JP2013028016A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image forming apparatus which can suppress occurrence of a wrinkle on a recording medium conveyed while being supported on a conveying surface even if the recording medium is wavy.SOLUTION: A sheet member P conveyed by an image recording drum 36 is sucked by a suction hole formed on a guide surface 82A at a position being just before it is pressed against the conveying surface 100A by a pressing roll 70. As a result, tension (back tension) acts on the sheet member P pressed against the conveying surface 100A. Since the sheet member P to which the tension is applied is pressed against the conveying surface 100A by the pressing roll 70 successively from the leading edge of the sheet member P, occurrence of a wrinkle on the sheet member P conveyed while being supported on the conveying surface 100A is suppressed even if the recording member P is wavy.

Description

  The present invention relates to an image forming apparatus that forms an image on a recording medium.

  Patent Document 1 describes an ink jet recording apparatus that employs a drum conveyance method. In this ink jet recording apparatus, in order to prevent the recording medium wound around the conveyance surface of the drawing drum (image recording drum) from being wrinkled, the recording medium is sucked and tension (back tension) is applied to the recording medium. Is provided. This suction pump (suction means) is disposed upstream of the drawing drum in the conveyance direction of the recording medium.

JP 2009-220954 A

  However, in the conventional configuration, when the recording medium is undulating, the rear end side of the recording medium that has moved away from the suction means and moved to the image recording drum sticks to the image recording drum earlier than the front end side of the recording medium. Sometimes. This may cause wrinkles on the recording medium.

  An object of the present invention is to suppress wrinkling of a recording medium even when the recording medium is wavy.

  An image forming apparatus according to a first aspect of the present invention includes an image recording drum that supports and conveys a sheet-like recording medium on a conveying surface while rotating, and a pressing member that presses the recording medium against the conveying surface of the image recording drum. A suction means that is provided upstream of the pressing member in the recording medium conveyance direction and sucks the recording medium to apply tension to the recording medium; and a rear end side of the recording medium sucked by the suction means. A blowing unit that moves in a direction away from the conveying surface by sending air; and an image on a recording medium that is arranged to face the conveying surface of the image recording drum and is pressed against the conveying surface by the pressing member. And image forming means for forming the image.

  According to the above configuration, the suction unit sucks the recording medium and applies tension (back tension) to the recording medium. Further, the blowing unit moves the rear end side of the recording medium sucked by the suction unit in a direction away from the conveying surface by sending wind.

  Thus, the suction is applied to the rear end side of the recording medium, whereby tension is applied to the vicinity of the rear end of the recording medium. Then, the recording medium is grounded and pressed against the conveyance surface in order from the leading end of the recording medium. For this reason, even when the recording medium is wavy, the occurrence of wrinkles on the recording medium can be suppressed.

  The image forming apparatus according to a second aspect of the present invention is the image forming apparatus according to the first aspect, wherein the blower unit is disposed between the suction unit and the conveyance surface from the upstream side in the recording medium conveyance direction with respect to the suction unit. It is characterized by sending wind to

  According to the above configuration, since the blowing unit sends air between the suction unit and the conveyance surface from the upstream side in the conveyance direction of the recording medium with respect to the suction unit, the conveyance unit effectively conveys the rear end side of the recording medium. It can be moved away from the surface.

  An image forming apparatus according to a third aspect of the present invention is the image forming apparatus according to the first aspect, wherein the blowing unit sends air between the suction unit and the transport surface from the inside of the image forming drum. To do.

  According to the above configuration, since the blowing unit sends air between the suction unit and the conveyance surface from the inside of the image forming drum, the rear end side of the recording medium is effectively moved away from the conveyance surface. Can do.

  The image forming apparatus according to a fourth aspect of the present invention is the image forming apparatus according to the second aspect, wherein the air blowing unit is upstream of the suction unit in the recording medium conveyance direction and outside the image forming drum. It is the ventilation member arrange | positioned, It is characterized by the above-mentioned.

  According to the above configuration, the air blowing member is disposed upstream of the suction unit in the recording medium conveyance direction and outside the image forming drum. Therefore, the sending member can be easily disposed.

  An image forming apparatus according to a fifth aspect of the present invention is the conveying drum according to the fourth aspect, wherein the conveying drum delivers the recording medium to the image forming drum upstream of the image forming drum in the conveying direction of the recording medium. And the air blowing member is provided inside the transport drum.

  According to the said structure, since the ventilation member is provided in the inside of a conveyance drum, it can suppress that the whole apparatus becomes large.

  An image forming apparatus according to a sixth aspect of the present invention is the image forming apparatus according to the fifth aspect, wherein a plurality of the blowing members are provided along a width direction of the recording medium to be conveyed.

  According to the above configuration, since the plurality of air blowing members are provided along the width direction of the recording medium to be conveyed, the air blowing member is arranged between the suction unit and the conveying surface across the width direction of the recording medium. Can be sent in.

