JP7683387B2 - liquid discharge device - Google Patents

Description

The present invention relates to a liquid ejection device having an electrically driven valve that can selectively take either a connected state that connects an atmosphere communication passage for connecting a liquid storage chamber that is connected to a liquid ejection head with the outside, or a blocked state that blocks the atmosphere communication passage.

Patent document 1 discloses a printer (liquid ejection device) that prints by ejecting ink supplied from an ink cartridge (liquid storage section) mounted on a carriage. The ink cartridge mounted on such a printer has an ink storage section (liquid storage chamber) that stores ink, an ink supply section that supplies the ink stored in the storage section to the print head section of the printer, an air chamber into which outside air is introduced, and an air valve for introducing air from the air chamber into the ink storage section.

The atmospheric valve opens when ink in the ink storage unit is supplied to the printer and the pressure difference between the air chamber and the ink storage unit increases. Then, when air is introduced into the ink storage unit and the pressure difference between the air chamber and the ink storage unit decreases, the atmospheric valve returns to a closed state. This keeps the pressure in the ink storage unit within an appropriate pressure range, preventing poor ink supply caused by excessive negative pressure in the ink storage unit.

JP 2017-94658 A

As mentioned above, if an atmospheric valve that opens and closes depending on the pressure difference between the air chamber and the ink storage section is used as a means for adjusting the negative pressure in the ink storage chamber, the valve cannot be opened and closed at any timing that is unrelated to the pressure difference between the air chamber and the ink storage section. Therefore, it is possible to use an electrically driven valve instead of the atmospheric valve. When an electrically driven valve is used, it is necessary to control the operation of the valve taking into account its relationship with other electrically driven devices.

The object of the present invention is to provide a liquid ejection device that can control the opening and closing of an electrically driven valve while taking into account the relationship with other electrically driven devices.

The liquid ejection device according to the first 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 section having an electrically operated valve capable of selectively taking either a connected state that connects the atmosphere communication passage or a blocked state that blocks the atmosphere communication passage, a liquid flow path that connects the liquid ejection head and the liquid storage chamber so that liquid can flow through, and a control section, wherein the control section executes a valve opening/closing process that switches the valve from the blocked state to the connected state and then returns it to the blocked state, and an opening/closing feasibility determination process that determines whether or not the valve opening/closing process can be executed, and in the opening/closing feasibility determination process, when liquid is not being ejected from the nozzle, it determines that the valve opening/closing process is executable, and when liquid is being ejected from the nozzle, it determines that the valve opening/closing process is not executable, and when it determines that the valve opening/closing process is executable by the opening/closing feasibility determination process, it permits the valve opening/closing process, and when it determines that the valve opening/closing process is not executable, it does not permit the valve opening/closing process.

The liquid ejection device according to the second 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 section having an electrically driven valve capable of selectively taking either a communication state for connecting the atmosphere communication passage or a blocking state for blocking the atmosphere communication passage, a liquid flow path connecting the liquid ejection head and the liquid storage chamber so that liquid can flow, a motor, and a control section, and the control section controls a valve opening and closing process for switching the valve from the blocking state to the connecting state and then returning it to the blocking state, and a control section for controlling the motor. A drive state determination process is executed to determine whether the motor is in a first state or a second state in which the drive load is greater than that of the first state, and an opening/closing feasibility determination process is executed to determine that the valve opening/closing process is executable if the drive state determination process determines that the motor is in the first state, and to determine that the valve opening/closing process is not executable if the motor is in the second state. In the opening/closing feasibility determination process, if it is determined that the valve opening/closing process is executable, the valve opening/closing process is permitted, and if it is determined that the valve opening/closing process is not executable, the valve opening/closing process is not permitted.

If the valve opening and closing process is performed while liquid is being ejected from the nozzle, the voltage fluctuation caused by the valve opening and closing process may cause a shortage of power supplied to the liquid ejection head, which may affect the ejection of liquid from the nozzle. According to the liquid ejection device of the first invention, the valve opening and closing process is not performed while liquid is being ejected from the nozzle of the liquid ejection head, so that it is possible to avoid affecting the ejection of liquid from the nozzle. Therefore, it is possible to control the opening and closing of the valve while taking into account the relationship with the liquid ejection head.

If the valve opening and closing process is executed while the motor is driven, the valve driving load is added to the motor driving load, and there is a risk that the load may exceed the usage limit of the device. With the liquid ejection device according to the second invention, the valve opening and closing process is not executed when the motor driving load is relatively large, thereby making it possible to avoid excessive load. Therefore, it is possible to control the opening and closing of the valve while taking into account the relationship with the motor.

1 is a schematic perspective view 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 . 3A and 3B show the ink tank and the ink-jet head shown in FIG. 2, in which FIG. 3A is a front view and FIG. FIG. 4 is a plan view of the inkjet head shown in FIG. 3 . 5 is a cross-sectional view taken along line VV in FIG. 4. FIG. 2 is a block diagram showing the electrical configuration of the printer shown in FIG. 1 . 13 shows an opening/closing possibility determination table used in the opening/closing possibility determination process. 4 is a flowchart showing an example of an operation performed by the printer of FIG. 1 . 13 shows an opening/closing feasibility determination table used in the opening/closing feasibility determination process in the second embodiment of the present invention.

First Embodiment
A printer 1 according to a first embodiment of the present invention will be described below. The printer 1 is installed and used in the state shown in Fig. 1. In this embodiment, the three directions indicated by arrows in Fig. 1 are the up-down direction A1, the front-rear direction A2, and the left-right direction A3. The three directions shown in Fig. 1 are also reflected and shown in Figs. 2 to 6.

