JP2019093591A - Inkjet printer - Google Patents

Abstract

Disclosed is an ink jet printing apparatus capable of more efficiently collecting an ink mist collecting mechanism and extending a maintenance cycle. A transport mechanism that has a plurality of belt suction holes 26a arranged in the transport direction of a print medium P, sucks and attracts the print medium P, and the print medium P transported by the transport mechanism. An ink jet head 29 that performs printing by ejecting ink, and is provided on both the downstream side in the transport direction of the print medium of the ink jet head 29, the upstream side in the transport direction, or the downstream side and the upstream side in the transport direction. Suction sections 42 and 43 for sucking the ink mist, and a control section for controlling the suction sections 42 and 43. The control section controls the suction sections 42 and 43 according to the transport position of the print medium P by the transport mechanism. Control the timing of suction. [Selection] Figure 7

Description

  BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to an inkjet printing apparatus that performs printing by discharging ink to a printing medium.

  2. Description of the Related Art Conventionally, an inkjet printing apparatus has been proposed in which printing is performed by discharging an ink from an inkjet head to a print medium while conveying the print medium made of paper or film.

In the ink jet printing apparatus, the ink discharge from the ink jet head generates ink mist in the form of mist. Ink mist causes contamination inside the apparatus. In addition, the ink mist may adhere to the paper to be printed to reduce the printing image quality.

  In order to prevent the contamination in the apparatus due to the generation of the ink mist and the deterioration of the printing image quality, an ink jet printing apparatus having a mechanism for collecting the ink mist has been proposed. For example, Patent Document 1 proposes that a mechanism for sucking and collecting ink mist is provided on the downstream side of the ink jet head in the print medium conveyance direction.

  Further, in Patent Document 2, the ink mist generated between the head holder and the transport unit for transporting the print medium is generated by generating an air flow in a box-shaped head holder in which a plurality of inkjet heads are installed, There has been proposed a mechanism for collecting in the head holder via a gap formed between the head holder and the ink jet head.

JP, 2015-134496, A JP, 2016-155316, A

  However, as described in Patent Document 1, if the ink mist is recovered only by the recovery mechanism provided on the downstream side of the printing medium conveyance direction of the ink jet head, maintenance frequency of the recovery mechanism increases. I will.

  Further, in Patent Document 2, it is proposed that the ink mist be collected in the head holder and the ink mist be collected from the suction holes of the transport belt of the print medium, but for example, the ink mist is collected in the head holder If the recovery mechanism is operated at all times, most of the ink mist is recovered in the head holder, which may also increase the frequency of maintenance.

  SUMMARY OF THE INVENTION In view of the above-described circumstances, the present invention has an object to provide an ink jet printing apparatus capable of dispersing an ink mist recovery mechanism, recovering the ink mist more efficiently, and extending the maintenance cycle. .

  The inkjet printing apparatus according to the present invention has a plurality of suction holes arranged in the conveyance direction of the print medium, and a conveyance unit that suctions and adsorbs the print medium for conveyance, and an ink for the print medium conveyed by the conveyance unit The ink jet head is provided to the downstream side of the printing medium in the conveyance direction of the printing medium, the upstream side of the conveyance direction, or both the downstream side and the upstream side of the printing medium. And a control unit that controls the suction unit, and the control unit controls the timing of suction by the suction unit according to the transport position of the print medium by the transport unit.

  According to the inkjet printing apparatus of the present invention, a suction unit is provided to the conveyance direction downstream side, the conveyance direction upstream side of the printing medium of the ink jet head, or both the downstream side and the conveyance direction By controlling the timing of suction by the suction unit according to the conveyance position of the printing medium, the ink mist can be collected more efficiently by the conveyance unit having suction holes and the suction unit, and the maintenance cycle can be extended. Can.

