JP6506979B2 - Ink jet printer - Google Patents

Description

  The present invention relates to an inkjet printing apparatus that ejects ink from an inkjet head to print.

  There is known a line-type ink jet printing apparatus which discharges ink from a fixed ink jet head onto a sheet while printing the sheet while conveying the sheet.

  In the line-type inkjet printing apparatus, as the printing speed increases, the driving frequency of the inkjet head increases and the calorific value of the inkjet head increases. Further, also when using an inkjet head with high printing resolution in which the piezoelectric elements are arranged at high density, the amount of heat generation of the inkjet head is increased. On the other hand, in order to use the head driver IC below the rated temperature, it is necessary to cool the ink jet head to suppress the temperature rise.

  Then, the technique which cools an inkjet head by sending a cooling air by a fan is known (for example, refer patent document 1).

JP, 2010-264752, A

  In the technique of cooling the inkjet head by the above-described fan, the air flow from the fan leaks to the space below the head holder from the gap between the opening of the head holder on which the inkjet head is attached and the inkjet head.

  Below the head holder, an air flow (conveying air flow) is generated due to sheet conveyance. Turbulence may occur due to the collision between the transport air flow and the air flow leaking from the gap between the opening of the head holder and the inkjet head described above. This turbulent flow scatters the ink mist generated by the ink discharge from the ink jet head in various directions. The ink mist scattered in various directions adheres to various places in the apparatus and paper, and causes stains in the apparatus and dirt on printed matter.

  The present invention has been made in view of the above, and it is an object of the present invention to provide an ink jet printing apparatus capable of reducing stains in the apparatus and stains of printed matter.

  In order to achieve the above object, a first feature of an inkjet printing apparatus according to the present invention is a transport unit for transporting a print medium, an inkjet head for discharging ink onto the print medium transported by the transport unit, and the inkjet A head having a mounting opening to which the head is attached via a gap, and a head holder of a box for holding the ink jet head, and a cooling air flowing from the upstream side to the downstream side in the transport direction of the print medium is generated in the head holder And a cooling unit for cooling the inkjet head.

  A second feature of the inkjet printing apparatus according to the present invention is that the inkjet printing apparatus further includes an ink mist recovery unit which is disposed downstream of the transport unit in the transport direction and recovers the ink mist.

  According to a third aspect of the inkjet printing apparatus of the present invention, the cooling unit sprays air from the upstream side of the head holder in the transport direction to the inkjet head in the head holder, and the cooling unit in the transport direction A suction unit for suctioning air from the head holder on the downstream side of the head holder, wherein the blowing wind by the blowing unit is stronger than the suction wind by the suction unit.

  According to the first aspect of the inkjet printing apparatus of the present invention, the cooling air from the cooling unit flows from the upstream side to the downstream side in the print medium conveyance direction. As a result, the cooling leakage air flow generated by the cooling air leaking downward from the gap between the mounting opening and the inkjet head flows in the same direction as the conveyance air flow generated by the conveyance of the print medium by the conveyance unit. For this reason, it is possible to suppress the occurrence of turbulent flow due to the collision of the air flows and to suppress the diffusion of the ink mist due to the turbulent flow. As a result, it is possible to reduce the contamination in the apparatus and the contamination of the printed matter.

  According to the second aspect of the inkjet printing apparatus in accordance with the present invention, the ink mist recovery unit recovers the ink mist induced to the downstream side of the transport unit by the transport airflow and the cooling leakage airflow. Thus, the ink mist can be efficiently collected without providing a mechanism for inducing the ink mist.

  According to the third aspect of the inkjet printing apparatus of the present invention, since the blowing wind by the blowing section is stronger than the suction wind by the suction section, the cooling leakage air flow becomes stronger, and the ink mist becomes stronger along the print medium conveyance direction. Can be guided. As a result, the collection efficiency of the ink mist can be improved.

