CN211843680U - Printing device - Google Patents

Abstract

The utility model relates to a promote printing device of rotary drum's cooling effect. The printing device is provided with: a rotating drum that winds and rotates a recording medium around an outer peripheral surface of a cylindrical hollow outer peripheral member; a discharge head which faces the outer peripheral surface of the rotary drum and discharges a liquid to the recording medium wound around the outer peripheral surface of the rotary drum; and an air flow generating part that generates an air flow passing through a hollow portion surrounded by the outer peripheral member of the rotary drum, wherein the hollow portion of the rotary drum is provided with a rotary shaft and a plate-like support member that extends radially from the rotary shaft and supports the outer peripheral member, the rotary drum rotates in the rotational direction about the rotary shaft, the support member is provided with a through hole that penetrates the support member in the rotational direction, and a covering member that covers or fills the through hole, and the weight of the covering member is smaller than the weight calculated by the product of the volume of the through hole and the weight per unit volume of the support member.

Description

Printing device

Technical Field

The utility model relates to a printing device.

Background

Conventionally, there is known an image recording apparatus including a rotary drum, a discharge head, and an air flow generating unit for cooling the rotary drum by generating an air flow, as shown in patent document 1, for example. The rotary drum of the image recording apparatus has a support member that supports an outer peripheral member of the rotary drum, and a through hole that penetrates in a rotation direction of the rotary drum is formed in the support member.

However, when the airflow generated from the airflow generating unit passes through the rotary drum, a part of the airflow passes through the through-holes, and thus turbulence of the airflow occurs in the rotary drum. Thereby, the air flow may not smoothly pass through the rotary drum and the cooling effect of the rotary drum may be reduced. In addition, when the through-hole is not formed, it is difficult to reduce the weight of the rotary drum. Therefore, the image recording apparatus has a problem that it is difficult to achieve both weight reduction of the rotary drum and improvement of the cooling effect.

Patent document 1: japanese patent laid-open publication No. 2014-181082

SUMMERY OF THE UTILITY MODEL

The printing device of the application is provided with: a rotating drum that rotates while winding a recording medium around an outer peripheral surface of a hollow cylindrical outer peripheral member; a discharge head that faces the outer peripheral surface of the rotary drum and discharges a liquid onto the recording medium wound around the outer peripheral surface of the rotary drum; and an air flow generating unit that generates an air flow that passes through a hollow portion of the rotary drum surrounded by the outer peripheral member, wherein the hollow portion of the rotary drum is provided with a rotary shaft and a plate-like support member that extends radially from the rotary shaft and supports the outer peripheral member, the rotary drum rotates in a rotational direction about the rotary shaft, the support member is provided with a through hole that penetrates the support member in the rotational direction, and a covering member that covers or fills the through hole, and the covering member has a weight that is lighter than a weight calculated by a product of a volume of the through hole and a weight per unit volume of the support member.

Preferably, the covering member of the printing apparatus is a plate-shaped plate member and is fixed to a surface of the support member in a peripheral portion of the through-hole.

According to this configuration, the through-hole can be easily covered.

Preferably, in the printing apparatus, an end of the plate member has an inclined surface.

According to this configuration, the resistance to the airflow is reduced by the inclined surface of the plate member, and the turbulence of the airflow can be further reduced.

Preferably, the covering member of the printing apparatus is an embedding member that embeds the through-hole.

According to this structure, the through-hole is easily covered. This can reduce the air flow disturbance.

Preferably, in the printing apparatus, the thermal conductivity of the covering member is higher than the thermal conductivity of the support member.

According to this structure, the cooling effect of the rotary drum can be further improved.

Preferably, in the printing apparatus, a surface of the covering member is provided with heat radiating fins.

According to this structure, the cooling effect of the rotary drum can be further improved.

Drawings

Fig. 1 is a front view schematically showing the configuration of a printing apparatus according to a first embodiment.

Fig. 2 is a plan view schematically showing the configuration of the printing apparatus according to the first embodiment.

Fig. 3 is a front perspective view partially showing the configuration of the printing apparatus according to the first embodiment.

Fig. 4 is a rear perspective view partially showing the configuration of the printing apparatus according to the first embodiment.

Fig. 5 is a perspective view partially showing the structure of the rotary drum according to the first embodiment.

Fig. 6 is a perspective view partially showing the structure of the rotary drum according to the first embodiment, from which the covering member is omitted.

Fig. 7 is a partial sectional view schematically illustrating a cross section of the auxiliary heat dissipation member according to the first embodiment.

Fig. 8 is a partially enlarged view showing a detailed structure of the rotary drum according to the first embodiment.

Fig. 9 is a partial sectional view showing a detailed structure of the rotary drum according to the first embodiment.

Fig. 10 is a partially enlarged view showing a detailed structure of the rotary drum according to the second embodiment.

Fig. 11 is a partial sectional view showing a detailed structure of the rotary drum according to the second embodiment.

Fig. 12 is a partial sectional view showing a detailed structure of the rotary drum according to the third embodiment.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings described below, the dimensions of the respective members and the like are shown to be different from the actual dimensions so that the members and the like can be recognized.

1. First embodiment

Fig. 1 is a front view schematically illustrating the configuration of a printing apparatus 1. In fig. 1 and the following drawings, an XYZ rectangular coordinate system is illustrated.

