JP2010089289A - Transport mechanism for printing apparatus - Google Patents

Abstract

In an ink jet printing apparatus, an ink mist generated when ink is ejected causes a conveyor belt to slip with respect to a belt driving roller and to prevent contamination of printed matter.
A transport mechanism of a printing apparatus for forming an image on a recording medium by ejecting ink from an ink head to a recording medium transported on the transport path, the transport path facing the ink head. A platen belt 160 that moves on the surface is arranged. The platen belt 160 has a number of belt holes 165 that penetrate through the front and back surfaces thereof, and the belt hole 165 has an expanded portion 166 that is partially expanded. Is formed.
[Selection] Figure 6

Description

  The present invention relates to a transport mechanism of a printing apparatus that forms an image on a recording medium by ejecting ink from an ink head onto a recording medium transported on a transport path.

  Conventionally, as an inkjet method, there is a full line type in which recording is performed only by sub-scanning in which a recording medium is transported in the transport direction. With this full line type, recording for one line is continuously performed on the recording medium in a batch. .

  By the way, in recent printing apparatuses, there are high demands such as elaboration of printed images, multifunctional functions of the apparatus, miniaturization, etc., and it is necessary to install ink heads having a complicated configuration of high-density pixels close to each other. As shown in FIG. 11, when a droplet (mist) other than the main droplet 115 discharged from the ink head 110a is generated, the mist has a relatively small mass and speed. However, a large number of the platen belt 160 may be perforated and sucked from the belt hole 165 for attracting the recording medium, or may float and directly adhere to another head or head holder. As a result, the ejection failure of the ink head due to the ejection port of the ink head being blocked, ejection failure such as insufficient ejection amount, etc. The printed matter sometimes fell on the belt and became dirty.

  As a technology that meets these requirements, there has been proposed a printing apparatus that is provided with a mist collecting unit that provides holes in the conveying belt and sucks and collects floating mist in the printing apparatus by a suction fan (Patent Document 1).

However, there is a problem that the back surface of the recording medium is soiled when ink mist adheres to the surface of the conveyor belt simply by providing a hole in the conveyor belt as in the means disclosed in Patent Document 1. In addition, when the ink mist that has entered the hole oozes out on the back surface of the transport belt, the transport belt and the belt driving roller that drives the belt become slippery, and the printing position determination of the recording medium is unstable. Thus, the precision of the printed image is lowered.
JP 2004-262147 A

  Accordingly, the present invention has been made in view of the above points, and printing that can prevent the conveyance belt from slipping with respect to the belt driving roller or contamination of the printed matter due to ink mist generated during ink ejection. It is an object of the present invention to provide a transport mechanism for the apparatus.

  In order to solve the above problems, the present invention provides a transport mechanism for a printing apparatus that forms an image on a recording medium by ejecting ink from the ink head onto a recording medium transported on a transport path. A conveyor belt that moves on the surface of the conveyance path opposite to the belt is disposed, and the conveyor belt has a number of belt holes penetrating the front and back of the conveyor belt. Is formed.

  According to the present invention, the mist floating in the printing apparatus passes through the belt hole and is discharged to the lower surface of the conveyance belt. At this time, since the widened portion provided in the belt hole is a concave portion that does not come into contact with the belt driving roller or the recording medium, the floating mist is attached to and held by the widened portion when passing through the belt hole. Therefore, it is possible to prevent the mist from adhering to the surface of the belt driving roller and the conveying belt.

  In the above invention, it is preferable that the widened portion is a concave portion that is widened on the back surface side of the conveyor belt. In this case, since the concave portion on the back surface side of the transport belt does not come into contact with the belt driving roller, the ink mist attached and held in the concave portion does not contaminate the belt driving roller.

  In the said invention, it is preferable that an expansion part is a recessed part expanded on the surface side of the conveyance belt. In this case, since the concave portion on the surface side of the conveying belt does not come into contact with the recording medium, the ink mist attached and held in the concave portion does not contaminate the belt driving roller.

