JP2012218354A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a recording medium from contacting with a nozzle surface by a medium pressing part in recording, and prevent the medium pressing part from interfering with cleaning in cleaning.SOLUTION: The ink jet printer includes a head part having the nozzle surface, a head holding part, a platen part, a platen holding part, a moving mechanism of the head holding part and the platen holding part, and the medium pressing part for pressing the recording medium on the platen, and includes a press holding mechanism having an energizing part, an abutting member, a medium press holding part, a support flame, and first and second attracting members. When an interval (a head gap) between the nozzle surface and the platen part becomes a head gap for a recording time, the first and second attracting members are mutually attracted magnetically, and the medium pressing part projects beneath the nozzle surface. When the head gap becomes one for a non-recording (retracting) time, an attracting state of the first and second attracting members is released by action of an energizing spring and the abutting member, and the medium pressing part retracts above the nozzle surface.

Description

  The present invention relates to an ink jet printer provided with a medium pressing mechanism that suppresses floating of a recording medium to be conveyed.

  As an image recording apparatus, for example, an ink jet printer having an ink head having a nozzle surface on which a plurality of nozzles are formed and a platen that holds a recording medium at a position facing the nozzle surface is known. In such an ink jet printer, an image is recorded by ejecting ink from nozzles of an ink head onto a recording medium which is held and conveyed by a platen.

  In addition, such an ink jet printer generally cleans the nozzle surface by a moving mechanism that moves at least one of the ink head and the platen so as to change a head gap that is an interval between the nozzle surface and the platen. Cleaning mechanism. At the time of cleaning, after moving one of the ink head and the platen with respect to the other, the head gap at the time of retraction is a head gap wider than the head gap at the time of recording which is the head gap at the time of image recording by the moving mechanism. The cleaning mechanism is moved between the platen and the nozzle surface. Then, the cleaning mechanism is positioned at a position facing the nozzle surface, and the head cleaning is performed by removing dust such as paper dust and unnecessary ink adhering to the nozzle surface with a wiper or a suction mechanism provided in the cleaning mechanism. It is generally known. By such a cleaning operation, the inkjet printer can maintain the quality of image recording.

  In addition, in order to hold the recording medium in close contact with the platen, for example, in the case of a long continuous recording medium, a method of applying tension to the continuous recording medium so that the recording medium is in close contact with the platen is also cut in advance to a standard size. In the case of a recording medium, a method of adsorbing the recording medium with a fan or the like provided on the platen and an electrostatic adsorption method of adsorbing the recording medium using static electricity are known.

  However, even when the platen holds the recording medium in close contact with the above-described method, for example, when the recording medium is lifted from the platen if the adsorption force is insufficient or the recording medium is bent or the like. The recording medium comes into contact with the nozzle surface of the ink head. As a result, the ink head may be damaged, or unexpected ink may adhere to the recording medium and cause contamination.

  In order to cope with such a reason, for example, in Patent Document 1, the recording medium is lifted by pressing the recording medium against the platen in the vicinity of the ink head so that the recording medium floating from the platen does not contact the ink head. An ink jet printer provided with a medium pressing portion composed of a pressing roller for suppressing the above is disclosed.

Japanese Patent Laid-Open No. 10-329972

  In the ink jet printer described in Patent Literature 1, at least during image recording, a recording press gap, which is an interval between the medium press portion and the platen, needs to be equal to or greater than the thickness of the recording medium in order to press the recording medium. Further, the recording pressing gap needs to be smaller than the recording head gap so that the recording medium does not contact the nozzle surface. In the case where a means for bringing the recording medium into close contact with the platen, such as the suction fan as described above, is provided, the medium pressing portion does not necessarily need to contact and hold the recording medium, and the pressing gap during recording is the thickness of the recording medium. It is sufficient if the distance is smaller than the recording head gap.

  On the other hand, at the time of cleaning, in order to avoid interference between the cleaning mechanism and the medium pressing unit when the cleaning mechanism is moved between the nozzle surface of the ink head and the platen, the medium pressing unit and the platen at the time of retraction The retraction pressing gap, which is the interval, is preferably greater than or equal to the retraction head gap.

  In other words, at the time of image recording, the medium pressing portion protrudes from the nozzle surface of the ink head to the platen side to prevent the recording medium from coming into contact with the ink head. It is preferable to appropriately control the positions of the ink head and the medium pressing portion so that they do not protrude from the nozzle surface toward the platen side and do not interfere with cleaning.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an ink jet printer in which a recording medium does not come into contact with an ink head by a medium pressing portion during recording, and the medium pressing portion does not interfere with cleaning during cleaning.

  In one embodiment of the present invention, a head portion having a nozzle surface on which a plurality of nozzles are formed, a head holding portion that holds the head portion, and a nozzle surface that are disposed to convey a recording medium And a platen holding part that holds the platen, and a head gap that is an interval between the nozzle surface and the platen part is at least larger than a head gap during recording and a head gap during recording A moving mechanism for moving at least one of the head holding part and the platen holding part in order to change the head gap when retracted, and a medium pressing part for holding down the recording medium conveyed to the platen part. In the ink jet printer provided, an urging portion provided in the head holding portion and an abutting member attached to the urging portion are provided. The pressing gap, which is the distance between the medium pressing portion and the platen, is divided into a pressing gap during recording smaller than the head gap during recording and a pressing gap during retraction larger than the head gap during retraction. A medium press holding portion that holds the medium press holding portion movably, a support frame portion that is provided in the head holding portion and supports the medium press holding portion, and a first suction attached to the medium press holding portion. A holding member holding mechanism, and a second holding member provided on the platen holding unit so as to face the first holding member, and the moving mechanism sets the head gap at the time of recording. When at least one of the head holding part and the platen holding part is moved to form a head gap, the first and second suction members The medium pressing portion protrudes closer to the platen portion than the nozzle surface when they are magnetically attracted to each other and come into contact with each other, and the moving mechanism moves the head gap to the head gap when retracted. When at least one of the head holding portion and the platen holding portion is moved as described above, the abutting member comes into contact with the support frame portion, and the biasing force by the biasing portion is the first force. And the magnetic attraction force between the second attraction members works in the opposite direction and becomes larger than the magnetic attraction force, so that the attraction state of the first and second attraction members is released, and the medium presser The part is an ink jet printer that retracts to the head part side from the nozzle surface.

