Inkjet printing apparatus

Abstract

Disclosed is an inkjet printing apparatus including a connection switching device in a housing having external suction ports and an internal suction port being disposed at an equal distance from the center of rotation of a switching section, the external suction ports being connectable to a plurality of lines, the internal suction port being connected to a suction path for sucking the interior of the housing. The connection switching device selectively connects any of the plurality of external suction ports to the suction device by rotating the switching section Consequently, when the switching section is connected to the internal suction port, the interior of the housing is sucked, whereby ink is sucked from all the inkjet nozzles.

Claims

1. An inkjet printing apparatus with a plurality of inkjet heads having a plurality of inkjet nozzles being arranged in a row; a plurality of caps for the plurality of inkjet heads respectively; a plurality of lines in communication with the plurality of caps respectively; and a suction device sucking ink from the plurality of inkjet nozzles via the plurality of caps and the plurality of lines, the inkjet printing apparatus comprising: a housing having a plurality of external suction ports, an internal suction port and an ink-draw-off port, the plurality of external suction ports being connected to the plurality of caps via the plurality of lines; a switching section disposed in the housing and having an internal communication path in communication with the suction device; a connection switching device for selectively connecting the switching section to any port of the plurality of external suction ports or the internal suction port by moving the switching section to a position where the communication path is brought into communication with any port of the plurality of external suction ports or the internal suction port; and a suction path disposed out of the housing for connecting the internal suction port to the ink-draw-off port for sucking an interior of the housing, wherein the ink in the housing is discharged from the ink draw off port to a suction line through the suction path and the internal suction port.

2. The inkjet printing apparatus according to claim 1, wherein the housing comprises the draw-off port of the suction path on the bottom of the housing, the suction path sucking the interior of the housing.

3. The inkjet printing apparatus according to claim 1, wherein the housing comprises the suction path sucking the interior of the housing.

4. The inkjet printing apparatus according to claim 3, wherein the plurality of inkjet heads is provided for every single-color ink.

5. The inkjet printing apparatus of claim 1, wherein the housing comprises the plurality of external suction ports arranged radially.

6. The inkjet printing apparatus of claim 5, wherein the switching section has an L-shape, and wherein a first end of the switching section is configured to rotate, whereas a second end thereof is configured to communicate with each of the plurality of external suction ports.

7. The inkjet printing apparatus according to claim 6, wherein the housing comprises a closed bearing at the center of rotation of the switching section.

8. The inkjet printing apparatus of claim 1, wherein the housing comprises the plurality of external suction ports arranged coaxially.

9. The inkjet printing apparatus according to claim 8, wherein the switching section has a crank shape, and a first end of the switching section is configured to rotate, whereas a second end thereof is configured to communicate with each of the plurality of external suction ports.

10. The inkjet printing apparatus according to claim 9, wherein the housing comprises a closed bearing at the center of rotation of the switching section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an explanatory view of an inkjet printing apparatus 100.

(2) FIGS. 2 and 3 are explanatory views each illustrating an ejector 3.

(3) FIGS. 4 and 5 are explanatory views each illustrating an external structure of a connection switching section 315.

(4) FIG. 6 is an explanatory view for suction of a group of inkjet nozzles by an operation of the connection switching section 315.

(5) FIG. 7 is an explanatory view of another aspect of the connection switching section 315.

(6) FIG. 8 is an explanatory view of a housing 315′h of the connection switching section 315.

DETAILED DESCRIPTION

(7) Description will be given hereinafter of examples of this invention with reference to the drawings.

Example 1

(8) FIG. 1 illustrates an inkjet printing apparatus 100 according to one example of this invention. The inkjet printing apparatus 100 performs printing by ejecting ink onto a roll sheet to be transported. The inkjet printing apparatus 100 includes a controller 1, a transporting section 2, an ejector 3, a drying section 4, and an inspecting section 5.

(9) The controller 1 controls the inkjet printing apparatus 1 entirely. The controller 1 controls transportation of a sheet 9 by the transporting section 2, ejection of ink onto the sheet 9 by the ejector 3 or cleaning in the ejector 3, drying of the sheet 9 with the ink ejected thereon by the drying section 4, imaging of a printing image on the sheet 9 by the inspecting section 5. Such control achieves printing onto the sheet 9 by the inkjet printing apparatus 100.

