JP2011084021A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent attachment of ink of an ink ribbon on a printing face of a paper sheet for perfecting printing. <P>SOLUTION: By turning a body part 66 around a support shaft 90b by pressing a drive cam 68a to a cam follower 91 by rotation of a drive motor 69, the position of a printing head 62 is changed to a retreated position from the printing position. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  Conventionally, there has been known an image forming apparatus which prints an image on a printing surface of paper and prints additional information such as a frame number, a shooting date, correction data of color and density performed at a photo shop on the back surface of the paper. (For example, refer to Patent Document 1).

  In Patent Document 1, incidental information is printed using a dot impact type back surface printing apparatus. This back surface printing apparatus includes an ink ribbon cassette containing an ink ribbon and a print head that presses the ink ribbon. The print head includes a plurality of needle pins. By reciprocating the needle pins in the axial direction, the ink ribbon is pressed against the back surface of the paper to transfer the ink.

JP 2005-271459 A

  However, in the conventional image forming apparatus, since the print head is disposed close to the paper transport path, ink on the ink ribbon may adhere to the back surface of the paper and become soiled during paper transport. Specifically, if the ink ribbon has a wrinkle in the ink ribbon cassette, the ink ribbon is bent so as to be exposed to the paper conveyance path side from the opening of the ink ribbon cassette, and the bent portion of the ink ribbon and the paper And the ink adheres.

  Here, as in the image forming apparatus of Patent Document 1, if the apparatus has a development process, even if ink adheres to the back surface of the paper, the ink ribbon and the paper are in contact with each other. Ink is not particularly problematic because it is washed away during immersion and transport into the developing solution.

  However, in an image forming apparatus that is not immersed in a developing solution, particularly when printing is performed on both sides of paper, the ink of the ink ribbon adheres to the printing surface of the paper and becomes dirty, resulting in poor print quality. Therefore, it is not preferable.

  The present invention has been made in view of this point, and an object thereof is to prevent ink ribbon ink from adhering to the printing surface of a paper on which double-sided printing is performed.

  In order to achieve the above-described object, the present invention enables the print head to be retracted from the transport path when it is not necessary to perform back side printing, such as when performing duplex printing on paper.

  Specifically, the present invention is directed to an image forming apparatus including a back surface printing unit that transfers an ink by pressing an ink ribbon carrying ink on the back surface of a paper printing surface. I took it.

That is, in the first invention, the back surface printing means is
A print head for pressing the ink ribbon;
Position change means for changing the position of the print head to a print position that can be printed on the back surface of the paper in the vicinity of the paper conveyance path and a retreat position that is retreated from the paper conveyance path. It is characterized by being.

  In the first invention, the back surface printing unit includes a print head that presses the ink ribbon, and a position changing unit that changes the position of the print head. The position changing means changes the position of the print head between a print position where printing can be performed on the back surface of the paper in the vicinity of the paper transport path and a retreat position retracted from the paper transport path.

  With such a configuration, when printing is performed on both sides of the paper, it is possible to prevent the ink ribbon ink from adhering to the printing surface of the paper. Specifically, in the dot impact type back surface printing apparatus, since the print head is arranged so as to be close to the paper conveyance path, the ink ribbon is curled in the ink ribbon cassette and exposed to the paper conveyance path side. In such a case, the ink of the ink ribbon may adhere to the back surface of the paper when the paper is transported. In particular, when printing is performed on both sides of the paper, there is a problem that the ink adheres to the printing surface and becomes dirty, resulting in a decrease in printing quality.

  On the other hand, in the present invention, the position of the print head can be changed between a print position that can be printed on the back surface of the paper in the vicinity of the paper conveyance path and a retreat position that is retreated from the paper conveyance path. Therefore, when there is no need to print additional information on the back side of the paper, such as paper that performs double-sided printing, the ink of the ink ribbon adheres to the back side of the paper by retracting the print head to the retracted position. This can be prevented.

According to a second invention, in the first invention,
The position changing unit is configured to change the position of the print head from the printing position to the retracted position based on double-sided printing information indicating that double-sided printing is performed on the paper. Is.

  In the second invention, the position of the print head is changed from the print position to the retracted position by the position changing unit based on the double-sided printing information indicating that double-sided printing is performed on the paper. With such a configuration, the print head is retracted from the print position by allowing the operator to input double-sided printing information indicating that printing is to be performed on both sides of the paper, or by automatically determining on the device side. Can be moved to. This can reliably prevent the ink ribbon ink from adhering to the printing surface of the paper on which double-sided printing is performed.

According to a third invention, in the first or second invention,
A support shaft extending in the width direction of the paper;
A cam follower disposed below the support shaft;
A main body that accommodates the print head and is rotatably supported with respect to the support shaft;
The position changing means includes a drive cam provided in the main body so as to correspond to the cam follower, and a drive motor that rotationally drives the drive cam, and the drive cam is rotated by the drive motor. The position of the print head is changed from the print position to the retracted position by pressing the cam follower and rotating the main body about the support shaft. .

  In a third aspect of the present invention, a support shaft that extends in the width direction of the paper, a cam follower disposed below the support shaft, and a main body that is rotatably supported with respect to the support shaft are provided. A print head is accommodated in the main body. The position changing means includes a drive cam provided in the main body so as to correspond to the cam follower, and a drive motor that rotationally drives the drive cam. The drive cam is pressed against the cam follower by the rotational drive of the drive motor. As a result, the main body is rotated around the support shaft, and the position of the print head is changed from the print position to the retracted position.

  With such a configuration, the print head can be moved from the print position to the retracted position simply by rotating the drive cam, and the ink of the ink ribbon adheres to the print surface of the paper on which double-sided printing is performed. This can be prevented.

  According to the present invention, the position of the print head can be changed between a print position that can be printed on the back side of the paper in the vicinity of the paper transport path and a retreat position that is retracted from the paper transport path. Therefore, when there is no need to print incidental information on the back side of the paper, such as paper that performs double-sided printing, the ink ribbon ink adheres to the back side of the paper by retracting the print head to the retracted position. Can be prevented.

