guided by the transport path 52 to make a U-turn from the bottom to the top and reaches the recording unit 30.

The pair of transport rollers 53 has a transport roller 53a arranged on the lower side and a pinch roller 53b arranged on the upper side. The transport roller 53a is driven to rotate by a transport motor 92M (see FIG. 5). The pinch roller 53b rotates as the transport roller 53a rotates. The transport roller 53a and the pinch roller 53b cooperate to pinch the paper P from above and below, and transport the paper P to the recording unit 30.

The pair of discharge rollers 54 has a discharge roller 54a arranged on the lower side and a spur roller 54b arranged on the upper side. The discharge roller 54a is driven to rotate by a discharge motor 93M (see FIG. 5). The spur roller 54b rotates with the rotation of the discharge roller 54a. The discharge roller 54a and the spur roller 54b cooperate to hold the paper P from above and below, and transport the paper P to the discharge tray 16.

In this embodiment, the transport direction of the paper P is the direction in which the paper P is transported from the paper feed tray 15 by the transport mechanism 20, and is the direction of the solid arrow in FIG. 2. Specifically, the transport direction of the paper P is the direction in which the paper P is fed from the front to the rear by the paper feed roller 50a, guided to make a U-turn by the transport path 52, and further fed from the rear to the front by the transport roller pair 53 and the paper discharge roller pair 54.

2, the recording unit 30 has an inkjet head 31 (liquid ejection head of the present invention), four ink tanks 61 (liquid storage units of the present invention), a carriage 70, a moving mechanism 71, and a platen 17. The carriage 70 moves back and forth in the scanning direction (a left-right direction that intersects with the transport direction of the paper P). The inkjet head 31 and the ink tanks 61 are supported by the carriage 70. In other words, the printer 1 in this embodiment is a so-called on-carriage type in which the ink tanks 61 and the inkjet head 31 are mounted on the carriage 70. In this embodiment, the ink tanks 61 are entirely located above the inkjet head 31. However, this is not limited to this, and a part of the ink tanks 61 may be located above the upper surface of the inkjet head 31, and the remaining part may be located below the upper surface.

As shown in FIG. 3, each ink tank 61 has a tank body 62, a cap 63, an air communication passage 64, and an electromagnetic valve 65. The tank body 62 has a substantially rectangular parallelepiped shape, and has an ink storage chamber 62a (liquid storage chamber of the present invention) formed therein for storing ink. Each ink storage chamber 62a stores magenta, cyan, yellow, and black (M, C, Y, B) ink. The tank body 62 is mainly made of a light-transmitting material (e.g., transparent or translucent resin). This allows the user to visually check the amount of ink in the ink storage chamber 62a.

As shown in FIG. 3, the tank body 62 has a through hole 62c that penetrates its upper wall 62b. The through hole 62c is formed in the center of the upper wall 62b in the left-right direction, slightly toward the front. A cylinder 66 is fitted into the through hole 62c. The cylinder 66 has an ink inlet 67 at its upper end. The ink inlet 67 is an opening that opens upward (i.e., toward the outside). The inner surface of the cylinder 66 defines an ink supply path 66a that extends from the ink inlet 67 to the ink storage chamber 62a. This allows the ink inlet 67 to communicate with the ink storage chamber 62a.

The cap 63 is made of, for example, a flexible resin, and is capable of sealing the ink inlet 67. The cap 63 can be attached and detached to the upper end of the cylinder 66 by user operation, and closes or opens the ink inlet 67. Note that the ink inlet 67 is normally closed by the cap 63, and is opened when ink is injected into the ink storage chamber 62a.

As shown in FIG. 3, the tank body 62 has an air communication passage 64 that penetrates the upper wall 62b and connects the ink storage chamber 62a to the outside. The air communication passage 64 is formed at the rear of the upper wall 62b, in the center in the left-right direction.