  An image forming apparatus according to a seventh aspect of the present invention is the image forming apparatus according to any one of the fourth to sixth aspects, further comprising an operation control unit that controls the operation of the air blowing member, and the operation control unit is conveyed. The air blowing member is operated after a rear end portion of the recording medium passes through a position facing the air blowing member.

  According to the above configuration, the operation control unit operates the air blowing member after the rear end portion of the recording medium to be conveyed has passed the position facing the air blowing member. It is possible to suppress the side from being grounded (contacted) with the conveyance surface.

  An image forming apparatus according to an eighth aspect of the present invention is the image forming apparatus according to the seventh aspect, wherein the operation control unit is configured such that when the size of the recording medium is small, the recording medium is larger than when the size of the recording medium is large. The operation of the air blowing member arranged outside in the width direction is stopped.

  According to the above configuration, the operation control unit stops the operation of the air blowing member disposed outside the recording medium in the width direction when the size of the recording medium is small compared to when the size of the recording medium is large. Therefore, useless power can be reduced.

  An image forming apparatus according to a ninth aspect of the present invention is the image forming apparatus according to the first or second aspect, wherein the air is sucked through the through-hole formed in the conveying surface and is pressed against the conveying surface by the pressing member. An adsorbing device that adsorbs the recording medium to the transport surface, and a discharge device that discharges the air sucked by the adsorbing device to a place different from the place where the recording medium is adsorbed, are provided, It is a guide member that guides wind generated by the flow of air discharged by the discharge device between the suction means and the transport surface.

  According to the above configuration, since the guide member guides the wind generated by the flow of the air discharged by the discharge device between the suction unit and the transport surface, it is not necessary to provide a dedicated member for generating the wind.

  An image forming apparatus according to a tenth aspect of the present invention is the image forming apparatus according to the ninth aspect, wherein the guide member receives wind generated by a flow of air discharged by the discharge device through the conveyance surface, along the conveyance surface. It is characterized by guiding the wind.

  According to the said structure, a guide member receives the wind produced | generated by the flow of the air discharged | emitted by the discharge apparatus through the conveyance surface, and guides a wind along a conveyance surface. In this way, wind can be effectively sent between the suction means and the transport surface.

  An image forming apparatus according to an eleventh aspect of the present invention is the image forming apparatus according to the tenth aspect, wherein the guide member is formed by bending a plate member.

  According to the above configuration, the guide member can be easily formed by curving the plate member.

  An image forming apparatus according to a twelfth aspect of the present invention is the image forming apparatus according to the eleventh aspect, wherein the guide member is provided across the width direction of the recording medium to be conveyed.

  According to the above configuration, the guide member provided across the width direction of the recording medium to be conveyed can guide the wind between the suction unit and the conveyance surface across the width direction of the recording medium.

  An image forming apparatus according to a thirteenth aspect of the present invention is the image forming apparatus according to any one of the first to twelfth aspects, wherein the recording medium is a recording sheet, and the blowing unit and the conveying surface are separated by the blowing unit. An air volume control unit for controlling the air volume sent in between is provided, and the air volume control unit is compared with the case where the weight per unit area of the recording paper is light compared to the case where the weight per unit area of the recording paper is light. Then, the air volume generated by the blowing means is increased.

  According to the above configuration, the air volume control unit changes the air volume based on the weight (basis weight) per unit area of the recording paper. For this reason, the air blowing means can effectively move the rear end side of the recording medium in a direction away from the conveying surface.

  An image forming apparatus according to a fourteenth aspect of the present invention is the air volume control according to any one of the first to twelfth aspects, wherein the air volume is controlled between the suction unit and the conveying surface by the blowing unit. The air volume control unit increases the air volume generated by the blowing unit when the size of the recording medium is large compared to when the size of the recording medium is small.

  According to the above configuration, the air volume control unit changes the air volume based on the size of the recording medium. For this reason, the air blowing means can effectively move the rear end side of the recording medium in a direction away from the conveying surface.

  An image forming apparatus according to a fifteenth aspect of the present invention is the airflow control according to any one of the first to twelfth aspects, wherein the airflow control unit controls an airflow sent between the suction unit and the transport surface by the blowing unit. And the air volume control unit makes the air volume generated outside the width direction of the recording medium larger than the air volume generated inside the width direction of the recording medium.

  According to the above configuration, the air volume control unit increases the air volume generated outside in the width direction of the recording medium than the air volume generated inside in the width direction of the recording medium. For this reason, when the corner of the trailing edge of the recording medium is wavy (curled), the trailing edge of the recording medium can be effectively moved away from the conveying surface.

  According to the present invention, it is possible to suppress wrinkling of the recording medium even when the recording medium is wavy.