1 is a perspective view illustrating an appearance of an ink jet printer according to an embodiment of the present invention. It is the schematic seen from the side which shows the internal structure of an inkjet printer. It is a side view which shows the state in which the opening part of the magazine was closed. It is a side view which shows the state by which the opening part of the magazine was opened. It is a top view which shows the structure of the platen of a printing part. It is a side view which shows the structure of a printing part and a cap part. It is the schematic which shows the state which the switchback roller pair of a switchback part is receiving the paper conveyed from the conveyance roller pair. FIG. 8 is a view corresponding to FIG. 7 showing a state in which the driven rollers of the switchback roller pair are switched to the second position. It is a perspective view which shows the structure of a back surface printing apparatus. It is a side view which shows the state before attaching a back surface printing apparatus in a housing | casing. FIG. 11 is a view corresponding to FIG. 10 illustrating a state where the back surface printing apparatus is positioned at a printing position. FIG. 11 is a view corresponding to FIG. 10 illustrating a state in which the back surface printing apparatus is positioned at the retracted position.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

  FIG. 1 is a perspective view showing an external appearance of an ink jet printer as an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic side view showing an internal configuration of the ink jet printer.

  As shown in FIGS. 1 and 2, the inkjet printer A is used in a photo print system, and communicates from a reception block (not shown) that acquires image data and performs necessary correction processing, for example. Printing is performed on the paper P based on image data transmitted via a cable.

  The inkjet printer A includes a printer main body 1 having a casing 2 having a caster 3 provided on the lower surface. Two magazines M that can accommodate a long paper P wound in a roll shape are accommodated side by side in the vertical direction in the lower part of the housing 2 of the printer body 1. The paper P is accommodated in a storage chamber S inside the magazine M, and the surface facing the radially outer side when it is wound in a roll shape is a printing surface.

  In the present embodiment, the side (left side in FIG. 2) where the manual feed tray 7 is attached in the printer main body 1 is referred to as the printer front side, and the opposite side (right side in FIG. 2) is referred to as the printer rear side. 2 is the left-right direction of the printer and coincides with the width direction of the paper P conveyed in the printer main body 1.

  The magazine M is a substantially hermetically sealed box-shaped container configured to be portable. In the storage chamber S inside the magazine M, paper P wound in a roll shape around the core 5 is stored. An opening 11 for drawing out the paper P accommodated in the magazine M to the outside of the magazine M is formed at the front end of the upper surface of the magazine M. The opening 11 has a substantially rectangular shape extending in the same direction as the core 5.

  The magazine M is provided with a magazine roller 12 that feeds the paper P out of the storage chamber S through the opening 11. The paper P sent out by the magazine roller 12 is delivered to a supply roller 24 described later.

  The magazine M is provided with a holding roller pair 13 that holds the paper P drawn from the core 5 in the magazine M between the opening 11 and the magazine roller 12. The pair of holding rollers 13 sandwiches the leading end portion of the paper P in the magazine M. This restricts the leading end of the paper P from freely moving in the magazine M, and prevents the paper P from being loosened or the printing surface from rubbing against the bottom surface in the magazine M. .

  FIG. 3 is a side view showing a state in which the opening of the magazine is closed. As shown in FIG. 3, the opening 11 of the magazine M is provided with an opening / closing shutter mechanism 20 for opening and closing the opening 11. The opening / closing shutter mechanism 20 can switch between a guide plate 14 that guides the paper P drawn from the core 5 to the opening 11, a state where the paper P is pressed against the guide plate 14, and a state where the pressure is released. A shutter roller 15 and a cam mechanism 16 for driving the shutter roller 15 are provided.

  The shutter roller 15 opens and closes the opening 11 to block or allow the air flow in the magazine M. The shaft 15a extends along the opening 11 of the magazine M, and the outer peripheral portion of the shaft 15a. And a roller portion 15b that is pressure-bonded to the guide plate 14. The shutter roller 15 is slidably supported by long holes 20a formed in the left and right side walls near the opening 11 of the magazine M. The shaft portion 15 a of the shutter roller 15 is constantly urged toward the guide plate 14 by an urging spring (not shown) and is in contact with the front end portion of the slide plate 17 constituting a part of the cam mechanism 16.

  The cam mechanism 16 includes a slide plate 17 and an eccentric cam 18 driven by a motor (not shown). The slide plate 17 is formed with two long holes 17a extending in the longitudinal direction of the magazine. Two guide shafts 17b projecting outward from the left and right side walls of the magazine M are respectively inserted into the long holes 17a of the slide plate 17, and the slide plate 17 is supported by the guide shafts 17b. As a result, the slide plate 17 is slidable in the longitudinal direction of the magazine while being supported by the guide shaft 17b.

  A substantially rectangular cam hole 17c is formed at the end of the slide plate 17 on the rear side of the magazine. The inner peripheral surface of the cam hole 17 c constitutes a contact surface that contacts the cam surface of the eccentric cam 18. The eccentric cam 18 is attached eccentrically with respect to the output shaft 18a of the motor. Further, a detection piece 18b is provided on the output shaft 18a of the motor, and the origin position of the motor is detected by the detection sensors 19 attached to the left and right side walls of the magazine M.

  Next, the operation of the opening / closing shutter mechanism 20 will be specifically described. First, in the press-bonded state shown in FIG. 3 (the state where the opening 11 is closed), the eccentric portion of the eccentric cam 18 is located on the rear side of the magazine M with respect to the motor output shaft 18a. When the eccentric cam 18 is rotated clockwise in FIG. 3, the eccentric portion of the eccentric cam 18 is positioned on the front side of the magazine M with respect to the output shaft 18a of the motor (see FIG. 4). At this time, the cam hole 17c of the slide plate 17 is pressed to the magazine front side by the eccentric cam 18, and the slide plate 17 moves to the magazine front side along the guide shaft 17b.

  As a result, the shutter roller 15 moves to the front side of the magazine against the urging force of the urging spring while being pressed by the tip of the slide plate 17. As a result, a gap is generated between the roller portion 15b of the shutter roller 15 and the guide plate 14, and the opening portion 11 is opened.

