Patent Publication Number: US-10328728-B2

Title: Image recording apparatus and image recording method for printing each of a plurality of unit images

Description:
RELATED APPLICATIONS 
     This application is the U.S. National Phase under 35 U.S.C. § 371 of International Application No. PCT/JP2015/085461, filed on Dec. 18, 2015, which in turn claims the benefit of Japanese Application No. 2015-022816, filed on Feb. 9, 2015, the disclosures of which are incorporated by reference herein. 
     TECHNICAL FIELD 
     The present invention relates to an image recording apparatus and an image recording method. 
     BACKGROUND ART 
     An image recording apparatus for recording images on an elongated strip-shaped recording medium and what is called a post-processing machine for processing the elongated strip-shaped recording medium on which images are recorded by the image recording apparatus have heretofore been known. In such an image recording apparatus, multiple independent images are sequentially printed in a longitudinal direction of the recording medium. Examples of the post-processing machine include another image recording apparatus for recording images on the back surface of the recording medium, a cutting apparatus for cutting the recording medium, a folding apparatus for folding the recording medium, and an half-cutting apparatus for cutting only a sticker layer of the recording medium comprised of a backing layer and the sticker layer. 
     Such a conventional image recording apparatus and such a conventional post-processing machine are disclosed in Japanese Patent Application Laid-Open No. 2002-46260, for example. An inkjet printer disclosed in Japanese Patent Application Laid-Open No. 2002-46260 includes an image recording part for recording images on elongated strip-shaped recording paper, and a cutting part for cutting the recording paper on which images are recorded (in paragraph 0011, and FIG. 1). 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: Japanese Patent Application Laid-Open No. 2002-46260 
     SUMMARY OF INVENTION 
     Technical Problem 
     Some elongated strip-shaped recording media are formed by joining a plurality of recording media together in a longitudinal direction thereof. Such an elongated strip-shaped recording medium has a splice part in which an upstream recording medium and a downstream recording medium are connected to each other with an adhesive agent, an adhesive tape or the like. The splice part is thicker than other parts of the recording medium. For this reason, there is apprehension that the splice part comes in contact with a recording head when the splice part passes near the recording head without changing the relative position of the recording head and the recording medium from that during printing. 
     For restraining contact between the splice part and the recording head, it is necessary that the step of printing by means of the recording head is suspended during the passage of the splice part near the recording head and that the relative position of the recording head and the recording medium is changed to a retracted position in which the splice part and the recording head are out of contact with each other. 
     However, the suspension of the printing poses a danger that the period of the recording positions of images on the recording medium after the restart of the printing does not coincide with the period of the recording positions of images before the suspension of the printing. If such a difference exists between the periods of the recording positions of the images before the suspension of the printing and after the restart of the printing, there arises a need to set a processing period again in the post-processing machine in accordance with the period of the recording positions of images recorded after the restart of the printing. 
     In view of the foregoing, it is an object of the present invention to provide a technique capable of restraining a difference between the periods of image recording positions before and after the suspension of the step of printing in an image recording apparatus for recording images on an elongated strip-shaped recording medium. 
     Solution to Problem 
     To solve the aforementioned problem, a first aspect of the present invention is intended for an image recording apparatus for printing each of a plurality of unit images for each predetermined printing period on an elongated strip-shaped recording medium while transporting the recording medium. The image recording apparatus comprises: a transport part for transporting the recording medium along a transport path; a recording head for ejecting droplets onto the recording medium disposed in a recording region on the transport path to print an image on the recording medium; a detector disposed upstream of the recording head and for detecting a thick part of the recording medium, the thick part being thicker than other parts of the recording medium; a relative position switching part for switching the relative position of the recording head and the recording region to a printing position and to a retracted position; a storage part for storing a last start position that is a start position of the last one of the unit images on the recording medium; and a controller for controlling the parts, the controller stopping the printing by means of the recording head and switching the relative position of the recording head and the recording region to the retracted position by means of the relative position switching part before the thick part reaches the recording region, the controller switching the relative position of the recording head and the recording region to the printing position by means of the relative position switching part and starting the printing of a new one of the unit images by means of the recording head from a position an integral multiple of the printing period apart from the last start position after the thick part passes through the recording region. 