1 is a front view showing an image recording unit and the like employed in an image forming apparatus according to a first embodiment of the present invention. (A) (B) (C) It is the operation | movement figure which showed operation | movement of the conveyance drum and image recording drum which were employ | adopted as the image forming apparatus which concerns on 1st Embodiment of this invention from the front. FIG. 2 is a perspective view illustrating a transport drum, an image recording drum, and the like employed in the image forming apparatus according to the first embodiment of the present invention. 1 is a perspective view showing a paper guide of a tension applying device employed in an image forming apparatus according to a first embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention. FIG. 6 is a front view showing an image recording unit and the like employed in an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a front view showing an image recording unit and the like employed in an image forming apparatus according to a third embodiment of the present invention.

  An example of the image forming apparatus 10 according to the first embodiment of the present invention will be described with reference to FIGS. In addition, arrow UP in a figure shows the perpendicular direction upper direction.

(overall structure)
As shown in FIG. 5, the image forming apparatus 10 includes a sheet feeding unit 12 that supplies a sheet member P as a recording medium to the apparatus main body 10 </ b> A, and a processing liquid application that applies a processing liquid to the image forming surface of the sheet member P. A portion 14, an image recording portion 16 that forms an image on the sheet member P, a drying portion 18 that reduces (drys) the moisture of the sheet member P in order to enhance the film quality of the drawing portion on which the image is formed, and formation The image forming apparatus includes a fixing unit 20 that fixes the formed image on the sheet member P, and a discharge unit 22 that discharges the sheet member P.

  In the paper feeding unit 12, the sheet members P are stacked, and the stacked sheet members P are sent one by one toward the apparatus main body 10A. Further, on the downstream side in the conveyance direction of the sheet member P (hereinafter simply referred to as the conveyance direction) with respect to the sheet feeding unit 12, the sheet member P fed from the sheet feeding unit 12 is guided toward the apparatus main body 10A. A paper tray 24 is provided. Further, on the downstream side of the sheet feeding tray 24, a sheet feeding drum 26 is provided in the apparatus main body 10A to convey the sheet member P along the outer peripheral surface while rotating. Then, the sheet member P is conveyed to the processing liquid application unit 14 by the paper supply drum 26.

  Further, the treatment liquid application unit 14 is provided with a treatment liquid application drum 28 that receives the sheet member P conveyed by the paper supply unit 12 while rotating and conveys the sheet member P along the outer peripheral surface. Specifically, a holding member 30 that holds the front end portion of the sheet member P is provided on the outer peripheral surface of the treatment liquid coating drum 28.

  With this configuration, with the leading end of the sheet member P held by the holding member 30, the sheet member P moves downstream along the outer peripheral surface of the treatment liquid application drum 28 in the conveyance direction by the rotation of the treatment liquid application drum 28. It is designed to be transported.

  Note that the holding member 30 is also provided in a transport drum 34, an image recording drum 36, a transport drum 40, a drying drum 42, a transport drum 48, and a fixing drum 50, which will be described later.

  Further, a processing liquid coating device 32 that coats the processing liquid on the image forming surface of the sheet member P conveyed along the outer peripheral surface of the processing liquid coating drum 28 is provided above the processing liquid coating drum 28 in the vertical direction. It has been. The treatment liquid has an effect of accelerating separation of the color material (pigment) and the solvent by reacting with droplets described later to aggregate the color material (pigment).

  Further, downstream of the processing liquid coating drum 28 in the transport direction, the sheet member P transported by the processing liquid coating drum 28 is received by the holding member 30 while being rotated, and transported toward the image recording unit 16. A drum 34 is provided.

  Further, the image recording unit 16 receives the sheet member P conveyed by the conveyance drum 34 by the holding member 30 while rotating and conveys the sheet member P along an outer peripheral surface (a conveyance surface 100A described later) as an example of a conveyance member. An image recording drum 36 is provided. Further, above the image recording drum 36 in the vertical direction, liquid droplets such as ink are ejected onto the sheet member P conveyed along the outer peripheral surface of the image recording drum 36 to form an image on the image forming surface of the sheet member P. A droplet discharge head 38 is provided as an example of image forming means to be formed.

  The droplet discharge head 38 is provided so as to extend in the width direction of the sheet member P to be conveyed, has an ink discharge range corresponding to the maximum width of the sheet member P, and is a so-called full line head. In the present embodiment, as an example, four color droplet discharge heads 38 of basic colors Y (yellow), M (magenta), C (cyan), and K (black) are arranged in the circumferential direction of the image recording drum 36. Are arranged along. Details of the image recording unit 16 will be described later.

  Further, on the downstream side in the conveyance direction with respect to the image recording drum 36, a conveyance drum 40 is provided that receives the sheet member P conveyed by the image recording drum 36 and conveys it toward the drying unit 18 by the holding member 30. It has been.