  According to the present invention, it is possible to provide an ink jet printer in which the recording medium does not come into contact with the ink head by the medium pressing portion during recording, and the medium pressing portion does not hinder cleaning during cleaning.

1A and 1B are side views schematically showing an ink jet printer of the present invention. 2A is a view of an image recording unit according to one aspect as viewed from above, and FIG. 2B is a view of the image recording portion according to one aspect as viewed from below. FIG. 3 is a view of an image recording unit according to another aspect as viewed from below. FIG. 4 is a cross-sectional view of the medium pressing roller. FIG. 5 is an exploded side view of the holding mechanism. 6A to 6C are side views schematically showing the operation of the holding mechanism. FIGS. 7A and 7B are side views showing a state where a normal gap and a wide gap are set as the head gap between the nozzle surface of the ink head and the platen. 8A to 8C are side views schematically showing the operation of the holding mechanism of the first modification. 9A to 9C are side views schematically showing the operation of the holding mechanism of the second modification. FIGS. 10A to 10C are conceptual diagrams showing one embodiment of a magnetic circuit. FIGS. 11A to 11D are conceptual diagrams showing other forms of the magnetic circuit. 12A and 12B are diagrams illustrating an image recording unit of Modification 3. FIGS. 13A and 13B are side views schematically showing the operation of the holding mechanism of the third modification. FIG. 14 is a side view schematically showing a holding mechanism of a fourth modification. FIGS. 15A and 15B are side views schematically showing a holding mechanism having another configuration. FIG. 16 is a side view schematically showing an adsorption member having another configuration.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram schematically showing an ink jet printer 1 of the present invention. FIG. 1A shows a state when the inkjet printer 1 is recording an image, and FIG. 1B shows a state when the inkjet printer 1 is not recording an image (when retracted). In the following description, the conveyance direction of the recording medium 2 is referred to as the X direction, the direction orthogonal to the X direction is referred to as the Y direction or the width direction, and the direction orthogonal to the X direction and the Y direction is referred to as the Z direction or the vertical direction.

  The ink jet printer 1 is roughly classified into a medium supply unit 11, an image recording unit 12, a transport unit 13, a lifting mechanism (moving mechanism) 14, a medium storage unit 15, and a control unit 16 that controls the entire ink jet printer. And is constituted by. Although only the components related to the gist of the present invention are shown in the drawings, the inkjet printer 1 has components included in a normal inkjet printer such as an ink supply mechanism and a cleaning mechanism (not shown). And

First, the medium supply unit 11 will be described.
The medium supply unit 11 is located on the most upstream side in the conveyance direction of the recording medium 2. The medium supply unit 11 includes a supply base 21, a supply roller 22, and a registration roller pair 23.

  The supply base 21 stores a plurality of recording media 2 such as recording paper and film. 1 (a) and 1 (b) show one supply base 21, but a plurality of recording media of various types (a plurality of types or a plurality of thicknesses) can be used. A supply stand 21 may be provided.

  The supply roller 22 is also called a pickup roller, and is disposed above the supply table 21 and adjacent to the supply table 21. The supply roller 22 comes into contact with the recording medium 2 stored in the supply table 21 and takes out the recording medium 2 in contact with the recording medium 2 one by one. The taken-out recording medium 2 is sent to the registration roller pair 23.

  The registration roller pair 23 is a roller pair for correcting (correcting) an inclination (skew) with respect to the conveyance direction (X direction) of the recording medium 2. The registration roller pair 23 includes a pair of upper and lower registration rollers 23a and 23b, and the support shafts of the registration rollers 23a and 23b are substantially parallel to each other. The upper registration roller 23a is urged toward the lower registration roller 23b by a spring (not shown) and is in contact with the registration roller 23b. In addition, the upper surface of the lower registration roller 23 b is disposed so as to be substantially flush with the conveyance path extension line of the recording medium 2.

  The registration roller pair 23 abuts the front end of the recording medium 2 supplied by the supply roller 22 to the nip portion of the registration roller pair 23 to correct (correct) the inclination (skew) with respect to the conveyance direction of the recording medium 2. Then, the recording medium 2 is conveyed to the conveying unit 13 in accordance with the image recording timing in the image recording unit 12 described later.

Next, the transport unit 13 will be described.
The transport unit 13 is disposed opposite to the image recording unit 12 on the downstream side in the transport direction from the medium supply unit 11. The transport unit 13 includes a transport belt 41, a platen 42, a suction fan 43, a drive roller 44, a driven roller 45, tension rollers 46 (46 a and 46 b), and a transport frame 47. .

  The conveyor belt 41 is formed in an endless belt shape, and a plurality of holes are provided on the surface thereof. The conveyor belt 41 is held in a state where a tension is applied by a driving roller 44, a driven roller 45, and a tension roller 46. The driving roller 44, the driven roller 45, and the tension roller 46 are rotatably held by the conveyance frame 47. Note that a motor (not shown) is connected to the drive roller 44, and the conveyance belt 41 rotates in a predetermined direction by driving the motor.

  A platen 42 and a suction fan 43 are provided below the conveyor belt 41. The platen 42 and the suction fan 43 are also held by the transport frame 47. That is, the conveyance frame 47 plays a role as a platen holding portion that holds the conveyance belt 41 and the platen 42 as platen portions. The platen 42 is processed so that at least a region facing the image recording unit 12 is a flat surface, and a plurality of holes are formed. The suction fan 43 is disposed below the platen 42 and is held by the transport frame 47. The suction fan 43 sucks air through the plurality of holes of the transport belt 41 and the platen 42. As a result, the recording medium 2 conveyed from the registration roller pair 23 is attracted onto the conveyance belt 41 and conveyed to the downstream side in the conveyance direction (medium storage unit 15) at a predetermined conveyance speed.