     According to a second aspect of the present invention, in the image recording apparatus of the first aspect, the controller stops the printing by means of the recording head after one of the unit images being printed when the detector detects the thick part is printed completely to the end. 
     According to a third aspect of the present invention, in the image recording apparatus of the first or second aspect, the storage part stores therein a virtual last start position while the printing by means of the recording head is stopped, the virtual last start position becoming the last start position on the recording medium if the printing continues; and the controller restarts the printing of the unit images by means of the recording head from the position an integral multiple of the printing period apart from the last start position, based on the virtual last start position, when starting the printing of the new one of the unit images after the printing is stopped. 
     According to a fourth aspect of the present invention, in the image recording apparatus of any one of the first to third aspects, the controller makes the transport speed of the recording medium by means of the transport part lower than that during the printing and switches the relative position of the recording head and the recording region to the retracted position by means of the relative position switching part before the thick part reaches the recording region and after the printing by means of the recording head is stopped. 
     According to a fifth aspect of the present invention, in the image recording apparatus of any one of the first to fourth aspects, the controller switches the relative position of the recording head and the recording region to the printing position by means of the relative position switching part while the transport of the recording medium by means of the transport part is stopped after the thick part passes through the recording region. 
     According to a sixth aspect of the present invention, in the image recording apparatus of any one of the first to fifth aspects, the relative position switching part moves the recording head to thereby switch the relative position of the recording head and the recording region. 
     According to a seventh aspect of the present invention, in the image recording apparatus of any one of the first to fifth aspects, the transport part includes a plurality of platen rollers extending in a substantially horizontal direction orthogonal to the transport path and constituting the recording region; and the relative position switching part moves the platen rollers to thereby switch the relative position of the recording head and the recording region. 
     An eighth aspect of the present invention is intended for a method of recording an image, the method printing each of a plurality of unit images for each predetermined printing period by ejecting droplets from a recording head onto an elongated strip-shaped recording medium disposed in a recording region on an transport path while transporting the recording medium along the transport path. The method comprises the steps of: a) storing a last start position that is a start position of the last one of the unit images on the recording medium; b) detecting a thick part of the recording medium in a position upstream of the recording region, the thick part being thicker than other parts of the recording medium, the step b) being performed after the step a); c) stopping the printing by means of the recording head, the step c) being performed after the step b); d) switching the relative position of the recording head and the recording region from a printing position to a retracted position, the step d) being performed after the step c); e) switching the relative position of the recording head and the recording region from the retracted position to the printing position, the step e) being performed after the step d) and after the thick part passes through the recording region; and f) printing a new one of the unit images from a position an integral multiple of the printing period apart from the last start position, the step f) being performed after the step e). 
     According to a ninth aspect of the present invention, in the method of the eighth aspect, if one of the unit images is being printed when the thick part is detected in the step b), the one unit image being printed when the thick part is detected is printed completely to the end before the step c). 
     According to a tenth aspect of the present invention, in the method of the eighth or ninth aspect, in the step d), the transport speed of the recording medium is made lower than that during the printing, and the relative position of the recording head and the recording region is switched from the printing position to the retracted position. 
     According to an eleventh aspect of the present invention, in the method of any one of the eighth to tenth aspects, in the step e), the relative position of the recording head and the recording region is switched from the retracted position to the printing position while the transport of the recording medium is stopped. 
     Advantageous Effects of Invention 
     According to the first to tenth aspects of the present invention, in the image recording apparatus for recording an image on the elongated strip-shaped recording medium, a difference between the periods of image recording positions before and after the suspension of a printing step is restrained while the thick part of the recording medium is restrained from coming in contact with the recording head. 
     In particular, according to the second to fifth aspects and the ninth to eleventh aspects of the present invention, waste of the recording medium is reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a view conceptually showing the configuration of a printing apparatus according to one embodiment. 
