Patent Publication Number: US-9849678-B2

Title: Liquid discharger including a head, a cap, a belt, and a belt cleaner

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese patent application numbers 2015-199315, filed on Oct. 7, 2015, the entire contents of which are incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a liquid discharger, and in particular relates to a liquid discharger including a head to discharge liquid droplets. 
     Description of the Related Art 
     As an image forming apparatus such as a printer, a facsimile machine, a copier, a plotter, and a multifunction apparatus combining several of the capabilities of the above devices, a liquid discharger, such as an inkjet recording apparatus, using a liquid discharging recording method employing a recording head that discharges ink droplet is known. 
     Such a liquid discharger has a head that discharges liquid droplet from nozzles. A discharge failure may occur for several reasons. For example, a solvent in liquid evaporates from the nozzles which increases the viscosity of liquid in the nozzles. A discharge failure also occurs due to the solidification of the liquid in the nozzles and by attachment of dust on the nozzles. 
     A cap that covers the nozzle face is used for cleaning the nozzles and retaining moisture in the nozzle. Also, a cap cleaning apparatus, such as cap stamper, is used for cleaning the cap. 
     The parts of the cap cleaner, such as stamper, which contacts the cap are usually arranged to face the cap. Therefore, the parts of the cap cleaner are difficult to be replaced. Furthermore, the parts of the cap cleaner which contact the cap not only absorb the dirt of the cap but also the ink inside the cap. Thus it is necessary to replace the cap cleaner to clean the cap. 
     It is known in Japanese patent publication numbers 2011-25621 to use a wiper cleaner made of absorbing material that cleans the nozzle face of a print head, a wiper, and the cap. The wiper cleaner has a belt wound around a supply roller and winding roller. The belt is conveyed so that the unused part of the cap cleaner contacts and cleans the nozzle face and the wiper. 
     However, this wiper cleaner has to be replaced after using it because the wiper cleaner absorbs ink and waste liquid during the cleaning process. To replace the wiper cleaner, it is necessary to wind the roller while the wiper cleaner faces the nozzle face, and this increases working process. Furthermore, in order to keep the recording performance of the image forming apparatus for a long time, it is necessary to increase the winding number of the wiper cleaner, and this further increases the difficulty of replacing the wiper cleaner. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides an improved liquid discharger capable of cleaning a cap and cap cleaner. The liquid discharger according to preferred embodiments of the present invention includes a head to discharge liquid droplets; a cap to cover a nozzle face of the head; and a cap mover to move the cap to a capping position at which the cap faces the nozzle face of the head or to move the cap to an evacuation position at which the cap does not face the nozzle face of the head. Further, there is a belt arranged to face the cap at the evacuation position, the belt having a width and length enough to cover whole area of a rim of the cap. Additionally, there is a conveyer to drive the belt and a belt cleaner arranged to face the belt to clean the belt. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a liquid discharger according to a first embodiment of the present invention; 
         FIG. 2  is a schematic plan view of the liquid discharger; 
         FIGS. 3A and 3B  are a schematic view illustrating a main part of the liquid discharger according to the first embodiment of the present invention; 
         FIG. 4  is a schematic plan view of the main part of the liquid discharger viewed from the direction of arrow A in  FIG. 3B ; 
         FIG. 5  is a schematic view illustrating a main part of a liquid discharger according to a second embodiment of the present invention; 
         FIG. 6  is a schematic view illustrating a main part of a liquid discharger according to a third embodiment of the present invention; 
         FIG. 7  is a schematic view illustrating a main part of a liquid discharger according to a fourth embodiment of the present invention; 
         FIG. 8  is a schematic view illustrating a main part of a liquid discharger according to a fifth embodiment of the present invention; 
         FIG. 9  is a schematic view illustrating a main part of a liquid discharger according to a sixth embodiment of the present invention; and 
         FIGS. 10A and 10B  are schematic views illustrating a main part of a liquid discharger according to a seventh embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Hereinafter, preferred embodiments of the present invention will now be described with reference to accompanying drawings. 
