Liquid ejection apparatus

A first common tangent of a first pulley and a second pulley is in parallel with the scanning direction. A second external common tangent of the first pulley and a third pulley intersects with the scanning direction. A motor has a shaft extended in a first direction and connected to the third pulley. An endless belt is wound on the first, second, and third pulleys. A belt connecting portion is provided on the carriage and connected to the belt in a portion on the first external common tangent. The distance between the head passing region and the third pulley is greater than a radial difference obtained as the length of the radius of the motor minus the radius of the third pulley. The distance between the head passing region and the belt connecting portion is smaller than the radial difference.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent Application No. 2012-014131, which was filed on Jan. 26, 2012, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to liquid ejection apparatuses which eject liquid.

2. Description of the Related Art

Inkjet printers are available in which a carriage mounting an inkjet head is connected to a portion extended in a scanning direction of a timing belt wound around a pair of pulleys separated from each other in the scanning direction, and in which a motor shaft is connected to one of the pulleys.

SUMMARY OF THE INVENTION

In this type of inkjet printer, the distance between the pulley and the inkjet head, and the distance between the inkjet head and the motor connected to the pulley via the motor shaft become smaller as the distance between the inkjet head and the carriage belt connecting portion connected to the belt becomes smaller in an orthogonal direction orthogonal to the scanning direction and an axial direction of the motor shaft. Further, the distance between the belt connecting portion and the inkjet head becomes greater as the distance between the inkjet head and the motor and the distance between the inkjet head and the pulley connected to the motor shaft increase in the orthogonal direction. It is therefore not possible to suppress rattling of the carriage by reducing the distance between the belt connecting portion and the inkjet head where the center of gravity of the carriage is located, and at the same time avoid the interference between the motor and the inkjet head by increasing the distance between the motor and the inkjet head and widening the moving range of the carriage.

It is accordingly an object of the present invention to provide a liquid ejection apparatus in which the belt connecting portion of the carriage can be brought close to the inkjet head while providing a wide moving range for the carriage.

The present invention provides a liquid ejection apparatus which includes: a liquid ejection head configured to eject liquid; a carriage adapted to hold the liquid ejection head and movable in a predetermined scanning direction; a first pulley and a second pulley disposed in a housing of the apparatus and separated from each other in the scanning direction, and a first common tangent of the first and second pulleys being in parallel with the scanning direction a third pulley disposed in the housing, and a second external common tangent of the first and third pulleys intersecting with the scanning direction; a motor having a rotatable shaft extended in a first direction and a larger diameter than the third pulley, the shaft being directly connected to the third pulley; an endless belt wound around the first pulley, the second pulley, and the third pulley as to circumscribe the first pulley, the second pulley, and the third pulley; and a belt connecting portion provided on the carriage and connected to the belt in a portion on the first external common tangent; the center of gravity of the carriage including the liquid ejection head being positioned as to overlap the liquid ejection head in the first direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described below. In the following, the right side and the left side of the scanning direction are defined as shown inFIG. 1. Further, inFIG. 1, the direction perpendicular to the plane of the paper is the vertical direction, and the directions upward and downward of the vertical direction are directions out of the plane of the paper and into the plane of the paper, respectively.

As illustrated inFIG. 1, a printer1as a liquid ejection apparatus according to the present embodiment includes a carriage2, an inkjet head3as a liquid ejection head, and a sheet feeding rollers4, and so on. The carriage2is made from materials such as a synthetic resin material, and is movable in the scanning direction along two guide rails5and6provided in a printer main body1a. The carriage2reciprocates along the scanning direction upon driving a movement mechanism11which is described later. In the present embodiment, the printer main body1a, including the guide rails5and6, corresponds to the housing of the present invention.