In the printing apparatus 1, a unwinding section 2, a processing section 3, and a winding section 4 are arranged. The unwinding section 2, the processing section 3, and the winding section 4 are housed in a case member 10 serving as an exterior member. The unwinding section 2 and the winding section 4 have an unwinding shaft 20 and a winding shaft 40, respectively. Both ends of the sheet S as a recording medium are wound in a roll shape around the unwinding shaft 20 and the winding shaft 40, and are bridged therebetween. Then, the sheet S is conveyed from the unwinding shaft 20 to the processing portion 3 along the conveying path Pc, and after receiving the printing process performed by the processing unit 3U, is conveyed to the winding shaft 40. The types of sheets S are roughly classified into paper and film. Specific examples of the paper include fine paper, cast paper, coated paper, and the film includes synthetic paper, PET (Polyethylene terephthalate), PP (polypropylene), and the like. In the following description, one of both surfaces of the sheet S on which an image is recorded is referred to as a front surface, and the opposite surface is referred to as a back surface.

The unwinding section 2 includes an unwinding shaft 20 for winding one end of the sheet S and a driven roller 21 for winding the sheet S pulled out from the unwinding shaft 20. The unwinding shaft 20 winds and supports an end portion of the sheet S in a state where the surface of the sheet S faces outward. Then, by rotating the unwinding shaft 20 in the clockwise direction on the paper surface of fig. 1, the sheet S wound around the unwinding shaft 20 is unwound to the processing section 3 via the driven roller 21. The sheet S is wound around the unwinding shaft 20 through a core tube (not shown) that is detachable from the unwinding shaft 20. Therefore, when the sheet S of the unwinding shaft 20 is used up, a new core tube around which the rolled sheet S is wound is attached to the unwinding shaft 20, whereby the sheet S of the unwinding shaft 20 can be replaced.

The processing unit 3 is a member that supports the sheet S unwound from the unwinding unit 2 by the rotary cylinder 30, and prints an image on the sheet S by performing processing appropriately by the processing unit 3U disposed along the outer peripheral surface 301a of the rotary cylinder 30. In the processing unit 3, a front driving roller 31 and a rear driving roller 32 are provided on both sides of the rotary drum 30, and the sheet S conveyed from the front driving roller 31 to the rear driving roller 32 is subjected to image printing processing while being supported by the rotary drum 30.

The front drive roller 31 has a plurality of minute protrusions formed by thermal spraying on an outer circumferential surface thereof, and winds the sheet S unwound from the unwinding section 2 from a rear surface side. The front drive roller 31 rotates clockwise on the paper surface of fig. 1, and conveys the sheet S unwound from the unwinding unit 2 to the downstream side of the conveyance path Pc. Further, a pinch roller 31n is provided to the front drive roller 31. The pinch roller 31n is urged toward the front drive roller 31 and abuts against the surface of the sheet S, and sandwiches the sheet S between the pinch roller and the front drive roller 31. This ensures a frictional force between the front drive roller 31 and the sheet S, and enables the sheet S to be reliably conveyed by the front drive roller 31.

The rotary drum 30 is a cylindrical drum having a center line parallel to the Y axis. The rotary drum 30 has an outer peripheral member 301. A hollow portion 300 penetrating along the Y axis is formed in a portion defined by the outer peripheral member 301. Then, the sheet S is wound around the outer peripheral surface 301a of the outer peripheral member 301 surrounding the hollow portion 300. The rotary drum 30 has a rotary shaft 302 extending along the Y axis through the cylindrical center line in the hollow portion 300. The rotary shaft 302 is rotatably supported by a support mechanism, not shown, and the rotary drum 30 rotates about the rotary shaft 302.

The sheet S conveyed from the front driving roller 31 to the rear driving roller 32 is wound around the outer peripheral surface 301a of the rotary drum 30 from the back side. The rotary drum 30 is driven to rotate in the rotation direction Ds of the sheet S by the frictional force with the sheet S, and supports the sheet S from the back side. In the processing section 3, driven rollers 33, 34 that fold back the sheet S are provided at both sides of the winding section facing the rotary drum 30. Here, the driven roller 33 wraps the surface of the sheet S between the front driving roller 31 and the rotary drum 30 and folds the sheet S. On the other hand, the driven roller 34 wraps the surface of the sheet S between the rotary drum 30 and the rear driving roller 32 and folds back the sheet S. In this way, by folding the sheet S back at the upstream and downstream sides in the rotation direction Ds with respect to the rotary drum 30, the length of the portion of the sheet S wound around the rotary drum 30 can be ensured.

The rear driving roller 32 has a plurality of minute protrusions formed by thermal spraying on an outer circumferential surface thereof, and winds the sheet S conveyed from the rotary drum 30 via the driven roller 34 from the back side. The rear driving roller 32 rotates clockwise on the sheet of fig. 1, and conveys the sheet S to the winding section 4. Further, a pinch roller 32n is provided to the rear driving roller 32. The pinch roller 32n is urged toward the rear driving roller 32 and abuts against the surface of the sheet S, and sandwiches the sheet S between the pinch roller and the rear driving roller 32. This ensures a frictional force between the rear driving roller 32 and the sheet S, and the sheet S can be reliably conveyed by the rear driving roller 32.

