Inkjet recording apparatus

Abstract

To recover ink discharged from a line head during flushing, and to maintain the recovery efficiency of the ink without requiring cleaning or replacement even if the recovery amount of the ink increases.SOLUTION: The controller 66 in the inkjet recording device 10 includes the line heads 15B to 15Y configured to eject ink droplets, the conveyance belt 6 configured to convey a recording sheet to which the ink droplets ejected from the line heads are applied and having the opening holes 38 through which the ejected ink droplets pass, the ink collection section 32 disposed to face the line heads via the conveyance belt 6 and configured to receive and collect the ink droplets having passed through the opening holes 38, and the drawing fan 44 configured to generate an airflow for moving the ink droplets inside the ink collection section 32.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an inkjet recording apparatus that ejects ink from a line head onto recording paper to form an image on the recording paper, and more particularly to a technique for recovering ink ejected from the line head during flushing. [Background technology]

[0002] Inkjet recording devices can sometimes have problems ejecting ink from the nozzles of a line head due to an increase in the viscosity of the ink, so flushing is performed to eject ink from the nozzles to prevent ink ejection problems. During this flushing, it is necessary to collect the ink ejected from the line head.

[0003] In addition, in the inkjet recording device described in Patent Document 1, the recording head and encoder are mounted on a carriage that moves in the width direction of the recording paper, and the position of the carriage is determined based on information such as the pattern on an encoder film read by the carriage's encoder. Furthermore, since ink mist is generated when ink droplets are ejected from the recording head, the degree of contamination of the encoder film due to ink mist is determined based on the S / N ratio of the output signal from the encoder sensor. When the encoder film becomes contaminated, the rotation speed of the mist recovery fan that recovers the ink mist is increased, thereby improving the mist recovery efficiency. This prevents the ink mist from affecting the recording results. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-107230 Summary of the Invention [Problem to be solved by the invention]

[0005] Here, when recovering ink ejected from the line head during flushing as described above, it is desirable to maintain the ink recovery efficiency even if the amount of recovered ink increases.

[0006] In Patent Document 1, ink mist is collected, but the ink ejected from the line head during flushing is not collected. Also, since the method determines whether the encoder film is contaminated by ink mist, maintenance such as cleaning or replacing the encoder film is required.

[0007] Therefore, the present invention has been made in consideration of the above circumstances, and aims to recover ink ejected from a line head during flushing, and maintain ink recovery efficiency even if the amount of recovered ink increases, without requiring cleaning or replacement. [Means for solving the problem]

[0008] An inkjet recording device according to one aspect of the present invention comprises a line head that ejects ink droplets; a conveyor belt that conveys recording paper onto which the ink droplets ejected from the line head are applied and has openings through which the ejected ink droplets pass; an ink recovery unit that is arranged opposite the line head via the conveyor belt and receives and recovers the ink droplets that have passed through the openings; an air flow generating unit that generates an air flow inside the ink recovery unit to move the ink droplets; and a control unit that determines the amount of ink droplets recovered by the ink recovery unit, and when the amount of ink droplets recovered by the ink recovery unit becomes equal to or greater than a predetermined threshold, controls the air flow generating unit to promote the generation of an air flow by the air flow generating unit. [Effects of the Invention]

[0009] According to the present invention, ink ejected from the line head during flushing is recovered, and even if the amount of recovered ink increases, cleaning or replacement is not required and ink recovery efficiency can be maintained. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing an inkjet recording apparatus according to an embodiment of the present invention. [Figure 2] 2A and 2B are side views schematically showing a conveying belt, each line head, each suction unit, each ink recovery unit, etc. in the inkjet recording apparatus of the present embodiment. [Figure 3] 2A and 2B are plan views schematically showing a conveying belt, each line head, each suction unit, each ink recovery unit, and the like in the inkjet recording apparatus of the present embodiment. [Figure 4] FIG. 2 is a perspective view showing the appearance of an ink recovery unit. [Figure 5] FIG. 2 is a perspective view showing a plurality of layers of porous members and a plate member housed in the ink recovery unit. [Figure 6] 1 is a block diagram showing the internal configuration of an inkjet printing apparatus according to an embodiment of the present invention; [Figure 7] 10 is a flowchart showing a control procedure for determining the amount of ink droplets collected by the ink collection unit, and increasing the rotation speed of the suction fan of the ink collection unit when the amount of ink droplets collected becomes equal to or greater than a threshold value. DETAILED DESCRIPTION OF THE INVENTION

[0011] An inkjet recording apparatus according to one embodiment of the present invention will be described below. Fig. 1 is a cross-sectional view showing an inkjet recording apparatus according to one embodiment of the present invention. As shown in Fig. 1, an inkjet recording apparatus 10 includes an image reading unit 11 and an image forming unit 12.