<Outline of Printer 1>
As shown in FIG. 1, the printer 1 has a housing 11 having a generally rectangular parallelepiped shape. 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 A2 from the opening 12, that is, to be detachable from the housing 11. Paper P 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). The printer 1 executes a printing operation based on printing 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 is aligned with the left-right direction A3 at the rear end. By opening the opening/closing cover 14, an ink tank 61 (described below) that is arranged inside the housing 11 is exposed, and it becomes possible to inject ink into the ink tank 61 to 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. 2, the printer 1 includes a feed unit 20, a pair of transport rollers 35, a recording unit 40, a pair of paper discharge rollers 36, an ASF (Auto Sheet Feed) motor 20M (see Fig. 6), a PF (Paper Feed) motor 30M (see Fig. 6), a CR (carriage) motor 70M (see Fig. 6), and a control unit 5 (see Fig. 6).

As shown in FIG. 2, the feeding unit 20 feeds the paper P placed on the paper feed tray 15 to the transport path 25. The transport roller pair 35 transports the paper P fed by the feeding unit 20 to the recording unit 40. The recording unit 40 has, for example, an inkjet recording system configuration, and records an image on the paper P transported by the transport roller pair 35. The paper discharge roller pair 36 discharges the paper P recorded by the recording unit 40 to the paper discharge tray 16.

<Feeding section 20>
As shown in FIG. 2, the feeding unit 20 is provided above the paper feed tray 15. The feeding unit 20 has a paper feed roller 21 and an arm 22. The paper feed roller 21 is supported on the tip of the arm 22. The arm 22 is supported rotatably on a support shaft 22a. The arm 22 is biased by a spring or the like in a direction in which the paper feed roller 21 contacts the paper feed tray 15 (in a direction in which the paper feed roller 21 rotates downward). The arm 22 is configured to be able to retract upward when the paper feed tray 15 is attached or detached. The paper feed roller 21 rotates by the power of the ASF motor 20M transmitted via a transmission mechanism (not shown). As a result, the paper P loaded in the paper feed tray 15 is fed to the transport path 25.

<Paper Feed Tray 15>
2, the paper feed tray 15 has an inclined wall portion 15a. The inclined wall portion 15a guides the paper P placed on the paper feed tray 15 to the transport path 25 when the paper P is fed by the paper feed roller 21.

<Transport path 25>
2, the transport path 25 is formed inside the housing 11 and bends upward from the rear end of the paper feed tray 15 toward the front side of the printer 1. The paper P fed from the paper feed tray 15 is guided by the transport path 25 so as to make a U-turn from below to above, and reaches the recording unit 40.

<Conveying Roller Pair 35 and Paper Discharge Roller Pair 36>
The conveying roller pair 35 has a conveying roller 35a arranged on the lower side and a pinch roller 35b arranged on the upper side. The conveying roller 35a rotates by the power of the PF motor 30M transmitted through a transmission mechanism (not shown). The pinch roller 35b rotates with the rotation of the conveying roller 35a. The conveying roller 35a and the pinch roller 35b rotate while sandwiching the paper P from the vertical direction A1, and convey the paper P to the recording unit 40.

The pair of discharge rollers 36 has a discharge roller 36a arranged on the lower side and a spur roller 36b arranged on the upper side. The discharge roller 36a rotates by the power of the PF motor 30M transmitted via a transmission mechanism (not shown). The spur roller 36b rotates in conjunction with the rotation of the discharge roller 36a. The discharge roller 36a and the spur roller 36b rotate while clamping the paper P from the vertical direction A1, and transport the paper P to the discharge tray 16.

<Recording unit 40>
2 and 3, the recording unit 40 has an inkjet head 41, an ink tank 61, a carriage 70, a moving mechanism 71, and a platen 17. The carriage 70 moves back and forth in a scanning direction (a left-right direction A3, a direction perpendicular to the transport direction of the paper P). The inkjet head 41 and the ink tank 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 tank 61 and the inkjet head 41 are mounted on the carriage 70. The ink tank 61 in this embodiment is entirely located above the inkjet head 41. However, this is not limited thereto, and a part of the ink tank 61 may be located above the upper surface of the inkjet head 41, and the remaining part may be located below the upper surface.

<Ink Tank 61>
3, the ink tank 61 has a tank body 62, a cap 63, and an electromagnetic valve 64. The tank body 62 has a substantially rectangular parallelepiped shape, and has an ink storage chamber 62a formed therein for storing ink. Black ink is stored 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 located in the center of the upper wall 62b in the left-right direction A3, 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 runs from the ink inlet 67 to the ink storage chamber 62a. The ink inlet 67 connects the ink storage chamber 62a to the outside.

The cap 63 shown in FIG. 3 is made of, for example, a flexible resin. The cap 63 can be attached and detached to the upper end of the cylinder 66 by a user operation, and closes or opens the ink inlet 67. The ink inlet 67 is normally closed by the cap 63, and is opened by removing the cap 63 from the cylinder 66 when injecting ink into the ink storage chamber 62a.

As shown in FIG. 3(b), the tank body 62 has an air communication passage 62e that penetrates the rear side wall 62d and connects the ink storage chamber 62a to the outside. The air communication passage 62e is located near the upper end of the rear side wall 62d.

As shown in FIG. 3(b), the electromagnetic valve 64 is a known two-way electromagnetic valve and has a valve portion 64a and a solenoid portion 64b. The electromagnetic valve 64 is fixed to the upper wall 62b. The valve portion 64a is disposed in the ink storage chamber 62a and has an internal flow path (not shown) that communicates with the air communication passage 62e and the ink storage chamber 62a, and a valve (not shown) that opens and closes the internal flow path. The solenoid portion 64b is disposed on the upper wall 62b and opens and closes the valve of the valve portion 64a.

