JP7600720B2 - Liquid ejection 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 describes an inkjet recording device in which ink supplied from an ink tank is stored in an ink buffer, and the ink is ejected from a print head on a carriage onto a recording medium to perform a recording operation. In this inkjet recording device, the atmosphere release electromagnetic valve that controls communication between the upper air layer in the ink buffer and the atmosphere is open during ink supply, when ink in the ink tank is supplied to the ink buffer. This allows the air in the upper part of the ink buffer to escape during ink supply, and the ink in the ink buffer is not pressurized. Also, 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.

Publication number 01-040681

In this way, the above-mentioned Patent Document 1 describes an inkjet recording device having an atmosphere venting solenoid valve, but does not describe the arrangement of a control board for controlling the atmosphere venting solenoid valve and print head, and a signal line connecting the atmosphere venting solenoid valve and print head. When the atmosphere venting solenoid valve and print head are connected to an intermediate board, and the atmosphere venting solenoid valve and print head are connected to the control board via the intermediate board, a valve signal line for sending a signal from the control board to the atmosphere venting solenoid valve and a head signal line for sending a signal from the control board to the print head are connected to connect the control board to the intermediate board.

For example, if the atmosphere release solenoid valve is located above the print head and the relay board is installed crossing the horizontal plane (e.g., vertically), and the connection position of the valve signal line to the relay board is located below the connection position of the head signal line to the relay board, if the valve wiring connected to the valve signal line is formed in the relay board toward the top so as to approach the atmosphere release solenoid valve, and the head wiring connected to the head signal line is formed in the relay board toward the bottom so as to approach the print head, the two wirings are likely to cross, which makes it easier for noise interference to occur. On the other hand, if the valve wiring and the head wiring are arranged in the relay board so as not to cross each other, at least one of the distance from the connection position of the wiring connecting the relay board and the atmosphere release solenoid valve to the relay board to the atmosphere release solenoid valve and the distance from the connection position of the wiring connecting the relay board and the print head to the relay board to the print head will be longer, and the wiring length corresponding to the longer distance will also be longer.

In addition, when the air release solenoid valve is arranged upstream of the print head in the transport direction of the recording medium, and the relay board is installed so as to cross (for example, horizontally) a vertical plane facing the transport direction, if the connection position of the valve signal line to the relay board is arranged downstream of the connection position of the head signal line to the relay board in the transport direction, if the valve wiring connected to the valve signal line is formed in the relay board toward the upstream of the transport direction so as to approach the air release solenoid valve, and the head wiring connected to the head signal line is formed in the downstream of the transport direction so as to approach the print head, the two wirings are likely to cross, which makes it easier for noise interference to occur. On the other hand, if the valve wiring and the head wiring are arranged in the relay board so as not to cross each other, at least one of the distance from the connection position of the wiring connecting the relay board and the air release solenoid valve to the relay board to the air release solenoid valve and the distance from the connection position of the wiring connecting the relay board and the print head to the relay board to the print head will be longer, and the wiring length corresponding to the longer distance will also be longer.

In this way, depending on the relationship between the connection position of the valve signal line to the relay board, the connection position of the head signal line to the relay board, and the arrangement positions of the atmosphere venting electromagnetic valve and the print head, at least one of the problems of noise interference occurring within the relay board and at least one of the wiring connecting the relay board to the atmosphere venting electromagnetic valve and the wiring connecting the relay board to the print head becoming longer may occur.

The object of the present invention is to provide a liquid ejection device that can suppress noise interference within the relay board and prevent the wiring connecting the relay board to the liquid ejection head and the wiring connecting the relay board to the valve from becoming too long.

The liquid ejection device of the present invention includes 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 control unit having a control board and controlling the liquid ejection head and the valve, a relay board installed crossing a horizontal plane, a head signal line connected to connect the control board and the relay board and for transmitting a signal from the control board to the liquid ejection head, and a valve signal line connected to connect the control board and the relay board and for transmitting a signal from the control board to the valve. The valve is disposed above the liquid ejection head, and the connection position of the valve signal line to the relay board is above the connection position of the head signal line to the relay board.

According to the liquid ejection device of the present invention, the connection position of the valve signal line to the relay board is closer to the valve, and the connection position of the head signal line to the relay board is closer to the liquid ejection head. This eliminates the need to cross the valve wiring connected to the valve signal line and the head wiring connected to the head signal line within the relay board, making it possible to suppress noise interference. It also makes it possible to suppress the lengthening of the wiring connecting from the relay board to the liquid ejection head and the wiring connecting from the relay board to the valve.

1 is a schematic perspective view of a printer according to an 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 . 6 is a cross-sectional view taken along the line VI-VI shown in FIG. 4. 1 is a schematic diagram showing the placement of a control board, a relay board, and an FPC connecting the two boards. FIG. 2 is a block diagram showing the electrical configuration of the printer shown in FIG. 1 . 4 is a flowchart showing a recording operation of the printer. 6 is a flowchart showing the operation of the printer when the liquid level sensor detects that the liquid level is empty. FIG. 1A shows a side view of an ink tank and an inkjet head of a printer according to a first modified example, and FIG. 1B is a schematic diagram showing the installation status of a control board, a relay board, and an FPC connecting these two boards of the printer according to the first modified example. FIG. 1A shows a side view of an ink tank and an inkjet head of a printer according to a second modified example, and FIG. 1B is a schematic diagram showing the installation status of a control board, a relay board, and an FPC connecting these two boards of the printer according to the second modified example.

