JP4016922B2 - Belt transport mechanism for ink jet recording apparatus and ink jet recording apparatus provided with the same - Google Patents

Description

  The present invention relates to a belt transport mechanism used for transporting a recording medium in an ink jet recording apparatus that performs recording by ejecting ink onto the recording medium, and an ink jet recording apparatus including the belt transport mechanism.

  An ink jet recording apparatus is an apparatus for forming a desired image thereon by attaching ink ejected from nozzles formed on a head to a sheet. In such an ink jet recording apparatus, a belt conveyance mechanism may be used as a mechanism for conveying a sheet as a recording medium. When the head occupation length in the paper transport direction is long, a roller transport mechanism that transports paper with a plurality of pairs of rollers without using a belt cannot transport relatively short paper. Even such a short sheet can be conveyed.

  On the other hand, in the ink jet recording apparatus, when the state in which ink is not ejected from the nozzles continues for a long time, the surface of the ink meniscus is dried and ink ejection failure occurs. In order to prevent this, it is necessary to periodically perform so-called flushing in which ink is forcibly ejected from the nozzle toward a place other than the paper during non-printing.

  In the case of a serial ink jet recording apparatus in which the head reciprocates in a direction orthogonal to the paper transport direction, flushing can be performed quickly by moving the head to a position off the paper transport path during non-printing. However, in the case of a line-type ink jet recording apparatus in which the head is fixedly arranged along the direction orthogonal to the paper transport direction, for example, when the belt transport mechanism described above is employed as the paper transport mechanism, the belt transport mechanism or the head is retracted. After that, it is necessary to move the member that receives the ink to a position facing the head, which makes the configuration complicated and makes it difficult to perform flushing quickly.

  Therefore, as a technique that enables rapid flushing in a line type ink jet recording apparatus employing a belt conveyance mechanism, an opening is provided in a part of the conveyance belt, and an absorber is positioned at a position facing the head across the conveyance belt. There is a technique in which a recovery mechanism including the ink is disposed, and when the opening of the conveying belt is positioned below the head, ink is discharged toward the opening and the recovery mechanism absorbs the ink (see Patent Documents 1 and 2). .

JP 2001-113690 A (FIGS. 1 and 3) JP 2001-287377 A (FIGS. 1 and 3)

  However, in the above technique, the presence of the opening in the conveyor belt significantly reduces the strength of the conveyor belt, and a desired belt tension cannot be obtained, thereby reducing the sheet conveying function and shortening the life of the conveyor belt. There is a problem.

  An object of the present invention is to provide a belt transport mechanism for an ink jet recording apparatus, which enables rapid flushing with a relatively simple configuration, particularly in a line type ink jet recording apparatus, and reduces the strength of the transport belt, and an ink jet equipped with the same. It is to provide a recording device.

Means and effects for solving the problems

According to an aspect of the present invention, a plurality of rollers, a conveyance belt that is stretched over the plurality of rollers and conveys a recording medium, and the width of the conveyance belt as the conveyance belt runs on the surface of the conveyance belt. A concave portion formed so as to move to at least one of the end portions, and an ink holding member disposed at the width end portion for holding the ink moved in the concave portion, and the transport in the concave portion A belt conveyance mechanism for an ink jet recording apparatus is provided in which the step portion on the upstream side in the running direction of the belt has at least one of the width end portions of the conveyance belt positioned on the upstream side in the running direction from the center of the width. The

  According to the above configuration, quick flushing can be performed with a relatively simple configuration by ejecting ink toward the concave portion without retracting the transport belt or the head. In addition, since no opening is formed in the conveyor belt, a decrease in strength of the conveyor belt can be reduced.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  First, an overall configuration of an ink jet printer (ink jet recording apparatus) including a belt conveyance mechanism according to an embodiment of the present invention will be described with reference to FIG. The ink jet printer 1 according to the present embodiment is a color ink jet printer including four ink jet heads 2. The ink jet printer 1 includes a paper feed unit 11 (left side in the figure) and a paper discharge unit 12 (right side in the figure), and a paper conveyance path that flows from the paper feed unit 11 toward the paper discharge unit 12 is provided inside the apparatus. Is formed.

  A pair of paper feed rollers 5a and 5b are arranged immediately downstream of the paper feed unit 11, and are configured to feed paper as a recording medium from the left to the right in the drawing. Two rollers 6 and 7 and an endless conveyor belt 8 wound around the rollers 6 and 7 are disposed in an intermediate portion of the sheet conveyance path.

