JP2015093418A - Line printer and movement method for print head of line printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer, whose printer head is prevented from colliding a paper floating-up preventing member or the like provided on a platen when the print head is moved in a direction orthogonal to a direction in which the print head opposes to the platen to be arranged at a position where the print head opposes to the platen.SOLUTION: A carriage 11 of a line printer 1 comprises a head unit 12 for holding a print head 8 and a carriage frame 13 that supports the head unit 12 to be movable vertically. When the carriage 11 is moved from a stand-by position 11B and then arranged at an opposite position 11a, the head unit 12 is moved while being arranged at a unit elevated position 12A where a gap between a platen unit 17 and the head unit has a first distance L1. Thereafter, in the stand-by position 11B, the head unit 12 is made to descend from the unit elevated position 12A to a unit descended position 12B where a platen gap G has a second distance shorter than the first distance L1.

Description

  The present invention relates to a line printer in which a print head moves between a position facing a platen and a position deviated laterally from a position facing the platen, and a print head moving method of the line printer.

  A line printer that prints on a recording sheet conveyed on a platen at a constant speed is described in Patent Document 1. The line printer of Patent Document 1 includes an inkjet head as a print head. The print head is composed of four sets of line-type ink jet heads that discharge ink droplets of cyan, black, magenta, and yellow, and each line-type ink jet head has a width that exceeds the width of the recording paper. Further, they are arranged at regular intervals along the conveying direction of four sets of line-type ink jet head recording paper. Accordingly, the print head is increased in size in the width direction and the conveyance direction of the recording paper.

JP 2011-025479 A

  When an inkjet head is mounted as a print head, it is desired to perform capping to cover the ink nozzle surface of the print head with a head cap when the printer is in a standby state. This is because the capping can reduce the evaporation of ink moisture from the ink nozzle surface and suppress the ink thickening. In addition, it is desired to perform a flushing operation for ejecting ink droplets from the print head to the head cap every time a certain period of time elapses. This is because the clogging of the ink nozzles can be prevented or eliminated by the flushing operation.

  When performing capping and flushing operations of a print head in a line printer, a head standby position in which a head cap is arranged on the side of the platen is provided like a serial printer, and the print head is opposed to the platen and the head. It is conceivable to move in the horizontal direction between the standby positions. However, there is a case where the print head of the line printer is enlarged as in Patent Document 1. In this case, since the range of the recording paper facing the print head on the platen becomes wide, if the print head is retracted from the position facing the platen, the recording paper tends to float, and then the print head faces the platen. When returning to the position, the print head and the recording paper collide with each other, and the print head is easily damaged or jammed.

  Here, in order to prevent the recording paper from being lifted up, it is conceivable to provide a floating prevention member such as a star wheel that comes into contact with the recording paper transported from the platen from above. However, when such a lift prevention member is provided, there is a problem that the lift prevention member and the print head collide when the print head is moved in the horizontal direction from the head standby position to a position facing the platen.

  In view of the above, the problem of the present invention is to move the print head disposed at the head standby position away from the position facing the platen in a direction perpendicular to the facing direction of the print head and the platen. And a method of moving the print head of the line printer in which the print head does not collide with a member such as a paper lifting prevention member provided on the platen.

  In order to solve the above problems, a line printer according to the present invention includes a print head, a platen, a head unit that holds the print head, and a gap between the print head and the platen is a first distance. A carriage including a frame that movably supports the head unit between a first position and a second position where the gap is a second distance shorter than the first distance, and the print head and the platen. A carriage moving mechanism for moving the carriage between a facing position facing each other and a standby position where the print head and the platen are not facing each other, and when the carriage is placed at the facing position, the carriage is disposed at the first position. A head unit moving mechanism for moving the head unit being moved to the second position.

  According to the present invention, the head unit that holds the print head is supported on the frame so as to be movable between the first position and the second position. Therefore, when the print head that is not opposed to the platen is moved to the position opposed to the platen, the head unit is disposed at the first position, and the gap between the print head and the platen is the first that has a long distance. It can be a distance. Thereby, for example, even when a paper floating prevention member for preventing the recording paper from floating is arranged on the platen, it is possible to prevent these members from colliding with the print head. In addition, after the carriage is disposed at the opposed position and the print head is moved to the position opposed to the platen, the head unit is moved from the first position to the second position on the frame so that the gap between the print head and the platen is increased. Can be shortened. Therefore, this gap can be set to a distance suitable for printing, for example.

  In the present invention, it is desirable that the head unit moving mechanism moves the carriage in a direction perpendicular to the facing direction of the print head and the platen in order to accurately place the print head at the facing position.

  In the present invention, the carriage includes a biasing member that biases the head unit to the first position, and the head unit moving mechanism moves the head unit against the biasing force of the biasing member. It is desirable to move from one position to the second position. This makes it easy to move the carriage from the standby position to the facing position with the head unit disposed at the first position. Further, when the head unit is moved to the second position, the urging force of the urging member is applied to the head unit, so that the head unit moved to the second position can be easily returned to the first position.

  In the present invention, the second position is preferably a position where printing can be performed on the recording paper on the platen by the print head. If it does in this way, printing can be performed by the print head arranged in the 2nd position.

  In this case, when the print head is disposed at the second position, in order to set the gap between the print head and the platen to a desired distance, the gap between the print head and the platen is constant. Preferably, the gap forming member abuts both the carriage and the platen when the head unit is disposed at the second position. It is desirable to have a gap forming member that abuts both the carriage and the platen when the head unit is disposed at the second position and makes the gap between the print head and the platen constant.

  In this case, in order to maintain a gap between the print head and the platen at a desired distance when the print head is disposed at the second position, at least one of the head unit and the platen includes: It is preferable that a gap forming protrusion is provided that abuts the other when the head unit is disposed at the second position and makes a gap between the print head and the platen constant.

  In the present invention, in order to make the movement of the head unit moving from the first position to the second position smooth, the carriage includes a guide mechanism for guiding the movement of the head unit, and the guide mechanism It is desirable to include a guide groove provided in one of the head unit and the frame, and a guide roller provided in the other and inserted into the guide groove.

