JP2005271452A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a throughput of a printer in the case of recording a plurality of color images while wasting of a recording medium and image worsening resulting from load fluctuation during transfer of the recording medium are prevented, and at the same time to smoothly transfer the recording medium. <P>SOLUTION: A pair of rotatively drivable transfer rollers 34 and a pair of sending rollers 35 are arranged at the upper stream side and the lower stream side than a printing part 70 in a transfer direction on a transfer course of a sheet, respectively. The sheet unwound from a sheet feeding part 40 is transferred towards the transfer direction downstream side while the sheet is opposed to thermal heads 71a-73a of the printing part 70 without carrying out printing of the color images. At a time point when the sheet of a length whereby the whole of the plurality of color images included in one order can be printed is transferred to the transfer direction downstream side than the printing part 70, the transfer of the sheet is stopped. Thereafter, the plurality of color images are continuously printed by the thermal heads 71a-73a of the printing part 70 while the paper is sent back towards the transfer direction upstream side by only a transfer force given from the transfer roller pair 34. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a printer that records a color image on a recording medium.

  Various techniques are known for printers capable of recording color images on a recording medium. For example, Patent Document 1 includes three thermal heads capable of individually recording each of yellow, magenta, and cyan colors, and the three recording heads that are drawn from the recording paper roll are conveyed in the paper feeding direction. A one-pass color thermal printer that records a color image with a thermal head is disclosed.

  Patent Document 2 discloses a 3-pass color thermal printer. In such a printer, a color thermal recording paper having a length of one frame drawn from a recording paper roll is sent out so as to face one thermal head, and then a yellow image is recorded while being pulled back, and then the recording paper. Are sent and pulled back alternately, and a magenta image is recorded at the second pull back, and a cyan image is recorded at the third pull back.

Patent Document 3 is provided with three thermal heads of yellow, magenta, and cyan. After the recording paper drawn from the recording paper roll is conveyed in the paper feeding direction and the print preparation is completed, the recording paper is loaded. A one-pass color thermal printer that records a color image of one frame while being conveyed in the pull-back direction is disclosed. In such a printer, when a color image of one frame is recorded, the recording paper is conveyed again in the paper feeding direction and cut at the rear end portion of the color image. Then, the recording paper on which the color image is recorded is discharged, and the next one-frame color image is recorded while the recording paper that has been prepared for printing is conveyed in the pullback direction.
Japanese Patent Application Laid-Open No. 8-174476 JP-A-9-99572 JP 2001-246769 A

  In the printer described in Patent Document 1, a color image can be recorded only by transporting the recording paper in one direction without transporting the recording paper back and forth. However, in such a printer, when the three thermal heads are pressed against the recording paper in order from the one where the recording paper has reached the printing position, the image is deteriorated due to load fluctuations during conveyance of the recording paper. Sometimes. Therefore, in such a printer, in order to prevent the deterioration of the image, the recording of the color image is started after all the three thermal heads are pressed against the recording paper. For this reason, the portion between the thermal head in the vicinity of the leading edge of the recording paper, that is, the length between the most upstream thermal head and the most downstream thermal head in the paper feeding direction from the leading edge of the recording paper is stretched between the thermal heads. Recording of a color image is started. For this reason, there is a problem in that an image is not formed in the length portion where the recording paper is stretched and a blank portion is formed.

  On the other hand, in the printers described in Patent Document 2 and Patent Document 3, a color image can be recorded even in the vicinity of the leading end of the recording paper, so that it is possible to prevent the recording paper from being wasted. Here, in the printer described in Patent Document 3, when the recording paper is conveyed in the pullback direction, all three thermal heads are pressed against the recording paper, so that the image is caused by load fluctuations during the conveyance of the recording paper. Is rarely worse.

  However, in the printer of Patent Document 2, it is necessary to repeat feeding and pulling of the recording paper three times in order to record a single color image. Further, in the printer of Patent Document 3, it is necessary to feed and pull back the recording paper once for each color image of one frame. Therefore, in order to record a color image of a plurality of frames in these printers, the reciprocating conveyance of the recording paper has to be repeated many times.

  Here, in the printers of Patent Document 2 and Patent Document 3, a pair of transport rollers is disposed between the recording paper roll and the thermal head, and the transport direction of the recording paper is switched by switching the driving direction of the pair of transport rollers. Is changed to either the paper feed direction or the pull back direction. Therefore, in order to record a color image of a plurality of m frames (m is an integer of 2 or more), the printer of Patent Document 2 must reciprocate the recording paper 3 m times, and the driving direction of the conveying roller pair is changed. It is necessary to switch only (6m-1) times. In the printer of Patent Document 3, the recording paper must be reciprocated and conveyed m times, and the driving direction of the conveying roller pair needs to be switched only (2m-1) times.

  As described above, when the driving direction of the conveying roller pair is switched, a time-related conveying loss occurs due to the switching. Therefore, if the number of times of switching the driving direction of the conveying roller pair is increased, the time-related conveying loss is increased accordingly, and the processing capability of the printer is lowered.

  Further, when the recording paper is transported, the recording paper is disposed between the paper feeding roll and the image forming unit when the transporting length of the recording paper to the downstream side of the image forming unit is relatively long in the paper feeding direction. If the recording paper is conveyed only by the conveying roller, the recording paper is likely to be jammed in the conveying path. Therefore, it may be difficult to smoothly convey the recording paper.

  Accordingly, a main object of the present invention is to improve the processing capability when recording a plurality of color images while preventing image deterioration due to waste of the recording medium and load fluctuation during conveyance of the recording medium, and recording. It is an object of the present invention to provide a printer that can smoothly convey a medium.

Means and effects for solving the problems

  The printer according to the present invention includes an image recording unit capable of recording a color image on a recording medium, a supply unit storing a long recording medium, and the image recording from the supply unit while the recording medium faces the image recording unit. A transport mechanism capable of transporting in a first direction toward the portion and a second direction opposite to the first direction, and a position where the leading end of the recording medium is separated from the image recording portion in the first direction The recording medium is transported in the second direction by the transport mechanism, and a transport control means for controlling the transport mechanism so that the recording medium is transported in the second direction after being transported in the first direction until reaching Image recording control means for controlling the image recording unit so that a plurality of color images are recorded by the image recording unit on the recording medium, and the transport mechanism includes the supply unit and the image Between the recording section A first roller pair capable of imparting a conveying force to the recording medium by rotating while sandwiching the recording medium, and a conveying force to the recording medium by rotating while sandwiching the recording medium on the downstream side of the image recording unit. And a second roller pair capable of providing

  Note that “the leading end of the recording medium reaches a position away from the image recording unit in the first direction” means that “the recording medium is conveyed in the first direction from the supply unit to the image recording unit and recorded. This means that the leading end of the medium reaches a position downstream of the image recording unit. In this specification, “upstream side” and “downstream side” relate to a first direction from the supply unit toward the image recording unit.

  According to this configuration, a plurality of color images can be recorded on the recording medium conveyed in the second direction after the recording medium is conveyed in the first direction from the supply unit toward the image recording unit. Therefore, a color image can be recorded in the vicinity of the leading end of the recording medium (the region from the leading end of the recording medium portion that is transported in the second direction after being transported in the first direction) and the recording medium is being transported. It is possible to prevent the image from deteriorating due to the load fluctuation. Further, even when a plurality of color images are recorded on the recording medium, it is only necessary to reciprocate the recording medium once, and it is only necessary to switch the conveying direction of the recording medium in the conveying mechanism once. Transport loss can be reduced. As a result, when recording a plurality of color images on a recording medium, it is possible to improve the processing capability of the printer while preventing image deterioration due to waste of the recording medium and load fluctuations during conveyance of the recording medium.

  The first roller pair is disposed between the supply unit and the image recording unit, and the second roller pair is disposed on the downstream side of the image recording unit. Therefore, even when the conveyance length of the recording medium downstream from the image recording unit is relatively long, the recording medium can be smoothly conveyed.

