Abstract:
A nozzle wiping apparatus comprises an ink-absorbent sheet placed below the ink discard hole to collect the sucked ink discarded through the ink discard hole and an ink absorbent sheet winding mechanism to wind up the ink-absorbent sheet. The ink-absorbent sheet is kept in contact with a part of the nozzles after completion of the purging operation so the nozzles may be moved relative to the ink-absorbent sheet to thereby wipe ink deposited on the nozzles.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink purge apparatus, an ink purging method, a nozzle wiping apparatus and a wiping method in a printer using hot-melt ink. 
     2. Description of the Related Art 
     Examples of a method for purging a print head using hot-melt solid ink include: a method in which an ink chamber of the print head is pressurized to discharge ink from an orifice; and a method in which a suction unit is pressed against an orifice to suck ink from the orifice directly. As the ink chamber pressurizing method, a method in which waste ink is sucked by a sheet of wiping paper is employed in manufactured articles. On the other hand, as the orifice suction method, there is a method described in Japanese Patent Unexamined Publication No. Hei 4-111149. 
     In the orifice suction method, however, a surface of the orifice may be stained with ink when the ink is sucked from the orifice or ink may be spilled around the head when the ink is discarded. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in order to solve the above problems with the prior art, and therefore an object of the invention is to provide an ink purge apparatus of the suction type which is simplified in structure without using a motor and a solenoid, resulting in the reduction of the costs. 
     Another object of the present invention is to provide an ink purge apparatus which prevents the orifice surface from being stained with ink when the orifices are sucked and prevents the ink from being spilled around the head when the ink is discarded. 
     Still another object of the present invention is to provide an ink purging method in which an ink discarding process is simple. 
     Yet still another object of the present invention is to provide an apparatus having a simple configuration for wiping a nozzle surface, and a wiping method, particularly, to provide a method for preventing ink from being spilled around a head. 
     In order to achieve the above object,according to the present invention, there is provided an ink purge apparatus for use in a printer for discharging an ink which is located outside of a printing region of an ink jet head having a horizontally and vertically movable mechanism, in which when the ink received in an ink tank of said ink jet head is discharged, said ink jet head is moved out of the printing region, the ink received within the ink tank is sucked from a nozzle portion of the ink jet head and discharged to the external, said apparatus comprising: 
     an ink suction casing with an opening portion that comes in close contact with and covers the nozzle portion of the ink jet head when the ink jet head moves forward up to a given position; 
     a mechanism for moving the nozzle portion of the ink jet head forward and backward relatively with respect to said ink purge casing; 
     a suction pump connected to said ink suction casing; 
     an ink discard hole portion provided on the bottom of said ink suction casing for discharging the ink; 
     open/close means for said ink discard hole portion, said open/close means having a protrusion which is made of an elastic member and a tip of which protrudes from the opening surface of said ink suction casing when the tip is out of contact with the ink jet head, said open/close means closing said ink discarding hole while being pushed by said protrusion when the ink jet head moves forward toward said ink purge casing. 
     The ink purge apparatus may be designed such that the opening portion of said ink suction casing has an elastic seal member which is brought into close contact with the nozzle plate surface of said ink jet head, the elastic member of said open/close means is molded integrally with said seal member and has a valve portion located on an extension of said protrusion portion and below said ink discarding hole, and the value portion and the peripheral bottom portion of the ink discarding hole of said ink suction casing are inclined and face each other. 
     The ink purge apparatus may be designed such that said printer includes an easel to which an object to be printed is fixed and guides disposed on said easel for guiding the movement of the ink jet head horizontally and vertically, and said ink purge unit is disposed on an arbitrary end portion of said easel. 
     The ink purge apparatus may be designed such that the ink received within the ink tank of the ink jet head is a thermally meltable ink, and said ink purge unit includes a heat for melting the ink within said ink suction casing. 