[0012] The image reading unit 11 has, for example, a contact image sensor (CIS) as an imaging element that optically reads the image of the original M. When a plurality of originals M are placed on the original tray 1, the image of each original M is read by the imaging element while these originals M are successively pulled out from the original tray 1 and conveyed, and each original M is successively discharged and stacked on the discharge tray 2. For each image of each original M, the output of the imaging element is converted into image data that indicates the image of the original M.

[0013] Image forming unit 12 receives image data representing an image of original M and forms the image of original M represented by the image data on recording paper P by an inkjet method. Image forming unit 12 has line heads 15B, 15C, 15M, and 15Y that eject ink droplets of four colors (black, cyan, magenta, and yellow). Each line head 15B, 15C, 15M, and 15Y ejects and applies ink droplets of the corresponding color onto recording paper P that has been transported from paper feed unit 14 through transport path 3 to transport unit 4, thereby forming a color image on recording paper P.

[0014] The transport unit 4 includes a drive roller 8, a driven roller 9, a tension roller 5, and a transport belt 6. The transport belt 6 is an endless belt that is stretched over the drive roller 8, the driven roller 9, and the tension roller 5. The drive roller 8 is a roller that is driven to rotate counterclockwise by a motor (e.g., a stepping motor), and as the drive roller 8 is driven to rotate, the transport belt 6 moves in a counterclockwise direction, and the driven roller 9 and the tension roller 5 are driven to rotate counterclockwise. The tension roller 5 is a roller that maintains an appropriate tension on the transport belt 6.

[0015] After the image of the document is formed on the recording paper P by the image forming unit 12, the recording paper P passes through a conveying path 18 and is discharged onto a discharge tray 17 via a conveying roller 19.

[0016] Meanwhile, a plurality of suction units 31 and a plurality of ink recovery units 32 are arranged between the drive roller 8 and driven roller 9 and between the vertically stretched conveyor belt 6. Each suction unit 31 sucks air through a large number of air holes formed in the conveyor belt 6, and adsorbs the recording paper P to the conveyor belt 6 by negative pressure, maintaining the recording paper P in a flat state.

[0017] Each ink recovery unit 32 is disposed at a position facing each line head 15B, 15C, 15M, and 15Y across the conveyor belt 6. A plurality of openings are formed in the conveyor belt 6. With each opening of the conveyor belt 6 moved between the line head and the ink recovery unit 32 as the conveyor belt 6 rotates, ink droplets ejected from the line head pass through each opening of the conveyor belt 6 and are recovered by the ink recovery unit 32 disposed opposite the line head.

[0018] 2 and 3 are plan and side views schematically showing the conveyor belt 6, each of the line heads 15B, 15C, 15M, and 15Y, each suction unit 31, and each of the ink recovery units 32. As shown in FIGS. 2 and 3, each of the line heads 15B, 15C, 15M, and 15Y is configured by combining three head units 151. The head units 151 are arranged, for example, along the width direction of the recording paper, which is perpendicular to the conveyance direction A of the recording paper, and adjacent head units 151 in the width direction are staggered in the conveyance direction A, that is, arranged in a so-called staggered pattern.

[0019] Each head unit 151 has a plurality of nozzles 33 that eject ink, and the lower end of each nozzle 33 is positioned at a fixed interval (for example, 1 mm) from the upper surface of the conveyor belt 6. Ink droplets are ejected from each nozzle 33 by a known piezoelectric method using a piezoelectric element, or by a known thermal method using a heater, and ink droplets are ejected from the nozzles 33 by either method.

[0020] Black ink droplets are ejected from the nozzles 33 of each head portion 151 of line head 15B onto the recording paper on the transport belt 6, cyan ink droplets are ejected from the nozzles 33 of each head portion 151 of line head 15C onto the recording paper on the transport belt 6, magenta ink droplets are ejected from the nozzles 33 of each head portion 151 of line head 15M onto the recording paper on the transport belt 6, and yellow ink droplets are ejected from the nozzles 33 of each head portion 151 of line head 15Y onto the recording paper on the transport belt 6. In this way, ink of each color is applied to the recording paper, and a color image is formed on the recording paper.

[0021] The conveyor belt 6 is formed with a large number of vent holes through which the air sucked by each suction section 31 passes as described above. The recording paper P on the conveyor belt 6 is attracted to the conveyor belt 6 by the negative pressure generated by the suction of air through each vent hole, and is flattened.