The sheet S conveyed from the front driving roller 31 to the rear driving roller 32 is supported by the outer peripheral surface 301a of the rotary drum 30. The processing unit 3 is provided with a processing unit 3U for printing a color image on the surface of the sheet S supported by the rotary cylinder 30. The processing unit 3U has an arc-shaped unit support member 35 along the outer peripheral surface 301a of the rotary drum 30, and the printing heads 36a to 36e as discharge heads and the UV irradiators 37a and 37b are supported by the unit support member 35.

The four printing heads 36a to 36d arranged in order in the rotation direction Ds correspond to yellow, cyan, magenta, and black, and ink as liquid of the corresponding color is ejected from the nozzles by an ink jet method. The four print heads 36a to 36d are arranged radially from the rotation axis 302 of the rotary drum 30 and are arranged along the outer peripheral surface 301a of the rotary drum 30. The print heads 36a to 36d are positioned with respect to the rotary drum 30 by the unit support member 35, and face the rotary drum 30 with a slight gap from the outer peripheral surface 301 of the rotary drum 30. Thus, the print heads 36a to 36d face the surface of the sheet S wound around the rotary drum 30 with a predetermined platen gap. In a state where the platen gap is defined by the unit support member 35 in this way, the ink is ejected to a desired position on the surface of the sheet S by causing the print heads 36a to 36d to eject the ink, and a color image is formed on the surface of the sheet S. As the ink used in the printing heads 36a to 36d, uv (ultraviolet) ink which is cured by irradiation with ultraviolet rays is used. Therefore, in the process unit 3U, UV irradiators 37a, 37b are provided in order to cure and fix the ink on the sheet S. The ink curing is performed in two stages, i.e., a temporary curing stage and a main curing stage. A UV irradiator 37a for temporary curing is disposed between each of the four printing heads 36a to 36 d. That is, the UV irradiator 37a is a member that cures the ink to such an extent that the shape of the ink is not deformed by irradiating weak ultraviolet rays, and does not completely cure the ink. On the other hand, a UV irradiator 37b for main curing is provided on the downstream side of the four printing heads 36a to 36d in the rotation direction Ds. That is, the UV irradiator 37b is an irradiator that irradiates ultraviolet rays stronger than the UV irradiator 37a to completely cure the ink. In this way, the color images formed by the plurality of printing heads 36a to 36d can be fixed on the surface of the sheet S by the UV irradiators 37a and 37 b. A print head 36e is provided downstream of the UV irradiator 37b in the rotation direction Ds. The print head 36e ejects transparent UV ink from nozzles by an ink jet method. The print head 36e is positioned with respect to the rotary drum 30 by the unit support member 35, and faces the rotary drum 30 with a slight gap from the outer peripheral surface 301a of the rotary drum 30. Thus, the print head 36e faces the surface of the sheet S wound around the rotary drum 30 with a predetermined platen gap. In a state where the platen gap is defined by the unit support member 35 in this way, the ink is ejected onto a desired position on the surface of the sheet S by causing the print head 36e to eject the ink, and the color image on the surface of the sheet S is covered with the transparent ink.

In this manner, the printing heads 36a to 36e and the UV irradiators 37a and 37b are attached to the unit support member 35, thereby constituting the processing unit 3U. The unit support member 35 is supported along the X axis by two rails 351 extending along the Y axis, and is movable along the Y axis on the rails 351 in accordance with the print heads 36a to 36e and the UV irradiators 37a and 37 b. When printing is performed on the sheet S, the unit support member 35 is positioned at a printing position Ta (fig. 2) facing the rotary cylinder 30. On the other hand, when the worker performs maintenance on the printing heads 36a to 36e and the UV irradiators 37a and 37b, the unit support member 35 is positioned at a working position Tc (fig. 2) moved in the-Y direction. This enables the worker to perform maintenance on the printing heads 36a to 36e and the UV irradiators 37a, 37b at the working position Tc separated from the rotary drum 30. The approach of the worker to the working position Tc is performed to open an unillustrated opening/closing door provided at the-Y direction side of the case member 10.

Further, in the processing unit 3, a UV irradiator 38 is provided on the downstream side in the rotation direction Ds with respect to the print head 36 e. The UV irradiator 38 is a member that completely cures the transparent ink discharged from the print head 36e by irradiating strong ultraviolet rays. Thereby, the transparent ink covering the color image can be fixed on the surface of the sheet S.

The sheet S on which the color image is formed by the processing unit 3 is conveyed to the take-up unit 4 by the rear driving roller 32. The winding unit 4 includes a winding shaft 40 for winding one end of the sheet S, and a driven roller 41 for winding the sheet S from the back side between the winding shaft 40 and the rear driving roller 32. The take-up shaft 40 takes up and supports the end of the sheet S with the surface of the sheet S facing outward. That is, when the take-up shaft 40 rotates clockwise on the paper surface of fig. 1, the sheet S conveyed from the rear driving roller 32 is taken up by the take-up shaft 40 via the driven roller 41. The sheet S is wound around the winding shaft 40 via a core tube (not shown) that is detachable from the winding shaft 40. Therefore, when the sheet S wound around the winding shaft 40 is in the fully wound state, the sheet S can be removed together with the core tube.