  The printer of the present invention further includes a first rotational force transmission mechanism that idles the first pair of rollers when driven and rotated by the force received from the recording medium, and the conveyance control means includes: When the recording medium is conveyed in the first direction and the leading edge of the recording medium reaches the second roller pair, the second roller pair determined by the drive rotation speed of the second roller pair. It is preferable that the transport mechanism is controlled so that the transport speed of the recording medium is faster than the transport speed of the recording medium by the first roller pair determined by the drive rotation speed of the first roller pair.

  According to this configuration, the recording medium conveyance speed by the first roller pair determined by the driving rotation speed of the first roller pair and the recording medium by the second roller pair determined by the driving rotation speed of the second roller pair The recording medium is not damaged due to the slack of the recording medium generated between the first roller pair and the second roller pair due to the variation in the conveyance speed of the recording medium or the excessive tension applied to the recording medium. Absent. Therefore, the recording medium can be conveyed while applying an appropriate tension, and the recording medium can be conveyed more smoothly in the first direction.

  In the printer according to the aspect of the invention, the conveyance control unit may be configured such that when the recording medium is conveyed in the first direction and the leading end of the recording medium reaches the second roller pair, It is preferable not to drive the roller pair. According to this configuration, power for driving each roller pair can be reduced, and the cost can be reduced.

  The printer of the present invention further includes a second rotational force transmission mechanism that idles the second pair of rollers when driven and rotated by the force received from the recording medium. When transported in the second direction, the transport speed of the recording medium by the first roller pair determined by the driving speed of the first roller pair is determined by the driving speed of the second roller pair. It is preferable to control the transport mechanism so as to be faster than the transport speed of the recording medium by the second roller pair determined.

  According to this configuration, the recording medium conveyance speed by the first roller pair determined by the driving rotation speed of the first roller pair and the recording medium by the second roller pair determined by the driving rotation speed of the second roller pair The recording medium is not damaged due to the slack of the recording medium generated between the first roller pair and the second roller pair due to the variation in the conveyance speed of the recording medium or the excessive tension applied to the recording medium. Absent. Therefore, the recording medium can be conveyed while applying an appropriate tension, and the recording medium can be more smoothly conveyed in the second direction. Further, by smoothly transporting the recording medium in the second direction, the image quality of the image recorded by the image recording unit can be improved.

  In the printer according to the aspect of the invention, it is preferable that the conveyance control unit does not drive the second roller pair when the recording medium is conveyed in the second direction. According to this configuration, power for driving each roller pair can be reduced, and the cost can be reduced.

  The printer according to the present invention includes a leading edge detection unit capable of detecting a leading edge of a recording medium between the first roller pair and the image recording unit, and a rotational speed detection capable of detecting the rotational speed of the first roller pair. And the conveyance direction of the recording medium from the first direction to the second direction based on the number of rotations detected by the rotation number detection unit after the leading end of the recording medium is detected by the leading end detection unit It is preferable that the apparatus further includes a detecting unit that detects the conveyance length of the recording medium conveyed downstream from the image recording unit before the change.

  According to this configuration, the conveyance length of the recording medium conveyed downstream from the image recording unit can be detected based on the conveyance amount of the recording medium conveyed downstream from the detection position by the leading edge detection unit. it can. Therefore, only the recording medium having a length necessary for recording a plurality of color images is transported in the first direction before the transport direction of the recording medium is changed from the first direction to the second direction. Can do. As a result, it is possible to suppress a decrease in the processing capability of the printer by transporting an extra length of recording medium that is not necessary for recording a plurality of color images in the first direction.

  Further, even when the recording medium is transported in the first direction and the leading end of the recording medium reaches the second roller pair, the transport amount of the recording medium transported in the first direction is Detection is based on the number of rotations of one roller pair. As a result, the conveyance due to variations in the roller diameter of each roller pair that occurs when the conveyance amount of the recording medium is detected based on the rotation speed of the first roller pair and the rotation speed of the second roller pair. The amount detection error can be eliminated.

  In the printer of the present invention, it is preferable that the first roller pair is formed of metal. According to this configuration, since the roller diameter of the first roller pair hardly changes due to wear or the like, the conveyance amount of the recording medium conveyed in the first direction can be accurately detected.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of a printer according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of a printing unit of the printer of FIG. FIG. 3 is a diagram illustrating the movement of the conveying roller pair and the feeding roller pair of the printer of FIG. FIG. 4 is a block diagram of a main part of the printer of FIG. 1 and a control device to which these are connected.

  A thermal sublimation thermal printer 1 shown in FIG. 1 (hereinafter referred to as “printer 1”) includes an operation unit 10, a control device 20, and a printing unit 30. The operation unit 10 is for an operator to operate the printer 1 and has a display 11 for displaying various information about the printer 1 and notifying the operator. Here, in the present embodiment, a touch panel method is adopted for the operation unit 10, and an operation screen 12 including various buttons is displayed on the display 10. Accordingly, the operator can execute an operation on the printer 1 by touching the operation screen 12.

  The control device 20 receives input from the operation unit 10 and controls various operations in the printer 1. In addition, the control device 20 has a plurality of data input units 20a for acquiring print data from various storage media such as a card slot and a disk drive. The storage medium may be any medium that can store print data, such as a CD-ROM or a memory card.

  Here, the operation unit 10 and the control device 20 are fixedly arranged on the upper surface of the housing 30 a that houses the print unit 30. Here, the display surface of the display 11 of the operation unit 10 and the storage medium insertion surface of the data input unit 20a of the control device 20 substantially coincide with the front of the printer 1 (housing 30a) (the surface on the left front side in FIG. 1). ing. Therefore, it is easy for the operator heading to the front of the printer 1 to operate the display 11 and the data input unit 21.

  Moreover, the housing | casing 30a has a substantially rectangular parallelepiped shape, The horizontal width (front width) D1 is smaller than the depth D2. Therefore, the printer 1 can be installed even in a relatively narrow space.

  As shown in FIG. 2, the print unit 30 includes a paper supply unit 40 that holds a paper wound in a roll shape and a paper winding unit that winds up the paper that has been unwound from the paper supply unit 40. Between the take-up unit 80 and the paper supply unit 40 and the paper take-up unit 80, there is a transport mechanism 38 that can transport the paper along a transport path curved in one direction. A cutting unit 50, an overcoat unit 60, and a printing unit 70 are disposed between the paper supply unit 40 and the paper winding unit 80 from the upstream side to the downstream side of the transport path. In addition, a discharge unit 95 is provided in the vicinity of the conveyance path between the paper supply unit 40 and the cutting unit 50.

  In the present embodiment, “paper transport direction (transport direction)” means a direction from the paper supply unit 40 toward the paper winding unit 80. Further, the “paper front end” and the “image front end” mean the end on the downstream side of the paper or the image transport direction, and the “paper rear end” and “image rear end” The term “edge” means an end portion on the upstream side of the sheet or image in the conveying direction.

  The paper supply unit 40 has a magazine case 41 provided in the uppermost stream of the transport path, and a long paper is wound around the rotation shaft 43 so that the printing surface is outside. The wound winding part 45 is loaded. Here, the rotating shaft 43 is driven to rotate counterclockwise in FIG. 2 when the sheet is unwound from the sheet supply unit 40 and conveyed toward the downstream side in the conveying direction by the motor 43a (see FIG. 4). When the unwound paper is taken up by the paper supply unit 40, it is rotated clockwise in FIG. The rotary shaft 43 is connected to a shaft (not shown) that is rotationally driven by a motor 43a via a one-way clutch 43c having the same function as one-way clutches 34c and 35c described later.

