INKJET RECORDING DEVICE

An inkjet recording device includes a conveying unit that conveys a paper sheet by use of an endless conveyor belt, a recording unit that includes a recording head disposed to face a carrying surface of the conveyor belt so as to eject ink through ink ejection nozzles of the recording head to the paper shed being conveyed by the conveyor belt, a sucking roller that, on an upstream side of the recording unit in a sheet conveying direction, makes contact with the paper sheet being conveyed and rotates in that state, and a sucking device. The sucking roller is columnar in outer shape and has many air sucking holes formed in a side surface thereof so that air in a vicinity of the sucking roller is sucked through the air sucking holes by the sucking device.

INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2021-180107 filed on Nov. 4, 2021, the entire contents of which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to an inkjet recording device that ejects ink through ink ejection nozzles of a recording head so as to perform recording.

As a recording device such as a facsimile machine, a copier, or a printer, an inkjet recording device is widely used, which ejects ink through the nozzles of the recording head to form an image, so that a high definition image can be formed.

Such an inkjet recording device has a problem that paper dust generated from a paper sheet as a recording medium might clog the nozzle and cause a nozzle ejection failure (missing dot), resulting in lowering of image quality.

SUMMARY

An inkjet recording device according to an aspect of the present disclosure includes a conveying unit, a recording unit, a sucking roller, and a sucking device. The conveying unit conveys a paper sheet by use of an endless conveyor belt. The recording unit includes a recording head disposed to face a carrying surface of the conveyor belt so as to eject ink through ink ejection nozzles of the recording head to the paper sheet being conveyed by the conveyor belt. On an upstream side of the recording unit in a sheet conveying direction, the sucking roller makes contact with the paper sheet being conveyed and rotates in that state. The sucking device is joined to the sucking roller. The sucking roller is columnar in outer shape and has many air sucking holes formed in a side surface thereof so that air in a vicinity of the sucking roller is sucked through the air sucking holes by the sucking device.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure is described with reference to the drawings.FIG.1is a view illustrating a schematic configuration of a printer100of an inkjet recording method according to an embodiment of the present disclosure.FIG.2is a sectional view illustrating a structure of a first belt conveying unit5, a recording unit9, a second belt conveying unit12, and their vicinity of the printer100illustrated inFIG.1.FIG.3is a plan view from above of the first belt conveying unit5and the recording unit9of the printer100illustrated inFIG.1.

As illustrated inFIG.1, the printer100includes a sheet feed cassette2aas a sheet housing unit disposed on the lower side in a printer main body1, and a manual sheet feeding tray2bis provided outside a right side surface of the printer main body1. A sheet feeding device3ais disposed downstream of the sheet feed cassette2ain a sheet conveying direction, i.e. on the upper right side of the sheet feed cassette2ainFIG.1. In addition, a sheet feeding device3bis disposed downstream of the manual sheet feeding tray2bin the sheet conveying direction. i.e. on the left side of the manual sheet feeding tray2binFIG.1. The sheet feeding devices3aand3benable to separate and feed paper sheets (sheets) P one by one.

In addition, a first sheet conveying path4ais provided inside the printer100. The first sheet conveying path4ais positioned on the upper right side of the sheet feed cassette2a, i.e. on the left side of the manual sheet feeding tray2b. The paper sheet P sent out from the sheet feed cassette2apasses through the first sheet conveying path4aand is conveyed vertically upward along the side surface of the printer main body1. The paper sheet sent out from the manual sheet feeding tray2bpasses through the first sheet conveying path4aand is conveyed substantially horizontally to the left.

A registration roller pair13is provided at a downstream end of the first sheet conveying path4ain the sheet conveying direction. Further, the first belt conveying unit (conveying unit)5and the recording unit9are disposed near the registration roller pair13on the downstream side. The registration roller pair13corrects a skew of the paper sheet P, and sends out the paper sheet P to the first belt conveying unit5in synchronization with an ink ejection operation by the recording unit9.

