Image recording device

Abstract

To provide an image recording device that can prevent under-refilling from breaking meniscus.SOLUTION: Before performing discharge processing (S213), a controller determines whether or not a second condition is satisfied or not in S210, i.e, whether meniscus may break or not when executing the discharge processing. When the second condition is satisfied (S210:Yes), pressure in a storage part 21 is not returned to atmospheric pressure Po in communication processing (S211) and the discharge processing (S213) is executed. Meanwhile, when the second condition is not satisfied (S210:No), the discharge processing (S213) is executed, after the pressure in the storage part 21 is returned to the atmospheric pressure Po in the communication processing (S211).SELECTED DRAWING: Figure 11

Description

Technical Field

[0001] The present invention relates to an image recording apparatus.

Background Art

[0002] Patent Document 1 describes an inkjet printer. The printer records an image on a sheet by ejecting ink from a head onto the sheet. In response to ink consumption due to image recording, the ink in the tank is supplied to the ink chamber in the head through a flow path.

[0003] An air communication hole is formed in the outer wall of the tank. During image recording, the air communication hole is closed by a valve provided in the tank. When ink ejection is repeated in this state, the negative pressure in the tank and the head increases, and there is a risk that the meniscus of the ink formed at the nozzle breaks. Therefore, in the printer, prior to image recording, the amount of ink to be ejected in image recording is estimated. When the estimated amount reaches a threshold value, the valve is opened. As a result, the inside of the tank returns to atmospheric pressure (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the printer of Patent Document 1, there is a risk of meniscus break due to underfilling. Specifically, when the amount of ink ejected from the head per unit time (hereinafter also referred to as "ejection amount") increases, the amount of ink supplied from the tank to the head cannot keep up with the ejection amount due to flow path resistance. This phenomenon is referred to as "underfilling" in this specification. When the negative pressure in the tank and the head rises too much due to underfilling, the meniscus breaks.

[0006] The present invention has been made in view of the above circumstances, and its purpose is to provide an image recording device capable of preventing meniscus breakage due to under-refill. [Means for solving the problem]

[0007] (1) The image recording device of the present invention comprises a head having a plurality of nozzles, a storage unit having a liquid storage chamber and an atmospheric communication passage connecting the storage chamber to the outside, a liquid flow path connecting the storage chamber and the plurality of nozzles so that liquid can flow through it, a switching mechanism that switches the state of the atmospheric communication passage between a connected state in which the storage chamber is in communication with the outside and a non-connected state in which the storage chamber is not in communication with the outside, and a controller, wherein the controller, based on the fact that the amount of liquid discharged from the plurality of nozzles within a first predetermined time is a first amount equal to or greater than a first predetermined amount, switches the switching mechanism The process involves performing a connection process to return the atmospheric communication passage to a connected state and then to a disconnected state, and after the connection process, performing a first discharge process to discharge a first amount of liquid from the plurality of nozzles within a first predetermined time while the atmospheric communication passage is in a disconnected state. Based on the fact that the amount of liquid discharged from the plurality of nozzles within the first predetermined time is a second amount less than the first predetermined amount, the process involves performing a second discharge process to discharge a second amount of liquid from the plurality of nozzles within the first predetermined time while maintaining the disconnected state without returning the atmospheric communication passage to a connected state.

[0008] According to the above process, when the discharge volume is the first volume, the first discharge process is performed after the storage chamber is returned to atmospheric pressure by the communication process. This prevents the pressure in the liquid flow path from falling below the meniscus resistance pressure after the first discharge process is performed, and as a result, meniscus break due to under-refill does not occur.

[0009] (2) The controller performs a determination process to determine whether the amount of liquid discharged from the plurality of nozzles within the first predetermined time is equal to or equal to a first predetermined amount, and if the determination process determines that it is equal to or equal to the first predetermined amount, it performs the communication process and the first discharge process, and if the determination process determines that it is not equal to or equal to the first predetermined amount, it performs the second discharge process.

[0010] (3) The controller performs a quantity calculation process to calculate the amount of liquid discharged from the multiple nozzles within the first predetermined time based on the image data of the unit recording area, and in the determination process, it determines whether the amount of discharged calculated by the quantity calculation process is equal to or greater than the first predetermined amount.

[0011] (4) The controller performs the following: an acquisition process to acquire the pre-discharge pressure, which is the pressure in the storage chamber before the execution of the first discharge process or the second discharge process; an amount calculation process to calculate the amount of liquid to be discharged from the plurality of nozzles within the first predetermined time based on the image data of a unit image area; and a pressure calculation process to calculate the post-discharge pressure, which is the pressure in the liquid flow path after the amount of liquid has been discharged from the plurality of nozzles, based on the discharge amount calculated by the amount calculation process and the pre-discharge pressure acquired by the acquisition process. The controller then performs the communication process and the first discharge process if the post-discharge pressure calculated by the pressure calculation process has reached a threshold, and performs the second discharge process if the post-discharge pressure calculated by the pressure calculation process has not reached a threshold.

[0012] (5) In the pressure calculation process, the controller calculates the amount of pressure change in the liquid flow path before and after the discharge of the liquid based on the discharge amount calculated by the amount calculation process and the resistance value of the liquid flow path, and calculates the post-discharge pressure based on the calculated amount of pressure change and the pre-discharge pressure obtained by the acquisition process.

[0013] (6) The image recording device further comprises a transport mechanism for transporting a sheet in the transport direction, and a carriage on which the head is mounted and moves in a scanning direction intersecting the transport direction, wherein the image data of the unit image region is image data for one pass in the scanning direction, and the controller determines the discharge amount in the quantity calculation process based on the image data for one pass in the scanning direction.

[0014] (7) The image recording device further comprises a transport mechanism for transporting the sheet in the transport direction, the image data of the unit image area is the image data of one page of the sheet, and the controller determines the discharge amount in the quantity calculation process based on the image data of one page of the sheet.

[0015] (8) The head further comprises a plurality of other nozzles different from the plurality of nozzles, the storage unit further comprises a storage chamber different from the storage chamber, the atmospheric communication passage further connects the other storage chamber to the outside of the other storage chamber, the image recording device further comprises a liquid flow path that connects the other storage chamber and the other plurality of nozzles in a liquid flowable manner, in the communication state the other storage chamber is further connected to the outside, in the non-communication state the other storage chamber is not further connected to the outside, the controller determines that the amount of liquid discharged from the plurality of nozzles within the first predetermined time is the first amount which is equal to or equal to the first predetermined amount, or the other plurality of nozzles within the first predetermined time Based on the fact that the amount of liquid discharged from several nozzles is a third amount greater than or equal to a first predetermined amount, after performing the communication process, the third amount of other liquid is further discharged from the other multiple nozzles in the first discharge process within the first predetermined time while the atmospheric communication passage is in the communication state, and based on the fact that the amount of liquid discharged from the multiple nozzles within the first predetermined time is less than the first predetermined amount, and the amount of liquid discharged from the other multiple nozzles within the first predetermined time is a fourth amount less than the first predetermined amount, the second discharge process further discharges the fourth amount of liquid from the other multiple nozzles within the first predetermined time while maintaining the non-communication state without making the atmospheric communication passage into a communication state.

[0016] When the discharge volume is the first or third volume, the first discharge process is performed after the storage chamber and other storage chambers are returned to atmospheric pressure through a communication process. Therefore, after the first discharge process is performed, it is prevented that the pressure in the liquid flow path will fall below the meniscus pressure resistance of multiple nozzles. Similarly, it is prevented that the pressure in other liquid flow paths will fall below the meniscus pressure resistance of other multiple nozzles. As a result, meniscus breakage due to under-refilling does not occur.

[0017] (9) The head further comprises a plurality of nozzles different from the plurality of nozzles, the storage unit further comprises a storage chamber different from the storage chamber, and another atmospheric communication passage that connects the other storage chamber to the outside, the image recording device further comprises another liquid flow path that connects the other storage chamber and the other plurality of nozzles so that liquid can flow through it, the switching mechanism causes the other atmospheric communication passage to communicate with the outside when it is in the communication state, and to not communicate with the outside when it is in the non-communication state, the controller determines that the amount of liquid discharged from the plurality of nozzles within the first predetermined time is the first predetermined amount or more, or that the amount of liquid discharged from the other plurality of nozzles within the first predetermined time is the first predetermined amount Based on the third amount being greater than or equal to a predetermined amount, the above communication process further involves the switching mechanism to connect the other air passages and then disconnect them, and after the communication process, the first discharge process further involves the other air passages being disconnected and then discharging the third amount of liquid from the other nozzles within the first predetermined time, and based on the fact that the amount of liquid discharged from the multiple nozzles within the first predetermined time is less than the first predetermined amount, and the amount of liquid discharged from the other nozzles within the first predetermined time is less than the first predetermined amount, the second discharge process further involves the other air passages being disconnected and then discharging the fourth amount of liquid from the other nozzles within the first predetermined time.