  The transport unit 13 is moved to a recording position shown in FIG. 1A and a retracted position shown in FIG.

Next, the medium storage unit 15 will be described.
The medium storage unit 15 is located on the most downstream side in the conveyance direction of the recording medium 2. The medium storage unit 15 includes a discharge roller pair 61 and a stocker 62. The discharge roller pair 61 discharges the recording medium 2 on which the image is recorded by the image recording unit 12 from the transport unit 13. The stocker 62 stores the recording medium 2 on which an image has been recorded.

Next, the image recording unit 12 will be described.
2A is a diagram of the image recording unit 12 as viewed from above, and FIG. 2B is a diagram of the image recording unit 12 as viewed from below.

  The image recording unit 12 includes, for example, a head unit 31 (31C, 31K, 31M, 31Y) that discharges ink of four colors of cyan (C), black (K), magenta (M), and yellow (Y), respectively. The head holding member 32 that holds the head portion 31 and the interval adjusting member 33 (33a, 33b, 33c, 33d) are provided.

  As shown in FIG. 2A and FIG. 2B, the head holding member 32 is provided with a plurality of openings 34. A plurality of ink heads 35 constituting the head portion 31 are respectively positioned and fixed in these openings 34. Thus, these ink heads 35 constitute a line head that is equal to or more than the recording area in which image recording is performed in the width direction of the recording medium 2.

A plurality of nozzles are formed in a row in the width direction of the recording medium 2 on the nozzle surface 35a of the ink head 35, and an image is recorded on the recording medium 2 by ejecting ink from these nozzles. In the present embodiment, the six ink heads 35 are alternately arranged in two rows (in a staggered pattern) so as to have a length equal to or greater than this width along the width direction of the recording medium 2. The line head is configured. At this time, the end portions of the ink head 35 (ends of the nozzle rows) are arranged so as to overlap each other when viewed from the transport direction. This overlap is for preventing streaky unrecorded areas (white stripes) when an image is recorded on the recording medium 2.
Of course, the number of the ink heads 35 is not limited to this, and the head unit 31 may be configured by one long ink head. Further, the ink head may be arranged in three or more rows.

  The spacing adjusting members 33 (33a, 33b, 33c, 33d) are provided at the four corners of the facing surfaces 32a of the head holding member 32 facing the platen 42 of the transport unit 13, as shown in FIG. Yes. Specifically, the spacing adjustment members 33a and 33c are provided on the upstream side in the transport direction on the facing surface 32a (upstream in the transport direction from the head portion 31C), and downstream in the transport direction (downstream in the transport direction from the head portion 31Y). Are provided with interval adjusting members 33b and 33d.

In the present embodiment, the interval adjusting member 33 is in the form of a pin formed so as to protrude toward the transport unit 13, and is in contact with the platen 42 of the transport unit 13. Thus, the interval between the image recording unit 12 and the transport unit 13 is set to a predetermined value. In other words, the interval adjusting member 33 is such that the interval (head gap) between the nozzle surface 35a of the head portion 31 (ink head 35) during image recording and the platen 42 of the conveying portion 13 is a predetermined recording head gap value. Regulate to be.
Further, the distance adjustment member 33 can be changed by the control unit 16 in an amount protruding downward from the nozzle surface 35a. That is, the interval adjusting member 33 can set a plurality of head gaps according to the thickness of the recording medium 2.

  Further, on the facing surface 32a side of the head holding member 32, as shown in FIG. 1 and FIG. 2B, a medium pressing roller 101 as a medium pressing portion for suppressing the floating of the recording medium 2 being conveyed. Is provided. In the present embodiment, the medium pressing roller 101 is a rod-shaped member extending in the width direction, and both ends thereof are rotatably supported by bearings 202 described later.

  In one mode shown in FIG. 1 and FIG. 2B, the medium pressing roller 101 is arranged on the upstream side in the transport direction of each head portion 31 (31C, 31K, 31M, 31Y). That is, four medium pressing rollers 101 are provided. However, the arrangement of the medium pressing roller 101 is not limited to this. For example, as in another mode shown in FIG. 3, the medium pressing roller 101 is arranged upstream of the row in the width direction of each ink head 35 constituting the line head. A configuration in which the rollers 101 are arranged (a configuration in which eight medium pressing rollers 101 are provided) may be used.

FIG. 4 is a cross-sectional view of the medium pressing roller 101.
The medium pressing roller 101 includes a belt contact portion 101a at both ends, an intermediate medium pressing portion 101b, and a held portion 101c that is rotatably held by a bearing 202 described later.

  The medium pressing roller 101 is set such that the width interval B between the medium pressing portions 101 b is equal to or larger than the width of the recording medium 2 conveyed by the conveying belt 41. Further, the distance C on the outer side in the width direction of the belt contact portion 101 a provided at both ends is set to be equal to or smaller than the width of the transport belt 41. Further, a gap A in the Z direction is formed between the outer peripheral surface of the belt contact portion 101a and the outer peripheral surface of the medium pressing portion 101b. That is, the radius of the belt contact portion 101a is larger by the gap A than the radius of the medium pressing portion 101b. In the present embodiment, for example, the gap A is set to about 0.5 mm, and the interval B is set to 297 mm or more so as to be able to pass through an A3 size recording medium.

  The medium pressing roller 101 rotates following the rotation of the conveyance belt 41 because the belt contact portion 101a contacts the conveyance belt 41 when the recording medium is conveyed. At this time, since the gap A is formed between the belt contact portion 101a and the medium pressing portion 101b, the medium pressing portion 101b is not in contact with the transport belt 41 within the interval B in the width direction. Therefore, if the recording medium 2 is normally attracted to the conveyance belt 41, the recording medium 2 can be passed through the surface of the medium pressing portion 101b of the medium pressing roller 101 in a non-contact manner.