  The drying unit 18 is provided with a drying drum 42 that receives the sheet member P conveyed by the conveying drum 40 by the holding member 30 while rotating and conveys the sheet member P along the outer peripheral surface. Further, a halogen heater 44 and a hot air nozzle 46 used for drying the sheet member P conveyed along the outer peripheral surface of the drying drum 42 are disposed above the drying drum 42 in the vertical direction. With this configuration, the moisture contained in the sheet member P in order to enhance the film quality of the drawing portion on which the image is formed while the sheet member P is conveyed by the drying drum 42, the heat from the halogen heater 44 and the hot air nozzle 46. Due to the warm air from the air, it decreases (becomes dry). Thereby, the film quality strength of the image formed on the sheet member P is improved.

  Further, on the downstream side in the conveyance direction with respect to the drying drum 42, a conveyance drum 48 is provided that receives the sheet member P conveyed by the drying drum 42 and conveys it toward the fixing unit 20 by the holding member 30. Yes.

  The fixing unit 20 is provided with a fixing drum 50 that receives the sheet member P conveyed by the conveying drum 48 by the holding member 30 while rotating and conveys the sheet member P along the outer peripheral surface. Further, the halogen heater 61 used for heating (preliminary heating) the image forming surface of the conveyed sheet member P so as to face the outer peripheral surface of the fixing drum 50, and the outer peripheral surface of the fixing drum 50. A fixing roll 63 that is in pressure contact with each other, and a check pattern on the sheet member P, an in-line sensor 65 that measures a moisture amount, a surface temperature, a glossiness, and the like are provided in this order.

  Further, on the downstream side in the conveyance direction with respect to the fixing drum 50, the sheet member P conveyed by the fixing drum 50 is received by the holding member 30 while rotating, and further, the sheet member P is taken along the curved guide plate 54. A transport drum 52 for discharging to the discharge unit 22 is provided.

  Further, a seasoning device 58 that adjusts the sheet member P to the surrounding environment is provided in the paper discharge unit 22 from which the sheet member P is discharged by the transport drum 52.

  With the above configuration, as shown in FIG. 5, the sheet member P supplied by the sheet feeding unit 12 is received by the processing liquid coating drum 28 by the holding member 30 and conveyed along the outer peripheral surface of the processing liquid coating drum 28. Is done. Then, the processing liquid coating device 32 applies the processing liquid to the image forming surface of the sheet member P conveyed along the outer peripheral surface of the processing liquid coating drum 28.

  Further, the sheet member P coated with the processing liquid is transferred to the rotating conveyance drum 34 and conveyed along the outer peripheral surfaces of the rotating conveyance drum 34 and the image recording drum 36. In the image recording unit 16, each color droplet discharge head 38 discharges droplets of ink or the like onto the image forming surface of the sheet member P conveyed along the outer peripheral surface of the image recording drum 36, thereby forming an image on the sheet member P. Form.

  Further, the sheet member P on which an image is formed on the image forming surface is transferred to the rotating conveying drum 40 and is conveyed along the outer peripheral surfaces of the rotating conveying drum 40 and the drying drum 42. In the drying unit 18, the sheet member P transported along the outer peripheral surface of the drying drum 42 is dried by the heat of the halogen heater 44 and the warm air blown from the warm air nozzle 46. That is, when the moisture contained in the sheet member P is reduced (drys), the film quality of the drawing portion where the image is formed is enhanced.

  The sheet member P heated to a high temperature by the heat of the halogen heater 44 and the warm air blown from the warm air nozzle 46 is transferred to the rotating transport drum 48 and the outer peripheral surfaces of the rotating transport drum 48 and the fixing drum 50. It is conveyed along. In the fixing unit 20, a halogen heater 61 provided facing the fixing drum 50 fixes an image formed on the sheet member P by heat to the sheet member P. Further, the sheet member P conveyed by the fixing drum 50 is pressed against the fixing drum 50 by the fixing roll 63 and passes through the facing portion of the in-line sensor 65. The in-line sensor 65 measures a check pattern, moisture content, surface temperature, glossiness, and the like on the sheet member P that passes therethrough.

  Further, the sheet member P measured by the inline sensor 65 is transferred to the transport drum 52 and discharged along the guide plate 54 to the seasoning device 58 provided in the discharge unit 22. The sheet member P discharged to the seasoning device 58 is adapted to the surrounding environment by blowing air or the like.

(Main part configuration)
Next, the image recording unit 16 will be described.

  As shown in FIGS. 1 and 3, an arc-shaped jacket plate 100 is attached to the outer periphery of the image recording drum 36 provided in the image recording unit 16. The outer peripheral surface of the jacket plate 100 is a conveying surface 100A that supports the sheet member P. Further, the jacket plate 100 is formed with a plurality of through holes 102 penetrating the front and back (see FIG. 3).

