Patent Publication Number: US-2022234346-A1

Title: Printer, control method, and non-transitory computer-readable medium storing computer-readable instructions

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-011953 filed Jan. 28, 2021. The contents of the foregoing application are hereby incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to a printer, a control method, and a non-transitory computer-readable medium storing computer-readable instructions. 
     A printer is provided with a check sensor, and performs printing on a print medium on a set tray. At the time of printing, the set tray is conveyed from a set position to a stand-by position. After that, the set tray is turned back from the stand-by position and is conveyed toward a printing position. The printing is performed at the printing position, and the set tray is returned to the set position. The check sensor detects wrinkling of the print medium on the set tray. When the set tray is conveyed from the set position to the printing position, if the wrinkling of the print medium is detected by the check sensor, the set tray is returned to the set position without the printer performing the printing. 
     SUMMARY 
     In the above-described printer, when the wrinkling of the print medium is detected by the check sensor, a user smooths out the wrinkling of the print medium in a state in which the set tray has been returned to the set position. Thus, there is a possibility that printing productivity may deteriorate. 
     Embodiments of the broad principles derived herein provide a printer, a control method, and a non-transitory computer-readable medium storing computer-readable instructions. 
     A first aspect of the present disclosure relates to a printer including: a head provided with a nozzle surface; a platen configured to support a print medium, the platen configured to move relative to the head in a discharge direction of ink by the head, and in a conveyance direction intersecting the discharge direction; a first sensor configured to detect the print medium positioned at a first detection position, the first detection position being separated by a first detection distance from the nozzle surface in the discharge direction; a processor; and a memory storing computer-readable instructions that, when executed by the processor, cause the processor to perform processes comprising: performing first conveyance processing of conveying the platen in the conveyance direction relative to the head, toward a printing position at which the nozzle surface faces the platen in the discharge direction; performing first separation processing of moving the platen relative to the nozzle surface and separating the platen from the nozzle surface in the discharge direction, when the print medium is detected by the first sensor after a start of the first conveyance processing; and performing second conveyance processing of conveying the platen in the conveyance direction relative to the head, toward the printing position, after performing the first separation processing. 
     Since the first separation processing and the second conveyance processing are performed even when the print medium is at the first detection position, it is not necessary for a user to rearrange the print medium on the platen. Thus, the printer can improve printing productivity. 
     A second aspect of the present disclosure relates to a control method of a printer, the control method including: performing first conveyance processing of conveying a platen relative to a head in a conveyance direction, toward a printing position, the platen configured to support a print medium, the conveyance direction being intersecting to a discharge direction of ink by the head, and the printing position being a position at which a nozzle surface of the head faces the platen in the discharge direction; performing first separation processing of moving the platen relative to the nozzle surface and separating the platen from the nozzle surface in the discharge direction, when, after a start of the first conveyance processing, the print medium is detected by a first sensor configured to detect the print medium positioned at a first detection position separated from the nozzle surface in the discharge direction by a first detection distance; and performing second conveyance processing of conveying the platen in the conveyance direction relative to the head, toward the printing position, after performing the first conveyance processing. 
     The second aspect can achieve the same effects as those of the first aspect. 
     A third aspect of the present disclosure relates to a non-transitory computer-readable medium storing computer-readable instructions that, when executed, cause a computer of a printer to perform processes including: performing first conveyance processing of conveying a platen relative to a head in a conveyance direction, toward a printing position, the platen configured to support a print medium, the conveyance direction being intersecting to a discharge direction of ink by the head, and the printing position being a position at which a nozzle surface of the head faces the platen in the discharge direction; performing first separation processing of moving the platen relative to the nozzle surface and separating the platen from the nozzle surface in the discharge direction, when, after a start of the first conveyance processing, the print medium is detected by a first sensor configured to detect the print medium positioned at a first detection position separated from the nozzle surface in the discharge direction by a first detection distance; and performing second conveyance processing of conveying the platen in the conveyance direction relative to the head, toward the printing position, after performing the first conveyance processing. 
     The third aspect can achieve the same effects as those of the first aspect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be described below in detail with reference to the accompanying drawings in which: 
         FIG. 1  is a perspective view of a printer as seen from the front left and above; 
         FIG. 2  is a perspective view of the printer as seen from the front left and above, without an upper portion of a housing; 
         FIG. 3  includes cross-sectional views as seen in the direction of arrows along a line A-A, when a platen is positioned at a set position; 
         FIG. 4  is a cross-sectional view as seen in the direction of the arrows along the line A-A when the platen is positioned at a return position; 
         FIG. 5  is a cross-sectional view as seen in the direction of the arrows along the line A-A when the platen is positioned at a printing position; 
         FIG. 6  is a block diagram showing an electrical configuration of the printer; 
         FIG. 7  is a flowchart of main processing; 
         FIG. 8  is a flowchart of the main processing; 
         FIG. 9  is a flowchart of the main processing; 
         FIG. 10  is a schematic diagram when a wrinkle of a print medium is positioned at a first detection position; 
         FIG. 11  is a schematic diagram when the thick print medium is positioned at the first detection position; and 
         FIG. 12  is a schematic diagram when the print medium is positioned lower than a second detection position. 
     
    
    
     DETAILED DESCRIPTION 
     A printer  1  according to an embodiment of the present disclosure will be explained with reference to the drawings. The upper side, the lower side, the lower left side, the upper right side, the lower right side, and the upper left side in  FIG. 1  are, respectively, an upper side, a lower side, a left side, a right side, a front side, and a rear side of the printer  1 . In the present embodiment, mechanical elements in the drawings indicate an actual scale. 
     An overall configuration of the printer  1  will be explained with reference to  FIG. 1  to  FIG. 3 . As shown in  FIG. 1  and  FIG. 2 , the printer  1  is provided with a housing  2 , a platen conveyance mechanism  6 , and a platen  5 . The housing  2  is a cuboid shape and includes a front wall  21 . A hole  22  is formed in the housing  2 . The hole  22  extends from a central portion of the front wall  21  toward the rear. Hereinafter, of the hole  22 , a region surrounded by the front wall  21  is referred to as an “opening  221 .” In other words, the opening  221  is a front end of the hole  22 . An input portion  46  is provided in the front wall  21 , diagonally to the right and above the opening  221 . A user inputs various information to the printer  1  by operating the input portion  46 . 
     As shown in  FIG. 3 , the platen conveyance mechanism  6  is provided, for example, with a shaft  61 , a conveyance belt  62 , a platen support member  3 , a coupling portion  35 , a sub-scanning motor  18  shown in  FIG. 6 , and a raising/lowering motor  16 . The shaft  61  and the conveyance belt  62  are provided in a lower portion of the hole  22 , and each extends in the front-rear direction. The front end of the shaft  61  extends further to the front side than the opening  221 . 
     The platen support member  3  is provided above the shaft  61  and includes a first section  32  and a second section  33 . The first section  32  is plate-shaped and extends in the horizontal direction. The second section  33  extends downward from the rear end portion of the first section  32 . The coupling portion  35  is positioned below the second section  33  and is supported by the shaft  61 . One end of the conveyance belt  62  is coupled to the coupling portion  35 . The sub-scanning motor  18  shown in  FIG. 6  is coupled to the other end of the conveyance belt  62 . 
