JP5205534B2 - Ink jet recording head capping structure and ink jet recording apparatus - Google Patents

Description

  The present invention relates to an ink jet recording head capping structure and an ink jet recording apparatus.

  As shown in FIG. 20, for example, a recording head provided in a normal ink jet recording apparatus has a face surface 101 at the tip, and a nozzle 102 for ejecting ink droplets is formed on the face surface 105. The head portion 103 protrudes (Patent Document 1).

Further, the recording apparatus is provided with a dish-shaped rubber cap 109 to prevent the ink in the nozzle 102 from drying. The cap 109 covers the head portion 103. That is, the cap 109 is provided with a raised portion 110 that elastically contacts the outer peripheral region 106 of the face surface 101, and a suction hole 111 for sucking ink remaining in the nozzle 102 is formed at the bottom. .
Further, before the cap 109 is covered, the remaining ink on the nozzle surface 105 of the head portion 103 is wiped with a wiping blade (not shown).

JP 2006-103275 A

In the conventional recording apparatus, when ink is filled into the nozzle 102 of the head unit 103 during printing, the ink flows out of the nozzle 102 and wets the nozzle surface 175, but part of the ink also spreads to the side surface 112 of the head unit 103. In addition, as described above, the remaining ink on the nozzle surface 175 of the head unit 103 is wiped off by the wiping blade, but a part of the remaining ink is driven to the side surface 112 of the head unit 103. Further, when the ink adhering to the side surface becomes droplets, it spreads to the outer peripheral region.
Here, in the conventional recording apparatus, since the distance between the side surface of the head portion 103 and the position where the raised portion 110 of the cap 109 contacts is only 1 mm or less, the cap 109 is attached to the side surface 112 of the head portion or the outer peripheral region 106. A part of the ink protrudes outside the raised portion 110. The ink that protrudes to the outside of the raised portion 110 is exposed to the outside air, so it dries, and the viscosity becomes high and the ink solidifies at worst.
Therefore, when the head unit 103 is cleaned with the wiping blade, if the wiping blade ink is solidified, the wiping blade is deformed or damaged when the wiping blade comes into contact with the solidified ink. A wiping failure occurs and the ink remains unwiped, which causes a problem in ink ejection. Further, when the wiping blade comes into contact with the thickened ink and the thickened ink adheres to the wiping blade, the thickened ink may adhere to the nozzle 102 and obstruct ink ejection.

  Therefore, the present invention solves the above-described problems in the conventional ink jet recording apparatus, suppresses the ink adhering to the side surface of the head from thickening, suppresses the remaining ink from adhering to the nozzle surface, and It is a technical problem to provide a capping structure of an ink jet recording head that does not cause ejection failure even when left for a period of time and can prevent image disturbance, and an ink jet recording apparatus using the same.

（但し、Ｓはヘッド部側面に付着したインク液滴の断面積［ｍ²］を示し、γはインク滴の表面張力［ｍＮ／ｍ］、θはヘッド部の側面と液滴の上面とのなす角度［度］、ρは液滴の密度［ｋｇ／ｍ²］、ｇは重力加速度［ｍ／ｓ²］である。）
また、前記キャップの枠部先端に弾性体からなる突条が設けられており、該突条と対向する前記記録ヘッド部の先端表面には、前記突条が嵌合する環状溝が形成されており、前記記録ヘッド部に、前記環状溝から前記突条を押し出すための押し出し機構が設けられているのが好ましい。その場合、前記押し出し機構は、前記記録ヘッドに回転自在に設けられた軸と、この軸に固定された板状ないし扁平ローラ状の押し出し部材とからなり、前記軸を回転させて、前記押し出し部材によって前記突条を環状溝から押し出すようにするのが好ましい。 The capping structure of the ink jet recording head according to the present invention includes a recording head portion in which the head portion protrudes downward and a nozzle for discharging ink droplets is formed on the tip nozzle surface of the head portion, a bottom surface portion, and a periphery of the bottom surface portion. And a cap that covers the head portion at the time of non-recording, and with the cap covered on the head portion, between the side surface of the head portion and the inner surface of the frame portion of the cap, A gap larger than the maximum thickness H of the ink droplets adhering to the side surface of the head portion represented by Formula 1 is provided (Claim 1).