  In addition, a pressing roll 70 is provided as an example of a pressing member that presses the sheet member P conveyed to a position facing the droplet discharge heads 38 of each color against the conveying surface 100A. The pressing roll 70 is configured to be pressed against the transport surface 100A by a predetermined pressing force and to be rotated in contact with the transport surface 100A.

  Further, as shown in FIG. 1, an adsorption region on the upper side in the vertical direction of the rotation shaft 36 </ b> A of the image recording drum 36 that attracts and adsorbs the sheet member P pressed against the conveyance surface 100 </ b> A by the pressing roll 70 onto the conveyance surface 100 </ b> A. 108 is provided. Specifically, the suction region 108 is formed so as to be sandwiched between a pair of partition plates 106 extending in the radial direction of the rotation shaft 36A in the front view shown in FIG.

  In addition, a suction device 110 that sucks the outside air through the through-hole 102 of the suction region 108 to suck the sheet member P onto the transport surface 100A is provided. The adsorption device 110 includes a pump 104 for sucking air, a hollow first air chamber 112 disposed in the adsorption region 108, and a tubular hose 114 communicating with the pump 104 and the first air chamber 112. It is prepared for. The wall plate of the first air chamber 112 is formed with a plurality of suction holes (not shown) for sucking outside air.

  On the other hand, a discharge area 116 for discharging the air sucked by the suction device 110 to the outside is provided on the lower side in the vertical direction of the rotation shaft 36A of the image recording drum 36. Specifically, the discharge region 116 is formed so as to be sandwiched between a pair of partition plates 118 extending in the radial direction of the rotation shaft 36A in front view.

  Further, a discharge device 120 for discharging the air sucked by the adsorption device 110 to the outside through the through hole 102 of the discharge region 116 is provided. The discharge device 120 is in communication with the first air chamber 112 through a tubular flow path 124 and is disposed in the discharge region 116, a compressor 128 that compresses and discharges air, a compressor 128, A tubular hose 130 communicated with the second air chamber 126 is provided. The wall plate of the second air chamber 126 is formed with a plurality of discharge holes (not shown) for discharging air to the outside.

  With the above configuration, the pump 104 and the compressor 128 are operated, and the flow path 124 is appropriately opened or closed, so that air is sucked from the suction hole of the first air chamber 112 and is externally passed through the through hole 102 of the adsorption region 108. Air is aspirated. Further, the air sucked by the adsorption device 110 is discharged from the discharge hole of the second air chamber 126 and is discharged to the outside through the through hole 102 of the discharge region 116.

  Further, a detection sensor 72 for detecting the floating of the sheet member P conveyed by the conveyance surface 100A is provided downstream of the pressing roll 70 in the conveyance direction and upstream of the droplet discharge head 38 in the conveyance direction. It has been. As shown in FIG. 3, two detection sensors 72 are provided in the width direction of the sheet member P with the image recording drum 36 interposed therebetween.

  Specifically, the detection sensor 72 includes a detection sensor 72A that emits laser light and a detection sensor 72 that receives the laser light, and detects the floating of the sheet member P based on the amount of light received by the detection sensor 72B. It is supposed to be.

  On the other hand, as shown in FIG. 1, on the upstream side of the pressing roll 70 in the conveying direction, the sheet member P pressed against the conveying surface 100 </ b> A by the pressing roll 70 is sucked and pressed by the pressing roll 70. A tension applying device 74 is provided as an example of a suction unit that applies tension.

  The tension applying device 74 includes a paper guide 76, a pump 78, and a communication pipe 80 that allows the paper guide 76 and the pump 78 to communicate with each other. The sheet guide 76 is a hollow member having a trapezoidal shape in which the conveying surface 100A side is widened in a front view, and extends along the width direction of the sheet member P (hereinafter simply referred to as the width direction). The paper guide 76 has a length equivalent to that of the image recording drum 36 in the width direction.

  Further, the surface on the conveyance surface 100A side of the sheet guide 76 is flat, and serves as a guide surface 82A that sucks the image forming surface of the sheet member P and guides the conveyance of the sheet member P. The guide surface 82A is arranged along the tangent line T of the image recording drum 36 at the contact point H between the pressing roll 70 and the transport surface 100A in a front view.

  Further, as shown in FIG. 4, two suction holes 86 penetrating the front and back of the guide plate 82 are formed in the guide plate 82 on which the guide surface 82 </ b> A is formed. Specifically, each suction hole 86 is provided so as to extend in the width direction of the sheet member P, and a central portion in the longitudinal direction is bent and protrudes toward the upstream side in the conveyance direction.

  Further, in the paper guide 76, a vacuum prevention hole 88 </ b> A penetrating the front and back of the ceiling plate 88 is formed in the ceiling plate 88 provided to face the guide plate 82. The vacuum prevention hole 88 </ b> A adjusts the internal pressure of the paper guide 76 to suppress an excessive suction force from acting on the suction hole 86.

