Patent Publication Number: US-2012038727-A1

Title: Inkjet printer and ink ejecting method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from: U.S. Provisional Application No. 61/372,666 filed on Aug. 11, 2010, the entire contents of each of which are incorporated herein reference. 
    
    
     FIELD 
     Embodiments described herein relate generally to an inkjet printer and an ink ejecting method for preventing nozzles from clogging. 
     BACKGROUND 
     An inkjet printer includes an endless device which is configured by a rotating drum or belt, and inkjet heads which are arranged along a circumferential surface of the endless device. 
     In inkjet printers in the related art, an ink ejecting operation was performed periodically or at a predetermined time, in order to prevent the nozzles of the inkjet head from clogging. Since a head is relatively fixed to an endless device of a line head-type printer, there is no standby position for the inkjet head. For this reason, there is a problem in the line head-type printer that the endless device, paper sheets, or the like, may be contaminated by ejected ink when ink is ejected from the inkjet head in order to prevent clogging of the nozzle. In order to solve this problem, there is disclosed an inkjet printer in which a recessed portion for receiving waste ink is formed on a part of the circumferential surface of the endless device of a drum or the like. In the inkjet printer, the ink ejected from the inkjet head is received in the recessed portion. However, when such a recessed portion is formed on the circumferential surface of the endless device, there is a limit on the position for holding sheets, since a part of the circumferential surface of the endless device become discontinuous. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view for schematically showing an inside of an inkjet printer according to a first embodiment; 
         FIG. 2  is a perspective view for showing an endless device, a head unit of the inkjet printer shown in  FIG. 1 ; 
         FIG. 3  is a side view showing a state where the head unit of the inkjet printer shown in  FIG. 1  moves in a direction away from the endless device; 
         FIG. 4  is a side view showing a state where a tray of the inkjet printer shown in  FIG. 1  moves in a direction toward the head unit; 
         FIG. 5  is a side view which shows a state where the tray of the inkjet printer shown in  FIG. 1  is moved to a position beyond a cleaning mechanism; 
         FIG. 6  is a block diagram which shows a configuration of a controller of the inkjet printer shown in  FIG. 1 ; 
         FIG. 7  is a flow chart which shows an ejecting sequence of ink which is performed by the controller of the inkjet printer shown in  FIG. 1 ; 
         FIG. 8  is a side view which shows a part of an inkjet printer according to a second embodiment; 
         FIG. 9  is a side view which shows a part of an inkjet printer according to a third embodiment; and 
         FIG. 10  is a side view which schematically shows an inkjet printer according to a fourth embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, an inkjet printer includes an endless device, inkjet heads, a tray, a tray moving mechanism, and a controller. The endless device is configured by a drum or a belt, has a circumferential surface which adsorbs a sheet, and rotates in a predetermined direction. The inkjet head is arranged to face the circumferential surface of the endless device, and defines a clearance between the inkjet head and the circumferential surface. The tray is moved in a circumferential direction of the endless device along the circumferential surface of the endless device. The tray can move in the clearances, which is between a position where the tray faces the inkjet head and a position where the tray does not face the inkjet head. The tray moving mechanism moves the tray in the circumferential direction, independently from the endless device. The controller allows the inkjet head to eject ink, if the tray moves to a position corresponding to the inkjet head. 
     Hereinafter, an inkjet printer according to a first embodiment will be described with reference to  FIGS. 1 to 7 . 
       FIG. 1  shows an inkjet printer  10 . The inkjet printer  10  includes a housing  11 , an endless device  12 A configured by a drum  12  which is accommodated in the housing  11 , a sheet receiving unit  13 , a sheet feeding mechanism  14 , a charging roller  15 , a head unit  16 , a neutralizing charger  17 , a sheet discharging mechanism  18 , an operation unit  19  which functions as a display unit, a controller  20 , a power switch  21 , and the like. 
     The endless device  12 A configured by the drum  12  rotates at a constant circumferential velocity in a direction which is shown by an arrow R 1 , around a rotation axis  25  by a rotation mechanism (not shown). A dielectric layer is provided on a circumferential surface  26  of the drum  12 . 