The UV ink discharged from the print heads 36a to 36e is cured while generating heat by irradiation of ultraviolet rays. Therefore, heat from the UV ink is transmitted to the rotary cylinder 30 via the sheet S, thereby thermally expanding the rotary cylinder 30. As a result, the platen gap, which is the interval between the rotary drum 30 and the print heads 36a to 36e, may vary. In particular, in the printing apparatus 1 in which the UV irradiators 37a, 37b, and 38 irradiate the ultraviolet rays to the portion of the sheet S wound around the rotary cylinder 30 as shown in fig. 1, there is a case where the rotary cylinder 30 is heated by heat generation at the time of curing of the UV ink, and the platen gap fluctuates. Further, the rotary drum 30 may be heated by heat emitted from the UV irradiators 37a, 37b, 38 in addition to heat from the UV ink. Therefore, the printing apparatus 1 includes an airflow generating unit 6 that generates airflows Fa and Fb (fig. 2) that pass through the hollow portion 300 of the rotary cylinder 30 in order to cool the rotary cylinder 30.

Next, the structure of the airflow generating unit 6 will be described.

Fig. 2 is a plan view schematically illustrating the structure of the printing apparatus 1 shown in fig. 1. Fig. 3 is a front perspective view partially illustrating the configuration of the printing apparatus 1 shown in fig. 1. Fig. 4 is a rear perspective view partially illustrating the configuration of the printing apparatus 1 shown in fig. 1. In fig. 3 and 4, the internal structure of the printing apparatus 1 is shown with the upper portion of the housing member 10 removed, and the processing unit 3U, the sheet S, and the like are omitted.

As shown in fig. 2, inside the housing member 10 of the printing apparatus 1, a printing space Ra in which an image is formed on a sheet S, a flow path space Rb provided on the-Y direction side with respect to the printing space Ra, and a work space Rc provided on the-Y direction side of the flow path space Rb are provided. The airflow generating unit 6 generates the airflow Fa flowing in the-Y direction in the printing space Ra via the rotary cylinder 30, and discharges the flowing airflow Fa as the airflow Fb in the channel space Rb. Specifically, airflow generating unit 6 includes four blower fans 61 provided on the + Y direction side with respect to rotary drum 30, and six exhaust fans 62, 63 provided on the-Y direction side with respect to rotary drum 30.

The four blower fans 61 are disposed along the X axis below a horizontal virtual plane P30 including the rotation center line of the rotary drum 30. Each blower fan 61 is disposed to face the hollow portion 300 of the rotary drum 30. The housing member 10 is provided with ventilation windows 11 facing the hollow portion 300 from the + Y direction side, and each of the blower fans 61 blows air taken in from the outside of the printing apparatus 1 to the hollow portion 300 of the rotary cylinder 30 through the ventilation windows 11. Of the four air-sending fans 61, the two air-sending fans 61 at the center in the arrangement direction are arranged so as to be offset downward from the two air-sending fans 61 at the opposite ends. By arranging the four air blowing fans 61 according to the shape of the hollow portion 300, air can be efficiently blown into the hollow portion 300.

The six exhaust fans 62 and 63 are also disposed below a horizontal virtual plane P30 that includes the rotation center line of the rotary drum 30. These exhaust fans 62 and 63 discharge the air sucked from the hollow portion 300 of the rotary cylinder 30 to the outside of the printing apparatus 1 through the flow path space Rb. Four exhaust fans 62 out of the six exhaust fans 62, 63 are arranged at the boundary between the printing space Ra and the flow path space Rb in a state of facing the hollow portion 300 of the rotary cylinder 30. Therefore, each exhaust fan 62 discharges the air sucked from the hollow portion 300 along the Y-axis direction toward the flow path space Rb.

On the other hand, the two exhaust fans 63 are disposed so as to correspond to both ends of the hollow portion 300 in a state of being directed to both outer sides along the X axis orthogonal to the direction of the rotation shaft 302 of the rotary drum 30. Therefore, the exhaust fan 63 on the-X direction side ejects the air sucked from the hollow portion 300 and the air ejected from the exhaust fan 62 toward the-X direction side along the flow path space Rb. The exhaust fan 63 on the + X direction side ejects air taken in from the hollow portion 300 of the rotary drum 30 and air ejected from the exhaust fan 62 toward the + X direction side along the flow path space Rb. The casing member 10 is provided with ventilation windows 12 at both ends of the flow path space Rb in the + X direction and the-X direction, and air blown by the exhaust fans 63 is discharged to the outside of the printing apparatus 1 through the ventilation windows 12.

In this way, the airflow generation unit 6 having the blower fan 61 and the exhaust fans 62 and 63 is provided. Therefore, in the printing apparatus 1, an air flow Fa that causes air to flow into the flow path space Rb through the hollow portion 300 of the rotary cylinder 30 along the Y axis and an air flow Fb that causes air flowing into the flow path space Rb from the rotary cylinder 30 to be discharged along the X axis are generated. That is, the air sucked from the outside of the printing apparatus 1 moves from the + Y direction side to the-Y direction side along the airflow Fa, and then moves in the + X direction and the-X direction along the airflow Fb, and is discharged to the outside of the printing apparatus 1. At this time, since the exhaust fan 63 is disposed on the downstream side of the airflow Fa, the direction of the airflow from the airflow Fa to the airflow Fb is smoothly switched. In this way, exhaust fan 63 not only discharges air from hollow portion 300 of rotary drum 30, but also functions as an airflow switching fan that switches the direction of airflow Fa.

