INKJET RECORDING APPARATUS

An inkjet recording apparatus includes a conveyance belt, a sheet suction portion, a sheet conveyance portion, a recording portion, a suction roller, and an exhaust fan. The suction roller, at an upstream side of the recording portion with respect to a sheet conveyance direction, brings the sheet into contact with the outer circumferential surface of the conveyance belt. The exhaust fan, at an upstream side of the suction roller with respect to the sheet conveyance direction, sucks air existing over the conveyance belt. The exhaust fan causes air existing over the conveyance belt to flow through intervals between adjacent ones of roller portions of the suction roller in the sheet width direction, and thereby sucks and discharges air in a direction away from the conveyance belt.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority from Japanese Patent Application No. 2022-058430 filed on Mar. 31, 2022, the contents of which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to an inkjet recording apparatus.

Inkjet recording apparatuses that record an image by ejecting ink from nozzles provided in recording heads are capable of recording a high-definition image and thus have been widely used as recording apparatuses such as facsimile machines, copiers, and printers. Such inkjet recording apparatuses suffer a problem that paper dust generated from paper sheets used as a recording medium may become stuck in a nozzle to cause poor ejection from the nozzle, resulting in poor image quality.

SUMMARY

According to one aspect of the present disclosure, an inkjet recording apparatus includes a sheet conveyance portion, a recording portion, a suction roller, and an exhaust fan. The sheet conveyance portion includes a conveyance belt and a sheet suction portion, and conveys a sheet. The conveyance belt is endless, and a plurality of ventilation holes are formed therein. The sheet suction portion is disposed inside the conveyance belt, includes a suction fan that sucks air through the ventilation holes, and holds a sheet by suction on an outer circumferential surface of the conveyance belt. The recording portion is disposed opposite the outer circumferential surface of the conveyance belt, includes a recording head from which ink is ejected, and records an image by ejecting ink onto the sheet held by suction on the conveyance belt. The suction roller is disposed opposite such part of the outer circumferential surface of the conveyance belt as is located upstream of the recording portion with respect to a sheet conveyance direction, at an upstream-side end part of the sheet suction portion, and brings the sheet into contact with the outer circumferential surface of the conveyance belt. The exhaust fan is disposed adjacent to an upstream side of the suction roller with respect to the sheet conveyance direction, and sucks air existing over the conveyance belt. The suction roller includes a rotation shaft and a plurality of roller portions. The rotation shaft extends in a sheet width direction perpendicular to the sheet conveyance direction. The plurality of roller portions are arrayed on the rotation shaft at intervals along the sheet width direction so as to contact the sheet, and rotate about the rotation shaft. The exhaust fan causes air existing over the conveyance belt to pass through the intervals between adjacent ones of the roller portions in the sheet width direction, and thereby sucks and discharges the air in a direction away from the conveyance belt.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. The present disclosure, however, is not limited to what is specifically described below.

FIG.1is a schematic sectional front view of an inkjet recording apparatus1according to an embodiment.FIG.2is a top view of a recording portion5and the vicinity thereof in the inkjet recording apparatus1shown inFIG.1. The inkjet recording apparatus1is an inkjet recording printer, for example. As shown inFIGS.1and2, the inkjet recording apparatus1includes an apparatus main body2, a sheet feed portion3, a sheet conveyance portion4, the recording portion5, a drying portion6, and a control portion7.

The sheet feed portion3is disposed in a lower part of the apparatus main body2, for example. The sheet feed portion3stores a plurality of sheets (of a recording medium) S, and, during image recording, feeds out the sheets S separately one by one. The sheet conveyance portion4conveys a sheet S fed out from the sheet feed portion3to the recording portion5and then to the drying portion6, and further discharges the sheet S, having been subjected to recording and drying, into a sheet discharge portion21. In a case where double-sided printing is to be performed, the sheet conveyance portion4sorts the sheet S having been subjected to recording and drying on its first side toward a reversing conveyance portion43, where the conveyance direction of the sheet S is switched and the sheet S is reversed upside down, and then the sheet S is once again conveyed to the recording portion5and the drying portion6.

The sheet conveyance portion4includes a first belt conveyance portion41and a second belt conveyance portion42. The first belt conveyance portion41and the second belt conveyance portion42convey a sheet S by holding it by suction on outer circumferential surfaces (upper surfaces) of a first conveyance belt411and a second conveyance belt421, respectively, which are both endless belts. The first belt conveyance portion41is disposed below the recording portion5to convey a sheet S. The second belt conveyance portion42is located downstream of the first belt conveyance portion41in a sheet conveyance direction Dc, and is disposed in the drying portion6to convey a sheet S.

