JP2009166357A - Line type inkjet imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a line type inkjet imaging device capable of properly preventing the drying of ink and the attaching of dirts in ink discharge faces of inkjet heads. <P>SOLUTION: The line type inkjet imaging device comprises the plurality of inkjet heads 21-1 or others having the ink discharge faces and caps 41-1 or others facing the ink discharge faces of the respective inkjet heads 21-1 or others from below the a sheet conveying path respectively. The device further comprises a raising and lowering mechanism raising and lowering the respective caps 41-1 or others between evacuate position below the sheet conveying path and a closing position raised from the evacuate position and closing the ink discharge faces of the corresponding inkjet heads 21-1 or others. All the caps 41-1 or others are sorted to two or more of groups, the cap raising and lowering mechanism comprises raising and lowering members such as cams corresponding to every groups respectively can raise and lower all the caps 41-1 or others and can independently raise and lower only the optional cap groups. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a line-type ink jet image forming apparatus in which a plurality of ink jet heads are arranged in a paper width direction perpendicular to the paper transport direction, and caps that are opposed to the ink jet heads are arranged.

  Inkjet image forming apparatuses used as image forming apparatuses such as printers, facsimiles, and copying machines need to prevent drying of the ink jet ink ejection surface when not in use, and to prevent foreign matter from adhering to the ink ejection surface. Therefore, conventionally, an apparatus having a cap capable of closing each ink ejection surface has been developed (Patent Documents 1 and 2).

In the image forming apparatus described in Patent Document 1, an inkjet head (recording head) is configured to be movable in the vertical direction between a recording position and a retracted position, and the ink ejection surface is blocked by a cap at the retracted position. It has become. On the other hand, the image forming apparatus disclosed in Patent Document 2 is configured such that all caps are integrally movable in the vertical direction, and all caps simultaneously block the ink ejection surface when not in use.
JP 7-314701 A JP 2004-142280 A

  In Patent Document 1, since the inkjet head itself is configured to move up and down, when using the inkjet head at the time of printing, it is difficult to always keep the gap between the paper and the inkjet head constant, affecting the print quality, The lifting mechanism of the inkjet head is also complicated. Further, in Patent Document 2, since the entire ink head unit is configured to be closed with an integral cap, there is an unused inkjet head during printing, for example, when printing on narrow paper. Then, the unused ink jet head is left in an open state for a long time, which causes ink to dry, and a recovery operation such as head cleaning is required for the next use. Further, when the recovery operation is based on the ink ejection operation, the ink is wasted.

(Object of invention)
The present invention employs a configuration in which a cap is moved up and down in an image forming operation such as printing, and even when some inkjet heads are not used, only the unused inkjet heads are closed so that the ink on the ink ejection surface It is an object of the present invention to provide a line-type ink jet image forming apparatus that can prevent drying and adhesion of foreign matter, does not require a recovery operation by ejecting ink, and does not waste ink.

  In order to solve the above-described problems, the present invention has an ink ejection surface having a large number of nozzles open on the lower surface, and an inkjet head that faces the paper in the paper conveyance path from above, and is perpendicular to the paper conveyance direction. A plurality of lines arranged in the width direction, provided with a paper transport mechanism on the upstream side in the paper transport direction of the ink jet head, and a line in which a cap is disposed opposite to the ink discharge surface of each ink jet head from below the paper transport path. In the ink jet type image forming apparatus, each of the caps is moved up and down between a retracted position below the paper transport path and a closed position that rises from the retracted position and closes the ink ejection surface of the corresponding inkjet head. A cap lifting mechanism is provided, and all caps are divided into two or more cap groups. Mechanism is provided with the elevating driving members corresponding respectively to each cap group, it is possible to lift the entire cap simultaneously, and is configured so it is also possible to lift only the independently optional cap group.

  According to the above configuration, while the necessary inkjet head is used in the image forming operation, only the unused inkjet head can be closed with the cap, so that the ink on the ink ejection surface of these unused inkjet heads The ink can be prevented from drying out and adhering foreign matter, and no recovery operation by ejecting ink is required, and ink is not consumed wastefully.

  In the ink jet image forming apparatus having the above-described configuration, the present invention is preferably configured such that a movable paper width guide capable of guiding the edge in the width direction of the transport paper when the cap is raised is moved up and down integrally with the cap. It can be possible.

  According to the above configuration, it is possible to raise and lower the paper width guide according to the width of the paper using the cap raising and lowering mechanism, and it is not necessary to provide a new mechanism for raising and lowering the paper width guide. Directional deviation can be suppressed, and printing deviation can be prevented.