(10) The transporting section 2 transports the sheet 9 in the inkjet printing apparatus 100. The transporting section 2 includes a sheet accommodating section 20, a drive roller 21, and a support roller 22.

(11) The sheet accommodating section 20 accommodates the sheet 9 as a roll sheet to be printed. A sheet accommodating section 20a accommodates the printing sheet 9 prior to printing, and a sheet accommodating section 20b accommodates the sheet 9 subsequent to the printing.

(12) The sheet 9 fed out from the sheet accommodating section 20a is transported to the ejector 3, the drying section 4, and the inspecting section 5 with drive rollers 21a and 21b while being supported by the support roller 22. Then the sheet 9 is wound up in the sheet accommodating section 20b.

(13) The ejector 3 receives ink from an ink tank, not shown. The ejector 3 ejects the ink in response to drive signals generated by the controller 1 in accordance with image information, thereby performing printing onto the sheet 9.

(14) The ejector 3 includes a plurality of inkjet nozzle groups 30k, 30c, 30m, and 30y. The inkjet nozzle groups 30k, 30c, 30m, and 30y extend perpendicularly relative to a transport direction of the sheet 9. Arrangement of many nozzles in a row achieves a width of ejection more than a width of the sheet 9 to be transported. Such a construction of the ejector 3 achieves printing by one-time ejection without performing reciprocated scanning in a width direction of the sheet 9 to be transported.

(15) Here, the number of inkjet nozzle groups in the ejector 3 is limited to four, but may be one for single-color ejection. Moreover, the number of inkjet nozzle groups may be five or more for additional special-color ejection.

(16) The drying section 4 heats the sheet 9 subsequent to printing by the ejector 3 with use of a heater, a dryer, and the like, to evaporate solvent of ink (mainly, water). Consequently, the ink is fixed.

(17) The drying section 4 includes a construction of oscillating radiation. Consequently, when radiation-curable ink, such as an ultraviolet-curable ink, is ejected from the ejector 3, the ink is fixed (cured) on the sheet 9.

(18) The inspecting section 5 takes printing images so as to determine whether or not the controller 1 performs printing onto the sheet 9 satisfactorily. The inspecting section 5 takes a printing image 5 printed on the sheet 9 to be transported with use of a CCD line sensor or a CCD camera, and then transmits information on the image to the controller 1. The controller 1 compares the image information used for ink ejection with photographic information to determine an ejection failure in the ejector 3. This enables to determine whether or not the printing is performed satisfactorily.

(19) Here, the ejection failure is, for example, no-ink ejection from the nozzle, failure in spraying of ink droplets, or failure in size of ink droplets. When the controller 1 determines such an ejection failure in the ejector 3, the controller 1 performs cleaning of the ejector 3.

(20) FIGS. 2 and 3 are schematic views of the ejector 3 to which cleaning is performed. FIG. 2 illustrates the ejector 3 performing printing onto the sheet 9, whereas FIG. 3 illustrates the ejector 3 to which the cleaning is performed.

(21) The ejector 3 includes a cleaning section 31 for cleaning an inkjet nozzle group. The cleaning section 31 has a suction cap 311, a suction tube 312, an electromagnetic on/off valve 313, a suction pump 314, a connection switching section 315, and a suction line 316.

(22) Here, description will be given assuming that eight inkjet heads 30a to 30h are arranged in a row to form one inkjet nozzle group 30. Of course, the number of inkjet heads arranged in a row to form the inkjet nozzle group 30 of is limited to eight.

(23) Moreover, for explanation purposes, the ejector 3 includes one cleaning section 31 for one inkjet nozzle group 30. In actual, the ejector 3 includes a plurality of cleaning sections 31 for a plurality of inkjet nozzle groups 30, respectively.

(24) The suction cap 311 covers the inkjet nozzle group 30 so as to prevent the nozzles from being dried or contaminated. The suction cap 311 includes the suction tube 312 connected to the suction pump 314. The suction cap 311 performs covering as illustrated in FIG. 3 while the controller 1 controls the inkjet nozzle group 30 to move downward. This allows suction for eliminating ink clogging in the inkjet nozzle group 30.