The printer 1 according to one 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 in FIG. 2 to FIG. 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 constitutes its 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) 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. 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. 7), an LF (Line Feed) motor 35M (see Fig. 7), a liquid level sensor 6 (see Fig. 7), and a control unit 5 (see Fig. 7).

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 axially supported at the tip of the arm 22. The arm 22 is rotatably supported on a support shaft 22a, and is biased by a spring or the like to rotate the paper feed roller 21 downward so that the paper feed roller 21 comes into contact with the paper feed tray 15. The arm 22 is also configured to be able to retract upward when the paper feed tray 15 is attached or detached. The paper feed roller 21 is rotated by the power of the ASF motor 20M transmitted via a transmission mechanism (not shown), and 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 pair of conveying rollers 35 includes a conveying roller 35a disposed on the lower side and a pinch roller 35b disposed on the upper side. The conveying roller 35a rotates by the power of the LF motor 35M transmitted through a transmission mechanism (not shown). The pinch roller 35b rotates together with the rotation of the conveying roller 35a. The conveying roller 35a and the pinch roller 35b cooperate to pinch 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 LF motor 35M transmitted via a transmission mechanism (not shown). The spur roller 36b rotates with the rotation of the discharge roller 36a. The discharge roller 36a and the spur roller 36b cooperate to clamp 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 relay board 80, 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>
As shown in Fig. 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. The tank body 62 is mainly made of a light-transmitting material (e.g., a 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 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 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 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 removed from the cylinder 66 and opened when ink is to be injected into the ink storage chamber 62a.

As shown in FIG. 3(b), the tank body 62 has an air communication port 62e that penetrates the rear side wall 62d and connects the ink storage chamber 62a to the outside. The air communication port 62e is located near the upper end of the rear side wall 62d. Also, as shown in FIG. 3, the tank body 62 has an upper index 62f1 and a lower index 62f2 formed on its front side wall 62f. The air communication port 62e only needs to be located above the upper index 62f1, and may be formed in the upper wall 62b, for example.

3, the upper indicator 62f1 has a linear shape extending left and right near the upper end on the outer surface of the front side wall 62f. The upper indicator 62f1 is disposed below the air communication port 62e in the vertical direction A1, as shown in FIG. 3(b). The upper indicator 62f1 is an example of an indicator that indicates the liquid level of the maximum amount of ink that can be stored in the ink storage chamber 62a. The lower indicator 62f2 has a linear shape extending left and right near the lower end on the outer surface of the front side wall 62f. The lower indicator 62f2 is an indicator that indicates the liquid level at which ink needs to be refilled, i.e., injected into the ink storage chamber 62a. The upper indicator 62f1 and the lower indicator 62f2 can also be realized by unevenness formed on the outer surface of the front side wall 62f, or by coloring with paint or the like.

As shown in FIG. 3B, the solenoid valve 64 is a known two-way solenoid valve and has a valve portion 64a and a solenoid portion 64b. The solenoid valve 64 is fixed to the upper wall 62b so as to be positioned above the upper indicator 62f1. 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 port 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 controlled by the control unit 5, and when the solenoid unit 64b is driven, the valve unit 64a selectively takes a communication state in which the atmosphere communication port 62e communicates with the ink storage chamber 62a (i.e., the valve opens the internal passage) and a blocking state in which the atmosphere communication port 62e blocks communication with the ink storage chamber 62a (i.e., the valve closes the internal passage).

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 air communication port 62e and the outside. In this way, it is possible to selectively take a communication state in which the air communication port 62e is connected to the outside and a blocking state in which it is blocked from communication with the outside. 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 on 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 air communication port 62e.

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

As shown in FIG. 3(b), a protrusion 62i that protrudes rearward is formed on the rear side wall 62d of the tank body 62. The protrusion 62i is made of a light-transmitting material and has a generally rectangular parallelepiped shape. The protrusion 62i extends in the up-down direction A1 from a position below the lower indicator 62f2 to a position above it. The left-right dimension of the protrusion 62i is smaller than the left-right dimension of the ink storage chamber 62a. The protrusion 62i defines an internal space that communicates with the ink storage chamber 62a.

<Liquid volume sensor 6>
The liquid level sensor 6 is a transmission type optical sensor, and has a light emitting element and a light receiving element that is disposed at a position sandwiching the protrusion 62i between the light emitting element and the light emitting element and receives light from the light emitting element. The light emitting element irradiates parallel light in the left-right direction A3 toward a portion of the protrusion 62i at approximately the same vertical position as the lower index 62f2. The liquid level sensor 6 outputs a signal indicating a level according to the amount of light received by the light receiving element to the control unit 5. That is, the liquid level sensor 6 outputs a different signal to the control unit 5 when the ink level of the ink storage chamber 62a is below the lower index 62f2 (i.e., when the ink level of the ink tank 61 is empty) and when it is not. In this way, the liquid level sensor 6 can detect whether the ink level of the ink tank 61 is empty by detecting the ink level.

<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, which is the lower surface of the inkjet head 41. More specifically, the 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 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 10 in the vertical direction A1.

As shown in Figures 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-hand 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. In addition, as shown in Figure 4, a supply port 48 is provided at the downstream end of the manifold flow path 47 in the transport direction.

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 (liquid flow passage) 69a that connects the outlet 62h and the supply port 48. This allows ink in the ink storage chamber 62a of 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>
4 and 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, and extends continuously across the multiple pressure chambers 45. The common electrode 53 is disposed between the vibration plate 51 and the piezoelectric layer 52 as shown in FIG. 5, and extends continuously across the multiple pressure chambers 45. The common electrode 53 is connected to a power supply circuit (not shown) via wiring members (FPC 92, COF 92) described below, and is held at ground potential.