[0022] Furthermore, a plurality of flushing areas 37 extending in the width direction of the recording paper are set on the conveyor belt 6, and a plurality of openings 38 through which ink droplets ejected from each of the line heads 15B, 15C, 15M, and 15Y pass as described above are formed in each of the flushing areas 37. When the flushing area 37 moves between the line head and the ink recovery unit 32 as the conveyor belt 6 rotates, ink droplets are ejected from that line head, pass through each opening 38 of the flushing area 37, and are recovered by the ink recovery unit 32 arranged opposite the line head.

[0023] The width of each flushing area 37 is wider than the width of each line head 15B, 15C, 15M, and 15Y, so that all ink droplets ejected from each line head 15B, 15C, 15M, and 15Y pass through each opening 38 of the flushing area 37. Here, the shape of each opening 38 is circular, but is not limited to circular, and may be elliptical, rectangular, or the like.

[0024] This ejection of ink droplets for collection in the ink recovery unit 32 is called flushing. Since an increase in the viscosity of ink in the nozzles of the line head can cause problems with ink ejection from the nozzles, the ink droplets are ejected by flushing and then collected in the ink recovery unit 32 to avoid such problems.

[0025] Each ink recovery unit 32 is detachably provided so that it can be replaced with a new one when it becomes full of recovered ink.

[0026] 2, a belt sensor 35 and a paper sensor 36 are provided above the conveyor belt 6 where the recording paper P is conveyed. The belt sensor 35 is, for example, an optical sensor, and detects a reference position mark (not shown) marked in one place on the conveyor belt 6. The paper sensor 36 is, for example, an optical sensor, and detects the leading and trailing edges of the recording paper P being conveyed by the conveyor belt 6.

[0027] Fig. 4 is a perspective view showing the appearance of the ink recovery unit 32. As shown in Fig. 4, the ink recovery unit 32 includes a rectangular parallelepiped main body housing 41, a cover 42 that closes the upper opening of the main body housing 41, a duct 43 provided at the opening at the bottom of the main body housing 41, and a suction fan 44 provided at one end of the duct 43.

[0028] Three rectangular openings 42A are formed in the lid body 42. For each of the line heads 15B, 15C, 15M, and 15Y, the ink recovery unit 32 is disposed opposite the line head via the conveyor belt 6, and the three head units 151 of the line head face the three rectangular openings 42A of the lid body 42, respectively. Therefore, when the flushing region 37 of the conveyor belt 6 moves between the line head and the ink recovery unit 32 as the conveyor belt 6 rotates, at least one head unit 151 of the line head faces the rectangular opening 42A of the lid body 42 through each opening 38 of the flushing region 37, and ink droplets ejected from that head unit 151 pass through each opening 38 of the flushing region 37, enter the rectangular opening 42A of the lid body 42, and are collected.

[0029] A part of the bottom of the main body housing 41 is opened, and a duct 43 is provided in this opening, and the other part of the bottom of the main body housing 41 is closed.

[0030] When suction fan 44 provided at one end of duct 43 is rotated, suction fan 44 sucks in air from inside duct 43 and exhausts it to the outside, generating an airflow that flows from the inside of main body housing 41 through duct 43 to suction fan 44, and at the same time, generating an airflow that flows from each rectangular opening 42A of lid 42 into the inside of main body housing 41. Therefore, the air flows through each rectangular opening 42A of lid 42 → inside main body housing 41 → duct 43 → suction fan 44, and is exhausted to the outside.

[0031] FIG. 5 is a perspective view showing the internal structure of the ink recovery unit 32. As shown in FIG. 5, a first-layer porous member 51, a second-layer plate member 52, a third-layer porous member 53, a fourth-layer plate member 54, and a fifth-layer porous member 55 are housed inside the main body housing 41 of the ink recovery unit 32, stacked in this order from bottom to top. The first-layer porous member 51, the third-layer porous member 53, and the fifth-layer porous member 55 are open-cell porous members that absorb and retain ink droplets, and are made of foamed resin materials such as melamine sponge and urethane foam. The first-layer porous member 51, the third-layer porous member 53, and the fifth-layer porous member 55 are each formed with air paths 51A, 53A, and 55A that guide air through them.

[0032] Air passage holes 52A, 54A for passing air are formed in the second layer plate member 52 and the fourth layer plate member 54, respectively. The air passage hole 52A in the second layer plate member 52 overlaps with the air path 51A in the first layer porous member 51 and the air path 53A in the third layer porous member 53, and the air passage hole 54A in the fourth layer plate member 54 overlaps with the air path 53A in the third layer porous member 53 and the air path 55A in the fifth layer porous member 55. Therefore, air flows from the air path 55A in the fifth layer porous member 55 through the air passage hole 52A in the second layer plate member 52 to the air path 53A in the third layer porous member 53, and air flows from the air path 53A in the third layer porous member 53 through the air passage hole 54A in the fourth layer plate member 54 to the air path 55A in the fifth layer porous member 55.