In addition, between the registration roller pair13and the first belt conveying unit5, there is disposed a contact image sensor (CIS)20as a sheet detection sensor for detecting an end position of the paper sheet P in its width direction (in a direction perpendicular to the sheet conveying direction).

The first belt conveying unit5includes an endless first conveyor belt8(seeFIG.2) stretched around a first drive roller6and a first driven roller7. The paper sheet P sent out from the registration roller pair13passes below the recording unit9, in the state where it is sucked and held on a carrying surface8aof the first conveyor belt8.

A sucking roller60is disposed upstream of the recording unit9in the sheet conveying direction and at a position facing an upstream end of the first conveyor belt8. The sucking roller60makes contact with the carrying surface8aof the first conveyor belt8or the paper sheet P placed on the carrying surface8aso as to be conveyed, and rotates in that state following rotation of the first conveyor belt8. A detailed configuration of the sucking roller60will be described later.

A plate-shaped member25is disposed between the recording unit9and the sucking roller60. The plate-shaped member25is secured to a head housing10holding line heads11C,11M,11Y, and11K and is disposed substantially parallel to the carrying surface8aof the first conveyor belt8at a predetermined gap therefrom. The plate-shaped member25faces the first conveyor belt8over an entire area in a width direction thereof (a direction perpendicular to a plane on whichFIG.2is drawn), and a space is formed between a lower surface of the plate-shaped member25and the carrying surface8a.

A first sheet sucking unit30is provided at a location facing a backside of the carrying surface8aof the first conveyor belt8, inside the loop of the first conveyor belt8. The first sheet sucking unit30has many holes30aformed in an upper surface thereof for sucking air, and inside the first sheet sucking unit30, there is provided a first fan30bthat can suck air downward through the upper surface. In addition, the first conveyor belt8also has many air holes8bfor sucking air (seeFIG.3). With the configuration described above, the first belt conveying unit5conveys the paper sheet P while sucking and holding the same on the carrying surface8aof the first conveyor belt8.

The recording unit9includes the line heads11C,11M,11Y, and11K that perform recording of an image on the paper sheet P being conveyed while sucked and held on the carrying surface8aof the first conveyor belt8. Inks in the line heads11C to11K are sequentially ejected therefrom to the paper sheet P sucked on the first conveyor belt8so as to correspond to information of image data received from an external computer or the like. With this configuration, four color inks of cyan, magenta, yellow, and black are superimposed so that a full-color image is recorded on the paper sheet P. The printer100can also record a monochrome image.

As illustrated inFIG.3, the recording unit9includes the head housing10and the line heads11C,11M,11Y, and11K held by the head housing10. Each of the line heads11C to11K has a recording area of a width not smaller than that of the paper sheet P conveyed thereto. Each of the line heads11C to11K is supported at a height to form a predetermined gap (for example, 1 mm) between itself and the carrying surface8aof the first conveyor belt8and includes three recording heads17ato17carranged in a zigzag manner along a sheet width direction (a B-B′ direction) orthogonal to the sheet conveying direction. Many ink ejection nozzles18are arranged in an ink ejection surface of each of the recording heads17ato17c.

The recording heads17ato17cconstituting each of the line heads11C to11K are supplied with ink of the corresponding color among the four color inks (cyan, magenta, yellow, and black color inks), which are respectively stored in ink tanks (not shown).

Each of the recording heads17ato17ccan eject ink through the ink ejection nozzles18corresponding to print positions in accordance with image data received from an external computer or the like, to the paper sheet P being conveyed while sucked and held on the carrying surface8aof the first conveyor belt8. With this configuration, the cyan, magenta, yellow, and black color inks are superimposed so that a color image is formed on the paper sheet P on the first conveyor belt8.

On the downstream side (the left side inFIG.1) of the first belt conveying unit5in the sheet conveying direction, there is disposed the second belt conveying unit12. The paper sheet P with the image recorded in the recording unit9is sent to the second belt conveying unit12, and passes through the second belt conveying unit12while the inks on a surface of the paper sheet P are dried.