  In addition, since the medium pressing roller 101 rotates following the rotation of the conveyance belt 41, even if the recording medium 2 comes into contact with the medium pressing roller 101, it is difficult to cause a conveyance load of the recording medium 2. Note that the frictional resistance of the medium pressing portion 101b with respect to the recording medium 2 may be intentionally increased. Thereby, even if the recording medium 2 comes into contact with the medium pressing roller 101, the recording medium 2 can be positively conveyed.

  The medium pressing roller 101 is not limited to the stepped shape as shown in FIG. 4, and for example, a straight medium pressing roller may be used. Further, instead of the medium pressing roller 101, a plate-shaped pressing member disposed to face the platen 42 may be provided.

Next, the configuration of the holding mechanism 200 that holds the medium pressing roller 101 between the image recording unit 12 and the transport unit 13 will be described.
FIG. 5 is an exploded side view of the holding mechanism 200. The holding mechanism 200 includes a bearing support frame 201, a bearing 202, a transport unit suction member 203, a biasing spring 204, a peeling projection 205, and a bearing suction member 206.

  A bearing support frame 201 as a support frame unit is fixed to the image recording unit 12 and extends downward (from the conveying unit 13 side) from the image recording unit 12. An urging spring 204 as an urging unit is located in the bearing support frame 201, one end side is fixed to the image recording unit 12 side, and the other end side is provided on the upper surface of the bearing 202 as a medium press holding unit. It is attached to a peeling protrusion 205 as an abutting member. The bearing 202 is always urged upward by a bearing support frame 201 and an urging spring 204 so as to be slidable in the vertical direction.

  The bearing 202 holds the medium pressing roller 101. In addition, a conveyance unit suction member 203 is attached to the lower surface of the bearing 202 that faces the upper surface where the peeling protrusion 205 is provided.

  The bearing suction member 206 is provided on the platen 42 side of the transport unit 13 facing the transport unit suction member 203. For example, one of the conveyance unit attracting member 203 and the bearing attracting member 206 may be a permanent magnet and the other may be a magnetic metal, or both may be a permanent magnet. Furthermore, an electromagnet may be used.

  When the conveying unit 13 is raised by the elevating mechanism 14 and approaches the conveying unit adsorbing member 203, the bearing adsorbing member 206 is more than the urging force of the urging spring 204 toward the image recording unit 12 with respect to the bearing 202. Is set so that the magnetic attraction force toward the conveying unit 13 (platen 42) with respect to the bearing 202 is increased. As described above, when the magnetic attraction force becomes larger than the urging force, the bearing attraction member 206 comes into close contact with the transport unit attraction member 203 and is held on the platen 42 side.

Next, the lifting mechanism 14 will be described.
The elevating mechanism 14 is a moving mechanism that moves the transport unit 13 (a platen unit including the transport belt 41 and the platen 42) to a recording position (FIG. 1A) and a retracted position (FIG. 1B). 2A, the elevating mechanism 14 includes a motor 51 as a drive source, four wires 52 (52a, 52b, 52c, and 52d), and a winding unit 53 that winds up the wires 52. And a winding shaft 54 that transmits the driving force of the motor 51 to the winding portion 53.

  The motor 51 is attached to the head holding member 32 and rotates a winding shaft 54 extending in the transport direction via a gear or the like (not shown). Four winding portions 53 for winding the respective wires 52a, 52b, 52c, and 52d are attached to the winding shaft 54. The winding unit 53 includes a pulley 55 and a torque limiter 56. One end of each wire 52a, 52b, 52c, 52d is fixed to the pulley 55. Moreover, the other end side of each wire 52a, 52b, 52c, 52d is being fixed to the conveyance part 13 mentioned above. As described above, the wires 52 (52a, 52b, 52c, 52d) are in a state in which the conveyance unit 13 is suspended from the image recording unit 12.

  When the winding shaft 54 rotates in a predetermined direction by the motor 51, the lifting mechanism 14 also rotates the winding portion 53 (pulley 55 and torque limiter 56) according to the rotation of the winding shaft 54, and each wire 52a, 52b, 52c and 52d are wound around the pulley 55 at the same time. At this time, the torque limiter 56 prevents excessive tension from acting on the wire 52 (52a, 52b, 52c, 52d). Thereby, when the wire 52 is wound by the winding portion 53, an excessive force is applied to the wire 52 to prevent it from being cut or stretched.

  In addition, when the conveyance unit 13 is brought into contact with the image recording unit 12 via the interval adjusting member 33, the conveyance unit 13 is held by the spring force of the torque limiter 56. Since the amount of force generated by the biasing spring 204 acts to assist the spring force of the torque limiter 56, the abutting state can be easily maintained by adopting such a configuration.

  In this embodiment, the lifting mechanism 14 moves (lifts) the transport unit 13 to change the interval between the head unit 31 (image recording unit 12) and the platen unit (transport unit 13). The method of changing the interval is not limited to this, and an elevating mechanism that moves the image recording unit 12 may be provided, or an elevating mechanism that moves both the image recording unit 12 and the conveying unit 13 may be provided. Good. That is, the elevating mechanism 14 may be configured to move at least one of the image recording unit 12 and the transport unit 13 and change the interval between the head unit 31 and the platen unit.

  In this embodiment, the mechanism for changing the interval between the head unit 31 (image recording unit 12) and the platen unit (conveying unit 13) is a mechanism for winding the wire 52, but the mechanism for changing the interval is Not limited to this, a mechanism using an operable arm or the like may be used, and any mechanism that changes the interval between the head unit 31 and the platen unit may be used.

Next, the recording operation of the ink jet printer 1 of this embodiment will be described.
First, an image recording instruction is input from an operation panel (not shown) of the inkjet printer 1, or an image recording instruction signal is input from a host device (not shown) connected by a signal line. In response to this instruction, the transport unit 13 is raised from the retracted position shown in FIG. 1B by the lifting mechanism 14 and moved to the recording position shown in FIG. At the recording position, when the transport unit 13 is raised by the elevating mechanism 14, the interval adjusting member 33 described above comes into contact with the platen 42, whereby the interval between the image recording unit 12 and the transport unit 13 becomes a predetermined interval. The distance between the nozzle surface 35 a and the platen 42 becomes a recording head gap according to the thickness of the recording medium 2.