  In the above invention, it is preferable that the expanding portion is a space expanded in the conveyor belt in the middle of the belt hole. In this case, since the concave portion in the middle of the conveyance belt does not come into contact with the belt driving roller and the recording medium, the ink mist attached and held in the concave portion does not contaminate the belt driving roller and the recording medium.

  In the said invention, it is preferable that the expansion part is connected with the other adjacent expansion part. In this case, it is possible to maximize the volume of the expanded portion in the transport belt, and it is possible to attach and hold more ink mist. Moreover, the manufacturing process of the expansion part in a conveyance belt can also be reduced, and manufacturing cost can be reduced. At this time, the communication with the other expanded portions may be in either the main direction or the sub direction, or may be a lattice shape in which both are formed.

  As described above, according to the present invention, in an ink jet printing apparatus, ink mist generated when ink is ejected causes the conveyor belt to slip with respect to the belt driving roller, and to prevent contamination of printed matter. Can do.

(Overall configuration of printing device)
Embodiments of the present invention will be described with reference to the drawings. FIG. 1A is a configuration diagram illustrating an outline of a recording medium conveyance path of the printing apparatus 100 according to the present embodiment. In this embodiment, the printing apparatus 100 includes a plurality of ink heads on which a large number of nozzles are formed, discharges black or color ink from each ink head, performs printing in line units, and prints on a recording medium on a conveyance belt. An ink-jet line color printer that forms a plurality of images so as to overlap each other will be described as an example.

  As shown in FIG. 1A, the printing apparatus 100 is an apparatus that forms an image on the surface of a recording medium that is conveyed on an annular conveyance path, and the conveyance path is a paper feed conveyance path that supplies the recording medium This is generally composed of an FR, a normal path CR from the paper feed system conveyance path FR through the head unit 110 to the paper discharge path DR, and a reverse path SR branched and connected to the normal path CR.

  In the paper feed system conveyance path FR, as a paper feed mechanism for supplying the recording medium, a side paper feed stand 120 disposed outside the side surface of the housing and a plurality of paper feed trays (inside the housing) 130a, 130b, 130c, 130d). In addition, a paper discharge port 140 is provided as a paper discharge mechanism for discharging the printed recording medium.

  The recording medium fed from one of the side paper feed tray 120 and the paper feed tray 130 is transported along a paper feed system transport path FR in the housing by a driving mechanism such as a roller, and the recording medium It is guided to the resist portion R which is the reference position of the head portion. A head unit 110 having a plurality of print heads is provided further on the registration direction R in the transport direction side. While the recording medium is conveyed at a speed determined by printing conditions by a platen belt 160 that is a conveying belt provided on the opposite surface of the head unit 110, an image is formed line by line with ink ejected from each print head.

  The printed recording medium is further conveyed on the normal route CR by a driving mechanism such as a roller. In the case of single-sided printing in which printing is performed only on one side of the recording medium, the paper is directly discharged to the paper discharge port 140 through the paper discharge path DR, and is discharged as a tray for the paper discharge port 140. It is loaded on the table 150 with the printing surface facing down. The paper discharge table 150 has a tray shape protruding from the housing, and has a certain thickness. The sheet discharge table 150 is inclined, and the recording medium discharged from the sheet discharge port 140 is naturally arranged and overlapped by a wall formed at a position below the inclination.

  On the other hand, in the case of double-sided printing in which printing is performed on both sides of the recording medium, the front side (the first printed side is “front side” and the next printed side is “back side”). Without being guided to, the inside of the casing is further transported and sent out to the reverse path SR. For this reason, the printing apparatus 100 is provided with a switching mechanism 170 for switching the transport path for backside printing, and the recording medium that has not been sent to the discharge path by the switching mechanism 170 is drawn into the reversing path SR.

  In the reverse path SR, the recording medium is delivered from the normal path CR, and so-called switchback is performed in which the recording medium is reversed by reciprocating the recording medium. Then, it is returned to the normal route CR via the switching mechanism 172 by a driving mechanism such as a roller, is fed again through the registration portion R, and the back side is printed by the same procedure as the front side. Thereafter, the recording medium on which the back side is printed and images are formed on both sides is guided to the paper discharge port 140 through the paper discharge route DR and discharged, and the paper discharge is provided as a receiving base of the paper discharge port 140. It is loaded on the table 150.