  The transport belt 8 has a two-layer structure of a polyester base material impregnated with urethane and silicon rubber (see FIG. 3), and has a stickiness because the transport surface side of the surface is made of silicon rubber. The sheet conveyed by the pair of sheet feeding rollers 5a and 5b is held in the clockwise direction (in the direction of the arrow 50) of one roller 6 while being held on the conveying surface of the conveying belt 8 by the adhesion force. The sheet is conveyed toward the downstream side in the conveyance direction (right side in the figure) by rotational driving.

  Holding members 9a and 9b are disposed at the insertion and discharge positions of the sheet with respect to the roller 6, respectively. The holding members 9a and 9b are for pressing the paper against the transport surface of the transport belt 8 so that the paper on the transport belt 8 is not lifted from the transport surface and transporting the paper onto the transport surface.

  A peeling mechanism 10 is provided on the downstream side (right side in the drawing) of the conveyance belt 8 along the sheet conveyance path. The peeling mechanism 10 is configured to peel the sheet held by the adhesion force on the conveyance surface of the conveyance belt 8 from the conveyance surface and send it to the right paper discharge unit 12 side.

  Each of the four inkjet heads 2 has a head body 2a at the lower end. The head main bodies 2a each have a rectangular cross section, and are arranged close to each other so that the longitudinal direction thereof is a direction perpendicular to the paper transport direction (the direction perpendicular to the paper surface in FIG. 1). That is, the printer 1 is a line type printer. A large number of nozzles are provided on the bottom surfaces of the four head bodies 2a, and magenta, yellow, cyan, and black inks are ejected from each of the four head bodies 2a.

  The head main body 2a is disposed so that a small amount of gap is formed between the lower surface of the head main body 2a and the conveyance surface of the conveyance belt 8, and a sheet conveyance path is formed in the gap portion. Therefore, when the paper transported by the transport belt 8 sequentially passes immediately below the four head main bodies 2a, each color ink is ejected from the nozzle toward the upper surface (printing surface) of the paper, thereby Thus, a desired color image can be formed.

  A reflective photosensor 40 for detecting the position of the conveyor belt 8 (more specifically, the position of a later-described recess 24) is disposed in the vicinity of the roller 6 in the lower path of the conveyor belt 8. The photosensor 40 is disposed away from the surface of the conveyor belt 8 and includes a light emitting unit and a light receiving unit.

  In a region surrounded by the conveyor belt 8, a substantially rectangular parallelepiped shape (supporting the conveyor belt 8 and the conveyor belt 8) is supported from the inner peripheral side by contacting the lower surface of the conveyor belt 8 at a position facing the inkjet head 2, that is, the upper side. A guide member 21 having the same width is disposed.

  In the vicinity of the roller 6 in the upper path of the conveyor belt 8 and on both sides of the width of the conveyor belt 8, substantially rectangular parallelepiped-shaped ink holding members 27a and 27b made of felt or the like (only 27a is depicted by a one-dot chain line in FIG. 1). Is arranged. The ink holding members 27a and 27b can selectively take either a position in contact with the conveying belt 8 or a position in non-contact with a driving mechanism (see FIGS. 5 and 6) such as a motor 30 described in detail later. It is possible (see FIG. 2).

  The guide member 21, the ink holding members 27a and 27b, the transport belt 8, and the like constitute the belt transport mechanism 13 of the present embodiment.

  The conveyor belt 8 has a two-layer structure in which two sheet-like members are bonded together. As described above, the inner sheet-like member 8a is made of a polyester base material impregnated with urethane, and the outer sheet-like member 8b is made of silicon rubber (see FIG. 3). Since a part of the inner sheet-like member 8a is not covered with the outer sheet-like member 8b, only one recess 24 having the same height as the thickness of the outer sheet-like member 8b is provided on the surface of the conveying belt 8. It has been.

  In the inkjet printer 1, the sheet conveyance timing is adjusted so that the sheet is conveyed by a portion other than the recess 24.

  As shown in FIGS. 2 to 4, the recess 24 has a width substantially equal to the belt width in plan view, and the stepped portion 24 a on the upstream side in the running direction is a top portion 24 b on the downstream side in the running direction at the center position in the belt width direction. It is V-shape which exhibits. That is, in the stepped portion 24a, both width ends of the conveyor belt 8 are located on the upstream side in the running direction from the width center. The step portion 24c on the downstream side in the running direction has a linear shape along the belt width direction.