[0018] (10) The controller, upon receiving the image data, further performs an initialization process to return the atmospheric communication passage to the connected state and then to the disconnected state using the switching mechanism.

[0019] The initialization process brings the storage chamber to atmospheric pressure, making it less likely for the pressure in the liquid flow path to reach the meniscus pressure limit. In other words, the number of times the communication process needs to be executed is reduced.

[0020] (11) The controller, based on the fact that the amount of liquid discharged from the plurality of nozzles in a first predetermined time is equal to or greater than the first predetermined amount, and that the amount of liquid discharged per first predetermined time when that amount of liquid is discharged from the plurality of nozzles within a second predetermined time which is longer than the first predetermined time is less than the first predetermined amount, performs a third discharge process in which the first amount of liquid is discharged from the plurality of nozzles within the second predetermined time while maintaining the non-communication state without opening the air passage.

[0021] The execution of the third discharge process reduces the number of times the communication process is performed.

[0022] (12) The image recording device further includes a memory for storing the pre-discharge pressure, and the controller further performs a pressure update process in which, depending on whether the first discharge process or the second discharge process has been executed, the controller determines the current pressure of the storage chamber based on the first quantity and the pre-discharge pressure stored in the memory, and updates the pre-discharge pressure stored in the memory with the determined current pressure, and in the pressure calculation process, the controller determines the post-discharge pressure based on the discharge quantity calculated by the quantity calculation process and the pre-discharge pressure stored in the memory.

[0023] Since the pre-discharge pressure can be obtained through calculation, the number of sensors can be reduced.

[0024] (13) In response to the execution of the above communication process, a reset process is further executed to reset the pre-discharge pressure stored in the memory.

[0025] (14) The image recording apparatus of the present invention includes a head having a plurality of nozzles, a liquid storage chamber, a storage unit having an air communication passage that communicates the storage chamber with the outside, the storage chamber, and a liquid flow path that connects the storage chamber and the plurality of nozzles so that liquid can flow through them. The apparatus also includes a switching mechanism that switches the state of the air communication passage between a communication state in which the storage chamber communicates with the outside and a non-communication state in which the storage chamber does not communicate with the outside, and a controller. The controller executes a fourth discharge process of discharging a fifth amount of liquid from the plurality of nozzles within a fourth predetermined time while keeping the air communication passage in the non-communication state without switching it to the communication state, based on the fact that the discharge amount of liquid from the plurality of nozzles within a third predetermined time is a fifth amount that is equal to or greater than a third predetermined amount, and the discharge amount per third predetermined time when discharging liquid of the discharge amount from the plurality of nozzles within a fourth predetermined time that is longer than the third predetermined time is less than the third predetermined amount. The controller also executes a fifth discharge process of discharging a sixth amount of liquid from the plurality of nozzles within the third predetermined time while maintaining the non-communication state without switching the air communication passage to the communication state, based on the fact that the discharge amount of liquid from the plurality of nozzles within the third predetermined time is a sixth amount that is less than the third predetermined amount. [Effects of the Invention]

[0026] According to the present invention, it is possible to provide an image recording apparatus that can prevent meniscus breakage due to underfilling. [Brief Description of the Drawings]

[0027] [Figure 1] (A) is an external perspective view of the printer 100, and (B) is a schematic diagram showing the internal configuration of the printer 100. [Figure 2] A plan view showing the platen 16 in FIG. 1 and its surroundings. [Figure 3] (A) is a bottom view of the recording head 17, and (B) is a plan view of the recording head 17. [Figure 4] A cross-sectional view of the recording head 17 cut along the line A-A in FIG. 3(A) as viewed from the rear. [Figure 5] A front view showing the storage section 21 and the cap 27 at the cap position. [Figure 6] Right side view of the storage unit 21 and the recording head 17. [Figure 7] (A) is a cross-sectional view of the storage section 21 as seen from the front, cut along line BB in Figure 6, and (B) is a cross-sectional view of the storage section 21 as seen from the front, cut along line CC in Figure 6. [Figure 8] A front view showing the storage section 21 located away from the opening member 29, and the cap 27 at a separate position. [Figure 9] Block diagram of printer 100. [Figure 10] (A) is a flowchart of the ink injection process, and (B) is a flowchart of the first part of the image recording process. [Figure 11] A flowchart for the second part of the image recording process. [Figure 12] A graph showing the change in pressure within manifold 177A over time. [Figure 13] A schematic diagram showing the configuration of the storage section 21 according to the second modified example. [Figure 14] Flowchart of the second part of the image recording process related to the third modified example. [Figure 15] A graph showing the change in pressure within manifold 177A over time in the third modified example. [Figure 16] A flowchart of the second part of the image recording process related to the fourth modified example. [Figure 17] A schematic diagram showing the contents of the discharge rate threshold table.

[0028] [Embodiment] Hereinafter, a printer 100 (an example of an image recording device) according to an embodiment of the present invention will be described with reference to the drawings. The following embodiment is merely an example of the present invention, and it goes without saying that the embodiment of the present invention can be appropriately modified without changing the gist of the present invention. In the following description, the movement from the starting point to the ending point of the arrow is expressed as "direction," and the movement along the line connecting the starting point and the ending point of the arrow is expressed as "orientation."

[0029] The vertical direction 7 is defined based on the state in which the printer 100 is installed for use (the state in Figure 1), the front-to-back direction 8 is defined with the surface on the housing 11 where the opening 12 is formed being the front 111, and the left-to-right direction 9 is defined when viewing the printer 100 from the front. The vertical direction 7, the front-to-back direction 8, and the left-to-right direction 9 are orthogonal to each other.

[0030] [Printer 100 Configuration] As shown in Figure 1, the printer 100 includes a supply tray 13, a feed roller 14, a transport roller pair 15, a platen 16, a recording head 17, an ejection roller pair 18, an ejection tray 19, a transport path 20, and a storage unit 21, and records an image on a sheet S using an inkjet method.

[0031] The supply tray 13 and the discharge tray 19 are installed inside the housing 11 through the opening 12. The supply tray 13 is located below the discharge tray 19. Sheets S, such as paper or resin film, are loaded onto the supply tray 13. The rotation of the feed roller 14 transports the sheets S upward within the transport path 20 and feeds them to the transport roller pair 15. The transport roller pair 15 rotates to feed the sheets S onto the platen 16 at the front. The recording head 17 ejects multiple colors of ink onto the sheets S on the platen 16. The multiple colors are cyan, magenta, yellow, and black. As a result, a full-color image is recorded on the sheets S. The sheet S with the recorded image is fed to the discharge roller pair 18. The discharge roller pair 18 rotates to feed the sheets S towards the discharge port 112 at the front. The sheets S are discharged from the discharge port 112 into the discharge tray 19. Furthermore, as the ink of each color is consumed by the recording head 17, ink of each color is replenished from the storage unit 21 to the recording head 17.

[0032] [Conveying roller pair 15, discharge roller pair 18 (Example of conveying mechanism)] As shown in Figure 1(B), in the conveyor roller pair 15, the drive roller 151 is located slightly ahead of the downstream end of the conveyor path 20 and contacts the pinch roller 152 from above. In the discharge roller pair 18, the drive roller 181 is located ahead of the conveyor roller pair 15 and slightly behind the discharge port 112 and contacts the spur roller 182 from below. The drive rollers 151 and 181 rotate around their respective axes. The pinch roller 152 and spur roller 182 rotate along with the drive rollers 151 and 181.

[0033] [Platen 16] The platen 16 is located between the pinch rollers 152 and the drive rollers 181 in the front-rear direction 8. As shown in Figure 2, the platen 16 has a roughly rectangular shape that is elongated in the left-right direction 9 when viewed from above, and supports the sheet S fed out from the conveyor roller pair 15 from below.

[0034] [Guide rails 23A, 23B, carriage 24, transport mechanism 25] As shown in Figures 1(B) and 2, guide rails 23A and 23B extend in the left-right direction 9 above the front and rear ends of the platen 16. The carriage 24 is spanned between the guide rails 23A and 23B and slides along the guide rails 23A and 23B in the left-right direction 9.