As shown in FIG. 4, the individual electrodes 54 correspond to the pressure chambers 45 individually. The individual electrodes 54 have an elliptical planar shape that is slightly smaller than the pressure chambers 45, are arranged on the upper surface of the piezoelectric layer 52, and overlap the center of the pressure chamber 45 in the vertical direction a1. The right end of the individual electrode 54 extends to the right to a position where it does not overlap the pressure chamber 45 in the vertical direction A1, and its tip serves as a connection terminal 54a. The connection terminal 54a is connected to a COF 91 described later, and the individual electrodes 54 are connected to a driver IC 59 (see FIG. 7) mounted on the COF (Chip On Film) 91. The driver IC 59 selectively applies either a ground potential or a predetermined drive potential (for example, about 20 V) to each of the individual electrodes 54 individually.

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 structured as described above, the portions of the vibration plate 51, piezoelectric layer 52, and 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 a driving element 55 that applies pressure to the ink in the pressure chamber 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.

<Moving 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 carriage motor 70M (see FIG. 7) via the belt transmission mechanism, and when the carriage 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, and moves the inkjet head 41 between a maintenance position facing a maintenance cap (not shown) and a non-maintenance position not facing the maintenance cap.

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, the inkjet head 41 scans the paper P as the carriage 70 moves back and forth in the left-right direction A3, and ejects ink from the nozzles 42 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 51 in the scanning direction from the count value of the light-transmitting section of the linear encoder detected by the position detection sensor while the carriage 70 is moving, and the rotation drive of the carriage motor 70M is controlled.

<Relay Board 80>
As shown in FIG. 6, the relay board 80 is connected to the control board 7 of the control unit 5 via an FPC (Flexible Printed Circuits: flexible flat cable) 8. The relay board 80 is supported by the carriage 70 and is disposed behind the ink tank 61 in a state of standing along the up-down direction A1 as shown in FIG. 3B. That is, the relay board 80 is disposed upstream of the inkjet head 41 in the transport direction and intersects with the horizontal plane. As shown in FIG. 6, the relay board 80 has a board body 81 having a rectangular planar shape, four connection parts 82 to 85, a plurality of head wirings 86, a valve wiring 88, and a sensor wiring 89. These four connection parts 82 to 85, the plurality of head wirings 86, the valve wiring 88, and the sensor wiring 89 are formed on the surface of the board body 81.

As shown in FIG. 6, the connection part 82 is formed at the right end of the substrate body 81, extending in the vertical direction A1. One end of the FPC 8 is connected to the connection part 82 in a standing state in the vertical direction A1. The connection part 83 is formed at the center of the lower end of the substrate body 81, extending in the horizontal direction A3. As shown in FIG. 3(b), the connection part 83 is connected to an FPC 92 connected to a COF 91 connected to a piezoelectric actuator 50 of the inkjet head 41. The COF 91 has the driver IC 59 mounted thereon.

As shown in FIG. 6, the connection part 84 is disposed near the center of the upper end of the substrate body 81. As shown in FIG. 3(b), a wiring 93 connected to the solenoid valve 64 is connected to the connection part 84. As shown in FIG. 6, the connection part 85 is disposed in the lower part of the left end of the substrate body 81. As shown in FIG. 3(b), a wiring 94 connected to the liquid level sensor 6 is connected to the connection part 85.

As shown in FIG. 6, the multiple head wirings 86 are formed to connect the connection parts 82 and 83. The valve wiring 88 is formed to connect the connection parts 82 and 84. The sensor wiring 89 is formed to connect the connection parts 82 and 85. The multiple head wirings 86 are arranged below the sensor wiring 89 at the connection part 82. The valve wiring 88 is arranged above the sensor wiring 89 at the connection part 82.

<FPC8>
As shown in FIG. 6, one end of the FPC 8 is connected to the connection portion 82, and the other end is connected to the connection portion 7a of the control board 7. The FPC 8 has a plurality of head signal lines 8a, a ground line 8g, a sensor signal line 8c, and a valve signal line 8b. The head signal lines 8a are lines for transmitting signals from the control board 7 to the inkjet head 41. The ground line 8g is a line for holding the common electrode 53 of the inkjet head 4 at a ground potential. The sensor signal line 8c is a line for transmitting signals from the liquid volume sensor 6 to the control board 7. The valve signal line 8b is a line for transmitting signals from the control board 7 to the electromagnetic valve 64. The head signal lines 8a, the ground line 8g, the sensor signal line 8c, and the valve signal line 8b are arranged in this order from bottom to top. In other words, the connection positions of the multiple head signal lines 8a to the relay board 80 are disposed below the connection positions of the sensor signal line 8c and the valve signal line 8b to the relay board 80. In addition, the ground line 8g is disposed between the head signal line 8a and the valve signal line 8b.

<Control unit 5>
As shown in FIG. 7, the control unit 5 includes a central processing unit (CPU) 131, an application specific integrated circuit (ASIC) 135, a memory 140, and a control board 7 on which these are mounted. 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. At least one of the CPU 131 and the memory 140 may not be mounted on the control board 7 and may be provided separately.

The ASIC 135 outputs control signals to the ASF motor 20M, LF motor 35M, carriage motor 70M, solenoid valve 64, inkjet head 41, etc., and controls their operation. For example, the control unit 5 controls the inkjet head 41, ASF motor 20M, LF motor 35M, carriage motor 70M, etc., based on recording data sent from an external device (e.g., a PC or smartphone), alternately performs a transport process and a recording process, and records an image, etc., on the paper P. The ASIC 135 also receives a signal from the liquid level sensor 6.