The second belt conveying unit12includes an endless second conveyor belt40stretched around a second drive roller41and a second driven roller42. The second conveyor belt40is driven by the second drive roller41to turn in a counterclockwise direction inFIG.2. The paper sheet P with the image recorded in the recording unit9is conveyed by the first belt conveying unit5in an arrow X direction, transferred to the second conveyor belt40, and is conveyed in an arrow Z direction inFIG.2.

A second sheet sucking unit43is provided at a location facing a backside of a carrying surface40aof the second conveyor belt40, inside the loop of the second conveyor belt40. The second sheet sucking unit43has many holes43aformed in an upper surface thereof for sucking air, and inside the second sheet sucking unit43, there is provided a second fan43bthat can suck air downward through the upper surface. In addition, the second conveyor belt40also has many air holes for sucking air (not shown). With the configuration described above, the second belt conveying unit12conveys the paper sheet P while sucking and holding the same on the carrying surface40aof the second conveyor belt40.

In addition, a conveyance guide part50is provided at a position facing the carrying surface40aof the second conveyor belt40. The conveyance guide part50constitutes a sheet conveyance path together with the carrying surface40aof the second conveyor belt40and suppresses warping or fluttering of the paper sheet P sucked and held on the carrying surface40aby the second sheet sucking unit43.

A decurler unit14is provided downstream of the second belt conveying unit12in the sheet conveying direction and in a vicinity of a left side surface of the printer main body1. The paper sheet P after the inks are dried in the second belt conveying unit12is conveyed to the decurler unit14, which corrects a curl of the paper sheet P.

On the downstream side (the upper side inFIG.1) of the decurler unit14in the sheet conveying direction, there is provided a second sheet conveying path4b. When double-sided recording is not performed, the paper sheet P after passing through the decurler unit14is discharged onto a sheet discharge tray15provided outside a left side surface of the printer100, from the second sheet conveying path4bvia a discharge roller pair. When the double-sided recording is performed on the paper sheet P, the paper sheet P, after recording on one side and passing through the second belt conveying unit12and the decurler unit14, passes through the second sheet conveying path4band is conveyed to a reverse conveying path16. The paper sheet P sent to the reverse conveying path16is changed in the conveying direction so as to be upside down, passes through an upper part of the printer100, and is conveyed to the registration roller pair13. After that, the paper sheet P is conveyed to the first belt conveying unit5again, in the state where the side with no image recorded faces upward.

In addition, a maintenance unit19is disposed below the second belt conveying unit12. When performing maintenance of the recording heads17, the maintenance unit19moves to below the recording unit9, wipes ink pushed out (purged) from the ink ejection nozzles18(seeFIG.3) of the recording heads17, and collects the wiped ink.

FIG.4is a block diagram illustrating an example of a control path of the printer100according to this embodiment. The printer100further includes, in addition to the configuration described above, belt drive motors21and22, fan drive motors23and24, an operation panel27, a storage unit28, a communication unit29, and a sucking device70.

The belt drive motors21and22respectively drive the first drive roller6and the second drive roller41to rotate, so that the first conveyor belt8and the second conveyor belt40can turn. The fan drive motors23and24respectively drive the first fan30bof the first sheet sucking unit30and the second fan43bof the second sheet sucking unit43to rotate.

The operation panel27is an operation unit for receiving various setting inputs. For instance, by operating the operation panel27, a user can input a size of the paper sheets P set in the sheet feed cassette2aor on the manual sheet feeding tray2b, i.e. information of a size of the paper sheet P that is conveyed by the first conveyor belt8. In addition, by operating the operation panel27, the user can also input the number of the paper sheets P to be printed or instruct a start of a print job. In addition, the operation panel27also has a function as a notification device for notifying about an operating state of the printer100.

The storage unit28is a memory for storing an operation program of a control unit110and various sets of information, and it includes a read only memory (ROM), a random access memory (RAM), a nonvolatile memory, and the like. The information set by the operation panel27is stored in the storage unit28.

The communication unit29is a communication interface for communicating information with an external device (such as a personal computer (PC)). For instance, when the user operates the PC and sends a print command with image data to the printer100, the image data and the print command are input to the printer100via the communication unit29. In the printer100, a main control portion110acontrols the recording heads17ato17cto eject ink on the basis of the image data, so that an image can be recorded on the paper sheet P.