[0035] As shown in Figure 2, the transport mechanism 25 (part of the switching mechanism) generates and transmits power to move the carriage 24 in the left-right direction 9. In detail, in the transport mechanism 25, pulleys 251A and 251B are rotatably mounted around an axis along the vertical direction 7 near the left and right ends of the guide rail 23A. An endless belt 252 is wrapped around the pulleys 251A and 251B. The carriage 24 is connected to the endless belt 252. Power from a CR motor 253, such as a DC motor, is transmitted to the right pulley 251A. As a result, pulley 251A rotates, and the endless belt 252 rotates along the left-right direction 9 between pulleys 251A and 251B. This causes the carriage 24 to move in the left-right direction 9.

[0036] [Linear Encoder 26] The printer 100 further includes a linear encoder 26. In the linear encoder 26, the encoder strip 261 extends in the left-right direction along the endless belt 252 and has a scale consisting of a light-transmitting portion and a light-blocking portion. A photointerrupter 262 is mounted on the carriage 24 and optically reads the scale of the encoder strip 261. The photointerrupter 262 outputs a signal indicating the reading result.

[0037] [Recording head 17] As shown in Figure 1(B), the recording head 17 (an example of a head) is generally rectangular in shape and has a nozzle surface 171 and an upper surface 174. The recording head 17 is mounted on the carriage 24 such that the nozzle surface 171, which is the lower surface of the recording head 17, faces the platen 16 above. As shown in Figure 3(A), a nozzle row 172A (an example of multiple nozzles) is formed on the nozzle surface 171 along the left end of the nozzle surface 171. The nozzle row 172A consists of a number of nozzles 173A arranged in the front-to-back direction 8. Magenta ink can be ejected from the number of nozzles 173A. In Figure 3(A), one nozzle is labeled with the reference numeral "173A".

[0038] As shown in Figure 3(B), an inlet 175A is formed on the upper surface 174 behind the nozzle row 172A, and is open upwards. The inlet 175A is covered with a filter 176A to prevent foreign matter (such as air bubbles) from entering the recording head 17.

[0039] [Manifold 177A~177D etc.] As shown in Figures 3 and 4, a manifold 177A (an example of a liquid flow path) is formed inside the recording head 17. The manifold 177A extends slightly to the right of the nozzle row 172A in the left-right direction 9, and front-back between the inlet 175A and the foremost nozzle 173A in the front-back direction 8. The rear end of the manifold 177A is connected to the inlet 175A so that ink can flow through it. The manifold 177A is connected so that ink can flow through it via a number of nozzles 173A and a number of pressure chambers 178A. Each of the pressure chambers 178A is provided with a piezoelectric element 179A (see Figure 4). By selectively applying voltage to multiple piezoelectric elements 179A, ink in the corresponding pressure chamber 178A is ejected from the nozzle 173A. In Figure 3(A), one pressure chamber is labeled with the reference numeral "178A".

[0040] As shown in Figure 3, the recording head 17 has a nozzle row 172B (an example of several other nozzles), an inlet 175B, a manifold 177B, and a pressure chamber 178B for cyan ink. Similarly, the recording head 17 has a nozzle row 172C, an inlet 175C, a manifold 177C, and a pressure chamber 178C for yellow ink, and a nozzle row 172D, an inlet 175D, a manifold 177D, and a pressure chamber 178D for black ink. The nozzle rows 172B-172D, inlets 175B-175D, manifolds 177B-177D, and pressure chambers 178B-178D are similar in configuration to the nozzle row 172A, inlet 175A, manifold 177A, and pressure chamber 178A, so their respective descriptions will be omitted. Note that at least one of nozzle rows 172B to 172D may be another example of multiple nozzles. At least one of nozzle rows 172A, 172C, and 172D may be another example of multiple nozzles.

[0041] [Storage section 21] As shown in Figures 5 to 7, the storage unit 21 is installed above the recording head 17 and comprises an outer wall 211, upper indicators 212A to 212D, lower indicators 213A to 213D, a lid 214A to 214D, partition walls 215A to 215D (see Figure 7), and cylindrical walls 216A to 216D (see Figure 7).

[0042] [Outer wall 211, through holes 218A~218D] As shown in Figures 5 to 7, the outer wall 211 is made of a translucent material (e.g., transparent resin) and separates the internal space 217A (see Figure 7) of the storage section 21 from the external space. In the outer wall 211, the bottom wall 211A extends along the front-to-back direction 8 and the left-to-right direction 9. The front wall 211B (see Figure 6) extends upward from the front edge of the bottom wall 211A. The rear wall 211C (see Figure 6) extends from the rear edge of the bottom wall 211A to above the front wall 211B. The upper wall 211D extends from the upper edge of the front wall 211B to slightly behind the lids 214A to 214D. The upper wall 211E extends from the upper edge of the rear wall 211C to directly above the rear edge of the upper wall 211D. The front wall 211F widens between the trailing edge of the upper wall 211D and the leading edge of the upper wall 211E. The left wall 211G and the right wall 211H (see Figure 4) close off the left and right ends of the storage section 21, respectively. Through holes 218A to 218D are formed in the upper wall 211D at intervals in the left-right direction 9, as shown in Figure 7(B).

[0043] [Bulkhead 215A~215D] As shown in Figure 7, bulkheads 215A to 215D divide the internal space 217A into storage chambers 219A to 219D, an air chamber 219E, and a valve chamber 219F. Bulkhead 215A is connected to the bottom wall 211A, the front wall 211B, and the rear wall 211C, and extends in the front, back, up, and down directions. The upper end of bulkhead 215A connects to the upper wall 211D between the through holes 218A and 218B (see Figure 7(B)), but does not connect to the upper wall 211E (see Figure 7(A)). Bulkheads 215B and 215C have the same shape as bulkhead 215A when viewed from the left and right directions. Bulkhead 215B extends in the front, back, up, and down directions between the through holes 218B and 218C, and bulkhead 215C extends in the front, back, up, and down directions between the through holes 218C and 218D. With the above configuration, each of the storage chambers 219A to 219D can communicate with the outside of the storage section 21 via the air chamber 219E, the valve chamber 219F, and the atmospheric communication hole 218E.

[0044] [Storage chambers 219A~219D, air chamber 219E, atmospheric communication port 218E] In the internal space 217A, storage chamber 219A is the space between the left wall 211G and the partition wall 215A, and stores magenta ink. Storage chamber 219B is the space between partition walls 215A and 215B, and stores cyan ink. Storage chamber 219C is the space between partition walls 215B and 215C, and stores yellow ink. Storage chamber 219D is the space between partition wall 215C and the right wall 211H, and stores black ink. Air chamber 219E is the space in the internal space 217A above partition walls 215A to 215C. As shown in Figure 6, in the right wall 211H, an atmospheric communication hole 218E (an example of an atmospheric communication passage) is formed at a position above the upper wall 211D. The atmospheric communication hole 218E penetrates the right wall 211H and connects the internal space 217A of the storage section 21 with the outside of the storage section 21.

[0045] [Outlet 2111A~2111D] As shown in Figure 7(A), outlets 2111A to 2111D are formed at the bottom of the storage chambers 219A to 219D. The outlets 2111A to 2111D are connected to the inlets 175A to 175D on the recording head 17 side (see Figure 3(B)) so that ink can flow through them. As a result, storage chamber 219A is connected so that magenta ink can flow through it via the manifold 177A and the outlets 2111A and inlets 175A. Similarly, storage chambers 219B to 219D are connected to the manifolds 177B to 177D so that ink of the corresponding color can flow through them.

[0046] [Bulkhead 215D, valve chamber 219F] As shown in Figure 7(A), the bulkhead 215D extends downward from a position to the left of the right wall 211H on the upper wall 211E, and faces the atmospheric communication hole 218E in the left-right direction 9. The bulkhead 215D partitions the valve chamber 219F between itself and the right wall 211H.

[0047] [Various indicators 212A~212D, 213A~213D] As shown in Figure 5, the upper indicators 212A to 212D and the lower indicators 213A to 213D are each formed on the outer surface of the front wall 211B. The upper indicators 212A to 212D indicate the liquid level position of the maximum amount of ink that can be stored in the storage chambers 219A to 219D (hereinafter also referred to as "maximum storage amount") QM1 to QM4. The lower indicators 213A to 213D indicate the liquid level position in the storage chambers 219A to 219D where ink replenishment is required.

[0048] [Cylinder wall 216A~216D, lid 214A~214D] As shown in Figure 7(B), the cylindrical wall 216A protrudes vertically 7 from the periphery of the through hole 218A at the upper wall 211D, defining the ink supply passage 2110A. The ink supply passage 2110A extends from the ink supply port (i.e., the upper opening in the cylindrical wall 216A) to the storage chamber 219A. The cylindrical walls 216B to 216D protrude from the periphery of the through holes 218B to 218D in the same manner as the cylindrical wall 216A, defining the ink supply passages 2110B to 2110D.