  The transport mechanism 38 is arranged in order from the upstream side in the transport direction, and includes a pair of paper feed rollers 31 that can transport the paper unrolled from the winding unit 45 of the paper supply unit 40 upward, and the cutting unit 50. Also, a turn roller pair 32 that is arranged on the upstream side in the transport direction and changes the transport direction of the paper transported upward, and a pressure roller pair that can sandwich the paper between the cutting unit 50 and the overcoat unit 60. 33 and a pair of transport rollers 34 capable of transporting the paper, and a paper which is disposed downstream of the printing unit 70 in the transport direction and transported downstream of the printing unit 70 in the transport direction. A feed roller pair 35 for feeding the inside is provided. In this embodiment, the paper feed roller pair 31, the turn roller pair 32, the pressure roller pair 33, and the feed roller pair 35 are made of resin rollers, and the transport roller pair 34 is made of a metal roller. Has been.

  Here, the pair of feed rollers 31, the pair of turn rollers 32, the pair of pressure rollers 33, the pair of transport rollers 34 and the pair of feed rollers 35 are arranged on a circumference having a predetermined radius (indicated by a two-dot chain line in FIG. 2). It is arranged along. As can be seen from FIG. 2, the head portions 61 and 71 to 73 of the overcoat portion 60 and the printing portion 70 are also arranged along the circumference, and the paper supply portion 40 and the paper take-up portion 80 are It arrange | positions inside the said periphery.

  The paper feed roller pair 31, the transport roller pair 34, and the feed roller pair 35 are connected to motors 31a, 34a, and 35a (see FIG. 4) controlled by the transport control unit 27a (see FIG. 4), respectively, and are rotationally driven. Is possible.

  Here, the movement of the transport roller pair 34 and the feed roller pair 35 will be described in detail with reference to FIG. FIG. 3A shows the movement of the transport roller pair 34 and the feed roller pair 35 when the paper is transported downstream in the transport direction, and FIG. 3B shows that the paper is upstream in the transport direction. The movement of the conveying roller pair 34 and the feeding roller pair 35 during reverse feeding is shown. As shown in FIG. 3, the conveyance roller pair 34 includes a driving roller 34d and a driven roller 34e. The drive roller 34d is connected to a shaft 34b that is rotationally driven by a motor 34a via a one-way clutch 34c. Similarly, the feed roller pair 35 includes a drive roller 35d and a driven roller 35e, and the drive roller 35d is connected to a shaft 35b that is rotationally driven by a motor 35a via a one-way clutch 35c.

  Since the one-way clutches 34c and 35c have the same function, the function of the one-way clutch 34c will be described here. The one-way clutch 34c is fixed to the driving roller 34d and rotates together with the driving roller 34d. When the drive roller 34d rotates faster than the rotational speed of the shaft 34b, the rotational force of the shaft 34b is not transmitted to the drive roller 34d, and the drive roller 35d rotates idly with respect to the shaft 34b. In other cases, the rotational force of the shaft 34b is transmitted to the drive roller 34d via the one-way clutch 34c, and the shaft 34b and the drive roller 34d rotate together.

  Therefore, when the conveyance roller pair 34 holds the sheet, the conveyance speed of the sheet is slower than the conveyance speed of the sheet based on the rotational force of the conveyance roller pair 34 driven by the motor 34a. Is transmitted to the conveying roller pair 34. Then, the sheet is transported with a transport force applied by the transport roller pair 34. On the other hand, when the paper conveyance speed is faster than the paper conveyance speed based on the rotational force of the conveyance roller pair 34 driven by the motor 34a, the driving force of the motor 34a is not transmitted to the conveyance roller pair 34 and is conveyed. The roller pair 34 is idle. That is, the transport roller pair 34 is driven to rotate at a rotational speed corresponding to the paper transport speed.

  Here, the sheet conveying speed based on the rotational force of the conveying roller pair 34 driven by the motor 34a is V1, and the sheet conveying speed based on the rotational force of the feeding roller pair 34 driven by the motor 35a is V2. Consider the case of transporting a sheet downstream in the transport direction with reference to (a). At this time, as will be described later, after the leading edge of the paper reaches the feed roller pair 35 and is nipped, the drive of the transport roller pair 34 is stopped, and the transport speed V1 becomes zero. On the other hand, the feed roller pair 35 is rotationally driven by the driving force of the motor 35a being transmitted through the shaft 35b and the one-way clutch 35c. Since the sheet sandwiched between the transport roller pair 34 is transported at the transport speed V2, the transport roller pair 34 is idled by the function of the one-way clutch 34c.

  Next, with reference to FIG. 3B, consider a case where the paper is fed back upstream in the transport direction. At this time, as will be described later, since the driving of the feed roller pair 35 is stopped, the conveyance speed V2 becomes zero. On the other hand, the conveying roller pair 34 is rotationally driven by the driving force of the motor 34a being transmitted through the shaft 34b and the one-way clutch 34c. Since the sheet sandwiched between the feed roller pair 35 is reversely fed at the conveyance speed V1, the feed roller pair 35 rotates idly by the function of the one-way clutch 35c.

  The pair of paper feed rollers 31 is also connected to a shaft (not shown) that is rotationally driven by a motor 31a via a one-way clutch 31c having the same function as the one-way clutches 34c and 35c described above. Accordingly, the paper feed roller pair 31, the transport roller pair 34, and the feed roller pair 35 are configured to remove the paper unrolled from the paper supply unit 40 by individually controlling the motors 31a, 34a, and 35a by the transport control unit 27a. The sheet can be conveyed downstream in the conveying direction and taken up by the paper take-up unit 80, and the paper once taken up in the paper take-up unit 80 can be unwound and unwound from the paper take-up unit 80. The printed paper can be fed back toward the upstream side in the transport direction.

  Further, the printing unit 30 includes an encoder 36 that can detect the number of rotations of the conveyance roller pair 34. Here, as described above, the transport roller pair 34 is driven and rotated by the motor 34a to transport the paper, and is driven and rotated along with the paper transported by the feed roller pair 35. obtain. The encoder 36 can detect the number of rotations of the conveyance roller pair 34 even when the conveyance roller 34 is in any of the above states.

  The cutting part 50 is disposed between the turn roller pair 32 and the pressure roller pair 33. The cutting unit 50 includes a rolling cutter 51 disposed above the conveyance path, a fixed blade 52 disposed below the conveyance path, and a chip box 53.

  The rolling cutter 51 has a disk shape, and a blade is formed on the entire circumference of the rolling cutter 51. The center of the rolling cutter 51 is held by a shaft 51a. The rolling cutter 51 is connected to a drive mechanism 55 (see FIG. 4) controlled by the cutting control unit 27c via a shaft 51a. The drive mechanism 55 rotates and drives the rolling cutter 51 via the shaft 51a, and moves forward or backward along the sheet conveyance path along a direction orthogonal to the sheet (in the direction orthogonal to the paper surface in FIG. 2). . On the other hand, the fixed blade 52 is a rectangular blade that is disposed so as to be orthogonal to the paper transport path and is longer than the entire width of the paper transport path.

  Therefore, when the cutting control unit 27c controls the drive mechanism 55 and moves the rolling cutter 51 along the width direction of the paper while rotating the paper while the paper is arranged at the cutting position by the cutting unit 50, the rolling cutter The sheet is cut by the interaction between 51 and the fixed blade 52. In the printer 1 according to the present embodiment, as will be described later, the cutting unit 50 cuts the paper at the leading edge and the trailing edge of each image.

  The chip box 53 is disposed below the rolling cutter 51 and the fixed blade 52. Accordingly, when the paper is cut at the leading edge or the trailing edge of each image and the blank portion between the images is cut, the blank portion is stored in the chip box 53.

  The overcoat unit 60 is disposed on the downstream side of the conveyance roller pair 34 in the conveyance direction. The overcoat part 60 has one head part 61. The head unit 61 is for performing a colorless and transparent overcoat (OC) on the surface of the paper on which an image is printed. Thus, by overcoating the surface of the paper, the light resistance of the image printed on the paper can be improved and the surface of the paper can be protected. Further, by selecting the material of the overcoat, the gloss of the print can be improved and a high-quality print can be provided.