     The First Embodiment 
       FIG. 1  is a schematic view illustrating a liquid discharger including a head to discharge liquid droplet and form an image on a recording medium. As shown in  FIG. 1 , the liquid discharger  100  has a supplier  10 , a pre-processer  20 , a dryer  30 , an image former  40 , a post-processer  50 , a winder  60 , a liquid holder and supplier  70 , a head maintainer  80 , and controller  90 . The controller  90  is connected to one or more of the elements of  FIG. 1 . The controller may be implemented using a programmed processor and/or special purpose circuitry. 
     A roll sheet Md as a recording medium is a continuous sheet, which is rolled and has a perforation, at which the roll sheet can be easily cut, formed in predetermined distances. 
     The supplier  10  supplies the roll sheet to the pre-processor  20 . The pre-processor  20  pre-processes a surface of the supplied roll sheet Md and sends the roll sheet Md to the dryer  30 . The dryer  30  dries the surface of the roll sheet Md and sends it to the image former  40 . 
     The image former  40  forms images on the recording medium. The head of the image former  40  discharges liquid, called ink hereinafter, on the surface of the roll sheet Md, which is pre-processed and dried, to form images. 
     The liquid holder and supplier  70  stirs the liquid to unify the concentration of liquid and supplies liquid to the head of the image former  10 . 
     The image formed roll sheet Md is sent to the post-processor  50 . Post-processor  50  post-processes the image formed roll sheet Md and sends it to the winder  60 . The winder  60  winds the roll sheet Md. The controller  90  controls the series of processes explained above. 
     In this patent specification, “sheet” is not limited to the paper material, but also includes an OHP sheet, fabrics, boards, film, metallic sheet, etc., on which ink droplets or other liquid are deposited. The term “sheet” is a collective term for a recorded medium, recording medium, recording sheet, and the like. The term “sheet” is not limited to the roll sheet, it can be cut sheet, ordinary sheet, cardboard, thin-paper, and fine paper. 
       FIG. 2  is a schematic plan view of the liquid discharger. As shown in  FIG. 2 , the image former  40  has four head units  40 K,  40 C,  40 M, and  40 Y corresponding to black, cyan, magenta, and yellow ink arranged in parallel along a convey direction Xm of the roll sheet Md shown by an arrow in  FIG. 2 . Each of the head units  40 K,  40 C,  40 M, and  40 Y has a plurality of heads that are arranged in a direction perpendicular to the convey direction Xm to cover whole width of the roll sheet. For example, the head unit  40 K has four heads  40 K- 1 ,  40 K- 2 ,  40 K- 3 , and  40 K- 4 . The head unit  40 K discharges black ink. The head unit  40 C discharges cyan ink. The head unit  40 M discharges magenta ink. The head unit  40 Y discharges yellow ink. The four head units  40 K,  40 C,  40 M, and  40 Y are arranged in this order along a convey direction Xm of the roll sheet Md shown by an arrow in  FIG. 2 . However the arrangement of each head units  40 K,  40 C,  40 M, and  40 Y can be different. Furthermore, the image former  40  can have a head unit that discharges green ink, red ink, light cyan, and ink of any other color. The image former  40  can have head units of a single color, such as black. 
     Here, the four heads  40 K- 1 ,  40 K- 2 ,  40 K- 3 , and  40 K- 4  of the head unit  40 K are arranged in a staggered manner in a direction perpendicular to the convey direction Xm of the roll sheet Md. Thus, the head unit  40 K can form a black (K) image all over the image forming region (printing region) of the roll sheet Md. The structures of other head units  40 C,  40 M, and  40 Y are same as the head unit  40 K, if desired. 