  With such a configuration, the opening 11 can be forcibly opened by rotating the eccentric cam 18 of the open / close shutter mechanism 20 and moving the shutter roller 15 only during the operation of the inkjet printer A. Therefore, the air in the magazine M can be prevented from drying by being left for a long time with the opening 11 of the magazine M open, and the paper P in the magazine M can be protected from cracks and the like. .

  As shown in FIG. 2, the magazine M is placed on a slide base 10 slidable in the front-rear direction of the housing 2. The slide table 10 is configured to be slidable in the front-rear direction of the apparatus by linear guides (not shown) provided on the left and right sides in the housing 2 and extending in the front-rear direction of the apparatus. The magazine M can be taken in and out of the housing 2. The front surface of the slide table 10 is part of the housing 2 and is covered with a door member 10a that can be opened and closed, and the paper P can be replaced by opening the door member 10a. Can be done.

  In the upper part of the housing 2 (above the upper magazine M), a printing surface of the paper P drawn out from the storage chamber S of the magazine M, or a single-cut paper ( A printing unit 21 that performs printing based on image data is provided on a printing surface (not shown).

  Here, a guide member 28 for guiding the paper P to the printing unit 21 is disposed between the magazine M and the printing unit 21. The guide member 28 is for preventing the leading end portion of the paper P from being displaced from the conveyance path when the paper P moves toward the supply roller 24 of the printing unit 21 through the conveyance path. On the upstream side of the guide member 28, a first branch passage 28a and a second branch passage 28b branched into two are provided. The paper P drawn from the lower magazine M is inserted into the first branch passage 28a, and the paper P drawn from the upper magazine M is inserted into the second branch passage 28b. As a result, the papers P of the magazines M accommodated so as to be lined up and down are finally joined together and guided to the supply roller 24 through different transport paths.

  Further, between the guide member 28 and the magazine M, a reflective first sensor 40 and a second sensor 41 for detecting that the front end of the paper P is pulled out from the magazine M are disposed.

  A manual feed tray 7 is provided on the front upper portion of the printer main body 1 for an operator to manually feed a sheet of paper. The manual feed tray 7 can be accommodated in a folded state in the housing 2 as shown in FIG. 1 when not in use.

  A manual feed roller pair 9 is disposed on the rear side of the printer with respect to the manual feed tray 7. The manual feed roller pair 9 includes a driving roller 9a that comes into contact with a printing surface of the printing unit 21 in paper, and a driven roller 9b that comes into contact with a surface opposite to the printing surface. The drive roller 9a is driven by a motor (not shown). Then, the paper supplied to the manual feed tray 7 is sent out toward the supply roller 24 by the rotation of the manual feed roller pair 9.

  In the inkjet printer A according to the present embodiment, printing can be performed using the paper P stored in the storage chamber S of the magazine M and the sheet-like paper manually supplied to the manual feed tray 7 by the operator. However, the processing for each paper after being supplied to the printing unit 21 is the same. Therefore, in the following, a case where printing is performed by transporting the paper P accommodated in the magazine M will be mainly described.

  As shown in FIG. 2, the paper P fed out of the magazine by the magazine roller 12 is supplied to the printing unit 21 by the supply roller 24. Specifically, the paper P is sandwiched between a supply roller 24 and two pressure rollers 24a disposed opposite to the supply roller 24, and the supply roller 24 is rotated clockwise by a drive motor (not shown). It is conveyed to the printing unit 21 by being driven.

  The supply roller 24 is rotated in the forward direction by which the paper P is pulled out from the storage chamber S of the magazine M and conveyed to the printing unit 21 side by the drive motor, and in the reverse direction to return the paper P into the storage chamber S. It is configured as possible. Thereby, for example, when printing on the paper P is interrupted and the sheet-like paper inserted into the manual feed tray 7 or the paper P in the other magazine M is supplied to the printing unit 21 for printing. The paper P existing on the transport path can be returned into the magazine M. Further, when the paper P is replaced with a new one, the paper P drawn into the printer main body 1 can be returned to the magazine M.

  A printing unit 21 that performs printing based on image data is provided on the downstream side of the supply roller 24. The printing unit 21 includes a print head H that prints on the printing surface of the paper P, and a platen 23 that supports the paper P conveyed from the supply roller 24.

  On the downstream side of the print head H, a pressure-bonding downstream roller pair 25 including a driving roller 25a disposed below the conveying path and a driven roller 25b positioned above the driving roller 25a is disposed. . The drive roller 25a is driven by a motor (not shown).

  On the downstream side of the supply roller 24, a third sensor 42 (consisting of a light projecting part and a light receiving part) for detecting the leading edge of the paper P sent out from the supply roller 24 is disposed. From the detection of the leading edge of the paper P by the third sensor 42, when the paper P is conveyed by the supply roller 24 by an amount such that the print start portion of the paper P reaches the lower position of the print head H, Start printing. Further, from the detection of the leading edge of the paper P by the third sensor 42, when the paper P is conveyed by the supply roller 24 by such an amount that the leading edge of the paper P reaches the downstream roller pair 25, the supply roller 24 is crimped. From the state, the pressure release state is set and the downstream roller pair 25 is changed from the pressure release state to the pressure bonded state, and the paper P is conveyed by the downstream roller pair 25 this time.

  FIG. 5 is a plan view illustrating the configuration of the platen of the printing unit, and FIG. 6 is a side view illustrating the configuration of the printing unit and the cap unit. As shown in FIGS. 5 and 6, the print head H extends along two guide rails 31 extending in the main scanning direction X that coincides with the width direction of the paper P (the printer left-right direction) at the upper position of the paper P. It is configured to be movable. Further, the print head H has two head units 32 and 32 arranged in the sub-scanning direction Y that is perpendicular to the main scanning direction X and coincides with the moving direction of the paper P (the front-rear direction of the printer). By ejecting a plurality of colors of ink downward from a large number of ink ejection nozzles (not shown) provided on the lower surfaces of the two head units 32, 32, a predetermined image is formed on the printing surface of the paper P. It can be printed. In this embodiment, the head units 32 are arranged in two stages in the sub-scanning direction Y. However, the head units 32 do not have to be two stages, and may be one stage or three stages or more. Good.