     The raising/lowering motor  16  is fixed to a rear portion of the coupling portion  35 . An output shaft of the raising/lowering motor  16  extends upward. A ball screw  38  is fixed to the output shaft of the raising/lowering motor  16 . A nut  39  is fixed inside the second section  33 . The ball screw  38  is screwed into the nut  39 . The platen support member  3  is coupled to the coupling portion  35  by the ball screw  38  and the nut  39  being screwed together. 
     According to the configuration of the above-described platen conveyance mechanism  6 , when the raising/lowering motor  16  is driven, the ball screw  38  rotates with respect to the nut  39 . In this way, the platen support member  3  moves up and down. When the sub-scanning motor  18  is driven, the conveyance belt  62  moves the coupling portion  35  in the front-rear direction along the shaft  61 . In this way, the platen support member  3  moves in the front-rear direction. 
     The platen  5  is the shape of a plate that extends in the horizontal direction. The platen  5  is supported by the upper surface of the platen support member  3 . A print medium M is placed on the upper surface of the platen  5 . The print medium M is a cloth, paper, or the like, and is a T-shirt, for example. The platen  5  can be moved in the front-rear direction and the up-down direction by the platen conveyance mechanism  6 . The platen  5  moves in the front-rear direction together with the platen support member  3 . In other words, the front-rear direction of the printer  1  is a sub-scanning direction. Furthermore, the platen  5  moves in the up-down direction together with the platen support member  3 . 
     As shown in  FIG. 2 , the printer  1  is provided with guide rails  11  and  12 , a carriage  20 , and heads  91  to  96 , inside the housing  2 . The guide rail  11  is provided in an upper portion of the hole  22  to the rear of the front wall  21 , and extends in the left-right direction. The guide rail  12  is provided to the rear of the guide rail  11 , and extends in the left-right direction. The carriage  20  is positioned between the guide rail  11  and the guide rail  12  in the front-rear direction, and is supported by the guide rail  11  and the guide rail  12 . The carriage  20  moves in the left-right direction along the guide rail  11  and the guide rail  12  as a result of the driving of a main scanning motor  19  shown in  FIG. 6 . 
     The heads  91  to  96  are mounted to the carriage  20 , and move in the left-right direction together with the carriage  20 . In other words, the left-right direction of the printer  1  is a main scanning direction. The heads  91 ,  92 , and  93  are disposed on the right portion of the carriage  20 , and are aligned in a row from the rear toward the front in the order of the heads  91 ,  92 , and  93 . The heads  94 ,  95 , and  96  are disposed to the left of the row of the heads  91 ,  92 , and  93 , and are aligned in a row from the rear toward the front in the order of the heads  94 ,  95 , and  96 . In the front-rear direction, the head  94  is disposed between the heads  91  and  92 , the head  95  is disposed between the heads  92  and  93 , and the head  96  is disposed at a position displaced to the front with respect to the head  93 . 
     As shown in  FIG. 3 , nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  are provided, respectively, in the lower surfaces of the heads  91  to  96 . A nozzle position V 0  indicates a position, in the up-down direction, of the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 , and is prescribed by the carriage  20 . In the present embodiment, the nozzle position V 0  is positioned lower than the lower surface of the carriage  20 . 
     The nozzle position V 0  is defined by the lowermost surface of the carriage  20  and the heads  91  to  96 . In the present embodiment, the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  are positioned lower than the bottom surface of the carriage  20 , and thus, the position in the up-down direction of the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  is the nozzle position V 0 . For example, the bottom surface of the carriage  20  may be positioned lower than the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 . In this case, the position in the up-down direction of the bottom surface of the carriage  20  is the nozzle position V 0 . 
     A plurality of nozzles (not shown in the drawings) are aligned in the front-rear direction and the left-right direction in each of the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 . The heads  91  and  94  discharge white ink downward from each of the nozzles. The heads  92  and  95  discharge a pretreatment agent, special ink, and the like downward from each of the nozzles. The heads  93  and  96  discharge color ink downward from each of the nozzles. 
     A conveyance operation of the platen  5  by the platen conveyance mechanism  6  and a printing operation by the heads  91  to  96  will be explained with reference to  FIG. 3  to  FIG. 5 . When the conveyance operation to convey the platen  5  by the platen conveyance mechanism  6  is started, the platen  5  is conveyed to the rear from a set position shown in  FIG. 3  to a return position shown in  FIG. 4 . The platen  5  is turned back at the return position shown in  FIG. 4  and is conveyed toward the front to the set position shown in  FIG. 3 . In this way, the conveyance operation of the platen  5  by the platen conveyance mechanism  6  ends. 
     As shown in  FIG. 3 , the set position is a position at which the platen  5  is disposed further to the front than the front wall  21 . For example, the set position is a front end of a movement range of the platen  5 , and is a start point and an end point of a conveyance path of the platen  5 . The set position is a stand-by position of the platen  5  before the start of printing and after the end of the printing by the printer  1 . The set position is a position of the platen  5  when the print medium M is attached to or removed from the platen  5 . In the present embodiment, when the platen  5  is positioned at the set position, the rear end of the platen  5  is disposed further to the front than the opening  221 . 
     As shown in  FIG. 4 , the return position is a rear end of the movement range of the platen  5 , and is an intermediate position on the conveyance path of the platen  5 . In the present embodiment, when the platen  5  is positioned at the return position, the front end of the platen  5  is disposed further to the rear than any of the heads  91  to  96 . 
     As shown in  FIG. 5 , the platen  5  passes through a printing position in the course of the conveyance operation. The printing position is a position at which the platen  5  faces one of the heads  91  to  96  in the up-down direction, is further to the rear than the set position shown in  FIG. 3 , and is further to the front than the return position shown in  FIG. 4 . 
     The printer  1  moves the platen  5  in the front-rear direction (the sub-scanning direction) between the set position shown in  FIG. 3  and the return position shown in  FIG. 4 , and also moves the heads  91  to  96  in the left-right direction (the main scanning direction) on the conveyance path of the platen  5 . In this way, the printer  1  conveys the print medium M (refer to  FIG. 3 ) on the platen  5  in the front-rear direction and the left-right direction with respect to the heads  91  to  96 . While conveying the print medium M on the platen  5  with respect to the heads  91  to  96 , in a state in which the platen  5  is positioned at the printing position, the printer  1  discharges the ink from each of the nozzles of the heads  91  to  96 . In this way, the printer  1  performs the printing on the print medium M. 
     The electrical configuration of the printer  1  will be explained with reference to  FIG. 6 . The printer  1  is provided with a control board  10 . A CPU  41 , a ROM  42 , a RAM  43 , and a flash memory  44  are provided on the control board  10 . The CPU  41  controls the printer  1  and is electrically connected to the ROM  42 , the RAM  43 , and the flash memory  44 . The ROM  42  stores a control program used for the CPU  41  to control operations of the printer  1 , and various pieces of information and the like needed by the CPU  41  when executing various programs. The ROM  42  stores, on the basis of a rotation angle of the sub-scanning motor  18 , the position of the platen  5  in the front-rear direction (the set position, the printing position, the return position, a detection zone to be described later, and the like). The RAM  43  temporarily stores various data used by the control program. The flash memory  44  is a non-volatile memory, and stores a first retry setting, a second retry setting, print data for performing the printing (all to be described later), and the like. 
     The main scanning motor  19 , the sub-scanning motor  18 , the raising/lowering motor  16 , a head drive portion  17 , a notification portion  45 , the input portion  46 , an origin sensor  49 , a first sensor  47 , and a second sensor  48  are electrically connected to the CPU  41 . The main scanning motor  19 , the sub-scanning motor  18 , the raising/lowering motor  16 , and the head drive portion  17  are driven by control by the CPU  41 . 
