Image forming apparatus

An image forming apparatus including an image forming unit, a conveyor, and a string-shaped regulation member. The image forming unit forms an image on a recording medium. The conveyor is disposed opposing the image forming unit to convey the recording medium along a conveyance passage. The string-shaped regulation member is disposed between the image forming unit and the conveyance passage to regulate a distance between the recording medium and the image forming unit within a certain range.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is based on and claims priority pursuant to 35 U.S.C. §119(a) to Japanese Patent Application Nos. 2013-170042, filed on Aug. 20, 2013, 2013-170101, filed on Aug. 20, 2013, and 2014-115176, filed on Jun. 3, 2014, in the Japan Patent Office, the entire disclosure of each of which is hereby incorporated by reference herein.

BACKGROUND

1. Technical Field

Embodiments of this disclosure relate to an age forming apparatus.

2. Description of the Related Art

As an image forming apparatus such as a printer, a facsimile, a copier, a plotter, and a multifunctional device thereof, for example, an inkjet recording apparatus such as a liquid ejection recording type image forming apparatus is known which includes a recording head configured as a liquid ejection head (a droplet ejection head) ejecting an ink droplet. In such an image forming apparatus, for example, a configuration is known in which a recording medium is guided by a platen member while opposing an image forming unit and a guide member guiding the recording medium conveyed on the platen member and a sheet pressing member pressing a sheet are disposed so as to be movable in a direction perpendicular to a medium conveyance direction.

Particularly, in the case where an image is formed by the liquid ejection recording type, there is a need to maintain a narrow gap of, e.g., about 1 mm between the recording medium and a recording head configured as a liquid ejection head. For that reason, in the case where a regulation member (the guide member and the sheet pressing member) which presses the recording medium is disposed between the recording head and the platen member, there is a need to decrease the thickness of the regulation member.

BRIEF SUMMARY

In at least one embodiment of this disclosure, there is provided an image forming apparatus including an image forming unit, a conveyor, and a string-shaped regulation member. The image forming unit forms an image on a recording medium. The conveyor disposed opposing the image forming unit to convey the recording medium along a conveyance passage. The string-shaped regulation member is disposed between the image forming unit and the conveyance passage to regulate a distance between the recording medium and the image forming unit within a certain range.

In at least one embodiment of this disclosure, there is provided an image forming apparatus including an image forming unit, a conveyor, and a regulation member. The image forming unit forms an image on a recording medium. The conveyor is disposed opposing the image forming unit to convey the recording medium along a conveyance passage. The conveyor includes a pair of upstream-side rotary bodies at an upstream side of the image forming unit in a medium conveyance direction of the recording medium and a pair of downstream-side rotary bodies at a downstream side of the image forming unit in the medium conveyance direction. The regulation member is disposed between the image forming unit and the conveyance passage to regulate the recording medium. The regulation member includes an upstream-side support portion at an upstream side of the image forming unit in the medium conveyance direction to support the regulation member at the upstream side and a downstream-side support portion at a downstream side of the image forming unit in the medium conveyance direction to support the regulation member at the downstream side. The regulation member has a portion that is disposed between the pair of upstream-side rotary bodies and the image forming unit and extends in a vertical direction relative to the conveyance passage.

In at least one embodiment of this disclosure, there is provided an image forming apparatus including an image forming unit, a conveyor, and a regulation member. The image forming unit forms an image on a recording medium. The conveyor is disposed opposing the image forming unit to convey the recording medium along a conveyance passage. The conveyor includes a pair of upstream-side rotary bodies at an upstream side of the image forming unit in a medium conveyance direction of the recording medium and a pair of downstream-side rotary bodies at a downstream side of the image forming unit in the medium conveyance direction. The regulation member is disposed between the image forming unit and the conveyance passage to regulate the recording medium, the regulation member including an upstream-side support portion at an upstream side of the image forming unit in the medium conveyance direction to support the regulation member at the upstream side and a downstream-side support portion at a downstream side of the image forming unit in the medium conveyance direction to support the regulation member at the downstream side. The regulation member has a portion that is disposed between the pair of downstream-side rotary bodies and the image forming unit and extends in a vertical direction relative to the conveyance passage.

DETAILED DESCRIPTION OF EMBODIMENTS

For example, in this disclosure, the term “sheet” used herein is not limited to a sheet of paper and includes anything such as OHP (overhead projector) sheet, cloth sheet, glass sheet, or substrate on which ink or other liquid droplets can be attached. In other words, the term “sheet” is used as a generic term including a recording medium, a recorded medium, a recording sheet, and a recording sheet of paper. The terms “image formation”, “recording”, “printing”, “image recording” and “image printing” are used herein as synonyms for one another.

The term “image forming apparatus” refers to an apparatus that ejects liquid on a medium to form an image on the medium. The medium is made of, for example, paper, string, fiber, cloth, leather, metal, plastic, glass, timber, and ceramic. The term “image formation” includes providing not only meaningful images such as characters and figures but meaningless images such as patterns to the medium (in other words, the term “image formation” also includes only causing liquid droplets to land on the medium).

The term “ink” is not limited to “ink” in a narrow sense, unless specified, but is used as a generic term for any types of liquid usable as targets of image formation. For example, the term “ink” includes recording liquid, fixing solution, DNA sample, resist, pattern material, resin, and so on.

The term “image” used herein is not limited to a two-dimensional image and includes, for example, an image applied to a three dimensional object and a three dimensional object itself formed as a three-dimensionally molded image.

In addition, the ejecting direction of liquid is not limited to a vertically downward direction or a horizontal direction, and for example, may be an oblique direction or a vertically upward direction.

