Patent Publication Number: US-7900920-B2

Title: Recording medium transport device in image recording apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a device for transporting a recording medium in an apparatus for recording a predetermined image on the recording medium while transporting the recording medium. 
     2. Description of the Background Art 
     Conventionally, there is known an image recording apparatus in which, while a transport means including rollers, a belt and the like is used to transport a recording medium such as printing paper and the like, ink is ejected from a multiplicity of inkjet nozzles arranged in a direction orthogonal to the transport direction of the recording medium onto the recording medium being transported, to thereby record an image on the recording medium. Such an image recording apparatus is disclosed, for example, in Japanese Patent Application Laid-Open Nos. 2-80269 (1990), 2-187355 (1990), 4-219264 (1992), 2005-131929, and 2004-314605. 
     The image recording apparatus as disclosed in the above-mentioned cited references is capable of doing a large amount of printing at a high speed, but presents a problem in finding difficulties in recording an image with high accuracy on a recording medium because of vibrations created by the rollers, the belt and the like when in operation. 
     To solve the problem, another image recording apparatus has been proposed. While transporting a recording medium principally using a transport means including rollers, a belt and the like, this image recording apparatus records an image on the recording medium after the transport of the recording medium is changed from the transport using the transport means including the rollers, the belt and the like to the transport using a plurality of linear motor mechanisms capable of more accurate transport than using the rollers, the belt and the like at least during image recording. Such an image recording apparatus is capable of doing a large amount of printing at a high speed with high accuracy. 
     However, the image recording apparatus which uses the plurality of linear motor mechanisms to transport the recording medium presents a problem such that, if any one of the linear motor mechanisms malfunctions, the printing process is suspended or there arises a need to transport the recording medium by using the transport means including the rollers, the belt and the like, rather than the linear motor mechanisms, during the image recording. 
     SUMMARY OF THE INVENTION 
     The present invention is intended for an image recording apparatus for recording an image on recording media. 
     According to the present invention, the image recording apparatus comprises: a) an image recording part for recording an image on recording media; and b) a recording medium transport device for transporting the recording media stocked in a predetermined stocking part, the recording medium transport device including b-1) a plurality of tables for holding the recording media thereon, b-2) a supply part for supplying the recording media to each of the plurality of tables, b-3) a plurality of linear motor mechanisms for transporting the plurality of tables in a first transport section including at least an area in which The image recording part records an image on the recording media, b-4) an endless transport mechanism for transporting the plurality of tables in at least a second transport section contiguous with the first transport section and capable of transporting the plurality of tables in the first transport section, and b-5) an unused linear motor mechanism determination part for determining an unused linear motor mechanism to be unused for the transport of the plurality of tables from among the plurality of linear motor mechanisms, the plurality of linear motor mechanisms and the endless transport mechanism being provided so that the plurality of tables are used sequentially and circularly for the transport in the first transport section, wherein, when the unused linear motor mechanism is not determined, all of the plurality of linear motor mechanisms are used for the transport of the plurality of tables in the first transport section, and wherein, when the unused linear motor mechanism is determined, the endless transport mechanism is used as an alternative to transport at least one of the plurality of tables which is to be transported in the first transport section but which is able to be transported by none of the plurality of linear motor mechanisms. 
     If a malfunctioning linear motor mechanism is present because of a breakage, an operation anomaly and the like, the image recording apparatus achieves continuous image recording although the throughput thereof decreases. This suppresses the reduction in productivity, as compared with the complete stop of the image recording apparatus. 
     Preferably, the recording medium transport device further includes b-6) a supply timing determination part for determining supply timing indicative of when to supply the recording media from the supply part in accordance with the condition of transport of the plurality of tables, the supply timing determination part determining the supply timing so that, if an alternative transport table to be transported by the endless transport mechanism as a alternative in the first transport section is present among the plurality of tables, the recording media are not supplied from the supply part to the alternative transport table. The supply part supplies the recording media to the plurality of tables, based on the supply timing determined by the supply timing determination part. 
     During the image recording, no recording medium is supplied to a table which is not transported by the linear motor mechanisms. If a malfunctioning linear motor mechanism is present because of a breakage, an operation anomaly and the like, the image recording apparatus achieves the image recording while maintaining the accuracy of the recorded image although the throughput thereof decreases. 
     Preferably, the number of linear motor mechanisms provided in the recording medium transport device is greater by at least two than a simultaneous transport table count which is the number of tables included among the plurality of tables and transported at the same time in the first transport section. The plurality of linear motor mechanisms except the unused linear motor mechanism are used to transport the plurality of tables in the first transport section when the sum of the number of unused linear motor mechanisms and the simultaneous transport table count is less than the number of linear motor mechanisms provided in the recording medium transport device. The endless transport mechanism is used as an alternative for the transport only when the sum of the number of unused linear motor mechanisms and the simultaneous transport table count is not less than the number of linear motor mechanisms provided in the recording medium transport device. 
     If at least one of the linear motor mechanisms cannot be used for the transport because of a breakage, an operation anomaly and the like, the image recording apparatus is capable of maintaining the accuracy of the recorded image as high as that obtained when there is no unused linear motor mechanism. 
     The present invention is also intended for a recording medium transport device for transporting recording media stocked in a predetermined stocking part in an apparatus including an image recording part and for recording an image on the recording media in the image recording part. 
     According to the present invention, the recording medium transport device comprises: a plurality of tables for holding the recording media thereon; a supply part for supplying the recording media to each of the plurality of tables; a plurality of linear motor mechanisms for transporting the plurality of tables in a first transport section including at least an area in which the image recording part records an image on the recording media; an endless transport mechanism for transporting the plurality of tables in at least a second transport section contiguous with the first transport section and capable of transporting the plurality of tables in the first transport section; and an unused linear motor mechanism determination part for determining an unused linear motor mechanism to be unused for the transport of the plurality of tables from among the plurality of linear motor mechanisms, the plurality of linear motor mechanisms and the endless transport mechanism being provided so that the plurality of tables are used sequentially and circularly for the transport in the first transport section, wherein, when the unused linear motor mechanism is not determined, all of the plurality of linear motor mechanisms are used for the transport of the plurality of tables in the first transport section, and wherein, when the unused linear motor mechanism is determined, the endless transport mechanism is used as an alternative to transport at least one of the plurality of tables which is to be transported in the first transport section but which is able to be transported by none of the plurality of linear motor mechanisms. 
     If a malfunctioning linear motor mechanism is present because of a breakage, an operation anomaly and the like, continuous image recording is achieved although throughput decreases. This suppresses the reduction in productivity, as compared with the complete stop of the image recording apparatus. 
     Preferably, the recording medium transport device further comprises a supply timing determination part for determining supply timing indicative of when to supply the recording media from the supply part in accordance with the condition of transport of the plurality of tables, the supply timing determination part determining the supply timing so that, if an alternative transport table to be transported by the endless transport mechanism as an alternative in the first transport section is present among the plurality of tables, the recording media are not supplied from the supply part to the alternative transport table, wherein the supply part supplies the recording media to the plurality of tables, based on the supply timing determined by the supply timing determination part. 