     An encoder  181  is provided in the sub-scanning motor  18 . The encoder  181  detects the rotation angle of the sub-scanning motor  18 , and outputs a detection result to the CPU  41 . The head drive portion  17  is a piezoelectric element or the like, and, as a result of the driving of the head drive portion  17 , the heads  91  to  96  are caused to discharge the ink from each of the nozzles. 
     The notification portion  45  is a speaker, a display screen, or the like, and outputs an error sound, an error screen, or the like. The input portion  46  is a touch panel or the like, and outputs information to the CPU  41  in accordance with an operation by the user. By operating the input portion  46 , the user can input, to the printer  1 , a printing command for starting the printing by the printer  1 , and the like. 
     The origin sensor  49  is provided in the raising/lowering motor  16 , and can detect an origin of a rotation position of the raising/lowering motor  16 . When the origin sensor  49  has detected the origin of the rotation position of the raising/lowering motor  16 , the origin sensor  49  outputs a detection signal to the CPU  41 . On the basis of the detection signal from the origin sensor  49 , the CPU  41  can determine whether the rotation position of the raising/lowering motor  16  is positioned at the origin. 
     As shown in  FIG. 3 , the first sensor  47  and the second sensor  48  are provided on a left edge  211 . The left edge  211  is a portion of the front wall  21  that prescribes the left end of the opening  221 , and extends in the up-down direction. The second sensor  48  is positioned diagonally to the front of and below the first sensor  47 . The first sensor  47  and the second sensor  48  are reflective optical sensors, and each is provided with a light emitting portion and a light receiving portion. The first sensor  47  and the second sensor  48  each emit light to the right from the light emitting portion, and receive the light using the light receiving portion. 
     The first sensor  47  can detect the print medium M positioned at a first detection position V 1 . The first detection position V 1  is a position in the up-down direction of the first sensor  47 , and is, for example, a position in the up-down direction of the light emitting portion and the light receiving portion of the first sensor  47 . The first detection position V 1  is a position separated downward by a predetermined first detection distance D 1  from the nozzle position V 0 . For example, when the first sensor  47  has detected the print medium M that is at the first detection position V 1 , the first sensor  47  outputs a detection signal to the CPU  41 . On the basis of the detection signal from the first sensor  47 , the CPU  41  can determine whether or not the print medium M on the platen  5  is positioned at the first detection position V 1 . 
     The second sensor  48  can detect the print medium M positioned at a second detection position V 2 . The second detection position V 2  is a position in the up-down direction of the second sensor  48  and is, for example, a position in the up-down direction of the light emitting portion and the light receiving portion of the second sensor  48 . The second detection position V 2  is a position separated downward by a predetermined second detection distance D 2  from the nozzle position V 0 . The second detection distance D 2  is greater than the first detection distance D 1 . Thus, the second detection position V 2  is positioned lower than the first detection position V 1 . Note that the first detection distance D 1  and the second detection distance D 2  are not limited to a particular value, but in the present embodiment, the first detection distance D 1  is 1.2 mm and the second detection distance D 2  is 4.7 mm. For example, when the second sensor  48  has detected the print medium M that is at the second detection position V 2 , the second sensor  48  outputs a detection signal to the CPU  41 . On the basis of the detection signal from the second sensor  48 , the CPU  41  can determine whether or not the print medium M on the platen  5  is positioned at the second detection position V 2 . 
     In the present embodiment, in order to reduce a possibility of the print medium M and the heads  91  to  96  coming into contact with each other, when the first sensor  47  has detected the print medium M, the printer  1  does not perform the printing in the state in which the first sensor  47  has detected the print medium M. Furthermore, in order to suppress a deterioration in image quality of a print image caused by landing position displacement of the ink, as a result of the print medium M and the heads  91  to  96  being separated from each other, when the second sensor  48  has not detected the print medium M, the printer  1  does not perform the printing in the state in which the second sensor  48  has not detected the print medium M. Hereinafter, an example of main processing will be explained. 
     The main processing will be explained with reference to  FIG. 3  to  FIG. 5  and  FIG. 7  to  FIG. 12 . When a power supply of the printer  1  is turned on, the CPU  41  executes the main processing by reading out the control program from the ROM  42  and operating the control program. In the main processing, the conveyance operation of the platen  5 , a print operation by the heads  91  to  96 , and the like are performed. Hereinafter, processing at step S 45  to step S 54 , and at step S 45  to step S 58  will be referred to as “first retry control,” and processing at step S 63  to step S 66  will be referred to as “second retry control.” When the main processing is started, it is assumed that the platen  5  is positioned at the set position shown in  FIG. 3 . The user attaches the unprinted print medium M to the platen  5  in the state in which the platen  5  is positioned at the set position shown in  FIG. 3 . 
     As shown in  FIG. 7 , when the main processing is started, the CPU  41  determines whether a first operation has been performed on the input portion  46  (step S 11 ). The first operation is an operation relating to the first retry setting to be described later. When the first operation has not been performed (no at step S 11 ), the CPU  41  shifts the processing to step S 13 . 
     When the first operation has been performed (yes at step S 11 ), the CPU  41  performs first retry setting processing (step S 12 ). In the first retry setting processing, the CPU  41  sets, in the flash memory  44 , a first retry setting to one of ON or OFF, in accordance with the first operation. When the first retry setting is ON, the CPU  41  decides to perform the first retry control to be described later. When the first retry setting is OFF, the CPU  41  decides not to perform the first retry control. In the first retry setting processing, when the first retry setting is ON, in the flash memory  44 , the CPU  41  further sets a length of a first movement distance L 1  and of a second movement distance L 2  (refer to  FIG. 11 ), to be described later, in accordance with the first operation. 
     The CPU  41  determines whether or not a second operation has been performed on the input portion  46  (step S 13 ). The second operation is an operation relation to the second retry setting to be described later. When the second operation has not been performed (no at step S 13 ), the CPU  41  shifts the processing to step S 21 . 
     When the second operation has been performed (yes at step S 13 ), the CPU  41  performs second retry setting processing (step S 14 ). In the second retry setting processing, the CPU  41  sets, in the flash memory  44 , a second retry setting to one of ON or OFF, in accordance with the second operation. When the second retry setting is ON, the CPU  41  decides to perform the second retry control to be described later. When the second retry setting is OFF, the CPU  41  decides not to perform the second retry control. 
     The CPU  41  determines whether or not a print command has been acquired via the input portion  46  (step S 21 ). When the print command has not been acquired (no at step S 21 ), the CPU  41  returns the processing to step S 11 . When the print command has been acquired (yes at step S 21 ), the CPU  41  controls the sub-scanning motor  18  and starts to convey the platen  5  to the rear (step S 22 ). In this way, the platen  5  is conveyed from the set position shown in  FIG. 3  toward the return position shown in  FIG. 4 . The CPU  41  performs the following processing while conveying the platen  5 . 