An image forming apparatus according to an embodiment of this disclosure is not limited to a serial-type image forming apparatus and, for example, may be a line-head-type image forming apparatus.

An image farming apparatus according to an embodiment of this disclosure will be described with reference toFIG. 1andFIG. 2.FIG. 1is a perspective view illustrating the image forming apparatus, andFIG. 2is a side view illustrating the image forming apparatus.

The image forming apparatus is a serial-type image forming apparatus. A carriage104is supported by a loadless-type guide assembly using a guide member103formed as a plate member stretched between right and left side plates so that the carriage104is movable in a direction (a main scanning direction) perpendicular to a medium conveyance direction (a sub-scanning direction) indicated by arrow D inFIG. 2.

Further, the carriage104is equipped with a recording head111including a liquid ejection head as an image forming unit that ejects, for example, droplets of respective colors of yellow (Y), cyan (C), magenta (M), and black (K).

Ink (liquid) is supplied from an ink cartridge113as a liquid cartridge (a main tank) detachably attached to an apparatus body to the recording head111through a supply tube114.

Meanwhile, a sheet feed cassette101that loads sheets210(seeFIG. 4below) as a recording medium is mounted on a bottom side of the apparatus body. The sheets210inside the sheet feed cassette101are delivered one by one by a sheet feed roller143.

The sheet210which is fed from the sheet feed cassette101is sent to a gap between a conveyance roller151and a pressing roller152through a relay roller144and a conveyance guide plate145. The conveyance roller151and the pressing roller152are a pair of rotary bodies disposed at the upstream side of the image forming unit in the medium conveyance direction D.

Then, the sheet is intermittently conveyed by a conveyance force generated by the conveyance roller151and the pressing roller152while being guided by a rib153aof a platen member153as a conveyance guide member disposed to face the image forming unit.

At this time, when the recording head111is driven in response to an image signal while the carriage104is moved, an ink droplet is ejected to the stopped sheet210to perform a recording operation for one line, and the sheet210is conveyed by a predetermined amount to perform a recording operation for the next line. The recording operation ends when a recording end signal or a signal indicating the state where a tail end of the sheet210reaches a recording area is obtained.

Sheet discharge rollers154and spur rollers155are disposed at the downstream side of the platen member153, and discharge the sheet210having an image formed thereon onto a sheet discharge tray102. The sheet discharge rollers154and the spur rollers155are pairs of rotary bodies disposed at the downstream side of the image forming unit in the medium conveyance direction D.

Next, a first embodiment of this disclosure applied to the image forming apparatus will be described with reference toFIGS. 3 and 4.FIG. 3is a perspective view illustrating a recording section (a printing section) of the first embodiment, andFIG. 4is a plan view illustrating the first embodiment.

As described above, a platen member153forms a conveyance passage160through which the sheet210is conveyed.

Two regulators201which regulate the uplift of the sheet210are provided above the platen member153in the main scanning direction (the carriage moving direction).

The regulator201includes a regulation member204which is formed as a string-shaped member regulating the distance between the sheet210and the image forming unit (the recording head111) within a uniform range and holding members205and206which hold the regulation member204.

The holding members205and206are guide members which support the regulation member204, and also serve as fixation portions which hold the regulation member204while fixing both ends thereof.

The regulation member204is a flexible string-shaped member (here, a “string”), and is held by two holding members205and206while a tension is applied thereto.

The platen member153includes a plurality of ribs153awhich guides the sheet210in a contact state, and the regulation member204is held at a position higher than the ribs153a.

Further, the regulator201is held at a position which does not cause an interference with the carriage104and the recording head111, and hence the regulator201, the carriage104, and the recording head111do not contact each other even when the carriage104scans the upside of the platen member153in order to perform a print operation.

Here, the holding members205and206of the regulator201are held so as to be movable in a direction parallel to the scan direction of the carriage104by a guide rail281. Then, the holding members are moved by a motor through a timing belt284wound around pulleys282and283.

The timing belt284is provided in each of the upstream side and the downstream side of the platen member153in the medium conveyance direction, the upstream-side timing belt284transmits a power to the upstream-side holding member205, and the downstream-side timing belt284transmits a power to the downstream-side holding member206.

The operations of the upstream-side timing belt284and the downstream-side timing belt284are synchronized with each other by a different timing belt, and hence the upstream-side holding member205and the downstream-side holding member206move in a synchronization state.

In this way, when the regulator201including the regulation member204moves in the main scanning direction, the upstream-side and downstream-side holding members205and206are operated in a synchronization state, and hence the regulator may move without any inclination in the scan direction of the carriage104.

Further, in two holding members205connected to the upstream-side timing belt284, the timing belt284having a loop shape is fixed and held by a fixation portion288at a different surface. Similarly, in two holding members206connected to the downstream-side timing belt284, the timing belt284having a loop shape is fixed and held by the fixation portion288at a different surface.

Accordingly, when the timing belt284rotates, two regulators201are respectively operated in the opposite directions in the scan direction of the carriage104. Thus, two regulators201move so as to be symmetrical to each other about the center in the width direction of the platen member153at all times.

When a print operation is performed, a controller reads the size of the sheet210in print information transmitted from a host, and moves the positions of the regulators201so as to match the size of the sheet210in the width direction.

The regulators201are moved so as to be located inside both ends in the width direction perpendicular to the medium conveyance direction of the sheet210conveyed along the platen member153. Thus, when the sheet210is conveyed along the platen member153, the end of the sheet210is nipped between the platen member153and the regulation members204of the regulators201.

The regulation member204of the regulator201may suppress the uplift of the end of the sheet210. That is, for example, even when the sheet210of which the end is easily lifted upward due to the damage and the bending of the sheet210is conveyed, the sheet is regulated at a position where the sheet does not contact the carriage104and the recording head111due to the regulation member204of the regulator201. Thus, it is possible to prevent a failure (for example, a friction, a jam, or the like) caused by the contact of the sheet210with respect to the carriage104and the recording head Ill.