The figure which shows schematic structure of one Embodiment of the inkjet printing apparatus of this invention Perspective view of the head holder Top view of the head holder Enlarged view of the configuration around the inkjet head Block diagram showing a schematic configuration of a control system of the ink jet printing apparatus according to the first embodiment Flow chart for explaining the operation of the ink jet printing apparatus of the first embodiment Explanatory drawing for demonstrating the operation | movement of the inkjet printing apparatus of 1st Embodiment Block diagram showing a schematic configuration of a control system of the ink jet printing apparatus according to the second embodiment Flow chart for explaining the operation of the ink jet printing apparatus of the second embodiment Explanatory drawing for demonstrating the operation | movement of the inkjet printing apparatus of 2nd Embodiment

  Hereinafter, a first embodiment of the ink jet printing apparatus of the present invention will be described in detail with reference to the drawings. The ink jet printing apparatus of the present embodiment is characterized by the control of a suction unit for sucking the ink mist generated by the discharge of the ink. First, the entire configuration of the ink jet printing apparatus will be described. FIG. 1 is a schematic block diagram of the ink jet printing apparatus 1 of the present embodiment. In addition, the upper and lower, right and left shown by the arrow in FIG.

  As shown in FIG. 1, the inkjet printing apparatus 1 of the present embodiment includes a sheet feeding unit 10, an image forming unit 20, and a sheet discharging unit 30.

  The sheet feeding unit 10 feeds a sheet of paper 11 on which a print medium P such as paper or film is loaded and the sheet of print medium P stacked on the sheet feeder 11 one sheet at a time from a top to a registration roller 15 described later. Primary sheet feeding roller 12 which abuts against the registration roller 15 and the registration roller 15 which delivers the print medium P fed by the primary sheet feeding roller 12 to the image forming section 20 with a predetermined sheet interval. Have.

  The primary sheet feeding roller 12 includes a pickup roller 13 and a sheet feeding roller 14. The pickup roller 13 and the sheet feeding roller 14 rotate counterclockwise in FIG. 1, whereby the print medium P fed from the sheet feeding table 11 is conveyed to the registration roller 15. Then, after the leading end of the print medium P abuts on the registration roller 15, the registration roller 15 rotates at a preset timing, and the print medium P is conveyed toward the image forming unit 20.

  The image forming unit 20 includes four line heads 27 and a conveyance mechanism 21 (corresponding to the conveyance unit of the present invention). Each line head 27 extends in a direction perpendicular to the transport direction of the print medium P, and discharges ink on the print medium P transported by the transport mechanism 21 to perform printing. The four line heads 27 are arranged at predetermined intervals along the transport path of the print medium P as shown in FIG. The four line heads 27 eject ink of different colors (for example, black, cyan, magenta and yellow).

  Each line head 27 has two head rows in which three ink jet heads are arranged at equal intervals in the direction orthogonal to the conveyance direction of the print medium P, and the two head rows have a half pitch in the orthogonal direction. It is arranged and arranged to be offset by a minute.

  Each inkjet head 29 of each line head 27 is installed on a head holder 28. FIG. 2 is a perspective view of the head holder 28 as viewed obliquely from above, and FIG. 3 is a top view of the head holder 28.

  The head holder 28 is formed of a box-shaped support member as shown in FIG. 2, and a plurality of installation holes in which the ink jet heads 29 of the line heads 27 are fitted and installed on the bottom surface of the head holder 28 28a is formed. The installation holes 28 a are through holes, and are formed so that the ink ejection surfaces of the respective ink jet heads 29 are disposed so as to be exposed outside the bottom surface of the head holder 28.

  Four dotted-line squares shown in FIG. 3 indicate the range of the installation holes 28 a in which the six inkjet heads 29 of each line head 27 are disposed. The six inkjet heads 29 of each line head 27 are respectively disposed in the six installation holes 28 a within the dotted square.

  Further, as shown in FIGS. 2 and 3, holder suction holes 28b and 28c are formed on the upstream side and the downstream side of the transport direction of the print medium P in the installation holes 28a. The holder suction holes 28 b and 28 c are through holes formed corresponding to suction ports of suction portions 42 and 43 described later. The ink mist sucked by the suction units 42 and 43 is collected in the suction units 42 and 43 via the holder suction holes 28 b and 28 c.

  Returning to FIG. 1, the transport mechanism 21 includes the transport belt 26, the drive roller 22, the driven rollers 23, 24, 25, the platen 40 and the like. The transport mechanism 21 transports the print medium P transported from the paper feed unit 10 while maintaining a constant speed in a state where the print medium P transported from the paper feed unit 10 is attracted and adsorbed onto the transport belt 26. After being applied, the printed print medium P is conveyed to the paper discharge unit 30.