     On the basis of a detection result from the encoder  181 , the CPU  41  determines whether or not the platen  5  has reached a detection zone start position (step S 23 ). The detection zone is a zone of the conveyance path of the platen  5  in which the CPU  41  performs control of the conveyance operation or the platen  5  on the basis of the detection signals from the first sensor  47  and the second sensor  48 . The detection zone start position is positioned further to the rear than the set position shown in  FIG. 3 , and is, for example, a position of the platen  5  when the rear end of the platen  5  is positioned at the opening  221 . When the platen  5  is positioned at the detection zone start position, the rear end of the platen  5  is, for example, aligned with a position in the front-rear direction of the second sensor  48 . 
     When the platen  5  is positioned further to the front than the detection zone start position (no at step S 23 ), the CPU  41  repeats the processing at step S 23 . When the platen  5  has reached the detection zone start position (yes at step S 23 ), the CPU  41  determines, on the basis of the detection signal from the first sensor  47 , whether or not the print medium M at the first detection position V 1  shown in  FIG. 3  has been detected by the first sensor  47  (step S 24 ). 
     As shown in  FIG. 3 , when there is no wrinkle in the print medium M, or when the wrinkle of the print medium M is relatively small, and the like, the upper surface of the print medium M is positioned lower than the first detection position V 1 . As shown in  FIG. 7 , when the print medium M at the first detection position V 1  is not detected by the first sensor  47  (no at step S 24 ), the CPU  41  determines, on the basis of the detection signal from the second sensor  48 , whether or not the print medium M at the second detection position V 2  has been detected by the second sensor  48  (step S 25 ). 
     As shown in  FIG. 3 , when the platen  5  has not been excessively lowered, or the like, the upper surface of the print medium M is positioned higher than the second detection position V 2 . As shown in  FIG. 7 , when the print medium M at the second detection position V 2  has been detected by the second sensor  48  (yes at step S 25 ), the CPU  41  determines, on the basis of the detection result from the encoder  181 , whether or not the platen  5  has reached a detection zone end position (step S 26 ). The detection zone end position is a position of the platen  5  when the front end of the platen  5  is positioned at the opening  221 , for example. When the platen  5  is positioned at the detection zone end position, the front end of the platen  5  is, for example, aligned with the position in the front-rear direction of the second sensor  48 . 
     When the platen  5  is positioned further to the front than the detection zone end position (no at step S 26 ), the CPU  41  returns the processing to step S 24 . When the platen  5  has reached the detection zone end position (yes at step S 26 ), the CPU  41  determines, on the basis of the detection result from the encoder  181 , whether or not the platen  5  has reached the return position shown in  FIG. 4  (step S 27 ). When the platen  5  is positioned further to the front than the return position shown in  FIG. 4  (no at step S 27 ), the CPU  41  repeats the processing at step S 27 . 
     When the platen  5  has reached the return position shown in  FIG. 4  (yes at step S 27 ), the CPU  41  controls the sub-scanning motor  18  and starts the conveyance of the platen  5  to the front (step S 31 ). In this way, the platen  5  is conveyed from the return position shown in  FIG. 4  toward the printing position shown in  FIG. 5 . 
     The CPU  41  performs print control in a state in which the platen  5  is positioned at the printing position shown in  FIG. 5  (step S 32 ). In the print control, the CPU  41  controls the main scanning motor  19  and the head drive portion  17  in synchronization with the conveyance operation of the platen  5 . For example, the carriage  20  reciprocates in the left-right direction while some or all of the heads  91  to  96  discharge the ink from the nozzles, and after that, the platen  5  is conveyed to the front by a predetermined distance. This operation is repeatedly performed. When the printing on the print medium M is complete, the print control is ended. 
     The CPU  41  controls the sub-scanning motor  18  and conveys the platen  5  to the front to the set position shown in  FIG. 3  (step S 33 ). The CPU  41  returns the processing to step S 11 . The user removes the printed print medium M from the platen  5  in a state in which the platen  5  is positioned at the set position shown in  FIG. 3 , and, when the printing is to be repeated, attaches the unprinted print medium M to the platen  5 . 
     For example, there is a case in which the print medium M has a wrinkle, as shown in  FIG. 10 , or a case in which the thickness of the print medium M in the up-down direction is thick, as shown in  FIG. 11 . In this case, depending on the size of the wrinkle of the print medium M, the thickness of the print medium M in the up-down direction, and the position of the platen  5  in the up-down direction, the upper surface of the print medium M is positioned higher than the first detection position V 1 . When the upper surface of the print medium M is positioned higher than the first detection position V 1 , the print medium M at the first detection position V 1  is detected by the first sensor  47  (yes at step S 24 ). In this case, as shown in  FIG. 8 , the CPU  41  refers to the flash memory  44  and determines whether or not the first retry setting is ON (step S 41 ). 
     When the first retry setting is OFF (no at step S 41 ), the CPU  41  performs first error processing (step S 42 ). In the first error processing, the CPU  41  controls the sub-scanning motor  18  and returns the platen  5  to the set position shown in  FIG. 3 . In this case, the raising/lowering motor  16  is stopped, and thus, the position of the platen  5  in the up-down direction is maintained to be constant. Furthermore, the CPU  41  causes the notification portion  45  to perform error notification. The error notification in the first error processing refers to indicating the fact that the print medium M in the first detection position V 1  has been detected by the first sensor  47 , or the like. The CPU  41  returns the processing to step S 11  shown in  FIG. 7 . In this case, in the state in which the platen  5  is positioned at the set position shown in  FIG. 3 , the user re-arranges the print medium M on the platen  5 , replaces the print medium M, or adjusts the position of the platen  5  in the up-down direction. For example, the user operates the input portion  46  and drives the raising/lowering motor  16 , and moves the platen  5  downward. Alternatively, the user operates a manual adjustment mechanism (not shown in the drawings) and moves the platen  5  downward. After that, the user once more inputs the print command to the printer  1 . 
     When the first retry setting is ON (yes at step S 41 ), the CPU  41  determines, on the basis of the detection signal from the first sensor  47 , whether or not the print medium M at the first detection position V 1  is detected by the first sensor  47  for a predetermined time period or more (step S 43 ). The predetermined time period is stored in the ROM  42  and is shorter than a conveyance time period when the platen  5  is conveyed from the detection zone start position to the detection zone end position, for example. The predetermined time period is longer than 0 seconds. 
     When the print medium M at the first detection position V 1  has been detected by the first sensor  47 , the case is conceivable, for example, in which the print medium M has the wrinkle, as shown in  FIG. 10 , or the case in which the thickness of the print medium M in the up-down direction is thick, as shown in  FIG. 11 . As shown in  FIG. 10 , when the print medium M has the wrinkle, a detection time period of the detection of the print medium M by the first sensor  47  is a time period corresponding to a distance S 1 . When the thickness of the print medium M in the up-down direction is thick, as shown in  FIG. 11 , the detection time period of the detection of the print medium M by the first sensor  47  is a time period corresponding to a distance S 2 . In most cases, the distance S 1  is smaller than the distance S 2 . Thus, when the print medium M is detected by the first sensor  47  for a time period equal to or greater than the predetermined time period, the possibility that the thickness of the print medium M in the up-down direction is thick is higher than when the print medium M is detected by the first sensor  47  for a time period less than the predetermined time period. On the other hand, when the print medium M is detected by the first sensor  47  for the time period less than the predetermined time period, the possibility that the print medium M has the wrinkle is higher than when the print medium M is detected by the first sensor  47  for the time period equal to or greater than the predetermined time period. 