  With this configuration, by operating the pump 78 (see FIG. 1), air inside the paper guide 76 (hollow part) is sucked and air is sucked from the suction hole 86 formed in the guide surface 82A. It has become.

  Further, as shown in FIGS. 1 and 3, wind is sent between the paper guide 76 of the tension applying device 74 and the conveying surface 100A, and the rear end side of the sheet member P is moved away from the conveying surface 100A. A plurality of blower fans 90 as an example of the blower member are provided along the width direction.

  Specifically, the blower fan 90 is disposed on the opposite side of the image recording drum 36 with the sheet member P being conveyed therebetween. Further, each blower fan 90 is fixed to a shaft member 92 that constitutes the transport drum 34 and does not rotate and moves via a bracket 94 that extends in the radial direction of the shaft member 92. That is, the holding member 30 provided on the transport drum 34 rotates around the shaft member 92 whose position is fixed.

  Further, an operation control unit 96 that controls the operation of the blower fan 90 is provided. The operation control unit 96 operates the blower fan 90 after the rear end portion of the conveyed sheet member P has passed a position facing the blower fan 90. A detection member (not shown) that detects that the rear end of the conveyed sheet member P passes through a position facing the blower fan 90 is provided between the sheet guide 76 and the conveyance drum 34. .

  Further, when the size of the sheet member P is small, the operation control unit 96 operates the blower fan 90 disposed on the outer side in the width direction of the sheet member P compared to the case where the size of the sheet member P is large. It is supposed to stop. That is, the operation control unit 96 selects the blower fan 90 to be operated based on the size of the sheet member P.

  Further, an air volume control unit 98 that controls the amount of air sent between the paper guide 76 and the conveyance surface 100A by the blower fan 90 is provided. When the weight (basis weight) per unit area of the sheet member P is heavy, the air volume control unit 98 is compared with the case where the weight per unit area of the sheet member P is light. Increase the air volume generated by Further, the air volume control unit 98 increases the air volume generated by the blower fan 90 when the size of the sheet member P is large compared to when the size of the sheet member P is small. Further, the air volume control unit 98 is configured to increase the air volume generated on the outer side in the width direction of the sheet member P than the air volume generated on the inner side in the width direction of the sheet member P.

Further, the air flow q of the blower fan controlled by the air flow control unit 98 is 0.02 [m ² / min] or more per unit length in the width direction of the sheet member P.

Note that the upstream wind speed v [m / s] between the transport surface 100A and the paper guide 76 in the transport direction and between the transport surface 100A and the paper guide 76 in a front view (indicated by an arrow in FIG. 1). Is used to calculate the air volume q = h · v [m ² / min] per unit length in the width direction of the sheet member P using the upstream distance h (see FIG. 1).

(Effects of main components)
Next, the operation and effect of the image recording unit 16 will be described.

  As shown in FIG. 1, the image recording drum 36 receives the sheet member P conveyed by the conveying drum 34 by the holding member 30 while rotating, and conveys it along the conveying surface 100A.

  As shown in FIG. 2A, the sheet member P that is conveyed while its leading end is held by the holding member 30 is pressed against the conveying surface 100A of the image recording drum 36 by a rotating pressing roll 70.

  As shown in FIG. 1, the suction device 110 sucks outside air through the through hole 102 of the suction region 108. Thereby, the sheet member P pressed against the conveyance surface 100A by the pressing roll 70 is attracted to the conveyance surface 100A.

  Further, after the detection sensor 72 detects the floating of the sheet member P adsorbed to the conveyance surface 100A by the adsorption device 110, the droplet discharge heads 38 of the respective colors drop ink droplets such as ink on the image forming surface of the sheet member P. To form an image on the sheet member P.

  Here, the pump 78 of the tension applying device 74 provided on the upstream side in the transport direction with respect to the pressing roll 70 is operated simultaneously with the operation of the image forming apparatus 10. Therefore, the sheet member P conveyed by the image recording drum 36 is sucked into the suction hole 86 (see FIG. 4) at a position immediately before being pressed against the conveying surface 100A by the pressing roll 70. The sheet member P is conveyed while being attracted to the guide surface 82A of the paper guide 76. Specifically, the sheet member P is transported downstream in the transport direction by sliding the image forming surface of the sheet member P in contact with the guide surface 82A.

  Thus, since the sheet member P is sucked at a position immediately before being pressed against the conveying surface 100A by the pressing roll 70, tension (back tension) acts on the sheet member P pressed against the conveying surface 100A.

  On the other hand, as shown in FIGS. 1, 2 </ b> B and 2 </ b> C, the operation control unit 96 passes the position where the rear end portion of the sheet member P conveyed by the image recording drum 36 faces the blower fan 90. Then, the blower fan 90 is operated. Further, the air volume control unit 98 controls the air volume generated by the blower fan 90 based on the weight (basis weight) and size of the sheet member P.