The electromagnetic valve 65 is a valve for opening and closing the atmosphere communication passage 64. The electromagnetic valve 65 is disposed above the carriage 70. The electromagnetic valve 65 is a two-way electromagnetic valve, and has a valve portion 65a and a solenoid portion 65b. The valve portion 65a is disposed in the ink storage chamber 62a, and has an internal flow path (not shown) that communicates with the atmosphere communication passage 64 and the ink storage chamber 62a, and a valve (not shown) that opens and closes the internal flow path. When the solenoid portion 65b is driven under the control of the control unit 40, the valve portion 65a of the electromagnetic valve 65 moves in the forward and backward directions, opening and closing the atmosphere communication passage 64.

The tank body 62 also has an outlet 62h that penetrates the bottom wall 62g and allows the ink in the ink storage chamber 62a to flow out to the inkjet head 31. The outlet 62h is located in the center of the bottom wall 62g in the left-right direction, near the front end.

The inkjet head 31 has an internal flow path (not shown) to which ink is supplied from the ink tank 61. As shown in FIG. 3, the inkjet head 31 ejects ink from a plurality of nozzles 32 formed on its lower surface, the nozzle surface 31a. More specifically, the nozzles 32 form a nozzle row that runs in the front-rear direction along the transport direction of the paper P. Ink is ejected from the nozzles 32. In this embodiment, the inkjet head 31 is capable of ejecting ink droplets of three sizes, large, medium, and small, from the nozzles 32.

As shown in FIG. 3, the inkjet head 31 is connected to the ink tank 61 via a connection member 69. The connection member 69 is formed with a communication passage (liquid flow passage) 69a that connects the outlet 62h to the internal flow passage of the inkjet head 31. This allows the ink stored in the ink storage chamber 62a of the ink tank 61 to be supplied to the inkjet head 31.

The platen 17 is disposed below the inkjet head 31 and supports the paper P from below as it is transported by the transport roller pair 53. The platen 17 is disposed in the portion of the reciprocating movement range of the carriage 70 through which the paper P passes. The width of the platen 17 is sufficiently larger than the maximum width of the paper P that can be transported, so the paper P transported along the transport path 52 always passes over the platen 17.

As shown in FIG. 2, the movement mechanism 71 includes a pair of guide rails 72 and a belt transmission mechanism (not shown). The pair of guide rails 72 are arranged at a distance from each other in the front-rear direction and extend parallel to each other in the left-right direction. The carriage 70 is arranged to straddle the pair of guide rails 72. The carriage 70 is connected to a carriage motor 94M (see FIG. 5) via the belt transmission mechanism, and driving the carriage motor 94M drives the belt transmission mechanism. This causes the carriage 70 to move in the scanning direction (left-right direction) along the pair of guide rails 72, moving the inkjet head 31 along the left-right direction.

The inkjet head 31 ejects ink from the nozzles 32 under the control of the control unit 40 based on the recording data. In other words, the inkjet head 31 scans the paper P as the carriage 70 moves back and forth in the left-right direction, and ejects ink from the nozzles 32 to record an image on the paper P transported on the platen 17. The printer 1 is provided with a linear encoder (not shown) having a number of light-transmitting sections (slits) arranged at intervals in the scanning direction. The carriage 70 is provided with a transmission-type position detection sensor (not shown) having a light-emitting element and a light-receiving element. The printer 1 is capable of recognizing the current position of the carriage 70 in the scanning direction from the count value of the light-transmitting sections of the linear encoder detected by the position detection sensor while the carriage 51 is moving, and the rotational drive of the carriage motor 94M is controlled.

The control unit 40 includes a CPU (Central Processing Unit) 131, an ASIC (Application Specific Integrated Circuit) 135, and a memory 140. The CPU 131, the ASIC 135, and the memory 140 are connected by an internal bus 137. The memory 140 includes a ROM (Read Only Memory) 132, a RAM (Random Access Memory) 133, and an EEPROM (Electrically Erasable Programmable Read-Only Memory) 134. The ROM 132 stores programs for controlling various operations of the printer 1. The CPU 131 executes the programs using the RAM 133 and the EEPROM 134.