  The platen 40 is a plate member provided opposite to the bottom surface of the head holder 28. A plurality of platen suction holes 40 a are formed in a range where the conveyance belt 26 of the platen 40 passes. The platen suction holes 40 a are through holes, and are formed in a two-dimensional shape in the conveyance direction of the print medium P and in the direction orthogonal to the conveyance direction.

  Below the platen 40, a fan mechanism 41 is provided as shown in FIG. The fan mechanism 41 generates a suction force in the platen suction hole 40 a of the platen 40 by rotating the fan and applying negative pressure to the space below the platen 40.

  The conveying belt 26 is an annular endless belt which is stretched over the driving roller 22, the driven rollers 23, 24, 25 and the platen 40 and slides on the platen 40. The transport belt 26 is made of a material such as rubber or resin that has plasticity and generates appropriate friction with the print medium P. The driven rollers 23, 24 and 25 support the conveying belt 26 together with the driving roller 22, and follow the driving roller 22 via the conveying belt 26.

  FIG. 4 is an enlarged view of a configuration around one ink jet head 29. As shown in FIG. As shown in FIG. 4, the transport belt 26 has a plurality of belt suction holes 26 a two-dimensionally arranged in the transport direction of the print medium P and the direction orthogonal to the transport direction. As described above, by operating the fan mechanism 41 to make the space under the platen 40 negative pressure, a suction force is generated in the platen suction hole 40 a of the platen 40, whereby the transport belt slides on the platen 40. The suction force is also generated in the belt suction holes 26a of 26.

  The print medium P is sucked and adsorbed by the suction force generated in the belt suction holes 26a, and the print medium P is transported as the transport belt 26 moves. Further, the belt suction holes 26a not blocked by the print medium P have a function of suctioning ink mist by the suction force. The ink mist sucked by the belt suction holes 26a is collected in a collection mechanism (not shown).

  Further, as shown in FIG. 4, suction sections 42 and 43 for suctioning ink mist are provided on the transport direction upstream side and the transport direction downstream side of the inkjet head 29. The suction units 42 and 43 are disposed above the holder suction holes 28b and 28c of the head holder 28, and have a suction mechanism including, for example, a fan. The suction units 42 and 43 are configured to be able to adjust suction timing and suction air volume by control of a control unit 60 described later. The timing of suction and the suction air volume will be described in detail later.

  Further, as shown in FIG. 4, a pair of contact preventing rollers 50 is provided between the inkjet head 29 and the transport belt 26 on the upstream side and downstream side of the inkjet head 29 in the transport direction. The contact prevention roller pair 50 is a roller that prevents the print medium P from contacting the inkjet head 29. The contact prevention roller pair 50 is a roller extending in a direction orthogonal to the conveyance direction of the print medium P, and for each head row in which three inkjet heads 29 are arranged in a direction orthogonal to the conveyance direction of the print medium P It is provided. In FIG. 1, the contact preventing roller pair 50 is schematically illustrated.

  The paper discharge unit 30 includes a paper discharge tray 31, and sequentially stocks the printed print media P printed by the image forming unit 20 on the paper discharge tray 31.

  FIG. 5 is a block diagram showing a schematic configuration of a control system of the inkjet printing apparatus 1 of the present embodiment. The inkjet printing apparatus 1 of this embodiment is provided with the control part 60 which controls operation | movement of each part of the inkjet printing apparatus 1, as shown in FIG.

  The control unit 60 includes a central processing unit (CPU), a semiconductor memory, a hard disk, and the like. The control unit 60 executes a program stored in advance in a storage medium such as a semiconductor memory or a hard disk, and operates an electric circuit, whereby the paper feed unit 10, the transport mechanism 21, the inkjet head 29, the fan mechanism 41 and the discharge The paper unit 30 is controlled to convey the print medium P, and the line head 27 discharges the ink from the line medium 27 for printing. Furthermore, the control unit 60 controls the suction units 42 and 43 as described above, and thereby controls the suction operation of the ink mist.