       FIGS. 3A and 3B  are schematic views illustrating a main part of the liquid discharger according to the first embodiment of the present invention. The liquid discharger  1  has a plurality of heads  101  to discharge liquid droplets, caps  102  to cover the nozzle face of the heads  101 , and cap mover to move the caps  102  to predetermined positions. Furthermore, the liquid discharger  1  has a belt  110  to remove the objects attached on the caps  102 , a conveyer  111  to drive the belt  110 , and a belt cleaner  112  to clean the belt  110  by removing objects attached to the belt  110 . 
     The cap mover  103  moves the caps  102  to a capping position  105  (See  FIG. 3A ) at which the caps  102  faces the nozzle face of the head  101  or moves the caps  102  to an evacuation position  106  (See  FIG. 3B ) at which the caps  102  does not face the nozzle face of the head  101  along the convey direction Xm of the roll sheet Md. The cap mover  103  also has a mechanism to move the caps  102  vertically. 
     The cap mover  103  has a cap holder  103   a  to hold the caps  102 . The cap mover  103  is moved in a vertical direction by cams  606   a  and  606   b,  a cam base  608 , and a cam motor  610  at the capping position  105 . Further, the cap mover  103  is moved in a vertical direction by cams  600   a  and  600   b,  a cam base  602 , and a cam motor  604  at the evacuation position  106 . The cap holder  103   a  is connected to the belt  620 , and the cap holder  103   a  moves together with the movement of the belt  620 . The belt  620  has a drive roller  614  connected to a motor  618  and driven roller  612 . The belt  620  is wound around the drive roller  614  and the driven roller  612 . The belt  620  moves by the rotation of the drive roller  614  and the driven roller  612 . 
     The cams  606   a  and  606   b,  a cam base  608 , and a cam motor  610  are disposed inside the belt  620  and fixed to the apparatus body at the capping position  105 . The cams  600   a  and  600   b,  a cam base  602 , and a cam motor  604  are disposed inside the belt  620  and fixed to the apparatus body at the evacuation position  106 . The cam motor  610  rotates the cams  606   a  and  606   b  to move the cap holder  103   a  upward and downward when the cap holder is positioned at the capping position  105  as shown in  FIG. 3A . The cam motor  604  rotates the cams  600   a  and  60  to move the cap holder  103   a  upward and downward when the cap holder  103   a  is positioned at the evacuation position  106  as shown in  FIG. 3B . The cams are connected to their corresponding motor by gears, for example. 
     When the caps  102  are located at the cap position  105 , the cap mover  103  elevates the caps  102  and pushes each of the rims of the caps  102  against the nozzle face of the heads  101  to protect and retain the moisture of the nozzle face of the heads  101 . On the other hand, when the heads  101  discharge liquid, the cap mover  103  moves the caps  102  to the evacuation position  106  at which the caps  102  do not face and cover the nozzle face of the heads  101 . 
     The conveyer  111  is provided above the evacuation position  106 , and the conveyer  111  drives the belt  110  when the rims of the caps  102  contact the belt  110  to clean the caps  102 . The belt cleaner  112  is arranged above the belt  110  and conveyer  111  to face the belt to clean the belt  110 . 
       FIG. 4  is a schematic plan view of the main part of the liquid discharger  1  viewed from the direction of arrow A in  FIG. 3B . As shown in  FIG. 4 , the conveyer  111  conveys the belt  110  laterally (in the direction shown by an arrow B) in the direction perpendicular to the convey direction Xm of the roll sheet Md. The belt  110  has a width and length sufficient to cover the whole area of the rims of the caps  102 . The belt  110  is made of elastic and water-resistant material. The belt  110  has a function of removing the dirt or object attached on the rims of the caps  102 . 