  In the present embodiment, switchback at the time of duplex printing is performed using a space provided in the paper discharge tray 150. The space provided in the paper discharge tray 150 is configured to be covered so that the recording medium cannot be removed from the outside during switchback. As a result, it is possible to prevent the user from accidentally pulling out the recording medium during the reversing operation. Further, the paper discharge tray 150 is originally provided in the printing apparatus 100, and by performing switchback using the space in the paper discharge tray 150, a separate switchback is provided in the printing apparatus 100. There is no need to provide space. Therefore, an increase in the size of the housing can be prevented. Furthermore, since the paper discharge path and the reverse path are not shared, the switchback process and the discharge of other recording media can be performed in parallel.

  In the printing apparatus 100, the recording medium that has been printed on one side is also fed again to the registration portion R that is the reference position of the leading portion of the fed recording medium. For this reason, a junction point where the conveyance path of the newly fed recording medium and the refeed path where the recording medium for backside printing is circulated is merged is formed immediately before the registration portion R. Is done. Then, the registration unit R sends out the recording medium in the vicinity of the merging point between the paper feeding system conveyance path FR and the normal path CR.

  In the present embodiment, the path on the sheet feeding mechanism side is defined as the sheet feeding system conveyance path FR, and the other path is defined as the conveyance path with reference to the merging point. This transport path is annular, and includes the normal path CR and the reverse path SR as described above. FIG. 1B is an explanatory diagram schematically showing the sheet feeding system conveyance path FR, the normal path CR, and the reverse path SR. In the figure, the number of rollers constituting the drive unit is omitted as appropriate.

  In the paper feed system conveyance path FR, the side paper feed driving unit 220 for feeding paper from the side paper feed tray 120 and the paper feed from the paper feed trays 130 (130a, 130b, 130c, 130d) are provided. A tray 1 driving unit 230a, a tray 2 driving unit 230b,. Thus, a sheet feeding unit for feeding the recording medium to the registration unit R is configured.

  Further, any of the driving units (tray 1 driving unit 230a, tray 2 driving unit 230b...) In the above-described paper feeding system conveyance path FR includes a driving mechanism composed of a plurality of rollers or the like. Are taken one by one and conveyed in the direction of the registration portion R. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with a paper feed mechanism that feeds paper.

  In addition, a plurality of conveyance sensors are arranged in the paper feeding system conveyance path FR so that a conveyance jam in the paper feeding system conveyance path FR can be detected. That is, each conveyance sensor is a sensor that detects the presence or absence of a recording medium or the leading edge of the recording medium. For example, a plurality of conveyance sensors are arranged at appropriate intervals on a conveyance path, and a conveyance sensor provided on the paper feeding side is provided. If the conveyance sensor on the conveyance direction side does not detect the recording medium within a predetermined time after detecting the recording medium, it can be determined that a conveyance jam has occurred.

  Among these conveyance sensors, a registration sensor in front of the registration unit R that sends out the recording medium measures the size of the recording medium that is being conveyed, for example, based on the passing speed and the passing time of the recording medium, A transport jam (paper feed error) occurs when the transport sensor does not detect the recording medium within a predetermined time after measuring the size of the medium or driving the side paper feed drive unit 220, the tray 1 drive unit 230a, etc. Can be determined.

  The normal path CR forms a part of the circulation transport path, and is a path from the paper feed transport path FR that supplies the recording medium to the paper discharge path DR through the head unit 110, and the recording is performed on the normal path CR. An image is formed on the top surface of the medium. The normal path CR includes a registration driving unit 240 that guides the recording medium to the registration unit R, a belt driving unit 250 that drives the platen belt 160 provided on the facing surface of the head unit 110 to move endlessly, and a conveyance direction side. The first upper surface transport driving unit 260 and the second upper surface transport driving unit 265, which are sequentially arranged, the upper surface discharge driving unit 270 that guides the printed recording medium to the paper discharge port 140, and the recording medium is pulled into the reverse path SR for back surface printing. Driving means are provided. Each drive unit includes a drive mechanism composed of one or a plurality of rollers or the like, and conveys the recording medium one by one along the conveyance path. Each drive unit can be driven independently, and necessary drive unit operations are performed in accordance with the conveyance status of the recording medium.