(25) Here, suction caps 311a to 311h are provided for inkjet heads 30a to 30h, respectively.

(26) The suction tube 312 is connected to the suction cap 311 as noted above. The suction pump 314 sucks ink via the suction tube 312 from the inkjet nozzle group 30 covered with the suction cap 311.

(27) Here, suction tubes 312a to 312h are provided for the suction caps 311a to 311h, respectively, and are connected to the connection switching section 315 so as to allow suction.

(28) In addition, a suction tube 312z is not connected to the suction cap 311 directly, but is connected to the switching section 315 so as to suck the interior of the connection switching section 315.

(29) This achieves suction of ink from the suction caps 311a to 311h. Details thereof are to be mentioned later.

(30) The electromagnetic on/off valve 313 is disposed on the suction line 316 via which the suction pump 314 and the connection switching section 315 are connected. As illustrated in FIG. 2, the controller 1 controls the electromagnetic on/off valve 313 to close the suction line 316 while the inkjet nozzle group 30 performs ejection to the sheet 9. As illustrated in FIG. 3, when the ink is sucked from the inkjet heads 30a to 30h while the suction cap 311 covers the inkjet nozzle group 30 and the connection switching section 315 switchingly connects the suction pump 314 to the suction tubes 312a to 312h, the controller 1 controls the electromagnetic on/off valve 313 to open the suction line 316. Details thereof are to be mentioned later.

(31) In addition, when the suction pump 314 collectively sucks ink from the inkjet heads 30a to 30h while the switching section 315 switchingly connects the suction tube 312z, the controller 1 controls the electromagnetic on/off valve 313 to open the suction line 316. Details thereof are to be mentioned later.

(32) The suction pump 314 sucks the ink from the inkjet nozzle group 30 through the suction line 316, the connection switching section 315, the suction tube 312a to 312h or 312z, and the suction cap 311 under the state as in FIG. 3. When the suction pump 314 generates negative pressure, ink is discharged from the inkjet nozzle group 30. The ink discharged due to negative pressure is accumulated in a drain tank, not shown, of the inkjet printing apparatus 100 through the suction cap 311, the suction tube 312, the connection switching section 315, the suction line 316, and the suction pump 314.

(33) When the suction pump 314 sucks the ink in the inkjet nozzle group 30, the controller 1 controls the connection switching section 315 to switch the suction line 316 and the suction tube 312a to 312h or 312z so as to individually suck the inkjet heads 30a to 30h forming the inkjet nozzle group 30 or collectively suck the inkjet heads 30a to 30h.

(34) The connection switching section 315 is to be described in detail hereinafter with reference to FIGS. 4 and 5.

(35) FIG. 4 illustrates an external construction of the connection switching section 315. The switching section 315 includes a housing 315 for sealingly accommodating therein a switching section 315k (not shown in this drawing) communicated with the suction line 316. The housing 315h includes a plurality of suction ports 315i for connecting the suction tubes 312a to 312h, and 312z.

(36) The housing 315h includes a sealed bearing 315j that enables to rotate the switching section 315k. The bearing 315j allows rotating the switching section 315k by a motor, not shown, while the interior of the housing 315h is kept sealed.

(37) The plurality of suction ports 315i are disposed radially along the outer periphery of the housing 315h so as to correspond to the suction tubes 312a to 312h, and 312z.

(38) Specifically, a suction port 315ia is connected to be in communication with the suction tube 312a. A suction port 315ib is connected to be in communication with the suction tube 312b. Hereinafter, similar connection is performed, and the suction port 315ih is similarly connected to be in communication with the suction tube 312h.

(39) Moreover, the suction port 315iz is connected to be in communication with the suction tube 312z. Here, the suction tube 312z is connected to be in communication not with the inkjet nozzle group 30 but with an ink draw-off port 315o provided on the housing 315h.

(40) The ink draw-off port 315o draws off the ink accumulated in the housing 315h when the inkjet nozzle group 30 is entirely sucked, which is to be mentioned later. The ink draw-off port 315o is preferably disposed on the bottom of the housing 315h for a suitable position of drawing off the accumulated ink, the position being in a negative (−) Y-axis direction when the direction is represented by X-, Y-, and Z-axes.

