JP5012765B2 - Head cap - Google Patents

Description

  The present invention relates to a head cap that covers an ejection surface of a liquid ejection head that ejects liquid.

  Patent Document 1 describes an ink jet recording apparatus including an ink jet head and a maintenance unit that performs maintenance of the ink jet head. In this inkjet recording apparatus, the maintenance unit has a cap made of an elastic member such as rubber that covers the nozzle surface (ejection surface) of the inkjet head. Then, by covering the nozzle surface with the cap, it is possible to prevent the ink in the nozzle from drying.

JP 2004-142450 A (FIG. 2)

  According to the ink jet recording apparatus described in Patent Document 1 described above, the cap is formed with an annular protrusion that defines a recess extending in one direction, and the nozzle surface of the ink jet head is covered with the recess of the cap. The cap protrusion is brought into contact with the nozzle surface. In order to ensure airtightness in the cap with an appropriate pressure without damaging the nozzle surface, the annular protrusion of the cap is flexible. For this reason, when the cap expands and contracts greatly in the longitudinal direction due to a change in the environmental temperature, the short side portion of the annular protrusion may fall or deform. In this case, the airtightness in the cap is lowered, and it becomes impossible to prevent the ink in the nozzle from drying.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a head cap that can prevent an annular protrusion abutting against a discharge surface from falling or deforming.

The head cap of the present invention is an annular projection having a substantially rectangular shape in plan view and having two long side portions extending in the longitudinal direction and two short side portions extending in the width direction, On the inner peripheral surface of the annular protrusion, a first step surface orthogonal to the protruding direction of the annular protrusion and a second step surface connecting the tip of the annular protrusion and the first step surface are formed in an annular shape. The annular step surrounding the droplet discharge region formed on the discharge surface by contacting the first step surface with the discharge surface of the droplet discharge head, and the base end of the annular protrusion is connected, And a bottom plate portion that defines a recess together with the annular protrusion. The annular protrusion expands as the width approaches the proximal end from the distal end, so that the width of the proximal end of the short side portion in the longitudinal direction is wider than the width of the proximal end of the long side portion in the width direction. In addition, in the concave portion, an angle formed by the inner peripheral surface on the base end side in the short side portion and the bottom surface of the concave portion is the inner peripheral surface on the base end side in the long side portion and the bottom surface of the concave portion. not greater than the angle of.

According to the present invention, since the width of the base end in the short side portion of the annular protrusion is wider than the width of the base end in the long side portion, the rigidity of the short side portion can be increased. Thereby, when the long side part of the annular projection is greatly expanded and contracted due to the temperature change, it is possible to suppress the short side part from falling or deforming. In addition, since the tip of the annular protrusion can be made thin, the head cap can be reduced in size. Furthermore, it is possible to increase the rigidity of the short side portion by increasing the width of the base end while suppressing the annular protrusion from increasing outward. Thereby, size reduction of a head cap can be achieved.

In this invention, the width | variety regarding the said longitudinal direction of the said 1st level | step difference surface of the said short side part may be wider than the width | variety regarding the said width direction of the said 1st level | step difference surface of the said long side part.

In the present invention, the tip of the annular projection may have the same width over the entire circumference.

  Furthermore, in the present invention, it is preferable that the second step surface is parallel to the protruding direction and can contact at least a part of the side wall surface of the plate on which the discharge surface is formed. According to this, since the two surfaces of the first step surface and the second step surface are in contact with the plate, the droplet discharge region can be reliably sealed.