  The printing unit 70 is disposed between the overcoat unit 60 and the feed roller pair 35. The printing unit 70 has three head units 71 to 73. The head portions 71 to 73 are for performing printing corresponding to cyan (C), magenta (M), and yellow (Y), respectively. Here, in the printer 1, a head unit 71 corresponding to cyan, a head unit 72 corresponding to magenta, and a head unit 73 corresponding to yellow are provided in this order from the upstream side in the transport direction to the downstream side in the transport direction. In the printer 1, the transport roller pair 34 is disposed on the upstream side in the transport direction of the overcoat unit 60 and the printing unit 70, and the feed roller pair 35 is disposed on the downstream side in the transport direction.

  In the printer 1 of the present embodiment, when the paper unrolled from the paper supply unit 40 is conveyed toward the downstream side in the conveyance direction, the overcoat in the overcoat unit 60 and the color image in the printing unit 70 are performed. Is not performed, and when the paper once wound on the paper take-up unit 80 disposed on the downstream side in the transport direction from the print unit 70 is fed back toward the upstream side in the transport direction, the print unit 70 The printing of the image at and the overcoat at the overcoat unit 60 are performed. Accordingly, the printer 1 can print a color image in the order of yellow, magenta, and cyan on the paper surface, and can further overcoat the paper surface on which the color image is printed.

  Next, a schematic configuration of the head units 61 and 71 to 73 will be described. In addition, since the structure of the head parts 61 and 71 to 73 is the same, only the head part 73 will be described in detail here.

  The head unit 73 includes a thermal head 73a having a large number of heating elements (not shown) arranged over the entire width of the paper conveyance path, and a tip portion of the thermal head 73a (in the vicinity of the paper conveyance path and the heating elements are arranged). A platen roller 73b facing the other end, a tape-like ribbon 73c having an ink area to which ink corresponding to yellow is attached, a ribbon supply roller 73d around which a ribbon 73c before printing is wound, and a post-printing ribbon A ribbon take-up roller 73e for taking up the ribbon 73c.

  Here, the thermal head 73a can be moved back and forth with respect to the paper transport path by an elevating mechanism 73f (see FIG. 4). Therefore, the thermal head 73a can selectively take the print position where the ribbon 73c and the paper are pressed against each other and the retracted position where the paper 73 is not pressed between the vicinity of the tip and the platen roller 73b.

  In the head unit 73, when the paper is conveyed between the thermal head 73a and the platen roller 73b in a state where the thermal head 73a is disposed at the printing position, the ink of the ribbon 73c heated by the thermal head 73a. Thus, a color image corresponding to yellow can be printed on the paper. At this time, when the sheet is conveyed between the thermal head 73a and the platen roller 73b, the ribbon 73c is also moved from the ribbon supply roller 73d toward the ribbon take-up roller 73e as the sheet is conveyed. Sent.

  The head unit 61 and the head units 71 and 72 are similar to the head unit 73 in that the thermal heads 61a, 71a, 72a, the platen rollers 61b, 71b, 72b, the ribbons 61c, 71c, 72c, and the ribbon supply roller 61d. 71d, 72d, ribbon take-up rollers 61e, 71e, 72e, and elevating mechanisms 61f, 71f, 72f, respectively.

  Here, in the head unit 61 and the head units 71 and 72, ink corresponding to colorless and transparent, cyan and magenta, respectively, instead of the tape-like ribbon 73c having an ink region to which ink corresponding to yellow of the head unit 73 is attached. Tape-shaped ribbons 61c, 71c, and 72c having an ink region to which are attached are used.

  A pair of guides 75 a to 75 c are arranged between the head portion 61 of the overcoat portion 60 and the head portions 71 to 73 of the printing portion 70, respectively. Each of the pair of guides 75a to 75c includes two plate-like members, and guides the sheet (mainly the leading end of the sheet) conveyed between the head units 61 and 71 to 73, respectively. is there. Accordingly, the pair of guides 75a to 75c are arranged so as to face each other with a predetermined interval across the sheet conveyance path.

  The paper take-up unit 80 has a storage case 81 provided on the most downstream side of the transport path. The storage case 81 has a substantially cylindrical shape, and a part of the storage case 81 opens as a paper insertion opening 82. In the present embodiment, as shown in FIG. 2, the central angle of the portion that becomes the insertion port 82 is about 90 degrees, and one edge 82a is in the vicinity of the left end of the storage case 81, and the other The edge portion 82 b is in the vicinity of the upper end portion of the storage case 81.

  Here, the feeding roller pair 35 is disposed in the vicinity of the upper portion of the edge portion 82 a of the storage case 81, and the sheet conveyed downward by the feeding roller pair 35 is located in the storage case 81 from the vicinity of the end portion 82 a of the insertion port 82. Inserted into. The paper inserted into the paper winding unit 80 is guided by contacting the inner peripheral surface of the storage case 81. As a result, in the storage case 81, the paper is wound in order from the leading edge of the paper so that the printing surface becomes the outer surface according to the curl of the paper. The storage case 81 is rotatably provided with four winding rollers 83a to 83d. A part of each of the winding rollers 83 a to 83 d protrudes inward from the inner peripheral surface of the storage case 81. Accordingly, since the frictional force when the paper comes into contact with the inner peripheral surface of the storage case 81 is reduced, the paper is prevented from being damaged.

  The discharge unit 95 discharges a sheet (print) on which each color image printed by the cutting unit 50 is printed after the printing of the image in the printing unit 70 and the overcoat in the overcoat unit 60 is performed. Is. The discharge unit 95 includes a print box 96 that stores printed paper. The print box 96 is a box-like member having an upper end opened, and is supported by a support shaft 97 at the lower end so as to be rotatable. Accordingly, the print box 96 is housed in the housing 30a (shown by a solid line in FIG. 2) and the vicinity of the upper end portion is pulled out from the front surface (right surface in FIG. 2) of the housing 30a (FIG. 2). The state indicated by the broken line in FIG. Therefore, the operator can easily take out the paper on which each color image is printed by pulling out the upper end portion of the print box 96 from the front of the printer 1 (housing 30a).

  A sorting mechanism (not shown) is provided in the vicinity of the upper end portion of the discharge unit 95 so as to be closer to the transport path upstream of the turn roller pair 32 in the transport direction. In this sorting mechanism, the paper is fed back toward the upstream side in the transport direction when the paper is wound around the paper supply unit 40 and when the paper on which each color image is printed is discharged to the print box 96. It is possible to switch the paper transport path when printing. Therefore, by controlling the sorting mechanism, only the paper on which each color image is printed can be stored in the print box 96.

  Further, an image detection sensor 90 that can detect an end portion (mainly a rear end portion of the image) of an image printed on a sheet conveyed along the conveyance path, on the upstream side of the cutting unit 50 in the conveyance direction. Is provided. On the other hand, a paper detection sensor 91 that can detect the edge of the paper is provided upstream of the overcoat unit 60 in the transport direction. In the present embodiment, the end of the overcoat unit 60 on the upstream side in the conveyance direction and the detection position by the paper detection sensor 91 substantially coincide.

  As shown in FIG. 4, the control device 20 includes a motor 43 a that drives the rotation shaft 43 of the paper supply unit 40, a motor 31 a that drives the paper feed roller pair 31, the transport roller pair 34, and the feed roller pair 35, respectively. 34a, 35a, an encoder 36 for detecting the rotation speed of the conveying roller pair 34, a driving mechanism 55 for the rolling cutter 51 of the cutting unit 50, and the thermal heads 61a, 71a to 73a of the overcoat unit 60 and the printing unit 70. The mechanisms 61f and 71f to 73f and the drivers 61g and 71g to 73g, the image detection sensor 90, the paper detection sensor 91, and the operation unit 10 are respectively connected.

