JP6213154B2 - Inkjet recording device - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that can accurately form a gap between a print head and a platen.

  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. The print head is supported by the head frame in a state where each line-type inkjet head is fixed to the head fixing member.

  When the print head is an ink jet head, the print quality deteriorates unless the gap between the print head and the platen is maintained at a predetermined value at a predetermined distance. Therefore, in the line printer of Patent Document 1, the head frame is provided with a columnar protrusion protruding toward the platen side, and the circular lower end surface of the protrusion is brought into contact with the platen surface (the surface facing the print head). A gap having a distance corresponding to the height dimension of the protrusion is formed.

JP 2011-025479 A

  As in Patent Document 1, in a configuration in which a gap is formed by bringing a protrusion protruding from the side of a head unit on which a print head is mounted into contact with the platen surface, a reference surface (the head unit is mounted) set on the head unit. If the platen surface and the platen surface are not parallel to each other, the contact between the projection and the platen surface changes the posture of at least one of the head unit and the platen. The reference surface and the platen surface are made parallel.

  Here, when the posture of the head unit or the platen changes due to the contact between the protrusion and the platen surface, the protrusion moves on the platen surface as the posture changes. At this time, if the protrusions do not slide (not move) on the platen surface, the reference surface of the head unit and the platen surface cannot be made parallel. However, when the protrusion slides on the platen surface, there is a problem that when the operation for forming the gap is repeated, the protrusion or the platen surface is worn, and an accurate gap cannot be formed.

  In view of the above, an object of the present invention is to propose an ink jet recording apparatus that forms a gap between a print head and a platen accurately at a predetermined interval.

  In order to solve the above-described problems, an inkjet recording apparatus of the present invention includes a platen that faces a print head, a head unit that holds the print head, and the head unit and the platen. And a sphere that is in contact with the platen and has a constant gap between the print head and the platen.

  In the present invention, a sphere is arranged between the head unit and the platen in order to make the gap between the print head and the platen constant. Here, the spherical body has a small contact area with other members. Therefore, when the sphere, the head unit, and the platen are brought into contact with each other, the reference surface set on the head unit and the platen surface are not parallel to each other, and the posture of at least one of the head unit and the platen is changed by the contact. When the reference surface of the head unit and the platen surface are parallel, the sphere is easily slidable with respect to the head unit, and the sphere is easily slidable with respect to the platen. Therefore, it is possible to prevent or suppress the head unit and the platen from being worn when forming the gap. Therefore, even when the operation for forming the gap is repeated, the predetermined gap can be accurately formed.

  In this invention, it is desirable to have a holding | maintenance frame which hold | maintains the said spherical body so that rolling is possible. In this way, since the sphere rolls, if the posture of at least one of the head unit and the platen changes due to contact with the sphere, and the reference plane of the head unit and the platen surface are parallel, the sphere Easily moves relative to the head unit, and the sphere easily moves relative to the platen. As a result, since the friction between the sphere and the head unit and the friction between the sphere and the platen are reduced, it is possible to prevent or suppress the occurrence of wear on the head unit and the platen when the predetermined gap is formed.

  In the present invention, it is preferable that the holding frame holds the sphere so as to be movable in a direction intersecting a facing direction in which the print head and the platen are opposed to each other. In this way, when the attitude of at least one of the head unit and the platen changes due to contact with the sphere, and the reference surface of the head unit and the platen surface are parallel, the sphere rolls with respect to the head unit. It moves while moving, and the sphere moves while rolling with respect to the platen. As a result, since the friction between the sphere and the head unit and the friction between the sphere and the platen are further reduced, it is possible to prevent or suppress the occurrence of wear on the head unit and the platen when the predetermined gap is formed.

In the present invention, at least three of the spheres are spaced apart from each other,
The holding frame preferably holds each sphere at a position different from a straight line connecting the other two spheres. If the head unit and the platen are brought into contact with the three spheres held in such a position, it becomes easy to make the reference surface and the platen surface of the head unit parallel to each other.

  In this case, in order to hold the sphere in any rollable state, the sphere holder penetrates in the facing direction in which the print head and the platen face each other, and the sphere is partially inserted. A through hole, and a support member that spans the opening edge of the opening on one side of the through hole in the facing direction so as to cross the opening and can contact the sphere from the one side. It is desirable.