  Thereafter, the supply roller 22 is driven while the registration roller pair 23, the drive roller 44, and the discharge roller pair 61 are driven. As a result, the uppermost recording medium 2 is taken out from the supply table 21 by the supply roller 22. Then, the taken-out recording medium 2 is transferred to a gripping portion formed by the facing portions of the registration rollers 23a and 23b of the registration roller pair 23.

  At this time, the rotation of the registration roller pair 23 is temporarily stopped by a registration clutch (not shown). By this temporary stop, the leading end portion of the recording medium 2 that has been transported to the registration roller pair 23 hits the grip portion, and once the travel is stopped and curved, the transported posture is corrected. That is, if there is skew in the recording medium 2, the skew is corrected. Thereafter, when a predetermined time elapses, the rotation restriction by the registration clutch is released, and the registration medium pair 23 is rotated, so that the recording medium 2 is fed onto the conveyance belt 41 of the conveyance unit 13 at a predetermined speed.

  The recording medium 2 fed onto the conveyor belt 41 is adsorbed to the conveyor belt 41 and the platen 42 by a suction force applied by the suction fan 43 through a plurality of holes formed in the conveyor belt 41 and the platen 42. In this state, it is transported in the X direction at a predetermined transport speed.

  The medium pressing roller 101 presses the recording medium 2 floating from the upper surface of the conveying belt 41 at least partially against the conveying belt 41 so that the recording medium 2 is reliably adsorbed to the conveying belt 41, and the recording medium 2 is Avoiding contact with the head portion 31.

Then, the recording medium 2 conveyed by the conveyance belt 41 passes below the head portions 31C, 31K, 31M, 31Y. During the passage, ink is appropriately ejected from the nozzles of the head portions 31C, 31K, 31M, and 31Y at a timing controlled by the control unit 16, and an image is recorded on the recording medium 2. In this way, the recording medium 2 on which the images of the respective colors are superimposed and recorded is discharged out of the printer 1 by the discharge roller pair 61 and stored in the stocker 62.
With the above operation, a series of image recording operations on the recording medium 2 is completed.

Next, the operation of the holding mechanism 200 in the present embodiment will be described.
FIG. 6A is a side view showing the press-holding mechanism 200 during standby (during non-image recording). In this state, the transport unit 13 (only the platen 42 is shown in FIGS. 6A to 6C) is in the retracted position retracted downward from the image recording unit 12 by the elevating mechanism 14. Then, the medium pressing roller 101 supported by the bearing 202 of the holding mechanism 200 is urged toward the image recording unit 12 (upward) by the urging spring 204, so that the nozzles of the image recording unit 12 are pressed. The surface is retracted above the surface 35a, that is, to the head portion side. That is, the medium pressing roller 101 is in a state where it does not protrude downward from the nozzle surface 35a.

  Here, if the gap between the nozzle surface 35a and the platen 42 is the head gap HG and the gap between the lower surface of the medium pressing roller 101 and the platen 42 is the pressing gap OG, the retracted state (standby state) shown in FIG. Then, HG <OG. As described above, in the retracted state, the medium pressing roller 101 serving as the medium pressing portion is retracted above the nozzle surface 35a of the head portion 31, so that a cleaning mechanism (not shown) is connected to the nozzle surface 35a and the platen for cleaning. When moving to the position 42, interference between the cleaning mechanism and the medium pressing portion can be avoided, and the cleaning operation can proceed smoothly.

  FIG. 6B is a side view showing the holding mechanism 200 when the transport unit 13 is raised by the elevating mechanism 14 before starting image recording (at the start of image recording). When the transport unit 13 is raised by the elevating mechanism 14 and approaches the nozzle surface 35a of the image recording unit 12, the transport unit suction member 203 is attracted to the transport unit 13 by the magnetic attracting force from the rising bearing suction member 206. It is done. As a result, the bearing 202 to which the conveying unit suction member 203 is attached and the medium pressing roller 101 held by the bearing 202 are also attracted downward. Then, as shown in FIG. 7A, the conveyance unit adsorption member 203 and the bearing adsorption member 206 are magnetically adsorbed to each other and come into an adsorbed state. Thereby, the relationship between the head gap HG and the holding gap OG is HG> OG. Of course, the head gap at this time is smaller than the head gap at the time of retraction.

  Thus, the recording head gap set at the start of image recording is changed according to the thickness of the recording medium 2 conveyed by the conveying unit 13 by changing the protruding amount of the interval adjusting member 33 as described above. be able to. FIG. 7A shows a state in which a recording head gap (normal head gap) is set in the case of the recording medium 2 having a normal thickness after the state shown in FIG. 6B. ) Shows a state in which a recording head gap (wide head gap) is set in the case of a relatively thick recording medium 2.

  In any case, the relationship between the recording head gap, which is the head gap HG during image recording, and the recording pressing gap, which is the pressing gap OG during image recording, is HG> OG, and the medium pressing roller 101 is the head. The portion 31 protrudes downward from the nozzle surface 35a, that is, to the platen side. In addition, the pressing gap during recording is equal to or greater than the thickness of the recording medium 2 in order to suppress the floating of the recording medium 2. In such a state, during image recording, the medium pressing roller 101 can prevent the conveyed recording medium 2 from floating from the platen 42 and can restrict the recording medium 2 from coming into contact with the nozzle surface 35a. .

  Here, when a wide recording head gap as shown in FIG. 7B is set, the magnetic attraction force between the conveyance unit adsorbing member 203 and the bearing adsorbing member 206 described with reference to FIG. 6B. There is a possibility that the suction state of these suction members 203 and 206 cannot be created. Therefore, when setting a wide head gap, the suction unit is set in order to set the normal head gap shown in FIG. A wide head gap may be created by changing the protruding amount of the interval adjusting member 33.