  In addition, control unit 60 receives print job data including print data to be printed output from, for example, a printer driver installed in a computer, and controls inkjet head 29 etc. based on the received print job data. And print processing.

  In particular, the control unit 60 according to the present embodiment calculates the information of the ink ejection amount (ink ejection amount for one print medium P) per printing medium unit based on the print data included in the print job data, and The suction air volume of the suction units 42 and 43 is controlled based on the calculated information. More specifically, in the present embodiment, the printing rate is calculated as the information of the ink ejection amount per printing medium unit. The printing rate is the ratio of the area of the range to be actually printed to the entire printable range of one printing medium P.

  In the present embodiment, as described above, the printing rate is calculated as the information of the ink ejection amount per printing medium unit, but the invention is not limited thereto, and the printing density, the number of ink drops, and the like for each printing medium may be calculated. It may be used as information on the ink ejection amount per printing medium unit. Further, both the printing rate and the printing density may be used as the information of the ink discharge amount per printing medium unit. The control of the suction units 42 and 43 based on the printing rate will be described in detail later.

  Next, the operation of the inkjet printing apparatus 1 of the present embodiment will be described with reference to the flowchart shown in FIG. 6 and FIG. Here, control of the suction units 42 and 43 in the inkjet printing apparatus 1 will be mainly described.

  First, print job data output from a computer or the like is received by the control unit 60 (S10). The control unit 60 calculates the printing rate for each print medium based on the received print job data (S12).

  Then, under the control of the control unit 60, the sheet feeding from the sheet feeding unit 10 is started, and the conveyance of the print medium P by the conveyance mechanism 21 is started (S14). Then, the control unit 60 starts suctioning by the suction units 42 and 43 when the print medium P is conveyed to the position illustrated in FIG. 7A. Specifically, the control unit 60 sets the print medium P to a position where all the belt suction holes 26a in the range R between the rollers of the contact prevention roller pair 50 including the area directly under the inkjet head 29 are blocked by the print medium P. Is determined (S16). If the print medium P is transported to a position where all the belt suction holes 26a in the range R are blocked by the print medium P (S16, YES), suction is determined. The suction by the parts 42 and 43 is started (S18).

  When all the belt suction holes 26a in the range R are blocked by the print medium P, the space below the ink jet head 29 is a space surrounded by the ink jet head 29, the print medium P, and the contact preventing roller pair 50, Although the ink mist can not be collected from the belt suction holes 26 a of the transport belt 26, as described above, the ink mist is collected by the suction units 42 and 43 which are not affected by the presence or absence of the printing medium P. It is possible to properly collect the staying ink mist.

  Then, while the print medium P is being conveyed continuously (S20, NO), all the belt suction holes 26a in the range R are blocked by the print medium P, and the suction unit 42, 43 continues. Suction by (S16, S18) is continued.

  Further, when the print medium P is conveyed and conveyed to the position shown in FIG. 7B, that is, when it is conveyed to the position where at least one belt suction hole 26a within the range R is opened (S16, NO), The control unit 60 switches control of the suction units 42 and 43 in accordance with the printing rate of the print medium P being conveyed.

  Specifically, when the printing rate of the print medium P is less than a preset threshold (S22, YES), the control unit 60 stops the suction by the suction units 42 and 43 (S24). At this time, the ink mist is absorbed by the belt suction holes 26 a and collected.

  Thus, by stopping the suction by the suction units 42 and 43 and collecting the ink mist by the belt suction holes 26a, it is possible to prevent the ink mist from being collected biased to the suction units 42 and 43, and suction The maintenance cycle of the units 42 and 43 can be extended.

  On the other hand, when the printing rate of the print medium P is equal to or more than the threshold, the control unit 60 continues suction without stopping suction by the suction units 42 and 43. However, as for the suction air volume at this time, suction is performed with an air volume weaker than the suction air volume in the case where all the belt suction holes 26a in the range R are blocked by the print medium P (S26). That is, when the printing rate of the print medium P is high, the amount of the ink mist also increases, so suctioning by the suction portions 42 and 43 as well as the belt suction holes 26a is continuously performed. Thus, the ink mist can be properly collected.