The solenoid valve 64 is selectively placed in either a blocked state (i.e., the valve closes the internal passage) in which communication between the atmosphere communication passage 62e and the ink storage chamber 62a is blocked, or a connected state (i.e., the valve opens the internal passage) in which communication between the atmosphere communication passage 62e and the ink storage chamber 62a is established, by driving the solenoid section 64b under the control of the control section 5. By placing the solenoid valve 64 in the connected state, the negative pressure in the ink storage chamber 62a can be released.

As a modified example, the solenoid valve 64 may have the valve portion 64a connected outside the ink tank 61 so as to be able to communicate between the atmosphere communication passage 62e and the outside. In this way, it is possible to selectively take a communication state in which the atmosphere communication passage 62e is connected to the outside and a blocking state in which communication with the outside is blocked. The entire solenoid valve 64 may also be disposed in the ink storage chamber 62a. The solenoid valve 64 may also be fixed and installed to at least one of the front, rear, left, and right side walls other than the top wall 62b of the tank body 62, as long as the internal flow path of the valve portion 64a is connected so as to be able to communicate with the atmosphere communication passage 62e.

In addition, the tank body 62 is formed with 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 41. The outlet 62h is located in the center of the bottom wall 62g in the left-right direction A3, near the front end.

<Inkjet head 41>
Black ink is supplied to the inkjet head 41 from an ink tank 61. The inkjet head 41 ejects ink from a plurality of nozzles 42 formed on a nozzle surface 41a (see FIG. 5), which is the lower surface of the inkjet head 41. To explain in more detail, as shown in FIG. 4, the plurality of nozzles 42 form a nozzle row that is aligned in the front-rear direction A2, that is, the transport direction of the paper P. Black ink is ejected from the plurality of nozzles 42. As shown in FIGS. 4 and 5, the inkjet head 41 has a flow passage unit 43 and a piezoelectric actuator 50.

<Flow path unit 43>
As shown in Fig. 5, the flow passage unit 43 is formed by stacking four plates 43a to 43d in order from the top. A plurality of nozzles 42 are formed in the plate 43d, as shown in Figs. 4 and 5. A plurality of pressure chambers 45 are formed in the plate 43a. Further, a pressure chamber 45 is provided for each nozzle 42, and the right end portion overlaps with the nozzle 42 in the up-down direction A1.

As shown in Figures 4 and 5, the plate 43b has a circular through hole 46a formed in a portion that overlaps with the left end of each pressure chamber 45 in the vertical direction A1. The plate 43b also has a circular through hole 46b formed in a portion that overlaps with the right end of each pressure chamber 45 and the nozzle 42 in the vertical direction A1.

As shown in Figs. 4 and 5, a manifold flow path 47 is formed in the plate 43c. The manifold flow path 47 extends in the front-rear direction A2 (transport direction) and overlaps with the left portions of the multiple pressure chambers 45 in the up-down direction A1. This allows each pressure chamber 45 to communicate with the manifold flow path 47 via the through-hole 46a. Also, as shown in Fig. 4, a supply port 48 is provided at the downstream end of the manifold flow path 47 in the transport direction. The supply port 48 opens to the upper surface of the flow path unit 43 (i.e., the upper surface of the plate 43a).

As shown in FIG. 3, the inkjet head 41 is connected to the ink tank 61 via a connection member 69. The connection member 69 is formed with a communication passage 69a (the "liquid flow passage" of the present invention) that connects the outlet 62h and the supply port 48. This allows ink in the ink storage chamber 62a in the ink tank 61 to be supplied to the manifold flow passage 47 via the supply port 48.

As shown in Figures 4 and 5, the plate 43c has circular through holes 49 formed in the portions that overlap with the through holes 46b and the nozzles 42 in the up-down direction A1. This allows each nozzle 42 to communicate with the pressure chamber 45 via the through holes 46b and 49.

In the flow path unit 43, an individual flow path 44 is formed by the nozzle 42, the pressure chamber 45, through holes 46b and 49 that connect the nozzle 42 and the pressure chamber 45, and a through hole 46a that connects the pressure chamber 45 to the manifold flow path 47. A plurality of individual flow paths 44 are formed corresponding to the plurality of nozzles 42.

<Piezoelectric Actuator 50>
5, the piezoelectric actuator 50 has a vibration plate 51, a piezoelectric layer 52, a common electrode 53, and a plurality of individual electrodes 54. The vibration plate 51 is made of a piezoelectric material containing lead zirconate titanate as a main component, and is disposed on the upper surface of the flow path unit 43, covering the plurality of pressure chambers 45. Unlike the piezoelectric layer 52, the vibration plate 51 may be made of an insulating material other than a piezoelectric material.

The piezoelectric layer 52 is made of a piezoelectric material and is disposed on the upper surface of the vibration plate 51. As shown in FIG. 4, the piezoelectric layer 52 extends continuously across the multiple pressure chambers 45. As shown in FIG. 5, the common electrode 53 is disposed between the vibration plate 51 and the piezoelectric layer 52, and extends continuously across the multiple pressure chambers 45. The common electrode 53 is connected to a power source (not shown) and is held at ground potential.

As shown in FIG. 4, the multiple individual electrodes 54 correspond individually to the multiple pressure chambers 45. The individual electrodes 54 have an elliptical planar shape that is slightly smaller than the pressure chambers 45, are disposed on the upper surface of the piezoelectric layer 52, and overlap with the center of the pressure chamber 45 in the vertical direction A1. Each of the multiple individual electrodes 54 is connected to a driver IC (not shown), and the driver IC selectively applies either a ground potential or a drive potential (e.g., about 20 V).

