This application is based upon, and claims the benefit of priority from, corresponding Japanese Patent Application No. 2013-136605, filed in the Japan Patent Office on Jun. 28, 2013, the entire contents of which are incorporated herein by reference.
Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
A recording apparatus such as a facsimile, a copier, and a printer is constituted so as to record an image to a recording medium such as a paper and an OHP sheet. The recording apparatus can be classified into an ink jet type, a wire dot type, a thermal type, or a similar type depending on a recording method. An ink jet recording method is classified into a serial type and a line head type. The serial type performs recording by scanning a recording head on a recording medium. The line head type performs recording with the recording head secured to an apparatus main body.
An ink-jet recording apparatus of line head type includes line head type inkjet heads (recording heads) for respective colors. The inkjet heads each have discharge nozzles. The discharge nozzles align at predetermined intervals across a whole print region width perpendicular to a conveyance direction of a recording medium. The ink-jet recording apparatus of line head type discharges ink from the discharge nozzles corresponding to a printing position in synchronization with a conveyance of the recording medium, thus ensuring printing on the whole recording medium.
This ink-jet recording apparatus may cause deterioration of straightness of ink (flying curve), discharge failure, or a similar failure due to deterioration of printing performance of the recording head. This occurs probably due to generation of an abnormal meniscus. The abnormal meniscus is caused by: a foreign object such as paper powder, dust, and dirt generated during conveyance of a paper sheet, a minute ink droplet (hereinafter referred to as mist), which is discharged together with ink droplet for image recording or mist bounced when the ink droplet attaches the recording medium, being attached to the ink discharge face of the recording head. The probable causes of the failure are also: reduction in sealability when mounting a cap due to drying of the mist attached to the cap mounted portion, and an increase of viscosity of the ink in the nozzle in association with the deterioration of sealing performance.
Therefore, to prevent drying of ink in the ink discharge nozzles that have openings at the ink discharge face of recording head or clogging of the nozzle due to increased viscosity of ink inside of the ink discharge nozzle, the following constitution that performs a recovery process is employed. The constitution forcibly discharges (purges) ink from the nozzle, the ink attached to the ink discharge face (nozzle face) is wiped off with a blade-shaped wiper, thus performing a recovery process of the recording head. However, with only simple purge operation and wiping operation, it is difficult to completely remove ink whose viscosity has been increased and dried mist. In particular, the more a solid constituent that the ink contains, the more the viscosity of ink tends to increase. Accordingly, wiping off the ink with the wiper becomes difficult.
Therefore, methods for efficiently removing ink attached to the ink discharge face have been variously proposed. For example, the following inkjet head cleaning apparatus is known. The cleaning apparatus includes a suction nozzle. The suction nozzle includes ink-repellent surfaces, an ink-affinitive surface, and a plurality of suction ports. The ink-affinitive surface is concaved with respect to the ink-repellent surfaces and has smaller contact angle of ink than the contact angle of the ink-repellent surfaces. The plurality of suction ports are formed on the ink-affinitive surface.
The following image forming apparatus of ink jet type is known. The image forming apparatus includes a receiving unit and an application member. The receiving unit receives ink discharged from an ink discharge unit. The application member applies ink on an ink discharge face by movement of the receiving unit while contacting the ink discharge face. The image forming apparatus performs the following steps. Ink is attached to the receiving unit of the application member. The ink adhered to the receiving unit is applied to the ink discharge face. The ink discharge face to which ink is applied is wiped with a wiping member.
Furthermore, the following ink jet printer is known. The ink jet printer generates airflow flowing from a box body to an ink discharge face by ink discharge from a first nozzle array arranged at the ink discharge face to a passing port of the box body. Then, the ink newly attached to the ink discharge face is applied broadly by the airflow. This reduces viscosity increase in ink at the nozzle discharge port so as to prevent clogging.