The printing apparatus 1 is provided with frame members 81, 82, and 83 arranged to separate the printing space Ra, the flow path space Rb, and the working space Rc. The frame members 81, 82, 83 have a substantially flat plate shape extending along the X axis, and are arranged in the order of the frame members 81, 82, 83 from the + Y direction side along the-Y direction side. The frame member 81 has four openings 811 facing the hollow 300 and aligned along the X axis. The frame member 81 holds the blower fan 61 fitted into each opening 811. The frame member 82 is disposed at the boundary between the printing space Ra and the flow path space Rb, and has four openings 821 facing the hollow portion 300 and arranged along the X axis. The frame member 82 holds the exhaust fans 62 fitted into the respective openings 821. Further, the frame member 82 partitions between the printing space Ra and the flow path space Rb. The frame member 83 is disposed at a boundary between the flow path space Rb and the work space Rc, and partitions the flow path space Rb and the work space Rc.

As described above, the unit support member 35 is movable along the Y axis along with the printing heads 36a to 36e and the UV irradiators 37a and 37b between the printing position Ta in the printing space Ra and the working position Tc in the working space Rc. In order to prevent interference with the unit support member 35 that moves along the Y axis, the frame members 82 and 83 are configured to be lower than the movement path of the unit support member 35 and the like. However, the frame member 83 is configured to be higher than the exhaust fans 62 and 63 so as to reliably block the airflows Fa and Fb between the spaces Rb and Rc. Specifically, the height of the frame members 82 and 83 is equal to the height of the virtual plane P30 of the rotary drum 30.

Next, the structure of the rotary drum 30 will be described.

Fig. 5 is a perspective view partially showing the structure of the rotary drum 30. Fig. 6 is a perspective view partially showing the structure of the rotary drum 30 from which the covering member 401 in fig. 5 is omitted.

As shown in fig. 5 and 6, the rotary drum 30 includes an outer peripheral member 301 surrounding a hollow portion 300 penetrating along the Y axis, and a rotary shaft 302 disposed in the hollow portion 300 and extending along the Y axis. As shown in fig. 5, the rotary drum 30 has a plurality of arms 303 as support members extending radially from the rotary shaft 302 in the hollow portion 300 and arranged at equal angles in the rotation direction Ds. The inner circumferential surface 301b of the outer circumferential member 301 is connected to the rotary shaft 302 via a plurality of arms 303. In this way, the outer peripheral member 301 is supported by the plurality of arms 303.

The arm 303 is configured in a flat plate shape that becomes thinner as it goes to the outside in the radial direction of the rotary drum 30, and has the same length as the outer circumferential member 301 in the Y axis. A through hole 303a penetrating in the rotation direction Ds is formed in the arm 303. The through hole 303a has an elongated long hole shape along the Y axis. In the present embodiment, a plurality of through-holes 303a are provided in the arm 303 in the Y axis direction and the radial direction, respectively.

The through-hole 303a is a member for reducing the weight of the rotary drum 30. The rotary drum 30 is rotatable about the rotary shaft 302 in accordance with conveyance of the sheet S by driving of the front drive roller 31 and the rear drive roller 32. Therefore, in order to suppress the slip between the sheet S and the outer peripheral surface 301a of the rotary cylinder 30 at the start of the printing process and at the stop of the printing process, it is necessary to minimize the moment of inertia of the rotary cylinder 30. Therefore, the weight of the rotary drum 30 is reduced by forming the plurality of through holes 303a, thereby achieving weight reduction and minimizing the moment of inertia of the rotary drum 30.

Further, the rotary drum 30 has an auxiliary heat radiating member 304 formed on the inner peripheral surface 301b of the outer peripheral member 301. The auxiliary heat dissipation members 304 have an annular shape that surrounds the inner peripheral surface 301b of the outer peripheral member 301 once in the rotation direction Ds, and are provided in plurality at equal intervals along the Y axis. As shown in fig. 7, the auxiliary heat radiating member 304 has a convex shape toward the rotation shaft 302. Here, fig. 7 is a partial sectional view schematically illustrating a cross section of the auxiliary heat dissipation member 304. As shown in fig. 7, each of the plurality of auxiliary heat dissipation members 304 is formed to protrude from the inner circumferential surface 301b of the outer circumferential member 301, and has the same thickness T304 from the inner circumferential surface 301 b. Each auxiliary heat dissipation member 304 has a trapezoidal shape in cross section on the Y axis that narrows as it is radially separated from the inner peripheral surface 301 b. That is, the auxiliary heat dissipation member 304 has a wall surface 304a inclined in the direction of the airflow Fa at the upstream side of the airflow Fa passing through the hollow portion 300. In such a configuration, the air flow Fa can be reliably brought into contact with the auxiliary heat dissipation member 304 provided in the outer peripheral member 301, so that the outer peripheral member 301 can exchange heat with a large amount of rapid air flow Fa through the auxiliary heat dissipation member 304, and thus the outer peripheral member 301 can be efficiently cooled. The auxiliary heat dissipation member 304 also functions as a reinforcing member for maintaining the shape of the outer peripheral member 301.

The airflow Fa generated by the airflow generation unit 6 passes through the hollow portion 300 of the rotary drum 30 having the structure shown in fig. 5 to 7. As a result, heat exchange is performed between the airflow Fa and the rotary drum 30, so that the rotary drum 30 is cooled, and the variation in the platen gap is suppressed. In this way, the position of ink landing on the sheet S can be stabilized, and a good image can be formed.