Further, an area where the regulation member204is located between the sheet210and the recording head111becomes an area where a print operation may not be performed on the sheet210.

Therefore, since the thin string-shaped member is used as the regulation member204, the end outside the printable area of the sheet210may be suppressed, and hence the uplift of the sheet may be reduced without decreasing the size of the printable area.

Further, since the regulation member204is formed as the string-shaped member, the regulation member204is bent by the contact with respect to the carriage104, and hence the damage thereof may be prevented compared to a thin and flexible member such as Mylar having a uniform width.

Further, in a flat member such as mylar, when a deviation occurs in the width direction of the fixation member (the holding member) at the downstream side and the upstream side in the medium conveyance direction, the regulation member is twisted, and the regulation member is lifted upward. For that reason, there is a need to accurately synchronize the movement of the fixation members at the downstream side and the upstream side in the medium conveyance direction.

On the contrary, since the regulation member204is the string-shaped member, the regulation member204is not twisted even when a slight deviation occurs in the synchronization of the fixation member (the holding member). For this reason, there is no need to precisely synchronize the movement of the fixation members, and hence the fixation member moves easily.

Next, the regulator of this embodiment will be described in detail with reference toFIGS. 5A and 5B.FIGS. 5A and 5Bare perspective views illustrating the regulator, whereFIG. 5Ais a perspective view including the holding member, andFIG. 5Bis a perspective view illustrating a laid passage of the regulation member except for the holding member.FIGS. 5A and 5Bare perspective views illustrating the regulator.

A leaf spring211is provided inside the upstream-side holding member205, and one end of the regulation member204is held by the holding member205through the leaf spring211. One end of the regulation member204is formed in a loop shape, and is caught and held by a notch formed in the leaf spring211.

Further, the downstream-side holding member206is provided with a fixation member212, and the other end of the regulation member204is held by the holding member206through the fixation member212. The other end of the regulation member204is held in a manner such that the loop-shaped end is caught by a pawl formed in the fixation member212.

Here, since one end of the regulation member204is held by the holding member205through the leaf spring211, the regulation member204is held while a tension is applied thereto. For this reason, the regulation member204is formed of a flexible material, but is held in a tension application state, so that the regulation member is held in a shape along the shapes of the holding members205and206as illustrated inFIG. 13A.

Further, since one end of the regulation member204is held by the leaf spring211, a certain degree of deformation of the regulation member204is allowed.

Here, for example, when the sheet210is stopped on the platen member153due to a certain reason during the print operation, a user needs to remove the sheet210on the platen member153. At this time, since the regulation member204is formed of a flexible material as described above, a certain degree of deformation is allowed. During such clearance, the sheet210stopped on the platen member153may be removed without damaging the regulation member204or the holding members205and206.

Next, the arrangement of the regulator201of this embodiment will be described with reference toFIG. 6.FIG. 6is a side view illustrating the arrangement.

The conveyance roller151and the pressing roller152which sends the sheet210onto the platen member153are provided at the upstream side of the platen member153in the medium conveyance direction D.

The sheet discharge rollers154and the spur rollers155which send the sheet210delivered from the platen member153to the sheet discharge tray102are provided at the downstream side of the platen member153in the medium conveyance direction D.

Here, the pressing roller152is held by the apparatus body through a pressing plate221. Further, the spur rollers155is held by the apparatus body through a spur holder222.

Then, both ends of the regulation member204are respectively held by the upstream-side holding member205provided above the pressing plate221and the downstream-side holding member206provided above the spur holder222.

Thus, the holding members205and206as the guide members are located near the recording head111in relation to the position of the regulation member between the recording head111and the recording medium conveyance passage160. Further, both ends of the regulation member204are disposed through the upside of the pressing roller152and the spur rollers155, that is, the opposite side to the conveyance passage160.

Here, the upstream-side holding member205is movably held by the guide rail281held by the apparatus body. The downstream-side holding member206is movably held by the guide rail281(the rail) provided in the spur holder222held by the apparatus body.

The front ends of the holding members205and206respectively extend from the upper surfaces of the pressing plate221and the spur holder222to the vicinity of the platen member153so as to cover the end near the platen member153.

Then, the flexible regulation member204is disposed so as to pass through a gap between the recording head111and the platen member153on the platen member153along the shapes of the holding members205and206.

When the regulation member204and the holding members205and206are formed in this way, the regulation member204and the holding members205and206are movable to an arbitrary position in the main scanning direction. Further, since these members are disposed at a position where any interference with the recording head111does not occur, the operation of the recording head111is not disturbed during the print operation.

Further, only the regulation member204is disposed between the platen member153and the recording head111. However, since the regulation member204is formed as the string-shaped member, the thickness may be decreased compared to, for example, a regulation member formed as a thin plate such as sheet metal. Accordingly, since an increase in distance between the platen member and the recording head may be suppressed due to the addition of the regulation member, and hence a satisfactory image may be obtained by the liquid ejection recording type.

Furthermore, the holding members205and206as the guide members are located near the recording head111in relation to the position of the regulation member204between the recording head111as the image forming unit and the recording medium conveyance passage160. Thus, the sheet210may be conveyed along the platen member153without causing any interference when the sheet210is conveyed along the platen member153.

Next, a second embodiment of this disclosure will be described with reference toFIGS. 7 and 8.FIG. 7is a perspective view illustrating a recording section (a printing section) of the second embodiment, andFIG. 8is a plan view illustrating the recording section.