A recovery system for a recording head according to the disclosure includes a recording head, at least one wiper, at least one application member, a driving mechanism, and a control unit for controlling the operation of at least the at least one application member and the at least one wiper. The recording head includes a nozzle region where a discharge nozzle has an opening. The nozzle region is configured to discharge ink onto a recording medium. The wiper is configured to pressure-contact a wiping start position outside the nozzle region and to wipe an ink discharge face in a predetermined direction, the ink discharge face including the nozzle region. The application member is configured to apply and spread ink discharged from the nozzle region over the ink discharge face. The driving mechanism is configured to reciprocate the wiper along the ink discharge face and move the wiper in an approaching or separating direction with respect to the ink discharge face. The application member is stopped for a predetermined time at a stop position facing one end of the nozzle region at a predetermined distance from the nozzle region on as to hold the ink discharged from the nozzle region between an upper end face of the application member and a whole region in a width direction of the ink discharge face. The application member is configured to move from the stop position along the ink discharge face so as to apply the ink over the ink discharge face while holding the ink between the upper end face of the application member and the ink discharge face. The wiper is configured to move along the ink discharge face so as to wipe off the ink while contacting the ink discharge face over which the ink is applied.
These as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description with reference where appropriate to the accompanying drawings. Further, it should be understood that the description provided in this summary section and elsewhere in this document is intended to illustrate the claimed subject matter by way of example and not by way of limitation.
These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
Example apparatuses are described herein. Other example embodiments or features may further be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. In the following detailed description, reference is made to the accompanying drawings, which form a part thereof.
The example embodiments described herein are not meant to be limiting. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the drawings, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.
Hereafter, a description will be given of the embodiments of the disclosure with reference to the drawings.
As illustrated in
The first conveyance unit 5 and the recording unit 9 are arranged on the downstream side of the paper feed roller 3 and the driven roller 4 (the right side of
Locating the first driving roller 6 on the downstream side of the paper sheet conveyance direction causes the first driving rollers 6 to stretch a conveyance surface of the first conveyance belt 8 (the upper side face of
The recording unit 9 includes a head housing 10 and line heads 11C, 11M, 11Y and 11K held by the head housing 10. These line heads 11C to 11K are supported at a height where a predetermined interval, for example 1 mm, is formed with respect to the conveyance surface of the first conveyance belt 8. As illustrated in
As illustrated in
As illustrated in
The recording heads 17a to 17c each include a water repellent membrane 73, which covers the portions other than the discharge port 18a of the ink discharge face F, a pressurization chamber 75, which is housed for each discharge port 18a, a nozzle channel 76, which communicates with the pressurization chamber 75 and the ink discharge nozzle 18, and a common channel 77, which supplies ink to a plurality of the pressurization chamber 75 from an ink tank 20 (see
Each piezoelectric element 71 is individually driven by applying a drive pulse generated in a drive pulse generating unit (not illustrated) of a head driving unit on the individual electrode 83. Deformation of the piezoelectric element 71 by this drive is transmitted to the vibration sheet 80, and the pressurization chamber 75 is compressed by the deformation of the vibration sheet 80. As a result, pressure is applied on ink in the pressurization chamber 75 to discharge ink, which passed through the nozzle channel 76 and the ink discharge nozzle 18, from the discharge port 18a on a paper sheet as ink droplets. While no ink droplets are being discharged, ink remains in the ink discharge nozzle 18, and the ink forms a meniscus surface M in the ink discharge nozzle 18.
Four color inks (cyan, magenta, yellow, and black) stored in the respective ink tanks 20 (see
Corresponding to the received image data from an external computer or similar unit, each of the recording heads 17a to 17c discharges ink from the ink discharge nozzle 18 toward the paper sheet P, which is conveyed while being suctioned and held to the conveyance surface of the first conveyance belt 8. This forms a color image, which is superposed four color inks, cyan, magenta, yellow and black, on the paper sheet P on the first conveyance belt 8.
In order to prevent a poor ink discharge due to dried or clogged recording heads 17a to 17c, the purge is performed to discharge the ink with high viscosity in the nozzle from the nozzles to prepare for further printing operation as follows. The purge discharges ink from all the ink discharge nozzle 18 of the recording heads 17a to 17c when initial printing after long-term suspension; and the purge discharges ink from ink the ink discharge nozzles 18 of the recording heads 17a to 17c of which ink discharge amount is equal to or less than a predetermined value between printing operation.