         FIG. 2  is a block diagram showing a control system for the printing apparatus according to the one embodiment. 
         FIG. 3  is a flow diagram showing a procedure for a printing suspension step according to the one embodiment. 
         FIG. 4  is a view showing an example of printing paper according to the one embodiment. 
         FIG. 5  is a flow diagram showing a procedure for a remaining job count calculation step according to the one embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment according to the present invention will now be described with reference to the drawings. A direction in which printing paper is transported is referred to as a “transport direction”, and a horizontal direction orthogonal to the transport direction is referred to as a “width direction” hereinafter. 
     &lt;1. Configuration of Printing Apparatus&gt; 
       FIG. 1  is a view conceptually showing the configuration of a printing apparatus  1  according to one embodiment of the present invention.  FIG. 2  is a block diagram showing a control system for the printing apparatus  1 . This printing apparatus  1  is an inkjet printing apparatus which records color images on printing paper  9  that is an elongated strip-shaped recording medium by ejecting ink droplets from a plurality of recording heads  30  onto the printing paper  9  while transporting the printing paper  9 . 
     This printing apparatus  1  prints each of a plurality of unit images for each predetermined printing period (predetermined distance) on the printing paper  9 . The printing paper  9  on which the unit images are printed in the printing apparatus  1  is cut for each printing period or is creased near a boundary between the printing periods, for example, in a post-processing machine such as a cutting machine, a folding machine or the like. 
     As shown in  FIG. 1 , the printing apparatus  1  includes a transport mechanism  20 , four recording heads  30 , head moving mechanisms  31 , a splice detector  40 , a UV lamp  50  and a controller  10 . 
     The transport mechanism  20  is a mechanism for transporting the printing paper  9  in the transport direction that is the longitudinal direction of the printing paper  9  while holding the printing paper  9 . The transport mechanism  20  according to the present embodiment includes an unwinder  21 , a plurality of transport rollers  22 , two drive rollers  23  and a winder  24 . 
     A motor  25  serving as a power source is coupled to the two drive rollers  23  and the winder  24  via belts. For controlling tension, the unwinder  21  is coupled to a brake (not shown). The drive rollers  23  and the winder  24  rotate when the controller  10  drives the motor  25 . All of the transport rollers  22  according to the present embodiment are follower rollers which are not coupled to the motor  25  but rotate in accordance with the motion of the printing paper  9 . At least one of the transport rollers  22  may be a drive roller coupled to the motor  25 . 
     The transport rollers  22  constitute a transport path for the printing paper  9 . Each of the transport rollers  22  rotates about a horizontal axis to guide the printing paper  9  downstream along the transport path. The printing paper  9  comes in contact with the transport rollers  22 , so that tension is applied to the printing paper  9 . In this manner, the printing paper  9  is unwound from the unwinder  21 , and is transported along the transport path formed by the transport rollers  22  to the winder  24 . After being transported, the printing paper  9  is wound and collected on the winder  24 . 
     The transport rollers  22  include encoder rollers  221  and platen rollers  222 . The encoder rollers  221  detect the transport speed and transport distance of the printing paper  9 . The platen rollers  222  in positions opposed to the recording heads  30  support the printing paper  9 . A region included in the transport path of the printing paper  9  and supported by the platen rollers  222  serves as an image recording region Rp. The positions of the platen rollers  222  constituting the recording region Rp are fixed in the present embodiment. 
     The four recording heads  30  are arranged in spaced apart relation in the transport direction over the transport path of the printing paper  9 . The four recording heads  30  eject ink droplets of cyan (C), magenta (M), yellow (Y) and black (K), respectively, onto the upper surface of the printing paper  9  passing through the recording region Rp on the transport path. 
     The printing apparatus  1  according to the present embodiment is what is called a one-pass type recording apparatus which records a desired image pattern on the printing paper  9  by ejecting ink droplets from the recording heads  30  while the printing paper  9  passes under the recording heads  30  only once. 