  Both the head units 32 have the same configuration, and each has a plurality of nozzle arrays arranged in the main scanning direction X for ejecting ink of each color. In each nozzle array, ink discharge nozzles are arranged in a row in the sub-scanning direction Y. Thus, each head unit 32 is configured to be able to form a color image by itself. The paper P is transported intermittently (stepwise) in the sub-scanning direction Y by a constant unit transport amount by the supply roller 24 or the downstream roller pair 25, and at each stop of the paper P during the intermittent transport, The print head H is scanned once in the main scanning direction X (one-way operation or one-time operation), and at this time, ink is ejected from the ink discharge nozzles of each color of each head unit 32 at each position in the main scanning direction X. It discharges simultaneously with respect to the printing surface of P. That is, after one scan of the print head H, the paper P is transported by the unit transport amount, and then the print head H is scanned once again, and this operation is repeated to print a desired image.

  Here, as a configuration for ink discharge of the print head H in the present embodiment, ink is discharged from an ink discharge nozzle communicating with the pressure chamber by changing the volume of the pressure chamber filled with ink by a piezo element. The general piezo type is used.

  The platen 23 is made of a plate-like member, and its upper surface is a support surface 23 a that supports the paper P. The platen 23 is provided with a number of suction holes 23b penetrating in the thickness direction (vertical direction) and opening to the support surface 23a. A case body 35 (see FIG. 2) that forms a space with the platen 23 is disposed below the platen 23, and a suction device 36 (see FIG. 2) including a fan or the like is disposed below the case body 35. It is arranged. The suction hole 23b communicates with the space in the case body 35. This space communicates with the suction port of the suction device 36, and the operation of the suction device 36 causes the platen 23 to pass through the suction hole 23b. A negative pressure is generated on the support surface 23 a side, and the paper P is sucked and held on the support surface 23 a of the platen 23. Thereby, it becomes possible to ensure the flatness of the paper P at the time of printing and to improve the printing quality.

  On the support surface 23a of the platen 23, a recess 23c extending in the sub-scanning direction Y is formed. An ink absorbing material 38 is accommodated in the recess 23c. The ink absorbing member 38 is configured so that a part of the ink ejected from the print head H (head unit 32) in the width direction of the paper P on the support surface 23a when performing borderless printing for printing an image on the entire paper P. This is provided to prevent the support surface 23a of the platen 23 from being soiled by the ink that has come off the outer edge of the platen 23 even if it protrudes outward from the edge. For this reason, the concave portion 23c is located along the edge at the position corresponding to the edge in the width direction of the paper P on the support surface 23a and the position corresponding to the print head H in the sub-scanning direction Y on the support surface 23a. It is formed to extend (that is, to extend in the sub-scanning direction Y). In the example of FIG. 5, a total of 14 recesses 23c are provided.

  A flushing hole 23 d is formed at a position corresponding to the head units 32, 32 at the left end portion of the platen 23. The flushing hole 23d is for receiving a small amount of ink ejected from the nozzles of the print head H at the start of printing in order to prevent the ink from thickening.

  Further, a standby position for the print head H to wait when printing is not being performed is set at a position outside the print area in the main scanning direction X of the print head H. A portion 26 is provided. The cap portion 26 is in close contact with the head units 32 and 32 of the print head H in order to prevent the ink from being thickened when the print head H is not used. Two suction caps 26a arranged in the direction Y are provided. The cap unit 26 moves up and down between a position that is in close contact with the bottom surface of the print head H and a position that is away from the bottom surface of the print head H.

  On the rear side (right side in FIG. 5) of the print head H, there is provided a bearing holder 21a through which the rear guide rail 31 is inserted. That is, the print head H is rotatably supported with respect to the rear guide rail 31. On the other hand, on the front side (left side in FIG. 5) of the print head H, a head guide 21b protruding forward is provided. The head guide 21b is slidably mounted on the front guide rail 31 and supports the print head H so as to be horizontal together with the bearing holder 21a. As a result, when a paper jam occurs between the print head H and the platen 23, the front side of the print head H can be lifted and rotated about the rear guide rail 31 to improve maintainability. . Further, a clamping roller 27 is provided at a position above the front guide rail 31 at the standby position of the print head H.

  When the print head H moves to the standby position, the head guide 21b of the print head H is sandwiched between the clamping roller 27 and the front guide rail 31. Thereby, in the standby position, it is possible to prevent the print head H from being lifted when the cap portion 26 is lifted and closely contacts the bottom surface of the print head H. The cap portion 26 is configured to form a negative pressure space between the cap portion 26 and the bottom surface of the print head H, thereby sucking ink from the nozzles. The sucked ink is collected in a waste liquid tank (not shown).

  In the lower right part of the inkjet printer A, four ink cartridges (not shown) in which inks having different hues are enclosed are detachably accommodated. Accordingly, by attaching or detaching these ink cartridges, the used or used one can be replaced with a new one. Each of these ink cartridges contains yellow (Y), magenta (M), cyan (C), and black (K) inks.

  As shown in FIG. 2, on the rear side of the printer with respect to the downstream roller pair 25, when the paper P after printing is cut into a predetermined size or borderless printing is performed, the leading and trailing edges of the paper P are A cutter 50 for cutting the margin is provided.

  The cutter 50 is disposed on the lower side of the paper P conveyance path and the fixed blade 50a on the upper side of the paper P conveyance path, and is moved vertically with respect to the fixed blade 50a by a motor (not shown). The movable blade 50b is cut, and the movable blade 50b moves from the upper side to the lower side of the paper P to cut the paper P. Chips resulting from this cutting fall and are stored in a waste box (not shown) disposed in the lower portion of the housing 2.