The portions of the piezoelectric layer 52 sandwiched between the common electrode 53 and each individual electrode 54 are polarized in the vertical direction A1. In the piezoelectric actuator 50, the portions of the vibration plate 51, the piezoelectric layer 52, and the common electrode 53 that overlap each pressure chamber 45 in the vertical direction, and the portions formed by the individual electrodes 54 each serve as drive elements 55 that apply pressure to the ink in the pressure chambers 45.

Here, a method of driving the piezoelectric actuator 50 to eject ink from the nozzle 42 will be described. In the piezoelectric actuator 50, all individual electrodes 54 are held in advance at the same ground potential as the common electrode 53. When ejecting ink from a certain nozzle 42, the potential of the individual electrode 54 in the drive element 55 corresponding to that nozzle 42 is switched from the ground potential to the drive potential. Then, due to the potential difference between the individual electrode 54 and the common electrode 53, the portion of the vibration plate 51 and the piezoelectric layer 52 that overlaps with the pressure chamber 45 in the up-down direction A1 is deformed so as to be convex toward the pressure chamber 45 as a whole. This reduces the volume of the pressure chamber 45, increasing the pressure of the ink in the pressure chamber 45, and ink is ejected from the nozzle 42 that communicates with the pressure chamber 45.

<Platen 17>
The platen 17 is disposed below the inkjet head 41 and supports the paper P transported by the transport roller pair 35. The platen 17 is disposed in a portion of the reciprocating movement range of the carriage 70 through which the paper P passes. Since the width of the platen 17 is sufficiently larger than the maximum width of the paper P that can be transported, the paper P transported along the transport path 25 always passes over the platen 17.

<Movement mechanism 71>
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 disposed apart in the front-rear direction A2 and extend parallel to each other in the left-right direction A3. The carriage 70 is disposed so as to straddle the pair of guide rails 72. The carriage 70 is connected to a CR motor 70M (see Fig. 6) via the belt transmission mechanism, and when the CR motor 70M is driven, the belt transmission mechanism is driven. As a result, the carriage 70 moves in the scanning direction (left-right direction A3) along the pair of guide rails 72 together with the ink tank 61 and the inkjet head 41.

The inkjet head 41 ejects ink from the nozzles 42 under the control of the control unit 5 based on the recording data. In other words, as the carriage 70 moves back and forth in the left-right direction A3, the inkjet head 41 scans the paper P and ejects ink from the nozzles 42, thereby recording an image on the paper P transported over the platen 17.

<Control unit 5>
As shown in Fig. 6, the control unit 5 has a central processing unit (CPU) 131, an application specific integrated circuit (ASIC) 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 read only memory (ROM) 132, a random access memory (RAM) 133, and an electrically erasable programmable read-only memory (EEPROM) 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 ASF motor 20M, PF motor 30M, CR motor 70M, inkjet head 41, solenoid valve 64, etc., and controls their operation.

For example, the control unit 5 controls the ASF motor 20M, PF motor 30M, CR motor 70M, inkjet head 41, etc. based on recording data sent from an external device (e.g., a PC or a smartphone) to record an image on the paper P. The image is recorded by alternately performing a transport process in which the paper P is transported a predetermined distance in the transport direction, and a scanning process in which ink is ejected from the multiple nozzles 42 of the inkjet head 41 while moving the carriage 70 in the scanning direction.

The control unit 5 also controls the operation of the electromagnetic valve 64 and executes a valve opening/closing process that switches the electromagnetic valve 64 from a blocked state to a connected state and then returns it to the blocked state.

Furthermore, the control unit 5 executes an opening/closing feasibility determination process that determines whether or not the valve opening/closing process can be executed. Then, the control unit 5 permits the valve opening/closing process if it determines through the opening/closing feasibility determination process that the valve opening/closing process can be executed, and does not permit the valve opening/closing process if it determines that the valve opening/closing process cannot be executed.

Here, the inkjet head 41 and the electromagnetic valve 64 are both electrically driven devices. If the valve opening and closing process is performed while ink is being ejected from the nozzle 42, the voltage fluctuation caused by the valve opening and closing process may cause a shortage of power supplied to the inkjet head 41, which may affect the ejection of ink from the nozzle 42 and result in a deterioration in the quality of the formed image.

Therefore, in the opening/closing feasibility determination process, the control unit 5 determines that the valve opening/closing process can be executed when ink is not being ejected from the nozzle 42. Also, when ink is being ejected from the nozzle 42, the control unit 5 determines that the valve opening/closing process cannot be executed.

The extent of the impact on ink ejection when an ink ejection operation and a valve opening and closing operation are performed simultaneously varies depending on the model of printer 1. Therefore, the need for restrictions on the simultaneous execution of ink ejection operation and valve opening and closing operation is determined for each model of printer 1. That is, in models in which the impact on ink ejection when an ink ejection operation and a valve opening and closing operation are performed simultaneously is relatively large, restrictions are placed on the simultaneous execution of ink ejection operation and valve opening and closing operation. In addition, in models in which the impact on ink ejection when an ink ejection operation and a valve opening and closing operation are performed simultaneously is relatively small, restrictions are not placed on the simultaneous execution of ink ejection operation and valve opening and closing operation.

The EEPROM 134 stores an opening/closing feasibility determination table as shown in FIG. 7. As shown in FIG. 7, in models that have restrictions on the simultaneous execution of ink ejection operation and valve opening/closing operation, when the "ink ejection status" is "non-ejection", the "valve opening/closing process" is "enabled", and when the "ink ejection status" is "ejection", the "valve opening/closing process" is "not enabled". In models that do not have restrictions on the simultaneous execution of ink ejection operation and valve opening/closing operation, the "valve opening/closing process" is "enabled" whether the "ink ejection status" is "non-ejection" or "ejection". The control unit 5 determines whether the valve opening/closing process can be executed in the opening/closing feasibility determination process based on the opening/closing feasibility determination table in FIG. 7.

