Patent Publication Number: US-2021187969-A1

Title: Inkjet recording apparatus capable of easily performing height adjustment

Description:
INCORPORATION BY REFERENCE 
     This application is based on and claims the benefit of priority from Japanese Patent Application No. 2019-231809 filed on Dec. 23, 2019, the contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure relates to an inkjet recording apparatus. 
     In an inkjet recording apparatus, a recording head that ejects ink onto a recording medium such as paper and the like may be moved according to various purposes. For example, in a case of performing maintenance on the recording head, the recording head may be moved upward to perform capping or cleaning of the ink ejection surface of the recording head. 
     For example, a typical inkjet recording apparatus has a line head moving mechanism that moves a line head, which is a recording head, in the vertical direction. This line head moving mechanism is provided with a rack and pinion mechanism on each of a front plate and a rear plate. The front plate and the rear plate are attached to the front and rear of a raising/lowering unit having a line head group. The front and rear of the raising/lowering unit are both end portions in the paper width direction orthogonal to the paper conveying direction. When a gear that engages with the rack is rotated by a motor, the line head group moves up and down together with the raising/lowering unit. 
     SUMMARY 
     The inkjet recording apparatus according to the present disclosure includes a recording unit, a frame unit, a vertical drive unit, and a conveying unit. The recording unit has a recording head that ejects ink onto a recording medium and records an image. The frame unit supports the recording unit so as to be movable in a vertical direction. The vertical drive unit moves the recording unit in a vertical direction. The conveying unit is arranged below the recording unit and conveys a recording medium. The frame unit supports the recording unit via vertical guide members extending in the vertical direction and arranged at each of both end portions in the width direction of the recording unit that is orthogonal to a conveying direction of the recording medium. The vertical drive unit is arranged at both end portions in the width direction of the recording unit and includes a ball screw unit that has two screw shafts extending in the vertical direction, and connected with the recording unit such that the recording unit is able to move in the vertical direction; a timing belt that is wound around two pulleys that are each fixed to a screw shaft; and a motor that rotates the timing belt. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional front view of an inkjet recording apparatus of an embodiment according to the present disclosure. 
         FIG. 2  is a schematic plan view of the surroundings of a recording unit of the inkjet recording apparatus of  FIG. 1 . 
         FIG. 3  is an external perspective view of the surroundings of the recording unit of the inkjet recording apparatus of  FIG. 1 . 
         FIG. 4  is a schematic cross-sectional front view illustrating the surroundings of the recording unit of the inkjet recording apparatus of  FIG. 1 . 
         FIG. 5  is a perspective view of the recording unit of  FIG. 3  as viewed from the front. 
         FIG. 6  is a perspective view of a frame unit of  FIG. 3  as viewed from the front. 
         FIG. 7  is a perspective view of a frame unit of  FIG. 3  as viewed from the rear. 
         FIG. 8  is a perspective view of the recording unit of  FIG. 3  as viewed from above. 
         FIG. 9  is a perspective view of the recording unit of  FIG. 3  as viewed from below. 
         FIG. 10  is a schematic plan view of a vertical drive unit of the recording unit of  FIG. 4 . 
         FIG. 11  is a side view of the recording unit of  FIG. 3 . 
         FIG. 12  is a side view of the recording unit of  FIG. 3 , and illustrates a state in which the recording unit is raised. 
         FIG. 13  is a partial perspective view of the surroundings of the recording unit of  FIG. 3 , and illustrates a state in which the recording unit is raised. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the following contents. 
       FIG. 1  is a schematic cross-sectional front view of an inkjet recording apparatus  1  of an embodiment.  FIG. 2  is a schematic plan view of the surroundings of a recording unit  4  of the inkjet recording apparatus  1  of  FIG. 1 . The inkjet recording apparatus  1  is, for example, an inkjet recording type printer. The inkjet recording apparatus  1  is connected, for example, between a paper supply device  101  and a paper post-processing device  102 . 
     The paper supply device  101  accommodates a plurality of sheets of paper (recording medium). The paper supply device  101  separates the sheets of paper one by one and feeds them to the inkjet recording apparatus  1  at the time of recording by the inkjet recording apparatus  1 . The inkjet recording apparatus  1  receives the paper fed out by the paper supply device  101  from a paper inlet  21 . Note that the inkjet recording apparatus  1  itself may be provided with a paper supply unit. 
     The paper post-processing device  102  receives the paper on which an image is recorded by the inkjet recording apparatus  1 . The paper post-processing device  102  performs post-processing on the paper as necessary and discharges the paper. The inkjet recording apparatus  1  outputs the paper on which the image is recorded from a paper outlet  22  to the paper post-processing device  102 . Note that the inkjet recording apparatus  1  itself may be provided with a paper discharge tray or the like. 