     No recording medium is supplied to a table which is not transported by the linear motor mechanisms. If a malfunctioning linear motor mechanism is present because of a breakage, an operation anomaly and the like, the image recording is achieved while the accuracy of the recorded image is maintained although throughput decreases. 
     Preferably, the number of linear motor mechanisms provided in the recording medium transport device is greater by at least two than a simultaneous transport table count which is the number of tables included among the plurality of tables and transported at the same time in the first transport section. The plurality of linear motor mechanisms except the unused linear motor mechanism are used to transport the plurality of tables in the first transport section when the sum of the number of unused linear motor mechanisms and the simultaneous transport table count is less than the number of linear motor mechanisms provided in the recording medium transport device. The endless transport mechanism is used as an alternative for the transport only when the sum of the number of unused linear motor mechanisms and the simultaneous transport table count is not less than the number of linear motor mechanisms provided in the recording medium transport device. 
     If at least one of the linear motor mechanisms cannot be used for the transport because of a breakage, an operation anomaly and the like, the accuracy of the recorded image is maintained as high as that obtained when there is no unused linear motor mechanism. 
     It is therefore an object of the present invention to provide an image recording apparatus including a plurality of linear motor mechanisms and capable of operating without interruption if at least one of the linear motor mechanisms malfunctions, and a recording medium transport device for the image recording apparatus. 
     These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic sectional view showing a mechanical construction of an image recording apparatus according to a preferred embodiment of the present invention. 
         FIG. 2  is a perspective view of principal parts of the image recording apparatus of  FIG. 1 . 
         FIG. 3  is a partial perspective view showing components related to the transport of tables in a transport mechanism. 
         FIG. 4  is a partial view showing the coupling between the tables and a chain. 
         FIG. 5  is a vertical sectional view showing principal parts of the transport mechanism. 
         FIGS. 6 and 7  are side views showing coupling mechanisms. 
         FIGS. 8 to 11  are illustrations showing the coupling and decoupling operations of the coupling mechanisms. 
         FIG. 12  is a block diagram showing the construction of a controller. 
         FIGS. 13 to 15  are diagrams for illustration of the transport of ten tables by using five linear motor mechanisms. 
         FIGS. 16 to 18  are diagrams for illustration of the transport of the ten tables by using four of the five linear motor mechanisms. 
         FIGS. 19 to 21  are diagrams for illustration of the transport of the ten tables by using three of the five linear motor mechanisms. 
         FIG. 22  is a flow diagram showing the process of determining the supply timing of recording media. 
         FIG. 23  is a view for illustration of the timing of intermittent supply. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     &lt;Overview of Construction of Image Recording Apparatus&gt; 
       FIG. 1  is a schematic sectional view principally showing a mechanical construction of a fixed head type image recording apparatus  100  for recording an image based on inkjet technology which is a form of an image recording apparatus according to a preferred embodiment of the present invention.  FIG. 2  is a perspective view of principal parts of the image recording apparatus  100 . An XYZ rectangular coordinate system such that a direction in which recording media RM are transported is defined as the positive X direction and a vertically upward direction is defined as the positive Z direction is additionally shown in  FIG. 1 . 
     The image recording apparatus  100  is an apparatus for recording an image on the recording media RM such as, for example, printing paper and the like in accordance with descriptions of previously provided image recording data (data about color density values of pixels constituting an image to be recorded). More specifically, the image recording apparatus  100  is an inkjet printer for recording an image by ejecting inks of different colors (e.g., four colors: C (cyan), M (magenta), Y (yellow), and K (black)) corresponding to a plurality of (in  FIG. 1 , four) inkjet heads  4 H ( 41  to  44 ), respectively, from the inkjet heads  4 H toward the recording media RM. At least two of the plurality of inkjet heads  4 H may eject inks of the same color (e.g., white). 
     An example of the recording medium RM used in this preferred embodiment includes, but is not limited to, typical printing paper (wood free paper). The recording media RM may be made of a material capable of accepting ink, such as a plastic film and the like. 
     The image recording apparatus  100  principally includes: a supply part  2  for supplying the recording media RM from a pre-recording stocking part  10  for stocking therein the recording media RM to be subjected to image recording; a transport mechanism  3  for transporting the recording media RM along a predetermined transport path by using ten tables  20  each capable of holding a recording medium RM thereon; an image recording part  4  for ejecting inks from a multiplicity of inkjet nozzles provided at the lower end of each of the inkjet heads  4 H ( 41  to  44 ) toward the recording media RM passing through the transport path; a discharge part  5  for discharging the recording media RM with an image recorded thereon from the transport path to place the recording media RM into a post-recording stocking part (not shown); a recording medium detection sensor  6  for detecting the presence or absence of the recording media RM on the tables  20  at a predetermined position of the transport path; a scanner  7  for photoelectrically reading the image formed on the recording media RM by the image recording part  4  on the transport path; and a display and manipulation part  9  for displaying operating states and various manipulation means in the image recording apparatus  100  and for allowing an operator to perform input manipulations in accordance with the manipulation menus. The image recording apparatus  100  further includes a controller  8  for controlling the entire operations thereof (with reference to  FIG. 12 ), although not shown in  FIGS. 1 and 2 . 
     In the image recording apparatus  100 , all of the inkjet heads  4 H (the head  41  for black, the head  42  for cyan, the head  43  for magenta, and the head  44  for yellow) are fixedly provided in predetermined positions. Recording of an image is achieved by ejecting inks from the plurality of inkjet nozzles provided at the lower end of each of the inkjet heads  4 H in synchronism with the travel of the recording media RM directly under each of the inkjet heads  4 H. The plurality of inkjet nozzles in each of the inkjet heads  4 H are disposed to eject ink at equal intervals within an image recording area along the width of the recording media RM (in the Y direction as viewed in  FIG. 1 ) toward the recording media RM transported directly thereunder so that the image is recorded on the entire surface of each of the recording media RM. As far as such a requirement is satisfied, the arrangement of the plurality of inkjet nozzles may be determined as appropriate. 
     In such an image recording apparatus  100 , the recording media RM are previously placed on or stocked in the pre-recording stocking part  10  provided in the supply part  2 . The recording media RM placed on or stocked in the pre-recording stocking part  10  are attracted one by one from the top under suction by a supply sucker  13  not shown, and are sequentially supplied to a conveyor  11 . The conveyor  11  transports the supplied recording media RM sequentially to the tables  20  provided in the transport mechanism  3 . In this process, a supply control part  82  to be described later controls when to attract the recording media RM under suction by means of the supply sucker  13  in consideration for the time between the supply of the recording media RM to the conveyor  11  and the transfer of the recording medium RM to the tables  20 . 