In this embodiment, both ends of the regulation member204of the regulator201are respectively fixed and held by holding portions (fixation portions)307and308which are provided in the pressing plate221and the spur holder222and are different from guide members305and306, and the halfway portions thereof are held and guided by the guide members305and306.

Here, the guide members305and306of the regulator201are held so as to be movable in a direction parallel to the scan direction of the carriage104by the guide rail281similarly to the holding members205and206of the first embodiment. Then, the guide members are moved by a motor through the timing belt284wound around the pulleys282and283.

The timing belt284is provided in each of the upstream side and the downstream side of the platen member153in the medium conveyance direction D, the upstream-side timing belt284transmits a power to the upstream-side guide member305, and the downstream-side timing belt284transmits a power to the downstream-side guide member306.

The operations of the upstream-side timing belt284and the downstream-side timing belt284are synchronized with each other by a different timing belt, and hence the upstream-side guide member305and the downstream-side guide member306move in a synchronization state.

In this way, when the regulator201including the regulation member204moves in the main scanning direction, the upstream-side and downstream-side guide members305and306are operated in a synchronization state, and hence the regulator may move without any inclination in the scan direction of the carriage104.

Further, in two guide members305connected to the upstream-side timing belt284, the timing belt284having a loop shape is fixed and held by a fixation portion288at a different surface. Similarly, in two guide members306connected to the downstream-side timing belt284, the timing belt284having a loop shape is fixed and held by the fixation portion288at a different surface.

Accordingly, when the timing belt284rotates, two regulators201are respectively operated in the opposite directions in the scan direction of the carriage104. Thus, two regulators201move so as to be symmetrical to each other about the center in the width direction of the platen member153at all times.

When a print operation is performed, a controller reads the size of the sheet210in print information transmitted from a host, and moves the positions of the regulators201so as to match the size of the sheet210in the width direction.

Next, the regulator201of this embodiment will be described in detail with reference toFIGS. 9A and 9B.FIGS. 9A and 9Bare perspective views illustrating the regulator, whereFIG. 9Ais a perspective view illustrating the guide member, andFIG. 9Bis a perspective view illustrating a laid passage of the regulation member except for the guide member.

One end of the regulation member204is laid in a direction perpendicular to the medium conveyance direction D while the halfway portion thereof is supported by the upstream-side guide member305in the medium conveyance direction D, and the loop-shaped portion formed at the end is caught and held by a projection307formed in the pressing plate221.

The other end of the regulation member204is laid in a direction perpendicular to the medium conveyance direction D while the halfway portion thereof is supported by the downstream-side guide member306in the medium conveyance direction D, and a loop-shaped portion formed in the end is caught and held by a fixation portion308formed in the spur holder222.

In this way, since the end of the regulation member204is held by a member forming the conveyance passage160such as a pressing plate or a spur holder, it is possible to decrease the number of components used for the fixing operation.

Next, regulator movement range will be described with reference toFIGS. 10A and 10B.FIGS. 10A and 10Bare perspective views illustrating the regulator movement range.

The regulation member204of the regulator201and the guide members305and306may handle the maximum-width sheet while moving to a position illustrated inFIG. 10A, and may handle the minimum-width sheet while moving to a position illustrated inFIG. 10B.

Further, when the guide members305and306move due to the sheet size, an area of the regulation member204facing, a printing face also moves. For this reason, a contamination caused by an ink mist does is dispersed without concentrating on a partial position compared to the case where the regulation member204is fixed to the guide member, and hence the product life of the regulation member204may be extended.

Next, a third embodiment of this disclosure will be described with reference toFIGS. 11A and 11B.FIGS. 11A and 11Bare perspective views illustrating a regulator of the third embodiment, whereFIG. 11Ais a perspective view including a guide member, andFIG. 11Bis a perspective view illustrating a laid passage of a regulation member except for the guide member.

In this embodiment, the end of the regulation member204fixed to the spur holder222is fixed by an elastic member310such as a leaf spring. Furthermore, the end fixed to the pressing plate221may be also fixed by an elastic member to a position other than the spur holder222or the position of the spur holder222.

In this way, since at least one end of the regulation member204is fixed by the elastic member, the regulation member204may be deformed by a certain degree.

Thus, it is possible to reduce the damage of the regulation member204during the clearance of the jam as in the first embodiment.

For example, when the sheet210is stopped on the platen member153due to a certain reason during the print operation, the user needs to remove the sheet210on the platen member153. At this time, since the regulation member204is formed of a flexible material and a certain degree of deformation thereof is allowed, it is possible to remove the sheet210stopped on the platen member153without damaging the regulation member204or the guide members305and306during such clearance.

Next, a fourth embodiment of this disclosure will be described with reference toFIG. 12.FIG. 12is a perspective view illustrating a regulator of the fourth embodiment.

In this embodiment, curved portions311and312as laid portions for switching the direction of the regulation member204of the guide members305and306from the medium conveyance direction D to a direction intersecting the medium conveyance direction D are formed in an obtuse angle shape (or a curved surface shape).

Thus, the abrasion of the regulation member204or the guide members305and306may be reduced.

Next, a fifth embodiment of this disclosure will be described with reference toFIG. 13.FIG. 13is a perspective view illustrating a regulator of the fifth embodiment.

In this embodiment, a wiping member313which wipes off the circumferential surface of the regulation member204is disposed in the curved portions311and312which switch the direction of the regulation member204of the guide members305and306from the medium conveyance direction D to a direction intersecting the medium conveyance direction D.

That is, in the case of the liquid ejection type image forming apparatus, a mist or the like easily adheres to the regulation member204. Then, when the sheet210contacts the regulation member204while the mist adheres to the regulation member, the image quality is degraded.