  In the present invention, there is provided a moving mechanism for moving the head unit between a first position where the gap is a first distance and a second position where the gap is a second distance shorter than the first distance. Preferably, the holding frame holds the sphere in contact with the platen, and the head unit contacts the sphere when arranged at the second position. If it does in this way, it will become easy to contact the spherical body arrange | positioned between a head unit and a platen, and a head unit and a platen.

  In the present invention, it is desirable to have a biasing mechanism that biases one of the head unit and the platen to the other through the sphere. In this way, when the reference surface set on the head unit and the platen surface are not parallel when the head unit and the platen are brought into contact with the sphere, the head unit and the platen are urged by the urging force of the urging mechanism. The reference plane of the head unit and the platen surface can be made parallel by changing the posture of at least one of the platens. Moreover, the state where the predetermined gap is formed by the urging force of the urging mechanism can be maintained.

  In the present invention, the sphere is preferably a metal sphere. For example, if a metal ball is used as a bearing ball, since the dimensional accuracy is high, it is easy to set the gap to a predetermined value.

  In the present invention, it is desirable that the platen has a contact portion made of metal in contact with the sphere. In this way, it is possible to reliably prevent the platen from being worn.

In the present invention, a platen support mechanism that supports the platen so as to be movable between a reference position facing the print head and a separation position different from the reference position,
The holding frame is arranged at a position where the sphere comes into contact with the platen when the platen is arranged at the reference position, and when the platen is arranged at the separated position, the sphere and the platen are arranged. It is desirable that the two are separated from each other. In this way, when the recording paper is jammed between the holding frame and the platen, the platen is moved from the reference position to the separated position, thereby separating the holding frame and the platen. The recording paper causing the paper jam can be removed. Further, since the sphere is held by the holding frame so as to be able to roll, when the platen is moved from the reference position to the separated position, the friction between the sphere and the platen, or the recording paper causing the sphere and the paper jam The friction is reduced. Therefore, it is easy to move the platen to the separation position, and it is easy to remove the jammed recording paper.

  According to the present invention, the sphere disposed between the head unit and the platen in order to form the gap has a small contact area with other members. Therefore, when the sphere, the head unit, and the platen are brought into contact with each other, the reference surface set on the head unit and the platen surface are not parallel to each other, and the posture of at least one of the head unit and the platen is changed by the contact. When the reference surface of the head unit and the platen surface are parallel, the sphere is easily slidable with respect to the head unit, and the sphere is easily slidable with respect to the platen. Therefore, it is possible to prevent or suppress the occurrence of wear on the head unit and the platen when forming the gap. Therefore, even when the operation for forming the gap is repeated, the predetermined gap can be accurately formed.

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 at the unit raising position. It is explanatory drawing of the state by which the head unit is arrange | positioned at the unit lowering position.

  A line printer as an embodiment of an ink jet recording apparatus to which the present invention is applied will be described below 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 printer front-rear direction Y), and a printer from the upper end of the first paper conveyance path portion 9a. A second paper transport path portion 9b that curves forward Y1 (front in the printer longitudinal direction Y), and a third paper transport path portion 9c that gently descends from the front end of the second paper transport path portion 9b toward the printer front Y1. The fourth paper transport path portion 9d extends horizontally from the front end of the third paper transport path portion 9c to the front Y1 of the printer.

  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 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. Above the carriage 11, a head unit moving mechanism (biasing mechanism / moving mechanism) 19 that lowers the head unit 12 when the carriage 11 is disposed at the facing position 11 </ b> A is disposed.

  The platen unit 17 has a horizontal platen surface 17a. The platen surface 17a is constituted by a horizontal belt portion 21a of the conveyance belt 21 described later. The platen unit 17 is supported by the platen support mechanism 16 so as to be movable between a reference position 17A facing the print head 8 and a separation position 17B spaced from the reference position 17 forward Y1 and downward of the printer. The state in which the platen unit 17 is disposed at the reference position 17A is the state indicated by the solid line in FIG. 2, and the platen surface 17a defines the fourth paper transport path portion 9d. The state in which the platen unit 17 is disposed at the separation position 17B is a state indicated by a dotted line in FIG. 2, and the platen unit 17 projects forward from the printer housing 2 in which the opening / closing lid 5 is opened.