In addition, the control unit 5 functions as a measurement unit that measures the negative pressure in the ink storage chamber 62a. Specifically, the control unit 5 cumulatively counts the number of dots in an image formed by ink ejected from the nozzles 42 of the inkjet head 41 during the period in which the electromagnetic valve 64 is in a blocked state. Then, based on the counted number of dots, the control unit 5 calculates the amount of ink used during the period in which the electromagnetic valve 64 is in a blocked state, and measures the negative pressure in the ink storage chamber 62a based on this. Note that when the valve opening/closing process is executed, the cumulative count of the number of dots is reset.

The control unit 5 also executes a negative pressure determination process to determine whether the negative pressure in the ink storage chamber 62a measured based on the cumulative count of the number of dots is equal to or greater than a threshold. The negative pressure determination process includes a first determination process to determine whether the negative pressure in the ink storage chamber 62a is equal to or greater than a first threshold, and a second determination process to determine whether the negative pressure in the ink storage chamber 62a is equal to or greater than a second threshold that is higher than the first threshold.

The control unit 5 executes an opening/closing feasibility determination process if it determines in the first determination process that the negative pressure in the ink storage chamber 62a is equal to or greater than the first threshold. Then, if it determines in the opening/closing feasibility determination process that the valve opening/closing process cannot be executed, it executes a second determination process.

Furthermore, when the control unit 5 determines in the second determination process that the negative pressure in the ink storage chamber 62a is equal to or greater than the second threshold, it executes a stop process to stop image recording. In the stop process, it stops driving the PF motor 30M, the CR motor 70M, and the inkjet head 41, and stops the paper P transport process and the scanning process of moving the carriage 70 and ejecting ink from the nozzles 42. The stop process is executed after image recording on the paper P on which image recording is being performed at the time when it is determined in the second determination process that the negative pressure is equal to or greater than the second threshold is completed, and before starting image recording on the next paper P. After executing the stop process, the control unit 5 executes a valve opening and closing process.

In this embodiment, the control unit 5 has one CPU and one ASIC, but the control unit 5 may include only one ASIC, which performs all the necessary processing, or it may include multiple ASICs, which share the necessary processing.

<Operation of Printer 1>
Next, an example of the operation performed by the printer 1 will be described with reference to the flow chart shown in Fig. 8. First, the control unit 5 cumulatively counts the number of dots of an image formed by ink ejected from the nozzles 42 of the inkjet head 41 (S1). Then, based on the number of dots counted in S1, it is determined whether the negative pressure level in the ink storage chamber 62a is equal to or greater than a first threshold value (S2). If it is determined that the negative pressure level is not equal to or greater than the first threshold value (S2: NO), the process returns to S1.

On the other hand, if it is determined that the negative pressure level is equal to or higher than the first threshold (S2: YES), the control unit 5 determines whether or not to execute the valve opening/closing process based on the opening/closing feasibility determination table of FIG. 7 (S3). If it is determined that the valve opening/closing process can be executed (S3: YES), the control unit 5 permits the valve opening/closing process and proceeds to S6, which will be described later.

If it is determined that the valve opening/closing process cannot be executed (S3: NO), the control unit 5 does not permit the valve opening/closing process. Then, the control unit 5 determines whether the negative pressure level in the ink storage chamber 62a measured based on the number of dots counted in S1 is equal to or greater than a second threshold (S4). If it is determined that the negative pressure level is not equal to or greater than the second threshold (S4: NO), the process returns to S1.

On the other hand, if it is determined that the negative pressure level is equal to or greater than the second threshold (S4: YES), the control unit 5 executes a stop process to stop image recording (S5). After that, the control unit 5 executes a valve opening/closing process to switch the electromagnetic valve 64 from a blocked state to a connected state and then back to the blocked state (S6). Finally, the control unit 5 resets the cumulative dot count (S7).

The above operations are repeated while the printer 1 is powered on. Therefore, after executing the process of S7, the process returns to S1.

<Features of the First Embodiment>
As described above, in the printer 1 of the above-described embodiment, the control unit 5 executes a valve opening/closing process that switches the electromagnetic valve 64 from a blocked state to a communicating state and then returns it to the blocked state, and an opening/closing feasibility determination process that determines whether the valve opening/closing process can be executed. In the opening/closing feasibility determination process, the control unit 5 determines that the valve opening/closing process is executable when ink is not being ejected from the nozzles 42, and determines that the valve opening/closing process is not executable when ink is being ejected from the nozzles 42. The control unit 5 permits the valve opening/closing process when it has determined by the opening/closing feasibility determination process that the valve opening/closing process is executable, and does not permit the valve opening/closing process when it has determined that the valve opening/closing process is not executable.

If the valve opening and closing process is executed while ink is being ejected from the nozzle 42, the voltage fluctuation caused by the valve opening and closing process may cause a shortage of power supplied to the inkjet head 41, which may affect the ejection of ink from the nozzle 42. With the above-mentioned configuration, the valve opening and closing process is not executed while ink is being ejected from the nozzle 42 of the inkjet head 41, so that it is possible to avoid affecting the ejection of ink from the nozzle 42. Therefore, it is possible to control the opening and closing of the electromagnetic valve 64 while taking into account its relationship with the electrically driven inkjet head 41.