  In this case, the guide groove extends in the facing direction of the print head and the platen, and the first groove width is substantially the same as the width dimension of the guide roller in order from the side closer to the platen. A first groove portion having a dimension and a second groove portion having a second groove width dimension that is longer than the first groove width dimension, and in this order from the side closer to the carriage in the facing direction as the guide roller. The first guide roller and the second guide roller arranged in the above, and when the head unit moves between the first position and the second position, the first guide roller has the first groove portion. It is preferable that the second guide roller moves and the second groove portion moves. In this way, the second guide roller can move the second groove portion in a direction intersecting the extending direction (opposing direction) of the guide groove, so that the head unit can change its posture on the frame. it can. Therefore, when the head unit is disposed at the second position, if the ink nozzle surface of the print head and the platen surface (the surface facing the print head in the platen) are not parallel, the unit head and the gap The head unit is mounted on the frame by contact of the forming protrusion, contact of the gap forming protrusion provided on the head unit and the platen, or contact of the gap forming protrusion provided on the platen and the head unit. The ink nozzle surface and the platen surface of the print head can be made parallel by inclining. Thereby, the gap between the print head and the platen can be made constant.

  Next, in the method for moving the print head of the line printer according to the present invention, the print head at the head standby position not facing the platen is moved in a state where the gap between the platen and the print head is maintained at the first distance. The print head is disposed at a head facing position facing the platen, and the print head is moved in a direction approaching the platen at the head facing position so that the gap between the print head and the platen is greater than the first distance. Is a short second distance.

  According to the present invention, when the print head at the head standby position is moved to the head facing position, the gap between the print head and the platen is maintained at the first distance having a long distance. Therefore, for example, even when a paper floating prevention member for preventing the recording paper from floating is arranged on the platen, it is possible to prevent these and the print head from colliding with each other. Further, after the print head moves to the head facing position, the print head is moved closer to the platen side, and the gap between them is shortened to the second distance. Therefore, if the second distance is set to a distance suitable for printing, printing by the print head can be started thereafter.

  According to the present invention, when the print head in the head standby position is moved to a position facing the platen, the gap between the print head and the platen is set to the first distance having a long distance, and the print head faces the platen. After being placed in position, this gap can be the second short distance. Therefore, when the print head is moved from a position that does not face the platen to a position that faces the platen, there is no collision with a paper floating prevention member that prevents the recording paper from floating on the platen. In addition, the gap between the print head and the platen can be made appropriate at the position where the print head and the platen face each other.

1 is an external perspective view of a line printer according to an embodiment of the present invention. It is a schematic longitudinal cross-sectional view which shows the internal mechanism of the line printer of FIG. It is explanatory drawing which shows a paper conveyance mechanism typically. It is a perspective view of the carriage which mounts a print head. FIG. 6 is a bottom view when a carriage on which a print head is mounted is viewed from below. It is a perspective view of a head unit holding a print head. It is a perspective view of a carriage frame. It is a perspective view of a head unit moving mechanism. It is explanatory drawing of the head unit raising / lowering operation | movement by a head unit moving mechanism. It is a perspective view of a platen unit. It is a perspective view of a gap formation unit and a platen unit. It is explanatory drawing of a gap formation unit. FIG. 10 is an explanatory diagram of a movement operation of a print head and a carriage. It is explanatory drawing of the state by which the head unit is arrange | positioned in the 1st position. It is explanatory drawing of the state by which the head unit is arrange | positioned in the 2nd position.

  Hereinafter, an embodiment of a line printer to which the present invention is applied will be described with reference to the drawings.

(overall structure)
FIG. 1 is an external perspective view of a line printer according to an embodiment of the present invention. FIG. 2 is a schematic longitudinal sectional view showing the internal mechanism. As shown in FIG. 1, the line printer 1 includes a printer housing 2 having a rectangular parallelepiped shape that is long in the front-rear direction as a whole. In the upper part of the front surface 2a of the printer housing 2, an operation panel 3 is provided on one side in the width direction, and a paper discharge port 4 is formed on the other side. A maintenance opening / closing lid 5 is provided below the paper discharge port 4. In the following description, three directions orthogonal to each other are defined as a printer width direction X, a printer front-rear direction Y, and a printer vertical direction Z.

  As shown in FIG. 2, a roll paper storage unit 7 for loading the roll paper 6 is formed in the lower part of the rear side inside the printer housing 2. In addition, a paper conveyance path 9 is formed in the printer casing 2 from the roll paper storage unit 7 to the paper discharge port 4 via the print position A by the print head 8. The paper conveyance path 9 includes a first paper conveyance path portion 9a extending obliquely upward from the roll paper storage unit 7 toward the printer rear Y2 (backward in the front-rear direction of the printer), and the front end of the printer from the upper end of the first paper conveyance path portion 9a. A second paper conveyance path portion 9b that curves in Y1 (front in the front-rear direction of the printer), a third paper conveyance path portion 9c that gently descends from the front end of the second paper conveyance path portion 9b toward the printer front Y1, A fourth paper transport path portion 9d extending horizontally from the front end of the three paper transport path portion 9c to the printer front Y1 is provided.

  The print head 8 is disposed in the upper part on the front end side of the printer housing 2. The print head 8 is an inkjet head and is mounted on the carriage 11 with its ink nozzle surface 8a facing downward. The carriage 11 includes a head unit 12 that holds the print head 8 and a carriage frame (frame) 13 that supports the head unit 12 in a state of moving in the printer vertical direction Z. The print head 8 and the carriage 11 are disposed above the fourth paper transport path portion 9d. The print position A is provided in the middle of the fourth paper conveyance path portion 9 d and is defined by a platen unit (platen) 17 disposed below the print head 8.

  A pair of carriage guide shafts 14 extending in the printer width direction X are arranged in parallel on both sides of the carriage 11 in the front-rear direction Y of the printer. The carriage 11 is supported by the pair of carriage guide shafts 14 so as to be movable in the printer width direction X. A carriage moving mechanism 15 is disposed behind the printer Y2 of the print head 8, and the carriage 11 is moved along the pair of carriage guide shafts 14 by the carriage moving mechanism 15.

  Here, the carriage 11 moves between an opposing position 11A indicated by a dotted line in FIG. 1 and a standby position 11B indicated by a two-dot chain line in FIG. At the facing position 11A, the print head 8 mounted on the carriage 11 and the platen unit 17 face each other. That is, in the state where the carriage 11 is disposed at the facing position 11A, the print head 8 is located at the head facing position 8A facing the platen unit 17, as shown in FIG. On the other hand, at the standby position 11B, the print head 8 mounted on the carriage 11 and the platen unit 17 do not face each other. That is, in a state where the carriage 11 is disposed at the standby position 11B, the print head 8 is positioned at the head standby position 8B that is separated from the head facing position 8A in the first direction X1 (direction toward one side in the printer width direction). ing. A head maintenance unit 18 is disposed below the head standby position 8B. When the print head 8 is disposed at the head standby position 8B, the print head 8 faces the head maintenance unit 18. The head maintenance unit 18 includes a head cap that can cover the ink nozzle surface 8a of the print head 8 disposed at the head standby position 8B. A head unit moving mechanism 19 that lowers the head unit 12 when the carriage 11 is disposed at the facing position 11A is disposed above the carriage 11.