The sucking device70is joined to the sucking roller60and sucks paper dust of the paper sheet P to be conveyed to the recording unit9via the sucking roller60.

In addition, the printer100according to this embodiment includes the control unit110. The control unit110is constituted of a central processing unit (CPU) and a memory, for example. Specifically, the control unit110includes the main control portion110a, a sheet suction control portion110b, a sheet supply control portion110c, and a maintenance control portion110d.

The main control portion110acontrols operations of individual units in the printer100. For instance, drive of each roller in the printer100, ink ejection from the recording heads17ato17cwhen recording an image, and the like are controlled by the main control portion110a. The main control portion110aalso drives the sucking device70to remove paper dust of the paper sheet P to be conveyed to the recording unit9.

The sheet suction control portion110bsends a control signal to the fan drive motors23and24so as to control rotations of the first fan30band the second fan43b, and thus a state of the paper sheet P sucked and held on the first conveyor belt8or the second conveyor belt40can be controlled.

The sheet supply control portion110cis a recording medium supply control portion that controls the registration roller pair13as a recording medium supply unit. For instance, the sheet supply control portion110ccontrols the registration roller pair13based on a detection timing of a rear end of the paper sheet P by the CIS20, and thus controls a conveyance timing of the following paper sheet P.

The maintenance control portion110dcontrols the recording heads17ato17cto perform the purge operation described above in which the ink ejection nozzles18push out ink in a forced manner. When the maintenance control portion110dcontrols the recording heads17ato17cto perform the purge operation, it also controls drive of the maintenance unit19described above (e.g. movement to below the recording unit9and retraction).

Note that the control unit110may further include a calculation portion that performs necessary calculation and a time measuring portion that measures time. In addition, the main control portion110amay also works as the calculation portion or the time measuring portion described above.

As described above, there is the problem that paper dust generated from the paper sheet P might clog the ink ejection nozzles18of the recording heads17and cause an ink ejection failure (missing dot) of the ink ejection nozzles18, resulting in lowering of image quality. Therefore, the printer100according to this embodiment uses the sucking roller60and the sucking device70to suck paper dust of the paper sheet P to be conveyed to the recording unit9.

FIG.5is a perspective view illustrating an example of the sucking roller60used in the printer100according to this embodiment.FIG.6is a cross-sectional view of a roller main body61of the sucking roller60shown inFIG.5as cut in a direction (a radial direction) orthogonal to an axial direction thereof.FIG.7is a sectional side view illustrating a flow path of an airflow, which includes the sucking roller60and the sucking device70, and is also a sectional view of the sucking roller60as cut along an axial direction thereof. A left side inFIG.7corresponds to a front side of the printer100, and a right side therein corresponds to a rear side of the printer100.

The sucking roller60has a columnar shape and includes the roller main body61of a cylindrical shape and a first rotary shaft62aand a second rotary shaft62bthat are provided respectively at both ends of the roller main body61in the axial direction. The roller main body61is hollow and has many air sucking holes63formed in an outer circumferential surface (a columnar side surface) thereof. The air sucking holes63have a diameter of approximately 1 to 2 mm.

The first rotary shaft62ahas a hollow cylindrical shape with both ends thereof open and is secured on the rear side in the printer100. That is, the first rotary shaft62ais provided at one end of the roller main body61in the axial direction. One end of the first rotary shaft62ais inserted into the one end of the roller main body61in the axial direction. A first bearing65ais secured to the one end of the roller main body61in the axial direction so that the one end of the roller main body61in the axial direction is supported so as to be rotatable about the first rotary shaft62aas a support axis. That is, one end of the sucking roller60(on the rear side) is supported so as to be rotatable by frictional motion between the first rotary shaft62aand the first bearing65a. The sucking device70is joined to the roller main body61via the first rotary shaft62a. Specifically, the other end of the first rotary shaft62ais connected to the sucking device70.