  According to the present invention, since the width of the base end in the short side portion of the annular protrusion is wider than the width of the base end in the long side portion, the rigidity of the short side portion can be increased. Thereby, when the long side part of the annular projection is greatly expanded and contracted due to the temperature change, it is possible to suppress the short side part from falling or deforming.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the internal configuration of an ink jet printer according to a preferred embodiment of the present invention. FIG. 2 is a schematic plan view showing the internal configuration of the inkjet printer 1. 3 is a cross-sectional view taken along the line III-III shown in FIG. FIG. 4 is a view of the four inkjet heads 2 as viewed from below. As shown in FIGS. 1 to 3, the inkjet printer 1 has a rectangular parallelepiped housing 1 a. In addition, a paper discharge unit 31 is provided at the top of the housing 1a. Furthermore, the inside of the housing 1a is divided into three spaces A, B, and C in order from the top. In the space A, four inkjet heads 2 that respectively eject magenta, cyan, yellow, and black ink, a transport unit 20, and a maintenance unit 70 (the back side of the transport unit 20 in FIG. 1) are arranged. . Spaces B and C are spaces in which a paper feed unit 1b and an ink tank unit 1c that can be attached to and detached from the housing 1a are arranged. In the present embodiment, the sub-scanning direction is a direction parallel to the transport direction when the paper P is transported by the transport unit 20, and the main scanning direction is a direction orthogonal to the sub-scanning direction and along the horizontal plane. Direction.

  Inside the ink jet printer 1, a paper transport path for transporting the paper P from the paper feed unit 1b to the paper discharge unit 31 is formed (thick arrow in FIG. 1). The sheet feeding unit 1 b includes a sheet feeding tray 23 that can store a plurality of sheets P, and a sheet feeding roller 25 attached to the sheet feeding tray 23. The paper feed roller 25 sends out the uppermost paper P among the plurality of papers P stacked and stored in the paper feed tray 23. The paper P delivered by the paper feed roller 25 is guided to the guides 27 a and 27 b and is fed to the transport unit 20 while being sandwiched by the feed roller pair 26.

  The transport unit 20 includes two belt rollers 6, 7, an endless transport belt 8 wound so as to be bridged between both rollers 6, 7, and a tension roller 10. The tension roller 10 applies tension to the conveyor belt 8 by being urged downward in the lower loop of the conveyor belt 8 while being in contact with the inner peripheral surface thereof. The belt roller 7 is a driving roller, and rotates clockwise in FIG. 1 when a driving force is applied from the transport motor M through two gears. The belt roller 6 is a driven roller, and rotates clockwise in FIG. 1 as the conveyor belt 8 travels as the belt roller 7 rotates.

  The outer peripheral surface 8a of the conveyor belt 8 is subjected to silicone treatment and has adhesiveness. A nip roller 5 is disposed at a position facing the belt roller 6 across the conveyance belt 8 on the sheet conveyance path. The nip roller 5 presses the sheet P sent out from the sheet feeding unit 1 b against the outer peripheral surface 8 a of the transport belt 8. The paper P pressed against the outer peripheral surface 8a is conveyed rightward in FIG. 1 while being held on the outer peripheral surface 8a by the adhesive force.

  Further, a separation plate 13 is provided at a position on the sheet conveyance path that faces the belt roller 7 with the conveyance belt 8 interposed therebetween. The peeling plate 13 peels the paper P held on the outer peripheral surface 8a of the transport belt 8 from the outer peripheral surface 8a. The paper P peeled off by the peeling plate 13 is conveyed while being guided by the guides 29a and 29b and sandwiched by the two pairs of feed rollers 28, and from the opening 30 formed in the upper part of the housing 1a to the paper discharge unit 31. Discharged.

  As shown in FIGS. 2 to 4, the four inkjet heads 2 each extend along the main scanning direction and are fixed to the frame-like frame 4 while being adjacent to each other along the paper conveyance direction B. Has been. The frame 4 has support portions 4 a that face the lower surfaces of both end portions in the longitudinal direction of the inkjet head 2. And the support part 4a and the both ends of the inkjet head 2 are being fixed with the screw 50. FIG. A nozzle plate 3 on which an ejection surface 3a for ejecting ink droplets is formed is fixed to the lower end of each inkjet head 2. In other words, the ink jet printer 1 is a line type color ink jet printer in which an ejection region extending in the main scanning direction is formed.