(41) The housing 315h can be made from stainless steel, titanium, or fluorocarbon resin, the material having resistance to pressure upon suction by the suction pump 314 and resistance to corrosion from ink.

(42) FIG. 5 is an explanatory view of an internal construction of the connection switching section 315. The connection switching section 315 includes inside thereof a rotatable switching section 315k communicated with the suction line 316.

(43) The switching section 315k has a substantially L-shape. The controller 1 controls the switching section 315k to rotate by the motor, not shown, whereby the switching section 315k is slidingly engaged in each of the plurality of suction ports 315i. When the switching section 315k is engaged in the suction port 315i, the suction tube 312 is brought into communication with the suction line 316. Consequently, the suction pump 314 enables to suck the ink from the inkjet nozzle group 30 covered with the suction cap 311.

(44) The site where the switching section 315k is engaged in the suction port 315i preferably has a sealing construction, such as a grease seal, a rubber seal, or a metal seal, for obtaining efficient suction or entire suction of the inkjet nozzle group 30, to be mentioned later.

(45) The plurality of suction ports 315ia to 315ih is connected to be in communication with the suction tubes 312a to 312h, respectively. The suction tube 312z connected to the suction port 315iz is connected to be in communication with the ink draw-off port 315o provided on the bottom of the housing 315h as illustrated. Such connection causes the switching section 315k to be slidingly engaged in the suction port 315iz, thereby bringing the suction tube 312z to be in communication with the suction line 316. Consequently, the suction pump 314 enables to suck the interior of the housing 315h.

(46) FIG. 6 is an explanatory view of suction of the inkjet nozzle group 30 by the connection switching section 315.

(47) FIG. 6(a) illustrates an interior housing 315h for explanation of sucking the inkjet heads 30a to 30h individually when the cleaning section 31 performs cleaning to the inkjet nozzle group 30. Here, the switching section 315 performs operations for sucking the ink in the inkjet head 30a.

(48) The controller 1 controls the switching section 315k to rotate and be slidingly engaged in the suction port 315ia while the ejector 3 is in the state as illustrated in FIG. 3. Accordingly, the suction tube 312a is brought into communication with the suction line 316. Thereafter, the electromagnetic on/off valve 313 is made “open” so as the suction pump 314 to start suction, whereby a sliding engaged portion is sealed and the suction line 316 has negative pressure. The negative pressure causes the ink to be discharged from the inkjet head 30a covered with the suction cap 311a via the suction tube 312a communicated with the suction line 316. The discharged ink is sucked by the suction pump 314 through the suction cap 311a and the suction tube 312a to be accumulated in the drain tank, not shown, of the inkjet printing apparatus 100.

(49) When the ink is sucked from each of the inkjet heads 30b to 30h, the controller 1 controls the switching section 315k to rotate and be slidingly engaged in each of the suction ports 315ib to 315ih, thereby opening the electromagnetic on/off valve 313 and performing suction by the suction pump 314. Consequently, similar to the inkjet head 30a, the ink can be sucked from each of the inkjet heads 30b to 30h.

(50) FIG. 6(a) illustrates ink suction. The suction is preferable for cleaning the inkjet nozzle group 30 by the cleaning section 31, especially for cleaning each of the inkjet heads 30a to 30h in a defective condition.

(51) On the other hand, many number of inkjet heads forming the inkjet nozzle group 30 requires much time to repeatedly perform the operation as in FIG. 6(a) for sucking the ink from all of the inkjet heads. This is because the ink has to be sucked from every inkjet head.

(52) For instance, when ink is sucked in a manner as illustrated in FIG. 6(a), it needs time until pressure within the suction cap 311 returns into atmospheric pressure in order to eliminate redundant ink ejection due to the negative pressure. Assuming that the time is around ten seconds for one inkjet head and the number of inkjet heads is eight, idling time of eighty seconds occurs during a cleaning process.

(53) In order to solve the problem above, the housing 315h of the cleaning section 31 includes the ink draw-off port 315o for sucking the interior of the housing 315h.