The second rotary shaft62bis secured to an end (the other end) of the roller main body61in the axial direction on the opposite side to the first rotary shaft62aand is rotatably supported by a second bearing65bthat is secured on the front side in the printer100. That is, the other end of the sucking roller60(on the front side) is supported so as to be rotatable by frictional motion between the second rotary shaft62band the second bearing65b.

The sucking device70includes a sucking fan71and a filter73. As shown by arrows inFIG.7, the sucking fan71sucks air in a vicinity of the sucking roller60into the sucking device70via the air sucking holes63and the first rotary shaft62a. The filter73is disposed upstream of the sucking fan71with respect to a flow path of an airflow and collects paper dust sucked together with the air into the sucking device70. The air sucked by the sucking fan71is discharged to the outside of the printer100via an exhaust duct (not shown). The filter73may be disposed downstream of the sucking fan71with respect to a flow path of an airflow.

At a time of image recording on the paper sheet P, the main control portion110atransmits a control signal to the sucking device70so as to drive the sucking fan71to rotate. With this configuration, before the paper sheet P fed from the sheet feed cassette2aor the manual sheet feeding tray2bis conveyed to the recording unit9, paper dust adhering to the paper sheet P is sucked together with air through the air sucking holes63into the sucking roller60rotating in contact with the paper sheet P. The paper dust sucked into the sucking roller60passes through the first rotary shaft62aand then is collected by the sucking filter73in the sucking device70. Accordingly, it is possible to reduce paper dust adhering to the paper sheet P to be conveyed to the recording unit9and thus to suppress clogging of the ink ejection nozzles18caused by paper dust.

In addition, between the sucking roller60and the recording unit9, the plate-shaped member25(seeFIG.2) is disposed to face the carrying surface8aof the first conveyor belt8, and air that has passed through a space between the plate-shaped member25and the carrying surface8ais sucked into the sucking roller60. That is, air flows to the sucking roller60along a surface of the paper sheet P sucked and held on the carrying surface8a, and thus paper dust adhering to the paper sheet P can be efficiently sucked and removed. Here, a gap between the plate-shaped member25and the carrying surface8ais set to a value not more than a preset threshold value, and thus it is possible to increase a velocity of an airflow between the plate-shaped member25and the carrying surface8aand thus to enhance paper dust sucking efficiency.

FIG.8is a perspective view illustrating a modification example of the sucking roller60used in the printer100.FIG.9is a cross-sectional view of a roller main body61of the sucking roller60shown inFIG.8as cut in a direction (a radial direction) orthogonal to an axial direction thereof. In the modification example shown inFIG.8andFIG.9, many concaves66are formed in a surface of the roller main body61of the sucking roller60. The concaves66have a circular shape and are formed at substantially regular intervals in a circumferential direction and an axial direction of the roller main body61. The concaves66have a diameter of approximately 4 to 5 mm and a depth of approximately 1 mm. Further, air sucking holes63are formed in bottom surfaces of the concaves66, respectively. As for other parts of the sucking roller60and the sucking device70, configurations thereof are similar to those shown inFIG.5toFIG.7.

When air is sucked through the air sucking holes63into the sucking roller60at a time of image recording on the paper sheet P, the paper sheet P passing through the sucking roller60might be wrapped around the sucking roller60under a negative pressure, causing a paper jam.

To avoid the above situation, as shown inFIG.8andFIG.9, the concaves66are provided in an outer circumferential surface of the roller main body61, and the air sucking holes63are formed in the bottom surfaces of the concaves66, respectively, so that a gap is formed between the paper sheet P being in contact with an outer circumferential surface of the sucking roller60and each of the air sucking holes63. As a result, a sucking force of the sucking roller60with respect to the paper sheet P is reduced, and thus it is possible to suppress a phenomenon in which the paper sheet P is wrapped around the sucking roller60.