     The ten tables  20  are arranged at fixed intervals on an endless track extending along endless guides  25  disposed on opposite side panels  33 , and travels on the endless track along the guides  25 . Each of the tables  20  is capable of holding a single recording medium RM thereon under suction through a suction hole  21 . The recording medium RM supplied from the conveyor  11  to each of the tables  20  is transported on the transport path while being held thereon under suction through the suction hole  21 . Specifically, a vacuum fan  22  is provided under the transport path of the tables  20 , and exhausts air to thereby allow the recording medium RM to be held on each of the tables  20  under suction through the suction hole  21 . 
       FIG. 3  is a partial perspective view showing components related to the transport of the tables  20  in the transport mechanism  3  in further detail.  FIG. 4  is a partial view showing the coupling between the tables  20  and a chain  23  in further detail. More specifically, each of the plurality of tables  20  includes coupling portions  34  (first coupling portions  34   a  and second coupling portions  34   b ) at the four corners thereof. The coupling portions  34  include guide receiving portions  35  ( 35   a  and  35   b ), respectively, for engagement with the guides  25 . The guide receiving portions  35  enable each of the tables  20  to be guided along the guides  25  and to be transported circularly in the transport mechanism  3 . Of the coupling portions  34  of the tables  20 , each the first coupling portions  34   a  provided at the front as viewed in the direction of the travel is provided with a chain coupling portion  36  having a generally triangular hole. The chain coupling portion  36  of each of the tables  20  is brought into engagement with a coupling pin  37  provided on the chain  23 , whereby each of the tables  20  is coupled to the chain  23  looped around a pair of sprockets  26  disposed on the side panels  33  while being spaced a predetermined distance apart from the chain  23 , as indicated by solid lines in  FIG. 4 . 
     As shown in  FIGS. 1 and 2 , a sprocket  27  is disposed on a side of one of the sprockets  26 , and is coupled to a driving sprocket  28  and a driven sprocket  29  with a chain  30 . The driving sprocket  28  is provided so as to be rotated by driving a motor not shown. As the motor not shown is driven, the chain  23  looped around the pair of sprockets  26  accordingly moves around to move the tables  20  along the guides  25 . 
     The vertical position of the chain  23  is changed at some midpoint by combining a pair of sprockets  31  ( 31   a  and  31   b ) and a pair of sprockets  32  ( 32   a  and  32   b ) together. Specifically, the chain coupling portion  36  and the coupling pin  37  are decoupled from each other past a location in which the sprocket  31  a and the sprockets  32   a  are combined. The tables  20  are moved by linear motor mechanisms  24  from this location to a location in which the sprocket  31   b  and the sprocket  32   b  are combined, while being guided by the guides  25 . 
     The linear motor mechanisms  24  are provided so as to enable a linear motor to transport the tables  20  at least during the recording of an image on the recording media RM. In this preferred embodiment, the linear motor mechanisms  24  are provided so as to be able to transport the tables  20  when the image recording part  4  records an image and when the scanner  7  reads an image. This is to enhance the accuracy of travel of the tables  20  (i.e., the accuracy of transport of the recording media RM) during the passage of the tables  20  directly under the image recording part  4  and the scanner  7 . Thus, reductions are achieved in image recording errors (ejection in improper positions) in the image recording part  4  and in reading errors in the scanner  7 . Specifically, a shift in the transport position of the recording media RM results in a shift in the image recording and reading positions. It is hence important to ensure the accuracy of travel of the tables  20 . A section of the transport path in which the tables  20  are transported by the linear motor mechanisms  24  is also referred to hereinafter as a linear transport section. In this preferred embodiment, a maximum of three tables  20  are allowed to be present in the linear transport section at the same time. 
     The transport mechanism  3  in the image recording apparatus  100  according to this preferred embodiment is provided with the five linear motor mechanisms  24 .  FIG. 5  is a vertical sectional view showing principal parts of the transport mechanism  3  and for illustrating the construction of the linear motor mechanisms  24 . For purposes of illustration, only four of the five linear motor mechanisms  24  are shown in  FIG. 5 . The remaining linear motor mechanism  24  not shown is similar in construction to the four linear motor mechanisms  24  shown in  FIG. 5 . The transport mechanism  3  may be provided with more than five linear motor mechanisms  24 . 
     Each of the linear motor mechanisms  24  includes a support plate  62  mounted upright on the main body of the image recording apparatus  100 , a mobile base  63  disposed in opposed relation to the support plate  62 , and a pair of linear guides  64  for coupling the mobile base  63  and the support plate  62  to each other and for horizontally movably guiding the mobile base  63  relative to the support plate  62 . A stator  65  of the linear motor is fixed to the support plate  62 , and a movable element  66  of the linear motor is fixed to the mobile base  63 . 
     In each of the linear motor mechanisms  24 , the mobile base  63  provided with the movable element  66  is attachable to and detachable from a table  20  under the table  20 . With the mobile base  63  provided with the movable element  66  being coupled to the table  20 , the mobile base  63  and the table  20  are moved by changing the magnetic polarity of the stator  65  extending in the direction of the travel of the table  20 . 
     Each of the linear motor mechanisms  24  is provided with a movable element position detection sensor not shown for detecting where the movable element  66  is positioned in a corresponding one of the linear motor mechanisms  24 . 
     Next, the construction of coupling mechanisms for switching the movable element  66  of a linear motor mechanism  24  and a table  20  between a coupled state and a decoupled state will be described. 
       FIGS. 6 and 7  are side views showing the coupling mechanisms.  FIG. 6  shows a coupling mechanism closer to the supply part  2 , and  FIG. 7  shows a coupling mechanism closer to the discharge part  5 .  FIGS. 8 to 11  are illustrations showing the coupling and decoupling operations of the coupling mechanisms. 
     As shown in  FIGS. 8 to 11 , a V-block  60  is attached to the lower surface of the table  2 . A latch lever  68  pivotable about a shaft  67  is provided on the upper end of the mobile base  63  coupled to the movable element  66  of the linear motor as mentioned above. A cam follower  72  is provided on a first end of the latch lever  68 . The cam follower  72  is configured to abut against a recessed portion of the V-block  60  to couple the latch lever  68  and the V-block  60  to each other. A cam follower  71  is provided on a second end of the latch lever  68 . Likewise, a lock lever  69  pivotable about a shaft  73  is provided on the upper end of the mobile base  63 . 
     As shown in  FIGS. 6 and 7 , a movable cam  80  extending in the direction of travel of the table  20  is provided under the above-mentioned cam follower  71 . A pair of fixed cams  78  and  79  are provided on opposite ends of the movable cam  80  as viewed in the direction of the travel of the table  20 . 