As described above, in this embodiment, the rotary drum 30 winds the sheet S around the outer peripheral surface 301a of the hollow outer peripheral member 301 formed in a cylindrical shape. Then, the printing heads 36a to 36e eject ink onto the sheet S wound around the outer peripheral surface 301a of the rotary drum 30, thereby recording an image on the sheet S. Further, an airflow generating part 6 that generates an airflow Fa passing through the hollow part 300 of the rotary drum 30 is provided, so that the rotary drum 30 is cooled by the generated airflow Fa.

Here, a problem concerning cooling of the rotary drum 30 will be described. As described above, the through-hole 303a contributes to weight reduction of the rotary drum 30. However, when the air flow Fa generated by the blower fan 61 with respect to the rotary drum 30 passes through the hollow portion 300, a part of the air flow Fa passes through the through-holes 303a, and thus turbulence of the air flow Fa occurs in the rotary drum 30. Thus, the air flow Fa cannot smoothly pass through the rotary drum 30. Therefore, the problem that the cooling effect of the rotary drum 30 is reduced is clarified.

Therefore, in the present embodiment, as shown in fig. 5, a covering member 401 that covers the through-hole 303a formed in the rotary drum 30 is provided. Hereinafter, a specific configuration will be described.

Fig. 8 is a partially enlarged view showing a detailed structure of the rotary drum 30, and fig. 9 is a partially cross-sectional view showing a detailed structure of the rotary drum 30.

As shown in fig. 5 and 8, the rotary drum 30 includes a covering member 401 that covers the through-hole 303a formed in the arm 303. The covering member 401 is a member that covers the entire through-hole 303a in a plan view. The covering member 401 of the present embodiment is a thin plate-like plate member. The material of the covering member 401 is, for example, pet (polyethylene terephthalate). The thickness of the covering member 401 is, for example, about 0.1mm to 5 mm. The covering member 401 of the present embodiment is formed in a rectangular shape in a plan view.

The covering member 401 is fixed to one side 310 of the arm 303 at the peripheral portion of the through-hole 303 a. The cover member 401 is fixed to the one side 310 of the arm 303 with an adhesive, an adhesive tape, or the like. In the present embodiment, a plurality of through-holes 303a are formed in one arm 303, and the plurality of through-holes 303a are covered with one covering member 401. This enables the plurality of through holes 303a to be efficiently covered.

As shown in fig. 8 and 9, the end of the plate member serving as the covering member 401 has an inclined surface 401 a. Although the inclined surface 401a is provided at the entire end of the covering member 401 in the present embodiment, the inclined surface 401a may be provided only at the end in the + Y direction of the covering member 401 in a plan view. The inclined surface 401a reduces the resistance against the airflow Fa, thereby further reducing the turbulence of the airflow.

The weight of the covering member 401 is smaller than the weight calculated by multiplying the volume of the through-hole 303a by the weight per unit volume of the arm 303.

Here, the volume of the through-hole 303a is calculated by the product of the opening area of the through-hole 303a and the thickness of the through-hole 303a, that is, the thickness dimension of the arm 303 corresponding to the through-hole 303a in a plan view. Then, the product of the calculated volume of the through-hole 303a and the weight per unit volume of the arm 303 is obtained. In the present embodiment, the rotary drum 30 including the arm 303 is formed of aluminum. Therefore, the product of the calculated volume of the through-hole 303a and the weight per unit volume of aluminum can be obtained. When the extracted weight is set to the corresponding weight of the through-hole 303a, the weight of the covering member 401 is lighter than the corresponding weight of the through-hole 303 a. Therefore, the rotary drum 30 can be reduced in weight even when the through-hole 303a is covered with the covering member 401.

In the present embodiment, four through holes 303a are formed in one arm 303. In this case, the corresponding weight of the four through-holes 303a is compared with the weight of one covering member 401 covering the four through-holes 303 a. In the case where four covering members 401 are provided corresponding to the through holes 303a, the total weight of the four covering members 401 may be compared.

As described above, according to the above embodiment, the following effects can be obtained.

The arm 303 constituting the rotary drum 30 is provided with a through hole 303 a. The through-hole 303a is formed to reduce the weight of the rotary drum 30.

The through-hole 303a is covered with a plate-shaped covering member 401. Here, the weight of the covering member 401 is smaller than the weight calculated by the product of the volume of the through-hole 303a and the weight per unit volume of the arm 303. That is, the through-hole 303a is covered with a covering member 401 made of a light material. Therefore, since the through-holes 303a can be covered to smoothly pass the generated air flow Fa through the hollow portion 300 while achieving the weight reduction of the rotary drum 30, the turbulence of the air flow Fa is prevented, and the cooling effect of the rotary drum 30 can be enhanced.

Further, since the covering member 401 is a thin plate member, the through-hole 303a can be easily covered.

2. Second embodiment

Next, a second embodiment will be explained.

In the present embodiment, the configuration of the rotary drum 30A will be mainly described. Since the configuration other than the rotary drum 30A is the same as that of the first embodiment, the description thereof is omitted.

Fig. 10 is a partially enlarged view showing a detailed structure of the rotary drum 30A, and fig. 11 is a partially cross-sectional view showing a detailed structure of the rotary drum 30A.