Various methods may be employed for the ink discharge method from the recording heads 17a to 17c. Examples include a piezo method, which discharges ink using a piezoelectric element (not illustrated), and a thermal inkjet printing system, which discharges ink by generating bubble with heating element to apply pressure.
Back to
The paper sheet P having an ink image recorded by the recording unit 9 is sent to the second conveyance unit 12, and the ink discharged on the surface of the paper sheet P is dried while passing via the second conveyance unit 12. A maintenance unit 19, as a recovery system, and a cap unit 90 are arranged below the second conveyance unit 12. The maintenance unit 19 moves under the recording unit 9 when performing the purge described above, wipes off the ink discharged from the ink discharge nozzle 18 of the recording heads 17a to 17c, and recovers the wiped ink. The cap unit 90 horizontally moves under the recording unit 9 when capping the ink discharge face F (see
A discharge roller pair 16, which discharges the paper sheet P on which an image is recorded, to the outside of the apparatus main body, is located at the downstream side of the second conveyance unit 12 with respect to the paper sheet conveyance direction. At the downstream side of the discharge roller pair 16, a discharge tray (not illustrated), where the paper sheet P discharged to the outside of the apparatus main body is stacked, is located.
Subsequently, the following describes the ink supply from the ink tanks 20 to the recording heads 17a to 17c during printing, and the discharge of ink from the recording heads 17a to 17c during purging.
As illustrated in
The first supply channel 23 includes an inflow side valve 27, and the second supply channel 25 includes an outflow side valve 29. Opening or closing the inflow side valve 27 allows and regulates the movement of the ink in the first supply channel 23. Opening or closing the outflow side valve 29 allows and regulates the movement of the ink in the second supply channel 25.
The syringe pump 21 includes a cylinder 21a and a piston 21b. The cylinder 21a is connected to the first supply channel 23 and the second supply channel 25. An ink 22 in the ink tank 20 flows into the cylinder 21a via the first supply channel 23. The ink is supplied from the cylinder 21a via the second supply channel 25, and the supplied ink is supplied to the recording heads 17a to 17c and discharged to a nozzle region R on the ink discharge face F from the ink discharge nozzle 18.
The piston 21b is vertically movable by a drive apparatus (not illustrated). A packing (not illustrated), such as O-ring, is attached to the outer peripheral of the piston 21b to prevent ink leakage from the cylinder 21a, and also allows the piston 21b to slide smoothly along the inner circumferential surface of the cylinder 21a.
During the normal operation (when printing), the inflow side valve 27 and the outflow side valve 29 are open as illustrated in
A rack gear 38, which engages an input gear 43 (see
The first wipers 35a to 35c are members to wipe off the ink discharged from the ink discharge nozzles 18 of the respective recording heads 17a to 17c. The first wipers 35a to 35c are brought into pressure contact from an approximately vertical direction on a wiping start position outside the nozzle region R (see
Four first wipers 35a are secured to the second stay 33a at approximately equal intervals. Similarly, four first wipers 35b and four first wipers 35c are respectively secured to the second stays 33b and 33c at approximately equal intervals. The first wipers 35a and 35c are arranged at the positions corresponding to the respective recording heads 17a and 17c (see
Gap rollers 37 are located on four locations of the top faces of the second stays 33a and 33c. The gap rollers 37 contact the head housing 10 of the recording unit 9 when lifting the wiping mechanism 30 to the recording unit 9 side in order to perform the wiping operation of the ink discharge faces F of the recording heads 17a to 17c by the first wipers 35a to 35c. This causes the first wipers 35a to 35c to keep a constant contact with the ink discharge faces F.
As illustrated in
The ink discharge face F is wiped by the first wipers 35a to 35c. Waste ink dropped to the tray surfaces 44b and 44c is collected in the groove portion 44a, then flows toward the ink discharge hole 44d in the groove portion 44a. Subsequently, the waste ink passes via an ink collecting channel (not illustrated) connected to the ink discharge hole 44d, and is collected in a waste ink collection tank (not illustrated).
The following describes an elevating mechanism 50 for lifting the wiping mechanism 30 according to the first embodiment.