  In addition, each cap is provided with a blade member protruding upward from the cap so as to be able to move up and down integrally, and further provided with a reciprocating mechanism for reciprocating each cap in the paper width direction. The cap and the blade member can be raised to a wiping position where the cap is in contact with the ink discharge surface of the inkjet and the cap is not in contact with the ink discharge surface.

  According to the above configuration, since the blade member for cleaning the ink discharge surface is supported using the support structure of the cap, the support structure of the blade member can be simplified.

  The reciprocating mechanism is preferably configured to reciprocate all caps and all blade members integrally.

  According to the above configuration, the ink ejection surfaces of all the inkjet heads can be simultaneously cleaned by one reciprocating mechanism.

[First Embodiment]
1 to 11 show a line-type ink jet image forming apparatus (printing apparatus) according to a first embodiment of the present invention. The first embodiment of the present invention will be described based on these drawings. 1 is a schematic side view of a line-type ink jet image forming apparatus, FIG. 2 is a perspective view of the ink jet head unit and cap of FIG. 1, FIG. 3 is a perspective view of a cap, and FIG. FIG. 5 is a front view showing the left and right reciprocating mechanism together with the cap, and FIG. 5 is an enlarged VV cross-sectional view of FIG. 6 to 11 are enlarged front views of the cams used in the cap lifting mechanism.

  In FIG. 1, the line-type inkjet image forming apparatus includes a sheet feeding unit 2, a transport unit 3, a printing unit 4, and a discharge unit 5 in the apparatus main body 1 in order from the sheet transport start end side (left side in the drawing). The paper receiving unit 6 is detachably attached to the paper transport terminal portion of the apparatus main body 1. The sheet conveyance direction is indicated by a symbol F. For convenience of explanation, the upstream side of the sheet conveyance direction F is referred to as “front side”, and the downstream side of the sheet conveyance direction F is referred to as “rear side”.

  The paper feed unit 2 is disposed at a paper feed table 11 on which a large number of sheets N can be stacked and which can be moved up and down, an abutment plate 12 erected at the rear end of the paper feed table 11, and an upper end portion of the corresponding plate 12. And a pair of left and right side guide plates 15 disposed on the sheet feed table 11. The sheet feeding roller 14 is in contact with the upper surface of the sheet separating member 13. The paper N loaded on the paper base 11 is picked up one by one from the top by the paper feed roller 14 and fed in the transport direction (rear) F.

  The conveyance unit 3 includes a guide plate 16 extending from the paper feed roller 14 to the printing unit 4, a first conveyance roller (conveyance mechanism) 17 disposed at a front end portion of the guide plate 16, and a rear end of the guide plate 16. And a pair of upper and lower skew correction and second transport rollers (transport mechanism) 18 arranged in the section. That is, the sheet N fed from the sheet feeding unit 2 is conveyed rearward on the guide plate 16 by the first conveying roller 17 and is conveyed to the nipping portion (nip portion) of the stopped second conveying roller 18. The leading edge of N is brought into contact, and the first conveying roller 18 is rotated by a certain amount to bend the sheet N upward, thereby correcting the skew of the sheet N, and then the first and second By rotating the transport rollers 17 and 18 at a predetermined speed, the paper N is transported to the printing unit 4 at a predetermined transport speed.

  The printing unit 4 includes two sets of front and rear ink jet head units 21 and 22 above the transport path, and will be described in detail later below the transport path, but from below to the lower end ink discharge surface of the ink jet units 21 and 22. An opposing cap mechanism 23 is provided, and the upper surface of the sheet N fed from the second conveying roller 18 at a predetermined speed is printed by the ink ejected from the ink ejection surface and discharged to the discharge unit 5. It has become.

  The discharge unit 5 includes a belt conveyance mechanism 26 having an air suction box 27, and adsorbs the printed paper N discharged from the printing unit 4 to the upper surface (conveyance surface) of the conveyance belt of the belt conveyance mechanism 26. However, it is conveyed backward and discharged to the paper receiving unit 6.

  The paper receiving unit 6 includes a paper receiving table 30, a stopper 31 erected on the rear end of the paper receiving table 30, and a pair of left and right guide plates 32, and the paper discharged from the discharging unit 5. N is locked by a stopper 31 at the rear end, and the sheet width direction is aligned by a side guide plate 32 so that the sheets are stacked on the sheet receiving table 30 in an orderly manner.