The recording portion5is disposed opposite the outer circumferential surface (the upper surface) of the first conveyance belt411. That is, the recording portion5is disposed so as to be opposite a sheet S that is conveyed in a state held by suction on the outer circumferential surface (the upper surface) of the first conveyance belt411. The recording portion5is disposed above the first conveyance belt411at a predetermined interval therefrom.

The recording portion5holds head units51B,51C,51M, and51Y corresponding to four colors of black, cyan, magenta, and yellow, respectively. The head units51B,51C,51M, and51Y are disposed side by side along the sheet conveyance direction Dc such that their longitudinal direction is parallel to a sheet width direction Dw perpendicular to the sheet conveyance direction Dc. The four head units51B,51C,51M, and51Y have basically the same structure, and thus, in the following descriptions, the suffixes “B”, “C”, “M”, and “Y” indicating colors may be omitted unless specific distinction is necessary.

The head units51for the different colors each include a line recording head52for inkjet recording. Each of the head units51for the different colors includes a plurality of (for example, three (52a,52b,52c)) recording heads arrayed in a staggered formation along the sheet width direction Dw.

Each of the recording heads52has a plurality of ink ejection nozzles521in a bottom part thereof. The plurality of ink ejection nozzles521are disposed one adjacent another along the sheet width direction Dw, and ink can be ejected therefrom over an entire recording region on a sheet S. That is, each of the recording heads52includes the plurality of ink ejection nozzles521that eject ink onto a sheet S. The recording portion5causes the head units51B,51C,51M, and51Y for the four colors to sequentially eject ink from their respective recording heads52onto a sheet S conveyed in a state held by suction on the first conveyance belt411, and thereby records a full-color or monochrome image on the sheet S.

The drying portion6is disposed downstream of the recording portion5in the sheet conveyance direction Dc, and is provided with the second belt conveyance portion42. A sheet S on which an ink image has been recorded in the recording portion5is conveyed through the drying portion6in a state held by suction on the second conveyance belt421, during which period the ink is dried.

The control portion7includes a CPU, a storage portion, and other electronic circuits and parts (of which none is illustrated). The CPU controls operations of various components provided in the inkjet recording apparatus1based on a control program and control data stored in the storage portion, and thereby performs processes related to functions of the inkjet recording apparatus1. The sheet feed portion3, the sheet conveyance portion4, the recording portion5, and the drying portion6each individually receive instructions from the control portion7, and cooperate with each other to perform recording on a sheet S.

FIG.3is a partial sectional front view of the recording portion5and the vicinity thereof in the inkjet recording apparatus1shown inFIG.1.FIG.4is a partial sectional front view showing an upstream side, in a sheet conveyance direction, of the recording portion5and the vicinity thereof shown inFIG.3.FIG.5is a top view of a suction roller47shown inFIG.4. InFIGS.3,4, and5, white arrows outlined with broken lines indicate air flows generated when a later-described exhaust fan8is driven and directions of the air flows.

As shown inFIGS.3and4, the sheet conveyance portion4further includes a pair of registration rollers45, a sheet suction portion46, and a suction roller47.

The pair of registration rollers45are disposed downstream of the sheet feed portion3in the sheet conveyance direction Dc. Immediately close to a downstream side of the pair of registration rollers45in the sheet conveyance direction Dc, the first belt conveyance portion41and the recording portion5are disposed. Each roller in the pair of registration rollers45is supported to be rotatable about a rotation shaft extending along the sheet width direction Dw (seeFIG.2).

A sheet S fed out from the sheet feed portion3passes through the sheet conveyance portion4to reach where the pair of registration rollers45are located. The control portion7controls the pair of registration rollers45to correct skewed feeding of the sheet S and also to feed out the sheet S toward the first belt conveyance portion41with timing coordinated with timing of an ink ejection operation executed by the recording portion5.

The sheet conveyance portion4includes a registration sensor (unillustrated). The registration sensor is disposed immediately close to an upstream side of the pair of registration rollers45in the sheet conveyance direction Dc. The registration sensor detects a sheet S when the sheet reaches the pair of registration rollers45after being fed out from the sheet feed portion3. The control portion7receives, from the registration sensor, a detection signal indicating detection of the sheet S, and based on the detection signal, the control portion7controls rotation of the pair of registration rollers45.