(Where S represents the cross-sectional area [m ² ] of the ink droplet attached to the side surface of the head portion, γ represents the surface tension of the ink droplet [mN / m], and θ represents the distance between the side surface of the head portion and the top surface of the droplet. (The angle formed is [degree], ρ is the density of the droplet [kg / m ² ], and g is the acceleration of gravity [m / s ² ].)
Further, a protrusion made of an elastic body is provided at the tip of the frame portion of the cap, and an annular groove into which the protrusion is fitted is formed on the tip surface of the recording head portion facing the protrusion. Preferably, the recording head portion is provided with an extrusion mechanism for extruding the protrusion from the annular groove. In this case, the push-out mechanism includes a shaft rotatably provided on the recording head and a plate-like or flat roller-like push-out member fixed to the shaft, and the push-out member is rotated by rotating the shaft. The protrusion is preferably pushed out of the annular groove.

The gap formed between the side surface of the head portion and the inner surface of the cap frame portion may be 2 mm or more .

  An ink jet recording apparatus of the present invention is provided with the above-described capping structure of an ink jet recording head, and is provided on a transport unit for transporting recording paper, and the head portion is provided below. An ink jet recording head part that protrudes and has a nozzle that discharges ink droplets formed on the nozzle surface at the tip of the head part, and a bottom part and a frame part that rises from the periphery of the bottom part. Ink droplets adhering to the side surface of the head unit represented by Formula 1 between the side surface of the head unit and the inner surface of the frame part of the cap in the state where the cap is put on the head unit A gap larger than the maximum thickness H is provided.

According to the capping structure of the present invention, when the nozzle surface is covered with the cap, the ink droplets attached to the side surface of the head portion expressed by the formula 1 between the side surface of the head portion and the inner surface of the frame portion of the cap. Since a gap larger than the maximum thickness H (preferably a gap of 2 mm or more) is provided, it is possible to prevent the ink existing on the side surface of the head portion from protruding outside the cap and coming into contact with the outside air and drying and solidifying. it can. As a result, when the head portion is wiped with the wiping blade, the solidified ink causes the wiping blade to be deformed or damaged, so that sufficient wiping cannot be performed, so that ink remains on the nozzle surface and affects ink ejection. Can be prevented.
In addition, if the thickened ink that adheres to the side surface of the nozzle portion adheres to the tip of the blade, the thickened ink adheres to the nozzle when the nozzle surface is cleaned, and the nozzle hole is blocked. The ink attached to the side surface of the nozzle portion and thickened does not move to the frame portion of the cap, so that the nozzle is not blocked, thereby preventing non-ejection even when left for a long period of time and eliminating image disturbance.

  In such a capping structure, the frame portion of the cap is formed of a rigid material, and an annular ridge made of an elastic body is provided at the tip of the frame portion, and the tip surface of the recording head portion facing the ridge In the case where the annular groove into which the protrusion is fitted is formed, the inside of the cap over the head portion can be kept airtight, and the ink droplet can be prevented from drying.

  When the recording head is provided with an extrusion mechanism for extruding the ridge from the bottom of the annular groove, the ridge is smoothly annulared even after the protrusion is fitted into the annular groove for a long time. Can be extracted from the groove.

1 is a cross-sectional view of a main part showing an embodiment of a capping structure of an ink jet recording head according to the present invention. It is a top view of the cap of FIG. It is the A section expanded sectional view of FIG. It is explanatory drawing which shows the droplet of the ink droplet adhering to the side surface of a head part. 1 is a schematic plan view showing an example of an ink jet recording apparatus to which the present invention is applied. It is a typical front view which shows the outline | summary of an inkjet recording device, and shows the state at the time of recording. It is a typical front view which shows the outline | summary of an inkjet recording device, and shows the state which covered the cap on the nozzle. It is a right view which shows a cap unit. It is an external appearance perspective view which shows a horizontal drive mechanism. It is a disassembled perspective view explaining the attachment state of a cap unit. It is a perspective view which shows the state which abbreviate | omitted the cap unit from the horizontal drive mechanism. It is explanatory drawing (plan view) of the drive content of a horizontal drive mechanism. (A) is a right view which shows the drive mechanism of a wiper member, (b) is a front view which shows the drive mechanism of a wiper member. (A) is a right side view showing the cleaning state of the row having the first recording head and the third recording head, and (b) is a right side view showing the cleaning state of the row having the second recording head. It is a typical top view which shows the outline | summary of the inkjet recording device which concerns on 2nd Embodiment of this invention. It is a right view which shows the cleaning state of the inkjet recording device which concerns on 2nd Embodiment of this invention. It is a perspective view which shows the raising / lowering apparatus of a conveyance unit. It is a perspective view of the eccentric cam of the raising / lowering apparatus shown in FIG. It is a partial enlarged front view which shows the raising / lowering apparatus of FIG. 17, and its periphery. It is sectional drawing which shows an example of the capping structure of the conventional recording device.