It is a block diagram showing composition of an ink jet printing device concerning an embodiment. It is a schematic block diagram of the conveyance part of the inkjet printing apparatus shown in FIG. 1, a printing part, and an ink mist collection | recovery part. It is a top view of the printing part of the ink jet printing apparatus shown in FIG. It is a disassembled perspective view of the printing part of the inkjet printing apparatus shown in FIG. It is sectional drawing along the AA of FIG. It is a figure which shows the cooling air in a head holder. It is explanatory drawing of the airflow in the space between a head holder and a conveyance belt.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts or components are denoted by the same or equivalent reference numerals throughout the drawings.

  The embodiment shown below exemplifies an apparatus etc. for embodying the technical idea of this invention, and the technical idea of this invention is the material, shape, structure, arrangement etc. of each component. Does not specify the following. Various changes can be added to the technical idea of the present invention within the scope of the claims.

  FIG. 1 is a block diagram showing the configuration of the ink jet printing apparatus according to the embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a conveyance unit, a printing unit, and an ink mist collecting unit of the ink jet printing apparatus shown in FIG. FIG. 3 is a plan view of the printing unit. FIG. 4 is an exploded perspective view of the printing unit. FIG. 5 is a cross-sectional view taken along the line AA of FIG.

  In the following description, the direction orthogonal to the paper surface of FIG. 2 is taken as the front-rear direction, and the paper surface front direction is taken as the front. Further, the top, bottom, left, and right of the sheet of FIG. 2 are referred to as the top, bottom, left, and right directions. In FIG. 2, the direction from the left to the right is the conveyance direction of the sheet P, which is a print medium. In the following description, upstream and downstream mean upstream and downstream in the transport direction of the sheet P.

  As shown in FIG. 1, the inkjet printing apparatus 1 according to the present embodiment includes a transport unit 2, a printing unit 3, an ink mist collecting unit 4, and a control unit 5.

  The transport unit 2 transports the sheet P. As shown in FIGS. 1 and 2, the conveyance unit 2 includes a conveyance belt 11, a drive roller 12, driven rollers 13, 14 and 15, a belt motor 16, and a sheet suction fan 17.

  The conveyance belt 11 adsorbs and holds the sheet P and conveys it. The conveyance belt 11 is an annular belt which is wound around the driving roller 12 and the driven rollers 13 to 15. The conveyor belt 11 is formed with a plurality of belt holes 11a (see FIG. 7). The transport belt 11 sucks and holds the sheet P by the suction force generated in the belt hole 11 a by the driving of the sheet suction fan 17. The transport belt 11 transports the suctioned and held sheet P in the right direction by rotating in the clockwise direction in FIG.

  The drive roller 12 rotates the transport belt 11 in the clockwise direction in FIG.

  The driven rollers 13 to 15 support the transport belt 11 together with the drive roller 12. The driven rollers 13 to 15 are driven by the drive roller 12 via the conveyance belt 11. The driven roller 13 is disposed at the same height as the drive roller 12 and to the left of the drive roller 12. The driven rollers 14 and 15 are disposed at the same height below the drive roller 12 and the driven roller 13 so as to be separated in the left-right direction.

  The belt motor 16 rotationally drives the drive roller 12.

  The sheet suction fan 17 generates an air flow downward. As a result, the sheet suction fan 17 sucks air through the belt holes 11 a of the conveyance belt 11 to generate a negative pressure in the belt holes 11 a and causes the sheet P to be adsorbed onto the conveyance belt 11. The sheet suction fan 17 is disposed in an area surrounded by the annular conveyance belt 11.

  The printing unit 3 prints an image on the sheet P conveyed by the conveyance unit 2. The printing unit 3 is disposed above the conveyance unit 2. As shown in FIGS. 1 to 4, the printing unit 3 includes a head unit 21 and a cooling unit 22.

  The head unit 21 discharges ink on the sheet P conveyed by the conveyance unit 2 to print an image. The head unit 21 includes a plurality of inkjet heads 31 and a head holder 32.