(54) FIG. 6(b) illustrates an interior housing 315h for explanation of sucking the inkjet heads 30a to 30h collectively when the cleaning section 31 performs cleaning to the inkjet nozzle group 30. Here, the switching section 315 performs operations for sucking the ink entirely from the inkjet nozzle group 30.

(55) The controller 1 controls the switching section 315k to rotate and be slidingly engaged in the suction port 315iz while the ejector 3 is in the state as illustrated in FIG. 3. Accordingly, the suction tube 312z is brought into communication with the suction line 316, the suction tube 312z being connected to be in communication with the ink draw-off port 315o. Thereafter, the electromagnetic on/off valve 313 is made “open” so as the suction pump 314 to start suction, whereby a sliding engaged site is sealed and the suction line 316 has negative pressure. Accordingly, the interior of the housing 315h where the ink draw-off port 315o passes also has negative pressure.

(56) Here, the housing 315h has a sealed construction. Consequently, negative pressure within the housing 315h is also applied to the suction caps 311a to 311h via the suction tubes 312a to 312h connected to the suction ports 315ia, respectively. This causes the ink to be discharged from the inkjet heads 30a to 30h.

(57) The ink discharged from the inkjet heads 30a to 30h flows into the housing 315h via the suction caps 311a to 311h, the suction tubes 312a to 312h, and the suction ports 315ia to 315ih.

(58) The ink flown into the housing 315h is discharged through the ink draw-off port 315o into the suction port 315iz. Here, the ink draw-off port 315o disposed on the bottom of the housing 315h collects the ink accumulated within the housing 315h naturally, resulting in efficient ink suction.

(59) Thereafter, the ink is sucked by the suction pump 314 from the ink draw-off port 315o through the suction tube 312z and then through the switching section 315k slidingly engaged in the suction port 315iz. Accordingly, the ink is accumulated in the drain tank, not shown, of the inkjet printing apparatus 100.

(60) As noted above, ink suction illustrated in FIG. 6(b) causes all the inkjet heads 30a to 30h to be cleaned for a short period of time when the cleaning section 31 performs cleaning to the inkjet nozzle group 30.

(61) As noted above, the cleaning section 31 in FIG. 2 of the inkjet printing apparatus. 100 in FIG. 1 includes the connection switching section 315 in FIGS. 4 and 5. Consequently, when the switching section 315k is connected to any of the suction ports 315ia to 315ih, the ink is sucked from any of the inkjet heads 30a to 30h. When the switching section 315k is connected to the suction port 315iz, the interior of the housing 315h is sucked via the ink draw-off port 315o, whereby the ink is sucked from the entire inkjet nozzle group 30. As a result, reduction in ink consumption due to the suction purge of the inkjet head in no need of suction purge can be achieved. Moreover, rapid cleaning can be performed selectively to the plurality of inkjet heads.

(62) Moreover, ink accumulated in the suction caps 311a to 311 is sucked as in FIG. 6(b) not only by ink suction from the inkjet nozzle group 30 but also by flushing or pressure purge performed to the inkjet nozzle group 30 by the controller 1. Consequently, the ink can be prevented from flowing out of the suction cap 311.

Example 2

(63) Description has been given of the housing 315h of the connection switching section 315, the housing being substantially cylindrical and having a plurality of suction ports 315i along the outer periphery thereof. The location of the plurality of suction ports 315i in the housing 315h is not limited to this.

(64) FIG. 7 is an explanatory view of another aspect of the connection switching section 315.

(65) In a housing 3150h of the connection switching section 315 illustrated in FIG. 7(a), a plurality of suction ports 3150i is not arranged along the outer periphery of the housing 3150h but is arranged coaxially and parallel to the center axis of the housing 3150h having a substantially cylindrical shape. The plurality of suction ports 3150i is arranged in a direction opposite to the suction line 316. In this case, an ink ejection port 3150o also enables to be disposed on the bottom of the housing 3150h.

(66) FIG. 7(b) illustrates the connection switching section 315 seen from the suction line 316. Here, a disk and an outer peripheral surface of the suction line 316 in a suction side of the housing 3150h are illustrated by dotted lines for explanation purposes.