  As shown in FIGS. 3 and 4, the stepped portion 24a has an overhang shape in which the lower half of the stepped portion 24a is in contact with the inner sheet-like member 8a to form a groove 24d, so that the upper end faces the downstream side in the running direction. is doing.

  A water-repellent sheet 25 having a water-repellent finish applied to the bottom surface of the concave portion 24 by being coated with a silicon agent or the like is disposed on the bottom surface of the concave portion 24 and hardly absorbs ink.

  In the recess 24, the distance L1 (see FIG. 2) between the top 24b and the step 24c is slightly longer than the two widths of the head body 2a. This is because, as will be described later, the flushing to the recess 24 is set to be performed in units of two inkjet heads 2.

  The position of the recess 24 can be detected by the above-described photosensor 40 (see FIG. 1). The light emitting unit in the photosensor 40 constantly emits light toward the surface of the conveyance belt 8, and the light reflected by the surface of the conveyance belt 8 is received by the light receiving unit. Whether or not the concave portion 24 is at the installation position of the photosensor 40 is detected from the intensity of the reflected light detected by the light receiving portion. Based on this, the traveling speed of the conveyor belt 8, and the distance from the photosensor 40, the position of the recess 24 at an arbitrary time can be known.

  Here, the drive mechanism of the ink holding members 27a and 27b will be described. FIG. 5 is a partial plan view showing a drive mechanism of the ink holding member shown in FIG. FIG. 5 is a view as seen from the front side of the conveyor belt 8 in the vicinity of the ink holding members 27a and 27b, and the conveyor belt 8 is indicated by a two-dot chain line. 6 is a cross-sectional view taken along line VI-VI in FIG.

  As shown in FIGS. 5 and 6, the ink holding members 27a and 27b are accommodated in holders 27x and 27y made of resin or the like, respectively. The holders 27x and 27y are biased by springs 40a and 40b in a direction away from the belt in the width direction of the transport belt 8. One end of each holder 27x, 27y is connected to racks 38a, 38b arranged along the width direction of the conveyor belt 8 on the back side of the conveyor belt 8. The racks 38 a and 38 b mesh with each other at the width center portion of the transport belt 8 via the pinion 39.

  A connection portion between the holder 27x of the ink holding member 27a and the rack 38a extends outward in the width direction of the transport belt 8, and is connected to a cam portion 33 supported by the main body frame via a roller 35. The roller 35 meshes with the eccentric cam 32 in the cam portion 33. A cam gear 31 that is coaxial and interlocked is disposed below the eccentric cam 32, and the cam gear 31 meshes with the motor gear 30 a of the motor 30.

  In such a configuration, when the motor 30 rotates forward or backward, this rotation is transmitted to the motor gear 30a, the cam gear 31, and the eccentric cam 32. Since the eccentric cam 32 is eccentric from the central axis, it moves together with the roller 35 in the direction of approaching or moving away from the conveyor belt 8 along the width direction of the conveyor belt 8. As a result, the holder 27x and the ink holding member 27a connected to the roller 35 move in a direction toward or away from the transport belt 8. The ink holding member 27b disposed opposite to the ink holding member 27a moves simultaneously with the ink holding member 27a and in the opposite direction since the holder 27y is connected to the rack 38a via the pinion 39. That is, the ink holding members 27 a and 27 b operate simultaneously in the direction approaching or separating from the conveyance belt 8 along the width direction of the conveyance belt 8 by driving the motor 30.

  While the motor 30 is not driven, the ink holding members 27a and 27b, the holders 27x and 27y, etc. are both separated from the transport belt 8 by the bias of the springs 40a and 40b. Further, when the ink holding members 27 a and 27 b move in the direction approaching the conveyance belt 8 along the width direction of the conveyance belt 8, the ink holding members 27 a and 27 b come into contact with the width end portion of the conveyance belt 8, so Stops at a position separated by a distance.

  Such an operation of the ink holding members 27a and 27b is performed according to the position of the recess 24 that changes as the transport belt 8 travels. That is, when the recess 24 is in a position corresponding to the ink holding members 27a and 27b, the ink holding members 27a and 27b are in contact with the transport belt 8, and when the recess 24 is in a position not corresponding to the ink holding members 27a and 27b. The members 27a and 27b are separated from the conveyor belt 8. This is based on the position of the recess 24 detected by the photosensor 40 (see FIG. 1), the traveling speed of the conveyor belt 8, and the traveling distance of the conveyor belt 8 from the photosensor 40 to the ink holding members 27a and 27b. This is realized by driving the motor 30 at a predetermined time.