  Then, the blower fan 90 sends air between the paper guide 76 and the transport surface 100A, and moves the rear end side of the sheet member P in a direction away from the transport surface 100A.

  Accordingly, the tension is applied to the vicinity of the rear end of the sheet member P by being sucked by the tension applying device 74 to the rear end side of the sheet member P. Then, the sheet member P comes in contact with the conveyance surface 100A in order from the front end portion of the sheet member P to which tension is applied, and is pressed against the conveyance surface 100A by the pressing roll 70.

  As described above, the sheet member P contacts the conveyance surface 100A in order from the front end portion of the sheet member P to which tension is applied, and is pressed against the conveyance surface 100A by the pressing roll 70. Even if it exists, it can suppress that a sheet member P produces a wrinkle.

  In addition, since a plurality of blower fans 90 are provided along the width direction of the sheet member P to be conveyed, the blower fan 90 has an air flow between the paper guide 76 and the conveyance surface 100A across the width direction. Can be sent in.

  Further, the operation control unit 96 operates the blower fan 90 after passing the position where the rear end portion of the conveyed sheet member P faces the blower fan 90. For this reason, it is possible to suppress the rear end side of the sheet member P from being grounded (contacted) with the conveyance surface 100A due to the wind generated in the blower fan 90.

  Moreover, since the operation control unit 96 selects the blower fan 90 to be operated based on the size of the sheet member P, it is possible to reduce useless power.

  Further, since the air volume control unit 98 changes the air volume generated by the blower fan 90 based on the weight (basis weight) per unit area of the sheet member P, the blower fan 90 effectively The rear end side can be separated from the transport surface 100A.

  Further, since the air volume control unit 98 changes the air volume generated by the blower fan 90 based on the size of the sheet member P, the blower fan 90 effectively separates the rear end side of the sheet member P from the conveyance surface 100A. be able to.

  Further, the air volume control unit 98 increases the air volume generated on the outer side in the width direction of the sheet member P than the air volume generated on the inner side in the width direction of the sheet member P. For this reason, when the corner portion of the rear end edge of the sheet member P is wavy (curled), the rear end side of the sheet member P can be effectively moved in a direction away from the conveying surface 100A. it can.

Further, since the amount of air generated by the blower fan 90 is 0.02 [m ² / min] or more per unit length in the width direction of the sheet member P, the rear end side of the sheet member P is effectively transferred to the conveying surface. Can be separated from 100A.

  Next, an example of the image forming apparatus 150 according to the second embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 6, in the second embodiment, unlike the first embodiment, the blower fan is not provided, and the wind generated by the flow of air discharged by the discharge device 120 is conveyed to the paper guide 76. A guide member 152 is provided as an example of a blowing unit that leads between the surface 100A.

  Specifically, an arcuate guide member 152 is provided across the width direction of the sheet member P so as to face the conveying surface 100A of the discharge area 116. One end of the guide member 152 on the upstream side in the rotation direction of the image recording drum 36 is bent toward the transport surface 100A. On the other hand, the other end portion of the guide member 152 extends toward the facing portion 156 between the image recording drum 36 and the transport drum 34.

  Further, an air volume control unit 158 that controls the output of air by the discharge device 120 by adjusting the output of the compressor 128 is provided.

  When the weight per unit area of the sheet member P is heavy, the air volume control unit 158 reduces the amount of air discharged by the discharge device 120 as compared with the case where the weight per unit area of the sheet member P is light. Increase (increase airflow). Further, the air volume control unit 158 increases the amount of air discharged by the discharge device 120 when the size of the sheet member P is large compared to when the size of the sheet member P is small (air volume). ).

  With the above configuration, the guide member 152 guides the wind generated by the flow of the air discharged by the discharge device 120 between the paper guide 76 and the transport surface 100A. Therefore, it is necessary to provide a dedicated member for generating the wind. Disappear.

  Further, since the guide member 152 is provided across the width direction of the sheet member P to be conveyed, the wind can be guided between the sheet guide 76 and the conveyance surface 100A along the width direction of the sheet member P. .

  Next, an example of the image forming apparatus 200 according to the third embodiment of the present invention will be described with reference to FIG. In addition, about the same member as 2nd Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  As shown in FIG. 7, in the third embodiment, unlike the second embodiment, the discharge area 204 is not provided on the lower side in the vertical direction of the rotation shaft 36 </ b> A, and the paper is sandwiched by the conveyance surface 100 </ b> A. It is provided on the opposite side of the guide 76. The discharge area 204 is provided with a second air chamber 202 that constitutes a discharge device 206.