  In FIG. 2, front and rear ink jet head units 21 and 22 are respectively six ink jet heads 21-1, 21-2, 21-3, 21-4, 21-5 arranged at equal intervals in the paper width direction. 21-6 and 22-1, 22-2, 22-3, 22-4, 22-5, 22-6. For simplification of description, the upstream inkjet head unit 21 in the transport direction F is referred to as a “front head unit”, and the downstream inkjet head unit 22 in the transport direction F is referred to as a “rear head unit”. To do. In addition, each of the inkjet heads 21-1, 21-2, 21-3, 21-4, 21-5, and 21-6 of the front head unit 21 is first front and second in order from the left side when viewed from the front. The third, fourth, fifth and sixth ink jet heads, and the respective ink jet heads 22-1, 22-2, 22-3, 22-4, 22-5, 22-6 of the rear head unit 22 Are referred to as rear first, second, third, fourth, fifth and sixth inkjet heads in order from the left as viewed from the front.

  The rear first through sixth ink jet heads 22-1,... 22-6, as viewed in the paper transport direction F, are each half pitch (with respect to the front first through sixth ink jet heads 21-1,. It is arranged at a position shifted to the left by 1/2) of the head-to-head pitch, so that it is possible to print on the paper without any problem in the width direction.

  Although the twelve ink jet heads 21-1,..., 21-6, 22-1,... 22-6 are not shown in the drawing, they are fixed at predetermined positions of the apparatus main body 1 by the head support means. A conveyance path forming guide member 45 is disposed below the heads 21-1, ... 21-6, 22-1, ... 22-6. The guide member 45 has a paper transport surface 45a that is positioned slightly below the lower end ink discharge surface of the ink jet head 21-1 and the like and substantially parallel to the ink discharge surface. It has side guide surfaces 45b for guiding both side edges, and further has a window hole 45c for exposing the lower end ink discharge surface of each inkjet head 21-1 etc. downward. Of the left and right side guide surfaces 45b, the right side guide surface 45b has a function of always guiding the right edge of the paper N regardless of the paper size, but the left side guide surface 45b. Is used as a guide surface for guiding the left edge of the paper when printing a paper of the maximum size, for example, A3 size paper of Japanese Industrial Standard. As will be described in detail, it is not used as a guide surface.

[Cap mechanism 23]
Below the guide member 45, as a cap mechanism 23, front first through first front to first lower to sixth ink jet heads 21-1 to. The sixth caps 41-1,... 41-6 are arranged, and the rear side first so as to face the lower end ink discharge surfaces of the rear side first to sixth inkjet heads 22-1,. First to sixth caps 42-1 to 42-6 are arranged.

  The front first cap 41-1 is supported by the front first elevator 51a, the front second cap 41-2 is supported by the front second elevator 51b, and the front third cap 41-3 is the front third elevator 51c. The front fourth, fifth and sixth caps 41-4, 41-5 and 41-6 are supported by one front fourth lifting platform 51d. Between the adjacent front cap lifting platforms 51a, 51b, 51c, 51d, there is a step-shaped engaging portion that can be engaged in the vertical direction, so that the front first lifting platform 51a It is possible to move up and down independently with respect to the second lifting platform 51b, and it is also possible to move up and down together with the lifting of the second lifting platform 51b. The front second lifting platform 51b can be lifted and lowered independently of the right front third lifting platform 51c, and can be lifted and lowered together with the lifting of the right third lifting platform 51c. . The front third lifting platform 51c can be lifted and lowered independently of the right front fourth lifting platform 51d, and can be lifted and lowered together with the lifting of the right fourth lifting platform 51d. .

  The lifting platforms for the first to sixth caps 42-1, ... 42-6 on the rear side are shown in Figs. 2 and 5 (parts of the first lifting platform 52a and the fifth cap lifting platform 52e). Although only appearing, a rear first lifting platform 52a that supports the rear first cap 42-1 to be movable up and down, and a rear second lifting platform that supports the rear second cap 42-2 to move up and down ( 52b), a rear third lifting platform (52c) that supports the rear third cap 42-3 so as to be movable up and down, and a rear fourth lifting platform (the rear fourth cap 42-4 that supports the rear fourth cap 42-4 so as to be movable up and down). 52d) and a rear fifth lift platform 52e that supports the rear fifth and sixth caps 42-5 and 42-6 so as to be movable up and down. Each rear lifting platform 52a, 52b, 52c, 52d, 52e is engaged by a step-like engaging portion that can be engaged in the vertical direction similarly to the front lifting platform, and is the same as the front lifting platform. In addition, the rear first lifting platform 52a at the left end can be moved up and down independently, and sequentially go to the right rear lifting platform, independently from the other rear lifting platform located on the right side, and The rear lifting platform located on the left side can be moved up and down integrally.