     The sheet receiving unit  13  accommodates a plurality of sheets S such as papers for example as a recording medium. The sheet feeding mechanism  14  includes a sheet feeding roller  30 , a sheet transporting path  31 , and a transporting roller  32 . The charging roller  15  is arranged to face the circumferential surface  26  of the drum  12 . A DC power circuit  42  is connected to the charging roller  15 . When a DC voltage is applied to the charging roller  15  by the DC power circuit  42 , an electric charge is generated for electro-statically adsorbing the sheet S, on the circumferential surface  26  of the drum  12 . 
     The endless device  12 A according to the embodiment has a configuration in which the sheet S is adsorbed by electrostatic adsorption. However, as other embodiments, an endless device which adsorbs the sheet S using negative pressure may be adopted. In such a case, a negative pressure chamber is formed inside the endless device, and the sheet is adsorbed onto the circumferential surface of the endless device by the negative pressure which is generated in the negative pressure chamber. 
     The sheet S which is adsorbed to the circumferential surface  26  of the drum  12  is transported to the head unit  16 . A position of in a rotation direction of the drum  12  is detected by a rotation angle sensor (not shown) of an encoder, or the like. The sheet discharging mechanism  18  includes a transporting guide  35 , a sheet discharging roller  36 , sheet discharging tray  37 , and the like. 
       FIG. 2  is a perspective view which shows the endless device  12 A which is configured by the drum  12  and the head unit  16 . The head unit  16  includes inkjet heads for each color  16   a,    16   b,    16   c,  and  16   d,  which are capable of color printing. All of these inkjet heads  16   a,    16   b,    16   c,  and  16   d,  are line heads which are extended in a width direction (a direction shown by an arrow W 1 , in  FIG. 2 ) of the sheet S. They are attached to a frame  50 , respectively. The inkjet heads  16   a ,  16   b,    16   c,  and  16   d  have a nozzle plate  51  (shown in  FIG. 1 ) which includes a plurality of nozzle holes for ejecting ink. 
     An example of the inkjet heads  16   a,    16   b,    16   c,  and  16   d  includes a piezoelectric element as a driving member. Ink is ejected from nozzle holes of the nozzle plate  51  when the piezoelectric element is deformed by applying a voltage to the piezoelectric element and by adding pressure to the ink. In addition, as another example of the driving member, a heating element may be adopted. When the ink is heated by the heating element, the ink is ejected from the nozzle holes by the pressure of foam which is generated due to the evaporation of the ink. 
     The frame  50  which holds the inkjet heads  16   a ,  16   b,    16   c,  and  16   d  can change a distance X 2  from a rotation center X 1  of the drum  12 (shown in  FIG. 1 ) by a head moving actuator  55 . That is, the frame  50  can be moved between a reference position shown in  FIG. 1  and a retreat position shown in  FIG. 3 , by the head moving actuator  55 . Here, the “reference position” is a position where a first clearance C 1  which is suitable for image forming, is defined between the drum  12  and the inkjet heads  16   a,    16   b,    16   c,  and  16   d,  when the head unit  16  gets closer to the drum  12 . The “retreat position” is a position where a second clearance C 2  which is larger than the first clearance C 1 , is defined between the drum  12  and the inkjet heads  16   a,    16   b,    16   c , and  16   d,  when the head unit  16  is separated from the drum  12 . 
     The inkjet printer  10  according to the embodiment includes a tray  60 , a tray moving mechanism  63  which has a tray moving motor  61  for rotating the tray  60  and a power transmitting unit  62 , a sensor  64  for detecting the tray  60 , and a cleaning mechanism  65 . As shown in 
       FIG. 2 , the tray  60  has an ink receiving unit  60   a  which extends in an axial direction of the rotation axis  25  of the drum  12 , and a pair of arms  60   b  and  60   c  which extends along both side surfaces of the drum  12 . The tray  60  can rotate in a direction shown by arrows Ml and M 2 , around a rotation axis  66  having the same center as that of the rotation axis  25 . The arms  60   b  and  60   c  extend in a radial direction of the drum  12  toward the rotation axis  25  from both ends of the ink receiving unit  60   a.    
     A width W 2  of the ink receiving unit  60   a  (shown in  FIG. 2 ) is larger than a width W 3  in an ink ejection region of the inkjet heads  16   a,    16   b,    16   c,  and  16   d,  such that ink ejected from the inkjet heads  16   a,    16   b,    16   c , and  16   d  can be received. A recessed portion  73  which can receive ink ejected from the inkjet heads  16   a,    16   b ,  16   c,  and  16   d,  is formed in the ink receiving unit  60   a  of the tray  60 . 