The inkjet head3is held on the carriage2, and ejects ink through a plurality of nozzles10formed on the bottom surface of the inkjet head3. The inkjet head3includes a plurality of plates made of metallic material and laminated to form ink channels, and is therefore heavier than the other parts of the carriage2. Accordingly, the center of gravity of the carriage2holding the inkjet head3overlaps substantially the central portion of the inkjet head3in the vertical direction representing the first direction in parallel with the axial direction of a shaft24awhich is described later. In the following, descriptions will be given through the case where the center of gravity of the carriage2is the center of gravity of the carriage2including the inkjet head3. As used herein, “overlapping in the vertical direction” means overlapping when projected onto a plane orthogonal to the vertical direction. The same is the case for the scanning direction and the sheet feeding direction to be described later. The sheet feeding rollers4feed record sheet P in the sheet feeding direction as a second direction orthogonal to the scanning direction and the vertical direction.

In the printer1, the record sheet P is printed as the inkjet head3reciprocating along the scanning direction with the carriage2ejects ink onto the record sheet P fed in the sheet feeding direction by the sheet feeding rollers4. The sheet feeding rollers4discharge the record sheet P after the printing.

The following describes the detailed configurations of the carriage2, the guide rails5and6, and the movement mechanism11provided to move the carriage2, with reference toFIGS. 2 to 6. For clarity, the internal configuration of the carriage2other than the inkjet head3, a belt grip2a, and sliding portions2b1and2b2is not shown inFIG. 5.

The guide rails5and6are formed from substantially rectangular plate-like members of metal or some other material extending lengthwise along the scanning direction in planar view. The plate-like members are formed into the guide rails5and6by being bent at the both end portions in the sheet feeding direction. More specifically, the guide rail5is bent upward at the both end portions in the sheet feeding direction, and outward of the bent portions in the sheet feeding direction. The guide rail5at substantially the center of the sheet feeding direction supports the bottom of the carriage2at the end portion on the upstream side of the sheet feeding direction.

The guide rail6is bent upward at the end portion on the upstream side of the sheet feeding direction. The guide rail6is also bent upward at the end portion on the downstream side of the sheet feeding direction, and outward of the bent portion in the sheet feeding direction. The guide rail6has a sliding surface6a1which extends along the scanning direction. The sliding surface6a1is the upper end portion of the vertically extending surface on the downstream side of the sheet feeding direction at the end portion of the guide rail6bent on the upstream side of the sheet feeding direction. The guide rail6also has a sliding surface6a2which extends along the scanning direction. The sliding surface6a2is the vertically extending surface on the upstream side of the sheet feeding direction at the end portion of the guide rail6bent on the downstream side of the sheet feeding direction.

The carriage2has sliding portions2b1and2b2for the sliding surfaces6a1and6a2, respectively. The sliding portion2b1is in contact with the sliding surface6a1from the downstream side of the sheet feeding direction. The sliding portion2b2is in contact with the sliding surface6a2from the upstream side of the sheet feeding direction. The carriage2can move along the scanning direction as the sliding portions2b1and2b2slide on the sliding surfaces6a1and6a2, respectively, while being restricted from rotating on the horizontal plane, specifically in directions about the axis of the shaft24a, which is described later. Grease is applied to the sliding surfaces6a1and6a2for smooth sliding with the sliding portions2b1and2b2.

The inkjet head3held on the carriage2is positioned between the guide rail5and the guide rail6, except for the end portion on the downstream side of the sheet feeding direction. The end portion on the downstream side of the sheet feeding direction overlaps the sliding surface6a1in the vertical direction. In the present embodiment, the sliding surface6a1corresponds to the sliding surface of the present invention.

The movement mechanism11includes three pulleys21to23, a motor24, a belt25, a pulley26, and a pulley holder27, and so on.

The pulley21as a first pulley is fixed to the right end portion on the top surface of the guide rail6. The pulley22as a second pulley is a pulley having substantially the same diameter as the pulley21, and is fixed to the left end portion on the top surface of the guide rail6. Specifically, the pulley21and the pulley22are separated from each other in the scanning direction. The pulley21and the pulley22have the same position in the sheet feeding direction, and the first external common tangent L1of the pulleys21and22on the upstream side of the sheet feeding direction is parallel to the scanning direction.