[0033] When the suction fan 44 is rotated as described above, air flows from each rectangular opening 42A of the lid 42 to the inside of the main housing 41 to the duct 43 to the suction fan 44, and is then exhausted to the outside. At this time, inside the main housing 41, the air flows from the air path 55A of the porous member 55 of the fifth layer to the air passage hole 54A of the plate member 54 of the fourth layer to the air path 53A of the porous member 53 of the third layer to the air passage hole 52A of the plate member 52 of the second layer to the air path 51A of the porous member 51 of the first layer. This results in a complex airflow path inside the main housing 41, and the air flows through each rectangular opening 42A of the lid 42, is agitated inside the main housing 41, and then flows to the duct 43.

[0034] For this reason, when the flushing area 37 of the conveyor belt 6 is moved between the line head and the ink recovery unit 32 as described above and ink droplets ejected from the head unit 151 of the line head pass through each opening 38 of the flushing area 37 and enter the rectangular opening 42A of the cover body 42, the ink droplets move with the flow of air stirred inside the main body housing 41 and come into contact with and are absorbed by the fifth layer porous member 55, the third layer porous member 53, or the first layer porous member 51, or the ink droplets become a mist due to the flow of air stirred inside the main body housing 41 and come into contact with and are absorbed by any of the porous members 55, 53, and 51. In this way, the ink droplets ejected from the line head are recovered in the ink recovery unit 32.

[0035] Fig. 6 is a block diagram showing the internal configuration of the inkjet recording apparatus 10. As shown in Fig. 6, the inkjet recording apparatus 10 includes an image reading unit 11, an image forming unit 12, a paper feed unit 14, an operation unit 61, a display unit 62, a touch panel 63, a storage unit 64, and a control unit 65. These components are capable of transmitting and receiving data or signals to and from each other via a bus.

[0036] The image forming unit 12 is provided with each line head 15B, 15C, 15M, 15Y, a motor (e.g., a stepping motor) 67 that rotates the drive roller 8 of the conveying belt 6, a belt sensor 35 that detects a reference position mark (not shown) printed at one point on the conveying belt 6, a paper sensor 36 that detects the leading and trailing ends of the recording paper P on the conveying belt 6, and suction fans 44 of each ink recovery unit 32.

[0037] The operation unit 61 has physical keys such as a numeric keypad, a decision key, a start key, etc. The display unit 62 is configured with a liquid crystal display (LCD) or an organic light-emitting diode (OLED) display.

[0038] A touch panel 63 is arranged on the screen of the display unit 62. The touch panel 63 is a so-called resistive or capacitive touch panel, and detects contact (touch) of a user's finger or the like with the touch panel 63 together with the contact position, and outputs a detection signal indicating the coordinates of the contact position to a control unit 66 of a control unit 65.

[0039] The storage unit 64 is a large-capacity storage device such as an SSD (Solid State Drive) or an HDD (Hard Disk Drive), and stores various application programs and various data.

[0040] Each RFID reader 68 is provided at the mounting location of each ink recovery unit 32, and reads the amount K of ink recovered by flushing from the RFID tag (not shown) of each ink recovery unit 32. Each ink container 21 is provided with an RFID tag, and the amount K of ink recovered by the ink recovery unit 32 by flushing is stored in the RFID tag.

[0041] The control unit 65 is composed of a processor, a RAM (Random Access Memory), a ROM (Read Only Memory), etc. The processor is, for example, a CPU (Central Processing Unit), an ASIC, or an MPU (Micro Processing Unit), etc. The control unit 65 functions as a control unit 66 when a control program stored in the ROM or the storage unit 64 is executed by the processor.

[0042] The control unit 66 comprehensively controls the inkjet recording apparatus 10. The control unit 66 is connected to the image reading unit 11, the image forming unit 12, the paper feeding unit 14, the operation unit 61, the display unit 62, the touch panel 63, and the storage unit 64, and controls the operation of these components and transmits and receives signals or data to and from each of the components.

[0043] The control unit 66 serves as a processing unit that executes various processes required for image formation by the inkjet recording apparatus 10. The control unit 66 also accepts operation instructions input by the user based on detection signals output from the touch panel 63 or operation of the physical keys on the operation unit 61. For example, the control unit 66 accepts touch operations on a GUI (Graphical User Interface) displayed on the screen of the display unit 62 through the touch panel 63. Furthermore, the control unit 66 has a function of controlling the display operation of the display unit 62.