  The inkjet head 31 has an ink ejection surface 31 a. The ink discharge surface 31 a is a lower surface of the inkjet head 31 facing the conveyance belt 11. A plurality of nozzles (not shown) disposed along the front-rear direction (main scanning direction) are opened in the ink ejection surface 31a. The ink jet head 31 ejects the ink supplied through the ink supply path (not shown) from the nozzles.

  The ink jet heads 31 are disposed in a staggered manner as shown in FIGS. 3 and 4. Specifically, four head rows each including three inkjet heads 31 arranged at equal intervals along the front-rear direction (main scanning direction) are arranged in parallel along the left-right direction. And each inkjet head 31 of each head row is arrange | positioned so that only a half pitch may shift | deviate in the front-back direction between adjacent head rows.

  The head holder 32 holds the inkjet head 31. The head holder 32 is formed of a hollow box-shaped box. As shown in FIGS. 4 and 5, the head holder 32 has a bottom plate 41, side plates 42 to 45, and a top plate 46.

  The bottom plate 41 holds and fixes the ink jet head 31. The bottom plate 41 is formed in a rectangular shape. The bottom plate 41 is provided with a mounting opening 41 a for mounting the ink jet head 31. The mounting openings 41 a are formed in the same number as the inkjet heads 31. The ink jet head 31 is inserted into and fixed to the attachment opening 41 a so that the ink discharge surface 31 a protrudes downward from the bottom plate 41.

  The mounting opening 41 a is a through hole larger in cross section along the horizontal surface of the inkjet head 31. Thereby, the mounting position and the angle of the ink jet head 31 can be adjusted. Since the mounting opening 41a is formed in this manner, as shown in FIG. 5, the inkjet head 31 is mounted to the mounting opening 41a with a gap.

  The side plates 42, 43, 44 and 45 form side walls on the front side, the left side, the rear side and the right side of the head holder 32, respectively. The side plates 42 to 45 are integrally formed, and are erected around the bottom plate 41.

  The left side plate 43 is formed with a plurality of ventilation holes 43a. The ventilating hole 43 a is an inlet of air into the head holder 32 when air is blown to the ink jet head 31 by the blowing unit 51 described later. The plurality of ventilation holes 43a are disposed along the front-rear direction.

  A plurality of ventilating holes 45 a are formed in the right side plate 45. The air vent 45 a is an outlet of air when air is sucked from the head holder 32 by the suction unit 52 described later. The plurality of ventilation holes 45a are disposed at positions facing the plurality of ventilation holes 43a of the left side plate 43, respectively.

  The top plate 46 is a lid that closes the opening at the upper end of the side wall formed of the side plates 42 to 45. The top 46 is formed in a rectangular shape.

  The cooling unit 22 cools the ink jet head 31 by generating in the head holder 32 cooling air that flows from the upstream side to the downstream side (left to right) in the transport direction of the sheet P. The cooling unit 22 includes a blowing unit 51 and a suction unit 52.

  The spray unit 51 sprays air on the inkjet head 31 in the head holder 32. The spray unit 51 is disposed on the left side of the head holder 32. That is, the blowing unit 51 blows air to the inkjet head 31 in the head holder 32 from the upstream side of the head holder 32 in the conveyance direction of the sheet P. The spray unit 51 includes a spray chamber 61 and a spray fan 62.

  The spray chamber 61 forms a flow path of air between the spray fan 62 and the head holder 32. The blowing chamber 61 is formed in a hollow shape elongated in the front-rear direction, which is a direction orthogonal to the conveyance direction of the sheet P. The spray chamber 61 is disposed on the left side plate 43 of the head holder 32. In the spray chamber 61, a plurality of spray holes 61a are formed.

  The spray hole 61 a is an outlet of air from the spray chamber 61 when the air is sprayed to the inkjet head 31. The spray holes 61 a are disposed at positions corresponding to the vent holes 43 a of the side plate 43. Thereby, the space in the spray chamber 61 and the space in the head holder 32 are communicated with each other through the spray hole 61a and the ventilating hole 43a.