The pulley23as a third pulley is a toothed pulley, and is fixed to the top surface of the guide rail6at a position offset from the pulley21on the downstream side of the sheet feeding direction. The pulley23is thus disposed at such a position that the second external common tangent L2of the pulley21and the pulley23intersects with the scanning direction. The pulleys21and22may be toothed pulleys as is the pulley23, or may be toothless pulleys unlike the pulley23. The pulley23may be a toothless pulley.

The motor24is disposed below the guide rail6, and the shaft24arotatably provided for the motor24is directly connected to the pulley23. Here, the motor24disposed below the guide rail6is connected to the pulley23as the shaft24ais drawn above the guide rail6through a through hole6bformed through the guide rail6at the portion opposite the pulley23. The radius Rm of the motor24is larger than the radius Rp of the pulley23. The upper end portion of the housing of the motor24is above the bottom surface of the inkjet head3. Accordingly, the upper end portion of the motor24has the same height as a head passing region A1which is described later. In other words, the upper end portion of the motor24has the same vertical position as the head passing region A1.

The belt25is an endless belt, and is wound around the pulleys21to23as to circumscribe the pulleys21to23. A belt grip2a, a belt connecting portion provided on the carriage2, is connected to the belt25wound around the pulleys21to23, at a portion25aon the first external common tangent L1. In this way, the carriage2is fixed to the belt25. Further, the belt grip2ais disposed between the ink ejection head3and the pulley23in the sheet feeding direction.

The belt25is a toothed belt with a plurality of teeth formed along the inner circumference (not illustrated), and the teeth of the belt25are in engagement with the teeth of the pulley23. In this way, driving the motor24and rotating the shaft24aand the pulley23connected to the shaft24arotates the belt25, which, in turn, rotates the pulleys21and22. Rotating the belt25moves the portion25ain the scanning direction. As a result, the carriage2, connected to the portion25a, moves in the scanning direction over a maximum travel range W. The inkjet head3passes through the head passing region A1as the carriage2moves over the maximum travel range W.

The pulley26as a fourth pulley is disposed on the top surface of the guide rail6, in proximity to the pulleys21and23on the left side thereof and between the pulleys21and23in the sheet feeding direction. The internal common tangent L3, which is the internal common tangent of the pulleys22and pulley26and in contact with the pulley22on the opposite side from the first external common tangent L1, is substantially parallel to the scanning direction. The pulley26is in contact with a contact portion25b1located on the outer surface of the portion25bof the belt25between the pulleys22and23, and bends the portion25bof the belt25. Bending the portion25bof the belt25in this fashion creates a portion25b2between the contact portion25b1and the pulley22, substantially in parallel with the scanning direction, and a portion25b3between the contact portion25b1and the pulley23, substantially in parallel with the sheet feeding direction.

The pulley holder27is provided to hold the pulley26, and is supported by the guide rail6so as to be movable in the scanning direction. Further, the pulley holder27is urged rightward by a torsion spring42, and moves in the scanning direction to the point where the force urged by the torsion spring42balances the tension on the belt25. In this way, the tension on the belt25is adjusted to the magnitude which corresponds to the force urged by the torsion spring42. The pulley holder27is fixed to the guide rail6with a bolt41at the position where the force urged by the torsion spring42balances the tension on the belt25. In this manner, the four pulleys21to23, and26are all fixed in position in the present embodiment.

The positional relationships between the members of the printer1are described below in greater detail.

In the printer1, the pulley23is disposed at a position offset from the pulley21on the downstream side of the sheet feeding direction, as described above. More specifically, the distance D11between the head passing region A1and the pulley23in the second direction, which is in parallel with the sheet feeding direction, is greater than the radial difference Rs, which is the length of the radius Rm of the motor24minus the radius Rp of the pulley23(Rs=Rm−Rp).

The pulley23is described below in more detail with regard to its position in the scanning direction. The pulley23is disposed within the both ends of the maximum travel range W of the carriage2in the scanning direction, and at a position at which the distance D12between the pulley23and the right end of the maximum travel range W in the scanning direction is equal to or greater than the radial difference Rs. Because the pulley23is disposed at the right end portion of the guide rail6, the distance D13between the pulley and the left end of the maximum travel range W in the scanning direction is evidently greater than the distance D12. Accordingly, the distance D13is greater than the radial difference Rs, as with the case of the distance D12.