  When recording an image, it is possible to assist the force with which the conveying mechanism 13 is applied by the elevating mechanism 14 with the upward force by the urging spring 204. This is very important for maintaining the recording state. Is advantageous.

  FIG. 6C is a side view showing the presser holding mechanism 200 when the image recording state shifts to the retracted state. When the transport unit 13 is retracted downward by the elevating mechanism 14, the transport unit suction member 203 and the bearing suction member 206 are held in the bearing 202 and the bearing 202 to which the transport unit suction member 203 is attached while the transport unit suction member 203 and the bearing suction member 206 are in the suction state. The medium pressing roller 101 is also attracted downward. Thereafter, the peeling projection 205 comes into contact with the bearing support frame 201, the suction members 203 and 206 are peeled off, and the upward biasing force by the biasing spring 204 works in a direction opposite to the biasing force. When it becomes larger than the magnetic attraction force between 203 and 206, the attraction state between the attraction members 203 and 206 is released. The bearing 202 is again urged upward by the urging spring 204. Thus, the holding mechanism 200 can shift from the state shown in FIG. 6C to the state shown in FIG.

  According to the present invention, when the holding mechanism holding the medium pressing unit moves with the lifting / lowering operation of the transport unit or the image recording unit, the slidable biasing mechanism and the magnetic adsorption member act to move the head. The position of the medium pressing portion with respect to the nozzle surface of the portion can be made variable. Accordingly, at least during the image recording operation, the medium pressing portion protrudes below the nozzle surface of the ink head to prevent the recording medium from coming into contact with the ink head, and at least during the cleaning operation, the medium pressing portion serves as the nozzle of the ink head. It can evacuate without projecting downward from the surface so that the cleaning operation is not hindered.

(Modifications 1 and 2)
In the first and second modified examples, when the transport unit 13 is moved to the recording position by the lifting mechanism 14, the transport unit suction member (magnet) 203 and the bearing suction member (magnet) 206 of the holding mechanism 200 are reliably suctioned. A repulsive force / attractive force generating mechanism for assisting adsorption by generating an auxiliary magnetic field is provided so as to match.

  Specifically, in Modification 1 shown in FIGS. 8A to 8C, when the transport unit 13 is raised by the elevating mechanism 14 to the recording position, the holding mechanism 200 can be slidably attached. A repulsive force generating mechanism 300 that generates a repulsive force is provided so that the urging mechanism moves downward. Moreover, in the modification 2 shown by FIG. 9 (a) thru | or (c), the attractive force generation mechanism 310 which generate | occur | produces an attractive force is provided.

  As shown in FIGS. 8A to 8C, the repulsive force generation mechanism 300 of Modification 1 includes a protruding member 301, a repulsive force generation unit 302 that is a magnetic circuit, and a magnet 303. One end side of the protruding member 301 is attached to the platen 42 of the conveying unit 13, and the other end side extends upward to the vicinity of the repulsive force generating unit 302 disposed in the image recording unit 12. The repulsive force generation unit 302 is provided in the image recording unit 12 so as to face the protruding member 301. The magnet 303 is provided on the upper surface of the bearing 202 so as to face the repulsive force generator 302.

  As shown in FIGS. 9A to 9C, the attractive force generating mechanism 310 of the second modified example is similar to the first modified example in that the protruding member 311, the attractive force generating unit 312 that is a magnetic circuit, the magnet 313, have. However, unlike the first modification, the protruding member 311 is provided in the image recording unit 12, and the attractive force generating unit 312 is provided in the conveying unit 13. Further, the bearing suction member 206 is disposed on the other end side of the spring 314 attached to the platen 42 at one end side so as to face the transport unit suction member 203. The magnet 313 is provided on the lower surface of the bearing attracting member 206 so as to face the attractive force generating unit 312.

  In the first modification, when the conveying unit 13 is lifted by the lifting mechanism 14 and the protruding member 301 comes into contact with the repulsive force generating unit 302 as shown in FIG. 8B, the repulsive force generating unit 302 is provided in the bearing 202. A magnetic field for repelling the magnet 303 is generated or strengthened. For this reason, when the conveyance unit 13 is raised to the recording position, the bearing 202 to which the conveyance unit suction member 203 is attached and the medium pressing roller 101 held by the bearing 202 also move downward integrally, and the conveyance unit The distance between the adsorption member 203 and the bearing adsorption member 206 is narrowed. And the magnetic attraction force between these adsorption members 203 and 206 increases, and it can be made into an adsorption state reliably.

  In the second modification, the bearing 13 is lifted by the elevating mechanism 14 while the bearing suction member 206 disposed in the transport unit 13 is constantly biased upward by the spring 314, and the transport unit suction member 203. The bearing adsorbing member 206 is in an adsorbing state. Then, as shown in FIG. 9B, as in the first modification, when the protruding member 311 comes into contact with the attractive force generating unit 312, the attractive force generating unit 312 remains on the bearing adsorbing member 206 while being in the adsorbed state with the bearing 202. A magnetic field for attracting the provided magnet 313 downward is generated or strengthened. For this reason, when the transport unit 13 is raised to the recording position, the transport unit suction member 203 and the bearing suction member 206 are integrally moved downward to lower the medium pressing roller 101 to a desired position. it can.

FIGS. 10A to 10C are diagrams conceptually showing one form of the magnetic circuit 500 such as the repulsive force generator 302 / attractive force generator 312 of the first and second modifications.
The magnetic circuit 500 includes a magnet 501 that is rotatable about a rotation axis, a shaft 502 that is provided integrally with the magnet 501, abuts against the protruding member 301/311, and the shaft 502 is connected to the protruding member 301/311 side. And a pair of magnetic metals 503 surrounding the magnet 501.

  As shown in FIG. 10A, in a state where the protruding member 301/311 is not in contact with the shaft 502, the shaft 502 is urged toward the protruding member 301/311 by an urging means (not shown), and the magnet 501 is magnet 303. / 313 is positioned in the vertical direction. In this state, the magnetic field of the magnet 501 has no effect (less) on the magnetic field of the magnet 303/313, and there is no repulsive / attractive force on the magnet 303/313 by the magnetic circuit 500 (less).