  As shown in FIG. 1, a platen 9 is disposed in the loop of the conveyor belt 8 so as to face the four inkjet heads 2. The upper surface of the platen 9 is in contact with the inner peripheral surface of the upper loop of the conveyor belt 8 and supports this from the inner peripheral side of the conveyor belt 8. Thereby, the outer peripheral surface 8a of the upper loop of the conveying belt 8 and the lower surface of the inkjet head 2, that is, the discharge surface 3a are parallel to each other, and between the discharge surface 3a and the outer peripheral surface 8a of the conveying belt 8. A slight gap is formed. The gap constitutes a part of the paper transport path. When the paper P conveyed while being held on the outer peripheral surface 8a of the transport belt 8 passes immediately below the four ink jet heads 2, the inks of the respective colors are sequentially supplied from the ink jet heads 2 to the upper surface of the paper P. A desired color image is formed on the paper P by being discharged.

  As shown in FIGS. 2 and 3, the frame 4 is supported by a frame moving mechanism 51 provided in the inkjet printer 1 so as to be vertically movable. The frame moving mechanism 51 is disposed on the outer side (upper and lower sides in FIG. 2) of the four inkjet heads 2. Each frame moving mechanism 51 is erected on the frame 4 so as to mesh with a drive motor 52 as a drive source for moving the frame 4 up and down, a pinion gear 53 fixed to the shaft of each drive motor 52, and each pinion gear 53. And a guide 56 disposed at a position where the rack gear 54 is interposed between the rack gear 54 and the pinion gear 53.

  The two drive motors 52 are fixed to the main body frame 1 d of the ink jet printer 1 and are disposed to face each other in the paper transport direction B. The two rack gears 54 extend in the vertical direction, and the lower ends are fixed to the side surfaces of the frame 4. Further, the side surface of the rack gear 54 opposite to the pinion gear 53 is slidably in contact with the guide 56. The guide 56 is fixed to the main body frame 1d.

  In this configuration, when the two drive motors 52 are synchronized and the pinion gears 53 are rotated in the forward and reverse directions, the rack gear 54 moves in the vertical direction. As the rack gear 54 moves up and down, the frame 4 and the four inkjet heads 2 move up and down.

  In addition, guide portions 59 are disposed on both sides of the inkjet head 2 in the longitudinal direction. Each guide part 59 is comprised from the rod-shaped member 58 and a pair of guide 57 which pinches | interposes this. Among these, the pair of guides 57 extend in the vertical direction as shown in FIG. 3 and are respectively fixed to the main body frames 1e facing each other in the direction orthogonal to the paper transport direction B. On the other hand, the bar-shaped member 58 extends in the vertical direction similarly to the guide 57, and is fixed to the side surface of the frame 4 arranged to face the main body frame 1e in parallel. Further, the rod-shaped member 58 is slidably sandwiched between the pair of guides 57. The guide portion 59 can prevent the ejection surface 3a of the inkjet head 2 from being inclined with respect to the outer peripheral surface 8a when the frame 4 is moved in the vertical direction by the frame moving mechanism 51.

  Usually, the frame 4 is arranged at a “printing position” (position shown in FIG. 3) where the four inkjet heads 2 eject ink onto a sheet and perform printing. When the inkjet head 2 is maintained, it is moved by the frame moving mechanism 51 and the four inkjet heads 2 are arranged above the “printing position” (for example, “head maintenance position” described later).

  Each inkjet head 2 is connected to an ink tank 49 in the ink tank unit 1c mounted in the space C. In other words, the four ink tanks 49 store ink ejected from the corresponding inkjet heads 2 respectively. Then, ink is supplied from each ink tank 49 to the inkjet head 2 via a tube (not shown) or the like.

  Next, the maintenance unit 70 that performs maintenance on the inkjet head 2 will be described in detail. As shown in FIGS. 2 and 3, the inkjet printer 1 is provided with a maintenance unit 70 for performing maintenance on the inkjet head 2 on the left side of the inkjet head 2 in FIG. 2. The maintenance unit 70 has two trays 71 and 75 that can move horizontally. Among these, the tray 71 has a substantially square box shape opened upward, and can contain the tray 75. The tray 71 and the tray 75 are detachably coupled by engagement means described later. Both are attached and detached according to the content of the maintenance process.