The distance D14between the belt grip2aand the head passing region in the second direction, which is in parallel with the sheet feeding direction, is smaller than the radial difference Rs.

The vertical positional relationships are described below. The pulleys21to23are positioned below the sliding surface6a1and the sliding portion2b1of the carriage2. Accordingly, the belt25wound around the pulleys21to23is also positioned below the sliding surface6a1and the sliding portion2b1, specifically a position offset from the sliding surface6a1in the vertical direction.

The pulley26bends the portion25bof the belt25between the pulley22and the pulley23. This creates a space S which extends in the scanning direction over the top surface of the guide rail6, downstream of the portion25b2of the belt25in the sheet feeding direction and upstream of the axis of the pulley23in the sheet feeding direction. Specifically, the space S extends in the scanning direction over the top surface of the guide rail6at a position between the portion25b2and the plane which passes through the axis of the pulley23and is in parallel with the scanning direction.

An encoder film43and a protective film44are disposed in the space S. The encoder film43is a film extending along the scanning direction. The right and left end portions of the encoder film43are attached to film attaching portion51and52, respectively, provided on the top surface of the guide rail6. The left end portion of the encoder film43attached to the film attaching portion51and52is pulled leftward by a torsion spring53provided on the top surface of the guide rail6. The encoder film43thus extends in the scanning direction without a slack.

The encoder film43has a plurality of slits (not illustrated) formed along the scanning direction. The carriage2, on the other hand, is provided with a position detecting element12in a portion opposite from the surface of the encoder film43on the downstream side of the sheet feeding direction. The position detecting element12is provided to detect the slits of the encoder film43and detect the position of the carriage2. In the present embodiment, the encoder film43and the position detecting element12together correspond to the encoder of the present invention.

The protective film44is a film extending along the scanning direction, and is disposed between the encoder film43and the portion25b2of the belt25. The both end portions of the protective film44in the scanning direction are attached to portions of the film attaching portion51and52, respectively, on the upstream side of the encoder film43in the sheet feeding direction. The right end portion of the protective film44attached to the film mounts51and52is pulled rightward by a torsion spring54provided on the top surface of the guide rail6. The protective film44thus extends in the scanning direction without a slack. The protective film44prevents the portion25b2of the belt25from contacting the encoder film43.

Here, assume that, unlike the present embodiment, the pulleys23and26are not provided, and the belt25is wound around the pulleys21and22with the shaft24aof the motor24being directly connected to the pulley21, as described above. In this case, the motor24, which overlaps the head passing region A1in the sheet feeding direction as described above, also overlaps the head passing region A1in the scanning direction, as indicated by dashed-two dotted lines inFIG. 6, when the belt grip2ais where the distance D14becomes smaller than the radial difference Rs. Specifically, the distance D11becomes equal to or less than the radial difference Rs.

As such, the inkjet head3and motor24interfere if the carriage2is moved over the maximum travel range W and the inkjet head3passes over the head passing region A1as in the present embodiment. Avoiding such interference between the inkjet head3and the motor24requires the right end of the moving range of the carriage2to be more toward the left and narrowing the maximum travel range W than in the present embodiment, so that the motor24and the head passing region do not overlap each other in the sheet feeding direction.

On the other hand, the belt grip2awould be disposed more downstream of the sheet feeding direction than in the present embodiment and the distance D14would become equal to or greater than the radial difference Rs if the motor24were disposed where it does not overlap the head passing region A1in the scanning and the sheet feeding direction, specifically a position where the distance D11becomes equal to or greater than the radial difference Rs, in order to move the carriage2over the maximum travel range W. As a result, the belt grip2awill be far distant apart from the center of gravity of the carriage2when the motor24has a large radius Rm, and the carriage2may rattle heavily when the belt25is rotated to accelerate and move the carriage2in the scanning direction.

For these reasons, the configuration in which the shaft24aof the motor24is directly connected to either of the pulleys21and22fails to increase the maximum travel range W by making the distance D11greater than the radial difference Rs, and at the same time to bring the belt grip2acloser to the center of gravity of the carriage2by making the distance D14smaller than the radial difference Rs.