  Next, the movement of the ink flushed on the conveying belt 8 will be described with reference to FIGS. FIGS. 7A to 7D are enlarged cross-sectional views of the vicinity of the concave portion at the center position in the belt width direction of the conveying belt, shown in order of the passage of time along with the traveling of the conveying belt. Each of the cases in the upper path is drawn.

  In order to perform the flushing, first, as shown in FIG. 7 (a), the two head main bodies 2a close to the roller 7 out of the four head main bodies 2a have a region between the top 24b and the stepped portion 24c in the recess 24. The conveyor belt 8 is caused to travel to the facing position. Then, after the traveling of the transport belt 8 is stopped, ink is ejected from all the nozzles of the two head bodies 2a toward the concave portion 24 of the transport belt 8 (flushing). Then, the ejected ink 3 is disposed on the inner sheet-like member 8a (more specifically, on the water-repellent sheet 25) which is the bottom surface of the recess 24.

  Thereafter, the conveyor belt 8 is caused to travel so that the region between the top 24b and the stepped portion 24c in the recess 24 faces two head main bodies 2a near the roller 6 among the four head main bodies 2a. Then, after the traveling of the transport belt 8 is stopped, ink is ejected from all the nozzles of the two head main bodies 2 a toward the concave portion 24 of the transport belt 8. Then, the ejected ink 3 is disposed on the inner sheet-like member 8a (more specifically, on the water-repellent sheet 25) which is the bottom surface of the recess 24.

  When the conveyor belt 8 is run in this state, the ink 3 moves in the recess 24 in the direction opposite to the running direction, that is, upstream in the running direction due to inertia, and reaches the stepped portion 24a as shown in FIG. 7B. After that, the groove 24d moves along the width of the conveyor belt 8 to both ends. Then, as shown in FIG. 7C, the ink 3 hardly exists in the recess 24.

  When the conveyor belt 8 further travels and the portions corresponding to both width ends of the conveyor belt 8 of the groove 24d come into contact with the ink holding members 27a and 27b as shown in FIG. 7D, the conveyor belt 8 is at this timing. Is temporarily stopped. At this time, the ink 3 in 24d is absorbed and held by the ink holding members 27a and 27b by the capillary force generated by the ink holding portion 27a27b, and is discharged from the inside of the groove 24d.

  Note that the traveling speed of the transport belt 8 and the positions and sizes of the ink holding members 27a and 27b are such that when the ink 3 moving in the groove 24d first reaches both width ends of the transport belt 8, that portion is the ink holding member. It is set so that it is already in contact with 27a, 27b.

  In addition, when the ink holding members 27a and 27b hold the ink 3, even if the conveying belt 8 continues to run without being stopped, the running speed of the conveying belt 8 and the positions and sizes of the ink holding members 27a and 27b are adjusted as appropriate. By doing so, it is possible to discharge all the ink 3 in the groove 24d from the inside.

  As described above, the inkjet printer 1 using the belt conveyance mechanism 13 of the present embodiment is a line type, but ejects ink toward the recess 24 without having to retract the conveyance belt 8 or the inkjet head 2. Thus, quick flushing is possible with a relatively simple configuration. Therefore, the manufacturing cost can be reduced, and the ink jet printer 1 can be reduced in size and the number of printed sheets per unit time can be improved.

  Further, since the opening for flushing is not formed in the transport belt 8 and only the recess 24 is provided, the strength of the transport belt 8 is hardly reduced. Therefore, a desired belt tension can be obtained, there is no trouble in the paper conveyance process, and the life of the conveyance belt 8 is hardly reduced.

  Further, the ink 3 flushed in the concave portion 24 moves along the groove 24d provided in the direction opposite to the traveling direction in the concave portion 24 due to inertia to move to both ends of the width of the conveying belt 8 along the groove 24d. By being quickly absorbed by the ink holding members 27 a and 27 b arranged at both width ends of the belt 8, the belt 8 is quickly removed from the surface of the conveyance belt 8. For this reason, there is almost no trouble in printing after flushing.

  Further, since the bottom surface of the recess 24 has water repellency, the flushed ink 3 smoothly moves in the recess 24 in the direction opposite to the traveling direction as the transport belt 8 travels. Therefore, the ink 3 can be efficiently held by the ink holding members 27a and 27b.