     The lower surface of each of the recording heads  30  has a plurality of nozzles disposed in a two-dimensional array. The positions of the individual nozzles are shifted in the width direction, and each of the nozzles is assigned to a region having a width of one pixel on the printing paper  9 . 
     The head moving mechanisms  31  are mechanisms for moving the positions of the respective recording heads  30  to a printing position and to a retracted position. During printing, the head moving mechanisms  31  place the respective recording heads  30  in the printing position in which the distance between the lower surfaces of the respective recording heads  30  and the printing paper  9  having an ordinary thickness and placed on the recording region Rp is 1 mm, for example. 
     During retraction, the head moving mechanisms  31  place the respective recording heads  30  in the retracted position in which the distance between the lower surfaces of the respective recording heads  30  and the printing paper  9  having the ordinary thickness and placed on the recording region Rp is 5 mm, for example. In this manner, the head moving mechanisms  31  constitute a relative position switching part for switching the relative position of the recording heads  30  and the recording region Rp to the printing position and to the retracted position. 
     Although the head moving mechanisms  31  are conceptually shown in  FIG. 1 , a variety of known mechanisms may be used to implement the head moving mechanisms  31 . Specifically, a mechanism which moves the recording heads  30  upwardly and downwardly along a ball screw by rotating the ball screw with the power of a motor, for example, may be used. 
     The splice detector  40  is disposed upstream of the recording heads  30  and detects a splice part of the printing paper  9 . The printing paper  9  is formed by joining a plurality of printing paper sheets together in a longitudinal direction thereof. For this reason, the printing paper  9  has a splice part in which an upstream printing paper sheet and a downstream printing paper sheet are connected to each other with an adhesive agent or an adhesive tape. That is, the splice part is a thick part thicker than other parts of the printing paper  9 . 
     An ultrasonic sensor for sensing different values depending on the thickness and material of the printing paper  9  is used for the splice detector  40  according to the present embodiment. Thickness detecting devices other than the ultrasonic sensor may be used for the splice detector  40 . 
     The UV lamp  50  is disposed downstream of the recording heads  30  and irradiates a printing surface of the printing paper  9  with ultraviolet light. Inks used in the present embodiment are UV curable inks. After the ejection of the inks onto the printing paper  9  in the recording region Rp, the irradiation of the corresponding part of the printing paper  9  with the ultraviolet light from the UV lamp  50  cures the inks to fix the inks on the printing paper  9 . 
     The controller  10  controls the operations of the parts of the printing apparatus  1 . As conceptually shown in  FIG. 1 , the controller  10  according to the present embodiment is formed by a computer including an arithmetic processor  11  such as a CPU, a memory  12  such as a RAM and a storage part  13  such as a hard disk drive. As shown in  FIG. 2 , the controller  10  is electrically connected to the encoder rollers  221  and the motor  25  in the transport mechanism  20 , the recording heads  30 , the head moving mechanisms  31 , the splice detector  40  and the UV lamp  50 . 
     The controller  10  temporarily reads a computer program  131  and data  132  which are stored in the storage part  13  onto the memory  12 . The controller  10  causes the arithmetic processor  11  to perform arithmetic processing based on the computer program  131  and the data  132  which are temporarily read, thereby controlling the operations of the parts of the printing apparatus  1 . Thus, a printing step in the printing apparatus  1  proceeds. The controller  10  may be formed by electronic circuitry. 
     &lt;2. Suspension of Printing Step During Passage of Splice Part&gt; 
     Next, the suspension of the printing step in the printing apparatus  1  at the time of the detection of a splice part will be described with reference to  FIGS. 3 to 5 .  FIG. 3  is a flow diagram showing a procedure for the suspension of the printing step at the time of the detection of a splice part according to the present embodiment.  FIG. 4  is a view showing an example of the printing paper  9  after the end of the printing.  FIG. 5  is a flow diagram showing a procedure for a remaining job count calculation step. 