On the other hand, in the printer1of the present embodiment, the motor24is mounted on the pulley23different from the pulleys21and22. It is therefore possible to adjust the positional relationships between the pulleys21and22and the pulley23in a manner allowing the pulley23to be offset from the pulleys21and22on the downstream side of the sheet feeding direction by a distance which corresponds to the radius Rm of the motor24and the radius of the pulley23. In this way, the distance D14can be made smaller than the radial difference Rs while making the distance D11greater than the radial difference Rs.

Because the distance D11is greater than the radial difference Rs, the motor24does not overlap the head passing region A1in the scanning direction. Accordingly, there will be no interference between the inkjet head3and the motor24, regardless of how far the inkjet head3moves in the scanning direction. The maximum travel range W of the carriage2can thus be increased as a result.

The distance D14is smaller than the radial difference Rs. Accordingly, the belt grip2ais disposed at a position close to the inkjet head3, specifically the center of gravity of the carriage2, regardless of the radius Rm of the motor24. This makes it possible to suppress the rattling of the carriage2upon rotating the belt25and accelerating and moving the carriage2in the scanning direction.

In the present embodiment, the belt grip2acan thus be brought close to the center of gravity of the carriage2while increasing the maximum travel range W.

Further, in the present embodiment, the pulley23is positioned within the both ends of the maximum travel range W of the carriage2in the scanning direction, and the distances D12and D13are equal to or greater than the radial difference Rs. The motor24thus does not protrude from the maximum travel range W in the scanning direction. It is therefore not required to increase the size of the printer1in the scanning direction to dispose the motor24, making it possible to miniaturize the printer1.

Further, in the printer1, the portion25aof the belt25where the belt grip2ais connected is disposed downstream, in the sheet feeding direction, of the sliding surface6a1provided at the end of the guide rail6on the upstream side of the sheet feeding direction, specifically at a position distant apart from the center of gravity of the carriage2. However, in the present embodiment, the sliding surface6a1vertically overlaps the end portion of the inkjet head3on the downstream side of the sheet feeding direction, as described above. This enables the portion25aof the belt25disposed opposite from the inkjet head3over the sliding surface6a1, and the belt grip2aconnected to the portion25ato be disposed closer to the center of gravity of the carriage2than when the sliding surface6a1is disposed downstream of the inkjet head3in the sheet feeding direction.

Further in the present embodiment, the belt25is disposed below the sliding surface6a1, even though the portion25aof the belt25is in proximity to the sliding surface6a1on the downstream side of the sheet feeding direction. In this way, the grease applied to the sliding surface6a1does not touch the belt25even when the portion25aof the belt25momentarily bends toward the sliding surface6a1.

Further, in the present embodiment, the tension pulley26bends the belt25at the portion25bbetween the pulley22and the pulley23. This creates the space S which extends in the scanning direction downstream of the portion25b2of the belt25in the sheet feeding direction and upstream of the pulley23in the sheet feeding direction. The encoder film43and the protective film44, extending in the scanning direction, are disposed in the space S. The printer1can thus be reduced in size by making effective use of the space S in this fashion.

Further, because the portion25bof the belt25is bent by the pulley26, the portion25b2is disposed more upstream of where it would have been when the portion25bwas not bent by the pulley26, specifically closer to the portion25awhere the belt grip2ais connected. Accordingly, the encoder film43disposed in the space S in proximity to the portion25b2of the belt25on the downstream side in the sheet feeding direction is also disposed close to the portion25aof the belt25, and is not easily affected by the accidental posture change of the carriage2during the travel. The position of the carriage2can thus be accurately detected by detecting the slits of the encoder film43with the position detecting element12.

Further, in the present embodiment, the encoder film43is disposed downstream of the portion25aof the belt25in the sheet feeding direction where the belt grip2ais connected, specifically opposite from the inkjet head3over the portion25a. Thus, the encoder film43can be disposed without increasing the distance between the belt grip2aand the inkjet head3in the sheet feeding direction.