     The cleaning mechanism  65  has a wiping member  75  which wipes away ink attached to the tray  60 . The wiping member  75  has the same width as that of the width W 2  (shown in  FIG. 2 ) of the ink receiving unit  60   a.  The ink attached to the tray  60  is removed from the tray  60  when the tray  60  comes into contact with the wiping member  75 . 
       FIG. 1  shows a state where the head unit  16  is positioned at the reference position, and the first clearance C 1  for forming images is defined between the inkjet heads  16   a,    16   b,    16   c,  and  16   d  and the drum  12 .  FIG. 3  shows a state where the second clearance C 2  for inserting the tray  60 , is defined between the drum  12  and the inkjet heads  16   a,    16   b,    16   c,  and  16   d,  by moving the head unit  16  to the retreat position. 
       FIG. 4  is a side view showing a state where the tray  60  is moved toward the head unit  16 .  FIG. 5  shows a state where the tray  60  is moved to a turning position P x  beyond the cleaning mechanism  65 . In this manner, the tray  60  can rotate around the rotation axis  25  to the turning position P x  shown in  FIG. 5  through an intermediate position shown in  FIG. 4 , from the home position p o  shown in  FIG. 3  independently from the drum  12 . In addition, it is possible to return to the home position p o ) shown in  FIG. 3  from the turning position P x  shown in  FIG. 5 . 
       FIG. 6  is a block diagram showing a configuration of the controller  20  of the inkjet printer  10  according to the embodiment. The controller  20  includes a CPU (Central Processing Unit)  80  which functions as a processor. The CPU  80  is connected with a ROM (Read Only Memory)  82 , a RAM (Random Access Memory)  83 , a communication interface  84 , a controller  85  for the charging roller, a controller  86  for display and operation, a sensor input and output port  87 , a driver  88  for the transport roller motor, a driver  89  for the drum rotating motor, a driver  90  for the tray moving motor, a driver  91  for the paper discharging roller motor, a controller  92  for the inkjet head, and a controller  93  for moving the head, through a bus line  81 . 
     A program for controlling the CPU  80  or various fixed data is stored in the ROM  82 . Various memory areas for storing various data which is necessary for image forming, are formed in the RAM  83 . The communication interface unit  84  controls data communication which is performed between the interface unit and external devices, through a communication line. The controller  85  for the charging roller controls DC voltage supplied to the charging roller  15 . The controller  86  for display and operation controls the operation unit  19  which serves as a display unit having a touch panel, as well. It is possible to store information which is necessary for image forming, in the RAM  83 , by controlling the operation unit  19 . The sensor input and output port  87  is connected to various sensors (for example, the sensor  64 ). 
     The driver  88  for the transport roller motor drives a motor  30   a  for the sheet feeding roller  30  and a motor  32   a  for the transport roller  32 . The driver  89  for the drum rotation motor drives a motor  12   a  for driving the drum  12 . The driver  90  for the tray moving motor drives a motor  61  for moving the tray. The driver  91  for the sheet discharging roller motor drives a motor  36   a  for rotating the sheet discharging roller  36 . The controller  92  for the inkjet head controls an ink ejecting operation of the inkjet heads  16   a,    16   b ,  16   c,  and  16   d.  The controller  93  for moving heads drives the actuator  55  for moving heads. 
     Hereinafter, an outline of the image forming processing by the inkjet printer  10  according to the embodiment will be described with reference to  FIG. 1 . The sheet S accommodated in the sheet receiving unit  13  is transported toward the charging roller  15  by the sheet feeding mechanism  14 . The sheet S is supplied between the circumferential surface  26  of the drum  12  and the charging roller  15 . A DC voltage is applied to the charging roller  15  by the DC power circuit  42 . For this reason, an electric charge with a first polarity is charged to the sheet S, and an electric charge with a second polarity is charged to a dielectric of the drum  12 . Due to the charges, the sheet S is electro statically adsorbed to the drum  12 . 