  The platen unit 17 includes a horizontal platen surface 17 a that faces the ink nozzle surface 8 a of the print head 8. The platen surface 17a defines a fourth paper transport path portion 9d. The platen surface 17a is constituted by a horizontal belt portion 21a of the conveyance belt 21 described later.

  A gap forming unit 22 is disposed between the head unit 12 and the platen unit 17. The gap forming unit 22 is in contact with both the head unit 12 and the platen unit 17 and has three spheres (gap forming) that make the platen gap G between the print head 8 and the platen unit 17 constant at a preset set distance. Members) 23 to 25 (see FIG. 12).

  A paper supply roller 31 is disposed at the bottom of the roll paper storage unit 7. The paper supply roller 31 is always held in contact with the roll paper 6 mounted in the roll paper storage unit 7 from below. The paper supply roller 31 is driven by a supply motor (not shown). When the paper supply roller 31 is driven, the long recording paper 6a is fed out from the roll paper 6 toward the first paper conveyance path portion 9a.

  A tension lever 32 that applies a back tension to the recording paper 6a conveyed along the paper conveyance path 9 is disposed in the second paper conveyance path portion 9b. The tension lever 32 defines the second paper transport path portion 9b and has an arcuate outer peripheral surface that protrudes toward the printer rear Y2. The tension lever 32 is attached at its lower end portion so as to be rotatable about a rotation center axis 32a extending in the printer width direction X, and is urged toward the printer rear Y2 by a spring member (not shown). .

  A paper guide 33 is disposed in front of the tension lever 32 on the printer Y1. The paper guide 33 defines the third paper conveyance path portion 9c, and has a shape that gently descends toward the front Y1 of the printer.

  Here, a belt-type paper transport mechanism 35 is mounted on the platen unit 17. FIG. 3 is an explanatory diagram schematically showing the paper transport mechanism 35. The paper transport mechanism 35 includes a transport belt 21 that is an endless belt disposed below the fourth paper transport path portion 9d, a plurality of guide rollers 36a to 36e around which the transport belt 21 is bridged, and a transport belt 21. Belt driving roller 36f for driving the belt and a transport motor 38 for rotating the belt driving roller 36f. The conveyor belt 21 is pressed against the belt driving roller 36f by a guide roller 36a. By rotating the belt drive roller 36f, the transport belt 21 moves along a route passing through the guide rollers 36a to 36e.

  In the conveyance belt 21, a portion stretched between the guide rollers 36 c and 36 d is a horizontal belt portion 21 a that extends horizontally along the fourth paper conveyance path portion 9 d. Pinch rollers 37a and 37b are pressed from above the platen unit 17 to the upstream end and the downstream end in the transport direction (printer longitudinal direction Y) in the horizontal belt portion 21a. The paper transport mechanism 35 transports the recording paper 6a sandwiched between the pinch rollers 37a and 37b and the horizontal belt portion 21a.

  As shown in FIG. 2, the recording paper 6 a is drawn from the roll paper 6 loaded in the roll paper storage unit 7 along the first paper conveyance path portion 9 a of the paper conveyance path 9. Then, the recording paper 6a is stretched over the tension lever 32 to bend along the second paper conveyance path portion 9b, and the leading end side portions thereof are the third paper conveyance path portion 9c and the fourth paper conveyance path portion 9d. It is set in the state extended along. Thereafter, a feeding operation by the paper feeding roller 31 is performed, and further, a feeding operation by the paper feeding mechanism 35 is performed, and a cueing operation for placing the top of the recording paper 6 a at the printing position A by the printing head 8 is performed. Thereafter, the paper transport mechanism 35 performs a transport operation of continuously transporting the paper from the printing position A toward the paper discharge port 4 at a constant speed in the forward feed direction. In synchronism with this transport operation, the print head 8 is driven and controlled to print on the surface of the recording paper 6a transported at the print position A.

(Print head and carriage)
FIG. 4 is a perspective view of the carriage 11 on which the print head 8 is mounted. FIG. 5 is a bottom view of the print head 8 and the carriage 11 as viewed from the platen unit 17 side. FIGS. 6A and 6B are perspective views of the head unit 12 that holds the print head 8 as viewed from one side and the other side in the printer width direction X. FIG. FIG. 7 is a perspective view of the carriage frame 13 that supports the head unit 12 as viewed from one side in the printer width direction X. FIG.

  As shown in FIGS. 5 and 6, the print head 8 includes four sets of line-type inkjet heads 41 to 44. Each of the line-type ink jet heads 41 to 44 has a width that exceeds the width of the recording paper 6a that can be transported through the paper transport path 9, and has a rectangular parallelepiped shape that is long in the printer width direction X as a whole. The four sets of line-type ink jet heads 41 to 44 eject black ink, cyan ink, magenta ink, and yellow ink, respectively.

  As shown in FIG. 6, the head unit 12 includes a bottom plate portion 45 having a rectangular outline, a square tube portion 46 that rises upward from the outer peripheral edge of the bottom plate portion 45, and an upper end of the square tube portion 46 from the center portion of the bottom plate portion 45. And an operating portion 50 protruding upward.

  As shown in FIG. 5, the bottom plate portion 45 has four rectangular openings 45 a to 45 d that are long in the printer width direction X. The openings 45a to 45d are provided at regular intervals in the longitudinal direction Y of the printer. Each of the line-type ink jet heads 41 to 44 is inserted into the rectangular tube portion 46 from above, and is held by the head unit 12 with its lower portion protruding downward from each of the openings 45a to 45d. Thus, the four sets of line type ink jet heads 41 to 44 are arranged at regular intervals along the front-rear direction Y of the printer.

  Further, as shown in FIG. 5, the bottom plate portion 45 is provided with first to third carriage side contact portions 47 to 49 that can contact the three spheres 23 to 25 of the gap forming unit 22, respectively. . The first carriage side abutting portion 47 is provided on a protruding portion 45e that protrudes forward from the front edge of the end portion of the bottom plate portion 45 in the second direction X2 (the direction toward the other side in the printer width direction). The second carriage side abutting portion 48 is provided on a protruding portion 45f protruding rearward from the rear end edge of the end portion of the bottom plate portion 45 in the second direction X2. The third carriage side contact portions 47 to 49 are provided at the edge portion 45g in the first direction X1 in the center portion of the bottom plate portion 45 in the front-rear direction Y of the printer. The position where the first carriage side contact portion 47 and the second carriage side contact portion 48 are provided is a position that is out of the print head 8 in the second direction X2, and is located on the third carriage side. The positions where the contact portions 47 to 49 are provided are positions that are out of the print head 8 in the first direction X1.