The conveying process is a process in which the conveying roller pair 35 and the paper discharge roller pair 36 convey the paper P by a predetermined line feed amount. The control unit 5 controls the LF motor 35M to cause the conveying roller pair 35 and the paper discharge roller pair 36 to execute the conveying process. The recording process is a process in which the carriage 70 is moved along the left-right direction A3 while controlling the power supply to the drive element 55 to eject ink droplets from the nozzle 42. The control unit 5 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 5 executes one pass in which ink droplets are ejected from the nozzle 42 while moving the carriage 70 rightward or leftward. As a result, one pass of image recording is executed on the paper P. The control unit 5 alternately executes the conveying process and the recording process, thereby making it possible to record an image in the entire area of the paper P where an image can be recorded. In other words, the control unit 5 records an image on one sheet of paper P in multiple passes.

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.

The memory 140 stores an ink count value (liquid count value), a reference value, and an ink threshold value (liquid threshold value). The ink count value is a value that is updated according to the amount of ink ejected from the inkjet head 41, and is stored in the RAM 133 or the EEPROM 134. The ink count value is calculated based on the recording data, which is data of the image to be recorded on the paper P.

More specifically, the control unit 5 refers to the recording data transmitted from an external device (e.g., a PC or a smartphone). The recording data is transmitted sequentially from the external device. The control unit 5 estimates the amount of ink to be ejected in the next recording process based on the recording data, and determines the ink count value corresponding to that amount of ink. In other words, the control unit 5 determines the number of times ink droplets are ejected for each dot in the area to be ejected in the next recording process based on the recording data. This allows the number of times that all dots in the area are ejected to be calculated by adding up the number of times each dot is ejected. The calculated number of times that all dots in the area are ejected is the ink count value corresponding to the amount of ink to be ejected in the next recording process.

As described below, the ink count value is updated by being accumulated based on the recording data. The ink count value is also reset to an initial value at a predetermined timing (timing for ink refill) under the control of the control unit 5. The initial value is a preset value that is an initial value of the ink count value and is stored in the ROM 132 or the EEPROM 134. In this embodiment, the initial value is zero. Note that in this embodiment, the ink count value is counted up from an initial value of zero, but this is not limited to this. For example, the ink count value may be counted down from an initial value other than zero.

The ink threshold is a value that is compared with the consumption amount of ink stored in the ink storage chamber 62a, and is a value for determining the timing of opening the electromagnetic valve 64. In detail, the ink threshold is a value that is preset so that the difference between the ink count value and the reference value reaches the ink threshold before the ink meniscus formed in the nozzle 42 is damaged due to the increase in negative pressure in the ink storage chamber 62a. The ink threshold is a value that is determined by design for the ink meniscus withstand pressure, and is a value that indicates less than the withstand pressure value. In other words, when the difference does not reach the ink threshold, the negative pressure in the ink storage chamber 62a is not so large, and the ink meniscus formed in the nozzle 42 is not damaged. On the other hand, when the difference reaches the ink threshold, the ink meniscus formed in the nozzle 42 is easily damaged due to the increase in negative pressure. The ink threshold is also determined by the ratio of the volume of the ink space to the volume of the air space when the maximum amount of ink is stored in the ink storage chamber 62a. In this embodiment, the ink threshold value is stored in ROM 132 or EEPROM 134.

The recording operation of the printer 1 will now be described with reference to FIG. 8. In the printer 1, the inkjet head 41 is in the maintenance position during standby (when no recording operation is being performed). At this time, the solenoid valve 64 is in a blocking state that blocks communication with the atmosphere communication port 62e. This prevents the ink in the ink storage chamber 62a from evaporating.

A recording command is sent to the control unit 5 from the operation unit 13 of the printer 1 or an external device. The recording command includes a command to start a recording operation, information about the size of the paper P, and recording data to be recorded as an image on the paper P.

If the control unit 5 has not received a recording command in S1 (NO), it waits by repeating S1, and if it has received a recording command (Yes), it proceeds to S2.

In S2, the control unit 5 drives the ASF 20M to feed the paper P from the paper feed tray 15. In S2, the control unit 5 also drives the LF motor 35M to transport the paper P and perform head alignment when the leading edge of the paper P reaches the transport roller pair 35. In head alignment, the control unit 5 stops the paper P at the image recording start position. The image recording start position is the position where the leading edge (downstream end) of the image recording area on the paper P in the transport direction faces the nozzle 42 that is located furthest downstream in the transport direction among the multiple nozzles 42.

In addition, in S2, the control unit 5 drives the carriage motor 70M to move the carriage 70 (inkjet head 41) from the maintenance position to the start position. The start position is the movement start position of the carriage 70 when the recording process (S7) is executed, and is determined based on the recording data. In S2, the operation from feeding the paper P to positioning the head and the movement operation of the carriage 70 are executed in parallel.

Next, in S3, the control unit 5 refers to the recording data and determines an ink count value that corresponds to the amount of ink to be ejected in the next pass to be executed, that is, in the next recording process (S7). The control unit 5 then adds the determined ink count value to the ink count value currently stored in the memory 140, and stores the result of the addition in the memory 140 as a new ink count value. This updates the ink count value.

Next, in S4, the control unit 5 determines whether the difference between the ink count value and the reference value has reached the ink threshold value (determination process). Note that the reference value is the ink count value stored in memory 140 by the control unit 5 at the time of the previous cutoff process in which the solenoid valve 64 changes from a connected state to a cutoff state, and stored as the reference value in memory 140. Then, as the recording process in S7 described below is repeatedly executed and the ink count value is updated, the difference between the ink count value and the reference value may reach the ink threshold value. In this case (YES), proceed to S5. On the other hand, if the difference has not reached the ink threshold value (NO), proceed to S7.