Rotating clockwise the shaft 50b of the elevating mechanism 50 in the right side and rotating anticlockwise the shaft 50b of the elevating mechanism 50 in the left side from the position of
On the other hand, rotating anticlockwise the shaft 50b of the elevating mechanism 50 in the right side and rotating clockwise the shaft 50b of the elevating mechanism 50 in the left side from the position of
The following describes the recovery operation for the recording heads 17a to 17c using the wiping mechanism 30 according to the first embodiment in the ink-jet recording apparatus 100 of the disclosure.
When performing the recovery operation for the recording heads 17a to 17c, the first conveyance unit 5 positioned under the recording unit 9 is lifted down first as illustrated in
Prior to the wiping operation, the first wipers 35a to 35c are positioned at stop positions P (positions having a predetermined distance from the end portions of the nozzle regions R of the ink discharge faces F of the recording heads 17a to 17c). Specifically, the supporting frame 40 and the carriage 31 are lifted by rotating the shafts 50b of the elevating mechanism 50 so as to erect the lifting members 50a toward the arrow B direction as illustrated in
Subsequently, closing the inflow side valve 27 (see
As illustrated in
After the first wipers 35a to 35c are positioned opposing the ink discharge faces F at a predetermined spacing, the ink 22 is discharged from the nozzle regions R to be held on the upper end faces of the first wipers 35a to 35c. However, the first wipers 35a to 35c may be brought in close to the ink discharge faces F so as to contact the ink 22 after discharging the ink 22.
However, with a procedure to bring the first wipers 35a to 35c close to the ink discharge faces F after discharging the ink 22, especially if the ink discharge surfaces F 22 have high water repellency, the ink 22 discharged on the ink discharge face F may drop or has a high viscosity as dryness progresses before contacting the first wipers 35a to 35c. As described above, it is preferred to follow the procedure to discharge the ink 22 after positioning the first wipers 35a to 35c opposed to the ink discharge faces F with a predetermined interval because the ink 22 does not drop or dry and is surely held in throughout the counter face region of the upper end faces of the first wipers 35a to 35c and the ink discharge face F.
The first wipers 35a to 35c are stopped for a certain time until the ink 22 spreads through the whole counter face regions of the upper end faces of the first wipers 35a to 35c and the ink discharge faces F. Subsequently, the first wipers 35a to 35c are moved to end edges (a first end edge) of the ink discharge faces F of the opposite direction (upstream side of the wiping direction) of the nozzle regions R while keeping the distance from the ink discharge faces F. Specifically, the carriage 31 is moved to the arrow A′ direction by rotating the input gear 43 (see
While maintaining the distance from the ink discharge faces F, the first wipers 35a to 35c are moved to end edges (a second end edge) of the ink discharge faces F of the opposite direction (the downstream side of the wiping direction) from the positions of the first wipers 35a to 35c in
Subsequently, the wiping operation to wipe off the ink 22 discharged on the ink discharge face F is performed. Specifically, as illustrated in
The supporting frame 40 and the carriage 31 are lifted more upwards than those in the state in
Rotating the input gear 43 (see
The first wipers 35a to 35c move to the end portions of the downstream side of the ink discharge faces F of the respective recording heads 17a to 17c (the right end of
When attaching the cap unit 90 to the recording heads 17a to 17c, first of all, a first conveyance unit 5 positioned to face the inferior face of the recording unit 9 is lifted down as illustrated in
Subsequently, the cap unit 90 is pushed up by lifting the first conveyance unit 5. Stopping the elevation of the first conveyance unit 5 when the cap unit 90 is set in close contact with the recording heads 17a to 17c completes the attachment of the cap unit 90.
According to the configuration of this embodiment, the ink 22 is applied and spreads over the whole ink discharge faces F by moving the first wipers 35a to 35c while holding the ink 22 between the upper end faces of the first wipers 35a to 35c and the ink discharge faces F facing the upper end faces of the first wipers 35a to 35c. Therefore, the first wipers 35a to 35c can wipe off the dried mist and foreign object, such as paper dust, adhering to other than the nozzle region R, by re-dispersing in the ink 22 immediately after discharge.