  Next, a capping structure of the present invention and an ink jet recording apparatus using the same will be described with reference to the drawings. 1 is a schematic cross-sectional view of a main part showing an embodiment of the recording apparatus of the present invention, FIG. 2 is a plan view of the cap of FIG. 1, FIG. 3 is an enlarged view of a Y part of FIG. It is explanatory drawing which shows the droplet of the ink droplet which adhered.

  FIG. 1 shows a capping structure 12 according to this embodiment. In the capping structure 12, an ink jet recording head section (hereinafter also referred to as a recording head section) 10 includes a substantially rectangular parallelepiped recording head 13 and a head section 14 fixed by the recording head 13. . The head portion 14 has a substantially rectangular parallelepiped shape and protrudes from the front end surface 15 of the recording head 13 by about 1 to 10 mm. The planar shape of the head portion 14 is substantially rectangular. A number of nozzles 16 are formed in the head portion 14. The tip of the head portion 14 is a flat nozzle surface 17, and the nozzle 16 is open at the center thereof. The side surface 18 of the head portion 14 is substantially perpendicular to the nozzle surface 17.

  The cap 11 for capping the head portion 14 includes a bottom surface portion 21 and a frame portion 22 (side wall) that rises perpendicularly from the periphery of the bottom surface portion. As shown in FIG. 2, the frame portion 22 has a substantially rectangular shape in plan view. As shown in FIGS. 2 and 3, an annular ridge 24 made of an elastic body such as rubber protrudes from the opening end surface 23 which is the upper end of the frame portion 22. A column 25 having rigidity is built in the ridge 24. The column 25 has a shape with rounded upper corners so as not to damage the elastic body. The pillar 25 and the frame portion 22 can be made of the same or different metals or synthetic resins (such as thermosetting resins).

  When the recording apparatus is not used for a long time (non-recording), the cap 11 is raised by an elevating apparatus using an eccentric cam (not shown) to cap the lower end surface of the head section 14 of the recording head section 10. Then, the ridge 24 at the upper end of the frame portion 22 is fitted into the front end surface 15 of the recording head 13 in an airtight manner. This prevents ink droplets from drying.

At that time, a gap 28 having a size that does not contact the droplets of the ink droplets attached to the side surface 18 is formed between the side surface 18 and the inner surface 27 of the frame portion 22 of the cap 11 on the entire circumference of the head portion 14. . The dimension of the gap 28 is somewhat larger than the maximum thickness H of the droplet 29 attached to the side surface 18, as shown in FIG. The maximum thickness H of the droplet 29 can be measured, but can also be obtained from the following formulas 1 and 2 as a design value.

Here, S is the cross-sectional area [m ² ] of the droplet 29 in the state shown in FIG. 4. From the balance between gravity (ρgS · L) applied to the droplet and surface tension (γ · cosθ · L), It can be calculated by Equation 2. L is the dimension in the depth direction of the head. The reason why the square root of the cross section S is H is to convert a two-dimensional value into a one-dimensional length dimension.

Where γ is the surface tension [mN / m] of the ink droplet, θ is the angle [degree] between the side surface 18 of the head portion 14 and the top surface of the droplet 33 (contact angle, see θ in FIG. 4), and ρ is the liquid Drop density [kg / m ² ], g is gravitational acceleration [m / s ² ].

For example, a normal ink has a density ρ of 1000 kg / m ² , a gravitational acceleration g of 9.8 m / s ² , and a surface tension γ of 28 to 40 m. Therefore, if the contact angle θ is 5 to 30 degrees, The cross-sectional area S is about 4 mm ² . Therefore, since the maximum thickness H of the droplet 29 is 2 mm, a dimension larger than 2 mm may be adopted as the dimension of the gap 28.

  Further, in the capping structure 12 shown in FIG. 1, an extrusion mechanism 36 for extruding the protrusion 24 fitted in the annular groove 35 is provided inside the recording head 13.

  The push-out mechanism 36 includes a shaft 37 that is rotatably provided on the recording head 13 and a plate-like or flat roller-like push-out member 38 that is fixed to the shaft 37. The shaft 37 and the pushing member 38 are usually made of metal, but may be made of synthetic resin. The shaft 37 is rotated manually or mechanically, and the protrusion 24 at the upper end of the frame portion 22 is pushed out from the annular groove 35 by the pushing member 38.