     As illustrated in  FIGS. 1 and 2 , the inkjet recording apparatus  1  includes a device main body  2 , a paper conveying unit  3 , a recording unit  4 , a drying unit  5 , and a control unit  6 . 
     The paper conveying unit  3  conveys the paper received from the paper supply device  101  via the paper inlet  21  to the recording unit  4  and the drying unit  5 . The paper conveying unit  3  further outputs the recorded and dried paper from the paper outlet  22 . In a case where double-sided recording is performed, the paper conveying unit  3  distributes paper that has been recorded on a first surface and dried to a reverse conveying unit  34  by a branching unit  33 . The paper conveying unit  3  further switches the conveying direction to reverse the front and back of the paper. The paper conveying unit  3  conveys the paper, the front and back of which has been reversed, to the recording unit  4  and the drying unit  5  again. 
     The paper conveying unit  3  has a first belt conveying unit  31  and a second belt conveying unit  32 . The first belt conveying unit  31  and the second belt conveying unit  32  attract and hold the paper on the upper surface of a continuous belt and convey the paper. The first belt conveying unit  31  is arranged below the recording unit  42 , which will be described later, and conveys the paper. The second belt conveying unit  32  is arranged in the drying unit  5  and conveys the paper. 
     The recording unit  4  is arranged on the downstream side in the paper conveying direction of the paper inlet  21 , and on the upstream side in the paper conveying direction of the drying unit  5 . The recording unit  4  faces the paper that is conveyed by being attracted to and held on the upper surface of the belt of the first belt conveying unit  31 , and is arranged above and separated from the first belt conveying unit  31  by a specified space. 
     The recording unit  4  includes recording units  4 B,  4 C,  4 M,  4 Y,  4 X, and  4 Z provided so as to correspond to each of the four colors of black, cyan, magenta, and yellow, and two other colors. The six-color recording units  4 B,  4 C,  4 M,  4 Y,  4 X, and  4 Z are arranged side-by-side along the paper conveying direction. The recording units  4 B,  4 C,  4 M,  4 Y,  4 X, and  4 Z sequentially eject six colors of ink onto paper conveyed by the first belt conveying unit  31 , and record a full-color image or a monochrome image on the paper. The detailed configuration of the recording unit  4  will be described later. 
     The drying unit  5  is arranged on the downstream side in the paper conveying direction of the recording unit  4 , and is provided with the second belt conveying unit  32 . The paper on which the ink image is recorded by the recording unit  4  is attracted to and held on the upper surface of the belt of the second belt conveying unit  32  in the drying unit  5 , and the ink is dried while the paper is being conveyed. 
     The control unit  6  includes a CPU, a storage unit, other electronic circuits, and electronic components. The CPU controls the operation of each component provided in the inkjet recording apparatus  1  based on the control program and data stored in the storage unit. As a result, the control unit  6  performs processing related to the functions of the inkjet recording apparatus  1 . Each of the paper conveying unit  3 , the recording unit  4 , and the drying unit  5  receives commands individually from the control unit  6  and records on paper in conjunction with each other. The storage unit is composed of a combination of a non-volatile storage device and a volatile storage device. The non-volatile storage device is, for example, a program ROM (Read Only Memory), a data ROM, or the like. The volatile storage device is, for example, a RAM (Random Access Memory) or the like. 
     Next, the configuration of the recording unit  4  of the inkjet recording apparatus  1  will be described with reference to  FIGS. 3 to 13  in addition to  FIGS. 1 and 2 .  FIG. 3  is an external perspective view of the surroundings of the recording unit  4  of the inkjet recording apparatus  1  of  FIG. 1 .  FIG. 4  is a schematic cross-sectional front view of the surrounding of the recording unit  4  of the inkjet recording apparatus  1  of  FIG. 1 .  FIG. 5  is a perspective view of the recording unit  4  of  FIG. 3  as viewed from the front.  FIG. 6  is a perspective view of the frame unit  41  of  FIG. 3  as viewed from the front.  FIG. 7  is a perspective view of the frame unit  41  of  FIG. 3  as viewed from the rear.  FIG. 8  is a perspective view of the recording unit  42  of  FIG. 3  as viewed from above.  FIG. 9  is a perspective view of the recording unit  42  of  FIG. 3  as viewed from below.  FIG. 10  is a schematic plan view of a vertical drive unit  43  of the recording unit  4  of  FIG. 4 .  FIG. 11  is a side view of the recording unit  4  of  FIG. 3 .  FIG. 12  is a side view of the recording unit  4  of  FIG. 3 , and illustrates a state in which the recording unit  42  is raised.  FIG. 13  is a partial perspective view of the surroundings of the recording unit  4  of  FIG. 3 , and illustrates a state in which the recording unit  42  is raised. 