In addition, in the printer 1 of the above embodiment, the control unit 5 measures the negative pressure in the ink storage chamber 62a based on the cumulative count of the number of dots. The control unit 5 then executes a negative pressure determination process to determine whether the negative pressure in the ink storage chamber 62a is equal to or greater than a threshold value, and executes an open/close feasibility determination process if the negative pressure determination process determines that the negative pressure in the ink storage chamber 62a is equal to or greater than the threshold value. Therefore, when the negative pressure in the ink storage chamber 62a increases, the opening and closing of the electromagnetic valve 64 can be controlled while taking into account its relationship with the inkjet head 41.

Furthermore, in the printer 1 of the above embodiment, the negative pressure determination process includes a first determination process for determining whether the negative pressure in the ink storage chamber 62a is equal to or greater than a first threshold, and a second determination process for determining whether the negative pressure in the ink storage chamber 62a is equal to or greater than a second threshold higher than the first threshold. The control unit 5 executes an open/close feasibility determination process when it determines in the first determination process that the negative pressure in the ink storage chamber 62a is equal to or greater than the first threshold, and executes a second determination process when it determines in the open/close feasibility determination process that the valve open/close process cannot be executed. Then, when it determines in the second determination process that the negative pressure in the ink storage chamber 62a is equal to or greater than the second threshold, it executes a stop process for stopping the recording of an image, and executes a valve open/close process after executing the stop process. Therefore, the electromagnetic valve 64 can be appropriately controlled according to the magnitude of the negative pressure in the ink storage chamber 62a.

Second Embodiment
Next, a printer according to a second embodiment of the present invention will be described with reference to Fig. 9. The printer of this embodiment differs from the printer 1 of the first embodiment mainly in the contents of the open/close possibility determination process executed by the control unit 5. Hereinafter, components having the same configuration as those of the first embodiment will be given the same reference numerals and their description will be omitted as appropriate.

In this embodiment, the control unit 5 executes a drive state determination process to determine the drive state of the PF motor 30M for driving the transport roller 35a, which is the drive roller of the transport roller pair 35, and the discharge roller 36a, which is the drive roller of the discharge roller pair 36, and the CR motor 70M for driving the moving mechanism 71 that moves the carriage 70. Specifically, the control unit 5 determines whether the PF motor 30M and the CR motor 70M are in a first state or a second state that has a greater drive load than the first state. In this embodiment, the control unit 5 determines that the first state is present when the motor is not driven, and that the second state is present when the motor is driven.

Here, the PF motor 30M, the CR motor 70M, and the solenoid valve 64 are all electrically driven devices. If the valve opening and closing process is performed while the PF motor 30M and the CR motor 70M are being driven, the driving load of the solenoid valve 64 is added to the driving load of the PF motor 30M and the CR motor 70M, and there is a risk that the load will exceed the rated load, which is the usage limit of the printer 1.

The control unit 5 therefore determines in the opening/closing feasibility determination process that the valve opening/closing process can be executed when the drive state determination process determines that at least one of the PF motor 30M and the CR motor 70M is in the first state (not driven). Also, when the drive state determination process determines that both the PF motor 30M and the CR motor 70M are in the second state (driven), it determines that the valve opening/closing process cannot be executed. Then, when the control unit 5 determines in the opening/closing feasibility determination process that the valve opening/closing process can be executed, it permits the valve opening/closing process, and when it determines that the valve opening/closing process cannot be executed, it does not permit the valve opening/closing process.

The load rating of the printer 1 differs depending on the model of the printer 1. Therefore, the necessity of restricting the simultaneous execution of the drive of the PF motor 30M and the CR motor 70M and the valve opening and closing operation is determined for each model of the printer 1. That is, in models with a relatively small load rating, there is a restriction on the simultaneous execution of the drive of the PF motor 30M and the CR motor 70M and the valve opening and closing operation. In addition, in models with a relatively large load rating, there is no restriction on the simultaneous execution of the drive of the PF motor 30M and the CR motor 70M and the valve opening and closing operation.

EEPROM 134 stores an opening/closing possibility determination table as shown in FIG. 9. As shown in FIG. 9, in a model in which a restriction is set on the simultaneous execution of the driving of PF motor 30M and CR motor 70M and the valve opening/closing operation, when both the "PF motor driving status" and the "CR motor driving status" are "driving", the "valve opening/closing process" is "not possible", and when at least one of the "PF motor driving status" and the "CR motor driving status" is "not driving", the "valve opening/closing process" is "possible". In addition, in a model in which a restriction is not set on the simultaneous execution of the driving of PF motor 30M and CR motor 70M and the valve opening/closing operation, the "valve opening/closing process" is "possible" in both situations. The control unit 5 determines whether or not the valve opening/closing process can be executed in the opening/closing possibility determination process based on the opening/closing possibility determination table in FIG. 9.

<Features of the second embodiment>
As described above, in this embodiment, the control unit 5 executes a drive state determination process for determining whether the electrically driven motors (PF motor 30M and CR motor 70M) are in a first state or a second state in which the drive load is greater than that of the first state, and an opening/closing feasibility determination process for determining that the valve opening/closing process is executable if it is determined that the motor is in the first state in the drive state determination process, and determining that the valve opening/closing process is not executable if it is determined that the motor is in the second state. Then, in the opening/closing feasibility determination process, if it is determined that the valve opening/closing process is executable, the valve opening/closing process is permitted, and if it is determined that the valve opening/closing process is not executable, the valve opening/closing process is not permitted.

If the valve opening/closing process is executed while the motor is driven, the valve driving load is added to the motor driving load, and there is a risk that the load may exceed the usage limit of the device. With the above-mentioned configuration, by not executing the valve opening/closing process when the motor driving load is relatively large, it is possible to prevent the load from becoming excessive. Therefore, it is possible to control the opening and closing of the solenoid valve 64 while taking into account the relationship with the motors (PF motor 30M and CR motor 70M).