  3, the upper end surfaces of the caps 41-1,... 41-6, 42-1,..., 42-6 are formed in a rectangular frame shape, and the inkjet heads 21-1,. 6, 22-1,... 22-6 can come into contact with the outer peripheral edge of the ink discharge surface. On the left side of each cap 41-1, ... 41-6, 42-1, ... 42-6, a cleaning rubber blade 71 projecting upward from the upper end of the cap is disposed, respectively, and a corresponding lifting platform 51a, etc. Are raised and lowered together with the corresponding lifting platform 51a and the like. Further, the right side of the rear first to fourth caps 42-1, 42-2, 42-3 and the right side of the front second cap 41-2 are lower than the blade 71 but higher than the upper end surface of the cap. Each of the movable paper width guides 72 is arranged on the corresponding lifting platform 52a, 52b, 52c, 52d and 51b, and can be lifted and lowered together with the corresponding lifting platform. The movable paper width guide 72 on the rear first lifting platform 52a is used as a side guide for guiding the left edge of B4 size paper, and the movable paper width guide 72 on the rear second lifting platform 52b is The movable paper width guide 72 on the front second lifting platform 51b is used as a side guide for guiding the left edge of the B5 size paper. The movable sheet width guide 72 on the rear third lifting platform 52c is used as a side guide for guiding the left edge of the A5 size sheet, and the movable sheet width guide 72 on the rear fourth lifting platform 52d. Is used as a side guide for guiding the left edge of postcard-sized paper.

[Cap lifting mechanism]
In FIG. 5, the cap mechanism 23 is integrally provided with a lower housing 48 and an upper housing 49, and a cam type cap lifting mechanism 50 is provided in the housings 48, 49.
In FIG. 3, a horizontal front cam shaft 61 extending in the left-right direction is disposed below the front first to fourth elevating platforms 51a,... 51d. Front first to fourth cams 62a, 62b, 62c, and 62d that are in contact with the lower surfaces of the lifting platforms 51a,. A horizontal rear camshaft 63 extending in the left-right direction is disposed below the rear first to fourth elevating platforms 52a,... 52e, and the rear camshaft 63 has rear first to fifth rear sides. The rear first to fifth cams 64a, 64b, 64c, 64d, and 64e are fixedly attached to the lower surfaces of the lifting platforms 52a,. Front and rear stepping motors 65 and 66 are connected to the right ends of the front and rear cam shafts 61 and 63 so that the cam shafts 61 and 63 are rotated by a predetermined angle. Not electrically connected to the control device.

  6 is a rear first cam 64a, FIG. 7 is a front first cam 62a and a rear second cam 64b, FIG. 8 is a front second cam 62b, FIG. 9 is a rear third cam 64c, and FIG. FIG. 11 shows the cam shapes of the third cam 62c and the rear fourth cam 64d, and FIG. 11 shows the front fourth cam 62d and the rear fifth cam 64e. Each of the cams 62a to 64e includes a retracting cam surface S1 on the cam base circumference, a cleaning cam surface S2 having a cam height higher than the retracting cam surface S1, and a cam height higher than the cleaning cam surface S2. The closing cam surface S3 and the retracting cam surface S1 are formed in different ranges (rotational angle ranges) according to the use timing of the cams 62a to 64e. .

  Each of the cams 62a,... 64e has a corresponding front first cap 41-1 as in the state of the front first cam 62a in FIG. The upper end surface of the guide member 45 is lowered to a retracted position below the sheet conveying surface 45a. When the closing cam surface S3 is in the closing rotation state positioned directly above, the upper end surface of the corresponding rear first cap 42-1 corresponds to the corresponding rear first cap 42-1 as in the state of the rear first cam 64a in FIG. The sheet width guide 72 is raised above the sheet conveying surface 45a of the guide member 45 while being raised to the closing position where it contacts the lower end ink ejection surface of the inkjet head 22-1. Further, when the cleaning cam surface S2 is in the cleaning rotation state positioned directly above, the lower end ink discharge of the inkjet head 21-1 or the like corresponding to the upper end portion of the corresponding cleaning rubber blade 71 as shown in FIG. Raise it to the cleaning position where it touches the surface lightly. In the cleaning rotation state, the upper end of the paper width guide 72 is positioned below the lower end ink discharge surface of the ink jet head 21-1 and the like, and the transport path forming guide member 45 and the paper width guide 72 are formed so as not to interfere with each other. Yes.