     The sheet S which is adsorbed to the circumferential surface  26  of the drum  12  is moved in a rotation direction R 1 . In a case of color printing, when the sheet S reaches the first inkjet head  16   a,  a first color ink is ejected to the sheet S from the first inkjet head  16   a.  The sheet S is rotated while being adsorbed to the drum  12  and reaches the second inkjet head  16   b.  By doing this, a second color ink is ejected to the sheet S from the second inkjet head  16   b . Further, when the drum  12  rotates, a third color ink is ejected to the sheet S from the third inkjet head  16   c . Further, when the drum rotates, a fourth color ink is ejected to the sheet S from the fourth inkjet head  16   d . In this manner, an image is formed on the sheet S while the drum  12  is rotating. That is, the inkjet printer  10  performs color printing by a multi pass system with a line head type. 
     When forming images, the head unit  16  is moved to the reference position shown in  FIG. 1  by the head moving actuator  55 . For this reason, the first clearance C 1  which is suitable for image forming is defined between the sheet S and the nozzle plate  51  of the inkjet heads  16   a,    16   b,    16   c,  and  16   d.  For this reason, it is possible to suppress an influence on the ejection of ink caused by an air flow which is accompanied by the rotation of the drum  12 , and to form a desired image with high quality. 
     An AC voltage is applied to the sheet S printed by the head unit  16 , by the neutralizing charger  17 . In this manner, the adsorption of the sheet S with respect to the drum  12  is reduced. The sheet S is discharged to the sheet discharge tray  37  through the transport guide  35  and the sheet discharge roller  36 . 
     The inkjet printer  10  ejects ink from the inkjet heads  16   a,    16   b,    16   c,  and  16   d  periodically or at a predetermined time, in order to prevent nozzles of the inkjet heads  16   a,    16   b,    16   c,  and  16   d  from being clogged. Hereinafter, a sequence of an ink ejecting process will be described with reference to  FIG. 7 . 
     When the power switch  21  is turned on in Act Si in  FIG. 7 , the tray  60  returns to an origin position in Act S 2 . Returning to the origin position is performed, for example, by making the tray  60  be in contact with a stopper which is provided at a predetermined position. Alternatively, when a sensor  67  (shown in  FIG. 1 ) for detecting a rotation angle, such as an encoder, is provided in the rotation axis  66  of the tray  60 , it is possible to return to the origin position on the basis of a signal from the sensor  67 . 
     In Act S 3 , the tray  60  moves to its home position.  FIG. 1  shows a state where the tray  60  stops at its home position. In addition, its home position may match the origin position. When the tray moving motor  61  is a stepping motor, the tray  60  can be positioned on the basis of the number of pulses which drive the motor. When the tray moving motor  61  is a DC motor, the tray  60  can be positioned on the basis of the time after the tray  60  starts to move. 
     In Act S 4 , it is determined whether or not an ink ejection instruction is given by the CPU  80 . If the ink ejection instruction is given, the process proceeds to Act S 5 . In Act S 5 , the head unit  16  is moved to the retreat position, shown in  FIG. 3 , by the head moving actuator  55 . When the head unit  16  moves to the retreat position, the clearance C 2  having a width through which the tray  60  can pass, is formed between the drum  12  and each inkjet heads  16   a,    16   b,    16   c,  and  16   d.  When the tray moving motor  61  rotates in Act S 6 , the tray  60  moves to a first direction (a direction shown by an arrow M 1  in  FIG. 2 ), toward the head unit  16 . 
     When the sensor  64  detects that the tray  60  passes through, the time when the tray  60  passing through the sensor is recorded in Act S 7 , and the process proceeds to Act S 8 . In Act S 8 , an estimate time when the tray  60  reaches the inkjet heads  16   a,    16   b,    16   c,  and  16   d,  is calculated on the basis of the moving speed of the tray  60 , the time when the tray  60  passes through the sensor, and the distance from the sensor  64  to the inkjet heads  16   a,    16   b,    16   c,  and  16   d.    
     In Act S 9 , each inkjet head  16   a,    16   b,    16   c,  and  16   d  sequentially ejects ink according to the time when the tray  60  reaches each inkjet head  16   a,    16   b,    16   c,  and  16   d.  For example, as shown in  FIG. 4 , when the tray  60  reaches the fourth inkjet head  16   d,  the ink is ejected from the fourth inkjet head  16   d  toward the tray  60 , by an ejection signal from the CPU  80 . When the tray  60  reaches the third inkjet head  16   c,  the ink is ejected from the third inkjet head  16   c  toward the tray  60 . When the tray  60  reaches the second inkjet head  16   b , the ink is ejected from the second inkjet head  16   b  toward the tray  60 . When the tray  60  reaches the first inkjet head  16   a,  the ink is ejected from the first inkjet head  16   a  toward the tray  60 . 