FIG.10is a perspective view illustrating another modification example of the sucking roller60used in the printer100.FIG.11is a cross-sectional view of a roller main body61of the sucking roller60shown inFIG.10as cut in a direction (a radial direction) orthogonal to an axial direction thereof. In the modification example shown inFIG.10andFIG.11, a plurality of grooves67is formed in a surface of the roller main body61of the sucking roller60so as to extend along the axial direction. The grooves67are formed at substantially regular intervals in a circumferential direction of the roller main body61and extend up to both ends of the roller main body61in the axial direction. The grooves67have a groove width of approximately 4 to 5 mm and a depth of approximately 1 mm. Further, a plurality of air sucking holes63is formed at constant intervals in a bottom surface of each of the grooves67. As for other parts of the sucking roller60and the sucking device70, configurations thereof are similar to those shown inFIG.5toFIG.7.

According to a configuration shown inFIG.10andFIG.11, by the grooves67, a gap is formed between the paper sheet P being in contact with an outer circumferential surface of the sucking roller60and the air sucking holes63. In addition, even in a state where the paper sheet P is in contact with the outer circumferential surface of the sucking roller60, air flows into the air sucking holes63from both ends of the grooves67, and thus there occurs a loss in negative pressure exerted in such a direction as to suck the paper sheet P. As a result, a sucking force of the sucking roller60with respect to the paper sheet P is reduced, and thus it is possible to suppress the phenomenon in which the paper sheet P is wrapped around the sucking roller60.

FIG.12is a perspective view illustrating still another modification example of the sucking roller60used in the printer100.FIG.13is a cross-sectional view of a roller main body61of the sucking roller60shown inFIG.12as cut in a direction (a radial direction) orthogonal to an axial direction thereof. In the modification example shown inFIG.12andFIG.13, the roller main body61is hollow and has many air sucking holes63formed in an outer circumferential surface thereof. Further, an elastic layer68having an open-cell structure is stacked on the outer circumferential surface of the roller main body61. The elastic layer68has a thickness of 3 to 5 mm and is made of, for example, polyethylene or polyurethane sponge. As for other parts of the sucking roller60and the sucking device70, configurations thereof are similar to those shown inFIG.5toFIG.7.

According to a configuration shown inFIG.12andFIG.13, by the elastic layer68, a gap is formed between the paper sheet P being in contact with an outer circumferential surface of the sucking roller60and the air sucking holes63. In addition, since the elastic layer68has the open-cell structure, even in the state where the paper sheet P is in contact with the outer circumferential surface of the sucking roller60, air passes through the elastic layer68and flows into the air sucking holes63. With this configuration, there occurs a loss in negative pressure exerted in such a direction as to suck the paper sheet P. As a result, a sucking force of the sucking roller60with respect to the paper sheet P is reduced, and thus it is possible to suppress the phenomenon in which the paper sheet P is wrapped around the sucking roller60.

In a case where the sucking roller60shown inFIG.12andFIG.13is used for a long period of time, paper dust might be deposited on a surface of the elastic layer68, causing deterioration in sucking performance. To avoid this, there may be provided a cleaning mechanism that removes paper dust on the surface of the elastic layer68. As the cleaning mechanism, for example, a cleaning brush, a cleaning roller, a scraper, or the like can be used.

Other than the above, without being limited to the embodiment described above, the present disclosure can be variously modified within a scope not departing from the spirit thereof. For example, while the above embodiment describes a case where the paper sheet P is conveyed in a state of being sucked by negative-pressure suction on the first conveyor belt8and the second conveyor belt40, the first conveyor belt8and the second conveyor belt40may be charged so that the paper sheet P is conveyed in a state of being sucked by electrostatic suction on the first conveyor belt8and the second conveyor belt40(an electrostatic suction method).

In addition, the above embodiment describes the line head type printer100as the inkjet recording device, which performs recording with the line heads11C to11K, each of which includes the recording heads17ato17ehaving the many ink ejection nozzles18arranged in the sheet width direction, but the present disclosure can be similarly applied to a serial type inkjet recording device that performs recording with a recording head17that moves over a sheet.

The present disclosure can be used for inkjet recording devices that perform recording by ejecting ink through the ink ejection nozzles of the recording head. Using the present disclosure, it is possible to provide the inkjet recording device that can effectively remove paper dust generated from a paper sheet, with a simple configuration.