Further, in the present embodiment, the pulley26bends the portion25bof the belt25, as described above. Accordingly, the wind angle of the belt25for the pulley23is larger than when the portion25bis not bent by the pulley26. This ensures that the power from the pulley23is reliably transmitted to the belt25without causing defects such as jumping.

Further, in the present embodiment, the central axis positions of the pulleys21to23and the pulley26are all fixed to the guide rail6. The tension of the belt25can thus be fixed at the assembly tension. Further, with the pulleys21to23and26fixed, jumping of the belt25can be prevented without providing an excessively large tension for the belt25. It is therefore possible to reduce the tension on the belt25and thus the frictional resistance between the pulleys21to23and their rotational axes, or between the rotational axes of the pulleys21to23and the bearings. The load on the motor24can thus be reduced.

Modifications of the present embodiment are described below. In the following, descriptions concerning the configurations already described in the embodiment above are omitted as appropriate.

In the foregoing embodiment, the pulley23connected to the shaft24aof the motor24is disposed within the both ends of the maximum travel range W of the carriage2in the scanning direction, and the distances D12and D13are equal to or greater than the radial difference Rs. As a result, the motor24does not protrude out of the maximum travel range W in the scanning direction. However, the present invention is not limited to this.

For example, as illustrated inFIG. 7, the pulley23may be positioned within the both ends of the maximum travel range W of the carriage2in the scanning direction, and the distance D22between the pulley23and the right end of the maximum travel range W in the scanning direction may be greater than the radial difference Rs to partially protrude the motor24rightward of the maximum travel range W (modification 1).

Further, the pulley23is not necessarily required to be disposed within the both ends of the maximum travel range W of the carriage2in the scanning direction. Specifically, the pulley23may protrude out of the maximum travel range W in the scanning direction either partially or entirely, provided that the motor24overlaps the head passing region A1in the sheet feeding direction.

The foregoing embodiment described the case where the encoder film43and the protective film44are disposed in the space S created downstream of the portion25b2of the belt25in the sheet feeding direction. However, the present invention is not limited to this. Specifically, other components of the printer1may be disposed in the space S, or nothing may be disposed in the space S.

The foregoing embodiment described the case where the pulley26bends the portion25bof the belt25to create the space S downstream of the horizontally extending portion25b2of the belt25in the sheet feeding direction. However, the present invention is not limited to this. For example, as illustrated inFIG. 8, the pulley26may not be provided, and the belt25may be wound around the pulleys21to23(modification 2).

The foregoing embodiment described the case where the pulleys21to23, and the pulley26are all fixed to the guide rail6to fix the tension of the belt25at the assembly tension. However, the present invention is not limited to this.

For example, the pulley holder27urged by the torsion spring42may not be fixed to the guide rail6, and the pulley26may be movable in the scanning direction. In this case, the pulley holder27moves in the scanning direction as to balance the tension on the belt25and the force urged by the torsion spring42.

The foregoing embodiment described the case where the pulley26movable in the scanning direction with the pulley holder27is provided to adjust the tension on the belt25. However, the present invention is not limited to this. Either the pulley21or the pulley22may be movable in the scanning direction to adjust the tension on the belt25. Alternatively, the pulley23may be movable in the sheet feeding direction to adjust the tension on the belt25.

The foregoing embodiment described the case where the belt25is disposed below the sliding surface6a1. However, the present invention is not limited to this. For example, the belt25may be disposed above the sliding surface6a1. It is also possible in this case to prevent the grease applied to the sliding surface6a1from touching the belt25. Further, the belt25may be disposed at the same height as the sliding surface6a1.

The foregoing embodiment described the case where the end portion of the inkjet head3on the downstream side of the sheet feeding direction vertically overlaps the sliding surface6a1. However, the present invention is not limited to this. For example, as illustrated inFIG. 9, the inkjet head3may have a shorter length in the sheet feeding direction, and the inkjet head3as a whole may be disposed upstream of the sliding surface6a1in the sheet feeding direction. Specifically, the inkjet head3is not required to vertically overlap the sliding surface6a1(modification 3).