  When the printing rate of the printing medium P is equal to or more than the threshold, the amount of ink mist increases as described above. Therefore, the suction air volume when all the belt suction holes 26a in the range R are blocked by the print medium P is also made stronger than the suction air volume when the printing rate of the print medium P is less than the threshold. desirable.

  When there is a print medium P to be conveyed next (S28, NO), the suction by the suction units 42 and 43 is stopped until the next print medium P is conveyed to the position shown in FIG. 7A (S24) Or suction with a weak suction air volume (S26) is continued.

  Then, when the next print medium P is conveyed to the position shown in FIG. 7A (S16, YES), suction by the suction units 42 and 43 is started again (S18). Then, similarly to the first print medium P, while the print medium P is continuously conveyed (S20, NO), suction by the suction units 42 and 43 is continued (S16, S18), and the next print medium When P is conveyed to the position shown in FIG. 7B (S16, NO), suction is performed by the suction units 42 and 43 in accordance with the printing rate of the next print medium P as in the case of the first print medium P. Stop (S24) or perform suction (S26) with a weak suction air volume.

  The processes from S16 to S28 are repeatedly performed until the conveyance of all print media P is completed, and the process is ended when the conveyance of all print media P is completed (S20, YES, S28, YES).

  The transport position of the print medium P is recognized by the control unit 60 based on a detection signal from a sheet detection sensor (not shown) and size information and print number information of the print medium P included in the print job data.

  Next, a second embodiment of the ink jet printing apparatus of the present invention will be described. In the inkjet printing apparatus 1 according to the first embodiment, the suction unit 43 is provided on the upstream side of the inkjet head 29 in the transport direction, and the suction unit 42 is provided on the downstream side in the transport direction. In the printing apparatus, a suction and exhaust unit 44 is provided instead of the suction unit 43 on the upstream side in the transport direction. The other configuration is the same as that of the ink jet printing apparatus 1 of the first embodiment.

  FIG. 8 is a block diagram showing the configuration of a control system of the ink jet printing apparatus according to the second embodiment. The suction / exhaust unit 44 sucks the ink mist as well as the suction unit 43 of the first embodiment, and discharges the ink mist toward the transport belt 26 side. The suction and exhaust unit 44 has a suction mechanism including a fan and the like and an exhaust mechanism. As a direction of exhaust of the suction / exhaust unit 44, it is desirable to be configured to exhaust toward the position immediately below the adjacent inkjet head 29. In the present embodiment, although the suction and exhaust unit 44 performs both suction and exhaust, the suction unit and the exhaust unit may be provided separately.

  Next, the operation of the ink jet printing apparatus according to the second embodiment will be described with reference to the flowchart shown in FIG. 9 and FIG. The control of the suction and exhaust unit 44 and the suction unit 42 in the ink jet printing apparatus according to the second embodiment will be mainly described here.

  First, print job data output from a computer or the like is received by the control unit 60 (S40).

  Then, the sheet feeding from the sheet feeding unit 10 is started under the control of the control unit 60, and the conveyance of the print medium P by the conveyance mechanism 21 is started (S42). Then, when the print medium P is conveyed to the position shown in FIG. 10A, the control unit 60 starts suctioning by the suction and exhaust unit 44 and the suction unit 42. Specifically, the control unit 60 sets the print medium P to a position where all the belt suction holes 26a in the range R between the rollers of the contact prevention roller pair 50 including the area directly under the inkjet head 29 are blocked by the print medium P. Is determined (S44). If the print medium P is transported to a position where all the belt suction holes 26a in the range R are blocked by the print medium P (S44, YES), suction is determined. The suction by the exhaust unit 44 and the suction unit 42 is started (S46).

  Then, while the print medium P is being conveyed continuously (S 48, NO), all the belt suction holes 26 a in the range R are blocked by the print medium P, and the suction exhaust unit 44 and the control unit 60 continue. The suction by the suction unit 42 is continued (S44, S46).