     In this manner, the counts are made in Act S 10  when the ink is ejected from inkjet heads  16   a,    16   b ,  16   c,  and  16   d.  If the counts do not reach the predetermined numbers in Act S 11 , the process moves to Act S 13 . 
     When the counts reach the predetermined numbers in Act S 11 , the process proceeds to Act S 12 . In Act S 12 , the tray  60  reaches the cleaning mechanism  65  by further rotating in a first direction (a direction shown by the arrow M 1  in  FIG. 2 ). In the movement, the ink attached to the tray  60  is removed by the wiping member  75  when an ink reception position  60   a  of the tray  60  passes through the wiping member  75  while making contact with the wiping member  75 . 
     It is possible to determine whether the tray  60  passed through the cleaning mechanism  65  based on the time after the tray  60  passed through the sensor  64 . When the tray moving motor  61  is a stepping motor, it is possible to determine whether or not the tray  60  passed through the cleaning mechanism  65  on the basis of the number of pulses. When the sensor  67  for rotation angle, such as the encoder (shown in  FIG. 1 ), is provided in the rotation axis  66  of the tray  60 , it is possible to determine whether or not the tray  60  passed through the cleaning mechanism  65  on the basis of the signal from the sensor  67  for rotation angle. 
     After the tray  60  passed through the cleaning mechanism  65 , the process proceeds to Act S 13 . In Act S 13 , due to a reverse rotation of the tray moving motor  61 , the tray  60  moves in a second direction (a direction shown by the arrow M 2  in  FIG. 2 ), and returns to its home position P o , shown in  FIG. 3 . Further, in Act S 14 , when the head unit  16  returns to the reference position shown in  FIG. 1  by the head moving actuator  55 , the tray return to the first clearance C 1 . 
     In this manner, the inkjet printer  10  according to the embodiment can receive ink which is ejected to prevent the nozzles from being clogged, using the tray  60  which moves independently from the drum  12 . For this reason, since it is not necessary to provide a region for receiving the ink on the circumferential surface  26  of the drum  12 , it is possible to use the entire circumference of the drum  12  as a region for holding the sheet S. 
       FIG. 8  shows a part of an inkjet printer  10 A according to a second embodiment. A tray  60  according to the embodiment is made able to wait at a first home position P 1  which is shown by a solid line and a second home position P 2  shown by two dotted lines in  FIG. 8 . The first home position P 1  is positioned at the rear side of the drum  12  in the rotation direction with respect to a head unit  16 , similarly to the first embodiment. In contrast, the second home position P 2  is set to be positioned in front side of the drum  12  in the rotation direction with respect to the head unit  16 . A first sensor  64   a  and a first cleaning mechanism  65   a  are disposed between the first home position P 1  and the head unit  16 . A second sensor  64   b  and a second cleaning mechanism  65   b  are disposed between the second home position P 2  and the head unit  16 . The other configuration is the same as that of the inkjet printer  10  in the first embodiment. 
     In this inkjet printer  10 A, if an ink ejecting instruction for preventing clogging of the nozzle is given, as in the first embodiment, a second clearance in which the tray  60  is inserted, is defined by moving the head unit  16  to a retreat position using a head moving actuator  55 . In this state, the tray  60  is moved in the first direction M 1  from the first home position P 1  to the second home position P 2 , using the tray moving mechanism  63 . Each inkjet head  16   a,    16   b ,  16   c,  and  16   d  sequentially ejects ink to the tray  60  while the tray  60  is moving toward the second home position P 2 . Subsequently, the tray  60  stops at the second home position P 2 . Due to the returning of the head unit  16  to the reference position, a first clearance is defined between the circumference surface  26  of the drum  12  and the inkjet heads  16   a,    16   b,    16   c , and  16   d.    