  Further, a position where the ink holding members 27a and 27b are in contact with the conveying belt 8 and a position where they are not in contact can be selectively taken by a driving mechanism such as the motor 30 shown in FIGS. More specifically, the ink holding members 27a and 27b are driven by the motor 30 or the like based on the position of the concave portion 24 detected by the photosensor 40 and the traveling speed of the conveyor belt 8, and the concave portion 24 is moved to the ink holding member 27. The ink holding members 27a and 27b come into contact with the transport belt 8 when in the corresponding positions, and the ink holding members 27a and 27b are separated from the transport belt 8 when the recess 24 is in a position not corresponding to the ink holding member 27. ing. This makes it possible to minimize friction between the ink holding members 27a and 27b and the transport belt 8. Further, since it is possible to minimize the ink that has soaked into the ink holding members 27a and 27b from adhering to the conveying belt 8, this also has the advantage that the occurrence of belt slip and the transfer of ink onto the paper can be suppressed. .

  Further, the ink 3 ejected into the recess 24 of the transport belt 8 does not adhere to places other than the ink holding members 27 a and 27 b such as the back surface of the transport belt 8 and the rollers 6 and 7. Therefore, the occurrence of belt slippage due to the ink 3 and the ink transfer onto the paper can be minimized.

  Further, since the stepped portion 24a has an overhang shape whose upper end faces the downstream side in the running direction, the energy of the ink 3 directed toward the stepped portion 24a can be diffused in the groove 24d and is flushed. Ink 3 is less likely to overflow from the recess 24 beyond the step 24a.

  Further, since the stepped portion 24 a has a V shape with a top portion 24 b on the downstream side in the traveling direction, the ink 3 moves to both ends of the width of the conveying belt 8 as the conveying belt 8 travels. According to this, compared with the case where the ink 3 is guided only to one width end portion of the conveyor belt 8, the ink passing amount at each width end portion is halved, so that the flushed ink 3 overflows from the recess 24. Less. Further, as compared with the case where the ink 3 is guided only to one width end portion of the conveyance belt 8, when the distance L1 is kept constant, the portion corresponding to the width ends of the conveyance belt 8 of the groove 24d and the step portion 24c. Can be shortened. That is, since the overall length of the recess 24 can be formed relatively short, the sheet conveyance timing control is facilitated.

  Here, with reference to FIG.8 and FIG.9, the modification of the recessed part formed in the conveyance belt 8 is demonstrated. FIG. 8 is a partial plan view showing a modified example of the conveyance belt depicted in FIG. FIG. 9 is a partial cross-sectional view of the transport belt shown in FIG. 8 and 9 show a case where the recess 34 is in the upper path of the transport belt 8.

  In this modification, the recess 34 is a trapezoid having a width equal to the belt width in plan view. The stepped portion 34a on the upstream side in the running direction has a linear shape inclined about 20 ° with respect to the belt width direction, and the stepped portion 34c on the downstream side in the running direction has a linear shape along the belt width direction. As shown in FIGS. 8 and 9, the cross section of the stepped portion 34 a is inclined so as to form an angle of about 45 ° from the inner upper side of the concave portion 34 toward the lower outer side. That is, the stepped portion 34a has an overhang shape in which the upper end protrudes downstream in the traveling direction, and the space below the stepped portion 34a is a groove 34d.

  According to this modification, since the stepped portion 34a has a shape as shown in FIG. 8, ink is guided only to one width end portion of the stepped portion 34a as the conveyor belt 8 travels. Therefore, the ink holding member 37 may be disposed only on one side of the conveying belt 8 (the side corresponding to the width end portion on the upstream side in the running direction of the stepped portion 34a), and the device configuration including the drive mechanism of the ink holding member 37 is included. Is simplified. However, in this case, the amount of ink guided to one width end of the stepped portion 34a is about twice that in the case of FIG.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims.

  For example, the shape of the stepped portions 24a and 34a on the upstream side in the running direction in the recesses 24 and 34 is not limited to the V shape or the linear shape as long as the ink can be guided to at least one of the width end portions.

  Further, the step portions 24a and 34a do not necessarily have an overhang shape that faces the downstream side in the traveling direction. Even when the stepped portions 24a and 34a have an overhang shape, the shape is not limited to that illustrated in the drawings, and can be changed to any shape.

  Further, the distance between the end portions on the downstream side in the running direction of the step portions 24a and 34a in the concave portions 24 and 34 and the step portions 24c and 34c (for example, L1 and L2 shown in FIGS. 2 and 8) can be changed, and the head body 2a. The distance may be slightly longer than one width or four widths. At this time, the unit of the head main body 2a for performing flushing may be changed.