  The blowing fan 62 blows air from one end of the blowing chamber 61 into the blowing chamber 61. As a result, the blowing fan 62 blows air to the inkjet head 31 in the head holder 32 through the blowing hole 61 a of the blowing chamber 61 and the ventilation hole 43 a of the side plate 43.

  The suction unit 52 sucks air from the head holder 32. The suction unit 52 is disposed on the right side of the head holder 32, which is the opposite side of the spray unit 51 across the head holder 32. That is, the suction unit 52 sucks air from the head holder 32 on the downstream side of the head holder 32 in the conveyance direction of the sheet P. The suction unit 52 includes a suction chamber 66 and a suction fan 67.

  The suction chamber 66 forms a flow path of air between the head holder 32 and the suction fan 67. The suction chamber 66 is formed in a hollow shape in a longitudinally elongated shape. The suction chamber 66 is disposed on the right side plate 45 of the head holder 32. A plurality of suction holes 66 a are formed in the suction chamber 66.

  The suction hole 66 a is an inlet of air to the suction chamber 66 when suctioning air from the head holder 32. The suction holes 66 a are disposed at positions corresponding to the vent holes 45 a of the side plate 45. Thus, the space in the suction chamber 66 and the space in the head holder 32 are in communication with each other via the suction hole 66a and the vent hole 45a.

  The suction fan 67 sucks air from one end of the suction chamber 66. Thereby, the suction fan 67 sucks air from the head holder 32 through the suction hole 66 a of the suction chamber 66 and the vent hole 45 a of the side plate 45.

  The ink mist recovery unit 4 recovers the ink mist. The ink mist recovery unit 4 is disposed downstream of the transport unit 2. The ink mist recovery unit 4 includes an ink mist suction fan 71 and a filter 72.

  The ink mist suction fan 71 sucks the air containing the ink mist flowing from the conveyance unit 2 on the downstream side of the conveyance unit 2.

  The filter 72 absorbs the ink mist in front of the ink mist suction fan 71. The filter 72 is made of a sponge or the like.

  The control unit 5 controls the operation of each unit of the inkjet printing apparatus 1. The control unit 5 includes a CPU, a RAM, a ROM, a hard disk and the like.

  Specifically, the control unit 5 controls the cooling unit 22 to cool the inkjet head 31 while discharging the ink from the inkjet head 31 while transporting the sheet P by the transport unit 2 at the time of printing.

  Next, the operation of the inkjet printing apparatus 1 will be described.

  When a print job is input, the control unit 5 causes the belt motor 16 to activate the drive roller 12. Thus, the circumferential drive of the transport belt 11 is started.

  Further, the control unit 5 activates the sheet suction fan 17. Thus, air is sucked by the sheet suction fan 17 through the belt hole 11a of the conveyance belt 11, and a negative pressure is generated in the belt hole 11a. Further, the control unit 5 activates the ink mist suction fan 71.

  In addition, the control unit 5 activates the blowing fan 62 and the suction fan 67. By the drive of the blowing fan 62, air is blown to the inkjet head 31 through the blowing hole 61a of the blowing chamber 61 and the ventilation hole 43a of the side plate 43 of the head holder 32. Further, by driving the suction fan 67, air is sucked from the head holder 32 through the suction hole 66a of the suction chamber 66 and the vent hole 45a of the side plate 45 of the head holder 32.

  Thereby, as shown in FIG. 6, the cooling air Wc is generated in the head holder 32. The cooling air Wc flows from the upstream side to the downstream side (left to right) in the transport direction of the sheet P. Here, part of the cooling air Wc leaks from the gap between the mounting opening 41 a and the inkjet head 31 to the space below.