The ASIC 135 outputs control signals to the inkjet head 31, the electromagnetic valve 65, the paper feed motor 91M, the transport motor 92M, the paper discharge motor 93M, the carriage motor 94M, etc., and controls their operation. For example, the control unit 40 controls the inkjet head 31, the paper feed motor 91M, the transport motor 92M, the paper discharge motor 93M, the carriage motor 94M, etc., based on recording data transmitted from an external device (e.g., a PC or a smartphone), alternately executing a transport process and a recording process, and recording an image, etc., on the paper P. The control unit 40 also supplies a current of an arbitrary current value to the electromagnetic valve 65, and controls the opening and closing operation of the electromagnetic valve 65.

The conveying process is a process in which the conveying roller pair 53 and the discharge roller pair 54 convey the paper P by a predetermined line feed amount. The control unit 40 controls the conveying motor 92M and the discharge motor 93M to cause the conveying roller pair 53 and the discharge roller pair 54 to execute the conveying process. The recording process is a process in which the inkjet head 31 is controlled to eject ink droplets from the nozzle 32 while moving the carriage 70 along the left-right direction. The control unit 40 then stops the conveying of the paper P for a certain period between the current conveying process and the next conveying process, and executes the recording process while the conveying of the paper P is stopped. In other words, in the recording process, the control unit 40 executes one pass to eject ink droplets from the nozzle 32 while moving the carriage 70 to the right or left. This executes one pass of image recording on the paper P. The control unit 40 can record images on the entire image-recordable area of the paper P by alternately and repeatedly executing the conveying process and the recording process. In other words, the control unit 40 records an image on one sheet of paper P in multiple passes.

In this embodiment, the control unit 40 has one CPU and one ASIC, but the control unit 40 may include only one ASIC, which performs all the necessary processing, or it may include multiple ASICs, which share the necessary processing.

Furthermore, the ASIC 135 of the control unit 40 includes a counting unit 150 that counts a combination of the value of the ink ejection amount by the inkjet head 31 and the value of the age of the inkjet head 31 (see FIG. 4). Here, as described above, the inkjet head 31 can eject ink droplets of three sizes from the nozzle 32. In this embodiment, the counting unit 150 counts the ejection amount value of the ink droplets of the size that is most likely to become mist among the three sizes of ink droplets ejected by the inkjet head 31. The size that is most likely to become mist may be, for example, a small size, a medium size, a large size, or two of the three sizes. The size of the ink droplets that is most likely to become mist is appropriately determined depending on conditions such as the type of ink and the external environment. The counting unit 150 may count the total ejection amount value of ink droplets of all sizes. Hereinafter, when we simply refer to the "amount of ink ejected by the inkjet head 31," this includes both the amount of ink ejected of the size that is most likely to become mist, and the total amount of ink ejected of all sizes of ink droplets.

As shown in FIG. 5, the memory 140 of the control unit 40 stores a table 90 indicating current values (A) corresponding to combinations of the ink ejection volume value by the inkjet head 31 and the age value of the inkjet head 31. In table 90, the vertical axis indicates the ink ejection volume (mL) by the inkjet head 31, and the horizontal axis indicates the age (years) of the inkjet head 31. The current values (A) indicated by table 90 increase as the ink ejection volume (mL) value increases, and increase as the age (years) of the inkjet head 31 increases. The current values (A) indicated by table 90 have an upper limit of 1.2 A.

In this embodiment, each value of the ink ejection volume (mL) listed on the vertical axis of table 90 and each value of the age (years) listed on the horizontal axis correspond to the "predetermined threshold" in the present invention. In other words, in this embodiment, multiple predetermined thresholds are provided.