  The control device 20 includes hardware such as a CPU, a ROM, and a RAM controlled by appropriate software, and includes a maximum winding amount storage unit 21, a print information storage unit 22, and a necessary winding amount calculation unit. 23, a comparison unit 24, a winding amount determination unit 25, a conveyance amount detection unit 26, a conveyance control unit 27a, a print control unit 27b, and a cutting control unit 27c.

  The maximum winding amount storage unit 21 maximizes the maximum length of paper that can be transported downstream in the transport direction from the printing unit 70 when the paper is transported from the paper supply unit 40 toward the paper winding unit 80. It is memorized as a winding amount. The maximum winding amount is determined by the length of the conveyance path between the printing position by the head unit 73 arranged on the most downstream side in the conveyance direction of the printing unit 70 and the insertion port 82 of the sheet winding unit 80, and the sheet winding. This value is calculated by adding together the length of paper that can be taken up in the storage case 81 of the unit 80. The maximum winding amount is input to the maximum winding amount storage unit 21 by the operator.

  Here, the maximum winding amount largely varies depending on the size of the storage case 81. The length of paper that can be wound in the storage case 81 may be the maximum length of paper that can actually be stored in the storage case 81, or the maximum length of paper that can be stored in the storage case 81. It may be shorter than the length and can be set arbitrarily. Therefore, in the present embodiment, the length of the paper that can be wound in the storage case 81 used when the maximum winding amount is calculated is that the paper is not damaged or scratched in the storage case 81. The length of the range is set to be shorter than the maximum length of paper that can be stored in the storage case 81.

  The print information storage unit 22 stores various setting values when a color image is printed. Here, the set values include the print length of one frame for each print type (the length in the transport direction), the number of prints (the number of frames), the length of the margin formed between adjacent images, and the head heat dissipation. Includes additional length. As the print length of one frame for each print type, a plurality of values are stored for each of a plurality of print types such as a standard size and a panorama size. As the number of prints, a value input for each order by the operator before printing is stored. Further, the length of the margin between the images and the additional length for heat radiation of the head are stored as values input by the operator before starting printing.

  The necessary winding amount calculation unit 23 calculates the length of paper necessary for printing all of a plurality of color images included in one order as the necessary winding amount. In other words, in order to print all of a plurality of color images included in one order, before the printing of the color image by the printing unit 70, paper having a length capable of printing these color images is printed on the printing unit. It is necessary to carry the sheet downstream in the carrying direction from 70. Therefore, when the paper is conveyed from the paper supply unit 40 toward the paper take-up unit 80, the printing position by the head unit 73 of the printing unit 70 is used to print all of the plurality of color images included in one order. The length of the paper to be transported exceeding this is calculated as the required winding amount.

  Here, the necessary winding amount will be described with reference to FIG. FIG. 5 is a diagram illustrating a state in which a plurality of color images included in one order are printed in the vicinity of the leading edge of the paper. Note that FIG. 5 illustrates a case where six images of the same print type are included in one order. As shown in FIG. 5, a region corresponding to the additional length z for heat radiation of the head is provided near the leading end (left end portion in FIG. 5) of the sheet, and from there toward the upstream side (right side in FIG. 5) The area corresponding to the print length x and the area corresponding to the margin length y are alternately provided by the number n of prints.

Accordingly, in the necessary winding amount calculation unit 23, when the print type and the number of prints of a color image included in one order are input by the operator before starting printing, each value stored in the print information storage unit 22 is set. Based on this, the required winding amount L corresponding to one order is calculated by the following equation.
L = z + x * n + y * (n-1)

  The comparison unit 24 compares the required winding amount calculated by the required winding amount calculation unit 23 with the maximum winding amount stored in the maximum winding amount storage unit 21. Then, the comparison unit 24 obtains a comparison result regarding the magnitude relationship between the required winding amount and the maximum winding amount.

  The winding amount determination unit 25 is actually transported downstream of the printing unit 70 in the transport direction before the sheet transport direction is changed from the direction toward the downstream side in the transport direction to the direction toward the upstream side in the transport direction. The length of the sheet (actual winding amount), that is, the length of the sheet that is actually conveyed beyond the position facing the head unit 73 of the printing unit 70 is determined. Here, the winding amount determination unit 25 determines the winding amount based on the comparison result by the comparison unit 24. That is, when the comparison unit 24 obtains a comparison result that the required winding amount is equal to or less than the maximum winding amount, the winding amount determination unit 25 determines the actual winding amount as the necessary winding amount, On the other hand, when the comparison unit 24 obtains a comparison result that the required winding amount is longer than the maximum winding amount, the actual winding amount is determined as the maximum winding amount.

  The carry amount detection unit 26 detects the carry amount of the paper based on the number of rotations of the carry roller pair 34 detected by the encoder 36 after the leading edge of the paper is detected by the paper detection sensor 91. That is, the transport amount detection unit 26 detects the length of the paper transported downstream in the transport direction from the position detected by the paper detection sensor 91. As a result, the transport amount detection unit 26 is transported downstream of the printing unit 70 in the transport direction before the sheet transport direction is changed from the direction toward the downstream side in the transport direction to the direction toward the upstream side in the transport direction. The length of the paper can be detected. As will be described later, after the leading edge of the sheet reaches the feed roller pair 35, the sheet is transported by the transport force applied from the feed roller pair 35 instead of the transport force applied from the transport roller pair 34. However, even in this case, the carry amount detection unit 26 always detects the carry amount of the paper based on the number of rotations of the carry roller pair 34.

  The conveyance amount detection unit 26 can detect the conveyance amount of the paper not only when the paper is conveyed toward the downstream side in the conveyance direction but also when the paper is conveyed toward the upstream side in the conveyance direction. . Therefore, when the paper transport direction is changed from the direction downstream in the transport direction to the direction upstream in the transport direction, the transport direction is changed from the transport amount downstream in the transport direction before the transport direction is changed. The leading end position of the sheet can be detected by subtracting the transport amount upstream in the transport direction after being performed.

  The conveyance control unit 27a controls the motors 43a, 31a, 34a, and 35a that drive the rotation shaft 43, the paper feed roller pair 31, the conveyance roller pair 34, and the feeding roller pair 35, thereby supplying the paper from the paper supply unit 40 to the paper. The sheet is conveyed toward the winding unit 80 and the sheet is fed back from the sheet winding unit 80 toward the sheet supply unit 40.

  Here, the function of the conveyance control unit 27a will be described in more detail. First, when the sheet is conveyed toward the downstream side in the conveyance direction, the driving of the motor 34a is stopped and the rotation shaft is stopped until the leading edge of the sheet passes through the conveyance roller pair 34 and reaches the sheet detection sensor 91. The motors 43a and 31a are controlled so that the paper transport speed based on the rotational force of the paper feed roller pair 31 is faster than the paper feed speed based on the rotational force 43. At this time, due to the functions of the one-way clutches 43c, 31c, and 34c, the rotating shaft 43 and the conveyance roller pair 34 are idle, and the paper feed roller pair 31 is driven by the motor 31a. Accordingly, the sheet is transported by the transport force applied from the pair of sheet feed rollers 31.

  Thereafter, the motors 43a and 31a are stopped driving until only the motor 34a is driven until the leading edge of the sheet is nipped by the feed roller pair 35. At this time, due to the functions of the one-way clutches 43c, 31c, and 34c, the rotating shaft 43 and the paper feed roller pair 31 are idle, and the transport roller pair 34 is driven by the motor 34a. Accordingly, the sheet is transported only by the transport force applied from the transport roller pair 34.

  When the leading edge of the sheet is sandwiched between the feed roller pair 35, the motors 43a, 31a and 34a are stopped and only the motor 35a is driven. At this time, due to the functions of the one-way clutches 43c, 31c, 34c, and 35c, the rotary shaft 43, the paper feed roller pair 31, and the transport roller pair 34 are idle, and the feed roller pair 35 is driven by the motor 35a. Accordingly, the sheet is transported only by the transport force applied from the transport roller pair 35.