  When the sheet P is fed from the sheet feeding unit (not shown) to the conveyance unit 2, the sheet P is conveyed while being held by suction by the conveyance belt 11. The control unit 5 causes the ink jet head 31 to eject ink on the sheet P conveyed below the head unit 21 to print an image. When the designated number of printed sheets is a plurality of sheets, the control unit 5 causes the ink jet head 31 to discharge the ink onto each sheet P which is sequentially fed and transported on the transport belt 11 to print an image.

  When the inkjet head 31 is driven, the inkjet head 31 generates heat. On the other hand, in the inkjet printing apparatus 1, the inkjet head 31 is cooled by the cooling air Wc, and the temperature rise is suppressed. Thus, the temperature of the inkjet head 31 can be suppressed to the rated temperature or less of the head driver IC.

  In the space between the head holder 32 and the conveyance belt 11, as shown in FIG. 7, a conveyance air flow Wt, a belt suction air flow Ws, and a cooling leakage air flow Wl are generated.

  The conveying air flow Wt is an air flow generated by the conveyance of the sheet by the conveying belt 11. The conveyance air flow Wt flows from the upstream side to the downstream side (left to right) in the conveyance direction of the sheet P.

  The belt suction air flow Ws is an air flow generated by the sheet suction fan 17 sucking air through the belt hole 11a.

  The cooling leakage air flow Wl is the cooling air Wc in the head holder 32 leaking from the gap between the mounting opening 41 a and the inkjet head 31. The cooling leakage air flow Wl flows in the same direction (left to right) as the cooling air Wc. That is, the cooling leak air flow Wl flows in the same direction as the transport air flow Wt.

  When the ink is ejected from the inkjet head 31, an ink mist M is generated. As shown in FIG. 7, the ink mist M flows from the upstream side to the downstream side (left to right) in the conveyance direction of the sheet P along the conveyance air flow Wt and the cooling leakage air flow Wl. At this time, a part of the ink mist M is collected by the sheet suction fan 17 through the belt hole 11 a by the belt suction air flow Ws. The ink mist which is not collected by the sheet suction fan 17 and is flowed to the downstream side of the conveyance unit 2 by the conveyance air flow Wt and the cooling leakage air flow Wl is collected by the ink mist collection unit 4.

  When the printed sheet P leaves the conveyance unit 2, the sheet P is conveyed to a discharge unit (not shown) and discharged. When the last sheet P is discharged, the control unit 5 stops the driving roller 12 and stops the sheet suction fan 17. In addition, the control unit 5 stops the blowing fan 62, the suction fan 67, and the ink mist suction fan 71. Thus, the printing operation is completed.

  As described above, in the inkjet printing apparatus 1, the cooling unit 22 generates the cooling air Wc flowing from the upstream side to the downstream side in the conveyance direction of the sheet P in the head holder 32. For this reason, the cooling leakage air flow Wl generated by the cooling air Wc leaking downward from the gap between the mounting opening 41 a and the inkjet head 31 flows in the conveyance direction of the sheet P. That is, the cooling leak air flow Wl flows in the same direction as the transport air flow Wt.

  Here, unlike the present embodiment, for example, when the cooling air in the head holder 32 flows in the front-rear direction, the cooling leak air flows in the front-rear direction. That is, the cooling leak air flow and the transport air flow Wt are orthogonal to each other. For this reason, the turbulent flow by collision of these airflows generate | occur | produces. This turbulent flow causes the ink mist to fly in various directions. The ink mist scattered in various directions adheres to various places in the apparatus and the paper P, and causes stains in the apparatus and stains of printed matter.

  On the other hand, in the inkjet printing apparatus 1 of the present embodiment, since the cooling leak air flow Wl and the transport air flow Wt flow in the same direction, the generation of turbulence due to the collision of the air flows can be suppressed. Therefore, the diffusion of the ink mist due to the turbulent flow can be suppressed. As a result, it is possible to reduce the contamination in the apparatus and the contamination of the printed matter.