Here, in this embodiment, since both ends of the regulation member204are fixed to a member different from the guide members305and306, the surface of the regulation member204is wiped off by the wiping member313so as to be cleaned by the movement of the guide members305and306. Thus, it is possible to remove a contamination caused by the adherence of the mist, and hence to prevent degradation in print quality.

Next, a sixth embodiment of this disclosure will be described.FIG. 14is a schematic plan view illustrating the sixth embodiment.

In this embodiment, one end of the regulation member204of the regulator201is held by a holding portion410of the pressing plate221. Then, the halfway portion of the regulation member204is supported by the guide member405so that the direction of the regulation member is switched from the main scanning direction to the medium conveyance direction D, and the halfway portion thereof is supported by the guide member406so that the direction thereof is switched from the medium conveyance direction D to the main scanning direction.

Then, the other end of the regulation member204of the regulator201is held by a holding portion411provided in an area other than the main scanning area of the carriage104.

Here, the holding portion411is formed of a reel member around which the regulation member204is wound by a desired amount. When the reel member is rotated in reverse, the regulation member204is loosened.

Thus, when a jam or the like occurs, the jam may be cleared after the regulation member204is loosened.

That is, when the regulation member204is retracted in the event of the jam, there is a concern that the regulation member204may be damaged while being caught by the jammed sheet. Therefore, when the regulation member204is loosened in the event of the jam, the damage of the regulation member204may be prevented.

Further, in this embodiment, since the length of the regulation member204may be changed, the regulation member204may be disposed in an inclined state, for example, in a manner such that the guide member405is moved to the center side and the guide member406is moved to the end side in the main scanning direction. However, in this case, the upstream-side guide member405and the downstream-side guide member406are adapted to be separately driven.

Next, a seventh embodiment of this disclosure will be described with reference toFIGS. 15 to 23.FIG. 15is a perspective view illustrating an appearance of an image forming apparatus according to the seventh embodiment,FIG. 16is a perspective view illustrating a conveyance section of the image forming apparatus,FIG. 17is a cross-sectional side view illustrating the conveyance section,FIG. 18is a perspective view illustrating a platen member as a conveyance guide member,FIG. 19is a plan view illustrating a platen member,FIG. 20is a cross-sectional side view illustrating the platen member, andFIG. 21is a bottom view illustrating the platen member.

In the image forming apparatus, the carriage104equipped with the recording head111as the image forming unit and a conveyance assembly550as a conveyor conveying the sheet210while opposing the recording head111are disposed inside the apparatus body100.

Then, similarly to the image forming apparatus, an image is formed on the sheet210by the recording head111while the sheet210fed from the sheet feed cassette101is conveyed by the conveyance assembly550, and the recording medium having an image formed thereon is discharged to the sheet discharge tray102.

The conveyance assembly550includes a conveyance roller551, a pressing roller552, a platen member553which serves as a conveyance guide member guiding the sheet210while facing the recording head111, a sheet discharge roller554, and a spur555. The platen member553includes a plurality of ribs553ato guide the sheet210.

Then, regulators501including regulation members504are formed as string-shaped members as in the regulation member204disposed between the platen member553and the recording head111as the image forming unit.

The regulator501includes a guide member502which supports the regulation member504at the upstream side and the downstream side of the image forming unit in the medium conveyance direction D, and the guide member502is provided in the platen member553so as to be movable in a direction perpendicular to the medium conveyance direction D.

Here, the guide member502includes an upstream-side holding portion505which supports the regulation member504at the upstream side of the image forming unit in the medium conveyance direction D, a downstream-side holding portion506which supports the regulation member504at the downstream side of the image forming unit in the medium conveyance direction D, and a connecting portion507which connects the upstream-side holding portion505and the downstream-side holding portion506to each other.

Then, the guide member502includes a moving member503which is provided at the opposite side to the recording medium guide side of the platen member553so as to be movable in a direction perpendicular to the medium conveyance direction D.

The moving member503is movably held by a platen rail556fixed to the bottom surfaces (the rear surface in the conveyance passage160) of the platen member553and the platen member553. Furthermore, the platen member553and the platen rail556may be integrally formed with each other by a resin or the like. In this case, the number of components may be decreased.

Then, the connecting portion507of the guide member502is attached to the moving member503.

As a driving assembly which moves the moving member503in the main scanning direction, the bottom surface of the platen rail556is provided with pulleys523and524and a timing belt525wound around the pulleys523and524.

Then, the moving members503of the regulator501are fixed to the different surfaces of the timing belt525by belt clamps526and527, and the right and left moving members503and503are operated in the rotation direction of the single timing belt525so as to move in approaching and separation directions.

Furthermore, the rotation of the timing belt525is performed by a driving motor through a different timing belt or a gear transmission assembly. Further, the timing belt may be replaced by a different belt such as a flat belt or a ring belt, and the belt type is not limited to the timing belt.

Further, the moving member503is provided with a convex portion508, and the convex portion508is detected by an apparatus body side sensor530, so that the position of the moving member503(the position of the regulation member504) is detected.

Here, the guide member502will be described with reference toFIGS. 22 and 23.FIG. 22is a perspective view illustrating a guide member including a regulator, andFIG. 23is a side view illustrating the guide member.

The guide member502includes the upstream-side holding portion505and the downstream-side holding portion506which are uprightly formed in the end of the connecting portion507having a C-shape in a plan view and are curved in the main scanning direction.

Then, the upstream-side holding portion505is provided with a protrusion510which protrudes toward the platen member553so as to determine the height of the regulation member504. The protrusion510includes continuous tapered portions510aand510b.