Mist adhered to the upstream side of the nozzle region R can be removed by moving the first wipers 35a to 35c, where the ink 22 is held on the whole counter face regions thereof facing the ink discharge faces F, to the end edges of the upstream side of the wiping direction of the ink discharge faces F. Therefore, since mist adhered to regions of the ink discharge surfaces F where the cap unit 90 contacts can also be removed, reduction in sealability when mounting the cap unit 90 due to adhered mist can be effectively suppressed.
According to this configuration, the ink 22 that contacts the narrow groove width portions of the concave portions 60 spreads toward the broad side of the groove width (the left side of
The second wipers 39a to 39c project upward (the ink discharge face F side) with respect to the first wipers 35a to 35c. As illustrated in
Similarly to the first embodiment, moving the first wipers 35a to 35c from the state of
This allows an operation of moving the carriage 31 once to the wiping direction to apply and wipe off the ink 22 on the ink discharge faces F of the recording heads 17a to 17c. As a result, a wiping time can be shortened compared with the first embodiment where the ink 22 is wiped using the first wipers 35a to 35c.
A certain time may be required to re-disperse the dried mist in the ink 22. In the second embodiment, the ink 22 applied and spread by the first wipers 35a to 35c are immediately wiped off by the second wipers 39a to 39c. Thus, it is preferred configuration to perform an ink wiping process after moving the first wipers 35a to 35c to the upstream side of the wiping direction after completing the ink 22 application process in a manner such as the first embodiment in order to ensure enough time (interval) for dispersing the dried mist in the ink 22.
Note that, in the second embodiment, the first wipers 35a to 35c are only used to apply and spread the ink 22 over the whole ink discharge faces F. The second wipers 39a to 39c wipe off the ink on the ink discharge faces F. An applying member that holds the ink 22 discharged on the ink discharge faces F and spreads the ink 22 on the ink discharge face F may be provided instead of the first wipers 35a to 35c. Some examples of this kind of application member include a metal member or synthetic resin member that includes the concave portions 60 to hold ink on the upper end faces (see
It will be appreciated that the disclosure will not be limited to the embodiments described above, but many variations thereof are possible without departing from the spirit of the disclosure. For example, as an ink application process, the above respective embodiments provide a first application process of applying and spreading the ink 22 on the ink discharge faces F of the upstream side from the stop position P of the first wipers 35a to 35c, and a second applying process of applying and spreading the ink 22 on the ink discharge faces F of the downstream side from the stop position P of the first wipers 35a to 35c. However, only the second applying process may be performed by moving the first wipers 35a to 35c from the stop position P to the downstream side only without providing the first applying process.
In this case, mist and paper dust adhered to the ink discharge faces F of the upstream side from the stop position P cannot be removed. However, mist and paper dust or similar adhered to the ink discharge face F of the downstream side from the stop position P can be removed more surely than before because the ink 22 is applied and spread over the whole ink discharge face F of the downstream side from the stop position P.
A conventionally-known other driving mechanism may be used for the driving mechanism of the carriage 31 (the first wipers 35a to 35c), which is constituted of the rack gear 38, the input gear 43, and the elevating mechanism 50. The number of the ink discharge nozzles 18 of the recording heads 17a to 17c and the interval between the nozzles or similar parameter may be set appropriately depending on the specifications of the ink-jet recording apparatus 100. In addition, the number of the recording heads is not specifically limited. For example, one, two, or four or more recording heads 17 for each of the line heads 11C to 11K may be located.
The disclosure may also be applied to an ink-jet recording apparatus for monochromatic printing having only any one of the line heads 11C to 11K. In that case, since one each of the recording heads 17a to 17c is provided, it is only necessary that the first wipers 35a to 35c, which correspond to the recording heads 17a to 17c, are secured to the carriage 31. Effects of the disclosure will be further illustrated by the following examples.
When performing the wiping operation with using the wiping mechanism 30 according to the first embodiment, the difference in spreading of the ink 22 is examined in cases for both stopping and not stopping the first wipers 35a to 35c at the stop positions P. A testing machine was prepared. The testing machine includes the carriage 31 that moves to the approaching or separating direction with respect to the ink discharge faces F of the recording heads 17a to 17c as well as reciprocating along the ink discharge faces F and attached rubber blades made of EPDM (Asker hardness 60, impact resilience about 60%) having a width of 30 mm, a height of 7 mm, and a thickness of 1.5 mm as used for the first wipers 35a to 35c.