[0044] In addition, each line head 15B, 15C, 15M, and 15Y corresponds to the line head in the claims, the conveying belt 6 corresponds to the conveying belt in the claims, each ink recovery unit 32 corresponds to the ink recovery unit in the claims, the suction fan 44 of each ink recovery unit 32 corresponds to the air flow generating unit in the claims, and the control unit 66 corresponds to the control unit in the claims.

[0045] In the inkjet recording device 10 configured as described above, the control unit 66 drives and controls the motor 67 that rotates the drive roller 8 of the conveyor belt 6, causing the conveyor belt 6 to convey the recording paper P, while controlling each of the line heads 15B, 15C, 15M, and 15Y to eject ink droplets from each of the line heads 15B, 15C, 15M, and 15Y onto the recording paper P on the conveyor belt 6, forming a color image on the recording paper P, and also passing the ink droplets ejected from each of the line heads 15B, 15C, 15M, and 15Y through each of the opening holes 38 in the flushing area 37 of the conveyor belt 6 and recovering them in each of the ink recovery units 32.

[0046] Here, when a color image is formed on the recording paper P, the ejection of ink droplets from each of the line heads 15B, 15C, 15M, and 15Y begins at the timing when the leading edge of the recording paper P reaches each of the line heads 15B, 15C, 15M, and 15Y.

[0047] For example, the distance from the detection position of the leading edge of the recording paper P by the paper sensor 36 to each of the line heads 15B, 15C, 15M, and 15Y is known, and the transport distance of the recording paper P corresponds to the rotation angle of the motor 67 that rotates the drive roller 8 of the transport belt 6, so the rotation angle (amount of rotation) of the motor 67 required to transport the recording paper P by each distance from the detection position of the leading edge of the recording paper P is known.

[0048] The control unit 66 controls the motor 67 that rotates the drive roller 8 of the conveyor belt 6, causing the conveyor belt 6 to convey the recording paper P, and when the leading edge of the recording paper P is detected by the paper sensor 36, the control unit 66 determines the rotation angle of the motor 67 from the time the leading edge was detected, and sequentially determines the timing at which this determined rotation angle (amount of rotation) of the motor 67 reaches each rotation angle corresponding to each of the above-mentioned separation distances, that is, determines the respective timings at which the leading edge of the recording paper P reaches each of the line heads 15B, 15C, 15M, and 15Y, and at each timing, causes each of the line heads 15B, 15C, 15M, and 15Y to start ejecting ink droplets. As a result, ink droplets of each color are ejected and applied to the recording paper P, and a color image is formed on the recording paper P.

[0049] Furthermore, when the ink droplets ejected from each line head 15B, 15C, 15M, and 15Y are passed through each opening hole 38 of the flushing area 37 of the conveying belt 6 and collected by each ink recovery unit 32, the control unit 66 determines the positional relationship between the position of the recording paper P on the conveying belt 6 and each flushing area 37, selects a flushing area 37 of the conveying belt 6 that is not overlapping with the recording paper P based on each of the above-mentioned timings, and when the selected flushing area 37 moves and reaches between the line head and the ink recovery unit 32, causes that line head to eject ink droplets.

[0050] For example, since the positional relationship between the reference position mark of the conveyor belt 6 and each flushing area 37 of the conveyor belt 6 is known, when the belt sensor 35 detects the reference position mark of the conveyor belt 6, the control unit 66 knows the position of each flushing area 37 relative to the detected position of the reference position mark. When the conveyor belt 6 further rotates and the reference position mark moves from the detected position of the reference position mark, the control unit 66 detects the moved position of the reference position mark and the moved position of each flushing area 37 from the detected position of the reference position mark based on the rotation angle of the motor 67 that rotates the drive roller 8 of the conveyor belt 6. Furthermore, because the distances between the detection position of the reference position mark and each of the line heads 15B, 15C, 15M, and 15Y are known, the control unit 66 can determine the positional relationship between each flushing area 37 and each of the line heads 15B, 15C, 15M, and 15Y based on the movement position of each flushing area 37 from the detection position of the reference position mark and the distances therebetween, and can detect the respective timings at which the flushing area 37 moves and arrives between each of the line heads 15B, 15C, 15M, and 15Y and each of the ink recovery units 32 for each flushing area 37 on the conveyor belt 6. Furthermore, because the distances between the detection position of the reference position mark and the paper sensor 36 are known, the control unit 66 can determine the positions (leading and trailing edge positions) of the recording paper P relative to the reference position mark on the conveyor belt 6 based on the two movement positions of the reference position mark and the distances therebetween when the paper sensor 36 detects the leading and trailing edges of the recording paper P, respectively. Furthermore, since the control unit 66 knows the positional relationship between the reference position mark and each flushing area 37, it also knows the positional relationship between the position of the recording paper P on the conveyor belt 6 and each flushing area 37, and can detect flushing areas 37 of the conveyor belt 6 that do not overlap with the recording paper P. Therefore, the control unit 66 can detect the timing at which, as the conveyor belt 6 rotates, the flushing areas 37 of the conveyor belt 6 that do not overlap with the recording paper P move and arrive between each of the line heads 15B, 15C, 15M, 15Y and each of the ink recovery units 32.