     Note that in  FIGS. 2, 3, 4, and 5 , the right side in the drawing is the upstream side in the paper conveying direction Dc, and the left side is the downstream side in the paper conveying direction Dc. Moreover, the six-color recording units  4 B,  4 C,  4 M,  4 Y,  4 X, and  4 Z each have the same shape, size, and configuration. Therefore, in the following description, use of the identification code representing each color may be omitted. 
     As illustrated in  FIGS. 2, 3, 4, and 5 , the recording unit  4  includes a frame unit  41 , a recording unit  42 , a vertical drive unit  43 , a maintenance unit  44 , and a conveying direction drive unit  45 . 
     As illustrated in  FIGS. 4 and 5 , the frame unit  41  is arranged around the recording unit  42  and the maintenance unit  44 . The frame unit  41  is a housing that supports the recording unit  42  and the maintenance unit  44 . As illustrated in  FIGS. 5, 6 and 7 , the frame unit  41  includes a front wall portion  411 , a back wall portion  412 , a connecting member  413 , an upper cover  414 , a vertical guide member  415 , and a conveying direction guide member  416 . 
     The front wall portion  411  and the back wall portion  412  are arranged so as to face each other in the paper width direction Dw orthogonal to the paper conveying direction Dc. The front wall portion  411  and the back wall portion  412  are configured by a plate shape extending in the paper conveying direction Dc and the vertical direction. The recording unit  42  and the maintenance unit  44  are located between the front wall portion  411  and the back wall portion  412  in the paper width direction Dw. The recording unit  42  and the maintenance unit  44  are supported by the respective wall portions. 
     A plurality of connecting members  413  are arranged between the front wall portion  411  and the back wall portion  412 . The connecting members  413  connect the front wall portion  411  and the back wall portion  412  at a specified distance in the paper width direction Dw. The connecting member  413  has a rod shape extending in the paper width direction Dw. 
     The upper cover  414  is arranged so as to span between the front wall portion  411  and the back wall portion  412  at the upper end portion of the frame unit  41 . The upper cover  414  is configured by a plate shape extending in the paper width direction Dw and the horizontal direction. 
     As shown in  FIGS. 6 and 7 , the vertical guide members  415  and the conveying direction guide members  416  are provided on the inner surface in the paper width direction Dw of both the front wall portion  411  and the back wall portion  412 , respectively. The vertical guide members  415  are arranged in the upstream portion in the paper conveying direction Dc of each of the front wall portion  411  and the back wall portion  412 . The conveying direction guide members  416  are arranged in the lower portions of each of the front wall portion  411  and the back wall portion  412 . 
     The vertical guide members  415  are arranged at both end portions in the paper width direction Dw of the recording unit  42  and extend in the vertical direction. The lower end of the vertical guide member  415  extends to the vicinity of the first belt conveying unit  31 . The frame unit  41  movably supports the recording unit  42  in the vertical direction via the vertical guide members  415 . 
     The conveying direction guide members  416  are arranged at both end portions in the paper width direction Dw of the maintenance unit  44  and extend in the paper conveying direction Dc. The frame unit  41  movably supports the maintenance unit  44  in the paper conveying direction Dc via the conveying direction guide members  416 . 
     As illustrated in  FIGS. 2, 4 and 5 , the recording unit  42  is arranged in the upstream portion in the paper conveying direction Dc of the frame unit  41 . The recording unit  42  is individually supported at each of both end portions in the paper width direction Dw by the front wall portion  411  and the back wall portion  412 . The recording unit  42  is arranged above the first belt conveying unit  31  so as to be movable in the vertical direction. 
     As illustrated in  FIGS. 2 and 4 , the recording unit  42  faces in the vertical direction the paper that is conveyed by being attracted to and held on the upper surface of the belt of the first belt conveying unit  31 . The recording unit  42  is arranged above the first belt conveying unit  31  at a specified interval. As illustrated in  FIGS. 8 and 9 , the recording unit  42  is configured by a rectangular parallelepiped shape extending in the paper width direction Dw. The recording unit  42  has line-type inkjet recording heads  421 . The plurality (for example, three) of recording heads  421  are arranged in a staggered pattern along the paper width direction Dw. 