The control unit 40 increases the current value supplied to the electromagnetic valve 65 to drive the opening and closing operation of the electromagnetic valve 65 so that the current value corresponds to the two values counted by the counting unit 150 in the table 90. For example, if the ink ejection volume value of the inkjet head 31 is 600 mL and the inkjet head 31 has an age value of 4 years, the control unit 40 sets the current value supplied to the electromagnetic valve 65 to 0.6 A based on the table 90. In this embodiment, the control unit 40 is configured to increase the current value supplied to the electromagnetic valve 65 when both the ink ejection volume value and the inkjet head 31 age value exceed their respective "predetermined threshold values."

In this embodiment, the value counted by the counting unit 150 itself corresponds to the "associated value related to the counted value" in the present invention. Note that the control unit 40 may convert the counted value into an associated value by substituting the counted value into a predetermined conversion formula.

As described above, in the printer 1 of this embodiment, the control unit 40 counts the value of the ink ejection amount by the inkjet head 31 and the value of the age of the inkjet head 31, and increases the current value supplied to the electromagnetic valve 65 when the counted value exceeds a predetermined threshold. When the value of the ink ejection amount and the value of the age of the inkjet head 31 increase, mist generated by the ink ejected from the nozzle 32 and the evaporation of the ink inside the ink storage chamber 62a adheres to the electromagnetic valve 65. According to this embodiment, when the amount of mist generated increases and the load when driving the electromagnetic valve 65 increases, the current value supplied to drive the electromagnetic valve 65 can be increased. Therefore, even if the load when driving the electromagnetic valve 65 increases due to the influence of the mist, the current value required to drive the electromagnetic valve 65 can be supplied, and the electromagnetic valve 65 can be reliably driven.

In addition, in this embodiment, the inkjet head 31 ejects ink droplets of three sizes. The control unit 40 counts the value of the ejection amount of the ink droplets of the size that is most likely to become mist among the three sizes of ink droplets ejected by the inkjet head 31, and increases the current value supplied to the electromagnetic valve 65 when the counted value exceeds a predetermined threshold. The ink droplets ejected from the inkjet head 31 include sizes that are likely to become mist and sizes that are not likely to become mist. If the ejection amount values of ink droplets of all sizes are counted and the current value supplied to the electromagnetic valve 65 is increased corresponding to the counted value, power consumption will increase more than necessary. According to this embodiment, in the printer 1 including the inkjet head 31 that ejects ink droplets of three sizes, the value of the ejection amount of the ink droplets of the size that is most likely to become mist is counted, and when the ejection amount value exceeds a predetermined threshold, the current value supplied to the electromagnetic valve 65 is increased. Therefore, compared to the case where ink droplets of all sizes are counted, the current value supplied to the electromagnetic valve 65 does not need to be increased more than necessary, which saves energy.

In addition, in this embodiment, multiple predetermined thresholds are provided. This allows the current value supplied to the electromagnetic valve 65 to be increased in stages. This makes it possible to supply the current value required to drive the electromagnetic valve 65, ensuring that the electromagnetic valve is driven, while also saving energy because there is no need to increase the current value more than necessary.

Furthermore, in this embodiment, the control unit 40 counts the combination of the value of the ink ejection amount by the inkjet head 31 and the value of the age of the inkjet head 31, and increases the current value supplied to the electromagnetic valve 65 when both of the counted values exceed a predetermined threshold value. The amount of mist that adheres to the electromagnetic valve 65 is precisely determined by both the value of the ink ejection amount by the inkjet head 31 and the value of the age of the inkjet head 31. In this embodiment, the current value supplied to the electromagnetic valve 65 is determined according to the combination of the value of the ink ejection amount and the value of the age of the inkjet head 31. Therefore, the current value required to drive the electromagnetic valve 65 can be supplied in a form that better reflects the effect of the mist on the valve drive of the electromagnetic valve 65, and the electromagnetic valve 65 can be driven more reliably.