The first belt conveyance portion41is disposed below the recording portion5. The first belt conveyance portion41holds a sheet S on its upper surface by suction, and conveys the sheet S along the sheet conveyance direction Dc. The first belt conveyance portion41includes the first conveyance belt411and a plurality of rollers412.

The first conveyance belt411is an endless belt, and is stretched by the plurality of rollers412, which are disposed inside the first conveyance belt411. The rollers412are disposed inside the first conveyance belt411, and are supported to be rotatable about rotation shafts extending along the sheet width direction Dw (seeFIG.2). Among the plurality of rollers412, one is a driving roller, which causes the first conveyance belt411to rotate such that an upper side thereof moves in the sheet conveyance direction Dc.

As shown inFIG.2, the first conveyance belt411has a plurality of ventilation holes4111. The ventilation holes4111penetrate through the first conveyance belt411from inside through outside. The outer circumferential surface of the first conveyance belt411is a sheet conveyance surface. A sheet S, in a state held on the sheet conveyance surface of the first conveyance belt411, is conveyed to a position opposite the recording heads52.

The sheet suction portion46is disposed inside the first conveyance belt411. More specifically, the sheet suction portion46is located in an upper part inside the first conveyance belt411, and is disposed opposite an upper-side part of the inner circumferential surface (a back side) of the first conveyance belt411, the upper-side part of the inner circumferential surface of the first conveyance belt411being an opposite surface of the sheet conveyance surface of the first conveyance belt411. The sheet suction portion46includes a housing461and an air suction fan462.

The housing461is formed as a substantially rectangular-parallelepiped box body, for example, and includes a suction chamber4611that is surrounded by walls. The suction chamber4611is disposed below the head units51B,51C,51M and51Y so as to be opposite the upper-side part of the inner circumferential surface (the back side) of the first conveyance belt411, which is the opposite surface of the sheet conveyance surface of the first conveyance belt411, over a region from a position upstream of the head unit51B for black in the sheet conveyance direction Dc to the head unit51Y for yellow.

The housing461has a plurality of air suction holes4612that are formed in an upper surface thereof, the upper surface being disposed over the suction chamber4611. The plurality of air suction holes4612penetrate through the upper surface of the housing461in an up-down direction.

The air suction fan462is disposed at a position that is inside the housing461and is under the suction chamber4611. When the air suction fan462is driven, the sheet suction portion46sucks air through the air suction holes4612and the ventilation holes4111(seeFIG.2), and thereby holds a sheet S by suction on the sheet conveyance surface of the first conveyance belt411.

The suction roller47is disposed opposite such part of the sheet conveyance surface of the first conveyance belt411as is located upstream of the recording portion5in the sheet conveyance direction Dc, at an upstream-side end part of the sheet suction portion46. In other words, the suction roller47is disposed above the upstream-side end part of the housing461in the sheet conveyance direction Dc, with the first conveyance belt411therebetween. The suction roller47is supported to be rotatable about a rotation shaft extending along the sheet width direction Dw (seeFIG.2).

An outer circumferential surface of the suction roller47contacts the sheet conveyance surface of the first conveyance belt411. By contacting the first conveyance belt411, for example, the suction roller47is caused to rotate following rotation of the first conveyance belt411. The suction roller47brings a sheet S conveyed thereto from the pair of registration rollers45into contact with the sheet conveyance surface of the first conveyance belt411.

As shown inFIG.5, the suction roller47includes a rotation shaft471and a plurality of roller portions472. The rotation shaft471extends in the sheet width direction Dw, and is supported to be rotatable about an axis line thereof. To the rotation shaft471, the plurality of roller portions472are fixed. The plurality of roller portions472are arrayed on the rotation shaft471at intervals along the sheet width direction Dw. The plurality of roller portions472come into contact with the sheet S conveyed on the first conveyance belt411, and rotate about the rotation shaft471.

Further, the inkjet recording apparatus1includes the exhaust fan8shown inFIGS.3and4. The exhaust fan8is disposed adjacent to an upstream side of the suction roller47in the sheet conveyance direction Dc. In other words, the exhaust fan8is disposed upstream of the sheet suction portion46in the sheet conveyance direction Dc. The exhaust fan8is disposed such that an air suction surface is opposite the sheet conveyance surface of the first conveyance belt411, that is, opposite the sheet S conveyed on the first conveyance belt411.