     Also, according to the present invention, there is provided an ink purge method for use in a printer in which a thermally melted ink received within an ink tank of the ink jet head is sucked and discharged from a nozzle portion of an ink jet heat toward the exterior of the ink jet head by ink suction purge means, said method comprising the steps of: 
     providing on a bottom portion of an ink suction casing of said purge means an ink discard hole from which the sucked melted ink is discharged to the external; 
     disposing a suction ink sheet and a suction ink sheet winding-up means below the ink discard hole; and 
     discarding the ink sucked and collected by said purge means onto said suction ink sheet while the suction ink sheet is wound up by the winding-up means to discard the ink. 
     Further, according to the present invention, there is provided an nozzle wiping apparatus for use in a printer comprising an ink jet head constituted by an ink tank for reserving ink, a plurality of nozzles provided so as to discharge ink as liquid drops by an ink drop generating means, and a carriage for carrying these nozzles to an arbitrary position, an easel erected substantially vertically, a printing medium fixed onto said easel, a suction purge means disposed at an arbitrary end portion on said easel and in a position facing said nozzles, and a moving means for making said nozzles move forward or backward relative to said suction purge means, whereby printing is performed by moving horizontally and vertically relative to said easel, said nozzle wiping apparatus comprising: 
     a waste ink discard means for discarding ink sucked by said suction purge means; 
     an ink-absorbent sheet placed below said waste ink discard means; and 
     a winding-up means for winding said ink-absorbent sheet up; 
     wherein said ink-absorbent sheet is always brought in contact with a part of said nozzles during a purging operation. 
     The nozzle wiping apparatus may be designed such that said ink-absorbent sheet winding-up means comprises a driving roller, a driven roller, a pulley, a guide cover slidably engaged with opposite ends or one end of said pulley, and a spring having one end fixed to said guide cover and the other end fitted to one end of said pulley. 
     The nozzle wiping apparatus may be designed such that said ink-absorbent sheet winding-up means comprises a driving roller, a driven roller, a pulley, a guide base for rotatably mounting said pulley, said driving roller and said driven roller, a pivot for making said guide base rockable, and a spring laid between said easel and said guide base. 
     The nozzle wiping apparatus may be designed such that a part of said ink-absorbent sheet winding-up means is made rockable in linkage with said purging operation. 
     Also, in the above-described nozzle wiping apparatus of a printer, 
     a wiping method comprising the steps of: 
     moving said ink jet head resting in an arbitrary position of said easel to a position facing said suction purge means; 
     advancing said ink jet head toward said suction purge means to bring only said ink-absorbent sheet into contact with a part of a nozzle plate; 
     further advancing said ink jet head to bring said ink jet head into contact with said suction purge means to perform a purging operation; 
     retracting said ink jet head from said suction purge means while bringing said ink-absorbent sheet into contact with said nozzle plate after completion of said purging operation; and 
     moving said ink jet head downward while bringing said ink-absorbent sheet into contact with said nozzle plate to thereby wipe ink deposited on said nozzle plate. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view showing the purging operation of a printer in the present invention; 
     FIG. 2 is a sectional view showing the purging operation of the printer in the present invention; 
     FIG. 3 is a sectional view showing the purging operation of the printer in the present invention; 
     FIG. 4 is a sectional view showing the purging operation of the printer in the present invention; 
     FIG. 5 is a perspective view showing a part of the configuration of the ink-absorbent sheet winding-up means in the present invention; 
     FIG. 6 is a perspective view of the ink-absorbent sheet winding-up means as another example of the present invention; and 
     FIG. 7 is a perspective view showing the overall configuration of the printer in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Now, a description will be given in more detail of the preferred embodiments of the present invention with reference to the accompanying drawings. 
     The configuration of a printer  1  is shown in FIG.  7 . 
     A sheet of printing paper  3  is stuck onto a front surface of an easel  2  erected substantially vertically. An ink jet head  10 , which can move horizontally and vertically freely on a front surface of the sheet of printing paper  3 , is constituted by a carriage  5 , an ink tank  4  attached on an upper portion of the carriage  5 , and a nozzle plate  11  provided in front of the ink tank for jetting ink. Reference numeral  12  designates claw portions; and  14 , designates ink chambers. 
     A plurality of nozzles (not shown) are disposed in the nozzle plate  11  so as to eject ink droplets from a nozzle portion through ink droplet generating means (not shown), for example, a piezoelectric element in response to an image signal. 