     The belt cleaner  112  is arranged above the belt  110  to face the belt  110 . The belt cleaner  112  has a brush or air suction mechanism to remove the dirt and other objects attached to the belt  110  to clean the belt  110 . The belt cleaner  112  is removable from the liquid discharger  1 , and the belt cleaner  112  can be set on the liquid discharger  1  again after disposing the object attached on the belt cleaner  112 . Also, only the object attached on the belt cleaner  112  can be removed separately from the belt cleaner  112 . 
     The cleaning process of the caps  102  of the liquid discharger  1  constructed as above will be explained below. 
     As shown in  FIG. 3B , the cap mover  103  moves the caps  102  from the capping position  105  to the evacuation position  106  by driving a belt motor  618  and moving the belt  620 . Next, as shown in  FIG. 4 , the cap mover  103  moves the caps  102  upward so that the rims of the caps  102  contact belt  110  at the evacuation position  106  by driving the cam motor  604  and rotating the cams  600   a  to move the cap holder  103   a  upward. At this time, the belt  110  is not driven and not moving. The belt  110  can thereby move the objects attached on the rim of the caps  102  to the belt  110 . 
     Next, the cap mover  103  moves caps  102  down to separate the caps  102  from the belt  110  by driving the cam motor  604  and rotating the cams  600   a  to move the cap holder  103   a  downward. When the caps  102  are separated from the belt  110 , conveyer  111  conveys the belt  110  so that a part of the belt  110 , on which the object is attached, is conveyed to the position where the belt cleaner  112  is provided. Then, the belt cleaner  112  cleans the belt  110  by means of a brush or air suction that removes objects from the belt  110 . The objects removed from the belt  110  are stored inside the belt cleaner  112 , and the objects can be removed from the belt cleaner  112  by detaching the belt cleaner  112  from the liquid discharger  1 . 
     In this way, the belt  110  is cleaned by the belt cleaner  112 , so that it is not necessary to replace the belt  110  for a long time. Also, the objects removed from the belt  110  can be removed by replacing or detaching the belt cleaner  112  from the liquid discharger  1 . Therefore, the present embodiment makes the process of cleaning the caps  102  easy, and maintaining the discharge function of the heads  101  easy. 
     As a preferred construction of the present embodiment of the liquid discharger surface of the belt  110  that contacts the caps  102  may have a finely woven mesh. By a capillary phenomenon generated by the finely woven mesh-like shape, the belt  110  can effectively remove and clean the liquid-like objects and solid objects attached to the rim of the caps  102 . 
     Furthermore, removing the object attached inside the belt cleaner  112  can be done during the operation of liquid charger  1 . 
     The Second Embodiment 
       FIG. 5  is a schematic view illustrating a main part of a liquid discharger according to a second embodiment of the present invention. In  FIG. 5 , the same code used in  FIG. 4  are applied to the elements that are the same as in  FIG. 4 , and the detailed explanation of which will be omitted. 
     As shown in  FIG. 5 , the liquid discharger  1  of the present embodiment uses the belt  110  to keep the moisture inside the caps  102 . That is, when the caps  102  are located at the evacuation position  106  as shown in  FIG. 3B , the cap mover  103  moves the caps  102  upward and makes the rim of the caps  102  contact the belt  110 . 
     Thereby, even during the liquid discharger  1  discharging liquid from the nozzle of the heads  102 , the belt  110  can protect the inside of the caps  102  from the outside environment. Thus, it is possible to protect and to keep the moisture of the nozzle face of the heads  101  in a highly humid condition. 
     It is preferable that the conveyer  111  does not drive and move the belt  110  when the caps  102  contacts the belt  110 . Then, it is possible to reduce abrasion of the contact part between the caps  102  and the belt  110  by avoiding the caps  102  from contacting with belt  110  during the conveying process. However, it is possible for the belt  110  to move relative to the caps  102  during the cleaning process. 
     The Third Embodiment 
       FIG. 6  is a schematic view illustrating a main part of a liquid discharger according to a third embodiment of the present invention. In  FIG. 6 , the same reference numerals used in  FIG. 4  are applied to the elements that are the same as in  FIG. 4 , and the detailed explanation of which will be omitted. 