  As shown in FIG. 6, each carriage-side contact portion 47 to 49 is a columnar protrusion that protrudes downward. The lower end surfaces of the carriage-side contact portions 47 to 49 are flat surfaces, and are located above the ink nozzle surface 8a of the print head 8 in the up-down direction Z of the printer, as shown in FIG. Here, an imaginary plane defined by the lower end surfaces 47 a, 48 a, and 49 a of the three carriage side contact portions 47 to 49 is a plane parallel to the ink nozzle surface 8 a of the print head 8 and is set in the head unit 12. Reference plane 12a (see FIGS. 15 and 16).

  As shown in FIG. 6, the rectangular tube portion 46 has a first side wall portion 51 extending in the printer front-rear direction Y outside the second direction X2 of the print head 8 and the print head 8 sandwiched between the printer width direction X. A second sidewall portion 52 that faces the first sidewall portion 51; a third sidewall portion 53 that extends in the printer width direction X and that is continuous with the first sidewall portion 51 and the front end portion of the second sidewall portion 52; A fourth side wall portion 54 extending in the direction X and continuing the rear end portion of the first side wall portion 51 and the second side wall portion 52 is provided. Three reinforcing plates 55 a to 55 c that connect the first side wall portion 51 and the second side wall portion 52 are arranged between the line type ink jet heads 41 to 44 arranged in the longitudinal direction Y of the printer in the rectangular tube portion 46. Is provided. Of the three reinforcing plates 55a to 55c, the operating portion 50 is integrally formed on the reinforcing plate 55b located in the center in the printer longitudinal direction Y. A contact portion 50 a with which the operation lever 77 (see FIG. 8) of the head unit moving mechanism 19 abuts is provided at the upper end portion of the operation portion 50.

  As shown in FIG. 6A, the first side wall portion 51 includes a first lower guide roller (first guide roller) 60 and a first upper guide roller (second guide) in the center portion in the printer front-rear direction Y. Roller) 61 is attached. The first lower guide roller 60 and the first upper guide roller 61 are arranged apart from each other in the up-down direction Z of the printer with their respective rotation axes directed in the printer width direction X. The first lower guide roller 60 is located below the first upper guide roller 61.

  As shown in FIG. 6B, a second guide roller 62 is attached to the second side wall portion 52 at the center portion in the front-rear direction Y of the printer. The second guide roller 62 is disposed coaxially with the first lower guide roller 60 with the rotation axis directed in the printer width direction X.

  A third lower guide roller (first guide roller) 63 and a third upper guide roller (second guide roller) 64 are attached to the third side wall portion 53 at the central portion in the printer width direction X. The third lower guide roller 63 and the third upper guide roller 64 are arranged apart from each other in the up-down direction Z of the printer with their respective rotation axes directed in the front-rear direction Y of the printer. The third lower guide roller 63 is located below the third upper guide roller 64. The third lower guide roller 63 is disposed between the first lower guide roller 60 and the first upper guide roller 61 in the printer vertical direction Z. The third upper guide roller 64 is disposed above the first upper guide roller 61 in the printer vertical direction Z. Each guide roller 61-65 is the same thing provided with the same diameter, respectively.

  As shown in FIG. 7, the carriage frame 13 has a frame shape and supports the head unit 12 on the inner peripheral side thereof. The carriage frame 13 includes a first carriage frame portion 65 positioned outside the first side wall portion 51 of the head unit 12 in the second direction X2, and a second carriage frame portion positioned outside the second side wall portion 52 in the first direction X1. 66, a third carriage frame portion 67 located in the printer front Y1 of the third side wall portion 53, and a fourth carriage frame portion 68 located in the printer rear Y2 of the fourth side wall portion 54.

  As shown in FIG. 7A, the first carriage frame portion 65 is formed with a first guide groove 69 extending in the up-down direction Z of the printer. The first guide groove 69 has a first groove portion 69a having a first groove width dimension substantially the same as the width dimension of the second guide roller 62 in order from the bottom to the top, and is longer than the first groove width dimension. A second groove portion 69b having a second groove width dimension is provided. A second guide groove 70 extending in the printer vertical direction Z is formed in the second carriage frame portion 66. As shown in FIG. 7B, the second guide groove 70 has the same groove shape as the first guide groove 69. That is, the second guide groove 70 is, in order from the lower side, a first groove portion 70a having a first groove width dimension substantially the same as the width dimension of the second guide roller 62, and is longer than the first groove width dimension. A second groove portion 70b having a second groove width dimension is provided.

  The third carriage frame portion 67 is provided with a front support portion 71 that is supported by the carriage guide shaft 14 located in the front Y1 of the printer among the pair of carriage guide shafts 14. The third carriage frame portion 67 is provided with a protruding portion 72 that protrudes upward from the front support portion 71. A third guide groove 73 extending in the up-down direction Z of the printer is formed on the rear end surface of the protrusion 72. The third guide groove 73 has a first groove portion 73a having a first groove width dimension substantially the same as the width dimension of the second guide roller 62 in order from the lower side to the upper side, and the first groove width dimension. A second groove portion 73b having a long second groove width dimension is provided (see FIGS. 14 and 15).

  The fourth carriage frame portion 68 is provided with a rear support portion 74 that is supported by the carriage guide shaft 14 positioned at the rear Y2 of the printer among the pair of carriage guide shafts 14.

  When the head unit 12 is disposed inside the carriage frame 13, the first lower guide roller 60 and the first upper guide roller 61 are inserted into the first guide groove 69, as shown in FIG. The two guide rollers 62 are inserted into the second guide groove 70. Further, the third lower guide roller 63 and the third upper guide roller 64 are inserted into the third guide groove 73. Accordingly, the head unit 12 includes a unit rising position (first position) 12 </ b> A where the first upper guide roller 61 is located at the upper end portion of the first guide groove 69, and the first lower guide roller 60 is the first guide groove 69. Is supported by the carriage frame 13 so as to be movable between a unit lowering position (second position) 12B positioned at the lower end portion of the carriage. Further, four coil springs (biasing members) 75 are bridged between the head unit 12 and the carriage frame 13. The head unit 12 is biased to the unit raised position 12 </ b> A by the biasing force of the four coil springs 75.