  Further, when the print medium P is conveyed and is conveyed to the position shown in FIG. 10B, that is, when it is conveyed to the position where at least one belt suction hole 26a within the range R is opened (S44, NO), The control unit 60 stops the suction by the suction and exhaust unit 44 and switches to the exhaust, and performs the exhaust by the suction and exhaust unit 44 and the suction by the suction unit 42 (S50). The space between the rollers of the contact prevention roller pair 50 can be pressurized by switching the suction and exhaust unit 44 to the exhaust at the timing when the belt suction holes 26a in the range R are opened as described above, whereby the downstream side in the transport direction The suction and recovery power of the suction portion 42 and the belt suction hole 26 a of the conveyance belt 26 can be improved. Further, the ink mist can be collected in a well-balanced manner by the suction portion 42 and the belt suction hole 26 a of the conveyance belt 26.

  Then, when there is a print medium P to be conveyed next (S 48, NO), the exhaust by the suction and exhaust unit 44 and the suction unit 42 are performed until the next print medium P is conveyed to the position shown in FIG. 10A. Continue suctioning.

  Then, when the next print medium P is conveyed to the position shown in FIG. 10A (S44, YES), the exhaust by the suction and exhaust unit 44 is switched to suction, and suction by the suction and exhaust unit 44 and the suction unit 42 is started again. . Then, similarly to the first print medium P, while the print medium P is continuously conveyed (S 48, NO), suction by the suction and exhaust unit 44 and the suction unit 42 is continued (S 44, S 46), and the next When the first print medium P is conveyed to the position shown in FIG. 10B (S44, NO), the suction by the suction / exhaust unit 44 is stopped and switched to the exhaust as in the case of the first print medium P, The exhaust by the unit 44 and the suction by the suction unit 42 are performed (S50).

  The processes from S44 to S50 are repeatedly performed until the conveyance of all print media P is completed, and the process is ended when the conveyance of all print media P is completed (S48, YES).

  In the inkjet printing apparatus 1 according to the first embodiment, as in the inkjet printing apparatus according to the second embodiment, the inkjet head 29 discharges air toward the transport belt 26 on the upstream side in the transport direction of the print medium P. An exhaust unit may be provided. Then, the print medium P is conveyed to a position where at least one belt suction hole 26a in the range R opens, and the printing rate is equal to or more than the threshold, and suction is performed by the suction unit 42 with a weak suction air volume. In this case, exhaust may be performed by the exhaust unit. As a result, the suction and recovery power of the suction portion 42 on the downstream side in the transport direction and the belt suction holes 26 a of the transport belt 26 can be improved. Further, the ink mist can be collected in a well-balanced manner by the suction portion 42 and the belt suction hole 26 a of the conveyance belt 26.

Further, the following appendices are disclosed regarding the inkjet printing apparatus of the present invention.
(Supplementary note)

  In the ink jet printing apparatus according to the present invention, the control unit is controlled by the suction unit when the print medium is conveyed to a position where all the suction holes in a preset range including the area directly below the ink jet head are blocked by the print medium. When suction is performed and the print medium is conveyed to a position where at least one suction hole within a preset range is opened, suction by the suction unit can be stopped.

  In the inkjet printing apparatus according to the present invention, the control unit is configured to receive information on the ink ejection amount per printing medium unit when the printing medium is conveyed to a position where at least one suction hole within a preset range is opened. If it is less than the preset threshold, the suction by the suction unit is stopped, and if the information on the ink discharge amount is equal to or more than the threshold, the print medium is conveyed to a position where the suction hole is blocked by the print medium Suction can be performed with a suction air volume weaker than the suction air volume of the suction part in the case where

  In the inkjet printing apparatus according to the present invention, an exhaust unit for exhausting air toward the transport unit side can be provided on the upstream side of the inkjet head in the transport direction of the print medium, and the control unit is at least within a preset range. When the print medium is conveyed to a position where one suction hole opens, and the information on the ink discharge amount is equal to or more than the threshold value, and the suction unit performs suction with a weak suction air volume, the exhaust unit The exhaust can be done by

  In the inkjet printing apparatus according to the present invention, a suction unit is provided on the upstream side and the downstream side of the print medium in the transport direction of the printing medium of the inkjet head, and the exhaust is performed toward the transport side on the upstream side of the transport direction The control unit may be arranged upstream of the transport direction when the print medium is transported to a position where all the suction holes in a preset range including the area directly below the inkjet head are blocked by the print medium. The suction unit provided on the side and the conveyance direction downstream side performs suction, and when the print medium is conveyed to a position where at least one suction hole within a preset range opens, the exhaust unit evacuates Suction can be performed by the suction unit provided on the downstream side in the transport direction.