In addition, in this embodiment, the control unit 40 has a table 90 that indicates current values corresponding to combinations of the ink ejection volume value of the inkjet head 31 and the aging value of the inkjet head 31. The control unit 40 then increases the current value supplied to the electromagnetic valve 65 so that it becomes a current value corresponding to the two counted values in the table 90. In this way, the current value supplied to the electromagnetic valve 65 can be set to the current value shown in the table 90, making it easier to supply the current value required to drive the electromagnetic valve 65.

In this embodiment, the printer further includes a carriage 70 that supports the inkjet head 31 and the ink storage chamber 62a, and a movement mechanism 71 that moves the carriage 70 in the left-right direction. The electromagnetic valve 65 is disposed above the carriage 70. If the electromagnetic valve 65 is disposed above the carriage 70, more mist is likely to adhere to the electromagnetic valve 65, and the load when driving the electromagnetic valve 65 is likely to increase. According to this embodiment, in a printer 1 configured such that the electromagnetic valve 65 is disposed above the carriage 70, even if the load when driving the electromagnetic valve 65 increases due to the influence of the mist, the power required to drive the electromagnetic valve 65 can be supplied, and the electromagnetic valve 65 can be reliably driven.

Furthermore, in this embodiment, the valve that electrically opens and closes the air communication passage 64 is an electromagnetic valve 65. In a printer 1 that employs an electromagnetic valve 65 as a valve that opens and closes electrically, even if the load when driving the electromagnetic valve 65 increases due to the influence of mist, the current value required to drive the electromagnetic valve 65 can be supplied, and the electromagnetic valve 65 can be driven reliably.

Second Embodiment
Next, a printer according to the second embodiment will be described below with reference to Fig. 6. In the following description, the same components as those in the first embodiment will be designated by the same reference numerals, and description thereof will be omitted. The printer according to the second embodiment has the same configuration as the printer 1 according to the first embodiment, except for the value counted by the counting unit 150. In the printer according to the second embodiment, the counting unit 150 counts a combination of the value of the number of sheets of paper P printed by the inkjet head 31 and the value of the age of the inkjet head 31.

As shown in FIG. 6, the memory 140 also stores a table 190 showing current values corresponding to combinations of the number of sheets of paper P printed by the inkjet head 31 and the age of the inkjet head 31. In table 190, the vertical axis shows the number of sheets of paper P printed by the inkjet head 31, and the horizontal axis shows the age of the inkjet head 31. The current value (A) shown in table 190 increases as the number of sheets of paper P printed increases, and increases as the age of the inkjet head 31 increases. The current value (A) shown in table 190 has an upper limit of 1.2 A.

In this embodiment, each value of the number of sheets of paper P (sheets) listed on the vertical axis of table 190 and each value of the age (years) listed on the horizontal axis correspond to the "predetermined threshold" in the present invention. In other words, in this embodiment, multiple predetermined thresholds are provided.

The control unit 40 adjusts the current value supplied to the electromagnetic valve 65 to a current value corresponding to the two values counted by the counting unit 150 in the table 190. For example, if the value of the number of sheets of paper P printed by the inkjet head 31 is 22,000 sheets and the value of the age of the inkjet head 31 is 5 years, the control unit 40 sets the current value supplied to the electromagnetic valve 65 to 0.9 A based on the table 190. In this embodiment, the control unit 40 is configured to increase the current value supplied to the electromagnetic valve 65 when both the value of the number of sheets of paper P printed and the value of the age of the inkjet head 31 exceed the "predetermined threshold value."

The amount of mist that adheres to the electromagnetic valve 65 is precisely determined by both the number of sheets of paper P printed by the inkjet head 31 and the age of the inkjet head 31. In the second embodiment, the current value supplied to the electromagnetic valve 65 is determined according to a combination of the number of sheets of paper P printed and the age of the inkjet head 31. Therefore, the current value required to drive the electromagnetic valve 65 can be supplied in a manner that better reflects the effect of the mist on the valve drive of the electromagnetic valve 65, and the electromagnetic valve 65 can be driven more reliably.