When driven, the exhaust fan8sucks air existing over the first conveyance belt411. At this time, air existing over such part of the first conveyance belt411as is located downstream of the suction roller47in the sheet conveyance direction Dc is sucked by the exhaust fan8through the intervals between adjacent ones of the roller portions472in the sheet width direction Dw. That is, the exhaust fan8causes the air existing over the first conveyance belt411to pass through the intervals between adjacent ones of the roller portions472in the sheet width direction Dw, and thereby sucks and discharges the air in a direction away from the first conveyance belt411.

According to the above structure, by the exhaust fan8, which is disposed upstream of the sheet suction portion46in the sheet conveyance direction Dc, paper dust on the first conveyance belt411is sucked and discharged together with air. Thereby, it is possible to effectively remove paper dust generated from a sheet S while maintaining suitable sheet conveying performance.

Here, on an exhaust side of the exhaust fan8, there is provided an exhaust duct (unillustrated) extending to an exterior wall of the apparatus main body2, for example. Further, on a suction side of the exhaust fan8or inside the exhaust duct, there may be provided a filter (unillustrated) for trapping paper dust and the like included in the air sucked by the exhaust fan8.

FIG.6is a top view of a suction roller48according to a modified example. InFIG.6, white arrows outlined with broken lines indicate air flows generated when the exhaust fan8is driven and directions of the air flows.

As shown inFIG.6, a sheet conveyance portion4of the modified example includes a plurality of suction rollers48. In the present modified example, the sheet conveyance portion4includes two suction rollers48. The two suction rollers48are disposed side by side in a row along the sheet conveyance direction Dc. These two suction rollers48are similar to the suction roller47shown isFIG.4in that they are disposed opposite such part of the sheet conveyance surface of the first conveyance belt411as is located upstream of the recording portion5in the sheet conveyance direction Dc, at an upstream-side end part of the sheet suction portion46.

According to the above structure, it is possible to improve accuracy of contact of a sheet S with respect to the sheet conveyance surface of the first conveyance belt411. Accordingly, it is possible to achieve improved sheet conveyance performance.

The two suction rollers48each include a rotation shaft481and a plurality of roller portions482. In each of the suction rollers48, intervals Rs between adjacent ones of the roller portions482in the sheet width direction Dw are wider than widths Rw of the roller portions482. In the two suction rollers48disposed adjacent to each other in the sheet conveyance direction Dc, between adjacent ones of the roller portions482of one of the suction rollers48in the sheet width direction Dw, the roller portions482of the other of the suction rollers48are located.

According to this structure, it is possible to alternately arrange the roller portions482of one and the other of the two suction rollers48in the sheet width direction Dw, and to secure some space between the roller portions of one and the other of the two suction rollers48. Thereby, it is possible to achieve improved sheet conveyance performance, and further to suppress excessive rise in suction resistance due to the exhaust fan8.

Further, the inkjet recording apparatus1includes a plate portion9shown inFIGS.3and4. The plate portion9is disposed opposite such part of the sheet conveyance surface of the first conveyance belt411as is located, in the sheet conveyance direction Dc, upstream of the recording portion5but downstream of the suction roller47. In other words, the plate portion9is disposed above an upstream part of the housing461in the sheet conveyance direction Dc, with the first conveyance belt411therebetween. The plate portion9is disposed above the first conveyance belt411at a predetermined interval therefrom.

The plate portion9extends in the sheet conveyance direction Dc and in the sheet width direction Dw. The plate portion9extends in parallel with the sheet conveyance surface of the first conveyance belt411, for example.

According to the above structure, it is possible to narrow an air flow path over the first conveyance belt411, in the vicinity of the sheet conveyance surface. Accordingly, it is possible to increase speed of the air flows generated by the exhaust fan8, and thus to effectively remove paper dust generated from a sheet S.

The plate portion9extends in the sheet conveyance direction Dc and the sheet width direction Dw, over an entire region between the recording portion5and the suction roller47, for example. According to this structure, it is possible to further increase the speed of the air flows generated by the exhaust fan8, and thus to further improve the effect of removing paper dust generated from a sheet S.

The above-described embodiments are by no means meant to limit the scope of the present disclosure, and various modifications can be made and implemented within the scope not departing from the gist of the present disclosure.