     Further, when the next ink ejecting instruction is given, the head unit  16  moves to the retreat position again, using the head moving actuator  55 . The tray  60  moves in the second direction M 2  from the second home position P 2  to the head unit  16 . In addition, when the tray  60  passes through each inkjet head  16   a,    16   b,    16   c , and  16   d,  the ink is sequentially ejected from each inkjet head  16   a,    16   b,    16   c,  and  16   d  to the tray  60 . After that the tray  60  stops at the first home position P 1 . Further, the first clearance is defined between the circumferential surface  26  of the drum  12  and the inkjet heads  16   a,    16   b,    16   c,  and  16   d,  when the head unit  16  is returned to the reference position by the head moving actuator  55 . 
     In the inkjet printer  10 A according to the second embodiment, it is possible to make the head unit  16  wait at the first home position P 1  or the second home position P 2 . In this case, since it is not necessary for the tray  60  to reciprocate to prevent clogging of the nozzle in each ink ejecting operation (one way is enough), it is possible to rapidly move to the image forming process. Since the other configurations and functions in the inkjet printer  10 A are the same as those of the inkjet printer  10  in the first embodiment, the same portions will be denoted by the same reference numerals, and a description thereof will be omitted. 
     In addition, in the first and second embodiments, the head unit  16  is moved to the reference position and the retreat position using the actuator  55 , with respect to the drum  12 . However, in other embodiments, a second clearance for inserting the tray  60  may be defined between the drum  12  and the inkjet heads  16   a ,  16   b,    16   c,  and  16   d,  by moving the drum  12  with respect to the head unit  16 . 
       FIG. 9  shows an inkjet printer  10 B according to a third embodiment. In the inkjet printer  10 B, a clearance C 3  for image forming has a width which can insert a tray  60 . When ejecting ink in order to prevent clogging of the nozzle, it is possible to insert the tray  60  between a drum  12  and inkjet heads  16   a,    16   b,    16   c,  and  16   d,  using the clearance  03 . For this reason, a distance X 3  from X 1  which is a rotation center of the drum  12  to a head unit  16 , is set to be constant. The other configurations and functions of the inkjet printer  10 B are the same as those of the inkjet printer  10  according to the first embodiment, both will be denoted by the same reference numeral at the same portions and a description thereof will be omitted. 
       FIG. 10  shows an inkjet printer  100  according to a fourth embodiment. The inkjet printer  100  has an endless device  100 A formed of a belt  100 . The belt  100  is extended between a first rotation body  101  and a second rotation body  102 , and performs an endless rotation movement (circulation movement) in a direction shown by an arrow R 2 , using a driving mechanism which is not shown. A head unit  16  including inkjet heads  16   a,    16   b,    16   c,  and  16   d,  is disposed in a circumferential direction of the belt  100 . A sheet S which is supplied from a sheet feeding mechanism  103  is supplied between the belt  100  and a charging roller  105  through a transporting path  104 . The charging roller  105  applies electric charge to a dielectric layer which is provided on a circumferential surface of the belt  100 , in order for an electro-static adsorption. On the sheet S, images are formed by the inkjet heads  16   a ,  16   b,    16   c,  and  16   d  while being transported in a direction which is shown by the arrow R 2 , using the belt  100 . The sheet S on which images are formed is discharged from a sheet transporting mechanism  106 . 
     In the inkjet printer  10 C according to the embodiment, a tray  60 ′ is movably disposed along the belt  100 . The tray  60 ′ can be moved in a first direction shown by an arrow M 3  and in a second direction shown by an arrow M 4 . The head unit  16  can be moved to a reference position and a retreat position, using a head moving actuator  55 , similarly to the first embodiment. When an ink ejecting instruction is given, the head moving actuator  55  moves the head unit  16  from the reference position to the retreat position. In this manner, a clearance C 4  through which the tray  60 ′ can pass is defined between the belt  100  and the inkjet heads  16   a,    16   b,    16   c,  and  16   d.  Since the inkjet printer  10 C has the same configurations and functions as those of the inkjet printer  10  of the first embodiment, both will be denoted by the same reference numerals at the same portions and a description thereof will be omitted. 
     As described above, according to each inkjet printer of each embodiment, ink which is ejected for preventing clogging of nozzles can be received using a separate tray which is moving independently from an endless device (a drum or a belt). Since it is not necessary to provide a recessed portion for receiving ink in the endless device, it is possible to use the total circumferential surface of the endless device as a region where the sheet is held. Since the tray is moved periodically or at the predetermined time, independently from the endless device, it is possible to prevent waste ink which is attached to the tray, from being scattered around, even though the endless device rotates. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.