  Each of the cams 62a to 64e rotates synchronously by a predetermined angle in the direction of the arrow R with reference to the rotation reference angle (θ1) shown in FIGS. 6 to 11, and is thereby controlled in eight stages from the rotation angles θ1 to θ8. It is like that.

  At the first rotation angle (rotation reference angle) θ1, all the cams 62a to 64e are in the retracted rotation state, thereby lowering all the caps 41-1,. All the inkjet heads 21-1,... 22-6 are maintained in the usable open state.

  At the second rotation angle θ2, only the rear first cam 64a in FIG. 6 is in the closed rotation state, thereby raising the rear first cap 42-1 to the closed position, and the rear first inkjet head 22- Only one ink ejection surface is closed. The remaining front-side first to fourth cams 62a to 62d and rear-side second to fifth cams 64b to 64e are maintained in the retracted rotation state as in the case of the first rotation angle θ1, and the corresponding front-side cap 41- 1 to 41-6 and the rear caps 42-2 to 42-6 are lowered to the retracted position. That is, the corresponding front inkjet heads 21-1 to 21-6 and the rear inkjet heads 22-2 to 22-6 are maintained in an open state in which they can be used.

  At the third rotation angle θ3, the front first cam 62a and the rear second cam 64b shown in FIG. 7 are in the closed rotation state from the state of the second rotation angle θ2. As a result, the front first cap 41-1 and the rear second cap 42-2 also rise to the closed position, and as a whole, the front first inkjet head 21-1, the rear first and second inkjet heads 22-1, The ink discharge surface 22-2 is closed. The remaining front ink jet heads 21-2 to 21-6 and rear ink jet heads 23-3 to 22-6 are maintained in a usable open state, similarly to the rotation angle θ2.

  At the fourth rotation angle θ4, the front second cam 62b shown in FIG. 8 is also in the closed rotation state from the state of the third rotation angle θ3. As a result, the front second cap 41-2 also rises to the closed position, and as a whole, the rear first and second inkjet heads 22-1, 22-2 and the front first and second inkjet heads 21-1, 21-21. 2 ink ejection surface is closed. The remaining front ink jet heads 21-3 to 21-6 and rear ink jet heads 23-3 to 22-6 are maintained in a usable open state as in the case of the rotation angle θ3.

  At the fifth rotation angle θ5, the rear third cam 64c shown in FIG. 9 also enters the closed rotation state from the state of the fourth rotation angle θ4. As a result, the rear third cap 42-3 also rises to the closed position, and as a whole, the rear first to third ink jet heads 22-1, 22-2, 22-3 and the front first and second ink jet heads 21. -1, 21-2 are closed. The remaining front ink jet heads 21-3 to 21-6 and rear sides 22-4 to 22-6 are maintained in a usable open state as in the case of the rotation angle θ4.

  At the sixth rotation angle θ6, from the state of the fifth rotation angle θ5, the rear fourth cam 64d and the front third cam 62c shown in FIG. 10 are also in the closed rotation state. Accordingly, the rear side fourth cap 42-4 and the front side third cap 41-3 are also raised to the closed position, and as a whole, the rear side first to fourth inkjet heads 22-1, 22-2, 22-3, 22-4 and the first to third ink jet heads 21-1, 21-2, and 21-3 on the front side are closed. The remaining front ink jet heads 21-4 to 21-6 and the rear ink jet heads 22-5 and 22-6 are maintained in a usable open state as in the case of the rotation angle θ5.

  At the seventh rotation angle θ7, all the cams 62a,... 64e are in the closed rotation state, all the caps 41-1,... 42-6 are raised to the closed position, and all the inkjet heads 21-1. ,..., 22-6 is closed.

  At the eighth rotation angle (rotation reference angle) θ8, all the cams 62a,... 64e are in the cleaning rotation state, and all the caps 41-1,. Descend to

[Right and left reciprocating mechanism 76]
The cap mechanism 23 is provided with a reciprocating mechanism 76 having the following configuration in order to reciprocate the rubber blades 71 left and right together with the caps 41-1,. Yes. As shown in FIG. 4, the lower housing 48 and the upper housing 49 (virtual line) are supported on the guide rail surface 75 so as to be movable in the left-right direction, and are also provided with a rotary solenoid via the rack-and-pinion reciprocating mechanism 76. It is linked to 78 or a forward / reverse motor, and reciprocates left and right by a distance in the left-right direction substantially corresponding to the left-right width of the ink ejection surface. The rack-and-pinion reciprocating mechanism 76 includes a rack 77 that is fixed to the lower housing 48 and extends to the left, and a pinion 79 that meshes with the rack 77 and is fixed to the output shaft of the rotary solenoid 78. .