  The side surface of the tray 71 opposite to the inkjet head 2 is open. When the engagement between the two is released, for example, during a wiping operation, only the tray 71 can be moved, leaving the tray 75. Become. When the maintenance unit 70 moves horizontally as described later, regardless of the engagement state of the engagement means, the frame 4 is previously positioned above the “print position” (in the direction of arrow C in FIG. 3) “head maintenance”. The position for the maintenance unit 70 is secured between the four discharge surfaces 3a and the outer peripheral surface 8a. Thereafter, the maintenance unit 70 is moved horizontally in the direction of arrow D in FIG.

  A waste ink receiving tray 77 is disposed immediately below the maintenance unit 70. The waste ink receiving tray 77 has a size including the tray 71 in a plan view, and even when the tray 71 moves to the right end in FIG. 2, the edge of the tray 71 opposite to the inkjet head 2 overlaps. have. An ink discharge hole 77 a penetrating in the vertical direction is formed at the end of the waste ink receiving tray 77 on the ink jet head 2 side. The ink discharge hole 77a distributes the ink that has flowed onto the waste ink receiving tray 77 to a waste ink reservoir (not shown).

  In the tray 71, a wiper 72 and a tray 75 are arranged in order from the side close to the inkjet head 2. The wiper 72 is made of an elastic material for wiping the ejection surface 3a in the wiping operation, and is disposed so as to extend in parallel with the paper transport direction B. In the tray 75, as shown in FIG. 2, four caps 76 having a rectangular planar shape are provided side by side corresponding to the ejection surface 3a of each inkjet head 2. Each cap 76 has a longitudinal direction parallel to the longitudinal direction of the inkjet head 2, and is arranged in the paper transport direction B at the same pitch as the inkjet head 2.

  The cap 76 will be described in detail with further reference to FIGS. 5A is a plan view of the cap 76, FIG. 5B is a cross-sectional view of the cap 76 taken along the line VB-VB in FIG. 5A, and FIG. It is sectional drawing of the cap 76 regarding the VC-VC line of (c). 6A is a partially enlarged sectional view of the annular protrusion 76a shown in FIG. 5B, and FIG. 6B is a partially enlarged sectional view of the annular protrusion 76a shown in FIG. 5C.

  As shown in FIG. 5, the cap 76 has a substantially rectangular annular protrusion 76a protruding upward, and a bottom plate part 76b having a substantially rectangular shape in plan view to which the base end of the annular protrusion 76a is connected. Yes. The annular protrusion 76a and the bottom plate portion 76b are made of an elastic material such as rubber or resin, and define a concave portion 76c that opens upward as a unit. The recess 76c seals the ejection surface 3a while surrounding the ink ejection area where the nozzle 3b is opened in the ejection surface 3a when the inkjet head 2 is mounted on the cap 76 in the cap operation described later. The annular protrusion 76a has a substantially rectangular shape in plan view, and includes two long side portions extending in the longitudinal direction and two short side portions extending in the width direction.

  As shown in FIGS. 5 and 6, on the inner peripheral surface of the short side portion of the annular protrusion 76a, a first step surface 78a orthogonal to the protruding direction of the annular protrusion 76a, the tip of the annular protrusion 76a, and the first step surface A second step surface 78b that connects 78a is formed. Further, on the inner peripheral surface of the long side portion of the annular protrusion 76a, a first step surface 78c orthogonal to the protruding direction of the annular protrusion 76a and a second step surface connecting the tip of the annular protrusion 76a and the first step surface 78c. 78d is formed. The first step surface 78a and the first step surface 78c are connected to each other to form a ring, and the second step surface 78b and the second step surface 78d are connected to each other to form a ring. When the cap 76 is attached to the inkjet head 2, the lower end (including the ejection surface 3a) of the nozzle plate 3 enters the recess 76c, and the first step surfaces 78a and 78c form the nozzle 3b of the ejection surface 3a. The second step surfaces 78b and 78d are in contact with the side wall surface of the nozzle plate 3 parallel to the protruding direction of the annular protrusion 76a. Thereby, the ink discharge area is surrounded by the first step surfaces 78a and 78c and the second step surfaces 78b and 78d, and the discharge surface 3a is reliably sealed. In FIG. 6, the tip of the annular protrusion 76 a has a plane orthogonal to the protruding direction, but may have a convex curved surface in the protruding direction. Further, the flat surface of the tip has the same width over the entire circumference.