  Here, the carriage moving mechanism 15 for moving the carriage 11 in the printer width direction X between the facing position 11A and the standby position 11B is the same as the mechanism for moving the print head in the serial printer. The carriage moving mechanism 15 includes, for example, a pair of timing pulleys, a timing belt, and a carriage motor. The pair of timing pulleys are disposed in the vicinity of both ends of the rear carriage guide shaft 14. The timing belt is spanned between the pair of timing pulleys, and a part of the timing belt is fixed to the carriage 11. The driving force of the carriage motor is transmitted to one timing pulley. When the carriage motor is driven, one timing pulley rotates and the timing belt moves. As a result, the carriage 11 moves along the pair of carriage guide shafts 14.

(Head unit moving mechanism)
FIG. 8 is a perspective view of the head unit moving mechanism 19. FIG. 9 is an explanatory view of the raising / lowering operation of the head unit 12 by the head unit moving mechanism 19. As shown in FIG. 8, the head unit moving mechanism 19 is disposed above the frame 76 having a support shaft 76a extending toward the rear Y2 of the printer, the operation lever 77 extending in the printer width direction, the support shaft and the operation lever. Further, an eccentric cam 78, a cam drive motor 19a serving as a drive source for the eccentric cam, and a coil spring 79 are provided.

  The operation lever 77 includes an operation portion 77a that can contact the operation portion 50 of the head unit 12 at an end portion in the first direction X1, and a long hole 77b at an end portion in the second direction X2. A support shaft 76a is inserted into the long hole 77b. A cam follower portion 77 c that contacts the cam surface (outer peripheral surface) of the eccentric cam 78 is provided between the operation portion 77 a and the long hole 77 b in the operation lever 77. A locking portion 77d of the coil spring 79 is provided in a portion between the cam follower portion 77c and the long hole 77b and close to the long hole 77b. The coil spring 79 is bridged between the locking portion 77d and a locking portion 76b provided at the upper end edge of the frame 76. The coil spring 79 urges the operation lever 77 upward to abut the cam follower portion 77c with the eccentric cam 78.

  When the cam drive motor 19a is driven, the eccentric cam 78 rotates. As the eccentric cam rotates, the cam follower portion 77c that slides on the cam surface moves in the vertical direction. As a result, the operating lever 77 has a lever raising position 77A in which the operating portion 77a is positioned above the rotation center shaft 78a of the eccentric cam 78, as shown in FIG. Further, the operation portion 77a moves between the lever lowering positions 77B located below the rotation center shaft 78a of the eccentric cam 78. In the initial state of the head unit moving mechanism, the operation lever 77 is positioned at the lever raised position 77A.

  As shown in FIG. 9A, when the carriage 11 is disposed at the opposed position 11A, when the cam drive motor 19a is driven and the operation lever 77 disposed at the lever raised position 77A is lowered, The operation portion 77a comes into contact with the operation unit 50 of the head unit 12 and pushes the head unit 12 downward. As a result, the head unit 12 arranged at the unit raised position 12 </ b> A moves downward against the urging force of the coil spring 75. Until the operation lever 77 is disposed at the lever lowered position 77B, the head unit 12 is disposed at the unit lowered position 12B as shown in FIG. 9B.

  When the head unit 12 is arranged at the unit lowered position 12B, the three spheres 23 to 25 held by the gap forming unit 22 come into contact with both the head unit 12 and the platen unit 17, and the print head 8 and the platen A platen gap G having a set distance (second distance) L2 is formed between the surface 17a. Here, when the platen gap G is formed, if the pushing force of the head unit 12 toward the platen unit 17 via the operation lever 77 is excessive, the operation lever 77 is applied to the support shaft 76a. It moves relative to it and misses its excessive power. That is, when the operation lever 77 is arranged at the lever lowering position 77B, the long hole 77b extends upward, and the portion of the operation lever 77 near the long hole 77b can be displaced in the vertical direction. Thus, the coil spring 79 is supported. Therefore, when the pushing force of the head unit 12 toward the platen unit 17 by the operation lever 77 is excessive, the end portion in the second direction X2 of the operation lever 77 in which the long hole 77b is formed is supported. It moves downward relative to the shaft 76a to release an excessive force applied to the head unit 12.

  Here, when the cam drive motor 19a is driven from the state shown in FIG. 9B, the operation lever 77 returns from the unit lowered position 12B to the lever raised position 77A shown in FIG. 9A. The head unit 12 is raised by the biasing force of the coil spring 75 while the operation lever 77 is raised toward the lever raised position 77A. Accordingly, when the operation lever 77 returns to the lever raised position 77A, the head unit 12 returns to the unit lowered position 12B.

(Platen unit)
FIG. 10 is a perspective view of the platen unit 17. The platen unit 17 includes guide rollers 36 a to 36 e, a belt driving roller 36 f that drives the conveyance belt 21, a unit main body 81 on which a conveyance motor 38 (see FIG. 3) is mounted, and four conveyance belts 21. . In the unit main body 81, horizontal belt portions 21 a of four transport belts 21 are stretched in the front-rear direction Y of the printer on the upper surface facing the head unit 12. The horizontal belt portion 21 a is a portion of the transport belt 21 that is stretched between the guide roller 36 c disposed at the front end portion of the unit main body 81 and the guide roller 36 d disposed at the rear portion of the platen unit 17. .

  The unit main body 81 is provided with three first to third platen side contact portions 82 to 84 that can contact the spheres 23 to 25 of the gap forming unit 22. The first platen side abutting portion 82 is provided at the front side portion of the edge of the unit main body portion 81 in the second direction X2. The second platen side abutting portion 83 is provided on the rear side portion of the edge of the unit main body 81 in the second direction X2. Here, a first plate member 85 made of metal that is long in the front-rear direction Y of the printer is attached to a side surface of the unit main body 81 in the second direction X2, and the first platen-side contact portion 82 and the second platen are attached. The side contact portion 83 is a metal plate portion that extends horizontally by bending at a substantially right angle from the upper end edge of the front end portion and the rear end portion of the first plate member 85 toward the inside where the horizontal belt portion 21a is located. 85a and 85b. The third platen side contact portion 84 is provided at the center portion in the printer front-rear direction Y of the edge of the unit main body 81 in the first direction X1. Here, a second plate member 86 made of metal that is long in the front-rear direction Y of the printer is attached to the side surface of the unit main body 81 in the first direction X1, and the third platen side abutting portion 84 is connected to the second plate member 86. The plate member 86 is a metal plate portion 86a that is bent at a substantially right angle and extends horizontally from the center portion in the printer front-rear direction Y of the plate member 86 toward the outer side opposite to the side where the horizontal belt portion 21a is located.

  The first platen-side contact portion 82, the second platen-side contact portion 83, and the third platen-side contact portion 84 are respectively the first carriage when the carriage 11 is disposed at the facing position 11A. The side contact portion 47, the second carriage side contact portion 48, and the third carriage side contact portion 49 are provided at positions facing each other. An imaginary plane defined by the first platen side contact portion 82, the second platen side contact portion 83, and the third platen side contact portion 84 is the platen surface 17a defined by the horizontal belt portion 21a. It is the same surface.