[0049] As shown in Figures 5 to 7, the lids 214A to 214D can be attached to or detached from the upper ends of the cylinder walls 216A to 216D by user operation, thereby liquid-tightly closing or opening the ink supply passages 2110A to 2110D.

[0050] [Cap 27] As shown in Figure 2, the cap 27 is located in the home position to the right of the platen 16 in the left-right direction 9. As shown in Figures 5 and 8, the cap 27 is supported by the frame 113 inside the housing 11 via a lifting mechanism 271, and moves up and down in the vertical direction 7 between the cap position (see Figure 5) and the separated position (see Figure 8) due to the power generated by the lifting mechanism 271. In the cap position, the cap 27 abuts against the nozzle surface 171 of the recording head 17 in the home position and covers the nozzle row 172A to 172D. The separated position is a position lower than the cap position. In the separated position, the cap 27 is separated downward from the nozzle surface 171 of the recording head 17 in the home position.

[0051] [Valve unit 28, opening member 29] As shown in Figure 7(A), the printer 100 further comprises a valve unit 28. In the valve unit 28, a compression coil spring 281 is attached to the valve chamber 219F such that its axis is parallel to the left-right direction 9. The left end of the compression coil spring 281 is fixed to the partition wall 215D. In the valve unit 28, a valve body 282 is attached to the right end of the compression coil spring 281, and when the opening member 29 (see Figure 5) is not in contact, the valve body closes the atmospheric communication hole 218E in the right wall 211H with the biasing force of the compression coil spring 281, using the periphery of the atmospheric communication hole 218E in the right wall 211H as a valve seat. As a result, the atmospheric communication hole 218E is in a non-communication state, so that each of the storage chambers 219A to 219D does not communicate with the outside of the storage section 21.

[0052] As shown in Figures 5 and 8, a side frame 114 is provided inside the housing 11. The side frame 114 extends to the right of the cap 27 in the front-to-back direction 8 and the up-to-down direction 7, and faces the right wall 211H of the storage section 21. The side frame 114 supports, for example, the guide rails 23A and 23B. A rod-shaped opening member 29 (part of the switching mechanism) extending in the left-to-right direction 9 protrudes to the left from the side frame 114 and has a cylindrical shape with a smaller diameter than the atmospheric communication hole 218E. As the recording head 17 reaches the home position from the right, the opening member 29 is inserted into the atmospheric communication hole 218E and comes into contact with the valve body 282. While the recording head 17 is stopped at the home position, the valve body 282 moves away from the right wall 211H against the biasing force of the compression coil spring 281 due to the contact force received from the opening member 29. As a result, the valve body 282 opens the atmospheric communication hole 218E. In this way, the opening member 29 switches the closed valve body 282 to an open state, and the atmospheric communication hole 218E is opened so that each storage chamber 219A to 219D communicates with the outside of the storage section 21.

[0053] [Various motors 30-32, controller 33] As shown in Figure 9, the printer 100 further includes a feed motor 30, a PF motor 31, and a lifting motor 32, which are DC motors. The feed motor 30 generates power to rotate the feed roller 14. The PF motor 31 generates power to rotate the drive rollers 151 and 181. The lifting motor 32 generates power to move the cap 27 up and down using the lifting mechanism 271.

[0054] The printer 100 further includes a controller 33. The controller 33 has a CPU, ROM, RAM, EEPROM, and ASIC, which are connected by an internal bus. The ROM stores the control program for the printer 100, etc. The CPU executes the program while using the RAM and EEPROM as workspaces.

[0055] The controller 33 stores the discharge volume counters 301A to 301D, the pressure counter 302, and the air volume counter 303 in an EEPROM or the like. The discharge volume counters 301A, 301B, 301C, and 301D are used to accumulate the discharge volumes of magenta ink, cyan ink, yellow ink, and black ink, respectively. The pressure counter 302 is used to accumulate the pressure in the storage unit 21. The air volume counter 303 is used to accumulate the volume in the storage unit 21.

[0056] [Printer 100 Operation] The operation of printer 100 will be described in detail below, in the order of ink injection process and image recording process.

[0057] [Ink injection process] The controller 33 performs an ink injection process in response to the initial power-on of the printer 100. The ink injection process consists of steps S101 to S104, as shown in Figure 10(A).

[0058] In the movement process of S101, the controller 33 moves the recording head 17 in the left-right direction 9 by controlling the CR motor 253, and stops the rotation of the CR motor 253 when the recording head 17 reaches the home position (see Figure 5). Subsequently, the controller 33 moves the cap 27 from the separated position to the cap position by controlling the lifting motor 32. While the recording head 17 is in the home position, the atmospheric communication hole 218E is kept open by the opening member 29.

[0059] In the warning process of S102, the controller 33 displays a message on the printer 100's display (not shown) prompting the user to inject ink into each storage chamber 219A to 219D. In response to the message, the user opens the lid 214A, injects magenta ink into storage chamber 219A up to the position of the upper indicator 212A, and closes the lid 214A. The other color inks are injected in the same manner. After that, the user inputs that ink injection is complete into the printer 100's control panel (not shown) (S103).

[0060] In the initial setup process of S104, the controller 33 resets the count values ​​C11 to C14 of each discharge amount counter 301A to 301D. The count values ​​C11 to C14 are reset to zero, for example. In the initial setup process, the controller 33 resets the count value C3 of the air volume counter 303 to a value corresponding to volume Vb. Volume Vb is the volume of air in the storage section 21 when the maximum storage amount QM1 to QM4 of ink is stored.

[0061] [Image recording processing] In the standby state of the printer 100, the recording head 17 waits in the home position (see Figure 5). The cap 27 is in the cap position.

[0062] An information processing device (not shown) is connected to the printer 100 for data communication. In the information processing device, the printer driver generates a plurality of pass data, each representing a pass image. Each pass image is an image recorded in a unit recording area of ​​the sheet S as the recording head 17 moves one pass in the left-right direction 9 (an example of the scanning direction). That is, in this embodiment, the unit recording area is the area of ​​the sheet S where an image is recorded by moving one pass. Based on each pass data, the printer driver generates ejection instruction information for each pass. Each ejection instruction information indicates the timing and amount of ink ejected from nozzles 173A to 173D for recording the pass image. The printer driver generates a print job including the ejection instruction information for each pass and sends it to the printer 100.

[0063] In the printer 100, the controller 33 starts executing image recording processing with the print job received from the information processing device as the target of processing. The image recording processing consists of steps S201 to S219, as shown in Figures 10(B) and 11.

[0064] In S201, the controller 33 counts the amount of magenta ink ejected when recording each pass image (hereinafter also referred to as "magenta ejection amount") Q11, Q12, ... Q1n, based on the ejection amount contained in each ejection instruction information. n is the total number of ejection instruction information included in the processing target. Similarly, the ejection amounts of cyan ink Q21, ... Q2n, yellow ink Q31, ... Q3n, and black ink Q41, ... Q4n are also counted. Each of the ejection amounts Q11, ... Q1n, Q21, ... Q2n, Q31, ... Q3n, Q41, ... Q4n is an example of the amount of liquid ejected from multiple nozzles within a predetermined time. Also, S201 is an example of the amount calculation process.

[0065] In S202, the controller 33 calculates the total ejection amount QT1 of magenta ink. The total ejection amount QT1 is the sum of the ejection amounts Q11, ... Q1n and the amount of magenta ink ejected in the flushing in S205. In S202, the controller 33 calculates the remaining amount QR1 of magenta ink in the storage chamber 219A after image recording processing by subtracting the total ejection amount QT1 from the maximum storage amount QM1. Similarly, the total ejection amount QT2 and remaining amount QR2 of cyan ink, the total ejection amount QT3 and remaining amount QR3 of yellow ink, and the total ejection amount QT4 and remaining amount QR4 of black ink are also calculated.

[0066] In S203, the controller 33 determines whether the first condition is met. The first condition is that the total ejection amount QTi of each color ink does not exceed the remaining amount QRI. i is 1, 2, 3, or 4. If the controller determines that the first condition is not met (No in S203), the controller 33 proceeds to S204, assuming that there will be insufficient ink during the image recording process. If the controller determines that the first condition is met (Yes in S203), the controller 33 proceeds to S205.

[0067] In S204, the controller 33 performs the ink injection process (see Figure 10(A)) and then proceeds to S205.