     When the print medium M at the first detection position V 1  is no longer detected by the first sensor  47  before the predetermined time period has elapsed from when the print medium M at the first detection position V 1  is detected by the first sensor  47  (no at step S 43 ), there is a relatively high possibility that the print medium M has the wrinkle (refer to  FIG. 10 ). In this case, the CPU  41  performs second error processing (step S 44 ). 
     In the second error processing, the CPU  41  controls the sub-scanning motor  18  and returns the platen  5  to the set position shown in  FIG. 3 . In this case, the raising/lowering motor  16  is stopped, and thus, the position of the platen  5  in the up-down direction is maintained to be constant. Further, the CPU  41  causes the notification portion  45  to perform the error notification. The error notification in the second error processing refers to indicating the fact that the print medium M in the first detection position V 1  is detected by the first sensor  47  for less than the predetermined time period, that the print medium M has the wrinkle, and the like. The CPU  41  returns the processing to step S 11  in  FIG. 7 . In this case, in the state in which the platen  5  is positioned at the set position shown in  FIG. 3 , the user stretches out the wrinkle of the print medium M. After that, the user once more inputs the print command to the printer  1 . In this way, the printer  1  can suppress the printing from being performed on the print medium M in a wrinkled state. 
     When the print medium M at the first detection position V 1  is detected by the first sensor  47  for the time period equal to or greater than the predetermined time period (yes at step S 43 ), there is a relatively high possibility that the thickness in the up-down direction of the print medium M is thick (refer to  FIG. 11 ). In this case, the CPU  41  stops the driving of the sub-scanning motor  18  and stops the conveyance of the platen  5  (step S 45 ). The CPU  41  counts a retry number and stores the number in the RAM  43  (step S 46 ). The retry number is a number of times that the first retry control is performed. Note that the retry number is reset to “0” in the RAM  43  when the print command has been input (yes at step S 21 ). Further, when the print control has been performed (step S 32 ), and when the second to fourth error processing has been performed (step S 44 , step S 59 , step S 62 ), the retry number is reset to “0” in the RAM  43 . 
     The CPU  41  refers to the RAM  43  and determines whether or not the retry number is 1 (step S 51 ). When the retry number is 1 (yes at step S 51 ), the CPU  41  controls the raising/lowering motor  16  and lowers the platen  5  by the first movement distance L 1  (refer to  FIG. 11 ) set at step S 12  (step S 52 ). In this way, the platen  5  is separated, in the up-down direction, from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 . 
     The CPU  41  controls the sub-scanning motor  18 , and conveys the platen  5  to the front by a predetermined retry distance L 3  (refer to  FIG. 11 ) (step S 53 ). In this way, the platen  5  is conveyed to a retry position. In other words, the retry position is a position further to the front, by the retry distance L 3 , than the position of the platen  5  when the predetermined time period has elapsed from when the print medium M at the first detection position V 1  is detected by the first sensor  47 . The retry position is a position further to the front, by the retry distance L 3 , than a stop position of the platen  5  at step S 45 . The retry distance L 3  is stored in the ROM  42  and is constant, regardless of the stop position of the platen  5  at step S 45 . The retry distance L 3  is longer than a distance in the front-rear direction over which the platen  5  is conveyed during the predetermined time period, for example. The retry distance L 3  is shorter, for example, than a total distance obtained by adding a distance in the front-rear direction between the set position shown in  FIG. 3  and the detection zone start position, and the distance in the front-rear direction over which the platen  5  is conveyed during the predetermined time period. Thus, the retry position is a position further to the front than the detection zone start position, and further to the rear than the set position shown in  FIG. 3 . 
     The CPU  41  controls the sub-scanning motor  18  and starts to convey the platen  5  to the rear (step S 54 ). In this way, the platen  5  is conveyed from the retry position toward the return position shown in  FIG. 4 . The CPU  41  returns the processing to step S 24  in  FIG. 7 . A first cycle of the first retry control (step S 45  to step S 54 ) is performed as described above. When the upper surface of the print medium M has been lowered to a position lower than the first detection position V 1  as a result of the first cycle of the first retry control, at step S 24 , the print medium M is not detected by the first sensor  47  (no at step S 24 ). In this case, after that, the print control is performed (step S 32 ). Thus, it is not necessary for the user to rearrange the print medium M on the platen  5 , to replace the print medium M, or to adjust the position in the up-down direction of the platen  5  in the state in which the platen  5  is positioned at the set position shown in  FIG. 3 . As a result, it is not necessary for the user to input the print command once more to the printer  1 . As a result, the printer  1  can improve printing productivity. 
     When the thickness of the print medium M in the up-down direction is relatively thick, when the first movement distance L 1  is relatively small, and the like, in the first cycle of the first retry control, that is, in the lowering of the platen  5  by the first movement distance L 1 , there is a case in which the upper surface of the print medium M is not lowered to a position lower than the first detection position V 1 . In this case, the print medium M at the first detection position V 1  is once more detected by the first sensor  47  for a period equal to or greater than the predetermined time period (yes at step S 24 ; yes at step S 41 ; yes at step S 43 ). In this case, the retry number is not 1 (no at step S 51 ), and the CPU  41  determines whether or not the retry number is 2 (step S 55 ). 
     When the retry number is 2 (yes at step S 55 ), the CPU  41  controls the raising/lowering motor  16  and lowers the platen  5  by the second movement distance L 2  (refer to  FIG. 11 ) set at step S 12  (step S 56 ). In this way, the platen  5  is separated, in the up-down direction, from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 . The CPU  41  controls the sub-scanning motor  18 , and conveys the platen  5  to the front by the predetermined retry distance L 3  (refer to  FIG. 11 ) (step S 57 ). In this way, the platen  5  is conveyed to the retry position. 
     The CPU  41  controls the sub-scanning motor  18  and starts to convey the platen  5  to the rear (step S 58 ). In this way, the platen  5  is conveyed from the retry position toward the return position shown in  FIG. 4 . The CPU  41  returns the processing to step S 24  in  FIG. 7 . A second cycle of the first retry control (step S 45  to step S 58 ) is performed as described above. When the upper surface of the print medium M has been lowered to a position lower than the first detection position V 1  as a result of the second cycle of the first retry control, at step S 24 , the print medium M is not detected by the first sensor  47  (no at step S 24 ). In this case, after that, the print control is performed (step S 32 ). 
     Even in the second cycle of the first retry control, that is, even in the lowering of the platen  5  by the first movement distance L 1  and the second movement distance L 2 , there is a case in which the upper surface of the print medium M is not lowered to a position lower than the first detection position V 1 . In this case, the print medium M at the first detection position V 1  is once more detected by the first sensor  47  for a period equal to or greater than the predetermined time period (yes at step S 24 ; yes at step S 41 ; yes at step S 43 ; no at S 51 ). In this case, the retry number is 3 (no at step S 55 ), and the CPU  41  performs the third error processing (step S 59 ). In other words, in the present embodiment, the first retry control is only performed up to a maximum of two times for each time the print command is input. 
     In the third error processing, the CPU  41  controls the sub-scanning motor  18  and returns the platen  5  to the set position shown in  FIG. 3 . In this case, the raising/lowering motor  16  is stopped, and thus, the position of the platen  5  in the up-down direction is maintained to be constant. Further, the CPU  41  causes the notification portion  45  to perform the error notification. The error notification in the third error processing refers to indicating the fact that the second cycle of the first retry control has already been performed, and the like. The CPU  41  returns the processing to step S 11  in  FIG. 7 . In this case, in the state in which the platen  5  is positioned at the set position shown in  FIG. 3 , the user rearranges the print medium M on the platen  5 , replaces the print medium M, or adjusts the position of the platen  5  in the up-down direction. After that, the user once more inputs the print command to the printer  1 . 