[Action]
(1) First, an outline of image forming work by the image forming apparatus, that is, printing work will be described. In FIG. 1, the sheets N stacked on the sheet feeding table 11 of the sheet feeding unit 2 are fed one by one from the top to the transport unit 3 by the sheet feeding roller 14 and the separating member 13. In the transport unit 3, first, the first transport roller 17 transports backward on the guide plate 16, and the leading end of the paper N is brought into contact with the holding unit of the stopped second transport roller 18, and further, a certain amount By rotating the first conveying roller 17 to bend the sheet N upward, thereby correcting the skew of the sheet N, the first and second conveying rollers 17 and 18 are rotated at a predetermined speed. The paper N is transported to the printing unit 4 at a predetermined transport speed. In the printing unit 4, the upper surface of the paper N is printed by the front and rear head units 21, 22 and discharged to the discharge unit 5. In the discharge unit 5, the sheet N is conveyed backward while being adsorbed on the conveyance belt, and is discharged to the paper receiving unit 6.

(2) In the printing unit 4, the paper N is transported on the horizontal paper transport surface 45 a shown in FIG. 2 and the like. Depending on the dimensions of the paper N, the left and right guide widths and the number of inkjet heads to be used Are adjusted and unused inkjet heads are closed by corresponding caps. The adjustment method will be specifically described below.

  When printing on A3 size paper N, the cam shafts 61 and 63 are set to the first rotation angle θ1 shown in FIGS. Accordingly, all the caps 41-1,... 42-6 are located at the retracted position, and all the ink jet heads 21-1,... 22-6 are in an open state usable for printing. Further, as the side guides at the left and right left edges of the paper N, the left and right side guide surfaces 45b of the guide plate 45 in FIG.

  When printing on B4-size paper N, the cam shafts 61 and 63 are rotated to the second rotation angle θ2 shown in FIGS. 6 to 11, and the rear first cap 64a is used by the rear first cam 64a. Only 42-1 is raised to the closing position, and only the ink ejection surface of the first inkjet head 22-1 on the rear side is closed. In this case, the paper width guide 72 (see FIG. 4) provided on the first lifting platform 52a on the rear side guides the left edge of the B4 paper.

  When printing on the A4 size paper N, the cam shafts 61 and 63 are rotated to the third rotation angle θ3 shown in FIGS. Thus, in addition to the rear first cap 42-1, the front first cap 41-1 and the rear second cap 42-2 are provided by the front first cam 62a and the rear second cam 64b. Are also raised to the closing position, and the ink ejection surfaces of the first inkjet head 21-1 on the front side and the second inkjet head 22-2 on the rear side are also blocked together with the first inkjet head 22-1 on the rear side. At this time, the sheet width guide 72 (see FIG. 4) provided in the second lifting platform 52b on the rear side guides the left edge of the A4 sheet.

  When printing on B5 size paper N, the camshafts 61 and 63 are rotated to the fourth rotation angle θ4 shown in FIGS. As a result, in addition to the first and second caps 42-1 and 42-2 on the rear side and the first cap 41-1 on the front side, the second cap 41-2 on the front side is also closed by the second cam 62b on the front side. The ink ejection surface of the front side second ink jet head 21-2 is raised together with the rear side first and second ink jet heads 22-1, 22-2 and the front side first ink jet head 21-1. Block. At this time, the sheet width guide 72 (see FIG. 4) provided on the front second lifting platform 51b guides the left edge of the B5 sheet.

  When printing on A5 size paper N, the cam shafts 61 and 63 are rotated to the fifth rotation angle θ5 shown in FIGS. Thus, in addition to the first and second caps 42-1 and 42-2 on the rear side and the first and second caps 41-1 and 41-2 on the front side, the third cam 64c on the rear side causes the rear side to The third cap 42-3 is also raised to the closed position, together with the first and second inkjet heads 22-1, 22-2 on the rear side and the first and second inkjet heads 21-1, 21-2 on the front side. The ink ejection surface of the rear third inkjet head 22-3 is also closed. At this time, the sheet width guide 72 (see FIG. 4) provided on the rear third lifting platform 52c guides the left edge of the A5 sheet.