  From this state, when the protruding member 301/311 abuts on the shaft 502 and presses the shaft 502, the magnet 501 rotates. And the magnet 501 will be in the state located in parallel with respect to the magnet 303/313, as shown in FIG.10 (b). In this state, the magnetic field of the magnet 501 generates a magnetic force on the magnet 303/313 via the magnetic metal 503. At this time, when the magnetic circuit 500 is the repulsive force generator 302, as shown in FIG. 10B, the N pole of the magnet 303 and the N pole of the magnet 501, and the S pole of the magnet 303 and the S pole of the magnet 501. Are opposed to each other, and the magnetic circuit 500 generates a repulsive force on the magnet 303 provided on the bearing 202. When the magnetic circuit 500 is the attractive force generator 312, the N pole of the magnet 313 and the S pole of the magnet 501, and the S pole of the magnet 313 and the N pole of the magnet 501, as shown in FIG. The magnetic circuits 500 oppose each other and generate an attractive force with respect to the magnet 313 provided on the bearing attracting member 206.

FIGS. 11A to 11D are diagrams conceptually showing other forms of the magnetic circuit 510 such as the repulsive force generator 302 / attractive force generator 312 of the first and second modifications.
The magnetic circuit 510 includes a magnet 511 provided rotatably around a rotation axis, a shaft 512 provided integrally with the magnet 511 and in contact with the protruding member 301/311, and the magnet 511 as shown in FIGS. (D) biasing means (not shown) for biasing counterclockwise (one direction of rotation). Further, at the end on the repulsive force generating portion 302 / attractive force generating portion 312 side of the projecting members 301/311 of the first and second modifications, for example, as shown in FIG. An extended slit 514 is cut.

  As shown in FIG. 11A, in a state where the projecting member 301/311 is not in contact with the shaft 512, the magnet 511 is urged in one direction of rotation by an urging means (not shown), and the magnet 511 is magnet 303/313. It will be a position not facing. In this state, the magnetic field of the magnet 511 has no effect (less) on the magnetic field of the magnet 303/313, and there is no repulsive / attracting force on the magnet 303/313 by the magnetic circuit 510 (less).

  When the protruding member 301/311 moves from this state, the shaft 512 fits into the slit 514, and the shaft 512 moves along the slit 514 as shown in FIG. And the magnet 511 is opposed to the magnet 303/313 as shown in FIG. 11 (c) or 11 (d). At this time, when the magnetic circuit 510 is the repulsive force generator 302, the same polarity of the magnet 303 and the magnet 511 are opposed to each other as shown in FIG. 11C, and the magnetic circuit 510 is a magnet provided on the bearing 202. Repulsive force is generated for 303. When the magnetic circuit 510 is the attractive force generator 312, the magnets 313 and 511 are opposite to each other as shown in FIG. 11D, and the magnetic circuit 510 is provided on the bearing attracting member 206. An attractive force is generated with respect to the magnet 313.

  As described above, in the first and second modifications, the assisting force is generated so that the repulsive force generated from the repulsive force generating mechanism 300 or the attractive force generated from the attractive force generating mechanism 310 is reliably attracted to each other. Can work as.

Note that these mechanisms 300 and 310 are merely examples, and the present invention is not limited thereto, and the effect of the present invention can be obtained as long as the magnetic circuit is turned on and off in association with the lifting operation.
The same effect can be obtained not only by the magnetic circuit but also by a mechanism that controls the electromagnet.

(Modification 3)
In the third modification example, all the members facing the head portion 31 escape from the head portion 31.

  FIG. 12A is a side view of the head unit 31 and the platen 42 according to the third modification, and FIG. 12B is a top view of the head unit 31 and the platen 42. In the present modification, the platen 42 and other members of the transport unit 13 that are opposed to the head unit 31 do not interfere with the head unit 31 when close to the head unit 31. An opening is formed in the. Thereby, when the conveyance part 13 is raised by the raising / lowering mechanism 14, the conveyance part 13 moves upwards rather than usual. That is, the members including the platen 42 of the transport unit 13 can move upward from the recording position.

Therefore, in this modification, a roller pickup operation as shown in FIGS. 13A and 13B can be performed before the operation of moving the transport unit 13 to the recording position.
Note that this modification is not applicable to an ink jet printer having a belt conveyance type conveyance section, and is not applicable to a conveyance section having an endless belt over the entire surface. Only applicable.

(Modification 4)
In the fourth modification, the frequency of the motor is tuned with the natural frequency of the medium pressing roller.
In this modification, as shown in FIG. 14, in order to reliably retract the medium pressing roller 101 above the nozzle surface 35 a of the ink head 35, the conveying unit attracting member (magnet) 203 is applied in the state where no external force is applied. Assume that the bearing attracting member (magnet) 206 and the bearing attracting member 206 are separated from each other so that they cannot be attracted to each other.

  In this modified example, the mass system (medium pressing roller 101, medium pressing roller 101, and the pressing force holding mechanism 200 holding the medium and the natural frequency obtained from the rigidity of the biasing spring 204 are vibrated. The bearing 202 and the conveyance unit adsorption member 203) are brought into a resonance state. This vibration is performed by driving the motor 51 (or the drive system motor 320) of the transport unit 13, for example. In general, the inkjet printer 1 is provided with a plurality of drive systems, but the same effect can be obtained regardless of which drive system in the printer 1 is used. Alternatively, a drive system for vibration may be newly provided.

  At the time of recording, the motor 51 (or the motor 320 of the drive system) of the transport unit 13 is driven at a rotation number calculated in advance, and the inkjet printer 1 is vibrated at a specific frequency. The mass system (the medium pressing roller 101, the bearing 202, and the conveyance unit suction member 203) that is vibrated at the natural frequency resonates. Since the amplitude increases in the resonance state, a state occurs in which the distance between the adsorption members 203 and 206 is short. The attracting force increases as the distance between the attracting members 203 and 206 becomes shorter, and becomes the largest when contacting. Therefore, if vibration is continued, the distance between the adsorbing members 203 and 206 gradually decreases and adsorbs to each other. The retreat distance and the magnetic force may be set in consideration of the distance and the attractive force at this time.