Next, the control unit 5 executes a communication process in S5. That is, the control unit 5 drives the electromagnetic valve 64 to change from a blocked state to a connected state. This causes the atmosphere communication port 62e to communicate, and the ink storage chamber 62a to be open to the atmosphere. Therefore, the negative pressure in the ink storage chamber 62a decreases (the pressure is in equilibrium with the atmospheric pressure). As a result, damage to the ink meniscus formed in the nozzle 42 is suppressed, and it is possible to suppress air from entering the nozzle 42 and ink from leaking from the nozzle 42.

Next, the control unit 5 executes a cut-off process in S6. That is, the control unit 5 drives the electromagnetic valve 64 to change from a connected state to a cut-off state. This cuts off communication with the atmosphere communication port 62e, and closes the ink storage chamber 62a to the atmosphere. At this time, the control unit 5 stores the ink count value currently stored in the memory 140 in the memory 140 as a reference value (storage process).

Next, in S7, the control unit 5 executes the recording process. That is, the control unit 5 executes one pass to eject ink droplets from the nozzles 42 while moving the carriage 70 from the start position.

Next, in S8, the control unit 5 determines whether image recording on the paper P has been completed based on the information about the size of the paper P and the recording data included in the recording command. If image recording on the paper P has not been completed (NO), the process proceeds to S9, where a conveying process is performed. If image recording on the paper P has been completed (YES), the process proceeds to S10.

Next, in S9, the control unit 5 drives the LF motor 35M to cause the transport roller pair 35 and the paper discharge roller pair 36 to transport the paper P a predetermined line feed amount. After this, the process returns to S3, and the control unit 5 determines an ink count value corresponding to the amount of ink to be ejected in the next recording process (S7), and adds the determined ink count value to the ink count value up to that point. Then, the processes of steps S4 to S8 are executed again. Note that the update of the ink count value in S3 may be executed in parallel with the transport process.

Next, in S10, the control unit 5 drives the LF motor 35M to cause the conveying roller pair 35 and the paper discharge roller pair 36 to convey the paper P and discharge it onto the paper discharge tray 16.

Next, in S11, the control unit 5 determines whether the image data included in the recording command contains image data that has not been recorded on the paper P, i.e., whether there is image recording for the next page. If there is image recording for the next page (YES), the process returns to S2. On the other hand, if there is no image recording for the next page (NO), the control unit 5 ends the series of recording operations.

Next, the operation of the printer 1 when the liquid level sensor 6 detects that the ink tank is empty will be described below with reference to FIG. 9. In the printer 1, the amount of ink in the ink tank 61 decreases as ink evaporates or is discharged from the nozzles 42 during recording operations. At this time, the solenoid valve 64 is in a blocked state in which communication with the atmosphere communication port 62e is blocked.

In S101, the control unit 5 determines whether or not a signal indicating that the ink level is empty is being output from the liquid level sensor 6. If a signal indicating empty is not being output (NO), S101 is repeatedly executed. On the other hand, if the ink level in the ink storage chamber 62a is below the lower indicator 62f2 due to ink evaporation or ink discharge from the nozzle 42, and a signal indicating empty is being output from the liquid level sensor 6 (YES), the process proceeds to S102.

In S102, the control unit 5 executes a notification process. That is, the control unit 5 displays a message on the liquid crystal display of the operation unit 13 indicating that the ink in the ink tank 61 is empty, to notify the user.

Next, the control unit 5 executes a communication process in S103. That is, the control unit 5 drives the electromagnetic valve 64 to put it into a communication state, as in S5 described above. As a result, the atmosphere communication port 62e is communicated, and the ink storage chamber 62a is opened to the atmosphere. After this, the user opens the opening/closing cover 14 of the housing 11, removes the cap 63, and opens the ink inlet 67. Then, an ink bottle (not shown) is inserted into the ink inlet 67 to inject black ink into the ink storage chamber 62a. At this time, the electromagnetic valve 64 is in a communication state, and the ink storage chamber 62a is open to the atmosphere, so that it is possible to prevent the internal pressure of the ink storage chamber 62a from increasing when the ink is injected. Therefore, damage to the ink meniscus formed in the nozzle 42 is suppressed, and ink is less likely to leak from the nozzle 42.

Next, in S104, the control unit 5 determines whether or not a signal indicating that the ink level is empty is being output from the liquid level sensor 6. If a signal indicating empty is being output (YES), the control unit 5 repeatedly waits for S104. On the other hand, if ink injection into the ink tank 61 is complete and a signal indicating empty is not being output from the liquid level sensor 6 (NO), the control unit 5 proceeds to S105.

Next, the control unit 5 executes a cut-off process in S105. That is, the control unit 5 drives the electromagnetic valve 64 to change from a connected state to a cut-off state, similar to S6 described above. At this time, the control unit 5 resets the ink count value currently stored in the memory 140 to the initial value, and stores this ink count value in the memory 140 as a reference value (storage process). This is how the flow ends.