     The movable cam  80  is coupled to the main body of the image recording apparatus  100  through pivotal levers  74 . The movable cam  80  has a first end coupled through a link lever  75  to an air cylinder  76 . The movable cam  80  has a second end coupled through a tension spring  177  to the main body of the image recording apparatus  100 . Thus, when the air cylinder  76  is driven to force the movable cam  80  leftwardly as viewed in  FIGS. 6 and 7  through the link lever  75 , the pivotal levers  74  are pivoted to move the movable cam  80  upwardly. 
     When the mobile base  63  is in a first end position closer to the supply part  2 , the cam follower  71  rides on the fixed cam  78 , and the cam follower  72  is in a lowered position, as shown in  FIG. 8 . In this state, when the chain  23  is driven to move the table  20  until the recessed portion of the V-block  60  comes to over the cam follower  72 , the linear motor mechanism  24  is driven to cause the mobile base  63  to start moving. 
     This moves the cam follower  71  from on the fixed cam  78  onto the movable cam  80 , as shown in  FIG. 9 . Accordingly, the latch lever  68  is pivoted to bring the cam follower  72  into abutment with the recessed portion of the V-block  60 , thereby coupling the cam follower  72  and the V-block  60  to each other. In this state, the table  20  and the movable element  66  of the linear motor mechanism  24  are coupled to each other. When such coupling is achieved, the table  20  is transported by the linear motor mechanism  24 . Thus, the table  20  is transported in one direction with transport accuracy higher than that achieved by the chain  23 . 
     When the mobile base  63  is in a second end position closer to the discharge part  5 , the cam follower  71  is moved from on the movable cam  80  onto the fixed cam  79 , as shown in  FIG. 10 . Accordingly, the latch lever  68  is pivoted to disengage the cam follower  72  from the recessed portion of the V-block  60 , thereby decoupling the cam follower  72  and the V-block  60  from each other. In this state, the table  20  and the movable element  66  of the linear motor mechanism  24  are decoupled from each other. Thereafter, the table  20  is transported again by the chain  23 . 
     In the linear motor mechanism  24 , on the other hand, the mobile base  63  returns from the second end position closer to the discharge part  5  to the first end position closer to the supply part  2 . At this time, an air cylinder  70  is driven to pivot the lock lever  69  about the shaft  73 , as shown in  FIG. 11 . Thus, the latch lever  68  is fixed in a position such that the cam follower  72  is disengaged from the V-block  60 . In this state, the mobile base  63  is moved from the second end position closer to the discharge part  5  to the first end position closer to the supply part  2 . At this time, since the latch lever  68  is fixed in the position where the cam follower  72  is disengaged from the V-block  60 , the cam follower  72  or the like moving in a direction opposite from the direction of travel of the table  20  is prevented from interfering with the V-block  60  or the like. 
     After being transported by the linear motor mechanism  24 , the table  20  is transported again by the chain  23 . The table  20  moves to a predetermined position, and then transfers the recording medium RM held thereon under suction to the discharge part  5 . Thereafter, the table  20  moves on the endless track along the guides  25 , and is used again for the transport of another recording medium RM. 
     As described above, the image recording apparatus  100  sufficiently ensures the accuracy of the holding position of the recording media RM on the tables  20 , and the transport accuracy of the tables  20  during the image recording in the image recording part  4  and during the image reading in the scanner  7 . 
     The image recording apparatus  100  further includes a pre-processing agent ejection head  40  provided upstream from the inkjet heads  4 H in the transport path and for applying a less visible (e.g., transparent) pre-processing agent prior to the ejection of ink from the inkjet heads  4 H for the purpose of enhancing the fixability of ink ejected from the inkjet heads  4 H. The application of such a pre-processing agent is preferable for the image recording especially on recording media RM made of a material poor in ink fixability. 
     The image recording apparatus  100  further includes heaters  45 ,  46 ,  47 ,  48  and  49  provided downstream from the pre-processing agent ejection head  40  and the inkjet heads  4 H, respectively, and for blowing hot air onto the recording media RM. The heater  45  is provided for pre-heating, the heaters  46 ,  47  and  48  are provided for intermediate heating, and the heater  49  is provided for main heating. 
     The pre-processing agent ejection head  40 , the inkjet heads  4 H, the heaters  45  to  49  and the scanner  7  are movable by a drive mechanism not shown in a direction orthogonal to the transport direction of the recording media RM (in a direction perpendicular to the plane of  FIG. 1 ). This enables the pre-processing agent ejection head  40 , the inkjet heads  4 H, the heaters  45  to  49  and the scanner  7  to reciprocatingly move between an image recording position opposed to the transport path of the recording media RM and a maintenance position not opposed to the transport path of the recording media RM. During a maintenance operation, the pre-processing agent ejection head  40 , the inkjet heads  4 H, the heaters  45  to  49  and the scanner  7  are moved to the maintenance position. This removes obstructions on the transport path of the recording media RM to ensure the working space for the maintenance operation of the tables  20  and the like. 
     The discharge part  5  includes a discharge drum  50 . The discharge drum  50  separates the recording media RM from the tables  20  by winding the recording media RM around an outer peripheral portion thereof. 
     In the discharge part  5 , an outlet passage switching mechanism  51  allow selection between the use of a first outlet passage  52  and the use of a second outlet passage  53  in accordance with a switching instruction from the controller  8 . Specifically, each of the first outlet passage  52  and the second outlet passage  53  includes a conveyor. The first outlet passage  52  and the second outlet passage  53  are provided with individual stocking parts (post-recording stocking parts), respectively, for stocking the recording media RM therein. Preferably, the outlet passage switching mechanism  51  operates so that recording media RM subjected to a normal (or proper) image recording process are stocked in the stocking part through the first outlet passage  52 , and other recording media RM are stocked in the stocking part through the second outlet passage  53 . 
     The scanner  7  includes a linear CCD camera, and is adapted to photoelectrically read all or part (a patch and the like) of an image recorded on the recording media RM in response to a reading instruction from the controller  8 . Typically, the scanner  7  reads an image recorded by the image recording part  4 . In some cases, however, the scanner  7  reads an image without the image recording in the image recording part  4 . 
     The display and manipulation part  9  is a display device of a touch panel type. Specifically, with various menus and the like displayed on a screen of the display and manipulation part  9 , an operator touches a predetermined position of the screen to perform an input manipulation. Thus, the display and manipulation part  9  is an integral unit composed of a display part and an input manipulation part as conceptual components. Such a configuration of the display and manipulation part  9  is not essential, but the display and manipulation part  9  may be configured, for example, such that a display part such as a liquid crystal display and an input manipulation part including a plurality of key buttons are provided separately. 