  The platen support mechanism 16 includes, for example, a pair of guide rails that support the platen unit 17 from both sides in the printer width direction X and guide the movement of the platen unit 17 between the reference position 17A and the separation position 17B. . In the following, it is assumed that the platen unit 17 is disposed at the reference position 17A. The case where the platen unit 17 is arranged at the separation position 17B is a case where the jammed recording paper 6a is removed when a paper jam occurs at the printing position A.

  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 three spheres 23 to 25 that make the platen gap G between the print head 8 and the platen unit 17 constant at a preset set distance. (Refer to 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 and a feeding operation by the paper feeding mechanism 35 are performed, and a cueing operation is performed in which the top of the recording paper 6 a is arranged at the printing position A by the printing head 8. 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 conveying operation, the print head 8 is driven and controlled to print on the surface of the recording paper 6a conveyed at the printing 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 contact 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 X). 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. The reference plane 12a is made (see FIGS. 14 and 15).

  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. 7, 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. 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 third 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. Four coil springs 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, a carriage moving mechanism 15 that moves the carriage 11 in the printer width direction X between the facing position 11A and the standby position 11B is the same as a mechanism for moving the print head in a general 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 includes a frame 76 having a support shaft 76a extending toward the rear side Y2 of the printer, an operation lever 77 extending in the printer width direction, a support shaft 76a, and an operation lever 77 above the operation lever 77. 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 78 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 of the 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 (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 (a reference surface of the platen unit 17) 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 a horizontal belt portion 21a. It is the same surface as the platen surface 17a defined by.

(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 holding 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 holding frame 26 includes a thin holding frame main body portion 91 that overlaps the upper surface of the platen unit 17 and a holding frame fixing portion 92 that is attached to the end of the holding frame main body portion 91 on the printer rear Y2 side. The holding frame 26 is fixed to the apparatus main body frame 20 (see FIG. 2) of the line printer 1 via a holding frame fixing portion 92.

  The holding frame main body 91 includes a pair of vertical frame portions 91a and 91b extending in parallel with 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 holding frame is here. A fixing portion 92 is attached.

  The holding 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 contacts the first platen side contact portion 82 is the second direction of the front end of the holding 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 82 has a second direction X2 at the rear end of the holding 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 spherical body holding portion 93 includes a circular through hole 96 that penetrates the vertical frame portion 91 a of the holding frame 26 in the printer vertical direction Z, and one side of the through hole 96 in the printer vertical direction Z. Two linear support members 97 spanning the opening edge of the (upper) opening so as to cross the opening, and the inner peripheral side from the opening edge of the other side (lower) opening of the through hole 96 An annular stopper 96a is provided. The inner diameter of the through hole 96 is longer than the diameter of the sphere 23, and the inner diameter of the opening on the inner peripheral side of the stopper 96 a is shorter than the diameter of the sphere 23. Therefore, the stopper 96a can contact the sphere 23 from below. The support member 97 is a wire and spans the opening edge of the opening on the other side (upper side) of the through hole 96 via the upper surface of the sphere 23. The support member 97 can contact the spherical body 23 from above. Thereby, the spherical body 23 is in a state where the central portion is inserted into the through hole 96. The sphere 23 is held by the sphere holder 93 so as not to jump out in the up-down direction Z of the printer. The spherical body holding portion 93 holds the spherical body 23 in a state in which the spherical body 23 can be slightly moved in the through-hole 96 in the printer front-rear direction Y and the printer width direction X, and can be rolled. The holding frame 26 holds 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 held by the holding frame 26 so that each sphere is arranged at a position avoiding the straight line connecting the other two spheres. The three spheres 23 to 25 are identically shaped bearing balls having the same diameter.

  Here, the holding 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 front-rear 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 operation lever 77 formed with the long hole 77b in the second direction X2 is formed. The end portion 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 70 a of the second guide groove 70 having a width dimension substantially the same as the diameter dimension of the second guide roller 62. The third lower guide roller 63 moves the first groove portion 73 a of the third guide groove 73 having a width dimension substantially the same as the diameter dimension of the third lower guide roller 63.