  When printing on a postcard-size paper N, the cam shafts 61 and 63 are rotated to a sixth rotation angle θ6 shown in FIGS. Thus, in addition to the first, second, and third caps 42-1, 42-2, 42-3 on the rear side and the first and second caps 41-1, 41-2 on the front side, the fourth on the rear side. The rear side fourth cap 42-4 and the front side third cap 41-3 are also raised to the closed position by the cam 64d and the front side third cam 62c, and the rear side first, second and third ink jets are raised. Together with the heads 22-1, 22-2, 22-3 and the first and second inkjet heads 21-1, 21-2 on the front side, the fourth inkjet head 22-4 on the rear side and the third inkjet head on the front side The ink discharge surface 21-3 is also closed. At this time, the paper width guide 72 (see FIG. 4) provided on the rear fourth elevating platform 52d guides the left edge of the postcard.

  When cleaning the head units 21 and 22, the cam shafts 61 and 63 are rotated to the eighth rotation angle θ8 shown in FIGS. As a result, all the cams 62a,... 64e are in the cleaning rotation state, and as shown in FIG. 4, all the caps 41-1, ... 42-6 are lowered to the cleaning position. In this state, by driving the reciprocating mechanism 76, all the cleaning rubber blades 71 are reciprocated to the left and right to clean the ink ejection surfaces of the corresponding inkjet heads 21-1,. To do.

  When the apparatus is stored in a non-use state, the cam shafts 61 and 63 are rotated to the seventh rotation angle θ7 shown in FIGS. As a result, all the cams 62a,... 64e are in the closed rotation state, and all the caps 41-1,... 42-6 are raised to the closed position, and all the ink jet heads 21-1,. Block the ink ejection surface.

[Second Embodiment]
FIG. 12 shows a second embodiment of the present invention. As a cap raising / lowering mechanism, instead of the cam-type cap raising / lowering mechanism of the first embodiment, a plurality of link types that can be vertically expanded and contracted on the lower housing 48 are shown. A cap lifting mechanism 80 is provided. Each link type cap raising / lowering mechanism 80 is arrange | positioned similarly to arrangement | positioning of each cam of 1st Embodiment, for example. Each link type cap elevating mechanism 80 has a drive screw 81 screwed into a nut portion formed at a connecting portion between link members, and each drive screw 81 is rotationally driven by an appropriate drive mechanism. The type cap lifting mechanism 80 is vertically expanded and retracted, and the desired caps 41-1,... 42-6 are moved up and down between the retracted position, the cleaning position, and the closing position via the lifting platforms 51a. Structures other than the cap lifting mechanism are the same as those in the first embodiment, and the same components are denoted by the same reference numerals.

[Third Embodiment]
FIG. 13 shows a third embodiment of the present invention, which is provided with a plurality of chain-type cap lifting mechanisms 89 as a cap lifting mechanism instead of the cam-type cap lifting mechanism of the first embodiment. Each chain type cap elevating mechanism 89 is arranged in the same manner as the arrangement of each cam in the first embodiment. The chain-type cap elevating mechanism 89 is rotatably supported by a compression spring 86 that supports each elevating platform 51a and the like so as to be movable up and down, a chain 87 having one end connected to the lower surface of each elevating platform 51a and the like, and the lower housing 48. Drive sprocket 88 and a tension spring 85 connected to the other end of the chain 87.

  Each chain 87 extends downward from the lower surface of each lifting platform 51a and the like, is wound around each drive sprocket 88, then reverses upward, and is connected to a tension spring 85. The tension spring 85 is connected to the upper housing. 49 is supported by a support plate 49a provided at 49. Each drive sprocket 88 is fixed to the output shaft 91a of the stepping motor 91. By rotating the drive sprocket 88 by a predetermined angle by the stepping motor 91, the desired cap 41-1, ... 42-6 etc. are moved up and down between the retracted position, the cleaning position and the closing position. Structures other than the cap lifting mechanism are the same as those in the first embodiment, and the same components are denoted by the same reference numerals.

[Fourth Embodiment]
FIG. 14 shows a fourth embodiment of the present invention, which is provided with a cylinder type cap elevating mechanism 95 as a cap elevating mechanism instead of the cam type elevating mechanism of the first embodiment. Each cylinder type cap raising / lowering mechanism 95 is arranged in the same manner as the arrangement of each cam in the first embodiment. Each cylinder-type cap lifting mechanism 95 is connected to a fluid supply device such as a compressor (not shown), and the desired caps 41-1,... Move up and down between position and closed position. A pneumatic cylinder is preferably used as the cylinder type cap lifting mechanism 95, but a hydraulic cylinder can also be used. Structures other than the cap lifting mechanism are the same as those in the first embodiment, and the same components are denoted by the same reference numerals.