     The recording medium detection sensor  6  is a reflective optical sensor provided downstream from the supply part  2  and upstream from the image recording part  4  over the transport path of the recording media RM, and detects whether there is a recording medium RM on each of the tables  20  or not. The recording medium detection sensor  6  directs light toward a table  20  reaching a position opposed thereto. Also, when there is no recording medium RM on the table  20 , the recording medium detection sensor  6  receives light reflected from the table  20 . When there is a recording medium RM on the table  20 , the recording medium detection sensor  6  receives light reflected from the surface of the recording medium RM. Whether there is a recording medium RM on the table  20  or not is detected based on the amount of reflected light because the amount of reflected light differs depending on whether there is a recording medium RM on the table  20  or not. The recording medium detection sensor  6  is not particularly limited to the reflective optical sensor if the recording medium detection sensor  6  is of the type which is capable of detecting whether there is a recording medium RM on the table  20  or not. 
     &lt;Details of Construction of Controller&gt; 
     Next, the controller  8  provided in the image recording apparatus  100  will be described in detail.  FIG. 12  is a block diagram showing the construction of the controller  8 . 
     The controller  8  includes: a main control part  81  having a CPU  811 , a ROM  812 , a RAM  813  and the like and for effecting centralized control of the operation of the entire image recording apparatus  100  including the image recording process; the supply control part  82  for controlling the operation of the supply part  2 ; a transport control part  83  for controlling the operation of the transport mechanism  3 ; a recording medium detection control part  93  for controlling the operation of the recording medium detection sensor  6 ; an ejection control part  84  for controlling the operation of ejecting ink in the inkjet heads  4 H (and also controlling the ejecting operation of the pre-processing agent ejection head  40  in the image recording apparatus  100 ); a discharge control part  85  for controlling the operation of the discharge part  5 ; a scanner control part  87  for controlling the operation of the scanner  7 ; a display and manipulation control part  89  for controlling the operation of the display and manipulation part  9 ; a malfunctioning linear motor mechanism detection part  90  for detecting a malfunction in the linear motor mechanisms  24 ; an unused linear motor mechanism determination part  91  for determining a linear motor mechanism  24  which is not to be used for the transport of the tables  20 ; and a supply timing determination part  92  for determining whether to provide an intermittent supply when the supply part  2  supplies the recording media RM or not and for determining when to supply the recording media RM during the intermittent supply. 
     The malfunctioning linear motor mechanism detection part  90  detects a malfunction in the linear motor mechanisms  24 . Specifically, when a position detection sensor provided in a linear motor mechanism  24  detects the improper return of the movable element  66  to the first end position of the linear motor mechanism  24  closer to the supply part  2  or when the position of the movable element  66  in the linear motor mechanism  24  is not detected due to a failure of the position detection sensor, the malfunctioning linear motor mechanism detection part  90  detects the linear motor mechanism  24  as a malfunctioning linear motor mechanism. The malfunctioning linear motor mechanism detection part  90  may detect such a malfunction either before the image recording apparatus  100  starts the image recording process or continuously or intermittently while the image recording apparatus  100  performs the image recording process. 
     The unused linear motor mechanism determination part  91  serves to determine a linear motor mechanism  24  which is not to be used for the transport of the tables  20 . In the unused linear motor mechanism determination part  91 , a linear motor mechanism  24  detected as a malfunctioning linear motor mechanism by the malfunctioning linear motor mechanism detection part  90  is determined as the linear motor mechanism  24  which is not to be used for the transport. Additionally, if an operator recognizes a breakage of a linear motor mechanism  24  and the like, the operator may manipulate the display and manipulation part  9  to selectively specify linear motor mechanisms  24  to be used for the transport. Also, the operator may specify whether to stop driving the linear motor mechanism  24  determined as the linear motor mechanism which is not to be used for the transport or not. When the operator determines to stop driving the linear motor mechanism  24 , the driving of the linear motor mechanism  24  is stopped under the control of the transport control part  83 . 
     The supply timing determination part  92  determining whether to provide an intermittent supply such that no recording medium RM is supplied to a specific table  20  when the supply part  2  supplies the recording media RM sequentially to the plurality of tables  20 . When the intermittent supply is to be provided, the supply timing determination part  92  also performs the process of specifying a table  20  to which no recording medium RM is supplied and process of determining a supply timing so that no recording medium RM is supplied to the specific table  20 . The process of determining the supply timing in the supply timing determination part  92  will be described later in detail. The supply control part  82  controls the operation of the supply sucker  13  so that no recording medium RM is attracted under suction, whereby no recording medium RM is supplied to only the specific table  20 . 
     The supply control part  82 , the transport control part  83 , the recording medium detection control part  93 , the ejection control part  84 , the discharge control part  85 , the scanner control part  87 , the display and manipulation control part  89 , the malfunctioning linear motor mechanism detection part  90 , the unused linear motor mechanism determination part  91  and the supply timing determination part  92  may be provided in the form of respective purpose-built control circuits, and may have a CPU, a ROM, a RAM and the like in a manner similar to the main control part  81 . Further, the main control part  81  may also have the functions of the respective control parts. 
     The controller  8  further includes a storage part  86  composed of, for example, a hard disk and the like. The storage part  86  stores therein a program PG executed in the CPU  811  to thereby perform various functions in the main control part  81 , and various data related to the operation of the image recording apparatus  100 . Examples of the data stored in the storage part  86  include image recording data D 0  about descriptions of recording (color density values for respective pixel positions (XY addresses) described based on a CMYK color system) of an image to be recorded, a look-up table TB containing descriptions about a relationship (a tone reproduction curve) between the color density values and the amount of ink ejection for the individual inkjet nozzles, and SPM (screen pattern memory) data DS specifying how to eject ink to form pixels having a given color density value. The image recording data DO may be held in the RAM  813 . 
     &lt;Detailed Description of Transport of Tables by Linear Motor Mechanisms&gt; 
     Next, the transport of the ten tables  20  by using the linear motor mechanisms  24  will be described in detail.  FIGS. 13 to 21  are schematic diagrams of the linear transport section in the image recording apparatus  100  as viewed in the positive Z direction of  FIG. 1  for the purpose of illustrating the transport of the ten tables  20  by using the linear motor mechanisms  24 . The direction of travel of the tables  20  in the linear transport section, i.e. the direction of transport of the recording media RM, is leftward, i.e. from right to left, as viewed in  FIGS. 13 to 21 . 
     With reference to  FIGS. 13 to 21 , reference numerals  24   a ,  24   b ,  24   c ,  24   d  and  24   e  are used to make a distinction between the five linear motor mechanisms  24 , and the linear motor mechanisms  24   a ,  24   b ,  24   c ,  24   d  and  24   e  shall be arranged in the order named in the negative Y direction of  FIG. 1 . Reference numerals  66   a  to  66   e  are used to designate the movable elements of the respective linear motor mechanisms  24   a  to  24   e,  and the movable elements  66   a  to  66   e  are schematically shown in  FIGS. 13 to 21 . Arrows in  FIGS. 13 to 21  denote the direction of the movement of the movable elements  66   a  to  66   e . Reference numerals  20   a  to  20   j  are used to make a distinction between the ten tables  20 . The table  20   a  is the table transported for the first time from a first end position of the linear transport section closer to the supply part  2  (the right-hand end position of the linear motor mechanisms  24   a  to  24   e  as viewed in  FIGS. 13 to 21 ) to a second end position thereof closer to the discharge part  5  (the left-hand end position of the linear motor mechanisms  24   a  to  24   e  as viewed in  FIGS. 13 to 21 ). The tables  20   b,    20   c ,  20   d , . . . and  20   j  are the tables  20  transported following the table  20   a  to the second end position in the order named. Following the table  20   j , the table  20   a  transported by the chain  23  along the endless track after the transport in the linear transport section reaches the first end position of the linear transport section closer to the supply part  2  again. 