  Moreover, you may use things other than polyester as a material of an inner side sheet-like member. The ink holding members 27a, 27b, and 37 are not limited to being made of felt.

  Moreover, the conveyance belt 8 does not necessarily have a two-layer structure, and may have a layer structure of, for example, three or more layers or only one layer.

  Furthermore, although the ink holding members 27a, 27b, and 37 are movable, they may be fixed so as to be always in contact with the width end portion of the transport belt 8, for example.

  Further, the sizes and installation positions of the ink holding members 27a, 27b, and 37 can be arbitrarily changed within a range in which the ink 3 can be sufficiently absorbed.

  The belt transport mechanism 13 may further include a mechanism for discharging the ink absorbed by the ink holding members 27a, 27b, and 37 to the outside.

  The present invention is applicable not only to a line type but also to a serial type ink jet printer.

  Furthermore, the present invention is not limited to an ink jet printer, and can be applied to, for example, an ink jet facsimile and a copying machine.

It is a front view showing an ink jet printer (ink jet recording device) provided with a belt conveyance mechanism concerning one embodiment of the present invention. FIG. 2 is a partial plan view of the conveyance belt depicted in FIG. 1. FIG. 3 is a partial cross-sectional view of the conveyance belt shown in FIG. 2. FIG. 3 is a partial perspective view of the conveyance belt shown in FIG. 2. FIG. 3 is a partial plan view showing a drive mechanism for the ink holding member shown in FIG. 2. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG. 6 is an enlarged cross-sectional view of the vicinity of a concave portion at the center position in the belt width direction of the transport belt, shown in order of time as the transport belt runs. FIG. 6 is a partial plan view showing a modification of the conveyance belt depicted in FIG. 1. It is a fragmentary sectional view of the conveyance belt shown in FIG.

Explanation of symbols

1 Inkjet printer (inkjet recording device)
2 Inkjet head 6, 7 Roller 8 Conveying belt 13 Belt conveying mechanism 24, 34 Recessed parts 24a, 34a Stepped parts 27a, 27b, 37 Ink holding member 30 Motor (drive mechanism)
40 sensors

Claims (8)

Multiple rollers,
A conveying belt for conveying a recording medium spanned by the plurality of rollers;
A recess formed on the surface of the transport belt so that ink moves to at least one of the width end portions of the transport belt as the transport belt travels;
An ink holding member disposed at the width end for holding the ink moved in the recess ,
The step portion on the upstream side in the running direction of the conveyor belt in the concave portion is characterized in that at least one of the width end portions of the conveyor belt is located on the upstream side in the running direction from the center of the width. Transport mechanism.   The belt conveyance mechanism for an ink jet recording apparatus according to claim 1, wherein a bottom surface of the recess has water repellency.   3. The belt conveyance mechanism for an ink jet recording apparatus according to claim 1, wherein the concave portion is formed so that ink moves to both width ends of the conveyance belt as the conveyance belt runs. . The step portion is an ink jet recording apparatus belt conveying mechanism according to any one of claims 1 to 3, characterized in that the width ends of the conveyor belt is positioned in the traveling direction upstream side of the width center . The stepped portion in the running direction upstream side of the conveyor belt in the recess, any one of claims 1 to 4, characterized in that the upper end has an overhang shape facing the direction of travel downstream A belt conveyance mechanism for an ink jet recording apparatus according to the item 1. It said ink holding member is an ink jet recording apparatus belt conveying mechanism according to any one of claims 1 to 5, characterized in that a position not in contact with the position in contact with the conveyor belt can take selectively. Multiple rollers,
A conveying belt for conveying a recording medium spanned by the plurality of rollers;
A recess formed on the surface of the transport belt so that ink moves to at least one of the width end portions of the transport belt as the transport belt travels;
An ink holding member disposed at the width end for holding the ink moved in the recess;
A sensor for detecting the position of the recess formed in the conveyor belt;
A drive mechanism for operating the ink holding member in contact with or not in contact with the transport belt based on the position of the recess detected by the sensor and the traveling speed of the transport belt;
A belt transport mechanism for an ink jet recording apparatus, comprising: The belt conveyance mechanism according to any one of claims 1 to 7 ,
An inkjet head that ejects ink onto a recording medium conveyed by the conveyance belt in the belt conveyance mechanism;
An ink jet recording apparatus comprising:

Images