  On the rear side of the printer with respect to the cutter 50, three pressure-conveying conveyance roller pairs 46 are provided that sandwich the paper P cut by the cutter 50 and further convey the paper P to the rear side of the printer.

  In the conveying roller pair 46, the lower driving roller 46a is driven by a motor (not shown), and the rotational speed thereof, that is, the conveying speed of the paper P by the conveying roller pair 46 is configured to be variable. Further, the driven roller 46b located on the upper side can switch between a state where it is pressed against the lower driving roller 46a and a state where the pressure is released.

  Specifically, the transport roller pair 46 is released from pressure contact before the leading end of the paper P cut by the cutter 50 is sandwiched between the rollers. In this way, it is possible to eliminate problems such as the leading end portion of the paper P being caught by the conveying roller pair 46 and being bent while the conveying roller pair 46 is crimped. Note that the pressure release of the driven roller 46b of the three conveying roller pairs 46 is simultaneously performed.

  The paper P transported by the transport roller pair 46 is transported to the switchback unit 72. The switchback unit 72 switches back the paper P and discharges the paper P from the rear end side of the paper P to the transport belt 101 so that the printing surface of the paper P faces the upper surface on the transport belt 101 of the conveyor device 100. is there.

  FIG. 7 is a schematic view showing a state in which the switchback roller pair of the switchback unit receives the paper transported from the transport roller pair, and FIG. 8 shows the driven roller of the switchback roller pair in the second position. FIG. 8 is a view corresponding to FIG. 7 showing a switched state.

  As shown in FIGS. 7 and 8, the switchback portion 72 includes a press-fit switchback roller pair 73 composed of a lower drive roller 73a and an upper driven roller 73b, and the switchback roller pair 73. A pair of first guide members 74 that are provided so as to sandwich the conveyance path on the upstream side and guide the paper P conveyed from the conveyance roller pair 46 to the switchback roller pair 73, and the backside printing described later on the switched back paper P A pair of pressure-feed type supply rollers 75 that are supplied to the apparatus 60, and a pair that is provided so as to sandwich the conveyance path between the switchback roller pair 73 and the supply roller pair 75, and guides the switched back paper P to the supply roller pair 75. The second guide member 76 is provided.

  The drive roller 73a of the switchback roller pair 73 has a normal rotation in which the paper P is nipped and conveyed to the front side of the printer by a motor (not shown), and a reverse rotation in which the paper P is nipped and conveyed to the rear side of the printer. It is configured to be possible.

  The switchback roller pair 73 and the first guide member 74 can be moved integrally around the rotation axis of the drive roller 73a of the switchback roller pair 73 by a motor (not shown). The relative position of the driven roller 73b with respect to the drive roller 73a of the roller pair 73 is located almost directly above the drive roller 73a as shown in FIG. 7, and the first position for conveying the paper P to the rear side of the printer. As shown in FIG. 8, the switch is switched to the second position which is located on the rear side of the printer with respect to the driving roller 73 a and supplies the switched back paper P from the rear end side to the back surface printing device 60. ing.

  Here, a switchback operation for switching back the paper P transported from the transport roller pair 46 will be described. When the switchback roller pair 73 receives the paper P transported from the transport roller pair 46, the drive roller 73a is rotating forward and the driven roller 73b is in the first position. Then, when the paper P is conveyed to the rear side of the printer by the switchback roller pair 73 by such an amount that the rear end of the paper P is positioned on the first guide member 74 (see FIG. 7), the forward rotation of the driving roller 73a is stopped. To do.

  At this time, the front end portion of the paper P is bent and bent downward due to its own weight. If the paper P is stiff and does not bend due to its own weight, the leading end of the paper P comes into contact with the curved guide plate 77 provided on the downstream side in the transport direction, so that the paper P moves downward along the curved guide plate 77. It can be bent.

  Subsequently, the switchback roller pair 73 and the first guide member 74 are rotated clockwise in FIG. 7 to switch the driven roller 73b from the first position to the second position. Thereby, the rear end side (front side of the printer) of the paper P is lifted.

  Thereafter, the drive roller 73a is rotated in the reverse direction, and the paper P is conveyed from the rear end side toward the supply roller pair 75 disposed on the upper side of the printer. The paper P to be switched back by the switchback roller pair 73 reaches the supply roller pair 75 through the first guide member 74 and the second guide member 76.

  In the present embodiment, the position of the switchback roller pair 73 is switched between the first position and the second position by moving the driven roller 73b around the drive roller 73a of the switchback roller pair 73. However, the present invention is not limited to this configuration. For example, the drive roller 73a and the driven roller 73b are both movable, and the first position and the first position can be changed by changing the position of the entire switchback roller pair 73. The position 2 may be switched.

  Further, in the present embodiment, the switchback roller pair 73 is configured by the driving roller 73a that transports the paper P and the driven roller 73b that rotates following the driving roller 73a. However, the driven roller 73b can be driven. Thus, both of the rollers constituting the switchback roller pair 73 may be configured by the drive roller 73a.

  As shown in FIG. 2, on the upstream side of the supply roller pair 75, a fourth sensor 43 (consisting of a light projecting part and a light receiving part) that detects the leading end of the paper P sent out from the switchback roller pair 73. It is arranged.

  The supply roller pair 75 includes a driving roller 75a driven by a motor (not shown) and a driven roller 75b pressed against the driving roller 75a. The pressure-bonded state of the driven roller 75b with respect to the drive roller 75a can be released.

  On the downstream side of the supply roller pair 75, a back surface printing device 60 for printing the serial number on the back surface of the paper P is provided. On the downstream side of the back surface printing device 60, four pressure-bonding downstream roller pairs 78 each including a driving roller 78a disposed on the left side of the conveyance path and a driven roller 78b positioned on the right side thereof are disposed. Yes. The drive roller 78a is driven by a motor (not shown).

  Next, the configuration of the back surface printing apparatus 60, which is a characteristic part of the present invention, will be described. FIG. 9 is a perspective view showing the configuration of the back surface printing apparatus. As shown in FIGS. 2 and 9, the back surface printing device 60 is configured by a dot impact type printing device, and includes an ink ribbon cassette 61 containing an ink ribbon 65, and a print head 62 that presses the ink ribbon 65. It has.