Furthermore, the control unit 40 increases the current value supplied to the electromagnetic valve 65 so that it becomes a current value corresponding to the two counted values in table 190. In this way, the current value supplied to the electromagnetic valve 65 can be set to the current value shown in table 190, making it easier to supply the current value required to drive the electromagnetic valve 65.

(Modification)
Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications are possible within the scope of the patent invention.

In the first embodiment, the counting unit 150 counts the value of the ejection amount of the ink droplets of the size that is most likely to become mist among the three sizes of ink droplets. However, the counting unit 150 may count the value of the ejection amount of the ink droplets of the three sizes for each size. In this case, the control unit 40 converts the value counted for each size into a related value corresponding to each size. For example, the related value corresponding to the large size is a value obtained by multiplying the value of the ejection amount of the large size ink droplet by 3, the related value corresponding to the medium size is a value obtained by multiplying the value of the ejection amount of the medium size ink droplet by 2, and the related value corresponding to the small size is a value obtained by multiplying the value of the ejection amount of the small size ink droplet by 1. Any method of conversion to the related value corresponding to each size may be used, and is appropriately set by the manufacturer or user. The amount of mist generated varies depending on the size of the ink droplets ejected from the inkjet head 31. According to the above configuration, the amount of mist generated, which differs depending on the size of the ink droplets, can be more accurately predicted. Therefore, even if the load when driving the solenoid valve 65 increases due to the influence of mist, the current value required to drive the solenoid valve 65 can be supplied, so the solenoid valve 65 can be driven reliably, and energy is saved because there is no need to increase the current value more than necessary.

In the present invention, the control unit 40 may count the value of the number of times ink is ejected by the inkjet head 31. In this case, when the inkjet head 31 is capable of ejecting ink droplets of multiple sizes, the counting unit 150 may count the value of the number of times ink droplets of a size that is most likely to become mist are ejected, or may count the value of the number of times ejected ink droplets are ejected for each size. When the counting unit 150 counts the value of the number of times ink droplets are ejected for each size, the control unit 40 may convert the value counted for each size into an associated value corresponding to each size.

In the present invention, the counting unit 150 of the control unit 40 may count at least one of the following values: the number of times ink is ejected by the inkjet head 31, the ejection amount, the number of printed pages, and the age of the inkjet head 31. In this case, the control unit 40 increases the current value supplied to the electromagnetic valve 65 when a related value related to the counted value exceeds a predetermined threshold value.

In the present invention, the control unit 40 may refer to only one predetermined threshold value when determining whether or not to increase the current value supplied to the electromagnetic valve 65, or multiple predetermined threshold values may be provided.

In the above embodiment, the inkjet head 31 is capable of ejecting ink droplets of three sizes from the nozzles 32. However, the inkjet head 31 may be capable of ejecting ink droplets of only one size.

In the present invention, the age value of the inkjet head 31 may be counted from immediately after the printer 1 is completed, from when the user purchases the printer 1, from when the user first turns on the printer 1, or as the total power-on time. It may also be counted by any other method.

In the first and second embodiments, the control unit 40 counts a combination of the value of the ink ejection amount and the value of the age of the inkjet head 31, or the value of the number of printed sheets of paper P and the value of the age of the inkjet head 31. However, the control unit 40 may count a combination of the value of the number of ink ejections and the value of the age of the inkjet head 31. Also, in the first and second embodiments, the control unit 40 increases the current value supplied to the electromagnetic valve 65 when both of the two counted values exceed a predetermined threshold value. However, the control unit 40 may also increase the current value supplied to the electromagnetic valve 65 when one of the two counted values exceeds a predetermined threshold value.