  The width of the short side portion and the long side portion of the annular protrusion 76a becomes wider as it approaches the base end from the front end. That is, the annular protrusion 76a tapers toward the tip. In the recess 76c, the angle θ1 formed by the inner peripheral surface on the short end side of the annular projection 76a and the bottom surface of the recess 76c is the base end side inner peripheral surface of the long side portion of the annular projection 76a and the recess 76c. It is larger than the angle θ2 formed with the bottom surface of. For this reason, the width T1 of the base end in the short side part of the annular protrusion 76a is wider than the width T2 of the base end in the long side part of the annular protrusion 76a. Thereby, the intensity | strength of the short side part of the cyclic | annular protrusion 76a is higher than the long side part.

  The substrate 88 a is a rectangular plate member fixed to the lower surface of the bottom plate portion 76. The substrate 88a is supported by the tray 75 via two springs (elastic members) 88b and urged upward. Accordingly, when the first step surfaces 78a and 78c of the annular protrusion 76a and the discharge surface 3a come into contact with each other, the spring 88b relaxes the impact force. Further, even if there is some error in the parallelism of the annular protrusion 76a with respect to the discharge surface 3a, the annular protrusion 76a can follow the inclination with respect to the discharge surface 3a.

  2 and 3, a holding member 74 holding the wiper 72 is fixed to the tray 71 on the inkjet head 2 side. The holding member 74 has a U-shaped planar shape, and the wiper 72 is held by a portion of the holding member 74 that extends along the paper conveyance direction B. On the other hand, a concave portion 74a constituting an engaging means is formed at the end of the portion of the holding member 74 that extends in the direction orthogonal to the paper transport direction B.

  As described above, the tray 71 and the tray 75 are detachably engaged by the engaging means. The engaging means is installed in the vicinity of the upper and lower sides of the trays 71 and 75 in FIG. 2, and mainly includes a recess 74 a provided in the holding member 74 and a hooking member 83 supported by the tray 75. Has been. The hook member 83 extends in a direction orthogonal to the paper transport direction B, and is supported rotatably at the center. Further, a hook portion 83a that engages with the concave portion 74a is formed at the end of the hook member 83 on the ink jet head 2 side. Above the maintenance unit 70, contact members 84 that can contact the end portions 83b farthest from the inkjet head 2 of the respective hook members 83 are rotatably supported. When these contact members 84 rotate and contact the end portion 83b, the engagement between the hook portion 83a and the recessed portion 74a is released. On the other hand, when the contact member 84 is separated from the end portion 83b, the hook portion 83a engages with the concave portion 74a and returns to the state shown in FIG.

  When maintenance described later is not performed, the maintenance unit 70 stops at a “retracted position” (a left position not facing the inkjet head 2 in FIG. 2) away from the inkjet head 2 as shown in FIG. 3. Yes. When maintenance is performed, the maintenance unit 70 is horizontally moved from the “retracted position” to the “maintenance position” facing the ejection surface 3 a of the inkjet head 2. At this time, since the inkjet head 2 is arranged at the “head maintenance position”, the tips of the wiper 72 and the annular protrusion 76a do not contact the ejection surface 3a.

  During the wiping operation, the tray 75 remains, and only the tray 71 moves from the “retracted position” to the lower portion of the head, and receives the ink wiped by the wiper 72. In the standby state, when the discharge surface 3 a is covered with the cap 76, the tray 71 and the tray 75 are coupled by the engaging means and moved to the “maintenance position”.

  As shown in FIG. 2, the trays 71 and 75 are movably supported by a pair of guide shafts 96 a and 96 b that extend in a direction orthogonal to the paper transport direction B. The tray 71 is provided with two bearing members 97 a and 97 b that protrude from both upper and lower side surfaces of the holding member 74. The tray 75 is provided with two bearing members 98 a and 98 b and protrudes from the upper and lower side surfaces of the tray 75. Further, both ends of the pair of guide shafts 96a and 96b are fixed to the main body frames 1e and 1g, and are arranged in parallel with each other between the frames 1e and 1g. Here, each is fixed with a screw. With such a configuration, the trays 71 and 75 are moved in the left-right direction (arrow D direction) in the figure along the guide shafts 96a and 96b.