In this case, it is better if there is a detection mechanism for detecting the completion of suction between the transport unit suction member 203 and the bearing suction member 206. As the detection mechanism, for example, a mechanism that connects a terminal to the contact point of the adsorption members 203 and 206 and energizes when the contact is made can be employed.
Further, at this time, the variation can be absorbed if the rotation speed band of the drive system is changed to the adsorption state in consideration of the variation in rigidity and mass.

  In any of the embodiments of the present invention and Modifications 1 to 4, for example, as shown in FIGS. 15A and 15B, the press holding mechanism 200 allows the medium press roller 101 to move up and down. The upper and lower sides of the medium pressing roller 101 may be supported by a spring so that the medium pressing roller 101 has a degree of freedom in the vertical direction. If the medium pressing roller 101 has a degree of freedom in the vertical direction and is urged with a constant pressing force, the rotating state of the medium pressing roller 101 continues and the transport performance of the transport belt 41 is improved. be able to. Therefore, if such a configuration is added to the embodiment of the present invention and each modification, it is possible to expect an improvement in conveyance performance.

  In addition, for example, as shown in FIG. 16, if the shape of the contact surface between the transport unit suction member 203 and the bearing suction member 206 is tapered, the suction position accuracy when the suction members 203 and 206 are sucked to each other is improved. As a result, the orthogonality of the medium pressing roller 101 with respect to the transport direction can be maintained with high accuracy.

As mentioned above, although embodiment and the modification of this invention were demonstrated, this invention is not limited to these, A various change is possible in the range which does not deviate from the summary of this invention.
Further, the above-described embodiments and modifications include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the problem to be solved by the invention can be solved, and is described in the column of the effect of the invention. When an effect is obtained, a configuration from which the configuration requirements are deleted can be extracted as an invention.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Recording medium, 11 ... Medium supply part, 12 ... Image recording part, 13 ... Conveyance part, 14 ... Elevating mechanism, 15 ... Medium storage part, 16 ... Control part, 21 ... Supply stand, 22 ... Supply roller 23 ... Registration roller pair 31 ... Head portion 32 ... Head holding member 33 ... Spacing adjusting member 34 ... Opening 35 ... Ink head 35a ... Nozzle surface 41 ... Conveying belt 42 ... Platen 43 DESCRIPTION OF SYMBOLS ... Suction fan, 44 ... Drive roller, 45 ... Drive roller, 46 ... Tension roller, 47 ... Conveyance frame, 51 ... Motor, 52 ... Wire, 53 ... Winding part, 54 ... Winding shaft, 55 ... Pulley, 56 ... Torque limiter, 61 ... discharge roller pair, 62 ... stocker, 101 ... medium press roller, 200 ... press holding mechanism, 201 ... bearing support frame, 202 ... bearing, DESCRIPTION OF SYMBOLS 03 ... Conveying part adsorption | suction member, 204 ... Energizing spring, 205 ... Stripping protrusion, 206 ... Bearing adsorption member, 300 ... Repulsive force generation mechanism, 301 ... Protrusion member, 302 ... Repulsive force generation part, 303 ... Magnet, 304 ... Shaft, 310: attractive force generating mechanism, 311 ... projecting member, 312 ... attractive force generating portion, 313 ... magnet, 314 ... spring, 320 ... motor.

Claims (4)

A head portion having a nozzle surface on which a plurality of nozzles are formed;
A head holding part holding the head part;
A platen portion that is disposed to face the nozzle surface and conveys a recording medium;
A platen holding part for holding the platen;
In order to change a head gap, which is an interval between the nozzle surface and the platen portion, to at least a head gap at the time of recording and a head gap at the time of retraction larger than the head gap at the time of recording, A moving mechanism for moving at least one of the platen holding part;
A medium pressing part for pressing the recording medium conveyed to the platen part;
In an inkjet printer comprising:
An urging portion provided in the head holding portion;
An abutting member attached to the urging unit is provided, and a pressing gap that is an interval between the medium pressing unit and the platen is set to a pressing gap that is smaller than a head gap at the time of recording and at the time of the retraction. A medium press holding part that holds the medium press part so as to be movable to a holding gap at the time of retraction larger than the head gap;
A support frame portion provided in the head holding portion and supporting the medium press holding portion;
A first adsorbing member attached to the medium holding unit;
A second adsorbing member provided in the platen holding part facing the first adsorbing member;
Further comprising a holding mechanism having
When the moving mechanism moves at least one of the head holding part and the platen holding part so that the head gap is the head gap at the time of recording, the first and second attracting members are magnetically connected to each other. The medium pressing part protrudes closer to the platen part than the nozzle surface by being adsorbed and brought into an adsorbed state by contact,
When the moving mechanism moves at least one of the head holding part and the platen holding part so that the head gap is the head gap at the time of retraction, the abutting member comes into contact with the support frame part, In addition, the urging force by the urging portion works in the opposite direction to the magnetic attraction force between the first and second attraction members, and becomes larger than the magnetic attraction force, so that the first and second An ink jet printer, wherein the suction state of the suction member is released, and the medium pressing portion is retracted closer to the head portion than the nozzle surface.   The ink jet printer according to claim 1, wherein one of the first and second attracting members is a permanent magnet and the other is a magnetic metal, or both are permanent magnets.   Assisting the holding mechanism to ensure that the first and second adsorbing members are in the adsorbing state and to ensure that the first and second adsorbing members are released from the adsorbing state. The inkjet printer according to claim 1, further comprising a mechanism that generates at least one of repulsive force and attractive force that generates a magnetic field.   The pressing and holding mechanism is added so as to ensure that the first and second suction members are in the suction state and that the first and second suction members are reliably released from the suction state. The inkjet printer according to claim 1, further comprising a drive unit that vibrates.

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