  In the ink jet printing apparatus according to the present invention, the contact preventing roller which prevents the printing medium from contacting the ink jet head between the ink jet head and the conveyance section on the upstream side and the downstream side of the ink jet head in the conveyance direction. A pair can be provided, and the preset range can be set based on the distance between the pair of contact prevention rollers.

Reference Signs List 1 inkjet printing apparatus 10 sheet feeding unit 11 sheet feeding table 12 primary sheet feeding roller 13 pickup roller 14 sheet feeding roller 15 registration roller 20 image forming unit 21 conveying mechanism 22 driving roller 23, 24, 25 driven roller 26 conveying belt 26a belt Suction hole 27 Line head 28 Head holder 28a Installation hole 28b, 28c Holder suction hole 29 Ink jet head 30 Discharge part 31 Discharge stand 40 Platen 40a Platen suction hole 41 Fan mechanism 42, 43 Suction part 44 Suction exhaust part 50 Contact prevention roller Pair 60 control unit P print medium R range

Claims (6)

A transport unit that has a plurality of suction holes arranged in the transport direction of the print medium, and transports the print medium by suction and suction;
An ink jet head that discharges ink on the print medium conveyed by the conveyance unit to perform printing;
A suction unit provided on the downstream side of the print medium in the transport direction of the printing head, the upstream side in the transport direction, or both the downstream side and the upstream side of the transport direction and for sucking ink mist generated by the discharge of the ink;
And a control unit that controls the suction unit,
An inkjet printing apparatus, wherein the control unit controls timing of suction by the suction unit in accordance with a conveyance position of the print medium by the conveyance unit.   The control unit performs suction by the suction unit when the print medium is conveyed to a position where all the suction holes in a preset range including the area directly below the inkjet head are closed by the print medium. The inkjet printing apparatus according to claim 1, wherein the suction by the suction unit is stopped when the printing medium is conveyed to a position where at least one suction hole within the preset range is opened.   When the print medium is conveyed to a position where at least one suction hole within the preset range is opened, the control unit sets in advance information on the ink discharge amount per print medium unit. When it is less than the threshold, the suction by the suction unit is stopped, and when the information of the ink discharge amount is the threshold or more, the print medium is moved to the position where the suction hole is closed by the print medium The inkjet printing apparatus according to claim 2, wherein the suction is performed with a suction air volume weaker than the suction air volume of the suction unit when the ink is being conveyed. An exhaust unit for exhausting air toward the transport unit side is provided on the upstream side of the inkjet head in the transport direction of the print medium,
The control unit is configured to convey the print medium to a position where the at least one suction hole within the preset range is opened, and the information on the ink discharge amount is equal to or more than the threshold value. 4. The ink jet printing apparatus according to claim 3, wherein the air is exhausted by the exhaust unit when the suction unit performs suction with the weak suction air volume. The suction unit is provided on the conveyance direction upstream side and the conveyance direction downstream side of the printing medium of the ink jet head, and an exhaust unit for exhausting toward the conveyance unit side is provided on the conveyance direction upstream side of the ink jet head. And
When the print medium is conveyed to a position where all the suction holes in a preset range including the area directly below the inkjet head are closed by the print medium, the control unit is configured to be upstream in the conveyance direction And, when the print medium is conveyed to a position where at least one of the suction holes within the preset range is opened, suction is performed by a suction unit provided on the downstream side in the conveyance direction. The ink jet printing apparatus according to claim 1, wherein the air is exhausted by a unit and suction is performed by a suction unit provided on the downstream side in the transport direction. A pair of contact prevention rollers for preventing the printing medium from contacting the ink jet head is provided between the ink jet head and the conveyance section, on the upstream side and the downstream side of the ink jet head in the conveyance direction. Provided,
The ink jet printing apparatus according to any one of claims 2 to 5, wherein the preset range is set based on the distance between the pair of contact preventing rollers.

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