  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. As a result, 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 in the first direction on the carriage frame 13. 1 It is possible to incline in the longitudinal 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. As a result, as shown in FIG. 15B, the third upper guide roller 64 can move in the printer width direction X in the second groove portion 73b, and the head unit 12 moves on the carriage frame 13 in the third lower position. It can be inclined in the printer width direction X around the rotation axis of the side 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 changed and 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 are parallel to each other. Become. Here, when the posture of the head unit 12 is corrected by the contact between the head unit 12 and the three spheres 23 to 25, the spheres 23 to 25 do not move with respect to the head unit 12 and the platen surface 17a. The posture of the head unit 12 cannot be changed. On the other hand, in this example, as shown in FIG. 15, the spheres 23 to 25 are held on the holding frame 26 in a rollable state and move in the printer width direction X and the printer front-rear direction Y. It is held by the holding frame 26 in a possible state. As a result, the spheres 23 to 25 can easily move with respect to the head unit 12, and the spheres 23 to 25 can easily move with respect to the platen unit 17. Therefore, the posture of the head unit 12 is corrected promptly.

  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 reaches the second distance L2, printing by the print head 8 becomes 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)
According to this example, the spheres 23 to 25 arranged between the head unit 12 and the platen unit 17 in order to form the platen gap G have a small contact area with other members. Further, the spheres 23 to 25 are held by the holding frame 26 in a rollable state and are held by the holding frame 26 in a state in which they can move in the printer width direction X and the printer front-rear direction Y. Therefore, when the spheres 23 to 25, the head unit 12, and the platen unit 17 are brought into contact with each other and the posture of the head unit 12 is changed, the spheres 23 to 25 easily move with respect to the head unit 12 and 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. Occurrence can be prevented or suppressed. Therefore, even when the operation of forming the platen gap G is repeated, the predetermined platen gap G can be formed with good reproducibility.

  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 (biasing force) by the head unit moving mechanism 19, and the reference surface 12a and the platen surface 17a of the head unit 12 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.

  Further, in this example, the holding frame 26 holds the spheres 23 to 25 in contact with the platen unit 17, and the head unit moving mechanism 19 moves the head unit 12 from the unit raised position 12A to the unit lowered position 12B. The head unit 12 and the spheres 23 to 25 are brought into contact with each other by being lowered. Therefore, it is easy to bring the head unit 12 and the platen unit 17 into contact with the spheres 23 to 25 arranged between the head unit 12 and the platen unit 17.

  In this example, the spheres 23 to 25 are metal bearing balls and have high dimensional accuracy, so that the platen gap G can be easily set to a predetermined value.

  Furthermore, since the platen side contact portions 82 to 84 that contact the spheres 23 to 25 in the platen unit 17 are all metal plate portions 85a, 85b, and 86a, it is possible to reliably prevent the platen unit 17 from being worn.

  Further, in this example, when a paper jam occurs in which the recording paper 6a is jammed between the gap forming unit 22 and the platen unit 17 at the printing position A, the platen unit 17 disposed at the reference position 17A is moved to the separation position. The jammed recording paper 6a can be removed by moving to 18B. Here, the spheres 23 to 25 held by the gap forming unit 22 are in contact with the platen unit 17 disposed at the reference position 17A, but the spheres 23 to 25 roll to the holding frame 26. It is held in a state where it can be moved in the printer width direction X and the printer longitudinal direction Y. Accordingly, when the platen unit 17 is moved from the reference position 17A to the separation position 17B, friction between the spheres 23 to 25 and the platen unit 17 or friction between the spheres 23 to 25 and the recording paper 6a causing the paper jam is generated. Reduced. Therefore, the platen unit 17 can be easily moved to the separation position 17B, and the jammed recording paper 6a can be easily removed.

(Modification)
In the above example, there are three spheres arranged between the head unit 12 and the platen unit 17 in order to form the platen gap G, but four or more spheres may be arranged. Also in this case, the holding frame 26 holds each sphere so that it can roll and move in the printer width direction X and the printer longitudinal direction Y.