  With the above configuration, by operating the discharge device 206, the air sucked by the adsorption device 110 is discharged from the discharge hole of the second air chamber 202 and externally through the through hole 102 (see FIG. 3) of the discharge region 204. To be discharged. Thereby, the rear end side of the sheet member P is separated from the conveying surface 100A.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the first embodiment, the operation control unit 96 and the air volume control unit 98 are set separately. However, it is not necessary to provide them separately, and one control unit having these functions may be set.

  In the above-described embodiment, the tension applying device 74 sucks the sheet member P by sucking external air, but may suck it by electrostatic force or the like.

  Moreover, in the said embodiment, although it did not mention in particular about which site | part of the sheet | seat member P has wavy, it is not limited. For example, the image forming apparatus 10 according to the present embodiment can be used even when the sheet member P is wavy at the rear end portion or when the front end portion or other portions are wavy. By using, wrinkles can be prevented from occurring in the sheet member P.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 34 Conveying drum 36 Image recording drum 38 Droplet discharge head (an example of image forming means)
70 Pressing roll (an example of pressing member)
74 Tension applying device (an example of suction means)
90 Blower fan (an example of a blower / blower member)
96 Operation Control Unit 98 Air Flow Control Unit 100A Conveying Surface 102 Through Hole 110 Adsorption Device 120 Ejection Device 150 Image Forming Device 152 Guide Member (Example of Blowing Unit)
158 Air volume control unit 200 Image forming apparatus 206 Discharge device

Claims (15)

An image recording drum that supports and conveys a sheet-like recording medium on a conveying surface while rotating;
A pressing member that presses a recording medium against the conveyance surface of the image recording drum;
A suction means provided on the upstream side of the pressing member in the conveyance direction of the recording medium, for sucking the recording medium and applying tension to the recording medium;
A blowing means for moving the rear end side of the recording medium sucked by the suction means in a direction away from the conveying surface by sending air; and
An image forming unit arranged to face the transport surface of the image recording drum and forming an image on a recording medium pressed against the transport surface by the pressing member;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the blowing unit sends air between the suction unit and the conveyance surface from an upstream side in the conveyance direction of the recording medium with respect to the suction unit.   The image forming apparatus according to claim 1, wherein the blowing unit sends air between the suction unit and the transport surface from the inside of the image forming drum.   The image forming apparatus according to claim 2, wherein the blowing unit is a blowing member that is disposed on the upstream side in the recording medium conveyance direction with respect to the suction unit and outside the image forming drum. A transport drum for delivering the recording medium to the image forming drum is provided upstream of the image forming drum in the transport direction of the recording medium,
The image forming apparatus according to claim 4, wherein the air blowing member is provided inside the transport drum.   The image forming apparatus according to claim 5, wherein a plurality of the blowing members are provided along a width direction of the recording medium to be conveyed. An operation control unit for controlling the operation of the blowing member is provided,
The image forming apparatus according to claim 4, wherein the operation control unit operates the air blowing member after a rear end portion of the recording medium to be conveyed has passed a position facing the air blowing member. .   The operation control unit stops the operation of the air blowing member disposed outside the recording medium in the width direction when the size of the recording medium is small as compared to when the size of the recording medium is large. The image forming apparatus described. An adsorption device that adsorbs the recording medium pressed against the conveyance surface by the pressing member to the conveyance surface by sucking air through a through-hole formed in the conveyance surface;
A discharge device for discharging the air sucked by the suction device to a place different from the place where the recording medium is sucked, and provided.
The blowing means is
The image forming apparatus according to claim 1, wherein the image forming apparatus is a guide member that guides wind generated by a flow of air discharged by the discharge device between the suction unit and the transport surface.   The image forming apparatus according to claim 9, wherein the guide member receives wind generated by a flow of air discharged by the discharge device through the transport surface and guides the wind along the transport surface.   The image forming apparatus according to claim 10, wherein the guide member is formed by bending a plate member.   The image forming apparatus according to claim 11, wherein the guide member is provided across a width direction of a recording medium to be conveyed. The recording medium is a recording paper,
An air volume control unit for controlling an air volume sent between the suction unit and the transport surface by the blowing unit is provided;
The air volume control unit increases the air volume generated by the blowing unit when the weight per unit area of the recording paper is heavy as compared to when the weight per unit area of the recording paper is light. The image forming apparatus according to claim 1. An air volume control unit for controlling an air volume sent between the suction unit and the transport surface by the blowing unit is provided;
The air volume control unit according to any one of claims 1 to 12, wherein when the size of the recording medium is large, the air volume generated by the blowing unit is increased as compared with a case where the size of the recording medium is small. Image forming apparatus. An air volume control unit for controlling an air volume sent between the suction unit and the transport surface by the blowing unit is provided;
The image forming apparatus according to claim 1, wherein the air volume control unit increases an air volume generated outside in a width direction of the recording medium, more than an air volume generated inside in the width direction of the recording medium.

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