       FIGS. 13 to 15  are diagrams for illustration of the transport of the ten tables  20   a  to  20   j  by using the five linear motor mechanisms  24   a  to  24   e . This corresponds to an instance (a first case) in which no linear motor mechanisms  24  are determined by the unused linear motor mechanism determination part  91 . 
     With reference to  FIG. 13 , the tables  20   a ,  20   b  and  20   c  are shown as coupled to the movable elements  66   a ,  66   b  and  66   c , respectively, and transported from right to left as viewed in the figure. The movable element  66   d  is in a standby condition in the first end position of the linear transport section closer to the supply part  2 , pending the table  20   d  to be transported next to the linear transport section by the linear motor mechanisms  24 . The movable element  66   e  is moving, after finishing the transport of the table  20   j  having been executed immediately before the transport of the table  20   a  by the linear motor mechanisms  24 , to return from the second end position of the linear motor mechanism  24   e  closer to the discharge part  5  to the first end position thereof closer to the supply part  2 . 
       FIG. 14  is a diagram showing the linear transport section after the movable element  66   a  finishes the transport of the table  20   a  with reference to  FIG. 13 . The tables  20   b ,  20   c  and  20   d  are shown as coupled to the movable elements  66   b ,  66   c  and  66   d,  respectively, and transported in the order named as viewed from the second end position of the linear transport section closer to the discharge part  5 . The movable element  66   a  is moving to return to the first end position of the linear motor mechanism  24   a  closer to the supply part  2  after finishing the transport of the table  20   a . The movable element  66   e  is in a standby condition in the first end position of the linear motor mechanism  24   e  closer to the supply part  2  pending the table  20   e  to be transported next. 
       FIG. 15  is a diagram showing the linear transport section after the movable element  66   b  finishes the transport of the table  20   b  with reference to  FIG. 14 . The tables  20   c ,  20   d  and  20   e  are shown as coupled to the movable elements  66   c ,  66   d  and  66   e,  respectively, and transported in the order named as viewed from the second end position of the linear transport section closer to the discharge part  5 . The movable element  66   b  is moving to return to the first end position of the linear motor mechanism  24   b  closer to the supply part  2  after finishing the transport of the table  20   b . The movable element  66   a  is in a standby condition in the first end position of the linear motor mechanism  24   a  closer to the supply part  2  pending the table  20   f  to be transported next. 
     In the first case as described above, the five linear motor mechanisms  24   a  to  24   e  are used to transport the tables  20   a  to  20   j  sequentially to the linear transport section. 
       FIGS. 16 to 18  are diagrams for illustration of the transport of the ten tables  20   a  to  20   j  when, because one linear motor mechanism  24   d  included among the five linear motor mechanisms  24   a  to  24   e  malfunctions or for other reasons, the remaining four linear motor mechanisms  24  are used for the transport. In other words,  FIGS. 16 to 18  are diagrams illustrating an instance in which the linear motor mechanism  24   d  is determined to be unused for the transport by the unused linear motor mechanism determination part  91 . This corresponds to an instance (a second case) in which the sum of the number of linear motor mechanisms  24  determined to be unused (in this case, one) and the number of tables transported at the same time (in this case, three) is less than the number of linear motor mechanisms  24  provided in the image recording apparatus  100  (in this case, five). 
     With reference to  FIG. 16 , the tables  20   a ,  20   b  and  20   c  are shown as coupled to the movable elements  66   a ,  66   b  and  66   c , respectively, and transported from right to left as viewed in the figure. The movable element  66   e  is moving, after finishing the transport of the table  20   j  having been executed immediately before the transport of the table  20   a  by the linear motor mechanisms  24 , to return from the second end position of the linear motor mechanism  24   e  closer to the discharge part  5  to the first end position thereof closer to the supply part  2 . The movable element  66   d  (and the linear motor mechanism  24   d ) is not used for the transport, as mentioned above. 
       FIG. 17  is a diagram showing the linear transport section after the movable element  66   a  finishes the transport of the table  20   a  with reference to  FIG. 16 . The tables  20   b  and  20   c  are shown as coupled to the movable elements  66   b  and  66   c , respectively, and transported in the order named as viewed from the second end position of the linear transport section closer to the discharge part  5 . Since the linear motor mechanism  24   d  is determined to be unused by the unused linear motor mechanism determination part  91 , the table  20   d  is coupled to the movable element  66   e  provided in the linear motor mechanism  24   e  and transported thereby. The movable element  66   a  is moving to return to the first end position of the linear motor mechanism  24   a  closer to the supply part  2  after finishing the transport of the table  20   a.    
       FIG. 18  is a diagram showing the linear transport section after the movable element  66   b  finishes the transport of the table  20   b  with reference to  FIG. 17 . The tables  20   c ,  20   d  and  20   e  are shown as coupled to the movable elements  66   c ,  66   e  and  66   a,  respectively, and transported in the order named as viewed from the second end position of the linear transport section closer to the discharge part  5 . The movable element  66   b  is moving to return to the first end position of the linear motor mechanism  24   b  closer to the supply part  2  after finishing the transport of the table  20   b.    
     As described above, the second case provides a throughput similar to that of the first case to achieve the image recording although the linear motor mechanism  24  determined to be unused is present. 
       FIGS. 19 to 21  are diagrams for illustration of the transport of the ten tables  20   a  to  20   j  when, because two linear motor mechanisms  24   c  and  24   d  included among the five linear motor mechanisms  24   a  to  24   e  malfunction or for other reasons, the remaining three linear motor mechanisms  24  are used for the transport. In other words,  FIGS. 19 to 21  are diagrams illustrating an instance in which the linear motor mechanisms  24   c  and  24   d  are determined to be unused for the transport by the unused linear motor mechanism determination part  91 . This corresponds to an instance (a third case) in which the sum of the number of linear motor mechanisms  24  determined to be unused (in this case, two) and the number of tables transported at the same time (in this case, three) is equal to the number of linear motor mechanisms  24  provided in the image recording apparatus  100  (in this case, five). 
     With reference to  FIG. 19 , the tables  20   a ,  20   b  and  20   c  are shown as coupled to the movable elements  66   a ,  66   b  and  66   e , respectively, and transported from right to left as viewed in the figure. The movable element  66   c  (and the linear motor mechanism  24   c ) and the movable element  66   d  (and the linear motor mechanism  24   d ) are not used for the transport, as mentioned above. In the case shown in  FIG. 19 , there is neither movable element  66  moving to return nor movable element  66  in a standby condition. 