  The ink ribbon cassette 61 contains an ink ribbon 65 carrying ink. The ink ribbon 65 is housed by being folded in an ink ribbon cassette 61, and is sandwiched by a pair of ribbon transport rollers 63 provided in the ink ribbon cassette 61. An opening through which the ink ribbon 65 can pass is formed at the tip of the ink ribbon cassette 61. The ink ribbon 65 is formed in a loop shape, and a part of the ink ribbon 65 is exposed from the opening by being conveyed while being held between the ribbon conveyance roller pair 63.

  The print head 62 includes a plurality of needle pins 64, and the needle pins 64 are configured to reciprocate in the axial direction. The print head 62 presses a part of the ink ribbon 65 exposed from the opening with the needle pin 64. The ink ribbon 65 pressed by the needle pin 64 is pressed against the back surface of the paper P, and printing is performed by transferring the carried ink.

  By the way, in the back side printing device 60, since the print head 62 is disposed close to the transport path of the paper P, there is a possibility that the ink of the ink ribbon 65 adheres to the back side of the paper P during the paper transport and becomes dirty. is there. In particular, when printing is performed on both sides of the paper P, the ink of the ink ribbon 65 adheres to the printing surface of the paper P, which is not preferable because print quality deteriorates. Therefore, in the present invention, the print head 62 is retracted from the conveyance path when it is not necessary to perform the back surface printing as in the paper P for performing double-sided printing.

  FIG. 10 is a side view showing a state before the back surface printing apparatus is mounted in the housing, and FIG. 11 is a view corresponding to FIG. 10 showing a state where the back surface printing apparatus is positioned at the printing position.

  As shown in FIGS. 9 to 11, the back surface printing device 60 is arranged in two rows in the left-right direction of the printer and is accommodated in the main body 66. The main body 66 is detachable from the printing device housing 90 provided in the housing 2.

  The main body 66 is formed in a box shape in which the print head 62 side of the back surface printing device 60 is opened. A handle 66c is provided on the opposite side to the opening side of the main body 66 and on both sides of the printer in the left-right direction so that the operator can easily carry the main body 66.

  Cutout holes 66b are formed in the upper end portions of the main body side walls 66a standing on both the left and right sides of the main body portion 66 for engaging and supporting the support shaft 90b described later. By engaging and supporting the notch hole 66b with the support shaft 90b, the main body portion 66 is rotatable around the support shaft 90b. Further, lock pins 67 projecting outward are respectively provided at the lower left side of the main body side wall 66a on the left and right sides of the printer in FIG. 10, and positioning is performed at the center of the right side of the main body side wall 66a in FIG. Each of the pins 66d is provided.

  A cam shaft 68 is provided at the lower right side of the main body 66. The cam shaft 68 is supported at both ends rotatably across the main body side walls 66a on the left and right sides of the printer. Both left and right end portions of the cam shaft 68 pass through the main body side wall 66a, and drive cams 68a as position changing means are connected to the tip portions thereof.

  In FIG. 9, a drive motor 69 as a position changing means is provided inside the left main body side wall 66a. The drive motor 69 has a drive shaft that passes through the main body side wall 66a and protrudes outward from the main body 66, and a drive gear 69a is connected to the tip of the drive motor 69. The drive gear 69a is connected to a drive cam 68a disposed on the left side of FIG. 9 so that the drive motor 69 can be rotated to drive the drive cam 68a via the drive gear 69a. It has become.

  The printing apparatus housing portion 90 includes a housing side wall 90a disposed in the left-right direction of the printer. The accommodation side wall 90a is formed in an inverted L shape with its lower end extending to the left in FIG. A support shaft 90b extending in the width direction of the paper P (the printer left-right direction) is supported on both ends of the accommodation side wall 90a. A pin receiving portion 90c for receiving the positioning pin 66d of the main body 66 is formed at the corner portion of the accommodation side wall 90a having an inverted L shape.

  Cam followers 91 are respectively provided below the support shaft 90b and on the inner surface side of the housing side wall 90a. The cam follower 91 is configured to be crimped to or released from the driving cam 68 a by the rotational drive of the driving motor 69.

  Arm shafts 92 projecting outward are provided on the front side (left side in FIG. 10) of the cam follower 91 of the housing side wall 90a. A lock arm 93 is rotatably attached to the arm shaft 92.

  The lock arm 93 is formed in a rectangular parallelepiped shape having a spring accommodating chamber 93a therein. The spring accommodating chamber 93a accommodates a compression spring 94 and a spring pressing portion 93b that is slidable within the spring accommodating chamber 93a and presses the compression spring 94. The lock arm 93 is formed with a long hole 93c through which the arm shaft 92 is inserted.

  A spring pressing portion 93 b is connected to the distal end portion of the arm shaft 92. Accordingly, the lock arm 93 is urged by the urging force of the compression spring 94 so that the arm shaft 92 is positioned at the left end of the long hole 93c in FIG.

  A lock lever 95 is rotatably attached to the front end portion (left end portion in FIG. 10) of the lock arm 93 via a lever shaft 95a. The lock lever 95 is configured to sandwich the lock pin 67 with the lock arm 93 by rotating the lock lever 95 toward the lock pin 67 side of the main body 66 around the lever shaft 95a. Here, in the holding position of the lock pin 67 in the lock arm 93 and the lock lever 95, a recess 96 for fitting and holding the lock pin 67 is formed.

  When the lock pin 67 is pinched by the lock arm 93 and the lock lever 95, the lock arm 93 is urged so that the arm shaft 92 is positioned at the left end of the long hole 93c as shown in FIG. From the state, it moves to the left against the biasing force of the compression spring 94 and is biased so that the arm shaft 92 is positioned closer to the center of the long hole 93c. At this time, the positioning pin 66d provided on the main body side wall 66a of the main body 66 is received by the pin receiving portion 90c of the storage side wall 90a, and the main body 66 is positioned relative to the printing device storage 90. Thereby, the back surface printing apparatus 60 is positioned at a print position where printing can be performed on the back surface of the paper P with the print head 62 being brought close to the transport path of the paper P. Note that the cam surfaces of the drive cam 68a and the cam follower 91 are in a state where the pressure bonding is released.