  Further, when the paper is fed back toward the upstream side in the transport direction, the driving of the motor 35a is stopped until the rear end portion of the color image printed on the most upstream side in the transport direction of the paper is cut. The motor 43a is configured such that the sheet rewinding speed based on the rotational force of the rotating shaft 43, the paper conveying speed based on the rotational force of the paper feed roller pair 31, and the paper conveying speed based on the rotational force of the conveying roller pair 34 are equal. , 31a, 34a are controlled. At this time, due to the functions of the one-way clutches 43c, 31c, 34c, and 35c, the rotating shaft 43, the paper feed roller pair 31, and the transport roller pair 34 are driven by the motors 43a, 31a, and 34a, respectively, and the feed roller pair 35 rotates idle. Therefore, the sheet is fed back by the conveying force applied from the rotating shaft 43, the sheet feeding roller pair 31 and the conveying roller pair 34.

  Then, after the trailing edge of the color image printed on the most upstream side in the transport direction of the paper is cut, the paper is rewound based on the rotational force of the rotary shaft 43 and the paper is based on the rotational force of the paper feed roller pair 31. By controlling the motors 43a and 31a so that the conveyance speeds of the two are equal, the function of the one-way clutches 43c and 31c allows the rotation shaft 43 and the paper feed roller pair 31 to be driven by the motors 43a and 31a, and the conveyance direction. The paper upstream of the cutting position is rewound to the paper supply unit 40. Further, by driving the motor 34a and stopping the driving of the motor 35a, the transport roller pair 34 is driven by the motor 34a and the feed roller pair 35 is idled by the function of the one-way clutches 34c and 35c. Accordingly, the sheet on the downstream side of the cutting position in the transport direction is reversely fed only by the transport force applied from the transport roller pair 34.

  The printing control unit 27b controls the raising / lowering timing and printing timing of the thermal head 61a of the overcoat unit 60 and the thermal heads 71a to 73a of the printing unit 70. The cutting control unit 27 c controls the cutting timing at the cutting unit 50.

  Next, the operation when the printer 1 prints an image will be described with reference to FIG. FIG. 6 is a flowchart showing an operation procedure in the printer 1.

  First, the leading end of the sheet unwound by rotating the rotary shaft 43 from the paper winding unit 45 loaded in the paper supply unit 40 is transported only by the transport force applied from the paper feed roller pair 31. (Step S101). Then, the conveyance by the paper feed roller pair 31 is continued until the leading edge of the paper passes through the conveyance roller pair 34 and reaches the paper detection sensor 91 (step S102). Here, when the leading edge of the sheet is detected by the sheet detection sensor 91, a detection signal indicating that the leading edge of the sheet has been detected is transmitted from the sheet detection sensor 91 to the control device 20.

  In this way, when the leading edge of the paper reaches the paper detection sensor 91, the conveyance of the paper is stopped and a standby state is entered (step S103). At this time, if the thermal heads 61a and 71a to 73a are arranged at the print positions, the thermal heads 61a and 71a to 73a are moved to the retracted positions (step S104).

  Thereafter, when an order is received from the operator and the print type and the number of prints of color images included in one order are input (step S105), the print information is stored as preparation for starting the conveyance of the paper. Based on the information stored in the unit 22, the necessary winding amount corresponding to the one order is calculated by the necessary winding amount calculation unit 23 (step S106). Then, the required winding amount is compared with the maximum winding amount stored in the maximum winding amount storage unit 21 by the comparison unit 24 (step S107). Based on the comparison result, the winding amount determination unit 25 determines the actual winding amount (step S108). In this way, after completion of the sheet conveyance preparation, the sheet is conveyed only by the conveyance force applied from the conveyance roller pair 34 (step S109). At this time, both the rotation shaft 43 and the paper feed roller pair 31 of the paper supply unit 40 are rotatable.

  Thereafter, in a state in which the thermal heads 61a and 71a to 73a are disposed at the retracted positions, the leading end of the sheet passes through the overcoat unit 60 and the print unit 70 without performing overcoat and image printing, and the feed roller The conveyance is continued only by the conveyance force applied from the conveyance roller pair 34 until the pair 35 is reached (step S110). When the leading edge of the sheet reaches the nipping roller pair 35 and is nipped, the sheet is thereafter conveyed only by the conveying force applied from the feeding roller pair 35 and is wound from the leading edge of the sheet. Are sequentially fed into the storage case 81 of the unit 80 (step S111). At this time, as the paper is fed into the storage case 81, the leading edge of the paper is guided to the inner peripheral surface of the storage case 81 and the take-up rollers 83 a to 83 d, and the paper is wound around the curl in the storage case 81. Therefore, it is wound up. When the leading edge of the paper reaches the feed roller pair 35, the transport roller pair 34 is accompanied by the paper transported by the feed roller pair 35 from the state in which the transport force is applied to the paper by the function of the one-way clutch 34c. It is switched to the state of driven rotation.

  Thereafter, when the sheet having the length of the winding amount determined by the winding amount determination unit 25 is conveyed downstream in the conveyance direction from the printing position by the head unit 73, the winding of the sheet is finished, The conveyance of the sheet from the sheet supply unit 40 toward the sheet winding unit 80 is stopped (step S112). That is, the conveyance amount of the paper detected by the conveyance amount detection unit 26 based on the number of rotations of the conveyance roller pair 34 detected by the encoder 36 after the leading edge of the paper is detected by the paper detection sensor 91 is taken up. When the winding amount determined by the amount determination unit 25 and the length of the conveyance path in the overcoat unit 60 and the printing unit 70 are added, the conveyance control unit 27a finishes winding the sheet. Then, the conveyance of the sheet to the downstream side in the conveyance direction is stopped. At this time, the rear end portion of the image printed on the most upstream side in the transport direction of the sheet having the winding amount is disposed at the printing position by the head unit 73.

  Then, the thermal head 61a of the overcoat unit 60 and the thermal heads 71a to 73a of the printing unit 70 are simultaneously moved from the retracted position to the printing position (step S113). Thereafter, the sheet is fed back toward the upstream side in the transport direction by the transport force applied from the pair of paper feed rollers 31 and the pair of transport rollers 34 (step S114). Accordingly, at this time, the pair of paper feed rollers 31 and the pair of transport rollers 34 that have been driven to rotate are rotationally driven in the direction of transporting paper toward the upstream side in the transport direction, and the pair of feed rollers 35 The function of the clutch 35c causes the driven rotation. Further, the rotation shaft 43 of the paper supply unit 40 is rotationally driven in a direction to rewind the paper into the magazine case 41.

  Then, while the paper is being fed back toward the upstream side in the transport direction, for each color image included in one order, printing corresponding to yellow is performed by the head unit 73, printing corresponding to magenta is performed by the head unit 72, and printing is performed by the head unit 71. Printing corresponding to cyan is sequentially performed. In this way, each color image is printed in the order of yellow, magenta, and cyan, thereby completing the color image (step S115). After that, the head unit 61 continues to overcoat the surface of the paper on which the color image is printed (step S116).

  In the present embodiment, a plurality of color images included in one order are printed intermittently so that a margin portion having a predetermined width is formed between the images. In other words, as described above, after an area corresponding to the additional length for heat radiation of the head is arranged in the vicinity of the leading end of the sheet, the image area and the margin are alternately arranged. And in the printing part 70, when there exists an image area | region at the same timing in the position facing at least 2 of the three head parts 71-73, printing is simultaneously performed by those head parts. In addition, the overcoat in the overcoat unit 60 is performed in parallel with the printing of the color image in the print unit 70. In this way, in the printing unit 70 and the overcoat unit 60, a plurality of printable sheets can be printed on the paper having the winding amount determined by the winding amount determination unit 25 or the paper having the maximum winding amount. The color image is printed and overcoated.