  Further, in the ink jet printing apparatus 1, the ink mist collecting unit 4 is disposed on the downstream side of the transport unit 2. Then, the ink mist recovery unit 4 recovers the ink mist that has been guided to the downstream side of the transport unit 2 by the transport airflow Wt and the cooling leak airflow Wl. Thus, the ink mist can be efficiently collected without providing a mechanism such as a fan for guiding the ink mist.

  The control unit 5 preferably controls the blowing fan 62 and the suction fan 67 so that the blowing air from the blowing unit 51 is stronger than the suction air from the suction unit 52. As a result, the cooling leakage air flow Wl can be strengthened, and the ink mist can be more strongly guided along the sheet P conveyance direction. As a result, the collection efficiency of the ink mist can be improved.

  Further, the cooling unit 22 omits the blowing unit 51 or the suction unit 52, and the cooling air that flows from the upstream side to the downstream side in the conveyance direction of the sheet P by the one of the blowing unit 51 and the suction unit 52 is contained in the head holder 32. It may be configured to be generated.

  Moreover, in the above-mentioned embodiment, although the conveyance part 2 of the air suction system was shown, a paper conveyance mechanism is not restricted to this system. For example, an electrostatic adsorption method may be used.

  The present invention is not limited to the above embodiment as it is, and in the implementation stage, the constituent elements can be modified and embodied without departing from the scope of the invention. In addition, various inventions can be formed by appropriate combinations of a plurality of components disclosed in the above-described embodiment. For example, some components may be deleted from all the components shown in the embodiment.

DESCRIPTION OF SYMBOLS 1 inkjet printing apparatus 2 conveyance part 3 printing part 4 ink mist collection | recovery part 5 control part 11 conveyance belt 12 drive roller 13-15 driven roller 16 belt motor 17 sheet adsorption fan 21 head unit 22 cooling part 31 inkjet head 32 head holder 41 bottom plate 41a Mounting openings 42 to 45 Side plate 42a, 44a Ventilation holes 46 Top plate 51 Spraying part 52 Suction part 61 Spraying chamber 61a Spraying hole 62 Spraying fan 66 Suction chamber 66a Suction hole 67 Suction fan 71 Ink mist suction fan 72 Filter

Claims (4)

A transport unit for transporting the print medium;
An inkjet head which ejects ink onto a print medium transported by the transport unit;
A box head holder having a mounting opening to which the ink jet head is attached via a gap and holding the ink jet head;
A cooling unit configured to generate cooling air flowing from the upstream side to the downstream side in the transport direction of the printing medium in the head holder to cool the inkjet head;
The ink mist generated by the ink discharge by the ink jet head is guided to the downstream side of the conveyance unit by an air flow generated by the conveyance of the printing medium by the conveyance unit and an air flow in which the cooling air leaks from the gap. Inkjet printing device. The cooling unit is
A blowing unit that blows air to the ink jet head in the head holder from the upstream side of the head holder in the transport direction;
And a suction unit for sucking air from the head holder downstream of the head holder in the transport direction.
Blowing air generated by the spray unit, the inkjet printing device according to claim 1, wherein the stronger than the suction air generated by the suction unit. A transport unit for transporting the print medium;
An inkjet head which ejects ink onto a print medium transported by the transport unit;
A box head holder having a mounting opening to which the ink jet head is attached via a gap and holding the ink jet head;
A cooling unit configured to generate cooling air flowing from the upstream side to the downstream side in the transport direction of the printing medium in the head holder to cool the inkjet head;
The cooling unit is
A blowing unit that blows air to the ink jet head in the head holder from the upstream side of the head holder in the transport direction;
And a suction unit for sucking air from the head holder downstream of the head holder in the transport direction.
An ink jet printing apparatus characterized in that a blowing wind by the blowing unit is stronger than a suction wind by the suction unit. The ink jet printing apparatus according to claim 3 , further comprising an ink mist recovery unit disposed downstream of the transport unit in the transport direction and configured to recover ink mist.