As described above, according to the printer 1 of this embodiment, the connection positions of the multiple head signal lines 8a of the FPC 8 to the relay board 80 are arranged lower than the connection positions of the sensor signal line 8c and the valve signal line 8b to the relay board 80. Therefore, the connection position of the valve signal line 8b to the relay board 80 is closer to the electromagnetic valve 64, and the connection position of the head signal line 8a to the relay board 80 is closer to the inkjet head 41. Therefore, it is no longer necessary to cross the valve wiring 88 connected to the valve signal line 8b and the head wiring 86 connected to the head signal line 8a within the relay board 80, making it possible to suppress noise interference. In addition, it is possible to suppress the lengthening of the wiring members (COF 91 and FPC 92) connecting from the relay board 80 to the piezoelectric actuator 50 of the inkjet head 41 and the wiring 93 connecting from the relay board 80 to the electromagnetic valve 64.

In addition, because the relay board 80 is installed standing upright along the vertical direction A1, the connection position of the valve signal line 8b to the relay board 80 is closer to the electromagnetic valve 64, and the connection position of the head signal line 8a to the relay board 80 is closer to the inkjet head 41. This makes it possible to further prevent the wiring members (COF 91 and FPC 92) and the wiring 93 from becoming longer.

The relay board 80 is disposed upstream of the inkjet head 41 in the transport direction. The electromagnetic valve 64 is disposed upstream of the inkjet head 41 in the transport direction. This makes it possible to prevent the wiring 93 from becoming too long.

When it is determined in S4 that the difference has reached the ink threshold value, the control unit 5 executes a communication process in S5. This makes it possible to prevent the ink meniscus formed in the nozzle 42 from being damaged.

In the above embodiment, whether the negative pressure in the ink storage chamber 62a is within the allowable range is determined based on whether the difference between the ink count value and the reference value reaches the ink threshold value. However, as shown by the two-dot chain line in FIG. 3B, a pressure sensor 400 may be provided in the ink tank 61, and the pressure sensor 400 may detect the pressure in the ink storage chamber 62a and output a signal corresponding to the pressure to the control unit 5. In this modified example, instead of the determination process of S4, the control unit 5 may execute a determination process to determine whether the pressure detected by the pressure sensor 400 has reached a predetermined value. The predetermined value may be a value less than the withstand pressure value of the ink meniscus formed in the nozzle 42. Then, in the determination process, if the pressure has reached the predetermined value, a communication process similar to S5 may be executed, and then a blocking process similar to S6 may be executed. In this modified example, as in the above embodiment, it is possible to prevent the ink meniscus of the nozzle 42 from being damaged. In addition, since the pressure sensor 400 detects the pressure in the ink storage chamber 62a, it is possible to detect the pressure with high accuracy.

As another modified example, the pressure in the ink storage chamber 62a may be detected using a sensor other than a pressure sensor, for example at least one of a liquid volume increase/decrease sensor that detects an increase/decrease in the liquid volume in the ink storage chamber 62a, a temperature sensor, and a humidity sensor. The liquid volume increase/decrease sensor may detect the pressure in the ink storage chamber 62a by detecting a predetermined decrease or increase in the ink volume. A temperature sensor or humidity sensor may also be used to detect the pressure in the ink storage chamber 62a based on changes in the environmental temperature or humidity. A combination of these sensors may also be used to accurately detect the pressure in the ink storage chamber 62a. Then, by performing a process similar to that when the pressure sensor 400 described above is used, the same effect as in the modified example described above can be obtained.

The inkjet head 41 and ink tank 61 are supported by the carriage 70, making the printer 1 an on-carriage type.

Since the solenoid valve 64 is a valve that selectively switches between a connected state that connects the air communication port 62e and a blocked state that blocks communication, the manufacturing cost of the printer 1 is relatively low. As a variant, the valve may be an electric ball valve or an electric butterfly valve. In other words, it is sufficient that the valve can be electrically driven.

The head signal line 8a and the valve signal line 8b constitute multiple wirings formed on one FPC 8. As a result, the head signal line 8a and the valve signal line 8b are formed on one FPC 8, making it easier to arrange these signal lines 8a, 8b than if the head signal line 8a and the valve signal line 8b were formed as separate wiring members, and also preventing the head signal line 8a and the valve signal line 8b from crossing.

A ground line 8g is arranged between the head signal line 8a and the valve signal line 8b on the FPC 8. This makes the separation distance between the head signal line 8a and the valve signal line 8b relatively large, making it possible to suppress crosstalk.

The ink tank 61 has an ink inlet 67, which makes it possible to inject ink into the ink storage chamber 62a through the ink inlet 67.

As a first modified example, as shown in FIG. 10, the relay board 280 may be installed horizontally. Note that the same components as those in the above embodiment are indicated by the same reference numerals and will not be described. The relay board 280 in this modified example is also connected to the control board 7 of the control unit 5 via the FPC 8. The relay board 280 is also located above the ink tank 61. In other words, the relay board 280 is installed so as to intersect with a vertical plane facing the transport direction (front-rear direction A2). The relay board 280 has a board body 281 having a rectangular planar shape, four connection parts 282 to 285, a plurality of head wirings 286, a valve wiring 288, and a sensor wiring 289. These four connection parts 282 to 285, the plurality of head wirings 286, the valve wiring 288, and the sensor wiring 289 are formed on the surface of the board body 281.

As shown in FIG. 10(b), the connection part 282 is formed at the right end of the substrate body 281, extending along the front-rear direction A2. One end of the FPC 8 arranged along the horizontal plane is connected to the connection part 282. The connection part 283 is formed at the left end of the substrate body 281, extending along the front-rear direction A2. The connection part 283 is connected to an FPC 92 connected to a COF 91 connected to a piezoelectric actuator 50 of the inkjet head 41.