     During the printing step in the printing apparatus  1 , the recording heads  30  are placed in the printing position. Specifically, the distance between the lower surfaces of the recording heads  30  and the printing paper  9  having an ordinary thickness and placed on the recording region Rp is 1 mm, for example. For this reason, there is apprehension that a splice part  90  comes in contact with the lower surfaces of the recording heads  30  if the splice part  90  of the printing paper  9  passes under the recording heads  30  while the recording heads  30  remain placed in the printing position. The contact of the splice part  90  with the lower surfaces of the recording heads  30  might cause an ejection failure and a malfunction in the recording heads  30 . 
     To prevent the ejection failure and the malfunction, this printing apparatus  1  suspends the printing step when the splice detector  40  detects the splice part  90 .  FIG. 3  shows a specific procedure therefor. After starting the printing step, the controller  10  judges whether the splice detector  40  has detected the splice part  90  or not (Step S 101 ). If the splice detector  40  has not detected the splice part  90  in Step S 101 , the procedure returns to Step S 101 , and the controller  10  continues the printing step while monitoring whether the splice detector  40  has detected the splice part  90  or not. 
     During the execution of the printing step, a start position marker  91  and a unit image  92  are printed for each printing period T on the printing paper  9 , as shown in  FIG. 4 . 
     The start position marker  91  is printed for ease of identification of the start position of each printing period T during the processing in the post-processing machine. Although the start position marker  91  is printed for each printing period T in the present embodiment, the present invention is not limited to this. The start position marker  91  need not be printed on the printing paper  9  or may be printed for only the printing period T including the most upstream unit image  92 . Alternatively, a marker indicating the end position or the middle position of each printing period may be printed in place of the start position marker  91 . 
     During the execution of the printing step, the controller  10  stores a last start position that is the start position of the last unit image  92  on the printing paper  9  at that point of time in the storage part  13  of the controller  10 . That is, the storage part  13  has the last start position stored therein in the present embodiment. However, the last start position may be stored in the memory  12  of the controller  10 . 
     Each time the printing of a new unit image  92  starts, the controller  10  updates the last start position stored in the storage part  13  to the start position of a new image period. The last start position P 1  before the suspension of the printing step is shown in  FIG. 4 . 
     If the splice detector  40  has detected the splice part  90  in Step S 101 , the procedure proceeds to Step S 102 . Then, the controller  10  calculates a remaining job count N before suspension indicative of the number of unit images  92  recordable on the printing paper  9  during a time interval between that point of time and the suspension of the printing step, and an on-movement transport speed V′ indicative of the transport speed of the printing paper  9  at the time of suspension of the printing (Step S 102 ). A specific method of the calculation in Step S 102  will be described later. 
     The calculation of the aforementioned values in Step S 102  may be performed before the start of the printing on the printing paper  9 . Specifically, the step of calculating the aforementioned values which corresponds to Step S 102  may be previously performed after job data is inputted from outside to the controller  10  and before the printing on the printing paper  9  starts. 
     Subsequent to Step S 102 , the printing apparatus  1  performs the printing of remaining jobs (Step S 103 ). Specifically, if it is judged in Step S 102  that the remaining job count N before suspension is equal to 0 and if any unit image  92  is being printed, the printing is promptly stopped. If it is judged in Step S 102  that the remaining job count N before suspension is equal to 1, the unit image  92  being printed at the time of detection of the splice part  90  is printed completely to the end, but a new unit image  92  is not printed. If it is judged in Step S 102  that the remaining job count N before suspension is not less than 2, the unit image  92  being printed at the time of detection of the splice part  90  is printed completely to the end, and at least one unit image  92  corresponding to (N−1) period(s) is printed, following which the printing is stopped. 
     If the on-movement transport speed V′ calculated in Step S 102  differs from an ordinary on-printing transport speed V after the printing by means of the recording heads  30  is stopped, the transport speed of the printing paper  9  by means of the transport mechanism  20  is changed to the on-movement transport speed V′. Thus, the transport speed of the printing paper  9  is made lower than that during the printing. Then, the head moving mechanisms  31  are put into operation to shift the recording heads  30  from the printing position to the retracted position (Step S 104 ). 