  The trailing end of the color image printed on the most upstream side in the transport direction (corresponding to the trailing end of the sheet having the winding amount determined by the winding amount determination unit 25) is formed by the cutting unit 50. When the cutting position is reached, the reverse feeding of the paper is stopped, and the paper is cut at the rear end portion of the color image (step S117). Note that the timing at which the trailing edge of the color image reaches the cutting position by the cutting unit 50 is detected based on the carry amount detected by the carry amount detection unit 26. Then, after the paper is cut in this way, the paper on which the image upstream of the most upstream color image in the transport direction is not formed (the length of the winding amount determined by the winding amount determination unit 25). The sheet upstream of the trailing edge of the sheet in the transport direction) is rewound to the sheet supply unit 40.

  Subsequently, when the sheet is reversely fed only by the conveyance force applied from the conveyance roller pair 34 and the rear end portion of the image on the most upstream side in the conveyance direction reaches the detection position by the image detection sensor 90, the image detection sensor 90 controls the control device. A detection signal indicating that the rear end of the image has been detected is transmitted to 20 (step S118). Then, after the trailing edge of the image is detected by the image detection sensor 90, the conveyance amount detection unit 26 determines that the leading end of the color image is a cutting unit based on the number of rotations of the conveyance roller pair 34 detected by the encoder 36. It is detected that the cutting position by 50 has been reached. At this time, the reverse feeding of the paper is stopped, and the paper is cut at the leading end of the color image (step S119).

  In this way, each time the paper is cut at the leading edge of the color image, whether the color image printed on the cut paper is the final image printed closest to the leading edge of the paper or not. Is determined (step S120). Here, if it is determined that the image is not the final image, the paper is reversely fed again. Then, after the paper is cut at the leading end of the color image, the carry amount detection unit 26 cuts the leading end at step S119 based on the number of rotations of the carry roller pair 34 detected by the encoder 36. It is detected that the rear end portion of the color image adjacent to the color image on the downstream side in the transport direction has reached the cutting position by the cutting portion 50. At this time, the reverse feeding of the paper is stopped, and the paper is cut at the rear end portion of the color image (step S121). Then, it returns to step S118 and the process similar to the above is repeated.

  On the other hand, if it is determined that the image is the final image, it is determined whether or not printing of all color images included in one order has been completed (step S122). If it is determined that printing of all the color images included in one order has not been completed, the process returns to step S106 and the same processing as described above is repeated. On the other hand, when it is determined that all the printing of the color images included in one order has been completed, the process ends.

  Note that the case where it is determined in step S122 that all printing of color images included in one order has not been completed means that, for example, the comparison unit 24 determines that the necessary winding amount is longer than the maximum winding amount. This is a case where the winding amount determination unit 25 determines the maximum winding amount as the final winding amount. That is, in this case, printing of the remaining color images that could not be printed on the sheet having the maximum winding amount among the color images included in one order is continued. In this way, the same processing as described above is repeated until all the printing of the color images included in one order is completed.

  As described above, in the printer 1 according to the present embodiment, after the paper is transported in the direction from the paper supply unit 40 to the paper winding unit 80, the upstream side in the transport direction from the overcoat unit 60 and the printing unit 70. A plurality of color images can be printed on a sheet that is reversely fed toward the upstream side in the conveyance direction by a conveyance force applied from the arranged conveyance roller pair 34. For this reason, it is possible to print a color image in an area from the front end of the paper portion that is reversely fed after conveyance, and it is possible to suppress deterioration of the image due to load fluctuations during conveyance of the paper. Further, even when printing a plurality of color images on paper, it is only necessary to reciprocate the paper once, and it is only necessary to switch the paper transport direction in the transport mechanism 38 once. Loss can be reduced. As a result, when printing a plurality of color images on paper, the processing capability of the printer 1 can be improved while preventing image deterioration due to paper waste and load fluctuations during paper transport.

  Further, a pair of transport rollers 34 capable of transporting paper is disposed between the paper supply unit 40 and the printing unit 70 on the transport path, and feed rollers for feeding the paper into the paper take-up unit 80. The pair 35 is disposed downstream of the printing unit 70 in the transport direction. Therefore, even when the paper take-up amount determined by the take-up amount determination unit 25 is relatively long, the paper can be smoothly conveyed and fed into the paper take-up unit 80.

  Further, when the paper is transported downstream in the transport direction, after the leading edge of the paper reaches the feed roller pair 35 and is sandwiched, the paper is transported only by the transport force applied from the feed roller pair 35 and is fed. The paper roller pair 31 and the transport roller pair 34 are controlled to be driven to rotate at a rotational speed corresponding to the paper transport speed. On the other hand, when the paper is transported backward toward the upstream side in the transport direction, the transport speed of the paper based on each rotational force until the trailing edge of the color image printed on the most upstream side in the transport direction is cut. The paper is reversely fed by the conveyance force applied from the paper feed roller pair 31 and the conveyance roller 34 pair controlled so as to be equal to each other, and the feed roller pair 35 is driven to rotate at a rotation speed corresponding to the paper conveyance speed. Controlled. Thereafter, the sheet on the downstream side of the cutting position in the transport direction is reversely fed only by the transport force applied from the pair of transport rollers 34, and the feed roller pair 35 is driven to rotate at a rotational speed corresponding to the transport speed of the sheet. Controlled. Therefore, the paper is damaged due to the slack of the paper that occurs on the paper transport path due to variations in the paper transport speed based on the rotational force of each roller pair 31, 34, and 35, and the application of excessive tension to the paper. There is nothing. Therefore, the sheet can be conveyed while applying an appropriate tension, and the sheet can be more smoothly conveyed downstream in the conveyance direction. Thereby, the image quality of the color image printed in the printing part 70 can be improved.

  In addition, when the paper is transported downstream in the transport direction, after the leading end of the paper passes through the transport roller pair 34 and reaches the paper detection sensor 91, the rotation shaft 43 and the paper feed roller pair 31 are driven. Is stopped, and after the leading edge of the paper reaches the feed roller pair 35 and is nipped, the driving of the transport roller pair 34 is further stopped. On the other hand, when the sheet is fed backward toward the upstream side in the transport direction, the driving of the feed roller pair 35 is stopped. Therefore, it is possible to reduce the power for driving the rotating shaft 43, the paper feed roller pair 31, the transport roller pair 34, and the feed roller pair 35, and to reduce the cost.

  Further, the length of the sheet conveyed downstream in the conveyance direction from the printing unit 70 can be detected based on the conveyance amount of the sheet conveyed downstream in the conveyance direction from the detection position by the sheet detection sensor 91. . Therefore, before the paper transport direction is changed from the direction toward the downstream side in the transport direction to the direction toward the upstream side in the transport direction, only the paper having a length necessary for printing a plurality of color images is downstream in the transport direction. It can be conveyed toward. As a result, it is possible to suppress a decrease in processing capacity of the printer 1 by transporting an extra length of paper that is not necessary for printing a plurality of color images toward the downstream side in the transport direction. .

  Further, when the paper is transported downstream in the transport direction, the transport amount of the paper transported downstream in the transport direction is equal to the transport roller pair even after the leading edge of the paper reaches the feed roller pair 35 and is nipped. 34 based on the number of rotations. Thus, when detecting the conveyance amount of the sheet based on the rotation number of the conveyance roller pair 34 and the rotation number of the feeding roller pair 35, the detection error of the conveyance amount caused by the variation in the roller diameter of each roller pair is eliminated. It can be lost.

  Further, the conveying roller pair 34 is composed of a metal roller. Therefore, since the roller diameter of the transport roller pair 34 hardly changes due to wear or the like, the transport amount of the paper transported downstream in the transport direction can be accurately detected.

  The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and various design changes can be made as long as they are described in the claims. It is a thing. For example, in the above-described embodiment, the rotating shaft 43, the paper feed roller pair 31, the transport roller pair 34, and the feed roller pair 35 are respectively connected to the motors 43a, 31a, and 31c via the one-way clutches 43c, 31c, 34c, and 35c. Although the case where it has connected with 34a, 35a was demonstrated, it is not restricted to this. The one-way clutches 43c, 31c, 34c, and 35c may be omitted. Further, the one-way clutches 43c, 31c, 34c, and 35c may be replaced with other parts having the same function.