  Further, a plurality of conveyance sensors are also arranged on the normal route CR so that a conveyance jam in the normal route CR can be detected. Further, it is possible to confirm that the recording medium is appropriately conveyed also in the resist portion R. In the normal route CR, a conveyance sensor is provided corresponding to the drive unit, and it is possible to specify in which drive unit of the normal route CR the conveyance jam has occurred.

  The reversing path SR is branched and connected to the normal path CR, the recording medium is transferred from the normal path CR, and the recording medium is reciprocated (switched back) to return to the normal path CR to reverse the front and back of the recording medium. The reversing path SR is provided with a reversing drive unit 281 that reverses the recording medium and guides it to the joining point. The reversing path SR can be transported at a speed different from that of the normal path CR, and when taking over the recording medium from the normal path CR, it is accelerated or decelerated, and the stop time at the time of switchback is extended or shortened. Can be.

  In the present embodiment, after a certain recording medium is fed, the next recording medium is not fed after waiting for the recording medium to be printed and discharged. Before the recording medium is discharged, the succeeding recording medium can be fed and printed continuously at a predetermined interval. Therefore, in normal scheduling at the time of duplex printing, a space is secured in advance so as to secure a position where the recording medium returned from the reversing path SR is inserted when feeding the recording medium on the front surface. Thereby, in this apparatus, printing on the front surface and printing on the back surface can be performed in parallel, and half the productivity can be ensured with respect to single-sided printing.

  The platen belt 160 is wound around a driving roller 161 and a driven roller 162 disposed at the front end and the rear end of the surface facing the head unit 110, and rotates in a clockwise direction in FIG. Also, on the upper surface of the platen belt 160, four color ink heads are arranged side by side along the belt moving direction, and a head unit 110 that forms a color image so that a plurality of images overlap each other is disposed oppositely. Yes.

  Further, as illustrated in FIG. 1, the printing apparatus 100 includes an arithmetic processing unit 330. The arithmetic processing unit 330 is configured by a processor such as a CPU or DSP (Digital Signal Processor), memory, hardware such as other electronic circuits, software such as a program having the function, or a combination thereof. Various functional modules are virtually constructed by appropriately reading and executing a program, and various functional modules for processing related to image data, operation control of each unit, and user operations are constructed by each constructed functional module. Process. In addition, an operation panel 340 is connected to the arithmetic processing unit 330, and an instruction and a setting operation by a user can be received through the operation panel 340.

(Conveying mechanism in the image forming path)
FIG. 2 is an explanatory view showing an image forming path on which image formation is performed from the side, and FIG. 3A is an explanatory view showing a head holder 500 arranged above the image forming path from below. FIG. 3B is an explanatory diagram showing an enlarged side cross-section of the head holder 500. FIG. 4 is a perspective view showing the head holder 500 from above.

  More specifically, the normal path CR of the recording medium includes an image forming path CR1 composed of a platen belt 160, a driving roller 161, a driven roller 162, and the like. A holder 500 is provided. The head holder 500 is a box having a head holder surface 500a on the bottom surface, and holds and fixes the ink head 110a, and stores other functional parts for discharging ink from the ink head 110a as a unit. .

  Further, the head holder surface 500a that is the bottom surface of the head holder 500 is disposed so as to be parallel to the transport path. A plurality of mounting openings 500b having the same shape as the horizontal cross section of each of the plurality of ink heads 110a constituting the head unit 110 are arranged on the head holder surface 500a, and the plurality of ink heads 110a are respectively inserted into the mounting openings 500b. Thus, the discharge port is projected from the head holder surface 500a.