  The pushing mechanism 36 may have a size larger than the length of the cap 11 on the longitudinal side of the recording head unit 10. In that case, it is a roller type. Otherwise, an extrusion mechanism 36 is provided at the frame end of the cap 11 and the center of each frame. In other words, a columnar member is fixed to the shaft 37 so that a roller member (not shown) having an elliptical cross section extends in a direction perpendicular to the paper surface. This columnar member is normally configured such that the short axis of the ellipse is oriented in the vertical direction and does not contact the tip of the cap 11. When the cap 11 is pushed out, the long axis of the elliptical columnar member faces the vertical direction along with the rotation of the shaft 37 and pushes out the cap. The columnar member 37 may have a length corresponding to the frame end and each frame.

  In the ink jet recording apparatus including the capping structure 12 configured as described above, ink droplets flow out from the nozzles 16 when the recording head unit 10 is pressurized and filled with ink droplets. The ink droplet that has flowed out wets the nozzle surface 17 and spreads to the side surface 18 of the head portion 14. Further, when the nozzle surface 17 is wiped with a wiper member (wiper blade) which will be described later, the ink droplets that have wetted the nozzle surface 17 are driven to the side surface 18 of the head portion at the same time as the wipe, and the side surface 18 is as shown in FIG. A droplet (雫) 29 is formed. The maximum protrusion height H of the droplet 29 formed at this time from the side surface 18 of the head portion is about 2 mm as described above.

  However, in this recording apparatus, as shown in FIG. 1, the gap between the side surface 18 of the head portion and the inner peripheral surface of the frame portion 22 of the cap 11 is equal to or greater than the maximum thickness H of the droplet. Even when the liquid drops, no droplets adhere to the inner surface of the frame portion 22 of the cap. Therefore, when the cap is put on the recording head unit 10 again, the thickened liquid droplet does not adhere to the nozzle surface 17 and the problem of blocking the nozzle 16 is solved.

  Furthermore, in the capping structure 12, an annular ridge 24 made of an elastic body is provided at the tip of the frame portion 22 of the cap 11, and an annular groove 35 that fits the ridge 24 on the tip surface 15 of the recording head portion 10. Is formed, the airtightness inside the cap is increased.

  Further, as shown in FIG. 1, the annular groove 35 formed on the front end surface 15 of the recording head portion is provided with an extruding mechanism 36 for pushing out the protrusion 24 from the annular groove. Even when the is operated, there is no problem that the ridge 24 is broken when the ridge 24 sticks to the annular groove 35 and the cap 11 is moved up and down.

  Next, the horizontal movement mechanism of the cap 11 for capping in this embodiment will be described. FIG. 5 is a schematic plan view showing an example of an ink jet recording apparatus to which the present invention is applied. 6 and 7 are schematic front views showing an outline of the ink jet recording apparatus. FIG. 6 shows a state at the time of recording, and FIG. 7 shows a state in which the nozzle is covered with a cap.

  The ink jet recording apparatus 1 includes a transport unit 2 that transports recording paper, a recording head unit 10 provided on the transport unit 2, a cap position A below the recording head unit 10, and a lower part of the recording head unit 10. A cap unit 4 that moves horizontally with respect to the standby position B off the side and moves up and down at the cap position A.

  The transport unit 2 includes a driving roller 20, a driven roller 21, a circulating transport belt 22 that wraps around the drive roller 20, a tension roller 23 that adjusts the tension of the transport belt 22, and a lower portion of the upper surface portion of the transport belt 22. And a suction unit 24 provided. The conveying belt 22 is provided with a number of through holes for suction (not shown), and at the time of recording, the recording paper can be adsorbed and conveyed to the conveying belt 22 through the through holes. Further, at the time of recording, an image is formed by ejecting ink from an ink ejection nozzle of the recording head unit 10 to be described later on the recording paper that is adsorbed and conveyed by the conveying belt 22. The transport unit 2 configured as described above is moved up and down by lifting means described later.

  The recording head unit 10 has a plurality of, for example, twelve recording heads 13 fixed at predetermined positions and having a plurality of ink ejection nozzles 16 (ejection ports) formed on the lower nozzle surface 17. The recording heads 13 are arranged in a plurality of rows, for example, eight rows, and two rows are arranged in four rows with a gap in the row direction. A pair of recording heads 13 is composed of two rows and one adjacent row. Here, the recording heads on the standby position B side of the two rows of recording heads 13 are the first recording head 13a, The recording head on the opposite side is the third recording head 13c, and the recording head 13 in the next row is the second recording head 13b.