     As shown in  FIG. 12 , there is a case, for example, in which the platen  5  has been excessively lowered. In this case, the upper surface of the print medium M is positioned lower than the second detection position V 2 . As shown in  FIG. 7 , when the upper surface of the print medium M is positioned lower than the second detection position V 2 , the print medium M at the second detection position V 2  is not detected by the second sensor  48  (no at step S 25 ). In this case, as shown in  FIG. 9 , the CPU  41  refers to the flash memory  44  and determines whether or not the second retry setting is ON (step S 61 ). 
     When the second retry setting is OFF (no at step S 61 ), the CPU  41  performs the fourth error processing (step S 62 ). In the fourth error processing, the CPU  41  controls the sub-scanning motor  18  and returns the platen  5  to the set position shown in  FIG. 3 . In this case, the raising/lowering motor  16  is stopped, and thus, the position of the platen  5  in the up-down direction is maintained to be constant. Further, the CPU  41  causes the notification portion  45  to perform the error notification. The error notification in the fourth error processing refers to indicating the fact that the print medium M is not present at a position above the second detection position V 2 , that the platen  5  has been excessively lowered, and the like. The CPU  41  returns the processing to step S 11  in  FIG. 7 . In this case, in the state in which the platen  5  is positioned at the set position shown in  FIG. 3 , the user adjusts the position of the platen  5  in the up-down direction. After that, the user once more inputs the print command to the printer  1 . 
     When the second retry setting is ON (yes at step S 61 ), the CPU  41  stops the driving of the sub-scanning motor  18  and stops the conveyance of the platen  5  (step S 63 ). The CPU  41  controls the raising/lowering motor  16  on the basis of the detection signal from the origin sensor  49 , and raises the platen  5  to a reference position V 3  shown in  FIG. 12  (step S 64 , refer to an arrow W in  FIG. 12 ). In this way, the platen  5  is caused to approach the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 , in the up-down direction. The reference position V 3  is a position of the platen  5  in the up-down direction when the rotation position of the raising/lowering motor  16  is positioned at the origin. 
     As shown in  FIG. 12 , the reference position V 3  is a position separated downward from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  by a predetermined reference distance D 3 . The reference distance D 3  is greater than the first detection distance D 1  and is smaller than the second detection distance D 2 . Thus, the reference position V 3  is a position between the first detection position V 1  and the second detection position V 2  in the up-down direction. Note that the reference distance D 3  is not limited to a specific value, but in the present embodiment, the reference distance D 3  is 4.4 mm. 
     As shown in  FIG. 9 , the CPU  41  controls the sub-scanning motor  18  and conveys the platen  5  to the front by the predetermined retry distance L 3  (refer to  FIG. 12 ) (step S 65 ). In this way, the platen  5  is conveyed to the retry position. The CPU  41  controls the sub-scanning motor  18  and starts to convey the platen  5  to the rear (step S 66 ). In this way, the platen  5  is conveyed from the retry position toward the return position shown in  FIG. 4 . The CPU  41  returns the processing to step S 24  in  FIG. 7 . The second retry control is performed (step S 63  to step S 66 ) as described above. When the upper surface of the print medium M has been raised to a position higher than the second detection position V 2  as a result of the second retry control, at step S 25 , the print medium M is detected by the second sensor  48  (yes at step S 25 ). In this case, after that, the print control is performed (step S 32 ). Thus, it is not necessary for the user to adjust the position in the up-down direction of the platen  5  in the state in which the platen  5  is positioned at the set position shown in  FIG. 3  and once more input the print command to the printer  1 . As a result, the printer  1  can improve the printing productivity. 
     As described above, the printer  1  is provided with the heads  91  to  96 , the platen  5 , the first sensor  47 , and the CPU  41 . The nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  are provided on the heads  91  to  96 . The platen  5  is provided to be movable relative to the heads  91  to  96  in the up-down direction and the front-rear direction, and supports the print medium M. The direction from up to down is a discharge direction of the ink by the heads  91  to  96 . The front-rear direction intersects the up-down direction. The first sensor  47  detects the print medium M at the first detection position V 1 . The first detection position V 1  is the position separated downward from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 , by the first detection distance D 1 . The CPU  41  performs first conveyance processing (step S 22 ). In the first conveyance processing, the CPU  41  conveys the platen  5  relative to the heads  91  to  96  in the front-rear direction, toward the printing position. The printing position is the position at which one of the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  faces the platen  5  in the up-down direction. When the print medium M is detected by the first sensor  47  after the start of the first conveyance processing, the CPU  41  performs first separation processing (step S 52 ). In the first separation processing, the CPU  41  causes the platen  5  to move relative to and move away from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  in the up-down direction. After performing the first separation processing, the CPU  41  performs second conveyance processing (step S 54 ). In the second conveyance processing, the CPU  41  conveys the platen  5  relative to the heads  91  to  96  in the front-rear direction, toward the printing position. 
     Since the first separation processing and the second conveyance processing are performed even when the print medium M is at the first detection position V 1 , it is not necessary for the user to rearrange the print medium M on the platen  5 . Thus, the printer  1  can improve the printing productivity. 
     The printer  1  is provided with the flash memory  44 . The flash memory  44  stores one of ON and OFF for the first retry setting. In the state in which ON is stored in the flash memory  44  for the first retry setting, when the print medium M is detected by the first sensor  47  after the start of the first conveyance processing, the CPU  41  performs the first separation processing. In the state in which OFF is stored in the flash memory  44  for the first retry setting, when the print medium M is detected by the first sensor  47  after the start of the first conveyance processing, the CPU  41  performs the first error processing (step S 42 ). In the first error processing, the CPU  41  performs the error notification. 
     In the state in which ON is stored in the flash memory  44  for the first retry setting, even when the print medium M is at the first detection position V 1 , the first separation processing and the second conveyance processing are performed, and thus, the printer  1  can improve the printing productivity. In the state in which OFF is stored in the flash memory  44  for the first retry setting, when the print medium M is at the first detection position V 1 , the first error processing is performed, and thus, the printer  1  can suppress the printing from being performed on the print medium M in the wrinkled state, for example. Thus, the printer  1  can suppress a deterioration in the image quality of the print image. As a result, by storing one of ON and OFF for the first retry setting in the flash memory  44 , the printer  1  can perform the printing in accordance with a respective priority of printing productivity and image quality of the print image, for example. 
     The printer  1  is provided with the second sensor  48 . The second sensor  48  detects the print medium M at the second detection position V 2 . The second detection position V 2  is the position separated downward from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  by the second detection distance D 2 . The second detection distance D 2  is greater than the first detection distance D 1 . When the print medium M is not detected by the second sensor  48  after the start of the first conveyance processing or the second conveyance processing, the CPU  41  performs approach processing (step S 64 ). In the approach processing, the CPU  41  causes the platen  5  to move relative to and approach the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  in the up-down direction. After performing the approach processing, the CPU  41  performs third conveyance processing (step S 66 ). In the third conveyance processing, the CPU  41  conveys the platen  5  relative to the heads  91  to  96  in the front-rear direction, toward the printing position. 