[0051] The control unit 66 controls the motor 67 that rotates the drive roller 8 of the conveyor belt 6, and when the belt sensor 35 detects the reference position mark of the conveyor belt 6, determines the position of the reference position mark of the conveyor belt 6 and the position of each flushing area 37, and constantly determines and updates the movement position of the reference position mark of the conveyor belt 6 and the movement position of each flushing area 37 according to the rotation angle of the motor 67. After determining the movement position of each flushing area 37, the control unit 66 determines the positional relationship between each flushing area 37 and each line head 15B, 15C, 15M, and 15Y, and determines the timing when the flushing area 37 moves and reaches between each line head 15B, 15C, 15M, and 15Y and each ink recovery unit 32, for each flushing area 37.

[0052] In addition, when the leading and trailing ends of the recording paper P being transported by the conveying belt 6 are detected by the paper sensor 36, the control unit 66 determines the position of the recording paper P relative to the reference position mark on the conveying belt 6, determines the positional relationship between the position of the recording paper P on the conveying belt 6 and each flushing area 37, and selects a flushing area 37 on the conveying belt 6 that is not overlapping with the recording paper P.

[0053] Then, at the timing when the selected flushing region 37 moves between each of the line heads 15B, 15C, 15M, and 15Y and each of the ink recovery units 32, the control unit 66 causes ink droplets to be ejected by the line head that the selected flushing region 37 has reached. These ink droplets pass through each of the openings 38 of the selected flushing region 37 of the conveyor belt 6 and are recovered by the ink recovery unit 32 disposed opposite the line head.

[0054] Here, when ink droplets for flushing are ejected from the line head as described above and collected in the ink recovery unit 32, the collection efficiency may decrease if the amount of ink droplets collected in the ink recovery unit 32 increases. For example, the first-layer porous member 51, the third-layer porous member 53, and the fifth-layer porous member 55 in the ink recovery unit 32 expand due to the absorption of ink, narrowing their air paths 51A, 53A, and 55A, or narrowing the air passage hole 52A in the second-layer plate member 52 and the air passage hole 54A in the fourth-layer plate member 54 due to the adhesion of ink, etc., resulting in a decrease in the flow rate and flow velocity of air inside the main body housing 41 of the ink recovery unit 32 and a decrease in the ink collection efficiency of the ink recovery unit 32.

[0055] Therefore, in this embodiment, the control unit 66 determines the amount of ink droplets collected by each ink recovery unit 32 for each ink recovery unit 32 arranged opposite each line head 15B, 15C, 15M, 15Y, and when the amount of ink droplets collected by the ink recovery unit 32 reaches or exceeds a preset threshold (for example, 50% of the limit amount of ink droplets that can be collected by the ink recovery unit 32), increases the rotation speed of the suction fan 44 of the ink recovery unit 32. This avoids a decrease in the flow rate and flow velocity of air inside the main body housing 41 of the ink recovery unit 32, and prevents a decrease in the efficiency of ink recovery by the ink recovery unit 32.

[0056] Next, the control procedure for determining the amount of ink droplets collected by the ink recovery unit 32 and increasing the rotation speed of the suction fan 44 of the ink recovery unit 32 when the amount of ink droplets collected is equal to or greater than a threshold will be described with reference to the flowchart shown in FIG.

[0057] During image formation operation, the control unit 66 drives and controls the motor 67 to move the conveyor belt 6 in a circular motion as described above, causing the conveyor belt 6 to transport the recording paper P, and causes each line head 15B, 15C, 15M, and 15Y to eject ink droplets onto the recording paper P on the conveyor belt 6, thereby forming a color image on the recording paper P (S101).

[0058] At this time, the control unit 66 sets the rotation speed of the suction fan 44 of each ink recovery unit 32 to a predetermined constant rotation speed (S102).

[0059] While the motor 67 is rotating the conveyor belt 6 to form an image, the control unit 66 constantly determines the movement position of the reference position mark on the conveyor belt 6 and the movement position of each flushing area 37, and determines the timing at which each flushing area 37 moves between and reaches a position between each line head 15B, 15C, 15M, and 15Y and each ink recovery unit 32. The control unit 66 determines the positional relationship between the position of the recording paper P on the conveyor belt 6 and each flushing area 37, and selects a flushing area 37 on the conveyor belt 6 that does not overlap with the recording paper P. Then, at the timing at which the selected flushing area 37 moves between and reaches a position between each line head 15B, 15C, 15M, and 15Y and each ink recovery unit 32, the control unit 66 ejects ink droplets from the line head that the selected flushing area 37 has reached, thereby performing flushing (S103). This executes flushing of each of the line heads 15B, 15C, 15M, and 15Y. At this time, since the suction fan 44 is driven at the above-mentioned constant rotation speed, the ink droplets are collected in the ink collection unit 32 by the suction fan 44.