  The above-described twelve recording heads 13 have the same configuration, and there are no nozzles at the peripheral edge C of the nozzle surface 17, and nozzles are disposed at the center D of the nozzle surface 17 (see FIG. 14). Ink is supplied to each nozzle.

  As shown in FIG. 8, the cap unit 4 includes a cap 11 and a wiper means 41 on the upper side. The cap unit 4 is moved horizontally between the cap position A and the standby position B by a horizontal drive mechanism 42 shown in FIGS. 9 to 12, and is moved up and down by a vertical drive mechanism (not shown). In addition, as a vertical drive mechanism, the mechanism etc. which drive the cam etc. which were distribute | arranged to four corners synchronously are used, for example.

  9 is an external perspective view showing the horizontal drive mechanism 42, FIG. 10 is an exploded perspective view for explaining the mounting state of the cap unit 4, and FIG. 11 is a perspective view showing a state in which the cap unit 4 is omitted from the horizontal drive mechanism 42. 12 is an explanatory view (plan view) of the drive content of the horizontal drive mechanism 42.

  The horizontal drive mechanism 42 has two horizontal rail members 43a and 43b spaced apart in the horizontal direction and a direction E in which the cap unit 4 is moved horizontally, and a pair of rail members 43a and 43b extending in the direction E. Is supported horizontally and at a predetermined height via a plurality of support columns 43c. A drive motor 46 is disposed on the rear side of the right rail member 43 a, and a gear 46 a is attached to the rotation shaft of the drive motor 46. A gear 44b-1 provided on the lower side of the rotating pulley 44b meshes with the gear 46a, and a gear 44e-1 provided on the lower side of the rotating pulley 44e is engaged with the gear 46a via the gear 46b. Meshed. A rotating pulley 44a is provided on the front side of the right rail member 43a, and a belt 45a having both ends connected to the front end and the rear end of the slider 45c is stretched over the rotating pulley 44a and the rotating pulley 44b. (FIG. 10).

  On the other hand, a rotary pulley 44c is provided on the front side of the left rail member 43b, and a rotary pulley 44d is provided on the rear side. A belt 45b having both ends connected to the front end and the rear end of the slider 45d is stretched around the rotary pulleys 44c and 44d. Further, an endless belt 45e is stretched between the rotating pulley 44d and the rotating pulley 44e on the right side thereof, and all the rotating pulleys 44a to 44e described above are arranged with the shaft center in the vertical direction.

  Further, the sliders 45c and 45d are provided with rollers 45c-1 and 45d-1 that facilitate sliding. On the sliders 45c and 45d, end portions 4a on both the left and right sides of the cap unit 4, 4b is attached.

  Since the horizontal drive mechanism 42 is thus configured, for example, when the rotation shaft of the drive motor 46 is rotated in the forward direction (clockwise), the right belt 45a rotates counterclockwise and the slider 45c is moved to the rear side → The slider 45d is slid toward the front side, and the left belt 45b rotates clockwise to slide the slider 45d from the rear side toward the front side. As a result, the cap unit 4 moves from the standby position B to the cap position A. When rotated counterclockwise (counterclockwise), the right belt 45a rotates clockwise to slide the slider 45c from the front side to the rear side, and the left belt 45b rotates counterclockwise. Slide the slider 45d from the front side to the rear side. As a result, the cap unit 4 moves from the cap position A to the standby position B. Therefore, the cap unit 4 reciprocates between the cap position A and the standby position B according to the rotation direction of the rotation shaft of the drive motor 46.

  The number of caps 11 corresponds to the number of recording heads 13 (for example, 12) and has the same arrangement relationship as that of the recording heads 13. Each cap 11 has the same number of upward caps corresponding to each nozzle. Further, the cap unit 4 moves horizontally from the cap position A to the standby position B during recording, and moves upward after moving horizontally from the standby position B to the cap position A when covering the nozzle. It is put on. At the time of recording, the cap unit 4 is lowered and the cap is detached from the nozzle.

  The wiper means 41 provided in the cap unit 4 cleans the nozzle surface 17 disposed on the lower surface of the recording head unit 10 and is provided on the upper surface of the cap unit 4. The wiper means 41 includes as many wiper members 47 as the number of rows in which the recording heads 13 are arranged (see FIG. 5). As shown in FIG. 13, each wiper member 47 includes a rubber wiper 47a and a support portion 47b that supports the wiper 47a, and each support portion 47b is rotatably supported on a horizontal shaft 48. Has been. A gear 48 a is attached to the horizontal shaft 48, and the gear 49 a attached to the rotation shaft of the drive motor 49 is engaged with the gear 48 a, and the rotation angle of the wiper member 47 is adjusted by the rotation of the drive motor 49. Is configured to do. Note that reference numeral 50 in FIG. 13 denotes a stopper, which regulates the swing range of the wiper member 47.