     Even when the print medium M is not at the second detection position V 2 , since the third conveyance processing is performed, it is not necessary for the user to adjust the position of the platen  5  in the up-down direction with respect to the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961 . Thus, the printer  1  can improve the printing productivity. Furthermore, the printer  1  can suppress the deterioration in the image quality of the print image as a result of a discharge distance being greater than the second detection distance D 2 . 
     In the first conveyance processing, the CPU  41  conveys the platen  5  relative to the heads  91  to  96  in the front-rear direction, from the set position toward the printing position. The set position is the position at which the print medium M is attached to and removed from the platen  5 . When the print medium M is detected by the first sensor  47  after the start of the first conveyance processing, after performing the first separation processing, the CPU  41  performs return processing (step S 53 ). In the return processing, the CPU  41  conveys the platen  5  to the retry position. The retry position is a position between the position of the platen  5  when the print medium M is detected by the first sensor  47 , and the set position. In the second conveyance processing, the CPU  41  conveys the platen  5  relative to the heads  91  to  96  in the front-rear direction, from the retry position to the printing position. 
     The conveyance time period of the platen  5  from the retry position to the printing position is shorter than the conveyance time period of the platen  5  from the set position to the printing position. The printer  1  performs the return processing, and thus, the conveyance time period of the platen  5  by the second conveyance processing can be made shorter, compared to when the platen  5  is returned to the set position. Thus, the printer  1  can improve the printing productivity. 
     In the printer  1 , in the first separation processing, the CPU  41  moves the platen  5  relative to the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  in the up-down direction and separates the platen  5  from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  by the first movement distance L 1 . When the print medium M is detected by the first sensor  47  after the start of the second conveyance processing, the CPU  41  performs second separation processing (step S 56 ). In the second separation processing, the CPU  41  move the platen  5  relative to the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  in the up-down direction and separates the platen  5  from the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  by the second movement distance L 2 . The second movement distance L 2  is the distance different from the first movement distance L 1 . After performing the second separation processing, the CPU  41  performs fourth conveyance processing (step S 58 ). In the fourth conveyance processing, the CPU  41  conveys the platen  5  relative to the heads  91  to  96  in the front-rear direction, toward the printing position. 
     For example, when the first movement distance L 1  is greater than the second movement distance L 2 , the possibility that the print medium M is detected by the first sensor  47  after the start of the second conveyance processing is lower than when the first movement distance L 1  is smaller than the second movement distance L 2 . Thus, in this case, the printer  1  can improve the printing productivity. For example, when the first movement distance L 1  is smaller than the second movement distance L 2 , the possibility that the distance in the up-down direction between the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  and the print medium M becomes too large in the first separation processing is smaller than when the first movement distance L 1  is greater than the second movement distance L 2 . Thus, in this case, the printer  1  can suppress the deterioration in the image quality of the print image as a result of the nozzle surfaces  911 ,  921 ,  931 ,  941 ,  951 , and  961  being too far from the print medium M. 
     The CPU  41  performs the first separation processing when the print medium M is detected by the first sensor  47  for a period equal to or greater than the predetermined time period after the start of the first conveyance processing. The CPU  41  performs the second error processing (step S 44 ) when the print medium M is detected by the first sensor  47  for a period less than the predetermined time period after the start of the first conveyance processing. In the second error processing, the CPU  41  performs the error notification. 
     When the print medium M is detected by the first sensor  47  for the period equal to or greater than the predetermined time period, the possibility that the thickness in the up-down direction of the print medium M is thick is higher than when the print medium M is detected by the first sensor  47  for the period less than the predetermined time period. In this case, the printer  1  can improve the printing productivity by performing the first separation processing and the second conveyance processing. On the other hand, when the print medium M is detected by the first sensor  47  for the period less than the predetermined time period, the possibility that the print medium M has the wrinkle is higher than when the print medium M is detected by the first sensor  47  for the period equal to or greater than the predetermined time period. In this case, by performing the second error processing, the printer  1  can suppress the printing from being performed on the print medium M that has the wrinkle. 
     Modifications can be made to the present disclosure from the above-described embodiment. Various modified examples to be described below can be respectively combined insofar as no contradictions arise. For example, in the above-described embodiment, the number of the heads  91  to  96  may be more than six or may be less than six. The printer  1  may discharge various types of ink from the heads  91  to  96 , different from the ink of the above-described embodiment. 
     In the above-described embodiment, the platen  5  is provided to be movable in the up-down direction. In contrast to this, the heads  91  to  96  may be provided to be movable in the up-down direction. In this case, it is sufficient that the printer  1  raise the heads  91  to  96  in the processing from step S 52  to step S 56 , for example, and lower the heads  91  to  96  in the processing at step S 64 . Both the platen  5  and the heads  91  to  96  may be provided to be movable in the up-down direction. 
     In the above-described embodiment, the platen  5  is provided to be movable in the front-rear direction. In contrast to this, the heads  91  to  96  may be provided to be movable in the front-rear direction. In this case, it is sufficient that the printer  1  move the heads  91  to  96  forward in the processing at step S 22 , for example. Both the platen  5  and the heads  91  to  96  may be provided to be movable in the front-rear direction. 
     One or both of the first sensor  47  and the second sensor  48  may be provided at a position different from that of the above-described embodiment. For example, the first sensor  47  and the second sensor  48  may be provided at the same position as each other in the front-rear direction. The second sensor  48  may be provided further to the rear than the first sensor  47 . One or both of the first sensor  47  and the second sensor  48  may be provided further to the rear or further to the front than the front wall  21 . The first sensor  47  is preferably provided further to the rear than the rear end of the platen  5  when the platen  5  is positioned at the set position. In this case, the printer  1  more easily detects the presence or absence of the wrinkle over the whole of the print medium M on the platen  5  from the front end to the rear end of the print medium M, using the first sensor  47 . The first sensor  47  is preferably disposed further to the front than the front end of the head (the head  96  in the above-described embodiment) positioned furthest to the front among the plurality of heads  91  to  96 . In this case, the printer  1  more easily detects, using the first sensor  47 , the presence or absence of the wrinkle in the print medium M on the platen  5  before the print medium M on the platen  5  comes into contact with the heads  91  to  96 , for example. 
     In the above-described embodiment, one or both of the first sensor  47  and the second sensor  48  may measure a distance in the up-down direction between the respective sensor and the print medium M by emitting light downward. The first sensor  47  and the second sensor  48  may detect the print medium M at the first detection position V 1  or at the second detection position V 2  in this way. In this case, the printer  1  may be provided with only one of the first sensor  47  and the second sensor  48 . A type of sensor different from the reflective optical sensor may be employed as one or both of the first sensor  47  and the second sensor  48 . For example, the first sensor  47  and the second sensor  48  may be a transmission type optical sensor, may be an image sensor, or may be a contact sensor. It is sufficient that the image sensor be provided at a position capable of recognizing the upper surface of the print medium M on the platen  5  from the left or from the right. In this case, the CPU  41  performs known filter processing that performs edge extraction on the basis of an image capture result by the image sensor, and identifies a contour (the upper surface) of the print medium M. In this way, the CPU  41  identifies whether or not the print medium M is at the first detection position V 1 . For the contact sensor, when the print medium M on the platen  5  has come into contact with the sensor, for example, the contact sensor detects the print medium M that has made contact. 