     As illustrated in  FIG. 9 , the recording head  421  has an ink ejection surface  421   a  on the bottom surface thereof. Furthermore, the recording head  421  includes a plurality of ink ejection nozzles  4211  (see  FIG. 2 ) that open on the ink ejection surface  421   a . The plurality of ink ejection nozzles  4211  are arranged side-by-side along the paper width direction Dw. The plurality of ink ejection nozzles  4211  can eject ink over the entire recording area on the paper. As a result, the recording head  421  ejects ink onto the paper and records an image. 
     Note that as illustrated in  FIG. 5 , an ink supply unit  46  is provided behind the back wall portion  412 . The ink supply unit  46  has a sub tank for storing ink. The ink supply unit  46  supplies ink to the recording head  421  via the connected ink supply paths  461 ,  422  that are formed of a tube or the like. 
     As illustrated in  FIGS. 4, 10 and 11 , the vertical drive unit  43  is provided in the frame unit  41 . The vertical drive unit  43  moves the recording unit  42  in the vertical direction along the vertical guide member  415 . The vertical drive unit  43  includes ball screw units  431 , a pulley  432 , a timing belt  433 , and a motor  434 . 
     The ball screw units  431  are arranged at each of both end portions in the paper width direction Dw of the recording unit  42 . The ball screw unit  431  includes a screw shaft  4311  and a nut portion. The screw shaft  4311  extends in the vertical direction. The nut portion includes a large number of balls, is attached to the screw shaft  4311 , and is connected to the end portion in the paper width direction Dw of the recording unit  42 . When the screw shaft  4311  rotates, the recording unit  42  connected to the nut portion moves in the vertical direction along the rotation axis of the screw shaft  4311 . In other words, the recording unit  42  is movably connected in the vertical direction to the ball screw unit  431 . 
     The pulley  432  includes a drive pulley  4321 , driven pulleys  4322 , and a tension pulley  4323 . The drive pulley  4321  is attached to the shaft portion of the motor  434  so as to be aligned with the rotation axis, and is rotated by the motor  434 . The driven pulleys  4322  are attached to the upper ends of each of the two screw shafts  4311  so as to be aligned with the rotation axis. The tension pulley  4323  comes into contact with the outer peripheral portion of the timing belt  433 . 
     The timing belt  433  is wound around the drive pulley  4321  and the two driven pulleys  4322 . Note that the tension of the timing belt  433  may be adjusted by pressing the tension pulley  4323  against the outer peripheral portion of the timing belt  433  to bring them into contact with each other. 
     The motor  434  rotates the timing belt  433  via the drive pulley  4321 . When the timing belt  433  rotates, the two screw shafts  4311  rotate at the same time via each of the two driven pulleys  4322 . As a result, the recording unit  42  moves in the vertical direction while maintaining the horizontal position. 
       FIG. 11  illustrates a state in which the recording unit  42  is arranged at the ink ejection position at the lower end. On the other hand,  FIGS. 12 and 13  illustrate a state in which the recording unit  42  is raised by the vertical drive unit  43 , for example, for maintenance. In this way, the vertical drive unit  43  moves the recording unit  42  in the vertical direction. 
     With the configuration described above, by shifting the engagement of the driven pulleys  4322  and the timing belt  433 , the heights of both end portions in the paper width direction Dw of the recording unit  42  may be individually adjusted. Therefore, it is possible to easily perform height adjustment of both end portions in the paper width direction Dw of the recording unit  42  that has the recording head  421  and that moves in the vertical direction. 
     Note that the recording unit  42  may be freely connected and disconnected with both the vertical guide member  415  and the ball screw unit  431  at both end portions in the paper width direction Dw, respectively. In other words, the recording unit  42  is removable from the frame unit  41  and the vertical drive unit  43 . According to this configuration, by removing the recording unit  42  from the frame unit  41  and the vertical drive unit  43 , the adjustment of the recording unit  42  itself may be easily executed. For example, adjustment of the position of the recording head  421  with respect to the housing of the recording unit  42  may be easily executed. 
     Moreover, the recording unit  4  includes a recording unit  42  that ejects ink of a single color, a frame unit  41  that supports the recording unit  42 , and a vertical drive unit  43  that moves the recording unit  42  in the vertical direction, and records an image having a single color. In the present embodiment, six recording units  4  are arranged side-by-side above the first belt conveying unit  31  along the paper conveying direction Dc and correspond to each of the six colors. 