     As shown in  FIG. 6 , the liquid discharger  1  of the present embodiment further comprises a tensioner  113  to adjust a tension applied to the belt  110 . That is, after the tensioner  113  adjusts the tension applied on the belt  110  properly, the caps  102  contact the belt  110 . Because the belt  110  can uniformly contact the caps  102 , it is possible to remove the object attached on the rim of the caps  102  effectively. 
       FIG. 7  is a schematic view illustrating a main part of a liquid discharger according to a fourth embodiment of the present invention. In  FIG. 7 , the same reference numerals used in  FIG. 4  are applied to the elements that are the same as in  FIG. 4 , and the detailed explanation of which will be omitted. 
     As shown in  FIG. 7 , the liquid discharger  1  of the present embodiment further comprises a pressurizing plate  114  that applies pressure on the belt  110  against the caps  102  from the back of the belt  110 . That is, when the belt  110  contacts caps the  102 , the pressurizing plate  114  applies additional pressure on the belt  110  against the caps  102 . Because the belt  110  can uniformly contact the caps  102 , it is possible to remove the objects attached on the rim of the caps  102  effectively. 
     The Fifth Embodiment 
       FIG. 8  is a schematic view illustrating a main part of a liquid discharger according to a fifth embodiment of the present invention. In  FIG. 8 , the same reference numerals used in  FIG. 4  are applied to the elements that are the same as in  FIG. 4 , and the detailed explanation of which will be omitted. 
     As shown in  FIG. 8 , the liquid discharger  1  of the present embodiment further comprises an ejector  115  to eject cleaning liquid on the belt  110 , and the ejector  115  disposed behind a position where an object attached on the belt  110  arrives at the belt cleaner  112 . That is, after the ejector  115  ejects cleaning liquid on the object attached on the belt  110 , the belt cleaner  112  cleans the belt  110 . Because the belt cleaner  112  cleans the belt  110  after the object attached on the belt  110  is floating on or loosened from the belt  110  by the cleaning liquid, it is possible to remove the objects attached to the belt  110  effectively by the belt cleaner  112 . 
     As cleaning liquid, water may be used. Also, the cleaning liquid may contain, if desired, a water-soluble organic solvent and a surfactant. The surfactant is used for reducing the surface tension of the ink to easily penetrate into a recording medium, or controlling the behavior of the dynamic surface tension. The water-soluble organic solvent is appropriately selected depending on the intended purpose without any limitation, and examples thereof include: 1,3-butanediol, diethylene glycol, triethylene glycol, and glycerin, which prevent jetting failures due to evaporation of moisture. 
     The Sixth Embodiment 
       FIG. 9  is a schematic view illustrating as main part of a liquid discharger according to a sixth embodiment of the present invention. In  FIG. 9 , the same reference numerals used in  FIG. 4  are applied to the elements that are the same as in  FIG. 4 , and the detailed explanation of which will be omitted. 
     As shown in  FIG. 9 , the liquid discharger  1  of the present embodiment further comprises a charger  117  to charge the belt  110  and a discharger  116  to discharge electricity on the belt  110 . Here, “discharge” means to electrically neutralize a charged object. The charger  117  is provided on the upstream side of the position where the belt  112  faces and contacts the caps  102 . In  FIG. 9 , there are plurality of caps  102 , and the charger  117  is provided on the upstream side of the cap  102 , which is located most upstream side in the belt convey direction B. In  FIG. 9 , the charger  117  faces the conveyer  111 . The discharger  116  is provided on the upstream side of the belt cleaner  112  in the belt convey direction B. 
     The charger  117  has a power source  117   a  and a charge roller  117   b  connected to the power source  117   a.  The power source  117   a  supplies AC voltage to the charge roller  117   b  to attract the object attached on the caps  102 . The charge roller  117   b  applies AC voltage on the belt  110 . The discharger is connected to the earth to release the electricity applied on the belt  110 . The power source  117   a  may supply direct voltage to the charge roller  117   b.    