       FIG. 20  is a diagram showing the linear transport section after the movable element  66   a  finishes the transport of the table  20   a  with reference to  FIG. 19 . The tables  20   b  and  20   c  are shown as coupled to the movable elements  66   b  and  66   e , respectively, and transported in the order named as viewed from the second end position of the linear transport section closer to the discharge part  5 . The movable element  66   a  is moving to return to the first end position of the linear motor mechanism  24   a  closer to the supply part  2  after finishing the transport of the table  20   a . Thus, at this point, there is no linear motor mechanism  24  that is able to transport the table  20   d . In such a case, the chain  23  is used in place of the linear motor mechanisms  24  to transport the table  20   d  in this preferred embodiment. Thus, the chain  23  is used as an alternative to transport a table  20  which cannot be transported by the linear motor mechanisms  24  in the linear transport section because of the presence of the linear motor mechanism  24  determined to be unused. 
       FIG. 21  is a diagram showing the linear transport section after the movable element  66   b  finishes the transport of the table  20   b  with reference to  FIG. 20 . The tables  20   c  and  20   e  are shown as coupled to the movable elements  66   e  and  66   a , respectively, and transported in the order named as viewed from the second end position of the linear transport section closer to the discharge part  5 . The table  20   d  is shown as transported by the chain  23 . The movable element  66   b  is moving to return to the first end position of the linear motor mechanism  24   b  closer to the supply part  2  after finishing the transport of the table  20   b.    
     In the third case as described above, one of the tables  20  is required to be transported before any of the movable elements  66  returns. In such a case, this table  20  is not transported by the linear motor mechanisms  24 , but the chain  23  is used as an alternative to transport this table  20 . 
     By way of amplification of the first to third cases described above, the image recording apparatus  100  according to this preferred embodiment is adapted to transport the table  20  in a manner to be described below. When the sum (x+y) of the number (x) of linear motor mechanisms  24  determined to be unused and the number (y) of tables  20  transported at the same time in the linear transport section is less than the number (z) of linear motor mechanisms  24  provided in the image recording apparatus  100 , the linear motor mechanisms  24  except the linear motor mechanism(s)  24  determined to be unused are used to transport the tables  20 . When the above-mentioned sum (x+y) is not less than the number (z) of linear motor mechanisms  24  provided in the image recording apparatus  100 , the chain  23  is used as an alternative for the transport. 
     This prevents the entire image recording apparatus  100  from becoming immediately unusable if there is a linear motor mechanism determined to be unused because of a breakage, an operation anomaly and the like, to allow the continuous image recording although the throughput thereof decreases. Thus, this preferred embodiment suppresses the reduction in productivity, as compared with the complete stop of the image recording apparatus  100 . 
     From another point of view, setting the number (z) of linear motor mechanisms  24  provided in the image recording apparatus  100  greater by two than the number (y) of tables  20  transported at the same time in the linear transport section eliminates the need to use the chain  23  as an alternative for the transport until the above-mentioned sum (x+y) becomes equal to the number (z) of linear motor mechanisms  24  provided in the image recording apparatus  100  if there is a linear motor mechanism  24  determined to be unused. 
     &lt;Supply Timing of Recording Media RM&gt; 
     Next, the supply timing of the recording media RM from the supply part  2  will be described in detail. For example, when there is a table  20  which cannot be transported by the linear motor mechanisms  24  but is required to be transported by the chain  23  in the linear transport section as in the third case mentioned above, the image recording on a recording medium RM transported by this table  20  provides insufficient image recording accuracy. Thus, the image recording apparatus  100  is adapted so that no recording medium RM is supplied from the supply part  2  to the table  20  transported by the chain  23  as an alternative. In other words, the intermittent supply of the recording media RM is provided. 
       FIG. 22  is a flow diagram showing the process of determining the supply timing of the recording media RM, i.e. when to supply the recording media RM, from the supply part  2 . First, the unused linear motor mechanism determination part  91  determines a linear motor mechanism  24  to be unused for the transport (in Step S 1 ). As mentioned above, the linear motor mechanism  24  determined to be unused includes a linear motor mechanism  24  specified arbitrarily by an operator in addition to a linear motor mechanism  24  detected by the malfunctioning linear motor mechanism detection part  90  as a malfunctioning linear motor mechanism. 
     Subsequently, linear setting data D about descriptions of information indicating whether each of the linear motor mechanisms  24   a  to  24   e  is to be used for the transport or not is generated in the unused linear motor mechanism determination part  91  (in Step S 2 ). Specifically, the linear setting data D is 5-bit data composed of five 1-bit data Da, Db, Dc, Dd and De each taking a value of “0” or “1” and indicated in the form of D=(Da, Db, Dc, Dd, De). 
     The 1-bit data Da to De are those corresponding to the linear motor mechanisms  24   a  to  24   e , respectively. When each of the linear motor mechanisms  24  is determined to be unused, the value of the corresponding 1-bit data is “0.” When each of the linear motor mechanisms  24  is determined to be used, the value of the corresponding 1-bit data is “1.” Alternatively, the value of the corresponding 1-bit data may be “0” when each of the linear motor mechanisms  24  is determined to be used, and be “1” when each of the linear motor mechanisms  24  is determined to be unused. 
     For example, when all of the five linear motor mechanisms  24  are to be used (in corresponding relation to the first case), D=(1, 1, 1, 1, 1). When only the linear motor mechanism  24   d  is registered as a linear motor mechanism to be unused because of a malfunction and the like (in corresponding relation to the second case), D=(1, 1, 1, 0, 1). When the linear motor mechanism  24   c  and  24   d  are registered as linear motor mechanisms to be unused (in corresponding relation to the third case), the 5-bit data D=(1, 1, 0, 0, 1) is generated. 
     Next, whether to provide the intermittent supply or not is judged in the supply timing determination part  92 , based on the linear setting data D (in Step S 3 ). Whether to provide the intermittent supply or not is determined by whether there is a table  20  to be transported by the chain  23  or not. Specifically, when x+y≧z, it is judged to be necessary to provide the intermittent supply, and the process in Step S 4  is subsequently performed. When x+y&lt;z in the linear transport section, it is not judged to be necessary to provide the intermittent supply, and the process in Step S 6  is subsequently performed. 
     When it is judged to be necessary to provide the intermittent supply, the supply timing determination part  92  determines the supply timing of the recording media RM so as to provide the intermittent supply (in Step S 4 ). Specifically, when the ten tables  20  to be sequentially transported are to be transported by the chain  23  as an alternative is determined in accordance with the information described in the linear setting data D and specifying the use or non-use of the linear motor mechanisms  24   a  to  24   e . In accordance with such a corresponding relationship, a determination is made as to whether the supply part  2  supplies a recording medium RM to each of the tables  20  or not (i.e., whether the supply part  2  provides the intermittent supply or not). 