That is, the protrusion510which protrudes toward the platen member553becomes a portion which first contacts the sheet210compared to the regulation member504when the sheet210is lifted upward. Therefore, since the protrusion510is provided with the tapered portions510aand510b, it is possible to prevent the recording medium from being caught during the conveying operation thereof.

Further, the upstream-side end of the regulation member504is fixed and held by a cutout portion511aprovided in the upstream-side holding portion505, and the downstream-side end thereof is fixed and held by a cutout portion511bprovided in the connecting portion507in the vicinity of the upright portion of the downstream-side holding portion506.

Furthermore, the tapered portions510aand510bare integrally formed with the upstream-side holding portion505, but may be formed separately from each other. Further, the shape of preventing the caught state is not limited to the shape ofFIG. 23.

In this way, since the guide member502that supports the regulation member504at the upstream side and the downstream side in the medium conveyance direction D is provided in the conveyance guide member (the platen member553) so as to be movable in a direction perpendicular to the medium conveyance direction D, it is possible to reduce the positional deviation of the regulation member at the upstream side and the downstream side compared to the configuration in which the upstream-side and downstream-side guide members are separately moved as in the above-described embodiments.

That is, since the guide members are separately provided at the upstream side and the downstream side, a positional deviation may occur in the main scanning direction at the upstream side and the downstream side of the regulation member. For that reason, there is a need to take a large superimposed width (margin) of the regulation member with respect to the end of the recording medium in the width direction in order to prevent the deviation of the regulation member from the end of the recording medium or the adherence of the droplet with respect to the regulation member.

As a result, the printable area of the recording medium decreases. Further, since the driving assembly of the guide member is provided in at least one of the gap between the conveyance roller and the carriage and the gap between the carriage and the sheet discharge roller, the size of the apparatus body increases. Moreover, since the guide member, the guide rail, the driving unit, and the like are respectively provided at the upstream side and the downstream side, the apparatus configuration becomes complicated, and hence the number of components increases.

On the contrary, when one guide member supports (holds) the upstream side and the downstream side of the regulation member and is movable in the main scanning direction as in this embodiment, it is possible to reduce a failure caused when the upstream side and the downstream side are supported by separate guide members.

Next, an eighth embodiment of this disclosure will be described with reference toFIG. 24.FIG. 24is a perspective view illustrating a platen member according to the eighth embodiment.

In this embodiment, an abutting portion541is provided which causes the moving member503to abut against the platen member553.

Then, the reference position of the regulation member504is detected by detecting a change in motor load, which occurs when the moving members503are respectively moved in the arrow direction (by a belt moving in a single direction) to abut against the abutting portion541, through a current value or the like.

Thus, it is possible to omit a sensor for detecting the reference position of the regulation member504.

Next, an example of a control in the use/non-use state of the regulation member504will be described.

For example, when the uplift amount at the end of the recording medium is small at the single face printing and the double face printing with a small ejection amount, the regulation member is not used. Further, even when the regulation member is used at the double face printing, it is possible to decrease the standby time caused by the positioning of the regulation member by the configuration in which the medium width direction result in the case of a print operation performed on a first surface is stored and the regulation member is moved for a medium reversing time up to a print operation performed on a second surface.

Hereinafter, a ninth embodiment of this disclosure will be described with reference toFIG. 25.FIG. 25is a side view illustrating the ninth embodiment.

An image forming apparatus includes a recording head601which is configured as a liquid ejection head such as an image forming unit forming an image on a recording medium (hereinafter, referred to as a “sheet”)610and a conveyor602which opposes the recording head601as the image forming unit and conveys the sheet610.

The conveyor602includes a conveyance roller621and a pressing roller622which serve as a pair of upstream-side rotary bodies disposed at the upstream side of the recording head601in the medium conveyance direction D and includes a sheet discharge roller623and a spur roller624which serve as a pair of downstream-side rotary bodies disposed at the downstream side of the recording head601in the medium conveyance direction.

A platen member603which opposes the recording head601and guides the sheet610is disposed between the pair of the conveyance roller621and the pressing roller622and the pair of the sheet discharge roller623and the spur roller624. The guide surface side of the platen member603forms a conveyance passage660for the sheet610.

Then, a regulation member604which presses the sheet610(to regulate the uplift) is disposed between the recording head601and the platen member603forming the conveyance passage660for the sheet610. The regulation member604is formed of for example, a string-shaped member such as a silk gut line and a thin-layer member such as a PET film.

An upstream-side support portion605which supports the regulation member604at the upstream side of the recording head601in the medium conveyance direction and a downstream-side support portion606which supports the regulation member604at the downstream side of the recording head601in the medium conveyance direction are provided.

The regulation member604includes a portion604awhich approaches to (extends relative to) the conveyance passage660for the sheet610in the vertical direction and is provided between the recording head601and the pair of the conveyance roller621and the pressing roller622as the pair of upstream-side rotary bodies.

Further, the regulation member604includes a portion604bwhich moves away from (extends relative to) the recording medium conveyance passage660in the vertical direction and is provided between the recording head601and the pair of the sheet discharge roller623and the spur roller624as the pair of downstream-side rotary bodies.

Furthermore, in this disclosure, the language that the portion approaches to the recording medium conveyance passage660in the vertical direction indicates that the portion approaches (extends) from a position opposing the conveyance passage660toward the conveyance passage660, and does not necessarily means that the portion approaches to the conveyance passage660in the exactly vertical direction. For example, in this embodiment, the “portion which approaches to the conveyance passage660in the vertical direction” may be the portion which is directed from the upside of the conveyance passage660toward the downside thereof, and is not limited to a portion which is disposed in the vertical direction with respect to the conveyance passage660. Then, a portion which is disposed in an inclined direction with respect to the conveyance passage660is also included. Further, the same applies to the language that the portion moves away from the conveyance passage660.