[0060] In this state, the control unit 66 causes the RFID reader 68 to read the amount K of collected ink from the RFID tag of the ink recovery unit 32 for each ink recovery unit 32 (S104). Then, the control unit 66 calculates the ejection amount N of ink droplets ejected from the line head to the ink recovery unit 32 through each opening 38 of the flushing region 37 for each line head 15B, 15C, 15M, 15Y (S105), and adds this ejection amount N to the recovery amount K of that ink recovery unit 32 to update the recovery amount K of that ink recovery unit 32 (S106).

[0061] For example, if a fixed amount of ink droplets is ejected from the line head for each flushing, the control unit 66 determines the number of flushings as the amount of ink recovered by the ink recovery unit 32, K, and calculates the number of flushings performed between the line head and the ink recovery unit 32, "1", for each line head 15B, 15C, 15M, and 15Y as the amount of ink droplet ejection, N, and adds this ejection amount, N (= 1), to the amount of ink recovered by the ink recovery unit 32 up to that point, thereby updating the amount of ink recovered by the ink recovery unit 32.

[0062] In addition, when calculating the number of ink droplets ejected from the line head or the ejection period for each flushing, the control unit 66 sets the ink recovery amount K of the ink recovery unit 32 as the number of ink droplets ejected or the ejection period, and calculates the number of ink droplets ejected from the line head to the ink recovery unit 32 or the ejection period for each line head 15B, 15C, 15M, and 15Y as the ejection amount N, and adds this ejection amount N to the previous recovery amount K of the ink recovery unit 32 to update the recovery amount K of the ink recovery unit 32.

[0063] The control unit 66 causes the RFID reader 68 to write the recovery amount K updated in S106 to the RFID tag of the ink recovery unit 32 for each ink recovery unit 32 (S107), and determines whether the recovery amount K updated in S106 is equal to or greater than a preset threshold value S (S108). For example, if the ink recovery amount K of the ink recovery unit 32 corresponds to the number of flushings, the threshold value S is set to "50" in advance, and it is determined whether the ink recovery amount K updated in S106 is equal to or greater than the threshold value S (= 50).

[0064] If the recovered amount K is less than the threshold value S (S108 "No"), the control unit 66 maintains the rotation speed of the suction fan 44 of the ink recovery unit 32 that recovered this recovered amount K of ink at the constant rotation speed set in S102 (S109), and returns to processing from S103.

[0065] Furthermore, if the recovery amount K is equal to or greater than the threshold value S (S108 "Yes"), the control unit 66 increases the rotation speed of the suction fan 44 of the ink recovery unit 32 that recovered this recovery amount K of ink from the constant rotation speed set in S102 to a preset rotation speed (for example, a rotation speed that is 10 to 30% higher than the standard rotation speed during normal operation) (S110), and returns to the processing from S103. For example, if the motor of the suction fan 44 is PWM controlled, the control unit 66 increases the duty ratio of the pulse signal applied to the motor to increase the rotation speed of the suction fan 44.

[0066] At this time, if the recovery amount K updated in S106 is equal to or greater than the threshold value S, the control unit 66 may calculate the difference between the recovery amount K and the threshold value S, and the larger this difference becomes, the more it may increase the rotation speed of the suction fan 44. For example, if the control unit 66 corresponds the ink recovery amount K of the ink recovery unit 32 to the number of flushings and sets the threshold value S to "50," the control unit 66 increases the recovery amount K to "51," "52," ..., and the larger the difference between the recovery amount K and the threshold value S (= 50), the more it will increase the rotation speed of the suction fan 44.

[0067] Thereafter, similarly, at the timing when the flushing area 37 of the conveyor belt 6 that is not overlapping with the recording paper P moves and reaches between each of the line heads 15B, 15C, 15M, and 15Y and each of the ink recovery units 32, the control unit 66 causes the line head that has reached the selected flushing area 37 to eject ink droplets, and causes the RFID reader 68 to read the amount of recovered ink K from the RFID tag of each of the ink recovery units 32. The control unit 66 also calculates, for each of the line heads 15B, 15C, 15M, and 15Y, the ejection amount N of ink droplets ejected from the line head through each opening 38 of the flushing area 37 to the ink recovery unit 32, and adds this ejection amount N to the previous recovery amount K of the ink recovery unit 32 to update the recovery amount K of the ink recovery unit 32. Furthermore, if the recovery amount K is less than the threshold value S, the control unit 66 maintains the rotation speed of the suction fan 44 of the ink recovery unit 32 at a constant rotation speed, and if the recovery amount K is equal to or greater than the threshold value S, the control unit 66 sets the rotation speed of the suction fan 44 of the ink recovery unit 32 to a rotation speed higher than the constant rotation speed.