  A supply roller pair 75 and a downstream roller pair 78 are disposed between the accommodating side walls 90 a of the printing apparatus accommodating portion 90. A pair of left and right guide plates 97 for guiding the paper P are provided between the supply roller pair 75 and the downstream roller pair 78. The print head 62 of the back surface printing apparatus 60 is exposed on the conveyance path through a hole formed in the left guide plate 97. Further, an opposing head 98 that prevents the paper P from being lifted during the pressing operation of the ink ribbon 65 by the print head 62 is disposed so as to face the print head 62, and through a hole formed in the right guide plate 97. It is exposed on the transport path.

  FIG. 12 is a view corresponding to FIG. 10 showing a state where the back surface printing apparatus is positioned at the retracted position. As shown in FIG. 12, in order to position the print head 62 of the back surface printing device 60 at the retracted position where the print head 62 is retracted from the paper P conveyance path, the drive motor 69 is driven to rotate and the cam surface of the drive cam 68a is placed on the cam follower 91. Press.

  At this time, the lock arm 93 moves to the left against the urging force of the compression spring 94 from the state where the arm shaft 92 is urged so as to be positioned closer to the center of the long hole 93c, and the long hole The arm shaft 92 is biased so as to be positioned at the right end of 93c. Further, the main body 66 rotates in the clockwise direction around the support shaft 90b.

  In this way, the print head 62 is moved from the print position close to the paper P transport path to the retreat position retracted from the paper P transport path simply by rotating the drive motor 69. It is possible to prevent the ink of the ink ribbon 65 from adhering to the printing surface of the paper P on which double-sided printing is performed.

  The changing operation for changing the position of the print head 62 between the print position and the retracted position is performed based on double-sided printing information indicating that the paper P for double-sided printing has been conveyed. The double-sided printing information may be input directly by the operator or automatically determined on the inkjet printer A side.

  Further, when the print head 62 is moved from the retracted position to the print position, it is preferable to carry out at the following timing. Specifically, among the papers P that are continuously transported on the transport path, when the preceding paper P is an order for double-sided printing and the subsequent paper P is an order for single-sided printing, the preceding paper P is the back surface printing device 60. After the detection by the fourth sensor 43, the print head 62 is moved based on the detection signal or the like until the subsequent paper P reaches the print start position of the print head 62 of the back surface printing device 60. What is necessary is just to make it move from a retracted position to a printing position.

  As the movement timing of the print head 62, the print start position on the paper P to be printed on the back surface (position set based on the length of the paper P, print information, etc.) reaches the print start position on the print head 62. In this case, the print head 62 may be moved from the retracted position to the print position. Thereby, it is possible to further reduce the risk of ink adhering to the printing surface and becoming dirty with respect to the paper P of the print order for printing on the back side. The movement timing of the print head 62 is controlled based on the detection signal of the fourth sensor 43.

  In the present embodiment, the position of the print head 62 is changed between the print position and the retracted position based on the double-sided printing information. However, the necessity of backside printing is set for each print order. May be.

  Specifically, when performing backside printing, it is set as “requires backside printing” by an operator's input or the like, and when the double-sided printing information is acquired as described above, the print head 62 is moved from the printing position. When the double-sided printing information is not acquired while moving to the retracted position, the print head 62 is positioned at the printing position. Further, when the back side printing is not performed, “back side printing is rejected” is set, and the print head 62 is turned on while the printing process of the order is performed regardless of the order of the single side printing or the order of the double side printing. Position it in the retracted position.

  As shown in FIG. 2, on the right side of the conveyance path of the downstream roller pair 78, drying air for drying the ink attached to the printing surface of the paper P in the printing unit 21 is blown onto the printing surface of the paper P. A drying device 56 is provided. The drying device 56 includes a suction fan 57 for taking air into the drying device 56, a heater 58 for heating the air taken in by the suction fan 57, and an opening on the front side of the drying device 56. Exhaust nozzle portions 59 that blow the air heated in step 1 on the printing surface of the paper P as dry air are provided in two rows, upper and lower, respectively.

  Here, since the degree of ink drying by the drying device 56 changes according to the environmental conditions (temperature, humidity, etc.) in which the ink jet printer A is installed, the rotation speed of the downstream roller pair 78 is changed, and the paper The conveyance speed of P is changed. The paper P dried by the drying device 56 is conveyed to the discharge roller pair 80. A fifth sensor 44 (consisting of a light projecting part and a light receiving part) that detects the leading edge of the paper P fed from the downstream roller pair 78 is disposed on the downstream side of the drying device 56.

  The discharge roller pair 80 discharges the printed paper P onto the conveyor belt 101 of the conveyor device 100 through the discharge port 85. Here, the paper P wound in a roll shape in the magazine M is curled with a curl and needs to be decurled. Therefore, the discharge roller pair 80 can perform a decurling process for correcting the curl of the paper P. Specifically, the discharge roller pair 80 includes a conveyance roller 81 that conveys the paper P to the conveyor device 100, and a decurling roller 82 that sandwiches the paper P together with the conveyance roller 81. In addition, a free roller 83 that rotates in conjunction with the movement of the paper P to be transported is disposed on the upstream side of the transport roller 81.

  Here, by changing the relative position of the decurling roller 82 with respect to the conveying roller 81, it is possible to switch between a conveying position for conveying the paper P without decurling and a decurling position for conveying the paper P while decurling. In this way, the paper P decurled by the decurling roller 82 is discharged onto the transport belt 101 of the conveyor device 100 through the discharge port 85.