As shown in FIG. 10, the connection part 284 is disposed near the center of the rear end part of the substrate body 281. A wiring 93 connected to the solenoid valve 64 is connected to the connection part 284. The connection part 285 is disposed near the rear end part of the substrate body 281, between the connection parts 283 and 284 in the left-right direction A3. A wiring 94 connected to the liquid level sensor 6 is connected to the connection part 285.

As shown in FIG. 10(b), the multiple head wirings 286 are formed to extend in the left-right direction A3 so as to connect the connection portion 282 and the connection portion 283. The valve wiring 288 is formed so as to connect the connection portion 282 and the connection portion 284. The sensor wiring 289 is formed so as to connect the connection portion 282 and the connection portion 285. The multiple head wirings 286 are arranged in front of the sensor wiring 289 (downstream in the transport direction) at the connection portion 282. The valve wiring 288 is arranged behind the sensor wiring 289 (upstream in the transport direction) at the connection portion 282.

According to such a relay board 280, the connection positions of the multiple head signal lines 8a of the FPC 8 to the relay board 280 are arranged forward (downstream in the transport direction) of the connection positions of the sensor signal line 8c and the valve signal line 8b to the relay board 280. The electromagnetic valve 64 is arranged behind the inkjet head 41, that is, upstream in the transport direction. Therefore, in the transport direction, the connection position of the valve signal line 8b to the relay board 280 is closer to the electromagnetic valve 64, and the connection position of the head signal line 8a to the relay board 280 is closer to the inkjet head 41. Therefore, it is no longer necessary to cross the valve wiring 288 connected to the valve signal line 8b and the head wiring 286 connected to the head signal line 8a in the relay board 280, making it possible to suppress noise interference. It is also possible to prevent the wiring members (COF 91 and FPC 92) that connect from the relay substrate 280 to the piezoelectric actuator 50 of the inkjet head 41, and the wiring 93 that connects from the relay substrate 280 to the electromagnetic valve 64, from becoming too long.

In addition, because the relay board 280 is installed horizontally (front-back direction A2 and left-right direction A3), the connection position of the valve signal line 8b to the relay board 280 is closer to the electromagnetic valve 64, and the connection position of the head signal line 8a to the relay board 280 is closer to the inkjet head 41. This makes it possible to further prevent the wiring members (COF 91 and FPC 92) and the wiring 93 from becoming longer.

As a second modified example, as shown in FIG. 11, an atmosphere communication port may be formed in the front side wall 62f, and an electromagnetic valve 64 that can selectively place the atmosphere communication port in an open state or a closed state may be disposed downstream of the inkjet head 41 in the transport direction. Note that components similar to those in the above-described embodiment and modified examples are indicated by the same reference numerals and will not be described. Also, in this modified example, the liquid volume sensor 6 and related components are omitted.

In this modified example, the relay board 380 is installed horizontally as shown in FIG. 11, and is connected to the control board 7 of the control unit 5 via an FPC 8. The relay board 380 is also located above the ink tank 61. In other words, the relay board 380 is installed so as to intersect with a vertical plane facing the transport direction (front-rear direction A2). The relay board 380 has a board body 381 having a rectangular planar shape, three connection parts 382-384, multiple head wiring 386, and valve wiring 388. These three connection parts 382-384, multiple head wiring 386, and valve wiring 388 are formed on the surface of the board body 381.

As shown in FIG. 11(b), the connection part 382 is formed at the right end of the substrate body 381, extending along the front-rear direction A2. One end of the FPC 8 arranged along the horizontal plane is connected to the connection part 382. The connection part 383 is formed at the left end of the substrate body 381, extending along the front-rear direction A2. The connection part 383 is connected to an FPC 92 connected to a COF 91 connected to a piezoelectric actuator 50 of the inkjet head 41.

As shown in FIG. 11, the connection part 384 is disposed near the center of the front end part of the substrate body 381. A wiring 93 connected to the electromagnetic valve 64 is connected to the connection part 384.

As shown in FIG. 11(b), the multiple head wirings 386 are formed to extend in the left-right direction A3 so as to connect the connection parts 382 and 383. The valve wirings 388 are formed so as to connect the connection parts 382 and 384. The multiple head wirings 386 are disposed at the connection part 382 behind the valve wirings 388 (upstream in the transport direction).

According to such a relay board 380, the connection positions of the multiple head signal lines 8a of the FPC 8 to the relay board 280 are arranged behind (upstream in the transport direction) the connection positions of the valve signal lines 8b to the relay board 280. And the electromagnetic valve 64 is arranged ahead of the inkjet head 41, that is, downstream in the transport direction. Therefore, in the transport direction, the connection positions of the valve signal lines 8b to the relay board 380 are closer to the electromagnetic valve 64, and the connection positions of the head signal lines 8a to the relay board 380 are closer to the inkjet head 41. Therefore, it is not necessary to cross the valve wiring 388 connected to the valve signal line 8b and the head wiring 386 connected to the head signal line 8a in the relay board 380, and it is possible to suppress noise interference. In addition, it is possible to suppress the lengthening of the wiring members (COF 91 and FPC 92) connecting from the relay board 380 to the piezoelectric actuator 50 of the inkjet head 41 and the wiring 93 connecting from the relay board 380 to the electromagnetic valve 64.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible within the scope of the claims. In the above embodiment, the relay board 80 is installed vertically along the up-down direction A1, but it does not have to be installed vertically as long as it intersects with the horizontal plane. In addition, the relay board 80 may be located at a position other than the rear of the ink tank 61. In the above first and second modified examples, the relay boards 280 and 380 are installed horizontally, but it does not have to be installed horizontally as long as it intersects with the vertical plane facing the transport direction. In addition, the relay boards 280 and 380 may be located at a position other than above the ink tank 61.