[0068] In step S205, the controller 33 performs a flushing process. During the flushing process, the controller 33 moves the cap 27 to a detached position, and then moves the recording head 17 directly above the ink receptacle 272 (see Figure 2). The ink receptacle 272 is located to the left of the platen 16. Subsequently, the controller 33 ejects each color ink from the recording head 17 towards the ink receptacle 272.

[0069] In the communication process in S206, the controller 33 moves the recording head 17 in the left-right direction 9, and when the recording head 17 reaches the origin position, it begins to determine the left-right position of the recording head 17 based on the output signal of the linear encoder 26. From this point onward, the determination of the left-right position of the recording head 17 is performed periodically until the image recording process is completed. Subsequently, the controller 33 moves the recording head 17 to the home position (see Figure 5) based on the output signal of the linear encoder 26, thereby opening the atmospheric communication hole 218E with the opening member 29. In the communication process, the controller 33 further resets the count value C2 of the pressure counter 302 to atmospheric pressure Po.

[0070] In the S207 lead-out process, the controller 33 controls the feed motor 30 and the PF motor 31 to transport the top sheet S in the supply tray 13 to the lead-out position directly below the recording head 17. The lead-out position is the position on the platen 16 where the leading unit recording area in the transport direction of the sheet S is directly below the nozzle rows 172A to 172D and facing each other.

[0071] In S208, the controller 33 identifies the discharge amounts Q1j, Q2j, Q3j, Q4j (where j = 1, 2, ..., n) for each color included in the discharge instruction information to be processed in RAM. For example, during the first execution of S208, discharge amounts Q11 to Q41 are identified. The controller 33 further determines the differential pressures DP1j, DP2j, DP3j, DP4j. The differential pressure DP1j is the differential pressure between the storage chamber 219A and the manifold 177A when magenta ink is discharged at a discharge amount Q1j (an example of the pressure change in the liquid flow path), and DP1j is calculated from Q1j × R1. R1 is the flow path resistance (fixed value) of the manifold 177A. The differential pressure DP2j for cyan is calculated from Q2j × R2. The differential pressure PD3j for yellow is calculated from Q3j × R3. The differential pressure PD4j for black is calculated from Q4j × R4. R2, R3, and R4 are the flow resistances of manifolds 177B, 177C, and 177D. S208 is also part of the pressure calculation process.

[0072] In S209, the controller 33 obtains count values ​​C11 to C14 from the discharge volume counters 301A to 301D, obtains the count value C2 from the pressure counter 302 as the pre-discharge pressure, and obtains the count value C3 from the air volume counter 303. The controller 33 then calculates the post-discharge pressure P1j. The post-discharge pressure P1j is the pressure of the magenta ink in the manifold 177A immediately after discharging a discharge volume Q1j of magenta ink, and is the pressure before magenta ink from the storage chamber 219A is replenished in the manifold 177A. P1j is calculated from C2 + DP1j. Similarly, the post-discharge pressure P2j for cyan ink is C2 + DP2j. The post-discharge pressure P3j for yellow ink is C2 + DP3j. The post-discharge pressure P4j for black ink is C2 + DP4j. Note that S209 is an example of the acquisition process and is also part of the pressure calculation process.

[0073] As shown in Figure 11, in S210, the controller 33 determines whether the second condition is met. The second condition is that the post-discharge pressure P1j is greater than or equal to the pressure threshold T11, the post-discharge pressure P2j is greater than or equal to the pressure threshold T12, the post-discharge pressure P3j is greater than or equal to the pressure threshold T13, and the post-discharge pressure P4j is greater than or equal to the pressure threshold T14. The pressure threshold T11 is set to a pressure slightly higher than the pressure withstand capability of the meniscus formed with magenta ink in each nozzle 173A. The pressure thresholds T12, T13, and T14 are for cyan ink, yellow ink, and black ink, respectively, and are determined in the same way as the pressure threshold T11. Note that the meniscus pressure withstand capability is also determined by the wettability and viscosity of the ink, so it is preferable to set the pressure threshold for each color. If the controller 33 determines that the second condition is not met (No in S210), it executes S211 because a meniscus break may occur in any of the nozzle rows 172A to 172D due to under-refill. If the controller 33 determines that the second condition is met (Yes in S210), it executes S212.

[0074] In the communication process of S211, the controller 33 opens the atmospheric communication hole 218E using the opening member 29 in the same manner as in S206. As a result, the pressure inside the storage section 21 returns to atmospheric pressure Po, so that even if each color ink is ejected based on the ejection instruction information for the processing target, meniscus break due to under-refill does not occur. The controller 33 further resets the count value C2 of the pressure counter 302 to atmospheric pressure Po. This process is an example of a reset process. After executing S211, the controller 33 executes S212.

[0075] As described above, the post-discharge pressure P1j is determined based on the discharge rates Q11,...Q1n. One condition for the post-discharge pressure P1j to be less than the pressure threshold T11 and for S211 to be executed is that each of the discharge rates Q11,...Q1n is greater than or equal to the amount corresponding to the pressure threshold T11 (for example, the first predetermined amount or the third predetermined amount) (for example, the first or fifth amount). On the other hand, one condition for the post-discharge pressure P1j to be greater than or equal to the pressure threshold T11 and for S211 to be skipped is that each of the discharge rates Q11,...Q1n is less than the pressure threshold T11 (for example, the second or sixth amount). Similarly, another condition for S211 to be executed is that each of the discharge rates Q21,...Q1n is relatively greater than the amount corresponding to the pressure threshold T12 (for example, the third amount). Another condition for skipping S211 is that each of the discharge rates Q11...Q1n is less than the pressure threshold T12 (an example of a fourth rate). Therefore, S210 is an example of a decision process.

[0076] In S212, the controller 33 moves the recording head 17 to the ejection start position in the left-right direction 9. The ejection start position is the initial position of the recording head 17 when recording one pass of images onto the sheet S supported by the platen 16.

[0077] As shown in Figure 8, during the process in which the recording head 17 moves from the home position to the discharge start position on the platen 16, the valve body 282 separates from the opening member 29 and closes the atmospheric communication hole 218E due to the biasing force of the compression coil spring 281. As a result, the atmospheric communication hole 218E becomes non-communicating. S212 is an example of a non-communicating process in which the state of the atmospheric communication hole 218E is changed to a non-communicating state by a switching mechanism.

[0078] In the ejection process of S213, the controller 33 transports the recording head 17 for one pass in the scanning direction (i.e., left-right direction 9) while ejecting ink of each color from the recording head 17. Specifically, while the recording head 17 is being transported at a constant speed in the left-right direction 9 above the platen 16, the controller 33 selectively applies voltage to the piezoelectric elements in the recording head 17 based on the ejection instruction information for the object to be processed. As a result, ink of the corresponding color is ejected from the nozzle rows 172A to 172D of the recording head 17. Consequently, one pass image is recorded in the unit recording area of ​​the sheet S.

[0079] The time it takes for the recording head 17 to travel one pass during the ejection process is an example of the first predetermined time or the third predetermined time. This travel time is a fixed value because the recording head 17 moves at a constant speed and the left and right lengths of each pass are the same when recording an image onto a single sheet S. The ejection process (S213) after the communication process (S211) is an example of the first ejection process. The ejection process performed without the communication process is an example of the second ejection process.

[0080] In S214, the controller 33 updates the count values ​​C11~C14, C2, and C3. Specifically, the controller 33 adds the discharge amount Q1j to the count value C11 of the discharge amount counter 301A. Similarly, the discharge amounts Q2j~Q4j are added to the count values ​​C12~C14. The controller 33 calculates the pressure change ΔP in the storage section 21 before and after the discharge of each color ink based on the discharge instruction information to be processed, using the following equations (1) and (2). In equation (1), the count values ​​C2 and C3 are the values ​​before the update. ΔP = -ΣQ × C² / (C³ + ΣQ) …(1) ΣQ = Q1j + Q2j + Q3j + Q4j …(2)

[0081] The controller 33 adds the pressure change ΔP to the count value C2 of the pressure counter 302. The controller 33 also adds ΣQ to the count value C3 of the air volume counter 303. As a result, the count value C2 indicates the current pressure in the storage unit 21, and the count value C3 indicates the current volume of air in the storage unit 21. This is the specific process of S214. S214 is an example of a pressure update process.

[0082] In S215, the controller 33 determines whether or not it has finished recording an image onto one sheet S. If the controller 33 determines that recording is not finished (No in S215), it executes S216. If the controller 33 determines that recording is finished (Yes in S215), it executes S217.

[0083] In S216, the controller 33 identifies the ejection instruction information for the next processing target in the RAM. The controller 33 then performs intermittent transport processing. In intermittent transport processing, the controller 33 rotates the PF motor 31 to transport the sheet S supported by the platen 16 in the transport direction (i.e., forward) for a distance corresponding to one pass in the transport direction, and then stops the rotation of the PF motor 31. After that, the controller 33 executes S208 shown in Figure 10(B).