  Here, the horizontal movement mechanism 91 that horizontally moves the trays 71 and 75 will be described. As shown in FIG. 2, the horizontal movement mechanism 91 includes a motor 92, a motor pulley 93, an idle pulley 94, a timing belt 95, guide shafts 96a and 96b, and the like. The motor 92 is fixed to a mounting portion 1f formed at an end portion of the main body frame 1e extending parallel to the paper transport direction B with a screw or the like. The motor pulley 93 is connected to the motor 92 and rotates as the motor 92 is driven. The idle pulley 94 is rotatably supported by the leftmost main body frame 1g in FIG. The timing belt 95 is disposed in parallel with the guide shaft 96a and is wound so as to be bridged between the motor pulley 93 and the idle pulley 94 paired therewith. The timing belt 95 is connected to a bearing member 97 a provided on the holding member 74.

  In this configuration, when the motor 92 is driven, the timing belt 95 travels as the motor pulley 93 rotates in the forward or reverse direction. As the timing belt 95 travels, the tray 71 connected to the timing belt 95 via the bearing member 97a moves in the left or right direction in FIG. 2, that is, in the direction toward the “retraction position” or “maintenance position”. When the concave portion 74a of the holding member 74 and the hook portion 83a are engaged, the wiper 72 in the tray 71 and the cap 76 in the tray 75 are together, and the hook portion 83a is separated from the concave portion 74a. Only the wiper 72 in the tray 71 moves.

  Next, the operation of the maintenance unit 70 will be described below with reference to FIGS. FIG. 7A is a situation diagram when the inkjet head 2 is moved from the “printing position” to the “head maintenance position” and the tray 71 of the maintenance unit 70 is moved from the “retraction position” to the “maintenance position”. . FIG. 7B is a situation diagram when the ink attached to the ejection surface 3 a is wiped by the wiper 72. FIG. 8 is a situation diagram when the annular protrusion 76a of the cap 76 is in contact with the discharge surface 3a.

  In the maintenance operation, in order to perform a purge operation for recovering the inkjet head 2 that has fallen into a defective discharge, first, the frame 4 is moved upward by the frame moving mechanism 51 to move the inkjet head 2 to the “head maintenance position”. To place. Thereby, a space in which the maintenance unit 70 can be arranged is formed between the ejection surface 3a and the conveyor belt 8. The ejection surface 3a of the inkjet head 2 in the “head maintenance position” is a position that does not come into contact with the wiper 72 and the tip of the annular protrusion 76a when the maintenance unit 70 moves to the “maintenance position”.

  Then, the abutting member 84 is brought into contact with the end 83b of the hooking member 83 by the horizontal movement mechanism 91 to separate the hooking portion 83a from the concave portion 74a, thereby releasing the engagement therebetween. That is, the connection between the tray 71 and the tray 75 is released. In this state, the horizontal movement mechanism 91 moves the tray 71 from the “retracted position” to the “maintenance position” as shown in FIG.

  Subsequently, in this state, a pump operation for forcibly sending the ink in the ink tank to the inkjet head 2 (both not shown) is driven, and a purge operation for discharging ink from the nozzles 3b of the inkjet head 2 into the tray 71 is performed. Do. By this purging operation, clogging of the nozzle 3b, which has caused a discharge failure, and thickening of the ink in the nozzle 3b are eliminated. The ink ejected into the tray 71 flows into the waste ink receiving tray 77 along the tray 71. Then, ink is discharged from the ink discharge hole 77 a of the waste ink receiving tray 77.

  Subsequently, in order to perform a wiping operation, the inkjet head 2 is moved downward by the frame moving mechanism 51. At this time, when the tray 71 moves to the left in FIG. 7 (that is, the direction from the “maintenance position” to the “retraction position”), the tip of the wiper 72 can come into contact with the ejection surface 3a. It is arranged at a position (wiping position). Then, as shown in FIG. 7B, the tray 71 is moved from the “maintenance position” to the “retracted position” by the horizontal movement mechanism 91.