  In the above example, the posture of the head unit 12 changes. However, when the head unit 12 and the platen unit 17 are brought into contact with the spheres 23 to 25, the posture of the platen unit 17 is changed. Thus, the reference surface 12a of the head unit 12 and the platen surface 17a can be made parallel. In this case, for example, the platen support mechanism 16 supports the platen unit 17 in a state where the posture can be changed. Further, when the spheres 23 to 25, the head unit 12 and the platen unit 17 come into contact with each other, the platen unit 17 is urged toward the head unit 12 via the spheres 23 to 25, thereby the platen unit 17 side. You may comprise so that the attitude | position of may be changed.

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, 14 .. Carriage guide shaft, 15. Carriage moving mechanism, 16 ... Platen support mechanism, 1 .. Platen unit (platen), 17a .. Platen surface, 18 .. Head maintenance unit, 19 .. Head unit moving mechanism (biasing mechanism and moving mechanism), 19a .. Cam drive motor, 20. Frame 21 .. Conveying belt 21 a. Horizontal belt part 22. Gap forming unit 23 to 25 Spherical body 26 Holding frame 27 Star wheel 31 Paper feed roller 32 · Tension lever, 32a · · Tension lever rotation center axis, 33 · · Paper guide, 35 · · Paper transport mechanism, 36a to 36e · · Guide roller, 36f · · Belt drive roller, 37a, 37b · · Pinch roller 38..Conveyance motor, 41..Line type ink jet head, 45..Bottom plate, 45a to 45d. Opening portion, 45e, 45f, projecting portion, 45g, edge portion, 46, square tube portion, 47 to 49, carriage side contact portion, 47a to 49a, lower end surface of carriage side contact portion, 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 to 55c .. Reinforcement plate 60 .. First lower guide roller 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. 69b .. second groove part, 70... Second guide groove, 70 a... First groove portion, 70 b... First groove portion, 71... Front side support portion, 72... Projection portion, 73... Third guide groove, 73 a. Groove portion 73b ··· Second groove portion 74 · · Rear support portion 75 · · Coil spring 76 · · Frame 76a · Support shaft 76b · · Locking portion · · · 77 · · Operation lever 77a · · · Operation part, 77b ·· Long hole, 77c · · Cam follower portion, 77d · · Locking portion, 77A · · Lever raised position, 77B · · Lever lowered position, 78 · · Eccentric cam, 78a · · · Center of rotation Shaft, 79 ... Coil spring, 81 ... Unit body part, 82 to 84 ... Platen side contact part (contact part), 85 ... First plate member, 85a, 85b ... Metal plate part, 86 ... Second plate member, 86a, metal plate portion, 91, holding frame main body, 91 91b ··· Vertical frame portion, 91c to 91g · · Horizontal frame portion, 92 ··· Holding frame fixing portion, 93 to 95 · · Sphere holding portion, 96 · · Through hole, 96a · · Stopper, 97 · · Support member , A ... Printing position, G ... Platen gap, X ... Printer width direction, X1 ... Printer width direction first direction, X2 ... Printer width direction second direction, Y ... Printer front-back direction, Y1 ..Front of printer, Y2 ..Back of printer, Z ..Up / down direction of printer

Claims (7)

A platen facing a print head having a nozzle surface;
The print head is held, and the relative position with respect to the platen is between a first position where the gap between the nozzle surface and the platen is a first distance and a second position where the gap is shorter than the first distance. A moving head unit;
A sphere that contacts the head unit and the platen located in the second position;
A holding frame that holds the sphere in a rollable manner;
An ink jet recording apparatus comprising: In claim 1,
The holding frame holds the first sphere, the second sphere, and the third sphere as the sphere,
The ink jet recording apparatus, wherein the first sphere is held at a position different from a straight line connecting the second sphere and the third sphere. In claim 1 or 2,
An ink jet recording apparatus, wherein the platen moves to a reference position where the platen comes into contact with the sphere and a separated position separated from the sphere. In claim 3,
With the platen positioned at the reference position,
An ink jet recording apparatus, wherein the head unit moves to the second position. In any one of claims 1 to 4 ,
The inkjet recording apparatus, wherein the head unit positioned at the second position is biased toward the platen via the sphere. In any one of claims 1 to 4 ,
The inkjet recording apparatus, wherein the platen located at the reference position is urged toward the head unit through the sphere. In any one of claims 1 to 6 ,
The ink jet recording apparatus, wherein the sphere is a metal sphere.

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