Then, the regulation member604in the range from the lowest end of the portion604ato the lowest end of the portion604his disposed so as to pass between the recording head601and the platen member603.

In this way, since both ends of the regulation member604in the medium conveyance direction are respectively supported by the upstream-side support portion605and the downstream-side support portion606, the regulation member604may be stably and reliably held at the necessary position between the recording head601and the platen member603.

Thus, since the regulation member604may be formed as a thin member or a string-shaped member, the uplift of the sheet from the conveyance passage660is reduced, the gap between the image forming unit and the sheet is narrowed, and hence a narrow gap may be ensured between the image forming unit and the sheet.

Here, as described above, the regulation member604includes the portion604awhich approaches to the recording medium conveyance passage660in the vertical direction and is provided between the recording head601and the pair of the conveyance roller621and the pressing roller622. Thus, there is no need to widen the gap between the recording head601and the pair of the conveyance roller621and the pressing roller622in order to dispose the regulation member604, and hence the apparatus may be decreased in size.

Further, the regulation member604includes the portion604bwhich moves away from the recording medium conveyance passage660in the vertical direction and is provided between the recording head601and the pair of the sheet discharge roller623and the spur roller624. Thus, there is no need to widen the gap between the recording head601and the pair of the sheet discharge roller623and the spur roller624in order to dispose the regulation member604, and hence the apparatus may be decreased in size.

A tenth embodiment of this disclosure will be described with reference toFIG. 26.FIG. 26is a side view illustrating the tenth embodiment.

This embodiment is different from the ninth embodiment in that the regulation member604includes the portion604awhich approaches to the recording medium conveyance passage660in the vertical direction and is provided between the recording head601and the pair of the conveyance roller621and the pressing roller622, but does not include a downstream-side portion604bwhich moves away from the recording medium conveyance passage660in the vertical direction.

Even in such a configuration, there is no need to widen the gap between the recording head601and the pair of the conveyance roller62land the pressing roller622in order to dispose the regulation member604, and hence the apparatus may be decreased in size.

An eleventh embodiment of this disclosure will be described with reference toFIG. 27.FIG. 27is a side view illustrating the eleventh embodiment.

This embodiment is different from the ninth embodiment in that the regulation member604includes the portion604bwhich moves away from the recording medium conveyance passage660in the vertical direction and is provided between the recording head601and the pair of the sheet discharge roller623and the spur roller624, but does not include an upstream-side portion604awhich approaches to the recording medium conveyance passage660in the vertical direction.

Even in such a configuration, there is no need to widen the gap between the recording head601and the pair of the sheet discharge roller623and the spur roller624in order to dispose the regulation member604, and hence the apparatus may be decreased in size.

Next, a twelfth embodiment of his disclosure will be described with reference toFIGS. 28 and 29.FIG. 28is a side view illustrating the twelfth embodiment, andFIG. 29is a plan view illustrating the twelfth embodiment.

In this embodiment, a driving assembly608as a driving unit is provided which moves the upstream-side support portion605and the downstream-side support portion606in a direction perpendicular to the medium conveyance direction.

The driving assembly608includes a guide rail681which guides the upstream-side support portion605and the downstream-side support portion606, a timing belt684which is wound around pulleys682and683and, a driving source which rotates the pulley682, and the upstream-side support portion605or the downstream-side support portion606is connected to the timing belt684.

Here, each of the upstream-side support portion605and the downstream-side support portion606is disposed at two positions so as to regulate the end of the sheet610in the width direction (the main scanning direction). Then, two upstream-side support portions605are connected to different surfaces of the loop-shaped timing belt684. Similarly, two upstream-side support portions605are connected to different surfaces of the loop-shaped timing belt684.

Thus, two upstream-side support portions605move in a direction moving away from each other by the rotation of the timing belt684in one direction (for example, the direction indicated by arrow A). Further, two upstream-side support portions605move in a direction moving close to each other by the rotation of the timing belt684in the other direction (for example, the direction indicated by arrow B). Further, the same applies to the movement of two downstream-side support portions606.

With such a configuration, when the upstream-side support portion605and the downstream-side support portion606are moved by the driving assembly608, the regulation members604may be moved to a necessary position in response to the width of the sheet610.

Furthermore, the driving assembly may be a feed screw or a ball screw. When such a screw is used, the rotation of the support portions605and606is regulated. Further, a driving source such as a linear motor that directly moves the support portions605and606may be also used.

Here, a clearance of a sheet jam will be described.

As described above, when the sheet jam occurs in the state where the regulation member604is disposed between the conveyance passage660and the recording head601, the regulation member may disturb (cause an interference) when a user performs a jam clearance of removing the sheet610causing the jam in that the sheet610exists between the regulation member604and the platen member603. Further, there is a concern that the regulation member604may be damaged.

Therefore, when the sheet jam is detected due to the occurrence of the sheet jam, e recording head601is moved in a direction moving away from the sheet610or the direction opposite to the direction when the jam does not occur. However, the regulation member604is also moved in the same direction as the recording head601.

Thus, it is possible to prevent the regulation member604from disturbing the jam clearance.

Furthermore, the jam may be detected by a change in voltage value of the moving unit moving the recording head601, a change in speed of the recording head601, or the optical sensor.

Next, a thirteenth embodiment of this disclosure will be described with reference toFIG. 30.FIG. 30is a side view illustrating the thirteenth embodiment.

In this embodiment, the downstream-side support portion606is provided with a tension application member661that applies a tension to the regulation member604. Furthermore, the upstream-side support portion605may be provided with the tension application member661instead of the downstream-side support portion606or along with the downstream-side support portion606.