  In this wiping operation, since the upper end of the wiper 72 is above the ejection surface 3a, the wiper 72 comes into contact with the ejection surface 3a while being bent, and wipes ink adhering to the ejection surface 3a by the purge operation. The ink wiped by the wiper 72 flows into the waste ink receiving tray 77 along the surface of the wiper 72. Then, ink is discharged from the ink discharge hole 77 a of the waste ink receiving tray 77.

  In this way, the inkjet head 2 that has fallen into an ink ejection failure or the like is recovered by the purge operation, and the maintenance operation of wiping the ink attached to the ejection surface 3a by the purge operation by the wipe operation is completed.

  Next, a capping operation for covering the ejection surface 3a with the cap 76 when the inkjet printer 1 is not performing printing on a sheet for a long time will be described below. Also in this case, the frame 4 is moved upward by the frame moving mechanism 51 in the same manner as described above, and the inkjet head 2 is arranged at the “head maintenance position”.

  Then, as shown in FIG. 8, the horizontal movement mechanism 91 moves the tray 71 and the tray 75 from the “retraction position” to the “maintenance position” in a state where the tray 71 and the tray 75 are connected by the hooking member 83. . At this time, the concave portion 76c of the cap 76 is disposed at a position facing the periphery of the formation region of the nozzle 3b. Further, the inkjet head 2 is lowered by the frame moving mechanism 51 to a position (cap position) where the first step surfaces 78a and 78c of the annular protrusion 76a abut against the ejection surface 3a. At this time, the second step surfaces 78b and 78d abut against the side wall surface of the nozzle plate 3 parallel to the protruding direction of the annular protrusion 76a (see FIG. 6). In this way, the ink discharge area on the discharge surface 3a is covered (capped) by the annular protrusion 76a of the cap 76, and the discharge surface 3a is sealed.

  According to the inkjet printer 1 according to the present embodiment as described above, the base end width T1 at the short side portion of the annular protrusion 76a is wider than the base end width T2 at the long side portion of the annular protrusion 76a. As a result, the strength of the short side portion of the annular projection 76a becomes higher than that of the long side portion, and even if the annular projection 76a expands and contracts greatly in the longitudinal direction due to temperature change, the short side portion collapses or deforms. Can be suppressed.

  Moreover, since the annular protrusion 76a is tapered, the cap 76 can be reduced in size.

  Further, in the recess 76c, the angle θ1 formed by the inner peripheral surface on the proximal side in the short side portion and the bottom surface of the recess 76c is larger than the angle θ2 formed by the inner peripheral surface in the long side portion and the bottom surface of the recess 76c. ing. Thereby, it is possible to increase the rigidity of the short side portion while suppressing the annular protrusion 76a from increasing toward the outside, and to reduce the size of the cap 76.

  When the cap 76 is attached to the inkjet head 2, the first step surfaces 78a and 78c are in contact with the peripheral area of the ejection surface 3a where the nozzle 3b is not formed, and the second step surfaces 78b and 78d are annular projections. It contacts the side wall surface of the nozzle plate 3 parallel to the protruding direction of 76a. Thereby, the nozzle 3b is reliably sealed by the recessed part 76c.

  In the present embodiment, the width of the first step surface 78a in the long side direction is wider than the width of the first step surface 78c in the short side direction. Thereby, even if the annular protrusion 76a expands and contracts in the long side direction due to a temperature change, the peripheral area of the discharge surface 3a contacts the first step surfaces 78a and 78c.