As shown in fig. 10 and 11, the rotary drum 30A has a rotary shaft 302 and an arm 303. Further, the arm 303 is provided with a through hole 303 a. The configurations of the rotary shaft 302, the arm 303, the through-hole 303a, and the like are the same as those of the first embodiment, and therefore, the description thereof is omitted.

The rotary drum 30A has a covering member 402 covering the through-hole 303 a.

The covering member 402 of the present embodiment is an embedding member that embeds the through-hole 303 a. For example, the covering member 402 is a continuous foam formed by foam molding using foamed polyurethane as a raw material.

The shape of the covering member 402 in plan view is the same as the shape of the opening portion of the through-hole 303a in plan view, and is almost the same size. The covering member 402 is embedded in the entire opening portion of the through-hole 303a in a plan view. Thereby, the entire through-hole 303a is filled with the covering member 402. As shown in fig. 11, the thickness of the covering member 402 of the present embodiment is almost the same as the thickness of the arm 303 along the Z axis. This reduces the resistance against the airflow Fa, and can reduce the turbulence of the airflow Fa.

In the present embodiment, a plurality of through holes 303a are formed in one arm 303. One covering member 402 is embedded in one through-hole 303 a.

Further, the weight of the covering member 402 is lighter than the weight calculated by the product of the volume of the through-hole 303a and the weight per unit volume of the arm 303. Note that the volume of the through-hole 303a and the method of calculating the weight calculated by the product of the volume of the through-hole 303a and the weight per unit volume of the arm 303 are the same as those in the first embodiment, and therefore, the description thereof is omitted. As described above, the covering member in the present invention is not limited to the form of covering the through-hole 303a, but includes the form of filling the through-hole 303 a.

As described above, according to the above embodiment, the following effects can be obtained.

The through-hole 303a is filled with a light cover member 402 made of foamed polyurethane. Therefore, since the through-holes 303a are filled with the covering member 402 to smoothly pass the airflow Fa through the hollow portion 300 while reducing the weight of the rotary drum 30, turbulence of the airflow Fa is prevented, and the cooling effect of the rotary drum 30 can be improved.

3. Third embodiment

Next, a third embodiment will be explained.

In the present embodiment, the configuration of the rotary drum 30B will be mainly described. The configuration other than the rotary drum 30B is the same as that of the first embodiment, and therefore, the description thereof is omitted.

Fig. 12 is a partial sectional view showing a detailed configuration of the rotary drum 30B.

As shown in fig. 12, the rotary drum 30B has a rotary shaft 302 and an arm 303. Further, the arm 303 is provided with a through hole 303 a. The configurations of the rotary shaft 302, the arm 303, the through-hole 303a, and the like are the same as those of the first embodiment, and therefore, the description thereof is omitted.

The rotary drum 30B has a covering member 403 that covers the through-hole 303 a.

The covering member 403 covers the entire through-hole 303a in a plan view. The covering member 403 of the present embodiment is a thin plate-like plate member. Here, the thermal conductivity of the covering member 403 is higher than that of the arm 303. In the present embodiment, the arm 303 is formed of aluminum. Therefore, the covering member 403 is made of copper, for example, as a material having higher thermal conductivity than aluminum. This can improve the cooling effect of the rotary drum 30. The thickness of the covering member 403 is, for example, about 0.1mm to 5 mm. The covering member 403 of the present embodiment has a rectangular shape in plan view.

The covering member 403 is fixed to one side 310 of the arm 303 at the peripheral portion of the through-hole 303 a. The covering member 403 is fixed to the one side 310 of the arm 303 by, for example, an adhesive or an adhesive tape having high thermal conductivity. In the present embodiment, a plurality of through-holes 303a are formed in one arm 303, and the plurality of through-holes 303a are covered with one covering member 403. This enables the plurality of through holes 303a to be efficiently covered.

As shown in fig. 12, heat radiating fins 403a are provided on the surface of the covering member 403. In the present embodiment, a plurality of rod-shaped heat radiating fins 403a are arranged on the surface of the covering member 403. The form of the heat dissipating fins 403a is appropriately considered and arranged to such an extent that the airflow Fa is not disturbed.

Further, the weight of the covering member 403 including the heat radiating fins 403a is lighter than the weight calculated by the product of the volume of the through-hole 303a and the weight per unit volume of the arm 303. Note that the volume of the through-hole 303a and the method of calculating the weight calculated by the product of the volume of the through-hole 303a and the weight per unit volume of the arm 303 are the same as those in the first embodiment, and therefore, the description thereof is omitted.

In the present embodiment, four through holes 303a are formed in one arm 303. In this case, the corresponding weight of the four through-holes 303a is compared with the weight of one covering member 403 covering the four through-holes 303 a. In the case where four covering members 403 are provided corresponding to the through holes 303a, the total weight of the four covering members 403 may be compared.

As described above, according to the above embodiment, the following effects can be obtained.

The through-hole 303a is covered with a covering member 403 having high thermal conductivity. Therefore, the through-hole 303a can be covered with the covering member 403 while reducing the weight of the rotary drum 30, thereby further improving the cooling effect of the rotary drum 30.

4. Modification examples

The present invention is not limited to the above-described embodiments, and various modifications, improvements, and the like may be added to the above-described embodiments. Hereinafter, modifications will be described.