In the above-mentioned embodiment and the first and second modified examples, the head signal line 8a and the valve signal line 8b constitute multiple wirings formed on one FPC 8, but the head signal line 8a and the valve signal line 8b may be composed of separate wiring members. Even in this case, the same effect as described above can be obtained. Also, the ground line 8g does not have to be arranged between the head signal line 8a and the valve signal line 8b on the FPC 8.

In the above embodiment and the first and second modified examples, the present invention is used in a monochrome printer, but it may also be used in a color printer. In this case, the same effects as those described above can be obtained. The ink tank 61 may also have a communication passage that connects the atmosphere communication port 62e to the ink storage chamber 62a. In this case, the electromagnetic valve 64 only needs to be able to selectively place the atmosphere communication passage, which is composed of the communication passage and the atmosphere communication port 62e, in a communication state that connects the atmosphere communication passage to the outside, or in a blocked state that blocks communication with the outside. The ink tank 61 may not also be provided with an ink inlet 67.

In the above-mentioned embodiment and the first and second modified examples, the ink tank 61 and the inkjet head 41 are of an on-carriage type, in which the carriage 70 is mounted, but the present invention can also be applied to a line-type inkjet head in which the carriage 70 is not provided and the inkjet head is fixed. In this case as well, the same effects as those described above can be obtained.

The present invention can also be applied to a liquid ejection device having a liquid ejection head that ejects liquid other than ink. Also, it is possible to adopt an ejection energy imparting means other than the piezoelectric actuator 50, so long as it is possible to eject liquid from the nozzle by being driven based on a signal from the control unit 5. In this case, for example, a thermal type ejection energy imparting means may be adopted, in which a heating element heats the liquid ink in the nozzle, generating bubbles, and pushing the ink out of the nozzle to perform recording.

1. Printer (liquid ejection device)
5 Control unit 7 Control board 8 FPC
8a: Signal line for head 8b: Signal line for valve 8g: Ground line 20: Feeding section (transport mechanism)
35 Transport roller pair (transport mechanism)
36 Paper discharge roller pair (transport mechanism)
41 Inkjet head (liquid ejection head)
42 Nozzle 61 Ink tank (liquid storage section)
62a Ink storage chamber (liquid storage chamber)
62e Atmosphere communication port (atmosphere communication passage)
64 Solenoid valve (valve)
67 Ink inlet (liquid inlet)
69a Communication path (liquid flow path)
70 Carriage 71 Moving mechanism 80, 280, 380 Intermediate board 140 Memory 400 Pressure sensor (detection means)

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 having a control board and controlling the liquid ejection head and the valve;
A relay board disposed so as to intersect with a horizontal plane;
a head signal line connected to connect the control board and the relay board and for transmitting a signal from the control board to the liquid ejection head;
a valve signal line connected to connect the control board and the relay board and for transmitting a signal from the control board to the valve,
the valve is disposed above the liquid ejection head,
2. A liquid ejection device according to claim 1, wherein a connection position of the valve signal lines to the relay board is higher than a connection position of the head signal lines to the relay board. The liquid ejection device according to claim 1, characterized in that the relay substrate is installed along the vertical direction. The recording medium is further provided with a conveying mechanism that conveys the recording medium in a conveying direction,
3. The liquid ejection apparatus according to claim 1, wherein the relay board is disposed upstream of the liquid ejection head in the transport direction. The control unit is
a memory that stores a liquid count value, a reference value, and a liquid threshold value that indicates a pressure less than a withstand pressure value of a liquid meniscus formed in the nozzle, the liquid count value being updated according to the amount of liquid ejected from the nozzle;
a storage process for storing the liquid count value when the valve changes from the communicating state to the blocking state in the memory as the reference value;
a determination process for determining whether or not a difference between the liquid count value and the reference value reaches the liquid threshold value;
a communication process for controlling the valve so that the valve is in the communication state when it is determined in the determination process that the difference has reached the liquid threshold value;
4. The liquid ejection device according to claim 1, further comprising: a shutoff process for controlling the valve so that the valve is in the shutoff state, the shutoff process being performed after the communication process. The liquid storage chamber further includes a detection means for detecting a pressure in the liquid storage chamber,
The control unit is
a determination process for determining whether or not the pressure detected by the detection means reaches a predetermined value that is less than a withstand pressure value of the liquid meniscus formed in the nozzle;
a communication process for controlling the valve so that the valve is in the communication state when it is determined in the determination process that the pressure has reached the predetermined value;
4. The liquid ejection device according to claim 1, further comprising: a shutoff process for controlling the valve so that the valve is in the shutoff state, the shutoff process being performed after the communication process. 6. The liquid ejection apparatus according to claim 5 , wherein the detection means is a pressure sensor. a conveying mechanism that conveys the recording medium in a conveying direction;
a carriage supporting the liquid ejection head and the liquid storage unit;
7. The liquid ejection device according to claim 1, further comprising a movement mechanism that moves a carriage in a scanning direction that intersects with the transport direction. 8. The liquid ejection device according to claim 1, wherein the valve is an electromagnetic valve. 9. The liquid ejection device according to claim 1, wherein the head signal line and the valve signal line are configured as a plurality of wirings formed on a single flexible flat cable. 10. The liquid ejection device according to claim 9 , wherein the flexible flat cable includes a ground line that is grounded to the ground and is disposed between the head signal line and the valve signal line. 11. The liquid ejection device according to claim 1, wherein the liquid storage section further comprises a liquid inlet that connects the liquid storage chamber to the outside.

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