<Modification>
A modification of the present invention will be described with reference to FIG. FIG. 9A is a partial enlarged cross-sectional view relating to the short side portion of the annular protrusion 176a, and FIG. 9B is a partial enlarged cross-sectional view relating to the long side portion of the annular protrusion 176a. As shown in FIG. 9, the short side part and the long side part of the annular protrusion 176a of the cap 176 are wall bodies each having a substantially rectangular parallelepiped shape. Further, the first step surface 178a related to the short side portion and the first step surface 178c related to the long side portion have the same width W1. Then, by making the width W2 of the distal end of the short side portion of the annular protrusion 176a wider than the width W3 of the distal end of the long side portion, the width T3 of the base end in the short side portion of the annular protrusion 176a becomes the length of the annular protrusion 176a. It is wider than the base end width T4 at the side. Thereby, the intensity | strength of the short side part of the cyclic | annular protrusion 76a becomes higher than a long side part. According to this, the rigidity of the short side part which concerns on the cyclic | annular protrusion 176a can be made high easily.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, in the above-described embodiment, when the cap 76 is attached to the inkjet head 2, the first step surfaces 78a and 78c abut on the peripheral area where the nozzle 3b of the ejection surface 3a is not formed, and the second The step surfaces 78 b and 78 d abut against the side wall surface of the nozzle plate 3, but when the cap 76 is attached to the inkjet head 2, the second step surfaces 78 b and 78 d abut against the side wall surface of the nozzle plate 3. The structure which does not touch may be sufficient.

  Furthermore, in the above-described embodiment, an example in which the present invention is applied to the ink jet printer 1 has been described. However, the present invention can also be applied to an apparatus having a liquid droplet head that discharges another liquid. In addition, although the inkjet printer 1 has the four caps 76, the cap 76 alone may be an independent configuration.

1 is a schematic cross-sectional side view of an inkjet printer according to an embodiment of the present invention. FIG. 2 is a schematic plan view of a main part of the ink jet printer shown in FIG. 1. It is sectional drawing along the III-III line | wire shown in FIG. It is a figure when the four inkjet heads shown in FIG. 2 are viewed from below. (A) is a top view of the cap shown in FIG. (B) is sectional drawing of the cap regarding a VB-VB line | wire. (C) is sectional drawing of the cap regarding a VC-VC line. It is the elements on larger scale of the cap shown in FIG.5 (b) and FIG.5 (c). 2A is a situation diagram when the inkjet head shown in FIG. 2 is moved from the “printing position” to the “head maintenance position” and the tray of the maintenance unit is moved to the “maintenance position”, and FIG. It is a situation figure when the ink adhering to the discharge surface is wiped off by the wiper shown. FIG. 6 is a situation diagram when the annular protrusion of the cap shown in FIG. 5 is in contact with the discharge surface. It is a figure for demonstrating a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Inkjet head 3 Nozzle plate 3a Discharge surface 3b Nozzle 75 Tray 76 Cap 76b Bottom plate part 76a Annular projection 76c Recessed part 78a, 78c First step surface 78b, 78d Second step surface 88b Spring 88a Substrate

Claims (4)

An annular protrusion having a substantially rectangular shape in plan view and having two long side portions extending in the longitudinal direction and two short side portions extending in the width direction, the inner surface of the annular protrusion The first step surface orthogonal to the projecting direction of the annular protrusion and the second step surface connecting the tip of the annular protrusion and the first step surface are formed in an annular shape, and the first step surface is An annular protrusion surrounding the droplet discharge region formed on the discharge surface by contacting the discharge surface of the droplet discharge head;
A base end of the annular protrusion is connected, and includes a bottom plate portion that defines a recess together with the annular protrusion;
The annular protrusion is
The width of the base side of the short side portion in the longitudinal direction is wider than the width of the base side of the long side portion than the width of the base end in the width direction . The angle between the inner peripheral surface on the base end side in the short side portion and the bottom surface of the recess is larger than the angle between the inner peripheral surface on the base end side in the long side portion and the bottom surface of the recess. A head cap characterized by that. 2. The head cap according to claim 1 , wherein a width in the longitudinal direction of the first step surface of the short side portion is wider than a width in the width direction of the first step surface of the long side portion . The head cap according to claim 1, wherein the tip of the annular protrusion has the same width over the entire circumference . The second step surface is, the projecting direction parallel and any one of claims 1-3, characterized in that the contactable at least a portion of the side wall surface of the plate in which the ejection surface is formed 1 The head cap according to the item.

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