  The ink heads 110a are arranged over a plurality of columns in a direction (main scanning direction) orthogonal to the transport direction (sub-scanning direction), and within these columns, the ink heads included in each column are located in other adjacent columns. The ink heads included are arranged in a staggered manner so that a portion that does not overlap in the transport direction is generated. Each row of these ink heads is arranged at a predetermined interval in the transport direction, a main direction flow path 111 is formed between the rows, and each adjacent ink head in the same row is arranged at a predetermined interval. A sub-direction flow path 112 is formed between the ink heads. The main-direction flow path 111 and the sub-direction flow path 112 communicate with each other to form a mesh-like mist discharge path. As shown in FIG. 3B, in the present embodiment, the protruding length H of the ink head 110a from the head holder surface 500a is larger than the width L of the main flow path.

  Each main direction channel 111 is provided with a stepped guide roller 510. The stepped guide roller 510 is formed by connecting guide rollers having different diameters as a single roller, and is formed by cutting a metal rod, for example. Specifically, the stepped guide roller 510 includes an upstream guide roller 510a having a large diameter and a downstream guide roller 510b having a diameter smaller than that of the upstream guide roller 510a alternately connected on the same rotation axis. The arrangement is arranged. The upstream guide roller 510a is provided on the upstream side of each ink head 110a in the transport direction, is biased downward, is pressed against the upper surface of the transport path, and rotates. On the other hand, the downstream guide roller 510b is provided on the downstream side of each ink head 110a in the transport direction, and is rotatably supported at a predetermined distance from the upper surface of the transport path.

  In correspondence with the staggered arrangement of the ink heads, the upstream guide roller 510a and the downstream guide roller 510b are also staggered. In addition, since the stepped guide roller 510 is disposed in the main direction flow path 111, the upstream guide roller 510a and the downstream guide roller 510b are also alternately disposed in the main direction flow path 111. Become. In the present embodiment, the stepped guide roller 510 is rotatably supported by bearings 520 disposed on both sides of the head holder surface 500 a and has an integrated structure with the head holder 500.

  Next, the recording medium transport mechanism in the image forming path CR1 will be described. FIG. 5 is a top view showing the recording medium transport mechanism of the image forming path CR1 according to the present embodiment with a part cut away. As shown in FIG. 5, the image forming path CR <b> 1 includes a platen belt 160, a driving roller 161, a driven roller 162, and a plastic template 620.

  The platen belt 160 is an endless belt member that has a number of belt holes 165 for attracting the recording medium and slides in a range facing the ink head 110a in the conveyance path to convey the recording medium. Specifically, the platen belt 160 is wound around a pair of driving rollers 161 and driven rollers 162 arranged orthogonal to the transport direction, and circulates in the transport direction.

  The pla template 620 is a plate-like member that supports the platen belt 160 so as to be slidable at a position facing the ink head 110a, and has a large number of suction holes 622 that pass through the belt holes 165. A suction fan is provided below the plastic template 620 as a suction unit that generates negative pressure for sucking the recording medium on the plastic template 620 through the suction hole 622 and the belt hole 165.

  Further, the suction holes 622 on the upper surface of the plastic template 620 are expanded on the upper surface side of the plastic template 620, so that a large number of recesses 621 that communicate with the suction holes 622 are defined on the upper surface of the plastic template 620. In the present embodiment, the recess 621 is defined independently of other adjacent recesses to form a minute space divided on the upper surface of the plate. These minute spaces have a so-called staggered arrangement, and their ranges do not coincide with each other in the direction perpendicular to the transport direction. In order to prevent this range from matching, a staggered arrangement is employed in this embodiment, but for example, the area and position of the recesses may be changed alternately.

(Configuration of ink mist adhesion prevention mechanism)
In the present embodiment, the platen belt 160 is provided with an ink mist adhesion prevention mechanism. FIGS. 6A and 6B are explanatory views schematically showing the operation of an ink mist adhesion preventing mechanism that is generated when ink is ejected from the image forming unit. FIG. 6A is a side cross-sectional view, and FIG. Is shown.