     In the above-described embodiment, the CPU  41  sets the first movement distance L 1  and the second movement distance L 2  in accordance with the operation of the input portion  46  by the user. In contrast to this, the first movement distance L 1  and the second movement distance L 2  may be stored in advance in the ROM  42 . In this case, the second movement distance L 2  may be the same as the first movement distance L 1 , may be smaller than the first movement distance L 1 , or may be greater than the first movement distance L 1 . The first movement distance L 1  and the second movement distance L 2  may be the same as the first detection distance D 1 , for example, or may be smaller or greater than the first detection distance D 1 . The first movement distance L 1  and the second movement distance L 2  may be the same as the second detection distance D 2 , for example, or may be smaller or greater than the second detection distance D 2 . 
     In the above-described embodiment, at step S 64 , the CPU  41  raises the platen  5  up to the reference position V 3 . In contrast to this, at step S 64 , the CPU  41  may raise the platen  5  by a third movement distance. The third movement distance may be the same as the first movement distance L 1 , may be smaller or greater than the first movement distance L 1 , may be the same as the second movement distance L 2 , or may be smaller or greater than the second movement distance L 2 . It is sufficient that the third movement distance be stored in advance in the ROM  42 , and the third movement distance may be changed in accordance with an operation of the input portion  46  by the user. 
     In the above-described embodiment, the retry distance L 3  is stored in advance in the ROM  42 . In contrast to this, the CPU  41  may set the retry distance L 3  in accordance with an operation of the input portion  46  by the user. 
     In the above-described embodiment, the first retry control is performed a maximum of two times per each print command. In contrast to this, after the retry number has reached  1 , the CPU  41  may perform third error processing when the print medium M is detected by the first sensor  47 . Also after the retry number has reached  2 , the CPU  41  may move the platen  5  downward when the print medium M is detected by the first sensor  47 . 
     In the above-described embodiment, when the print medium M is detected by the first sensor  47 , and when the print medium M is not detected by the second sensor  48  (hereinafter referred to generically as “when the medium is detected”), the CPU  41  conveys the platen  5  to the front by the retry distance L 3 , at step S 53 , step S 57 , and step S 65 . In other words, in the above-described embodiment, the retry position is the position that is positioned to the front by the retry distance L 3  from the position of the platen  5  when the medium is detected. In contrast to this, when the medium is detected, the CPU  41  may always convey the platen  5  to the same predetermined retry position at step S 53 , step S 57 , and step S 65 , regardless of the position of the platen  5  when the medium is detected. In this case, the retry distance L 3  is not a predetermined distance, but is different depending on the position of the platen  5  when the medium is detected. The retry position when the print medium M is detected by the first sensor  47 , and the retry position when the print medium M is not detected by the second sensor  48  may be mutually different positions. When the medium is detected, the CPU  41  may convey the platen  5  to the set position at step S 53 , step S 57 , and step S 65 . 
     In the above-described embodiment, the CPU  41  acquires the print command by the user operating the input portion  46 , performs the setting in accordance with the first operation or performs the setting in accordance with the second operation. In contrast to this, the CPU  41  may receive various commands from an external device, such as a PC or the like, and may perform processing in accordance with the received command. 
     In the above-described embodiment, the predetermined time period is stored in advance in the ROM  42 . In contrast to this, the CPU  41  may change the length of the predetermined time period in accordance with an operation of the input portion  46  by the user. In this case, the user can set the length of the predetermined time period in accordance with a tolerance of a size of the wrinkle, for example. 
     In the above-described embodiment, the CPU  41  can set ON and OFF for the first retry setting. In contrast to this, the ON and OFF settings for the first retry setting need not necessarily be provided in the printer  1 . In this case, when the print medium M at the first detection position V 1  is detected by the first sensor  47  (yes at step S 24 ), the CPU  41  may determine whether or not the print medium M at the first detection position V 1  is detected by the first sensor  47  for the time period equal to or greater than the predetermined time period (step S 43 ). Similarly, the ON and OFF settings for the second retry setting need not necessarily be provided in the printer  1 . 
     In the above-described embodiment, after lowering the platen  5  at step S 52 , the CPU  41  conveys the platen  5  to the front at step S 53 . In contrast to this, the CPU  41  may convey the platen  5  to the front before starting the lowering of the platen  5  at step S 52 . Furthermore, the CPU  41  may convey the platen  5  to the front while lowering the platen  5 , by starting the conveyance of the platen  5  to the front at the same time as starting the lowering of the platen  5  at step S 52 , for example. Similarly, the printer  1  can also change a processing order of step S 56  and step S 57  and a processing order of step S 64  and step S 65  as necessary. 
     In the above-described embodiment, the CPU  41  may perform the processing at step S 24  and step S 25 , on the basis of the detection signals from the first sensor  47  and the second sensor  48 , during the period of conveying the platen  5  to the retry position at step S 53 , that is, during the period from the start of the processing at step S 53  to the start of the processing at step S 54 . For example, when the platen  5  has not been sufficiently lowered, or when the platen  5  has been excessively lowered, the printer  1  can detect the presence or absence of the print medium M at the first detection position V 1  or the second detection position V 2  more rapidly, compared to when the printer  1  provisionally conveys the platen  5  to the retry position and then performs the processing at step S 24  and step S 25 . 
     In the above-described embodiment, the printer  1  can change, as necessary, the content of the first error processing, the second error processing, the third error processing, and the fourth error processing. For example, in each of the error processing, the CPU  41  may perform the error notification in a state in which the platen  5  is stopped at a current position, without conveying the platen  5  to the set position. In each of the error processing, the CPU  41  may output the error to the external device, such as the PC or the like. In each of the error processing, the CPU  41  may cause the notification portion  45  to perform the error notification using the same notification mode. 
     In the above-described embodiment, an encoder may be provided in the raising/lowering motor  16 . In this case, the CPU  41  may control the position of the platen  5  in the up-down direction by controlling the raising/lowering motor  16  on the basis of a detection result from the encoder. In the above-described embodiment, the printer  1  moves the platen  5  in the up-down direction using the ball screw  38  and the nut  39 . In contrast to this, the printer  1  may move the platen  5  in the up-down direction using another mechanism. Similarly, the printer  1  may move the platen  5  in the front-rear direction using a mechanism different from the above-described embodiment. 
     In the above-described embodiment, the CPU  41  may omit the processing at step S 43  and step S 44 . In other words, when the first retry setting is ON (yes at step S 41 ), the CPU  41  may shift the processing to step S 45 , and may perform the first retry control. 
     In place of the CPU  41 , a microcomputer, application specific integrated circuits (ASICs), a field programmable gate array (FPGA) or the like may be used as a processor. The main processing may be performed as distributed processing by a plurality of the processors. It is sufficient that the non-transitory storage media, such as the ROM  42 , the flash memory  44 , and the like be a storage medium capable of storing information, regardless of a period of storing the information. The non-transitory storage medium need not necessarily include a transitory storage medium (a transmitted signal, for example). The control program may be downloaded from a server connected to a network (not shown in the drawings) (in other words, may be transmitted as transmission signals), and may be stored in the ROM  42  or the flash memory  44 . In this case, the control program may be stored in a non-transitory storage medium, such as an HDD provided in the server. 
     The apparatus and methods described above with reference to the various embodiments are merely examples. It goes without saying that they are not confined to the depicted embodiments. While various features have been described in conjunction with the examples outlined above, various alternatives, modifications, variations, and/or improvements of those features and/or examples may be possible. Accordingly, the examples, as set forth above, are intended to be illustrative. Various changes may be made without departing from the broad spirit and scope of the underlying principles.