     With this configuration, the frame unit  41 , the recording unit  42 , and the vertical drive unit  43  are individually grouped for each of the plurality of colors, to be configured as the recording unit  4 . As a result, the positional relationship with each other of the frame unit  41 , the recording unit  42 , and the vertical drive unit  43  may be adjusted independently for each of a plurality of colors. Therefore, it is possible to continuously record high-quality images in a stable manner. 
     Moreover, by unitizing the frame unit  41 , the recording unit  42 , and the vertical drive unit  43  into a unit for each color, it is possible, for example, to perform replacement in units in a case where trouble occurs Therefore, in the inkjet recording apparatus  1 , maintenance may be improved and downtime can be reduced. 
     As illustrated in  FIGS. 2, 4, 5, and 6 , the maintenance unit  44  is arranged below the frame unit  41 . The maintenance unit  44  is individually supported by both the front wall portion  411  and the back wall portion  412  at each of both end portions in the paper width direction Dw. The maintenance unit  44  is arranged above the first belt conveying unit  31  so as to be movable in the horizontal direction. 
     The maintenance unit  44  performs maintenance of the ink ejection surface  421   a  of the recording head  421  in which the ink ejection nozzles  4211  open. During maintenance, the recording unit  42  moves upward. The maintenance unit  44  includes a cap unit  441  and a cleaning unit  442 . 
     At the time of maintenance, the cap unit  441  moves horizontally below the recording unit  42  that is on the upstream side in the paper conveying direction Dc and has moved upward. The cap unit  441  is attached to the lower side of the recording head  421  and is used for capping the ink ejection surface  421   a . By performing capping of the ink ejection surface  421   a , it is possible to suppress the drying and solidification of the ink. 
     During maintenance, the cleaning unit  442  moves horizontally below the recording unit  42  that is on the upstream side in the paper conveying direction Dc and has moved upward. The cleaning unit  442  presses a wiper member into contact with the ink ejection surface  421   a  of the recording head  421 . The cleaning unit  442  moves the wiper member in the paper width direction Dw in order to perform cleaning of the ink ejection surface  421   a . By performing cleaning of the ink ejection surface  421   a , solidified ink and other foreign substances adhering to the ink ejection surface  421   a  may be removed. 
     As illustrated in  FIG. 4 , the conveying direction drive unit  45  is provided in the frame unit  41 . The conveying direction drive unit  45  moves the maintenance unit  44  along the paper conveying direction Dc along the transport direction guide member  416  below the recording unit  42  that has been moved upward. 
     More specifically, the conveying direction drive unit  45  individually moves each of the cap unit  441  and the cleaning unit  442  along the paper conveying direction Dc below the recording unit  42  that has been moved upward. The conveying direction drive unit  45 , similar to the vertical drive unit  43 , includes a ball screw unit, a pulley, a timing belt, and a motor. These are provided for individually moving the cap unit  441  or the cleaning unit  442 . 
     With the configuration described above, the recording unit  42  and the maintenance unit  44  are individually grouped for each of a plurality of colors and are included in the recording unit  4 . This makes it possible to independently adjust the positional relationship with each other between the recording unit  42  and the maintenance unit  44  for each of a plurality of colors. Therefore, it is possible to continuously record high-quality images in a stable manner. 
     Moreover, by unitizing the recording unit  42  and the maintenance unit  44  into a unit for each color, it is possible, for example, to perform replacement in units in a case where trouble occurs Therefore, in the inkjet recording apparatus  1 , maintenance may be improved and downtime can be reduced. 
     To summarize the above, the following effects may be obtained. 
     In a typical technique, for example, in a case where the height shifts before and after a line head group due to thermal or mechanical aging, there is a problem in that height adjustment cannot be easily performed. Here, the front and back refer to both end portions in the paper width direction. Moreover, this is because a rack and pinion mechanism is used to move the line head group in the vertical direction. As a result, the line head group becomes tilted, problems such as image unevenness or the like occur in the front-rear direction, and there is a risk that the image quality may deteriorate. 
     According to the present disclosure, an inkjet recording apparatus is provided that is capable of easily performing height adjustment of both end portions in the width direction of a recording medium of a recording unit that has a recording head and that moves in the vertical direction. 
     In other words, according to the configuration of the present disclosure, the heights of both end portions in the width direction of the recording unit can be individually adjusted by shifting the engagement between the pulleys and the timing belt. Therefore, it is possible to easily perform height adjustment of both end portions in the width of a recording unit that has a recording head and that moves in the vertical direction. 
     Embodiments according to the present disclosure have been described above; however, the scope of the present disclosure is not limited to these embodiments, and various modifications may be made without departing from the gist of the invention. 
     As industrial applicability, the technique according to the present disclosure may be applied to an inkjet recording apparatus.