  As shown in FIG. 6, the ink mist adhesion preventing mechanism has a plurality of holes formed in the platen belt 160 that moves on the transport path surface facing the ink head 110 a, and a belt hole 165 that penetrates the front and back of the platen belt 160, and the belt A part of the hole 165 has an expanded part 166 that is expanded. In the present embodiment, the expanding portion 166 expands on the lower surface side of the platen belt 160 and has a convex cross section as shown in FIG. 6A, and has a shape on the lower surface side of the platen belt 160. As shown in FIG. 4B, the belt hole 165 and the expanded portion 166 are concentric.

  As indicated by arrows in FIG. 6, ink mist generated when ink is ejected from the ink head 110a passes through the belt hole 165 due to the negative pressure generated by the suction fan 650 provided at the lower part of the plastic template. Sucked. When the ink mist passes through the belt hole 165, a part of the ink mist is attached to the space of the expanding portion 166 and stored.

  Here, as the expansion part 166, various structures can be considered as shown in FIGS. Hereinafter, it demonstrates for every figure. Each drawing in FIG. 7 is a side view of the platen belt 160 and shows a position where the spread portion 166 is formed on the platen belt 160.

  More specifically, as shown in FIG. 7A, the expanded portion 166 can be a space expanded inside the platen belt 160 in the middle of the belt hole 165. In this case, the ink mist sucked from the surface of the platen belt 160 is held in the middle of the belt hole 165 and does not reach the back surface.

  Further, as shown in FIG. 7B, the expanded portion 166 can be a space expanded on the surface side of the platen belt 160. In this case, the ink mist is held on the surface of the platen belt 160, and the held ink can be transferred to the back surface of the recording medium while being dispersed in the widened area of the belt hole 165. it can. Since the amount of ink mist generated at one time is very small, it is dispersed and transferred to the back surface of the recording medium, so that the image quality is not affected.

  Further, as shown in FIG. 7C, the expanded portion 166 can be a space expanded on both the front and back surfaces of the platen belt 160. In this case, by holding the ink mist on the front and back of the platen belt 160, the ink mist is transferred to the back surface of the recording medium on the front surface side, and is held in the expanding portion on the back surface side.

  Next, FIG. 8 is a bottom view of the platen belt 160 and shows an example of changing the shape of the expanded portion. More specifically, the expanded portion can be a groove extending on the belt surface in communication with another adjacent expanded portion.

  For example, as shown in FIG. 8A, the expanded portion can be communicated in the transport direction to form a groove 167. Further, the groove 167 can be communicated in a direction (main scanning direction) orthogonal to the transport direction as shown in FIG. 5B, and further, in the transport direction as shown in FIG. Alternatively, it may be formed in a lattice shape that communicates with both in the main scanning direction.

  Furthermore, a configuration for holding ink can be added to the expanding portion 166 and the groove 167. FIG. 9 is an explanatory diagram of the expanding portion.

  As shown in the figure, a raised member such as a felt as shown in FIG. 9A may be attached to the space inside the expanded portion, as shown in FIG. Alternatively, a porous member may be attached.

  Furthermore, in the embodiment described above, the belt holes 165 having the expanded portions are uniformly distributed over the entire surface of the platen belt 160. However, the present invention is not limited to this, and for example, as shown in FIG. As described above, belt holes that do not have an expanded portion are distributed in the area A1 where the recording medium passes frequently, and the expanded portions are provided in the area A2 on both sides of the platen belt 160 where mist is likely to occur. Then, the distribution of the expanded portion may be changed according to the region on the belt, such as distributing belt holes having a mist holding function. Thereby, in the area A1 in the center of the belt, when the widened portion is provided on the lower surface of the belt, the grip with the driving roller is prevented from being reduced, and the effect of mist holding is enhanced in the area A2 where mist is likely to occur. Can do.

(Action / Effect)
According to this embodiment, floating mist in the printing apparatus that is generated when ink is ejected from the ink head 110 a passes through the belt hole 165 provided in the platen belt 160, thereby causing the platen belt 160 to move. It is sucked down.