  FIG. 14A shows the cleaning state of the row having the first recording head and the third recording head, and FIG. 14B shows the cleaning state of the row having the second recording head. Note that T1 to T6 in FIG. 14 indicate timing.

  When the recording is finished and the cleaning timing is reached, the cap unit 4 that has been waiting at the standby position B until then is started to move toward the cap position A by the horizontal drive mechanism 42. At this time, the cap unit 4 is lowered by the vertical drive mechanism, and the wiper member 47 is laid down (see T1). The posture in which the cap unit 4 is lowered continues until the cleaning is completed, while the posture in which the wiper member 47 lies is continued until the wiper member 47 reaches the rear edge C of the nozzle surface 17 of the first recording head 13a.

  After that, when the wiper member 47 reaches the rear edge C and enters a little inside, the drive motor 49 is operated for all the wiper members 47 to adjust the rotation angle to the posture where the wiper members 47 are raised (T2). reference). Also at this time, the movement toward the cap position A by the horizontal drive mechanism 42 is continued. The central portion D of the nozzle surface 17 of the first recording head 13a is cleaned by the raised posture of the wiper member 47.

  Thereafter, when reaching the front peripheral edge C of the first recording head 13a (see T3), the drive motor 49 is then operated to place the wiper member 47 in a sleeping position (see T4). This state is continued until the wiper member 47 reaches the rear edge C of the nozzle surface 17 of the third recording head 13c. On the other hand, with respect to the second recording head 13b, the wiper member 47 is kept in the raised posture without being in the sleeping posture.

  Then, after the wiper member 47 reaches the rear edge C of the nozzle face 17 of the third recording head 13c and enters a little inside (see T5), the wiper member 47 rises with respect to the third recording head 13c. return. This posture continues until just before the wiper member 47 reaches the front edge C of the nozzle surface 17 of the third recording head 13c.

  Thereafter, when the wiper member 47 passes the front peripheral edge C of the nozzle surface 17 of the third recording head 13c (see T6), all the wiper members 47 are placed in a sleeping posture. This completes the cleaning.

  Subsequently, when the movement of the cap unit 4 to the cap position A is completed, the cap unit 4 is raised by the vertical drive mechanism. Accordingly, each of the caps 11 faces one of the corresponding recording heads 13, and the cap 11 closes each nozzle 16 of the recording head 13.

  As shown in FIG. 15, a spacer 51 is attached by screws or the like so as to be flush with the nozzle surfaces 17 between the first recording head 13a and the third recording head 13c in the same row. Also good. As a result, as shown in FIG. 16, since there is no unevenness in the area where the wiper member 47 moves, ink does not remain on the periphery of the third recording head 13c, and clogging occurs due to the ink. There is nothing. In addition, it is not necessary to change the height of the wiper member 47 on the recording head 13 side by adjusting the rotation angle of the wiper member 47 or the like.

  In the above description, an example in which two recording heads are provided in one column is given, but the present invention can be similarly applied to a configuration in which three or more recording heads are arranged in one column.

  Next, the lifting device of the transport unit 2 will be described. As described above, in order to cap the ink discharge nozzles of the recording apparatus 1, the transport unit is lowered by the lifting device.

  17 is a perspective view of the transport unit and the lifting device, FIG. 18 is a perspective view of an eccentric cam of the lifting device, and FIG. 19 is a partially enlarged front view showing the lifting device and its periphery. 17 shows a state where the transport unit 2 is lowered by the elevating device 140, and FIG. 19 shows a state where it is raised.

  The transport unit 2 includes support members 150 as shown in FIG. Support members 150 are provided at a total of four locations, two on the front side of the transport unit 2 and two on the back side. Each support member 150 includes a fixed portion 151, a slide portion 152, and a spring 153.

  The fixing portion 151 of the support member 150 includes a pin 151a extending substantially vertically upward on its upper surface, and is fixed to the transport unit 2 with screws. The slide part 152 is attached in a state in which it can be slid in the vertical direction via slide mechanisms 154 provided on the left and right sides of the fixed part 151.

  As shown in FIG. 19, the slide mechanism 154 includes a slit 155 provided in the fixing portion 151 and a guide pin 156 provided in the slide portion 152. The slit 155 receives the guide pin 156 and extends long in the vertical direction. A space in which the slide portion 152 is slidable is provided between the fixed portion 151 where the slit 155 is provided and the transport unit 2.