(Gap forming unit)
FIG. 11 is a perspective view showing a state in which the gap forming unit 22 is arranged on the platen unit 17. 12A is a plan view of the state in which the gap forming unit 22 is disposed on the platen unit 17, and FIG. 12B is a ZZ cross-sectional view (cross-sectional view of the spherical body holding portion) in FIG. 12A. is there. The support frame 26 has a substantially rectangular planar shape as a whole, and is disposed so as to overlap the platen surface 17 a of the platen unit 17. The support frame 26 includes a thin support frame main body portion 91 that overlaps the upper surface of the platen unit 17 and a support frame fixing portion 92 that is attached to the end of the support frame main body portion 91 on the printer rear Y2 side. The support frame 26 is fixed to the apparatus main body frame 20 (see FIG. 2) of the line printer 1 via a support frame fixing portion 92.

  The support frame main body 91 includes a pair of vertical frame portions 91a and 91b extending in parallel to the printer longitudinal direction Y along the left and right side surfaces of the platen unit 17, and five horizontal frames formed at regular intervals in the printer longitudinal direction Y. Frame portions 91c to 91g are provided. The horizontal frame portions 91c to 91g extend in parallel with the printer width direction X, and both ends thereof are connected to the vertical frame portions 91a and 91b. As shown in FIG. 11, the end portions of the vertical frame portions 91a and 91b on the printer rear Y2 side protrude further to the printer rear Y2 side than the horizontal frame portion 91g located closest to the printer rear Y2, and the support frame is provided here. A fixing portion 92 is attached.

  The support frame main body 91 is formed with three spherical body holding parts 93 to 95 that hold the three spherical bodies 23 to 25. The spherical body holding portions 93 to 95 are formed at positions overlapping the platen side contact portions 82 to 84. That is, the spherical body holding portion 93 that holds the spherical body 23 that is in contact with the first platen side contact portion 82 is the second direction of the front end of the support frame main body portion 91 to which the horizontal frame portion 91c and the vertical frame portion 91a are connected. It is formed at the corner of X2. The spherical body holding portion 94 that holds the spherical body 24 that comes into contact with the second platen side contact portion 83 has a second direction X2 at the rear end of the support frame main body portion 91 to which the horizontal frame portion 91g and the vertical frame portion 91a are connected. Are formed at the corners. The spherical body holding portion 95 that holds the spherical body 25 that is in contact with the third platen side contact portion 84 is formed at a position where the horizontal frame portion 91e is connected in the central portion of the vertical frame portion 91b in the front-rear direction Y of the printer. Yes.

  As shown in FIG. 12B, the sphere holding portion 93 is a wire support member that supports the penetration portion 96 that penetrates the vertical frame portion 91 a in the printer vertical direction Z and the sphere 23 that is inserted into the penetration portion 96. 97. The spherical body holding part 93 supports the spherical body 23 in a support state in a state in which the spherical body 23 can be slightly moved in the penetrating part 96 in the printer front-rear direction Y and the printer width direction X and can roll. Further, the support frame 26 supports the spherical body 23 in a state where the spherical body 23 is in contact with the first platen side contact portion 82. The structures of the spherical body holding portions 94 and 95 are the same as this. The three spheres 23 to 25 are identically shaped bearing balls having the same diameter.

  Here, the support frame 26 holds the star wheel 27 in addition to the spheres 23 to 25. The star wheel 27 abuts on the recording paper 6a conveyed on the platen surface 17a from above to prevent the recording paper 6a from floating. The star wheel 27 is attached at a position that does not overlap the line-type inkjet heads 41 to 44 of the print head 8 when the state in which the carriage 11 is disposed at the facing position 11A is viewed from the direction orthogonal to the platen surface 17a. Yes.

(Placement of print head at printing position and platen gap formation)
FIG. 13 is an explanatory diagram of the operation of arranging the print head 8 at the print position A. FIG. 14 and 15 are explanatory diagrams of the platen gap forming operation. When the line printer 1 is in the standby state, as shown in FIG. 13A, the carriage 11 is disposed at the standby position 11B. Accordingly, the print head 8 is located at the head standby position 8B and faces the head maintenance unit 18. The head unit 12 that holds the print head 8 is biased to the unit raised position 12A by a coil spring 75. When the line printer 1 is in a standby state for a long time, the head cap of the head maintenance unit 18 is raised and the ink nozzle surface 8a of the print head 8 is capped.

  When print data is supplied to the line printer 1, the carriage motor is driven. Thus, the carriage 11 moves in the second direction X2 along the carriage guide shaft 14 and is disposed at the facing position 11A shown in FIG. Here, since the head unit 12 is biased to the unit raised position 12A, the print head 8 moves in the second direction X2 while maintaining the gap with the platen unit 17 at the first distance L1, It is arranged at the head facing position 8A facing the platen unit 17.

  Here, the height dimension of the gap forming unit 22 in the longitudinal direction Y of the printer is shorter than the first distance L1. Therefore, the print head 8 does not collide with the gap forming unit 22 when the carriage 11 moves from the standby position 11B in the printer width direction X and is disposed at the facing position 11A.

  When the carriage 11 is arranged at the standby position 11B, as shown in FIG. 13B, the operation portion 50 of the operation lever 77 of the head unit moving mechanism 19 in which the operation unit 50 of the head unit 12 is at the lever raised position 77A. Located below. When the cam drive motor 19a is driven in this state, the operation lever 77 rotates downward and is disposed at the lever lowering position 77B. As a result, the head unit 12 moves in a direction approaching the platen unit 17 and is disposed at the unit lowered position 12B as shown in FIG.

  When the head unit 12 is arranged at the unit lowered position 12B, as shown in FIG. 13C, the spheres 23 to 25 of the gap forming unit 22 are moved to the carriage side contact portions 47 to 49 and the platen side contact portions 82 to. 84 abuts both. At this time, if the pushing force of the head unit 12 toward the platen unit 17 by the head unit moving mechanism 19 is excessive, the end portion of the operation lever in the second direction in which the long hole 77b is formed. Moves downward with respect to the support shaft 76a, and an excessive force applied to the head unit 12 is released. Thereby, the biasing force of the platen unit 17 by the head unit moving mechanism 19 is maintained at an appropriate level.