The recording heads 17a to 17c includes dot forming units with a structure illustrated in
The ink 22 to be used is a water based ink having a composition composed of the items as described in Table 1. After agitating the respective components, the solution was pressure-filtrated by a filter of pore size of 5 μm to make the ink 22.
Spreading of the ink 22 on the ink discharge face F was assessed for a case where the first wipers 35a to 35c were stopped for a predetermined duration at the stop position P (Test example 1) and a case where the first wipers 35a to 35c were not stopped (comparison example). As illustrated in
As is obvious from Table 2, in comparison example where the first wipers 35a to 35c were not stopped at the stop positions P, the adhesion of the ink at the locations 2 and 3 that are facing the nozzle region R was confirmed. However, the adhesion of the ink was not observed at the location 1 that does not face the nozzle region R. On the other hand, in Test example 1 where the first wipers 35a to 35c were stopped at the stop positions P, adhesion of the ink was confirmed at all the locations 1 to 3.
When performing the wiping operation with using the wiping mechanism 30 according to the first embodiment, the relationship between the shape of the upper end faces of the first wipers 35a to 35c and spreading properties of ink were investigated. Using the first wipers 35a to 35c having the similar configuration of the Working Example 1, the time till the ink is filled with between the upper end faces of the first wipers 35a to 35c and the ink discharge faces F after discharging the ink was measured for the following examples: (1) a case where the upper end faces of the first wipers 35a to 35c are flat (Test example 2), (2) a case where rectangular shaped concave portions 60 as illustrated in
As is obvious from Table 3, it took five seconds to fill the ink in Test example 2 where the upper end faces of the first wipers 35a to 35c are flat, whereas it took three seconds and two seconds to fill the ink in Test example 3 and 4, respectively, which include the concave portions 60 on the upper end faces. These results confirmed that the time to fill the ink may be shortened by forming the concave portions 60 on the upper end faces of the first wipers 35a to 35c. In addition, the comparison of Test examples 3 and 4 confirmed that the tapered shape where the groove width is gradually widened from the side where the ink contacts are more preferable for the shape of the concave portions 60.
When performing the wiping operation with using the wiping mechanism 30 according to the first embodiment, a degree of wiping the mist adhered to the upstream side of the wiping direction from the stop position P was observed in the following cases: (1) a case where the first wipers 35a to 35c moved to the end edge of the downstream side of the wiping direction after moving the first wipers 35a to 35c from the stop position P to the end edge of the upstream side of the wiping direction while holding ink between the upper end faces of the first wipers 35a to 35c and the ink discharge faces F as illustrated in
As is obvious from Table 4, the remaining of mist in the upstream side of the wiping direction from the stop position P was not observed in Test example 5 where the first wipers 35a to 35c was moved to the end edge of the downstream side of the wiping direction after moving the first wipers 35a to 35c from the stop position P to the end edge of the upstream side of the wiping direction. On the other hand, the remaining of mist in the upstream side of the wiping direction from the stop position P was confirmed in Test example 6 where the first wipers 35a to 35c were moved from the stop position P to the end edge of the downstream side of the wiping direction. This results confirmed that the mist adhered to the upstream side of the nozzle region R in the wiping direction can also be effectively removed by moving the first wipers 35a to 35c to the end edge of the downstream side of the wiping direction after moving the first wipers 35a to 35c from the stop position P to the end edge of the upstream side of the wiping direction.
The disclosure is applicable to an ink-jet recording apparatus that performs recording by discharging ink from the recording head. Use of the disclosure ensures an ink-jet recording apparatus with a recovery mechanism that can remove the dried mist and foreign object such as paper dust adhered to the ink discharge face of the recording head more surely and effectively suppress poor ink discharge and reduction in sealability when mounting the cap.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
Number | Date | Country | Kind |
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2013-136605 | Jun 2013 | JP | national |