[0068] As a result, the flow rate and flow velocity of the air inside the main body housing 41 of the ink recovery unit 32 do not decrease, and the ink recovery efficiency of the ink recovery unit 32 can be maintained.

[0069] As described above, in this embodiment, the amount K of ink recovered by the ink recovery unit 32 is determined for each ink recovery unit 32, and when the amount K of ink recovered by the ink recovery unit 32 becomes equal to or greater than the threshold value S, the rotation speed of the suction fan 44 of the ink recovery unit 32 is increased, thereby avoiding a decrease in the flow rate and speed of air inside the main body housing 41 of the ink recovery unit 32 and preventing a decrease in the efficiency of ink recovery by the ink recovery unit 32. Furthermore, there is no need to clean or replace any of the device's parts, such as the ink recovery unit 32.

[0070] In the above embodiment, the control unit 66 increases the rotation speed of the suction fan 44 when the recovery amount K updated in S106 is equal to or greater than the threshold value S, but the control unit 66 may also cause the display unit 62 to display a message urging the user to replace the ink recovery unit 32 when the recovery amount K updated in S106 reaches the limit (≫ threshold value S) for the amount of ink recovered by the ink recovery unit 32. Upon seeing this message, the user removes the ink recovery unit 32 that has reached its limit and installs a new ink recovery unit 32.

[0071] Furthermore, in the above embodiment, ink droplets for flushing are ejected while a color image is being formed on the recording paper P. However, the control unit 66 may also cause ink droplets for flushing to be ejected before or after the start or end of color image formation, i.e., when a color image is not being formed on the recording paper P. In this case, it is not necessary to determine the positional relationship between the position of the recording paper P on the conveyor belt 6 and each flushing area 37, or to select a flushing area 37 on the conveyor belt 6 that does not overlap with the recording paper P. For this reason, the control unit 66 may determine the timing at which each flushing area 37 moves and reaches between each line head 15B, 15C, 15M, and 15Y and each ink recovery unit 32, and cause the line head whose flushing area 37 has reached the flushing area 37 to eject ink droplets at the respective timing.

[0072] Furthermore, the configurations and processes of the above-described embodiments explained using FIGS. 1 to 7 are merely examples of the present invention, and the present invention is not limited to these configurations and processes. [Explanation of symbols]

[0073] 10. Inkjet recording device 11 Image reading unit 12 Image forming unit 14 Paper feed section 15B~15Y Line Head 31 Suction part 32 Ink recovery section 35 Belt sensor 36 Paper sensor 44 Suction fan 61 Operation section 62 Display section 63 Touch Panel 64 Memory section 65 Control Unit 66 Control Unit 67 Motor

Claims

1. a line head that ejects ink droplets; a conveyor belt that conveys recording paper onto which ink droplets ejected from the line head are applied, and has openings through which the ejected ink droplets pass; an ink recovery unit disposed opposite the line head with the conveyor belt interposed therebetween, for receiving and recovering the ink droplets that have passed through the openings; an airflow generating unit that generates an airflow for moving the ink droplets inside the ink recovery unit; a control unit that determines the amount of ink droplets recovered by the ink recovery unit, and when the amount of ink droplets recovered by the ink recovery unit becomes equal to or greater than a predetermined threshold, controls the air flow generating unit to promote the generation of an air flow by the air flow generating unit.

2. the airflow generating unit includes a fan that generates an airflow inside the ink recovery unit, 2. The inkjet recording apparatus according to claim 1, wherein the control unit controls the fan to increase the rotation speed of the fan when the amount of ink recovered by the ink recovery unit becomes equal to or greater than the threshold value.

3. the ink recovery unit includes a porous member therein that absorbs the ink droplets; 3. The ink jet recording apparatus according to claim 2, wherein the porous member defines a path for airflow generated inside the ink recovery section.

4. a drive unit that moves the conveyor belt, The control unit controlling the drive unit to move the conveyor belt and move the opening between the line head and the ink recovery unit, and controlling the line head to eject the ink droplets from the line head toward the opening, 2. The inkjet recording apparatus according to claim 1, wherein the ejection amount of the ink droplets is counted, and the counted ejection amount is calculated as the amount of ink recovered by the ink recovery section.

Images