The foregoing embodiment described the case where the sliding surface6a1is the surface on the downstream side of the vertically extending bent portion of the guide rail6in the sheet feeding direction at the end portion of the guide rail6on the upstream side of the sheet feeding direction. The sliding portion2b1of the carriage2is in contact with the sliding surface6a1from the downstream side in the sheet feeding direction. However, the present invention is not limited to this. For example, the sliding surface may be the surface on the upstream side of the vertically extending portion of the guide rail6in the sheet feeding direction, and the carriage2may be provided with a sliding portion which slides on this sliding surface from the upstream side in the sheet feeding direction.

In this case, the carriage2does not have the sliding portion between the portion25aof the belt25and the sliding surface6a1, and the portion25aof the belt25can be disposed even closer to the sliding surface6a1. As a result, the belt grip2acan be brought closer to the center of gravity of the carriage2.

The foregoing embodiment described the case where the belt grip2ais disposed downstream of the inkjet head3in the sheet feeding direction. However, the present invention is not limited to this. For example, as illustrated inFIG. 10, the inkjet head3may have a longer length in the sheet feeding direction, and the belt grip2aand the inkjet head3may vertically overlap each other (modification 4). Specifically, the distance between the inkjet head and the belt grip2ain the direction parallel to the sheet feeding direction may be zero, provided that the distance is shorter than the radial difference Rs.

In the foregoing example, the first direction is in parallel with the vertical direction orthogonal to the scanning direction and the sheet feeding direction. However, the present invention is not limited to this.

For example, in one modification (modification 5), as illustrated inFIGS. 11A and 11B, the axial directions of the pulleys21to23and26, and the axial direction of the shaft24aof the motor24are in parallel with the sheet feeding direction. Specifically, the first direction is in parallel with the sheet feeding direction. The pulley23is disposed above the pulley21, separately therefrom. Further, the distance D31between the pulley23and the head passing region A2of the inkjet head3in the vertical direction is greater than the radial difference Rs. The distance D32between the belt grip2aand the pulley23in the vertical direction is smaller than the radial difference Rs. In this case, the vertical direction corresponds to the first direction of the present invention.

In another modification (modification 6), as illustrated inFIGS. 12A and 12B, the axes of the pulleys21to23and26, and the axis of the shaft24aof the motor24are tilted with respect to the vertical direction. Specifically, the first direction is tilted with respect to the vertical direction. Accordingly, the axes of the pulleys21to23and26, and the axis of the shaft24aof the motor24are directed more upstream in the sheet feeding direction toward the upper end. Further, the pulley23is separated from the pulley21on the opposite side from the inkjet head3in the second direction orthogonal to the first direction and the scanning direction. Further, the distance D41between the pulley23and the head passing region A3of the inkjet head3in the second direction is greater than the radial difference Rs. The distance D42between the belt grip2aand the pulley23in the second direction is smaller than the radial difference Rs.

In the printers represented by modifications5and6, the end portion of the motor24on the shaft24aside in the first direction overlaps the head passing region A2and A3in the second direction. Thus, if the shaft24aof the motor24were connected to the pulley21or22, it would not be possible to make the distances D31and D41greater than the radial difference Rs and increase the moving range of the carriage2, and at the same time to make the distances D32and D42smaller than the radial difference Rs to bring the belt grip2acloser to the inkjet head3in the manner described in the foregoing embodiment.

In modifications5and6, however, the shaft24aof the motor24is connected to the pulley23different from the pulleys21and22, as in the foregoing embodiment. Thus, the positional relationships between the pulleys21and22and the pulley23can be adjusted according to the radius Rm of the motor24, and the radius Rp of the pulley23. In this way, the distances D32and D42can be made smaller than the radial difference Rs while making the distances D31and D41greater than the radial difference Rs. This makes it possible to bring the belt grip closer to the inkjet head3while widening the moving range of the carriage2.

The present invention has been described through the case of the printer which records an image on record sheet by ejecting ink. However, the present invention is not limited to this example, and is also applicable to liquid ejection apparatuses, other than printers, which eject liquid other than ink.