     After the charger  116  charges the belt  112 , the caps  102  contacts the belt  112  so that the belt removes the object attached on the caps  102 . Further, after the discharger  117  discharges electricity on the belt  110 , the belt cleaner  112  cleans the belt  110 . Thereby the objects attached to the belt  110  can be effectively removed from the belt  110 . 
     The Seventh Embodiment 
       FIGS. 10A and 10B  are schematic views illustrating a main part of a liquid discharger  1  according to a seventh embodiment of the present invention. In  FIGS. 10A and 10B , the same reference numerals used in  FIGS. 3A and 3B  are applied to the elements that are the same as in  FIGS. 3A and 3B , and the detailed explanation of which will be omitted. 
     As shown in  FIGS. 10A and 10B , the liquid discharger  1  of the present embodiment further has a conveyer  111   a  that not only drives and convey the belt  110 , but also moves the belt  110  upward and downward vertically. Furthermore, the heads  101   a  move upward and downward vertically, so that the caps  102  can cover the nozzle face of the heads  101   a.  The cap mover  103   a  moves the caps  102  along the convey direction Xm of the roll sheet Md. 
     The belt  110  has a cam  624  and a motor  626  to rotate the cam  624 . The controller  500  drives the motor  626  and rotates the cam  624 . The cam  624  contacts a shaft  622  of the conveyer  111   a  and moves the belt  110  upward or downward by the rotation of the cam  624 . Further, the heads  101   a  have a cam  630  and a motor  632  to rotate the cam  630 . The controller  500  drives the motor  632  and rotates the cam  630 . The cam  630  contacts a holder  628  of the heads  101   a  and moves the heads  101   a  upward or downward by the rotation of the cam  630 . 
     Using the configuration shown in  FIGS. 10A and 10B , it is possible to cover the nozzle faces of the heads  101   a  by the caps  102 . Furthermore, the conveyer  111   a  moves the belt  110  upward or downward vertically, thus the conveyer  111   a  can move the belt  110  to contact with or separate from the caps  102 . Therefore, the belt  110  can remove the object attached on the rim of the caps  102  to clean the caps  102 . 
     Furthermore, the second embodiment shown in  FIG. 5 , the third embodiment shown in  FIG. 6 , and the fourth embodiment shown in  FIG. 7 , the fifth embodiment shown in  FIG. 8 , and the sixth embodiment shown in  FIG. 8  may have the conveyer  111   a  that moves the belt  110  upward or downward vertically to contact or separate the belt  110  with the caps  102 . 
     The liquid discharger  1  may have both of the conveyer  111   a  that moves the belt  110  upward or downward vertically, and a cap mover that moves the caps  102  upward or downward vertically. 
     The liquid discharger  1  may have a controller  90  to keep the caps  102  and the belt  10  to contact with each other during the caps  102  being positioned at the evacuation position  106 . 
     The term “liquid discharger” means a device for discharge liquid by transmitting, ejecting, discharging, or impacting liquid droplets towards a surface such as media including paper, thread, fiber, fabric, leather, metals, plastics, glass, wood, ceramics and the like. 
     The “liquid” includes ink, but it is not limited to so-called ink, but it is used as an inclusive term for every liquid such as recording liquid, fixing liquid, and aqueous fluid to be used for image formation, which further includes, for example, DNA samples, registration and pattern materials and resins. 
     Further, the liquid discharger includes, otherwise limited in particular, any of a serial-type liquid discharger that scans the head during discharging liquid, and a line-type liquid discharger having a single head or plurality of heads arranged to cover the whole width of the roll-sheet and does not move the head during discharging liquid. Further, the invention includes alternative embodiments which are combinations of any or all of the features disclosed herein. 
     Additional modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.