Since the tension application member661is provided, a tension is reliably applied to the regulation member604, and hence the regulation member604may be held at a necessary position.

Next, a fourteenth embodiment of this disclosure will be described with reference toFIG. 31.FIG. 31is a side view illustrating the fourteenth embodiment.

In this embodiment, a regulation member604A is formed as an elastic member.

Thus, a tension may be obtained by the regulation member604A without providing a separate tension application member as in the thirteenth embodiment.

Next, a fifteenth embodiment of this disclosure will be described with reference toFIGS. 32 and 33.FIG. 32is a side view illustrating the fifteenth embodiment, andFIG. 33is a plan view illustrating the fifteenth embodiment.

In this embodiment, in the configuration of the thirteenth embodiment, the upstream-side support portion605is provided with a tension release member662that releases the tension of the regulation member604. The tension release member662is adapted to be separated when a predetermined amount or more of force is applied to the regulation member604. For example, the tension release member662is fixed to a support portion5through a pawl portion, and the pawl-shaped portion is adapted to be separated by a predetermined amount or more of force.

Further, a tension restoration member663is provided which restores the tension released by the tension release member662.

With such a configuration, when a large force is applied to the regulation member604due to the sheet in the event of the jam, the sheet lifts the regulation member604upward. Thus, when the regulation member collides with (interferes with) the recording head601, the tension of the regulation member604is released by the tension release member662. When the tension of the regulation member604is released, the allowance length of the regulation member604increases.

Since the allowance (the length) of the regulation member604increases due to the release of the tension, the damage of the regulation member604or the degradation in operability for the jam clearance may be prevented.

Further, since the projection of the tension release member662is guided by the tension restoration member663in a manner such that the tension release member662which is separated once moves the regulation member604to the position of the tension restoration member663, the tension may be returned to the tension generation position.

The tension restoration member663is not limited to the guide type, and may be operated by the power of an actuator such as a motor or a solenoid. Further, the tension release member662may not be held by the pawl-shaped portion, and may be held by the other holding unit such as a magnet.

Next, a sixteenth embodiment of this disclosure will be described with reference toFIG. 34.FIG. 34is a side view illustrating the sixteenth embodiment.

In this embodiment, an apparatus body includes therein an image forming section902as an image forming unit, a conveyance assembly905as a conveyor, and the like, and a sheet feed tray904capable of stacking a sheet910as a recording medium thereon is provided at the lower side of the apparatus body. Furthermore, the sheet feed tray904is used as a sheet feed unit while including a sheet feed cassette.

Then, the sheet910fed from the sheet feed tray904is obtained, and the image forming section902records a necessary image by ejecting a droplet in the horizontal direction while the sheet910is intermittently conveyed in the vertical direction by the conveyance assembly905as the conveyor. The sheet910having an image formed thereon is further conveyed upward through a sheet discharge conveyance section906, and is discharged to a sheet discharge tray907as a sheet discharge unit provided at the upper side of the apparatus body.

Here, the image forming section902movably holds a carriage923equipped with a recording head924by a main guide member921and a sub-guide member922. The carriage923moves while performing a scan operation in the main scanning direction through a timing belt stretched between a driving pulley and a driven pulley by a main scanning motor of a carriage moving assembly.

The carriage923is equipped with a recording head924as a liquid ejection head used to eject ink droplets of respective colors of yellow (Y), magenta (M), cyan (C), and black (K).

The recording head924is attached so that the droplet ejecting direction becomes the horizontal direction while nozzle rows each having a plurality of nozzles are arranged in the sub-scanning direction perpendicular to the main scanning direction. That is, employed is a horizontal typing type including the recording head924in which a nozzle face provided with nozzles for ejecting a droplet is disposed in the vertical direction and a droplet is ejected in the horizontal direction.

The sheet910of the sheet feed tray904is separated one by one by a sheet feed roller (semi-lunar roller)943and a separation pad944, and is fed into the apparatus body. The fed sheet910is conveyed to a gap between a pressing roller948and a conveyance belt951of the conveyance assembly905, and is conveyed while being adsorbed to the conveyance belt951.

The conveyance assembly905includes the endless conveyance belt951which is stretched between a conveyance roller952as a driving roller and a driven roller953and a charging roller954which charges the conveyance belt951. Further, the pressing roller948is held by a leading-end pressing plate955. Further, a spur roller958opposing the driven roller953is provided.

The sheet discharge conveyance section906includes a sheet discharge conveyance roller961, a conveyance roller962, a spur roller963, a sheet discharge roller964, a spur roller965, a guide member966, and the like.

Then, in the image forming apparatus, the front surface side of the apparatus body is provided with a front cover801as an openable cover which is openable and closable about a support shaft802. Further, the conveyance belt951, the conveyance roller952, the driven roller953, and the sheet discharge conveyance roller961are integrated with as a conveyance unit700as a conveyance section. Then, the conveyance unit700is provided so as to be openable and closable about the shaft of the conveyance roller952.

Thus, a conveyance passage960may be opened by opening the front cover801and the conveyance unit700.

Even in the image forming apparatus with such a configuration, a regulation member may be provided as in the ninth to sixteenth embodiments.

In this way, in the case of the configuration in which the conveyance passage960is opened in the event of the jam, the pressure of the sheet caused by the jam opens the conveyance unit700, and hence the operation of the regulation member is not needed.

Here, in the case of the jam in which the sheet is tangled by the regulation member, it is desirable that the sheet move in a direction in which the sheet collides with the regulation member (that is, the recording head moving direction) due to the jam.

At this time, in the case where the strength of the regulation member is not strong, there is a possibility that the regulation member may be damaged when the regulation member moves before the conveyance unit is opened, and hence it is desirable to move the regulation member after the conveyance unit is opened.