(67) The switching section 3150k in FIG. 7(b) differs from that in FIG. 5 in shape. That is, the switching section 3150k has a substantially crank shape. The switching section 3150k is also in communication with the suction line 316. The controller 1 controls a motor, not shown, to rotate, thereby engaging the switching section 3150k in a plurality of suction ports 3150i formed in the housing 3150h.

(68) The site where the switching section 3150k is slidingly engaged in the suction port 3150i preferably has a sealing construction, such as a grease seal, a rubber seal, or a metal seal, for obtaining efficient suction or entire suction of the inkjet nozzle group 30.

(69) In the connection switching section 315 in FIG. 7, the suction line 316 and the plurality of suction ports 3150i are arranged substantially coaxially. This reduces a storage space in a Y-axis direction. In the inkjet printing apparatus 100, reduction in ink consumption due to the suction purge of the inkjet head in no need of suction purge can be achieved. Moreover, rapid cleaning can be performed selectively to the plurality of inkjet heads.

Example 3

(70) Description has been given of the housing 315h or 3150h of the connection switching section 315 including ink draw-off port 315o or 3150o and suction port 315iz or 3150iz being connected to the suction tube 312z communicated with the ink draw-off port 315o or 3150o. Alternatively, the housing 315h or 3150h itself may include a suction path achieving the same function as the suction tube 312z.

(71) FIG. 8 illustrates a housing 315′k of a connection switching section 315′. The housing 315′h includes a plurality of suction port 315′i formed by suction ports 315′ia to 315′ih on suction tubes 312a to 312h. Here, an ink draw-off port 315′o is communicated with the suction port 315′iz via a suction path 315′v formed on the housing 315′h.

(72) In the inkjet printing apparatus 100, such a construction as above allows reduction in ink consumption due to the suction purge of the inkjet head having no need for suction purge can be achieved. Moreover, rapid cleaning can be performed selectively to the plurality of inkjet heads.

(73) Modification

(74) Description has been given of the housing 315h of the connection switching section 315 having a substantially cylindrical shape. Alternatively, the housing 315h may have a substantially cone, spherical zone, or spherical crown shape. Specifically, the housing 315h may have a shape with a plurality of suction ports 315i being arranged at an equal distance from the center of rotation of the switching section 315k. In this case, the similar effect as above can be produced.

(75) In addition, description has been given of the connection switching section 315 disposed in the cleaning section 31 such that the switching section 315k has the center of rotation in a substantially horizontal direction. Alternatively, the connection switching section 315 may be disposed such that the switching section 315k has the center of rotation in a substantially vertical direction.

(76) In this case, the ink draw-off port 315o on the bottom of the housing 315h causes the ink to be flown naturally and to be further accumulated. Consequently, the ink can be sucked efficiently from the entire inkjet nozzle group 30. Especially, the housing 315h having a substantially cone or spherical crown shape enables to increase efficiency.

(77) Here, the solvent of ink to be cleaned by use in the inkjet printing apparatus 100 is not limited to water.

(78) Moreover, the ink to be cleaned by use in the inkjet printing apparatus 100 may be not only dye ink used for general inkjet printing but also pigment ink.

(79) Moreover, the ink to be cleaned by use in the inkjet printing apparatus 100 may be not only ink used for general printing but also functional ink used for circuit-pattern formation, biological tissue preparation, or three-dimensional shaping.

INDUSTRIAL UTILITY

(80) As noted above, this invention is suitable to an inkjet printing apparatus.

DESCRIPTION OF REFERENCES

(81) 1 controller 2 transporting section 3 ejector 4 drying section 5 inspecting section 9 sheet 30, 30k, 30c, 30m, 30y inkjet nozzle group 31 cleaning section 311, 311a, 311b, 311c, 311d, 311e, 311f, 311g, 311h suction cap 312, 312a, 312b, 312c, 312d, 312e, 312f, 312g, 312h, 312z suction tube 313 electromagnetic on/off valve 314 suction pump 315 connection switching section 316 suction line 315h, 315′h 3150h housing 315i, 315ia, 315ib, 315ic, 315id, 315ie, 315if, 315ig, 315ih, 315iz, 3150i suction port 315k, 315′k, 3150k switching section 315j closed bearing 315o, 315′o, 3150o ink draw-off port