  A spring 153 is provided between the fixed portion 151 and the slide portion 152. The spring 153 is disposed between the outer bottom surface of the fixed portion 151 and the inner bottom surface of the concave portion of the slide portion 152 positioned below the spring 153, and a strong elastic force acts as the slide portion 152 approaches the fixed portion 151. .

  The transport unit 2 is supported by the lifting device 140 from below the slide portion 152 of the support member 150, as will be described later. When the slide part 152 is pushed up, a strong elastic force acts on the spring 153, and the fixed part 151, that is, the transport unit 2 is raised. When the transport unit 2 is raised, the upper surface of the pin 151a comes into contact with the bottom surface of the recording head unit 10 at the final stage, thereby determining the position of the transport unit 2 with respect to the recording head unit 10. As a result, a minute gap is provided between the bottom surface of the recording head unit 10 and the sheet conveyance surface that is the upper surface of the conveyance belt 22.

  And as shown in FIG. 17, the raising / lowering apparatus 140 is provided under the above conveyance units 2. As shown in FIG. The lifting device 140 includes an eccentric cam 141 and a motor (not shown).

  A total of four eccentric cams 141 are provided at locations corresponding to the four support members 50 provided on the front and back surfaces of the transport unit 2. The eccentric cam 141 comes into contact with the outer bottom surface of the slide portion 152 of the support member 150 from below on the circumferential surface thereof.

  Further, as shown in FIGS. 18 and 19, the eccentric cam 141 includes a shaft portion 142 extending in the paper width direction, and is configured by a cam in which the rotation axis is unevenly distributed. The eccentric cam 41 is rotated by a motor around the axis of the shaft portion 142. And the eccentric cam 141 is provided with the bearing 143 which is a some rotation member in the form which one part protrudes outside from the surrounding surface in the peripheral part. The bearing 143 is rotatable about an axis parallel to the rotation axis of the eccentric cam 41. The plurality of bearings 143 come into contact with the bottom surface of the support member 150 of the transport unit 2.

  As shown in FIGS. 18 and 19, the plurality of bearings 143 are arranged in order so as to gradually move away from the rotation axis at the center of the shaft portion 142. That is, at the tip of the eccentric cam 141, the first bearing 143a is located farthest from the rotational axis of the shaft 142, the second bearing 143b is located further closer to the rotational axis, and the third bearing is sequentially described below. 143c and a fourth bearing 143d are disposed, and a fifth bearing 143e is disposed at a position closest to the rotational axis of the eccentric cam 141.

  Then, the raising / lowering operation | movement of the conveyance unit 2 using the eccentric cam 141 of the raising / lowering apparatus 140 is demonstrated. FIG. 19 shows a state in which the transport unit 2 is raised to the highest position (position where the upper surface of the pin 151a of the support member 150 of the transport unit 2 is in contact with the bottom surface of the recording head unit 10) by the lifting device 140. .

  In the normal printing state, as shown in FIG. 19, the printer 1 drives the lifting device 140 to rotate the eccentric cam 141 and move the transport unit 2 to the highest portion. In this state, as described above, a gap suitable for printing is provided between the recording head unit 10 and the transport unit 2. In the eccentric cam 141, the first bearing 143 a disposed at the position farthest from the rotation axis at the center of the shaft portion 142 is in contact with the outer bottom surface of the slide portion 152 of the support member 150 included in the transport unit 2 from below. Yes.

  In order to prevent the ink discharge nozzles of the recording head unit 10 from being dried and clogged, the nozzles are capped and the jamming process generated on the conveyor belt 22 is performed. Descent. At this time, the elevating device 140 drives the motor to rotate the eccentric cam 141. When the transport unit 2 is lowered, the eccentric cam 141 located upstream of the transport unit 30 in the paper transport direction rotates counterclockwise when viewed from the front, and the eccentric cam 141 positioned downstream is rotated clockwise (FIG. 17). And FIG. 19).

  When the eccentric cam 41 is rotated clockwise to lower the transport unit 2 from the state shown in FIG. 194, the second bearing 43b disposed at a location closer to the rotation axis than the first bearing 43a is followed by the first bearing 43a. Comes into contact with the outer bottom surface of the slide portion 52, that is, the bottom surface of the transport unit 2. In this way, the two adjacent bearings 43 have a period of contact with the bottom surface of the transport unit 2 at the same time.

  When the rotation of the eccentric cam 41 further proceeds, the second bearing 43b alone contacts the bottom surface of the transport unit 2 and supports the transport unit 2.