[0084] In the discharge process of S217, the controller 33 rotates the transport roller pair 15 and the discharge roller pair 18 by controlling the PF motor 31, and discharges the sheet S from the discharge port 112 to the discharge tray 19.

[0085] In S218, the controller 33 determines whether or not all images have been recorded to sheet S. If the controller 33 determines that recording is not finished (No in S218), it executes S207 as shown in Figure 10(B). At this time, the recording head 17 is not moved to the home position. If the controller 33 determines that recording is finished (Yes in S218), it executes S219.

[0086] In the capping process in S219, the controller 33 moves the recording head 17 to the home position (see Figure 5) based on the output signal of the linear encoder 26, and then moves the cap 27 from the separated position to the capped position by controlling the lifting motor 32. As a result the atmospheric communication hole 218E becomes open, the controller 33 further resets the count value C2 of the pressure counter 302 to atmospheric pressure Po.

[0087] [Effects of image recording processing] In the image recording process of this embodiment, before the ejection process (S213 in Figure 11), the pressure between the storage unit 21 and the manifolds 177A to 177D is in equilibrium. This pressure is recorded in the EEPROM as the count value C2. During the ejection process, ink is ejected in a non-communicated state, so while the ejection process is being performed, the pressure in the manifolds 177A to 177D decreases by differential pressures DP1j, DP2j, DP3j, and DP4j compared to before the ejection process (see atmospheric pressure Po in Figure 12, for example). However, due to the high flow resistance of each of the manifolds 177A to 177D, ink is not quickly replenished from the storage unit 21 after ejection. That is, it takes some time to replenish the ink in the manifolds 177A to 177D. Also, during this process, the pressure in the manifolds 177A to 177D increases. Once ink replenishment is complete, the pressure in manifolds 177A to 177D (e.g., Po + ΔP) will equalize with the pressure in the reservoir 21. Note that in Figure 12, for convenience, the pressure thresholds T11 to T14 are set to be the same.

[0088] If a large amount of ink is ejected from the recording head 17 per unit time during the ejection process, a meniscus break due to under-refilling may occur. However, in this embodiment, before the ejection process, it is determined in S210 whether the second condition is met, that is, whether a meniscus break may occur if the ejection process is performed. If the second condition is met (Yes in S210), the ejection process (S213) is performed without the storage unit 21 being returned to atmospheric pressure Po by the communication process (S211), as shown in the time interval t11 in Figure 12. On the other hand, if the second condition is not met (No in S210), the ejection process (S213) is performed after the storage unit 21 is returned to atmospheric pressure Po by the communication process (S211), as shown from the time interval t11 onwards in Figure 12. Therefore, the pressure in the manifolds 177A to 177D is prevented from falling below the meniscus withstand pressure after the ejection process is performed, and as a result, a meniscus break due to under-refilling does not occur.

[0089] In this embodiment, as shown in Figures 10(B) and 11, after receiving a print job, the controller 33 opens the atmospheric communication hole 218E in S206 and then closes it in S212 before executing the ejection process (S213). This process is an example of an initialization process. This process causes the pressure inside the storage unit 21 to become atmospheric pressure Po before the ejection process, making it less likely for the post-ejection pressure P1j to be less than the pressure threshold T11, P2j to be less than the pressure threshold T12, P3j to be between T13 and the pressure threshold T13, or P4j to be less than the pressure threshold T14. As a result, the number of times S211 is executed in the image recording process is reduced.

[0090] In this embodiment, the post-discharge pressures P1j to P4j are calculated in step S209 of Figure 10. This eliminates the need for a pressure sensor to determine the post-discharge pressures P1j to P4j, thereby reducing the manufacturing cost of the printer 100.

[0091] [First variation] In this embodiment, the processing in S210-S212 was performed before each pass image was recorded on the sheet S. Such processing is particularly suitable for a serial-type printer 100 that performs image recording while intermittently transporting the sheet S. However, not limited to this embodiment, the printer 100 may perform this processing only before recording an image on each page of the sheet S. Specifically, in the first modified example, each of the ejection amounts Q11,...Q1n estimated in S201 is the amount of magenta ink ejected when recording an image for one page of a sheet (another example of a unit image area). The ejection amounts Q21,...Q2n, Q31,...Q3n, and Q41,...Q4n are the amounts of cyan, yellow, and black ink ejected when recording the same image. The processing in the first modified example is also applicable to a serial-type printer 100, but is particularly suitable for a line-type printer 100 that performs image recording without intermittently transporting the sheet S.

[0092] [Second variation] In this embodiment, the air chamber 219E was not partitioned by color. However, it is not limited to this, and as shown in Figure 13, the internal space 217A of the storage unit 21 may be partitioned by a transverse partition 221 and longitudinal partitions 222A to 222C, with corresponding air chambers 223A to 223D for each color directly above the storage chambers 219A to 219D (see Figure 7). In this case, each storage chamber 219A to 219D communicates individually with the outside of the storage unit 21 through individual atmospheric communication holes 224A to 224D. This configuration makes it difficult for multiple ink colors to mix within the storage unit 21. In addition, individual valve installation spaces 225A to 225D are provided to the right of each of the air chambers 223A to 223D, corresponding to each of the air chambers 223A to 223D. Furthermore, valve units 28A to 28D, having the same configuration as valve unit 28, are provided in each valve installation space 225A to 225D. Open members 29A to 29D, having the same configuration as open member 29, are provided on the side frame 114 to correspond to valve units 28A to 28D. Open members 29A to 29D collectively connect valve units 28A to 28D as the recording head 17 approaches the side frame 114 from the right, and collectively switch valve units 28A to 28D from connected to disconnected as the recording head 17 moves away from the side frame 114 to the right.

[0093] [Third variation] The image recording process according to the third modified example consists of the processes shown in S201-S209 (see Figure 10(B)) and Figure 14. Figure 14 differs from Figure 11 in that S301-S314 are executed instead of S211. The differences will be explained in detail below, while the common points will be omitted or simplified.

[0094] In S210 of Figure 14, the controller 33 determines that the second condition is not met (No in S210), and since a meniscus break due to under-refill may occur, it executes S301. The controller 33 determines that the second condition is met (Yes in S210), and executes S212 to S214. S213 is an example of the fifth discharge process.

[0095] In S301, the controller 33 divides the ejection instruction information to be processed in S208 into two passes and generates two divided ejection instruction pieces. Each of the two divided ejection instruction pieces is similar to the ejection instruction information in that it indicates the timing and amount of ink ejected from nozzles 173A to 173D while the recording head 17 moves for one pass. However, the two divided ejection instruction pieces differ from the ejection instruction information in that the recording head 17 moves for two passes (i.e., twice) over the same unit recording area to record the one-pass image indicated by the ejection instruction information. In short, the recording head 17 records the one-pass image by moving twice. Therefore, the time required to record the one-pass image in S313, described later, is longer than the time required to record the one-pass image by moving the recording head 17 once in S213.

[0096] Below are two specific examples of two types of split ejection instruction information. In the first example, one type of split ejection instruction information indicates that the left half of the 1-pass image will be recorded by the first movement of the recording head 17, and the other type of split ejection instruction information indicates that the right half of the same 1-pass image will be recorded by the second movement of the recording head 17. In the second example, one type of split ejection instruction information indicates that a portion of the 1-pass image will be recorded with a gap in the left-right direction 9 by the first movement of the recording head 17, and the other type of split ejection instruction information indicates that the remaining portion of the same 1-pass image will be recorded with a gap in the left-right direction 9 by the second movement of the recording head 17.

[0097] In S302, the controller 33 counts the amount of magenta ink ejected Q61 when recording a portion of the one-pass image based on one of the two split ejection instruction pieces generated in S301. The controller 33 further counts the amount of magenta ink ejected Q62 when recording the remaining portion of the same one-pass image based on the other split ejection instruction piece. Similarly, the ejection amounts of cyan ink Q71, Q72, yellow ink Q81, Q82, and black ink Q91, Q92 are also counted.

[0098] In S303, the controller 33 determines the differential pressures DP61, DP62, DP71, DP72, DP81, DP82, DP91, and DP92. DP61 = Q61 × R1, DP62 = Q62 × R1, DP71 = Q71 × R2, DP72 = Q72 × R2, DP81 = Q81 × R3, DP82 = Q82 × R3, DP91 = Q91 × R4, and DP92 = Q92 × R4.