  Here, as shown in FIGS. 14 and 15, while the head unit 12 moves from the unit raised position 12 </ b> A to the unit lowered position 12 </ b> B, the first lower guide roller 60 has a diameter of the first lower guide roller 60. The first groove portion 69a of the first guide groove 69 having a width dimension substantially the same as the dimension is moved. The second guide roller 62 moves in the first groove portion 70a of the second guide groove 70 having a width dimension substantially the same as the diameter dimension of the second guide roller 62, and the third lower guide roller 63 is 3 The first groove portion 73a of the third guide groove 73 having a width dimension substantially the same as the diameter dimension of the lower guide roller 63 is moved. Therefore, the head unit 12 does not move in the printer width direction X and the printer front-rear direction Y on the carriage frame 13 while moving from the unit raised position 12A to the unit lowered position 12B.

  On the other hand, while the head unit 12 moves from the unit raised position 12 </ b> A to the unit lowered position 12 </ b> B, the first upper guide roller 61 has a second guide groove 69 that is wider than the diameter of the first upper guide roller 61. The groove part 69b is moved. Accordingly, as shown in FIG. 15A, the first upper guide roller 61 is movable in the front-rear direction Y of the printer in the second groove portion 69b, and the head unit 12 is moved on the carriage frame 13 in the first direction. The printer can be tilted in the front-rear direction Y of the printer around the rotation axis of the lower guide roller 60. Further, while the head unit 12 moves from the unit raised position 12 </ b> A to the unit lowered position 12 </ b> B, the third upper guide roller 64 has a second guide groove 73 that is wider than the diameter of the third upper guide roller 64. The groove part 73b is moved. Accordingly, as shown in FIG. 15B, the third upper guide roller 64 is movable in the printer width direction X in the second groove portion 73b, and the head unit 12 is moved to the third lower side on the carriage frame 13. It can be inclined in the printer width direction X around the rotation axis of the guide roller 63. Therefore, when the spheres 23 to 25 of the gap forming unit 22 are in contact with both the carriage side contact portions 47 to 49 and the platen side contact portions 82 to 84, the reference surface 12a and the platen surface 17a of the head unit 12 are parallel to each other. If not, the posture of the head unit 12 is corrected by the contact between the head unit 12 and the three spheres 23 to 25, and the reference surface 12a and the platen surface 17a of the head unit 12 become parallel.

  As a result, the gap between the reference surface 12a of the head unit 12 and the platen unit 17 is equal to the diameter of the spheres 23 to 25, and the platen gap G between the print head 8 and the platen unit 17 is It becomes constant at the second distance L2 shorter than the diameter of 23 to 25.

  When the platen gap G is the second distance, printing by the print head 8 is possible. Accordingly, the line printer 1 performs the conveyance operation for conveying the recording paper 6a at a constant speed by the paper conveyance mechanism 35 and the printing operation for performing printing by driving the print head 8 to be conveyed at the printing position A. Printing is performed on the surface of the recording paper 6a.

  When printing of the print data is completed, the print head 8 is returned to the head standby position 8B. That is, when printing of the print data is completed, the cam drive motor 19a is driven, and the operation lever 77 is returned to the lever raised position 77A. Thereby, the head unit 12 is raised by the urging force of the coil spring 75, and is arranged at the unit raised position 12A as shown in FIG. 13 (b). Thereafter, the carriage motor is driven in the reverse direction, and as shown in FIG. 13A, the carriage 11 returns from the facing position 11A to the standby position 11B. As a result, the print head 8 is disposed at the head standby position 8B facing the head maintenance unit 18.

(Function and effect)
In this example, the carriage 11 is moved from the standby position 11B to the facing position 11A while the head unit 12 is disposed at the unit raised position 12A. The head unit 12 is lowered from the unit raised position 12A to the unit lowered position 12B at the standby position 11B. Therefore, when the print head 8 at the head standby position 8B is moved to the head facing position 8A facing the platen unit 17, the gap between the print head 8 and the platen unit 17 is set to the first distance L1 having a long distance. be able to. Therefore, even when a paper floating prevention member such as the gap forming unit 22 or the star wheel 27 is disposed on the platen unit 17, it is possible to prevent these and the print head 8 from colliding with each other. Further, after the print head 8 has moved to a position facing the platen unit 17, the gap between the print head 8 and the platen unit 17 can be shortened. Therefore, this gap can be set to a distance suitable for printing.

  In this example, the head unit 12 is urged to the unit raised position 12A by the coil spring 75, and the head unit moving mechanism 19 moves the head unit 12 from the unit raised position 12A to the unit raised position against the urging force of the coil spring 75. It is moved to the lowered position 12B. Accordingly, it is easy to move the carriage 11 from the standby position 11B to the facing position 11A in a state where the head unit 12 is disposed at the unit raised position 12A. In other words, when the print head 8 at the head standby position 8B is moved to the head facing position 8A facing the platen unit 17, the gap between the print head 8 and the platen unit 17 is set to the long first distance L1. Easy to maintain. Further, since the urging force of the coil spring 75 acts on the head unit 12 moved to the unit lowered position 12B, the head unit 12 moved to the unit lowered position 12B can be easily returned to the unit raised position 12A. .

  Furthermore, in this example, the spheres 23 to 25 are supported by the support frame 26 so as to be able to roll, and are supported by the support frame 26 so as to be movable in the printer width direction and the printer front-rear direction. . Accordingly, when the head unit 12 and the platen unit 17 are brought into contact with the spheres 23 to 25, the posture of the head unit 12 changes and the reference surface 12a of the head unit 12 and the platen surface 17a are made parallel. It is easy to move the spheres 23 to 25 with respect to the head unit 12, and it is easy to move the spheres 23 to 25 with respect to the platen unit 17. As a result, the friction between the spheres 23 to 25 and the head unit 12 and the friction between the spheres 23 to 25 and the platen unit 17 are reduced, so that the head unit 12 and the platen unit 17 are worn when the platen gap G is formed. It is easy to prevent or suppress the occurrence.

  Further, in this example, when the head unit 12 is disposed at the unit lowered position 12 </ b> B, the head unit moving mechanism 19 pushes the head unit 12 toward the platen unit 17. Therefore, the posture of the head unit 12 can be changed by the pushing force by the head unit moving mechanism 19, and the reference surface 12a of the head unit 12 and the platen surface 17a can be made parallel. Further, the state in which the platen gap G is formed by the pushing force of the head unit moving mechanism 19 can be maintained.

(Modification)
In the above example, the spheres 23 to 25 are disposed between the head unit 12 and the platen unit 17, and the platen gap G is formed by bringing the head unit 12 and the platen unit 17 into contact with these spheres 23 to 25. However, instead of the sphere, at least one of the head unit 12 and the platen unit 17 is brought into contact with the other when the head unit 12 is disposed at the unit lowered position 12B. You may provide the gap formation protrusion which makes the gap between them constant. In this case, it is desirable to provide the gap forming protrusions at three locations where the spheres 23 to 25 are arranged.