     Setting the remaining job count N and the on-movement transport speed V′ to suitable values in Step S 102  restrains the splice part  90  from reaching the recording region Rp before the completion of the movement of the recording heads  30  in Step S 104 . This restrains the splice part  90  from coming in contact with the recording heads  30 . 
     After the completion of Step S 104 , the controller  10  changes the transport speed of the printing paper  9  by means of the transport mechanism  20  back to the on-printing transport speed V. Then, the controller  10  judges whether the splice part  90  has reached a predetermined retraction end position Ps or not, based on the position in which the splice detector  40  has detected the splice part  90  and the transport distance of the printing paper  9  inputted from the encoder rollers  221  (Step S 105 ). 
     The retraction end position Ps in the present embodiment is downstream of the recording heads  30  and upstream of the UV lamp  50 . Thus, whether the splice part  90  has reached a position downstream of the recording heads  30  or not is judged in Step S 105 . It is only necessary that the retraction end position Ps is downstream of at least the recording heads  30 . The retraction end position Ps may be downstream of the UV lamp  50 . 
     If the controller  10  judges that the splice part  90  has not reached the retraction end position Ps in Step S 105 , the procedure returns to Step S 105 , and the controller  10  goes on standby. 
     On the other hand, if the controller  10  judges that the splice part  90  has reached the retraction end position Ps in Step S 105 , the controller  10  puts the head moving mechanisms  31  into operation again to shift the recording heads  30  from the retracted position to the printing position (Step S 106 ). 
     In Step S 106 , the controller  10  may move the recording heads  30  from the retracted position to the printing position while the transport of the printing paper  9  by means of the transport mechanism  20  is stopped. In Step S 106 , the controller  10  may also move the recording heads  30  from the retracted position to the printing position while transporting the printing paper  9  at a transport speed lower than that during the printing. This reduces the useless feed of the printing paper  9 . 
     If the on-movement transport speed V′ is lower than the on-printing transport speed V, the transport speed of the printing paper  9  by means of the transport mechanism  20  may be equal to the on-movement transport speed V′ in Steps S 104  to S 106 . 
     While the printing step is suspended in Steps S 104  to S 106 , the controller  10  according to the present embodiment also stores a virtual last start position that is the last start position on the printing paper  9  into the storage part  13  if printing continues. In other words, the controller  10  causes a first virtual last start position P 21  shown in  FIG. 4  to be stored as the virtual last start position after printing period T from the last start position P 1  before the suspension of the printing. Subsequently, the controller  10  updates a second virtual last start position P 22  as a new virtual last start position. Thereafter, the controller  10  updates the virtual last start position in the same manner. 
     In the present embodiment, the printing of the start position markers  91  continues while the printing step is suspended in Steps S 104  to S 106 , as shown in  FIG. 4 . The retracted position of the recording heads  30  in the present embodiment lies vertically above the printing position of the recording heads  30 . This allows the printing of the start position markers  91  while the recording heads  30  are retracted. However, the distance between the printing paper  9  and the recording heads  30  in the retracted position is longer than that between the printing paper  9  and the recording heads  30  in the printing position. This causes imperfections such as misregistration as compared with the ordinary start position markers  91  and unclear patterns. In this manner, the printing of the start position markers  91  is performed, although imperfect, while the printing step is suspended. This allows an operator to roughly grasp the printing periods T when visually recognizing the printing paper  9 . 
     After the movement of the recording heads  30  in Step S 106  is completed, the controller  10  determines a printing restart position P 3  at the time of restart of printing, based on a virtual last start position P 2   n  at that point of time. Then, the controller  10  restarts the printing of the unit images  92  by means of the recording heads  30  from the printing restart position P 3  (Step S 107 ). 
     The printing restart position P 3  shall be a position spaced the printing period T apart from the virtual last start position P 2   n  in a downstream direction. Thus, the printing restart position P 3  is a position an integral multiple of the printing period T apart from the last start position P 1  before the suspension of the printing. 