  Furthermore, in the above-described embodiment, an example of control of the motors 43a, 31a, 34a, and 35a for driving the rotation shaft 43, the pair of paper feed rollers 31, the pair of transport rollers 34, and the pair of feed rollers 35 by the transport control unit 27a, respectively. The control of the motors 43a, 31a, 34a, and 35a can be changed within a range in which the same effect as in the present embodiment can be obtained. Therefore, control may be performed so that the paper is transported by the transport force applied from any of the roller pairs 31, 34, and 35.

  In the above-described embodiment, when the paper is transported downstream in the transport direction, after the leading end of the paper passes through the transport roller pair 34 and reaches the paper detection sensor 91, the rotation shaft 43 and the paper supply are performed. After the drive of the paper roller pair 31 is stopped and the leading edge of the paper reaches the feed roller pair 35 and is nipped, the drive of the transport roller pair 34 is further stopped to reverse the paper toward the upstream side in the transport direction. Although the case where the driving of the feeding roller pair 35 is stopped when feeding is described, it is not limited to this. For example, the rotation shaft 43, the paper feed roller pair 31, the transport roller pair 34, and the feed roller pair 35 may be always driven.

  In the above-described embodiment, when the sheet is conveyed downstream in the conveyance direction, the conveyance force applied from the feed roller pair 35 is also used when the sheet is conveyed only by the conveyance force applied from the conveyance roller pair 34. Even in the case where the sheet is conveyed only by the conveyance amount detection unit 26, the case where the conveyance amount of the sheet is always detected based on the number of rotations of the conveyance roller pair 34 has been described, but the present invention is not limited thereto. For example, when the roller pair that applies the conveying force to the sheet is switched from the conveying roller pair 34 to the feeding roller pair 35, the sheet conveyance amount is also detected by the rotation of the feeding roller pair 35 based on the number of rotations of the conveying roller pair 34. It may be performed by switching to a number.

  In addition, in the above-described embodiment, the case where the transport roller pair 34 is configured by a metal roller has been described. However, the present invention is not limited to this. The conveyance roller pair 34 may be composed of a resin roller.

  Further, in the above-described embodiment, the conveyance amount detection unit 26 detects the conveyance amount of the paper based on the rotation number of the conveyance roller pair 34 detected by the encoder 36 after the paper detection sensor 91 detects the leading edge of the paper. However, the transport amount detection unit 26 may detect the transport amount of the paper by other methods.

  In the above-described embodiment, an area corresponding to the additional length for heat radiation of the head is provided in the vicinity of the leading end of the paper, and a plurality of color images are printed while a blank portion is formed between the images. The region corresponding to the additional length for heat radiation of the head may not be provided, and a blank portion may not be formed between the images.

  Furthermore, in the above-described embodiment, in the thermal sublimation printer 1, a color image is printed by the three head portions 71 to 73 that come into contact with the paper that is the recording medium. If there is, the configuration of the image recording unit is not limited to this. Therefore, it may be a thermal printer (including a thermal transfer system and a thermal recording system) having a head that comes into contact with a recording medium, and has, for example, an inkjet head, a FOCRT (Fiber Optic Cathode-Ray-Tube), a laser light source, etc. The printer may be capable of recording a color image without contacting the recording medium. Further, the image recording unit does not necessarily have a plurality of image recording heads, and may have only one image recording head capable of recording a color image. Therefore, for example, it has three inkjet heads each having nozzles capable of ejecting yellow, magenta and cyan inks, and these heads reciprocate in a direction crossing the recording medium conveyance direction to record a color image. Or a single inkjet head having nozzles capable of discharging yellow, magenta, and cyan inks, and the head reciprocates in a direction intersecting the recording medium conveyance direction. It may be a printer that records color images.

1 is an external perspective view of a printer according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of an image forming unit of the printer of FIG. 1. It is a figure showing a motion of the conveyance roller pair of the printer of FIG. 1, and a sending roller pair. It is a block diagram about the principal part of the printer of FIG. 1, and the control apparatus to which these were connected. It is a figure which shows a mode when the several color image contained in 1 order is printed in the front-end | tip part vicinity of a paper. 3 is a flowchart showing an operation procedure in the printer 1.

Explanation of symbols

1 Thermal printer (printer)
DESCRIPTION OF SYMBOLS 10 Operation part 20 Control apparatus 21 Maximum winding amount memory | storage part 22 Print information storage part 23 Required winding amount calculation part 24 Comparison part 25 Winding amount determination part 26 Conveyance amount detection part (detection means)
27a Transport control unit (transport control means)
27b Print control unit (image recording control means)
27c Cutting control unit 30 Printing unit 34 Conveying roller pair (first roller pair)
35 Feed roller pair (second roller pair)
34c, 35c one-way clutch (first rotational force transmission mechanism, second rotational force transmission mechanism)
36 Encoder (Rotation speed detection means)
38 Transport mechanism 40 Paper supply unit (supply unit)
50 Cutting unit 60 Overcoat unit 70 Printing unit (image recording unit)
71a to 73a Thermal head 80 Paper winding unit 91 Paper detection sensor (tip detection means)
95 Discharge section

Claims (7)

An image recording unit capable of recording a color image on a recording medium;
A supply unit storing a long recording medium;
A transport mechanism capable of transporting a recording medium in a first direction from the supply unit toward the image recording unit and a second direction opposite to the first direction while facing the image recording unit;
The transport mechanism so that the recording medium is transported in the second direction after being transported in the first direction until the leading end of the recording medium reaches a position away from the image recording unit in the first direction. Transport control means for controlling
Image recording control means for controlling the image recording unit so that a plurality of color images are recorded by the image recording unit on a recording medium conveyed in the second direction by the conveyance mechanism;
The transport mechanism is
A first roller pair capable of imparting a conveying force to the recording medium by rotating while sandwiching the recording medium between the supply unit and the image recording unit;
A printer having a second roller pair capable of imparting a conveyance force to a recording medium by rotating while sandwiching the recording medium on the downstream side of the image recording unit. A first rotational force transmission mechanism that idles the first roller pair when driven and rotated by a force received from the recording medium;
The conveyance control unit is configured to drive the rotational speed of the second roller pair after the recording medium is conveyed in the first direction and the leading edge of the recording medium reaches the second roller pair. The conveyance speed of the recording medium determined by the second roller pair is set to be higher than the conveyance speed of the recording medium determined by the first roller pair determined by the driving rotation speed of the first roller pair. The printer according to claim 1, wherein the mechanism is controlled.   The conveyance control means does not drive the first roller pair after the recording medium is conveyed in the first direction and the leading edge of the recording medium reaches the second roller pair. The printer according to claim 2. A second rotational force transmission mechanism that idles the second roller pair when driven and rotated by a force received from the recording medium;
When the recording medium is transported in the second direction, the transport control means is configured such that the transport speed of the recording medium by the first roller pair determined by the driving rotational speed of the first roller pair is the first speed. 4. The conveyance mechanism according to claim 1, wherein the conveyance mechanism is controlled so as to be faster than a conveyance speed of the recording medium by the second roller pair determined by the number of rotations of the second roller pair. Printer.   The printer according to claim 4, wherein the conveyance control unit does not drive the second roller pair when the recording medium is conveyed in the second direction. A leading edge detecting means capable of detecting a leading edge of a recording medium between the first roller pair and the image recording unit;
A rotational speed detection means capable of detecting the rotational speed of the first roller pair;
The conveyance direction of the recording medium is changed from the first direction to the second direction based on the rotational speed detected by the rotational speed detection means after the leading edge of the recording medium is detected by the leading edge detection means. 6. The apparatus according to claim 1, further comprising a detection unit that detects a conveyance length of the recording medium conveyed downstream from the image recording unit. Printer.   The printer according to claim 6, wherein the first roller pair is made of metal.

Images