  As the eccentric cam 41 continues to rotate, the third bearing 43c and then the fourth bearing 43d abut against the bottom surface of the transport unit 2 and support the transport unit 2. As in the case of the first and second bearings, the third bearing 143c and the fourth bearing 143d also have a period in which two adjacent bearings 143 are in contact with the bottom surface of the transport unit 2 at the same time. Yes.

  Then, at the final stage of the lowering of the transport unit 2, the fifth bearing 143 e disposed at a location closest to the rotation axis of the eccentric cam 141 abuts on the bottom surface of the transport unit 2 alone to support the transport unit 2. Thereby, a relatively wide working space is provided between the recording head unit 10 and the transport unit 2.

  Thereafter, to return the transport unit 2 to the normal printing position, the transport unit 2 can be raised to the state shown in FIG. 4 by rotating the eccentric cam 141 counterclockwise.

  In this way, it is possible to gradually and smoothly change the magnitude of the load applied to the driving device such as the motor for rotating the center cam 141 itself, its shaft 142, and eccentric cam 141.

DESCRIPTION OF SYMBOLS 10 Recording head part 11 Cap 12 Capping structure 13 Recording head 14 Head part 15 Front end surface 16 Nozzle 17 Nozzle surface 22 Frame part 23 Front end surface 24 Projection 25 Pillar 28 Crevice 29 Droplet H Maximum droplet thickness 35 Annular groove 36 Extrusion mechanism

Claims (4)

A recording head part in which a head part projects downward and a nozzle for ejecting ink droplets is formed on the tip nozzle surface of the head part;
A bottom portion and a frame portion that rises from the periphery of the bottom portion; and a cap that covers the head portion when not recording,
A gap larger than the maximum thickness H of the ink droplets attached to the side surface of the head portion expressed by the following formula 1 between the side surface of the head portion and the inner surface of the frame portion of the cap in a state where the cap is put on the head portion. Provided ,
A protrusion made of an elastic body is provided at the front end of the frame portion of the cap, and an annular groove into which the protrusion is fitted is formed on the front end surface of the recording head portion facing the protrusion. The recording head unit is provided with an extrusion mechanism for extruding the protrusion from the annular groove,
The extrusion mechanism includes a shaft rotatably provided on the recording head and a plate-like or flat roller-like extrusion member fixed to the shaft, and the projection is rotated by the extrusion member. A capping structure for an ink jet recording head, wherein a strip is pushed out from an annular groove .

(Where S represents the cross-sectional area [m ² ] of the ink droplet attached to the side surface of the head portion, γ represents the surface tension of the ink droplet [mN / m], and θ represents the distance between the side surface of the head portion and the top surface of the droplet. (The angle formed is [degree], ρ is the density of the droplet [kg / m ² ], and g is the acceleration of gravity [m / s ² ].)   The capping structure according to claim 1, wherein the gap formed between the side surface of the head portion and the inner surface of the frame portion of the cap is 2 mm or more. A transport unit for transporting recording paper;
An ink jet recording head portion provided on the transport unit, the head portion protruding downward, and a nozzle for discharging ink droplets formed on a tip nozzle surface of the head portion;
A bottom portion and a frame portion that rises from the periphery of the bottom portion; and a cap that covers the head portion when not recording,
A gap larger than the maximum thickness H of the ink droplets attached to the side surface of the head portion expressed by the following formula 1 between the side surface of the head portion and the inner surface of the frame portion of the cap in a state where the cap is put on the head portion. Provided ,
A protrusion made of an elastic body is provided at the front end of the frame portion of the cap, and an annular groove into which the protrusion is fitted is formed on the front end surface of the recording head portion facing the protrusion. The recording head unit is provided with an extrusion mechanism for extruding the protrusion from the annular groove,
The extrusion mechanism includes a shaft rotatably provided on the recording head and a plate-like or flat roller-like extrusion member fixed to the shaft, and the projection is rotated by the extrusion member. An ink jet recording apparatus, wherein the strip is pushed out from the annular groove .

(Where S represents the cross-sectional area [m ² ] of the ink droplet attached to the side surface of the head portion, γ represents the surface tension of the ink droplet [mN / m], and θ represents the distance between the side surface of the head portion and the top surface of the droplet. (The angle formed is [degree], ρ is the density of the droplet [kg / m ² ], and g is the acceleration of gravity [m / s ² ].) The ink jet recording apparatus according to claim 3 , wherein the gap formed between the side surface of the head portion and the inner surface of the frame portion of the cap is 2 mm or more.

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