  At this time, since the widened portion 166 provided in the belt hole 165 is a concave portion that does not come into contact with the driving roller 161, the driven roller 162, and the recording medium, when the floating mist passes through the belt hole 165, the widened portion 166. It is possible to prevent mist from adhering to the driving roller 161 and the platen belt 160. In addition, when the groove 167 is connected to the expanded portion 166, the volume of the expanded portion 166 can be maximized, and more ink mist can be adhered and held.

(A) is a block diagram showing an outline of a recording medium conveyance path of the printing apparatus 100 according to the present embodiment, and (b) schematically shows a sheet feeding system conveyance path FR, a normal path CR, and a reverse path SR. It is explanatory drawing shown in. It is explanatory drawing which shows the image formation path | route in which the image formation which concerns on embodiment is performed from a side. (A) is explanatory drawing which shows the head holder arrange | positioned above an image form path | route from the downward direction, (b) is explanatory drawing which expands and shows the side cross section of a head holder. It is a perspective view which shows the head holder which concerns on embodiment from upper direction. FIG. 6 is a top view illustrating a recording medium transport mechanism of an image forming path according to the embodiment with a part cut away. 4A and 4B are explanatory views schematically showing the operation of an ink mist adhesion prevention mechanism that is generated when ink is ejected from the image forming unit according to the embodiment. FIG. 5A is a side cross-sectional view, and FIG. Show. FIG. 4 is a side sectional view of the belt platen according to the embodiment, and shows the formation position of the expanded portion in the platen belt 160. It is a bottom view of the belt platen which concerns on embodiment, and shows the example of a change of the shape of an expansion part. It is explanatory drawing of the expansion part which concerns on embodiment. It is explanatory drawing which shows distribution of the expansion part on the belt platen which concerns on the example of a change of embodiment. FIG. 10 is an explanatory diagram of ink mist generated when ink is ejected from an image forming unit in the prior art.

Explanation of symbols

CR: Normal path DR: Paper discharge path FR ... Paper feed system transport path R ... Registration part SR ... Reverse path 10 ... Recording medium 100 ... Printing device 110 ... Head unit 110a ... Ink head 111 ... Main direction flow path 112 ... Sub direction Flow path 120 ... Side paper feed tray 130 ... Paper feed tray 140 ... Discharge port 150 ... Discharge tray 160 ... Platen belt 161 ... Drive roller 162 ... Driving roller 165 ... Belt hole 166 ... Expanded portion 167 ... Groove 170,172 ... Switching mechanism 220 ... Side paper feed drive unit 230a, 230b ... Tray drive unit 240 ... Registration drive unit 250 ... Belt drive unit 260 ... First upper surface transport drive unit 265 ... Second upper surface transport drive unit 270 ... Upper surface discharge drive unit 281 ... Reverse drive unit 330 ... Calculation processing unit 340 ... Operation panel 500 ... Head holder 500a ... Head holder Over surface 500b ... attachment openings 510 ... stepped guide rollers 510a ... upstream guide roller 510b ... downstream guide rollers 520 ... bearing part 620 ... platen 621 ... recess 622 ... suction holes 650 ... Suction Fan

Claims (5)

A transport mechanism of a printing apparatus that forms an image on the recording medium by ejecting ink from an ink head onto a recording medium transported on a transport path,
A transport belt that moves on the transport path surface facing the ink head is disposed, and the transport belt is provided with a number of belt holes penetrating the front and back of the transport belt,
A conveying mechanism of a printing apparatus, wherein the belt hole is formed with a widened portion that is partially expanded.   The conveyance mechanism of the printing apparatus according to claim 1, wherein the expansion portion is a concave portion that is expanded on a back surface side of the conveyance belt.   The conveyance mechanism of the printing apparatus according to claim 1, wherein the expansion portion is a concave portion that is expanded on a surface side of the conveyance belt.   The conveyance mechanism of the printing apparatus according to claim 1, wherein the expansion portion is a space expanded in the conveyance belt in the middle of the belt hole.   The transport mechanism of the printing apparatus according to claim 1, wherein the expanding portion communicates with another adjacent expanding portion.