  As shown in FIG. 1, the conveyor device 100 is for placing the paper P discharged from the discharge port 85 of the housing 2, and a conveyor belt 101 that conveys the placed paper P in a belt conveyor manner. A driving roller 102 for driving the conveying belt 101, a conveying main body 103 that rotatably supports the driving roller 102, and an upstream side in the conveying direction of the conveying belt 101 attached to the conveying main body 103 (left side in FIG. 1). And a large-format tray 104 disposed in

  A position corresponding to the discharge port 85 of the housing 2 in the transport belt 101 is a placement area for receiving the paper P immediately after being discharged through the discharge port 85. Then, the conveyor device 100 removes the paper P already placed from the placement area before the paper P to be discharged next through the discharge port 85 of the housing 2 is placed in the placement area. The conveyance belt 101 is driven and controlled to be retracted.

  Thereby, since the paper P does not overlap on the said conveyance belt 101, the color nonuniformity etc. of the print image which arise when the ink on paper P does not dry uniformly can be suppressed.

  In addition, when the next paper P is transported, the paper P that has already been placed is not intermittently fed to the outside of the placement area at once, but the transport belt 101 is continuously driven at a constant speed. Also good.

  Here, when the photographic size paper P such as an L plate is placed on the conveyor belt 101, the conveyor device 100 is arranged on the downstream side (right side in FIG. 1) in the conveying direction. On the other hand, when large paper P such as B5 size or A4 size is placed, the drive control is performed so that the paper is transported to the large tray 104 on the upstream side in the transport direction. As described above, if the transport direction is switched according to the size of the paper P, the paper P can be transported to an appropriate storage position for each paper size.

  The stacking device 110 is disposed on the downstream side in the transport direction of the conveyor device 100, and is used to stack the paper P transported from the conveyor device 100. A box-shaped stacking main body 111 having an open front side; An endless stacking belt 113 wound around a pair of rollers (not shown) disposed at both upper and lower ends in the stacking main body 111 with appropriate tension, and an outer circumferential surface of the stacking belt 113 at substantially equal intervals. And an integrated plate 112 provided on the substrate. The roller pair is connected to a drive motor (not shown) for rotating the accumulation belt 113 to move the accumulation plate 112 in the transport direction.

  Of the plurality of stacking plates 112, the stacking plate 112 exposed to the outside of the stacking main body 111 moves downward following the rotation of the stacking belt 113, and is accommodated in the stacking main body 111. The accumulation plate 112 is configured to move upward following the rotation operation of the accumulation belt 113. That is, the accumulation plate 112 is configured to be able to rotate continuously around the roller pair together with the accumulation belt 113.

  The stacking plate 112 waits at the delivery position of the paper P on the downstream side of the conveying belt 101 so that the plate surface is horizontal and substantially flush with the belt surface of the conveying belt 101, and the predetermined printing order is satisfied. After the corresponding number of sheets are stacked, the paper P of the next order is transported downward by the stacking belt 113 before being transported.

  Specifically, first, the paper P is stacked on the stacking plate 112 positioned at the stacking standby position (the position at which the stacking plate 112 is waiting horizontally to stack the paper P). For example, one order of paper P is stacked on the stacking plate 112.

  Next, the accumulation belt 113 is driven to move the accumulation plate 112 downward by one. That is, when the stacking plate 112 on which the paper P for one order is stacked moves downward, the new stacking plate 112 is positioned at the stacking standby position.

  Then, by repeating such stacking and transporting for each order, it becomes possible to stack and transport the paper P for each order between the adjacent stacking plates 112. Then, before each stacking plate 112 is filled with the paper P, an operator takes out and collects the paper P stacked on each stacking plate 112.

  In addition, a guide plate 115 standing in the vertical direction is provided at the paper P transfer position of the stacking main body 111. The guide plate 115 is for guiding the paper P delivered from the conveyor device 100 to the stacking device 110 side so as to be stacked on the stacking plate 112 with the right edge aligned.

  The stacking device 110 accommodates photographic paper P such as L-size, while the large tray 104 accommodates large paper P such as B5 size and A4 size. However, for example, when printing is performed on a long paper P exceeding the paper size that can be placed on the large tray 104, the length of the paper P is larger than the width of the transport belt 101 of the conveyor device 100. Since it is large, the paper P passes through the transport belt 101 in the width direction and falls from the top of the housing 2.

  Therefore, in the inkjet printer A according to the present embodiment, the discharge tray 87 is provided so as to stand upright on the opposite side of the discharge port 85 of the housing 2 with the conveyance belt 101 interposed therebetween. Further, the operator collects the paper P after single-sided printing placed on the discharge tray 87, inserts it into the manual feed tray 7 with the image-printed side facing down, and performs the printing process again. Printing on both sides is possible.

  As described above, the present invention is extremely useful because it provides a highly practical effect of preventing ink ribbon ink from adhering to the printing surface of paper for duplex printing. Industrial applicability is high.

60 Back side printing device (Back side printing means)
62 Print Head 65 Ink Ribbon 66 Main Body 68 Drive Motor (Position Changing Unit)
68a Driving cam (position changing means)
90b Support shaft 91 Cam follower A Inkjet printer (image forming apparatus)
P paper

Claims (3)

An image forming apparatus provided with a back surface printing means for transferring ink by pressing an ink ribbon carrying ink against the back surface of a paper printing surface,
The back surface printing means includes
A print head for pressing the ink ribbon;
Position change means for changing the position of the print head to a print position that can be printed on the back surface of the paper in the vicinity of the paper conveyance path and a retreat position that is retreated from the paper conveyance path. An image forming apparatus. In claim 1,
The position changing unit is configured to change the position of the print head from the printing position to the retracted position based on double-sided printing information indicating that double-sided printing is performed on the paper. Image forming apparatus. In claim 1 or 2,
A support shaft extending in the width direction of the paper;
A cam follower disposed below the support shaft;
A main body that accommodates the print head and is rotatably supported with respect to the support shaft;
The position changing means includes a drive cam provided in the main body so as to correspond to the cam follower, and a drive motor that rotationally drives the drive cam, and the drive cam is rotated by the drive motor. An image forming apparatus configured to change the position of the print head from the print position to the retracted position by pressing the cam follower and rotating the main body about the support shaft. .

Images