       FIG. 23  is a view for illustration of the supply timing of the recording media RM which is determined by the supply timing determination part  92  when the linear motor mechanisms  24   c  and  24   d  are to be unused (in corresponding relation to the third case). A corresponding relationship between the tables  20   a  to  20   j  and the linear motor mechanisms  24   a  to  24   e  (i.e., the movable elements  66   a  to  66   e ) for transporting the tables  20   a  to  20   j  is shown in  FIG. 23 . 
     In  FIG. 23  are shown the liner motor mechanisms  24   a  to  24   e  or the chain  23  responsible for the transport of the tables  20   a  to  20   j  in the linear transport section. The tables  20  transported by the chain  23  are diagonally shaded in  FIG. 23 . When the linear motor mechanism  24  to be unused is not determined, the table  20   a ,  20   b ,  20   c ,  20   d ,  20   e,    20   f , . . . (repeated) shall be transported sequentially by the linear motor mechanisms  24   a,    24   b ,  24   c ,  24   d ,  24   e ,  24   a , . . . (repeated). In other words, the order in which the tables  20   a  to  20   j  are transported in the linear transport section is shown from the upper left in  FIG. 23 . 
     In the third case where D=(1, 1, 0, 0, 1), the table  20   a  is initially transported by the movable element  66   a  of the linear motor mechanism  24   a , and the tables  20   b  is then transported by the movable element  66   b  of the linear motor mechanism  24   b , as sequentially shown in  FIGS. 19 to 21 . The table  20   c  to be transported next is transported by the movable element  66   e  of the linear motor mechanism  24   e  because the originally scheduled linear motor mechanism  24   c  and also the linear motor mechanism  24   d  are to be unused. 
     Subsequently, the table  20   d  is transported to the first end position of the linear transport section closer to the supply part  2  and serves as the next table to be transported in the linear transport section. At this point, however, there is no linear motor mechanism  24  which can transport the table  20   d . Thus, the table  20   d  is transported by the chain  23 . 
     Thereafter, the tables  20   e ,  20   f  and  20   g  are transported by using the linear motor mechanisms  24   a ,  24   b  and  24   e , respectively, and the table  20   h  is transported by the chain  23  in a similar manner. Further, the tables  20   i ,  20   j  and  20   a  are transported by using the linear motor mechanisms  24   a ,  24   b  and  24   e , respectively, and the table  20   b  is transported by the chain  23 . 
     In the third case where D=(1, 1, 0, 0, 1) as described above, three tables  20  are transported by the linear motor mechanisms  24   a ,  24   b ,  24   e , and subsequently one table is transported by the chain  23 . In other words, every fourth table  20  starting with the table  20   d  is transported by the chain  23  as an alternative. In such a case, the supply timing determination part  92  determines the supply timing of the recording media RM from the supply part  2  so that no recording medium RM is supplied to every fourth table  20  as mentioned above. During the image recording, the supply control part  82  controls the supply part  2  so that the supply part  2  supplies the recording media RM to the tables  20  in accordance with such supply timing. 
     Next, the recording medium detection control part  93  makes setting so as to exclude a table  20  to which no recording medium RM is supplied because of the transport by the chain  23  as an alternative from the tables  20  to be detected by the recording medium detection sensor  6  (in Step S 5 ). This intentionally excludes the table  20  to which no recording medium RM is supplied and which is transported by the chain  23  as an alternative from the tables  20  to be subjected to the error detection in the recording medium detection sensor  6  in the image recording apparatus  100 . 
     After the processes in Steps S 1  to S 5  are completed, the image recording is performed (in Step S 6 ). Specifically, the transport control part  83  places the transport mechanism  3  in operation. Also, the supply part  2  supplies the recording media RM to the tables  20  under the control of the supply control part  82 , and the inkjet heads  4 H eject ink under the control of the ejection control part  84 , whereby the image recording is achieved. More specifically, when the intermittent supply of the recording media RM is not provided, the recording media RM are transported to all of the tables  20 . On the other hand, when the intermittent supply of the recording media RM is provided, the intermittent supply is provided in accordance with the supply timing determined in Step S 4 . At the time that the table  20  to be transported by the chain  23  as an alternative is transported in the linear transport section when the intermittent supply is provided, the supply control part  82  effects control so that the supply sucker  13  attracts under suction no recording medium RM placed on or stocked in the pre-recording stocking part  10 . 
     As described hereinabove, the image recording apparatus  100  according to this preferred embodiment is capable of determining at least one of the linear motor mechanisms  24  to be unused for the transport to record an image without using the determined linear motor mechanism  24 . Additionally, when the sum of the number of linear motor mechanisms  24  determined to be unused and the number of tables  20  transported at the same time in the linear transport section is less than the number of linear motor mechanisms  24  provided in the image recording apparatus  100 , the linear motor mechanisms  24  except the linear motor mechanism  24  determined to be unused are used to transport the tables  20 . When the above-mentioned sum is not less than the number of linear motor mechanisms  24  provided in the image recording apparatus  100 , the chain  23  is used as an alternative for the transport. Thus, if a malfunctioning linear motor mechanism  24  is present because of a breakage, an operation anomaly and the like, the image recording apparatus  100  is capable of achieving the image recording although the throughput thereof decreases, to thereby suppress the reduction in productivity, as compared with the complete stop of the image recording apparatus  100 . 
     Additionally, the supply part  2  is configured to supply no recording medium RM to the table  20  which cannot be transported by the linear motor mechanisms  24  but is required to be transported by the chain  23  as an alternative in the linear transport section. Thus, if at least one of the linear motor mechanisms  24  cannot be used for the transport because of a breakage, a malfunction and the like, the image recording apparatus  100  is capable of maintaining the accuracy of image recording as high as that obtained when there is no linear motor mechanism  24  determined to be unused. 
     &lt;Modifications&gt; 
     Although the image recording apparatus  100  is described as an inkjet printer in the above-mentioned preferred embodiment, the application of the present invention is not limited to an apparatus for recording an image based on inkjet technology. 
     Although the transport mechanism  3  includes the ten tables  20  in the above description, the number of tables  20  provided in the transport mechanism  3  is not limited to ten. 
     Although the transport mechanism  3  includes the five linear motor mechanisms  24  in the above description, the number of linear motor mechanisms  24  provided in the transport mechanism  3  is not limited to five. 
     The order in which the plurality of linear motor mechanisms  24  are used to transport the tables  20  is not limited to that shown in  FIGS. 13 to 21 . 
     Although the linear motor mechanisms  24  are capable of transporting a maximum of three tables  20  at the same time in the above description, the maximum number of tables  20  transported by the linear motor mechanisms  24  at the same time is not limited to three. 
     While the invention has been described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is understood that numerous other modifications and variations can be devised without departing from the scope of the invention.