In the above embodiment, the ink tank 61 and the inkjet head 31 are mounted on the carriage 70, which is a so-called on-carriage type, and the electromagnetic valve 65 is disposed above the carriage 70. However, the electromagnetic valve 65 may be provided below the carriage 70. The printer 1 may also be a printer in which the ink tank 61 and the inkjet head 31 are not mounted on the carriage 70. Furthermore, the printer 1 may be a line-type printer in which ink is ejected from nozzles with the position of the inkjet head fixed.

The present invention can also be applied to a liquid ejection device having a liquid ejection head that ejects liquid other than ink. The valve may be composed of an electric ball valve or an electric butterfly valve other than the electromagnetic valve 65. In other words, any valve that can be driven electrically can be used.

1 Printer 31 Inkjet head (liquid ejection head)
32 Nozzle 61 Ink tank (liquid storage section)
62a Ink storage chamber (liquid storage chamber)
64 Atmospheric communication passage 65 Solenoid valve (valve)
70 Carriage 71 Moving mechanism 90 Table 190 Table P Paper (recording medium)

Claims (8)

a liquid ejection head having a nozzle for ejecting liquid;
a liquid storage section including a liquid storage chamber for storing liquid, an atmosphere communication passage for communicating the liquid storage chamber with the outside, and a valve for electrically opening and closing the atmosphere communication passage;
A control unit that supplies a current to drive the valve,
The control unit is
Counting at least one of the number of times the liquid is discharged by the liquid discharge head, the discharge amount, the number of printed sheets, and the age of the liquid discharge head;
A liquid ejection device comprising: a counting unit that increases a current value supplied to the valve when a related value associated with the counted value exceeds a predetermined threshold value. The liquid ejection head ejects droplets of a plurality of sizes,
The control unit is
Counting the number of times or the amount of droplets discharged of a droplet size that is most likely to become a mist among the droplets of a plurality of sizes discharged by the liquid discharge head;
2. The liquid ejection device according to claim 1, wherein when a related value associated with the counted value exceeds a predetermined threshold value, a value of the current supplied to the valve is increased. The liquid ejection head ejects droplets of a plurality of sizes,
The control unit is
Counting the number of times or the amount of droplets discharged by the liquid discharge head for each size;
Convert the counted values for each size into the associated values for each size.
The liquid ejection device according to claim 1 , wherein a current value supplied to the valve is increased when a total value of the associated values corresponding to the respective sizes exceeds a predetermined threshold value. The liquid ejection device according to any one of claims 1 to 3, characterized in that a plurality of predetermined thresholds are provided. The control unit is
counting any combination of the number of times liquid is ejected by the liquid ejection head and the age of the liquid ejection head, the amount of liquid ejected by the liquid ejection head and the age of the liquid ejection head, or the number of sheets printed by the liquid ejection head and the age of the liquid ejection head;
A liquid ejection device described in any one of claims 1 to 4, characterized in that when a value related to one or both of the two counted values exceeds a predetermined threshold value, the current value supplied to the valve is increased. The control unit is
a table showing a current value corresponding to any combination of a value of the number of times liquid is ejected by the liquid ejection head and a value of the age of the liquid ejection head, a value of a liquid ejection amount by the liquid ejection head and a value of the age of the liquid ejection head, or a value of the number of prints by the liquid ejection head and a value of the age of the liquid ejection head,
6. The liquid ejection device according to claim 5, wherein the current value supplied to the valve is increased to a current value corresponding to an associated value in the table that is associated with the two counted values. a carriage supporting the liquid ejection head and the liquid storage unit;
a moving mechanism that moves the carriage in a direction intersecting a conveying direction of the recording medium ;
Further equipped with
7. The liquid ejection apparatus according to claim 1, wherein the valve is disposed above the carriage. The liquid ejection device according to any one of claims 1 to 7, characterized in that the valve is an electromagnetic valve.

Images