     In this manner, the present embodiment causes the printing period before the suspension of the printing to coincide with the printing period after the restart of the printing. In other words, a difference between the periods of the image recording positions before and after the suspension of the printing step is restrained. This eliminates the step of adjusting the printing period on the printing paper  9  again in the post-processing machine for part of the printing paper  9  after the suspension of the printing when the post-processing machine processes the printing paper  9  after the printing. That is, the step of processing in the post-processing machine from part of the printing paper  9  before the suspension of the printing to part of the printing paper  9  after the restart of the printing is performed continuously without the need for the suspension of the operation during the use of the post-processing machine for the recognition of the printing period and the need for the provision of an apparatus for sensing the printing period after the restart of the printing in the post-processing machine. 
     Next, the step of calculating the remaining job count N before suspension and the on-movement transport speed V′ in Step S 102  will be discussed with reference to  FIG. 5 . 
     In Step S 102 , the controller  10  initially judges whether the distance Lo from the detection position of the splice detector  40  to an upstream end of the recording region Rp as measured in the transport direction is longer than the sum of the printing period T and the length Lp of the recording region Rp as measured in the transport direction or not (Step S 201 ). If the controller  10  judges that the distance Lo is not greater than the distance (T+Lp) in Step S 201 , the procedure proceeds to Step S 202 . 
     While the unit image  92  being printed near the upstream end of the recording region Rp at the time of detection of the splice part  90  is printed completely to the end after the detection of the splice part  90 , the printing paper  9  is transported downstream for the distance (T+Lp) that is the sum of the printing period T and the distance Lp at the maximum. If it is judge in Step S 201  that Lo≤(T+Lp) and if the unit image  92  being printed near the upstream end of the recording region Rp at the time of detection of the splice part  90  is printed completely to the end, the splice part  90  reaches the recording region Rp during the printing. At this time, there is apprehension that the splice part  90  comes in contact with the recording heads  30 . To prevent this, the remaining job count N is set to 0 in Step S 202 . Thus, the unit image  92  being printed is not completely printed to the end in Step S 103 , but the printing is promptly suspended. 
     If it is judged that Lo≤(T+Lp) and if there are at least two unit images  92  being printed in the recording region Rp, the printing of all of the unit images  92  is promptly suspended, but at least an upstream one of the unit images  92  may be printed completely to the end. 
     In Step S 202 , the on-movement transport speed V′ is also set to a speed lower than the on-printing transport speed V, as required. For example, if the distance Lo is shorter than an on-movement transport distance Lm, the on-movement transport speed V′ is set to a speed lower than the on-printing transport speed V. The on-movement transport distance Lm refers to a distance that the printing paper  9  travels while the recording heads  30  are moved from the printing position to the retracted position in Step S 104  in the case where the printing paper  9  is transported at the on-printing transport speed V that is the transport speed of the printing paper  9  during the printing. 
     If it is judged in Step S 201  that Lo&gt;(T+Lp), the controller  10  then judges whether the distance Lo is longer than the sum of the printing period T, the length Lp of the recording region Rp as measured in the transport direction and the on-movement transport distance Lm or not (Step S 203 ). 
     If it is judged in Step S 203  that the distance Lo is longer than the sum of the printing period T, the length Lp and the on-movement transport distance Lm, the procedure proceeds to Step S 204 . While the unit image  92  being printed near the upstream end of the recording region Rp at the time of detection of the splice part  90  is printed completely to the end after the detection of the splice part  90 , the printing paper  9  is transported downstream for the distance (T+Lp) that is the sum of the printing period T and the distance Lp at the maximum. Thereafter, when the recording heads  30  are moved while the on-printing transport speed V is maintained, the printing paper  9  is transported further downstream for the on-movement transport distance Lm. 
     Thus, if Lo&gt;(T+Lp+Lm) and if the recording heads  30  are moved while the transport speed of the printing paper  9  is maintained at the on-printing transport speed V after the unit image  92  being printed at the time of detection of the splice part  90  is printed completely to the end, the splice part  90  does not reach the recording region Rp before the end of the movement of the recording heads  30 . Thus, the on-movement transport speed V′ is set to V in Step S 204 . 