In addition, in this embodiment, in the drive state determination process, the control unit 5 determines that the motor is in the first state when it is not driven, and determines that the motor is in the second state when it is driven. Therefore, by preventing the valve opening/closing process from being executed when the motor is driven, excessive load can be avoided.

Furthermore, in this embodiment, the drive state determination process determines whether each of the PF motor 30M and the CR motor 70M is in the first state or the second state, and in the opening/closing feasibility determination process, if the drive state determination process determines that at least one of the PF motor 30M and the CR motor 70M is in the first state, it is determined that the valve opening/closing process can be executed, and if the drive state determination process determines that both the PF motor 30M and the CR motor 70M are in the second state, it is determined that the valve opening/closing process cannot be executed. Therefore, by not executing the valve opening/closing process when the drive loads of both the PF motor 30M and the CR motor 70M are large, excessive load can be avoided.

Although the embodiments of the present invention have been described above with reference to the drawings, the specific configuration should not be considered to be limited to these embodiments. The scope of the present invention is indicated by the claims rather than the description of the above embodiments, and further includes all modifications within the meaning and scope equivalent to the claims.

For example, in the second embodiment described above, the drive state determination process determines that the motor is in the first state when it is not driven, and determines that the motor is in the second state when it is driven, but this is not limited to the above. In other words, the drive state determination process may determine that the motor is in the first state when it is not driven and is not accelerating, and determine that the motor is in the second state when it is accelerating.

In the second embodiment described above, the valve opening/closing process is determined to be executable when the drive state determination process determines that at least one of the two motors, PF motor 30M and CR motor 70M, is in the first state, and the valve opening/closing process is determined to be infeasible when the drive state determination process determines that both of the two motors, PF motor 30M and CR motor 70M, are in the second state. However, this is not limited to the above. In other words, in the opening/closing process, the valve opening/closing process may be determined to be executable when the drive state determination process determines that both of the two motors, PF motor 30M and CR motor 70M, are in the first state, and the valve opening/closing process may be determined to be infeasible when the drive state determination process determines that at least one of the two motors, PF motor 30M and CR motor 70M, is in the second state. The opening/closing feasibility determination process may be performed based on only the drive state of either the PF motor 30M or the CR motor 70M, determining that the valve opening/closing process can be performed when the motor is in a first state, and determining that the valve opening/closing process cannot be performed when the motor is in a second state. Furthermore, the opening/closing feasibility determination process may be performed taking into account not only the drive states of the PF motor 30M and the CR motor 70M, but also, for example, the drive state of the ASF motor 20M.

Furthermore, in the above embodiment, the control unit 5 measures the negative pressure in the ink storage chamber 62a based on the cumulative count of the number of dots, but this is not limited to the above. In other words, the negative pressure in the ink storage chamber 62a may be measured by a pressure sensor.

In the above embodiment, the negative pressure determination process includes a first determination process for determining whether the negative pressure in the ink storage chamber 62a is equal to or greater than a first threshold, and a second determination process for determining whether the negative pressure in the ink storage chamber 62a is equal to or greater than a second threshold that is higher than the first threshold, but is not limited to this. The negative pressure determination process may be performed with respect to only one threshold.

In addition, in the above embodiment, the opening/closing feasibility determination process is executed when it is determined that the negative pressure in the ink storage chamber 62a is equal to or greater than a threshold value, but this is not limited to the above. For example, the opening/closing feasibility determination process may be executed at predetermined time intervals during continuous printing.

Furthermore, in the above embodiment, the stop process is described as being executed after image recording on the paper P on which image recording is being performed at the time when it is determined in the second determination process that the negative pressure is equal to or greater than the second threshold, and before image recording on the next paper P is started, but this is not limited to the above. For example, the stop process may be executed immediately at the time when it is determined in the second determination process that the negative pressure is equal to or greater than the second threshold.

In addition, in the above embodiment, the present invention is applied to a monochrome printer, but the present invention may also be applied to a color printer.

In addition, in the above embodiment, the ink tank 61 is provided with an ink inlet 67 that connects the ink tank 61 to the outside, but the ink tank 61 does not have to be provided with an ink inlet 67.

In addition, in the above embodiment, the ink tank 61 is provided with an electromagnetic valve 64, but this is not limited to the above. In other words, the valve provided in the ink tank 61 may be an electrically driven valve, and for example, an electric valve driven by a motor may be used instead of the electromagnetic valve 64.

Furthermore, in the above embodiment, the ink tank 61 and the inkjet head 41 are described as being on-carriage type, in which they are mounted on the carriage 70, but this is not limited to this. In other words, the present invention can also be used in a line-type inkjet head in which the inkjet head is fixed without the carriage 70.

The present invention can also be applied to a liquid ejection device having a liquid ejection head that ejects liquid other than ink. Furthermore, the ejection target is not limited to paper P, but may be, for example, cloth, a substrate, etc. It is also possible to employ an ejection energy imparting means other than the piezoelectric actuator 50. In this case, for example, a thermal type ejection energy imparting means may be employed in which a heating element heats the liquid ink in the nozzle, generating bubbles, which push the ink out of the nozzle to perform recording.