[0099] In S304, the controller 33 obtains count values ​​C11 to C14 from the discharge volume counters 301A to 301D, the count value C2 from the pressure counter 302, and the count value C3 from the air volume counter 303. The controller 33 then calculates the post-discharge pressures P61, P71, P81, and P91. P61 = C2 + DP61, P71 = C2 + DP71, P81 = C2 + DP81, and P91 = C2 + DP91.

[0100] In S305, the controller 33 calculates the pressure change ΔP1 in the storage section 21 before and after the discharge of magenta ink with discharge volume Q61, cyan ink with discharge volume Q71, yellow ink with discharge volume Q81, and black ink with discharge volume Q91, using the following equations (3) and (4). In equation (3), the count values ​​C2 and C3 are the values ​​before the update. ΔP1=-ΣQ1×C2 / (C3+ΣQ1) …(3) ΣQ1 = Q61 + Q71 + Q81 + Q91 …(4)

[0101] In S306, the controller 33 calculates the post-discharge pressures P62, P72, P82, and P92. P62 = C2 + ΔP1 + DP61, P72 = C2 + ΔP1 + DP71, P82 = C2 + ΔP1 + DP81, and P92 = C2 + ΔP1 + DP92.

[0102] In S307, the controller 33 determines whether the third condition is met. The third condition is that the post-discharge pressures P61 and P62 are each at or above the pressure threshold T11, the post-discharge pressures P71 and P72 are each at or above the pressure threshold T12, the post-discharge pressures P81 and P82 are each at or above the pressure threshold T13, and the post-discharge pressures P91 and P92 are each at or above the pressure threshold T14. If the controller 33 determines that the third condition is not met (No in S307), it executes S308 because a meniscus break due to under-refill may occur. If the controller 33 determines that the third condition is met (Yes in S307), it executes S312.

[0103] In the communication process of S308, the controller 33 opens the atmospheric communication hole 218E using the opening member 29 in the same manner as in S206. As a result, the pressure inside the storage section 21 returns to atmospheric pressure Po, so that even if each color ink is ejected based on the respective dispensing instruction information, meniscus break due to under-refill does not occur. The controller 33 further resets the count value C2 of the pressure counter 302 to atmospheric pressure Po. After executing S308, the controller 33 executes S309.

[0104] In S309, since the pressure inside the storage unit 21 has returned to atmospheric pressure Po, the divided discharge instruction information is not necessary. Therefore, the controller 33 executes S309 to S311 in the same way as S212 to S214.

[0105] In S312, the controller 33 executes S312, which is similar to S212, and then executes S313.

[0106] In the ejection process of S313, the controller 33 moves the recording head 17 back and forth for two passes in the scanning direction, and while the recording head 17 is being transported at a constant speed in the left-right direction 9 above the platen 16, it ejects ink of the corresponding color from nozzle rows 172A to 172D based on the divided ejection instruction information for the two passes. As a result, one pass image is recorded in the unit recording area of ​​the sheet S. S313 is an example of a third or fourth ejection process.

[0107] In S314, the controller 33 updates the count values ​​C11~C14, C2, and C3. The discharge amounts Q1j~Q4j (see S208) are added to the count values ​​C11~C14, similar to S214. The controller 33 calculates the pressure change ΔP2 in the storage section 21 before and after the discharge of magenta ink with a discharge amount Q62, cyan ink with a discharge amount Q72, yellow ink with a discharge amount Q82, and black ink with a discharge amount Q92 using the following equations (5) and (6). In equation (5) as well, the count values ​​C2 and C3 are the values ​​before the update. ΔP2={-ΣQ2×C2-(ΣQ1+ΣQ2)×ΔP1} / (C3+ΣQ2) …(3) ΣQ2 = Q62 + Q72 + Q82 + Q92 …(4)

[0108] The controller 33 adds the pressure change ΔP2 to the count value C2 of the pressure counter 302. The controller 33 also adds ΣQ1 and ΣQ2 to the count value C3 of the air volume counter 303. As a result, the count value C2 indicates the current pressure in the storage unit 21, and the count value C3 indicates the current volume of air in the storage unit 21. This is the specific process of S314.

[0109] After executing S214, S311, and S314, the controller 33 executes S215 to S219 (see Figure 11).

[0110] In the third variation, as shown in the time interval t12 of Figure 15, if the amount of ejected ink Q1j to Q4j is so large that it does not satisfy the second condition (corresponding to the fifth amount), the ejected ink Q1j is divided into ejected ink Q61 and Q62. The ejected ink Q2j, Q3j, and Q4j are divided into two: ejected ink Q71 and Q72, ejected ink Q81 and Q82, and ejected ink Q91 and Q92. Therefore, the amount of ejected ink Q61, Q62, Q71, Q72, Q81, Q82, Q91, and Q92 may become small enough to satisfy the third condition. In such cases, the controller 33 ejects the ink of ejected ink Q1j to Q4j over the time it takes for the recording head 17 to move two passes due to the ejection process in S313 (i.e., time interval t12). In time interval t12, the ink ejection amounts Q61, Q62, etc., ejected by the recording head 17 during each of the two passes are small enough to satisfy the second condition (corresponding to the fifth amount). Note that time interval t12 is an example of the second predetermined time and the fourth predetermined time. As a result, by ejecting ink with ejection amounts Q1j to Q4j that do not satisfy the second condition over a long period of time, meniscus break due to under-refill is prevented even if ejection is performed without executing the communication process in S308. In other words, the frequency of executing the communication process is reduced.

[0111] [Fourth variation] The image recording process according to the fourth modified example consists of the processes shown in S201 to S209 (see Figure 10(B)) and Figure 16. Figure 16 differs from Figure 11 in that S401 and S402 are executed instead of S210. The differences will be explained in detail below, while the common points will be omitted or simplified.

[0112] The controller 33 stores a discharge rate threshold table, as shown in Figure 17, in an EEPROM or the like. The discharge rate threshold table records sets of discharge rate thresholds T41 to T44 for each numerical range of the count value C2 (i.e., the pressure before discharge). Each of the discharge rate thresholds T41 to T44 has a larger value as the count value C2 gets closer to atmospheric pressure Po.

[0113] As shown in Figure 16, in S401, the controller 33 obtains the discharge rate thresholds T41 to T44 corresponding to the count value C2 obtained in S209 of Figure 10(B) from the discharge rate threshold table.

[0114] In S402, the controller 33 determines whether the discharge rates Q1j to Q4j identified in S208 satisfy the fourth condition. The fourth condition is that the discharge rate Q1j is less than or equal to the discharge rate threshold T41 obtained in S401, the discharge rate Q2j is less than or equal to the discharge rate threshold T42 obtained in S401, the discharge rate Q3j is less than or equal to the discharge rate threshold T43 obtained in S401, and the discharge rate Q4j is less than or equal to the discharge rate threshold T44 obtained in S401. If the controller determines that the fourth condition is not satisfied (No in S402), the controller 33 executes S211. If the controller determines that the fourth condition is satisfied (Yes in S402), the controller 33 executes S212.

[0115] [Other variations] In this embodiment, the storage unit 21 was a so-called on-carriage type ink tank. However, it is not limited to this, and the storage unit 21 may be a so-called off-carriage type ink tank, that is, an ink tank located away from the carriage 24. Alternatively, the storage unit 21 may be an ink cartridge.

[0116] In this embodiment, the printer 100 was capable of recording full-color images onto the sheet S. However, it is not limited to this, and the printer 100 may also be capable of recording only monochrome images onto the sheet S.

[0117] In this embodiment, the switching mechanism was a combination of a transport mechanism 25 and an opening member 29. However, it is not limited to this, and the switching mechanism may be a solenoid valve that can open and close the atmospheric communication hole 218E under the control of a controller 33. In this case, the printer 100 may be equipped with a so-called line-type recording head 17.

[0118] In this embodiment, the storage section 21 was connected to the outside by an atmospheric communication hole 218E. However, the storage section 21 is not limited to this, and instead of the atmospheric communication hole 218E, the internal space of the storage section 21 may be connected to the outside by a labyrinth channel.

[0119] In the embodiment, the printer 100 was an example of an image recording device. However, the image recording process described in the embodiment and each modified example may be performed not only on the printer 100, but also on a multifunction device, copier, or fax machine. A multifunction device is a device that has multiple functions among printing, copying, and fax transmission / reception functions.

[0120] In this embodiment, the pressure in the storage section 21 was determined by calculation. However, the pressure in the storage section 21 may also be determined by a sensor.