[Other embodiments]
(1) In each of the above embodiments, the inkjet units 21 and 22 are arranged in two rows in the front and rear, but the present invention can also be applied to a structure in which three or more rows are arranged in the front and rear.
(2) A pattern for dividing a plurality of inkjet heads into a plurality of elevating groups is not limited to the division pattern shown in the above embodiment, and an appropriate division pattern can be adopted according to the size of the paper to be used. .

  The present invention is applicable to various image forming apparatuses such as a printer, a copying machine, and a printing machine.

1 is a schematic side view of a line-type inkjet image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a perspective view of an ink jet head unit and a cap of the line type ink jet image forming apparatus of FIG. 1. FIG. 2 is a perspective view of a cap of the line type inkjet image forming apparatus of FIG. 1. FIG. 2 is a front view showing a reciprocating mechanism together with an ink jet head unit and a cap of the line type ink jet image forming apparatus of FIG. 1. It is a VV cross-sectional enlarged view of FIG. It is an enlarged front view of the cam used for a cap raising / lowering mechanism. It is an enlarged front view of another cam used for a cap raising / lowering mechanism. It is an enlarged front view of another cam used for a cap raising / lowering mechanism. It is an enlarged front view of another cam used for a cap raising / lowering mechanism. It is an enlarged front view of another cam used for a cap raising / lowering mechanism. It is an enlarged front view of another cam used for a cap raising / lowering mechanism. It is a cross-sectional enlarged view similar to FIG. 5 which shows the modification of a cap raising / lowering mechanism. It is a cross-sectional enlarged view similar to FIG. 5 which shows another modification of a cap raising / lowering mechanism. It is a cross-sectional enlarged view similar to FIG. 5 which shows another modification of a cap raising / lowering mechanism.

Explanation of symbols

2 Paper feed unit 3 Transport unit (transport mechanism)
4 Printing section 21, 22 Inkjet head unit 21-1, ... 21-6 Front inkjet head 22-1, ... 22-6 Rear inkjet head 23 Cap mechanism 41-1, ... 41-6 Front cap 42-1, ... 42-6 Rear cap 50 Cam type cap lifting mechanism 61 Front cam shaft 62a, ... 62d Front cam 63 Rear cam shaft 64a, ... 64e Rear cam 71 Rubber blade for cleaning 72 Movable paper width guide (guide portion)
76 Rack and pinion mechanism (reciprocating mechanism)
80 Link type cap lifting mechanism 89 Chain type cap lifting mechanism 95 Cylinder type cap lifting mechanism

Claims (4)

A plurality of inkjet heads having an ink ejection surface with a large number of nozzles open on the lower surface and facing the sheet in the sheet conveyance path from above are arranged in the sheet width direction perpendicular to the sheet conveyance direction. In a line-type inkjet image forming apparatus that includes a sheet conveyance mechanism on the upstream side in the sheet conveyance direction, and has caps that are respectively opposed to the ink ejection surfaces of the inkjet heads from below the sheet conveyance path.
A cap lifting mechanism that lifts and lowers each cap between a retracted position below the paper transport path and a closed position that rises from the retracted position and closes the ink ejection surface of the corresponding inkjet head;
All caps are divided into two or more cap groups, and the cap lifting mechanism is provided with a lifting drive member corresponding to each cap group, so that all caps can be lifted and lowered at the same time, and only any cap group is independent. A line-type ink jet image forming apparatus, which is configured to be movable up and down. The line-type inkjet image forming apparatus according to claim 1,
A line-type ink jet image forming apparatus, in which an arbitrary cap is provided with a sheet width guide capable of guiding an edge in a width direction of a conveyance sheet when the cap is lifted up and down integrally with the cap. The line type inkjet image forming apparatus according to claim 1,
Each cap is equipped with a blade member protruding upward from the cap so that it can be moved up and down integrally,
A reciprocating mechanism for reciprocally moving each cap in the paper width direction,
The lifting mechanism is a line-type inkjet image forming apparatus in which the cap and blade member can be raised to a wiping position where each blade member abuts against an ink jet ink ejection surface and the cap does not abut against the ink ejection surface. .   The reciprocating mechanism is a line-type inkjet image forming apparatus configured to reciprocate all caps and all blade members integrally.

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