     In Step S 204 , the integer part of the quotient of the distance (Lo−Lm) divided by the printing period T is defined as the remaining job count N. By calculating the remaining job count N in this manner, the splice part  90  does not reach the recording region Rp before the end of the movement of the recording heads  30  if the recording heads  30  are moved after the printing of the unit image  92  being printed at the time of detection of the splice part  90  and the subsequent unit image(s)  92  corresponding to (N−1) period(s). This achieves an increase in the number of unit images  92  printed on the printing paper  9  while restraining the splice part  90  from coming in contact with the recording heads  30 . 
     On the other hand, if the controller  10  judges that the distance Lo is not longer than the sum of the printing period T, the length Lp and the on-movement transport distance Lm in Step S 203 , the procedure proceeds to Step S 205 . At this time, the distance Lo is as follows: (T+Lp)&lt;Lo≤(T+Lp+Lm). 
     While the unit image  92  being printed near the upstream end of the recording region Rp at the time of detection of the splice part  90  is printed completely to the end after the detection of the splice part  90 , the printing paper  9  is transported downstream for the distance (T+Lp) that is the sum of the printing period T and the distance Lp at the maximum. At this point of time, the splice part  90  does not reach the recording region Rp. Thus, the remaining job count N is set to 1 in Step S 205 . 
     Thereafter, when the recording heads  30  are moved while the on-printing transport speed V is maintained, the printing paper  9  is transported further downstream for the on-movement transport distance Lm. Thus, the splice part  90  reaches the recording region Rp before the end of the movement of the recording heads  30 . It is hence necessary that the transport speed of the printing paper  9  is set to a speed lower than the on-printing transport speed V after the unit image  92  being printed near the upstream end of the recording region Rp at the time of detection of the splice part  90  is printed completely to the end. In Step S 205 , the on-movement transport speed V′ lower than the on-printing transport speed V is calculated in accordance with the length Lo. This restrains the splice part  90  from reaching the recording region Rp before the end of the movement of the recording heads  30 . 
     In this manner, the calculation of the suitable remaining job count N and the suitable on-movement transport speed V′ in the remaining job count calculation step in Step S 102  reduces waste of the printing paper  9  while restraining the splice part  90  from coming in contact with the recording heads  30 . 
     &lt;3. Modifications&gt; 
     While the one embodiment according to the present invention has been described hereinabove, the present invention is not limited to the aforementioned embodiment. 
     In the aforementioned embodiment, the on-movement transport speed V′ is made equal to the on-printing transport speed V in Step S 204  if the distance Lo is sufficiently long. The present invention, however, is not limited to this. In the step of switching from the printing position to the retracted position in Step S 104 , the printing paper  9  may be transported at a transport speed lower than the on-printing transport speed V if the distance Lo is sufficiently long. This further shortens a printing suspension region on the printing paper  9 . 
     In the aforementioned embodiment, the recording heads  30  are moved for the purpose of switching the relative position of the recording heads  30  and the recording region Rp to the printing position and to the retracted position. The present invention, however, is not limited to this. The platen rollers  222  constituting the recording region Rp may be moved for the purpose of switching the relative position of the recording heads  30  and the recording region Rp. 
     The printing apparatus according to the aforementioned embodiment prints images on the printing paper  9  serving as the recording medium. However, the printing apparatus according to the present invention may be configured to print a pattern of images and the like on a sheet-like recording medium other than general paper (for example, a film made of resin and the like). 
     The components described in the aforementioned embodiment and in the modifications may be consistently combined together, as appropriate. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Printing apparatus 
               9  Printing paper 
               10  Controller 
               12  Memory 
               13  Storage part 
               20  Transport mechanism 
               30  Recording heads 
               31  Head moving mechanisms 
               40  Splice detector 
               50  UV lamp 
               90  Splice part 
               91  Start position markers 
               92  Unit images 
               221  Encoder rollers 
               222  Platen rollers