  In the above example, when the head unit 12 and the platen unit 17 come into contact with the spheres 23 to 25, the posture of the head unit 12 changes. However, the posture of the platen unit 17 is changed. The reference surface 12a of the head unit 12 and the platen surface 17a may be parallel. In this case, it is possible to employ a configuration in which a platen unit frame that supports the platen unit 17 in a state in which the posture of the platen unit 17 can be changed is provided, and the platen unit frame is fixed to the apparatus main body frame 20 or the like. .

1. Line printer, 2. Printer housing, 2a ... Front, 3. Operation panel, 4. Paper exit, 5. Open / close lid, 6. Roll paper, 6a ... Recording paper, 7. ..Roll paper storage section, 8 ..Print head, 8a ..Ink nozzle surface, 8A ..head facing position, 8B ..head standby position, 9 ..paper transport path, 9a. 9b, second paper transport path, 9c, third paper transport path, 9d, fourth paper transport path, 11, carriage, 11A, opposing position, 11B, standby position, 12 · Head unit, 12a · · Reference plane, 12A · · Unit raised position (first position), 12B · · Unit lowered position (second position), 13 · · Carriage frame (frame), 14 · · Carriage guide shaft, 15 .. Carriage moving mechanism, 17 .. Platen (Platen), 17a ... Platen surface, 18. Head maintenance unit, 19. Head unit moving mechanism, 19a ... Drive motor for cam, 20 .... Main body frame, 21 ... Conveyor belt, 21a ... · Horizontal belt portion, 22 ·· Gap forming unit, 23 to 25 · · Sphere, 26 · · Support frame, 27 · · Star wheel, 31 · · Paper feed roller, 32 · · Tension lever, 32a · · Tension lever Center of rotation, 33... Paper guide, 35.. Paper transport mechanism, 36 a to 36 e.. Guide roller, 36 f.. Belt drive roller, 37 a, 37 b ... Pinch roller, 38 ... Transport motor, 41 ... Line-type inkjet head, 45 .. Bottom plate part, 45 a .. Opening part, 45 b to 45 d. 5f..Projection part, 45g..End edge part, 46..Square tube part, 47 to 49..Carriage side contact part, 47a to 49a..Lower end surface of carriage side contact part, 50..Operation part , 50a ... Contact part 51 ... First side wall part 52 ... Second side wall part 53 ... Third side wall part 54 ... Fourth side wall part 55a-55c ... Reinforcement plate 60 ... First lower guide roller 61 61 First upper guide roller 62 Second guide roller 63 Third lower guide roller 64 Third upper guide roller 65 First carriage Frame portion 66... Second carriage frame portion 67.. Third carriage frame portion 68.. Fourth carriage frame portion 69... First guide groove 69 a. 2 groove part, 70 ・ ・ Second guide Groove 70a ··· first groove portion 70b ··· first groove portion 71 ·· front support portion 72 ·· projection portion 73 ··· third guide groove 73a · · · first groove portion 73b ··· Second groove portion 74 ··· Rear support portion 75 · · Coil spring (biasing member), 76 · · Frame, 76a · · Support shaft, 76b · · Locking portion 77 · · · Operation lever 77a · · · Operation part, 77b ... Long hole, 77c ... Cam follower part, 77d ... Locking part, 77A ... Lever raised position, 77B ... Lever lowered position, 78a ... Rotary shaft, 78 ... Eccentric cam , 79 .. Coil spring, 81 .. Unit main body part, 82 to 84... Platen side contact part, 85 .. First plate member, 85 a, 85 b .. Metal plate part, 86 .. Second plate member, 86 a ..Metal plate part, 91..Support frame main body part, 91a, 91b , 91c to 91g .. side frame portion, 92 .. support frame fixing portion, 93 to 95 .. sphere holding portion, 96 .. penetrating portion, 97 .. support member, A .. printing position, G. Gap, X ·· Printer width direction, X1 · · Printer width direction first direction, X2 · · Printer width direction second direction, Y · · Printer front and rear direction, Y1 · · Printer front, Y2 · · Printer rear, Z. Up / down direction of printer

Claims (9)

A print head;
The platen,
A head unit that holds the print head, a first position where a gap between the print head and the platen is a first distance, and a second position where the gap is a second distance shorter than the first distance. A carriage including a frame that movably supports the head unit between
A carriage moving mechanism for moving the carriage between a facing position where the print head and the platen face each other and a standby position where the print head and the platen do not face each other;
A head unit moving mechanism that moves the head unit arranged at the first position to the second position when the carriage is arranged at the facing position;
A line printer comprising: In claim 1,
The line printer, wherein the head unit moving mechanism moves the carriage in a direction orthogonal to a facing direction of the print head and the platen. In claim 1,
The carriage includes a biasing member that biases the head unit to the first position,
The line printer according to claim 1, wherein the head unit moving mechanism moves the head unit from the first position to the second position against a biasing force of the biasing member. In any one of claims 1 to 3,
The line printer, wherein the second position is a position where printing can be performed on a recording sheet on the platen by the print head. In claim 4,
A gap forming member for making a gap between the print head and the platen constant;
The line printer, wherein when the head unit is disposed at the second position, the gap forming member abuts both the carriage and the platen. In claim 4,
At least one of the head unit and the platen has a gap-forming protrusion that makes contact with the other when the head unit is disposed at the second position and makes a gap between the print head and the platen constant. Line printer characterized by being provided with a section. In claim 5 or 6,
The carriage includes a guide mechanism for guiding the movement of the head unit;
The line printer comprising: a guide groove provided in one of the head unit and the frame; and a guide roller provided in the other and inserted into the guide groove. In claim 7,
The guide groove extends in a facing direction between the print head and the platen, and has a first groove width dimension substantially the same as the width dimension of the guide roller in order from the side close to the platen. 1 groove portion, and a second groove portion having a second groove width dimension longer than the first groove width dimension,
The guide roller includes a first guide roller and a second guide roller arranged in this order from the side close to the carriage in the facing direction,
When the head unit moves between the first position and the second position, the first guide roller moves in the first groove portion, and the second guide roller moves in the second groove portion. Line printer characterized by doing. A print head at a head standby position that does not face the platen is moved in a state where the gap between the platen and the print head is maintained at the first distance, and is arranged at a head facing position that faces the platen;
The line is characterized in that the print head is moved in a direction approaching the platen at the head facing position so that the gap between the print head and the platen is a second distance shorter than the first distance. How to move the print head of the printer.

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