[0121] In this embodiment, the printer 100 received a print job containing ejection instruction information for each pass from the information processing device. However, the invention is not limited to this; the information processing device may send a print job containing multiple pass data to the printer 100, and the printer 100 may generate ejection instruction information from each pass data included in the print job and then perform image recording processing. [Explanation of Symbols]

[0122] 100...Printer (an example of an image recording device) 15. Conveyor roller pair (an example of a conveying mechanism) 17. Recording head (an example of a head) 172A~172D...Nozzle row (Example of multiple nozzles, another example of multiple nozzles) 177A~177D... Manifold (Example of a liquid flow path) 18. Discharge roller pair (an example of a conveying mechanism) 21. Storage section 218E... Atmospheric communication port (an example of an atmospheric communication passage) 24...carriage 25. Conveying mechanism 28, 28A~28D... Valve Unit 29, 29A~29D... Open members 33. Controller

Claims

1. A head having multiple nozzles, A storage unit having a liquid storage chamber and an atmospheric communication passage connecting the storage chamber to the outside, A liquid flow path connects the above-mentioned storage chamber and the above-mentioned plurality of nozzles so that liquid can flow through it, A switching mechanism that switches the state of the above-mentioned atmospheric communication passage between a connected state in which the storage chamber is in communication with the outside and a disconnected state in which the storage chamber is not in communication with the outside, It is equipped with a controller, The above controller is The above switching mechanism performs a connection process that first connects the air passage that is currently disconnected, and then returns it to the disconnected state. A discharge process in which liquid is discharged from the above-mentioned plurality of nozzles within a predetermined time, An acquisition process to acquire the pre-discharge pressure, which is the pressure in the storage chamber before the execution of the above communication process and the above discharge process, A quantity calculation process that calculates the amount of liquid discharged from the plurality of nozzles within the first predetermined time period based on the image data of a unit image region, Based on the discharge volume calculated by the above volume calculation process and the pre-discharge pressure obtained by the above acquisition process, a pressure calculation process is performed to calculate the post-discharge pressure, which is the pressure in the liquid flow path after the liquid of the discharge volume has been discharged from the multiple nozzles. If the discharge pressure calculated by the above pressure calculation process reaches the threshold, the above communication process is executed, followed by the discharge process. An image recording device that, in accordance with the fact that the post-discharge pressure calculated by the above pressure calculation process has not reached a threshold, executes the above discharge process without executing the above communication process.

2. The image recording device according to claim 1, wherein the controller, in the pressure calculation process, calculates the amount of pressure change in the liquid flow path before and after the discharge of the liquid based on the discharge amount calculated by the amount calculation process and the resistance value of the liquid flow path, and calculates the post-discharge pressure based on the calculated amount of pressure change and the pre-discharge pressure acquired by the acquisition process.

3. A conveying mechanism that transports the sheet in the direction of transport, The above-mentioned head is mounted on a carriage that moves in a scanning direction intersecting the above-mentioned transport direction, The image data for the above unit image region is the image data for one pass in the above scanning direction. The image recording apparatus according to claim 1, wherein the controller determines the discharge amount in the amount calculation process based on image data for one pass in the scanning direction.

4. It is further equipped with a conveying mechanism that transports the sheet in the direction of transport, The image data for the above unit image region is the image data for one page of the above sheet. The image recording device according to claim 1, wherein the controller determines the discharge amount in the quantity calculation process based on the image data for one page of the sheet.

5. The above head further comprises several other nozzles, which are different from the above multiple nozzles. The above storage unit further includes other storage chambers different from the above storage chamber. The above-mentioned atmospheric passage further connects the above-mentioned other storage chamber to the outside of the above-mentioned other storage chamber. The above image recording device further comprises other liquid channels that connect the above-mentioned other storage chambers and the above-mentioned other plurality of nozzles in a manner that allows liquid to flow through them. In the above connected state, the other storage chambers are further connected to the outside, and in the above non-connected state, the other storage chambers are not further connected to the outside. The above controller is In the acquisition process described above, the pre-discharge pressure, which is the pressure in the storage chamber before the execution of the communication process and the discharge process described above, and the other pre-discharge pressure, which is the pressure in the other storage chamber, are acquired. In the above quantity calculation process, based on the image data of the unit image region, the amount of liquid discharged from the multiple nozzles and the other amount of liquid discharged from the other multiple nozzles within the first predetermined time are calculated. Based on the discharge volume and other discharge volumes calculated by the above volume calculation process, and the pre-discharge pressure and other pre-discharge pressures obtained by the above acquisition process, the post-discharge pressure, which is the pressure in the liquid flow path after the liquid of the said discharge volume has been discharged from the multiple nozzles, and the other post-discharge pressure, which is the pressure in the other liquid flow after the liquid of the other discharge volume has been discharged from the other multiple nozzles, are calculated. Depending on whether the post-discharge pressure calculated by the above pressure calculation process has reached a threshold, or whether other post-discharge pressures calculated by the above pressure calculation process have reached other thresholds, the above communication process is executed, followed by the discharge process. The image recording device according to claim 1, wherein the discharge process is executed without performing the communication process, in accordance with the fact that the discharge pressure calculated by the above pressure calculation process has not reached a threshold, and other discharge pressures calculated by the above pressure calculation process have not reached a threshold.

6. The above head further comprises several other nozzles, which are different from the above multiple nozzles. The above storage unit further comprises another storage chamber different from the above storage chamber, and another atmospheric communication passage connecting the other storage chamber to the outside. The above image recording device further comprises other liquid channels that connect the above-mentioned other storage chambers and the above-mentioned other plurality of nozzles in a manner that allows liquid to flow through them. The above switching mechanism controls the state of the other atmospheric communication passage so that when it is in the communication state, the other storage chamber is in communication with the outside, and when it is not in the non-communication state, the other storage chamber is not in communication with the outside. The above controller is In the acquisition process described above, the pre-discharge pressure, which is the pressure in the storage chamber before the execution of the communication process and the discharge process described above, and the other pre-discharge pressure, which is the pressure in the other storage chamber, are acquired. In the above quantity calculation process, based on the image data of the unit image region, the amount of liquid discharged from the multiple nozzles and the other amount of liquid discharged from the other multiple nozzles within the first predetermined time are calculated. Based on the discharge volume and other discharge volumes calculated by the above volume calculation process, and the pre-discharge pressure and other pre-discharge pressures obtained by the above acquisition process, the post-discharge pressure, which is the pressure in the liquid flow path after the liquid of the said discharge volume has been discharged from the multiple nozzles, and the other post-discharge pressure, which is the pressure in the other liquid flow after the liquid of the other discharge volume has been discharged from the other multiple nozzles, are calculated. Depending on whether the discharge pressure calculated by the above pressure calculation process has reached a threshold, or whether the other discharge pressures calculated by the above pressure calculation process have reached other thresholds, the above communication process further uses the above switching mechanism to connect the other air communication passages that were previously in a disconnected state, then disconnects them again, and then the above discharge process further discharges liquid from the other multiple nozzles within the first predetermined time. The image recording device according to claim 1, wherein, in accordance with the fact that the post-discharge pressure calculated by the above pressure calculation process has not reached a threshold, and that the other post-discharge pressures calculated by the above pressure calculation process have not reached a threshold, the discharge process further discharges liquid from the other nozzles within the first predetermined time without performing the above communication process.

7. The above controller is The image recording device according to claim 1, further performing an initialization process to return the atmospheric communication passage to the connected state and then to the disconnected state using the switching mechanism in response to receiving the above image data.

8. The above controller is In the above pressure calculation process, based on the discharge volume calculated by the above volume calculation process and the pre-discharge pressure obtained by the above acquisition process, a second post-discharge pressure is calculated, which is the pressure in the liquid flow path after the liquid of the discharge volume has been discharged from the plurality of nozzles within a second predetermined time that is longer than the first predetermined time. The image recording device according to claim 1, wherein, in accordance with the fact that the post-discharge pressure calculated by the above pressure calculation process has reached a threshold and the second post-discharge pressure has not reached the threshold, a second discharge process is performed to discharge the above discharge amount of liquid from the plurality of nozzles within the second predetermined time without performing the above communication process.

9. The system further includes a memory for storing the above-mentioned pre-discharge pressure, The above controller is In response to the execution of the above discharge process, a pressure update process is further executed, which updates the pre-discharge pressure stored in the memory with the post-discharge pressure. The image recording device according to claim 1, wherein the pressure calculation process determines the post-discharge pressure based on the discharge amount calculated by the quantity calculation process and the pre-discharge pressure stored in the memory.

10. The image recording device according to claim 9, further comprising: a reset process that resets the pre-discharge pressure stored in the memory in accordance with the state of the atmospheric communication passage being set to the communication state.

Images