Modification example 1

In the first and third embodiments, the covering members 401 and 403 are disposed on the one surface 310 of the arm 303, but the present invention is not limited to this configuration. For example, the covering members 401 and 403 may be disposed on the surface of the arm 303 opposite to the first surface 310. The covering members 401 and 403 may be disposed on both the one surface 310 and the surface opposite to the one surface 310 of the arm 303. In addition, when the covering members 401 and 403 are disposed on both surfaces of the arm 303, the weight of the two covering members 401 and 403 is made lighter than the corresponding weight of the through-hole 303 a. Even in this manner, since the through-holes 303a are covered, the cooling effect can be improved while achieving a reduction in weight of the rotary drum 30.

Modification 2

In the first embodiment, the covering member 401 is a plate member, but is not limited thereto. For example, a thin film member or a thin sheet member may be used. Even in this manner, the through-hole 303a can be covered, and the same effects as described above can be obtained.

Modification example 3

In the second embodiment, the covering member 402 as the embedding member is a continuous bubble body, but the present invention is not limited to this configuration. For example, the embedded member may be a plate member. The plate member may be a resin material or the like, or may be a metal member. Even in this manner, the same effects as described above can be obtained.

Modification example 4

The shape, number, arrangement, and the like of the arms 303 can be appropriately changed. The shape, number, arrangement, and the like of the through-holes 303a provided in the arm 303 can be appropriately changed.

Modification example 5

The shape, number, arrangement, and the like of the auxiliary heat dissipation members 304 provided on the rotary drum 30 can be appropriately changed. The auxiliary heat dissipation member 304 may be omitted.

Modification example 6

The airflow generating unit 6 can be variously modified. Therefore, the number and arrangement of the blower fans 61 and the exhaust fans 62 and 63 can be changed as appropriate.

Hereinafter, the contents derived from the embodiments will be described.

The printing device is provided with: a rotating drum that rotates while winding a recording medium around an outer peripheral surface of a hollow cylindrical outer peripheral member; a discharge head that faces the outer peripheral surface of the rotary drum and discharges a liquid onto the recording medium wound around the outer peripheral surface of the rotary drum; and an air flow generating unit that generates an air flow that passes through a hollow portion of the rotary drum surrounded by the outer peripheral member, wherein the hollow portion of the rotary drum is provided with a rotary shaft and a plate-shaped support member that extends radially from the rotary shaft and supports the outer peripheral member, the rotary drum rotates in a rotational direction about the rotary shaft, the support member is provided with a through hole that penetrates the support member in the rotational direction, and a covering member that covers or fills the through hole, and the covering member has a weight that is lighter than a weight calculated by a product of a volume of the through hole and a weight per unit volume of the support member.

According to this configuration, the through-hole is provided in the support member constituting the rotary drum. The through-hole is formed to reduce the weight of the rotary drum.

In addition, the through-holes disturb the airflow generated by the airflow generating portion, thereby reducing the cooling effect of the rotary drum.

Therefore, the through-hole is covered or filled with the covering member. Here, the weight of the covering member is lighter than the weight calculated by the product of the volume of the through-hole and the weight per unit volume of the support member. That is, the through-hole is covered or buried by a covering member made of a light material. Therefore, the through holes are covered to prevent the turbulence of the air flow while achieving the reduction in weight of the rotary drum, so that the air flow can smoothly pass through the rotary drum. This can improve the cooling effect of the rotary drum.

Description of the symbols

1 … printing device; 6 … airflow generating part; 10 … shell member; 30. 30A, 30B … rotating the drum; 36a, 36b, 36c, 36d, 36e …; 37a, 37b, 38 … UV illuminator; 61 … blower fan; 62. 63 … exhaust fan; 81. 82, 83 … frame members; 300 … hollow portion; 301 … outer peripheral components; 301a … outer circumferential surface; 301b … inner peripheral surface; 302 … rotating the shaft; 303 … arms; 303a … through the hole; 304 … auxiliary heat dissipation members; 304a … wall; 310 … in one aspect; 401. 402, 403 … covering component; 401a … inclined plane; 403a … heat sink fins.

Claims (6)

1. A printing apparatus is characterized by comprising:

a rotating drum that rotates while winding a recording medium around an outer peripheral surface of a hollow cylindrical outer peripheral member;

a discharge head that faces the outer peripheral surface of the rotary drum and discharges a liquid onto the recording medium wound around the outer peripheral surface of the rotary drum;

an air flow generating section that generates an air flow passing through a hollow portion surrounded by the outer peripheral member of the rotary drum,

a rotating shaft and a plate-like support member extending radially from the rotating shaft and supporting the outer peripheral member are provided in the hollow portion of the rotating drum, the rotating drum rotates in a rotating direction about the rotating shaft,

the support member is provided with a through hole penetrating the support member in the rotational direction, and a covering member covering or filling the through hole,

the weight of the covering member is lighter than the weight calculated by multiplying the volume of the through-hole by the weight per unit volume of the support member.

2. Printing device according to claim 1,

the covering member is a plate-like plate member and is fixed to a surface of the support member at a peripheral portion of the through-hole.

3. Printing device according to claim 2,

the end of the plate member has an inclined surface.

4. Printing device according to claim 1,

the covering member is an embedding member that embeds the through-hole.

5. Printing device according to claim 1,

the thermal conductivity of the covering member is higher than that of the support member.

6. Printing device according to claim 5,

the surface of the covering member is provided with heat radiating fins.

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