1. Printer (liquid ejection device)
5 Control unit 35 Conveying roller pair (conveying mechanism)
36 Paper discharge roller pair (transport mechanism)
41 Inkjet head (liquid ejection head)
61 Ink tank (liquid storage section)
62a Ink storage chamber (liquid storage chamber)
62e Atmospheric communication passage 64 Solenoid valve (valve)
69a Communication path (liquid flow path)
70 Carriage 71 Moving mechanism 30M CR motor 70M PF motor

Claims (11)

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 an electrically operated valve capable of selectively taking either a communication state for communicating the atmosphere communication passage or a blocking state for blocking the atmosphere communication passage;
a liquid flow path that connects the liquid ejection head and the liquid storage chamber so that liquid can flow therethrough;
A control unit,
the control unit performs a valve opening/closing process of switching the valve from the blocking state to the communicating state and then returning the valve to the blocking state;
an opening/closing possibility determination process for determining whether or not the valve opening/closing process can be executed;
in the opening/closing feasibility determination process, when liquid is not being ejected from the nozzle, it is determined that the valve opening/closing process is executable, and when liquid is being ejected from the nozzle, it is determined that the valve opening/closing process is not executable;
A liquid ejection device characterized in that the valve opening and closing process is permitted when it is determined that the valve opening and closing process can be executed by the opening and closing feasibility determination process, and the valve opening and closing process is not permitted when it is determined that the valve opening and closing process cannot be executed. 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 an electrically operated valve capable of selectively taking either a communication state for communicating the atmosphere communication passage or a blocking state for blocking the atmosphere communication passage;
a liquid flow path that connects the liquid ejection head and the liquid storage chamber so that liquid can flow therethrough;
A motor;
A control unit,
the control unit performs a valve opening/closing process of switching the valve from the blocking state to the communicating state and then returning the valve to the blocking state;
a drive state determination process for determining whether the motor is in a first state or a second state in which a drive load is larger than that in the first state;
an opening/closing feasibility determination process for determining that the valve opening/closing process is executable when it is determined that the motor is in the first state in the drive state determination process, and determining that the valve opening/closing process is not executable when it is determined that the motor is in the second state,
A liquid ejection device characterized in that, in the opening/closing feasibility determination process, the valve opening/closing process is permitted if it is determined that the valve opening/closing process can be executed, and the valve opening/closing process is not permitted if it is determined that the valve opening/closing process cannot be executed. The liquid ejection device according to claim 2, wherein, in the drive state determination process, the control unit determines that the motor is in the first state when the motor is not driven, and determines that the motor is in the second state when the motor is driven. The liquid ejection device according to claim 2, wherein, in the drive state determination process, the control unit determines that the motor is in the first state when the motor is not driven or accelerating, and determines that the motor is in the second state when the motor is accelerating. The recording medium is further provided with a transport mechanism.
5. The liquid ejection apparatus according to claim 2, wherein the motor drives the transport mechanism. a carriage supporting the liquid ejection head and the liquid storage unit;
a moving mechanism for moving the carriage,
5. The liquid ejection device according to claim 2, wherein the motor drives the movement mechanism. a conveying mechanism that conveys the recording medium in a conveying direction;
a carriage supporting the liquid ejection head and the liquid storage unit;
a moving mechanism for moving the carriage in a scanning direction intersecting the transport direction,
The motor includes two motors, one for driving the transport mechanism and the other for driving the movement mechanism,
The control unit is
In the drive state determination process, it is determined whether each of the two motors is in the first state or the second state;
A liquid ejection device as described in any one of claims 2 to 4, wherein, in the opening/closing feasibility determination process, if the drive state determination process determines that at least one of the two motors is in the first state, it is determined that the valve opening/closing process is executable, and if the drive state determination process determines that both of the two motors are in the second state, it is determined that the valve opening/closing process is not executable. The liquid storage chamber further includes a measuring unit for measuring a negative pressure in the liquid storage chamber,
the control unit further executes a negative pressure determination process for determining whether the negative pressure in the liquid storage chamber measured by the measurement unit is equal to or greater than a threshold value;
8. The liquid ejection device according to claim 1, wherein the opening/closing feasibility determination process is executed when it is determined in the negative pressure determination process that the negative pressure in the liquid storage chamber is equal to or greater than the threshold value. The liquid storage chamber further includes a measuring unit for measuring a negative pressure in the liquid storage chamber,
the control unit further executes a negative pressure determination process including a first determination process for determining whether the negative pressure in the liquid storage chamber measured by the measurement unit is equal to or greater than a first threshold value, and a second determination process for determining whether the negative pressure in the liquid storage chamber measured by the measurement unit is equal to or greater than a second threshold value that is higher than the first threshold value,
The control unit is
When it is determined in the first determination process that the negative pressure in the liquid storage chamber is equal to or greater than the first threshold value, the opening/closing feasibility determination process is executed;
When it is determined in the opening/closing feasibility determination process that the valve opening/closing process is not executable, the second determination process is executed;
when it is determined in the second determination process that the negative pressure in the liquid storage chamber is equal to or greater than the second threshold, a stop process is executed to stop driving the liquid ejection head;
The liquid ejection device according to claim 1 , wherein the valve opening/closing process is executed after the stop process is executed. The liquid storage chamber further includes a measuring unit for measuring a negative pressure in the liquid storage chamber,
the control unit further executes a negative pressure determination process including a first determination process for determining whether the negative pressure in the liquid storage chamber measured by the measurement unit is equal to or greater than a first threshold value, and a second determination process for determining whether the negative pressure in the liquid storage chamber measured by the measurement unit is equal to or greater than a second threshold value that is higher than the first threshold value,
The control unit is
When it is determined in the first determination process that the negative pressure in the liquid storage chamber is equal to or greater than the first threshold value, the opening/closing feasibility determination process is executed;
When it is determined in the opening/closing feasibility determination process that the valve opening/closing process is not executable, the second determination process is executed;
when it is determined in the second determination process that the negative pressure in the liquid storage chamber is equal to or greater than the second threshold, a stop process is executed to stop driving of the motor;
8. The liquid ejection apparatus according to claim 2, wherein the valve opening/closing process is executed after the stop process is executed. The liquid ejection device according to any one of claims 1 to 10, characterized in that the valve is an electromagnetic valve.

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