     The reference numeral  6  designates a wire for pulling the ink jet head  10  through a scanning drive mechanism (not shown) horizontally, by which the ink jet head  10  moves horizontally while being guided by a guide  7 A. Reference numeral  9  denotes pulleys supported by the guide  7 A and a guide  7 B for holding the wire  6 . Reference numeral  8  designates a belt for moving the ink jet head vertically, and the belt drive allows the ink jet head  10  to move vertically while being guided by the guide  7 B. An end of the guide  7 A is attached to the belt  8 . 
     An ink purge unit  30  is disposed on an edge portion of the easel  2 , for example, on an upper corner of the easel  2 . Reference numeral  50  denotes an ink-absorbent sheet winding-up means; also referred to as an ink absorbent sheet winding mechanism and  53 , an ink-absorbent sheet. 
     FIGS. 1 to  4  are sectional views showing the positional relation between the ink jet head  10  and the ink purge unit  30 . FIG. 1 shows a before-purge state; FIG. 2 shows a purge state; FIG. 3 shows a state of ink ejection after purging; and FIG. 4 shows a nozzle-wiping state. 
     As shown in those drawings, the ink jet head  10  with the nozzle portion (nozzle plate  11 ) and the ink tank  4  is so designed as to move forward and backward with respect to the ink purge unit  30 . The forward and backward movement of the ink jet head  10  is executed on the carriage  5  in a state where the carriage  5  is left as it is as shown in FIG.  1 . 
     The ink purge unit  30  includes an ink suction casing  31  an opening portion  31 A of which is brought in close contact with and covers the nozzle portion when the ink jet head  10  moves forward up to a predetermined position facing the ink suction purge unit  30 . For example, the opening portion  31 A of the ink suction casing  31  has an elastic seal member  35  at its periphery, and the elastic seal member  35  comes in close contact with the nozzle plate surface  11  of the ink jet head  10 . 
     The ink suction casing  31  has a suction inlet  36  at its upper surface and is connected to a suction pump (vacuum pump)  38  through the suction inlet  36  and a hose  37 . A barrier portion  39  for shielding the suction inlet  36  from the opening portion  31 A is disposed within the ink suction casing  31  so as to be suspended from the upper side of the casing  31 , and the intervention of the barrier portion  39  prevents the suction ink from being sucked toward the suction inlet  36  side. On the bottom portion of the ink suction casing  31  are disposed an ink discarding hole  32  for exhausting the suction ink collected within the casing  31 , and open/close means  35   c  for the ink discarding hole  32 . The open/close means  35   c  also referred to as a resilient ink discharge hole closing structure, is made of an elastic member and basically structured as follows: That is, the open/close means  35   c  has a protrusion portion  35   b  that protrudes forwardly from the position of the opening surface  31 A of the ink casing  31  when the tip end of the protrusion portion  35   b  is out of contact with the ink jet head  10 . When the ink jet head  10  is forwarded toward the ink purge unit  30  side, the open/close means  35   c  closes the ink discarding hole  32  and closes the ink discarding hole  32  while being pushed through the protrusion portion  35   b  by the ink jet head  10  as shown in FIG.  2 . When the ink jet head  10  and the protrusion portion  35   b  are out of contact with each other, the open/close means  35   c  is apart from the ink discarding hole  32  due to an elastic restore force. The specific example of the open/close means  35   c  will be described below. 
     The open/close means  35   c  is formed of a valve portion  35   c  which is made of an elastic member and molded integrally with the seal member  35 . The valve portion  35   c  is shaped in an inclined plate and placed on an extension of the protrusion portion  35   b  and below the ink discarding hole  32 . The valve portion  35   c  is supported in a cantilever manner at a lower edge  35   a  of the seal portion  35  through a beam portion  35   d . The valve portion  35   c  is obliquely attached to the protrusion portion  35   b . An inclined surface  31   c  facing the valve portion  35   c  is formed on the peripheral bottom portion of the ink discarding hole  32  of the ink suction casing  31 . 
     That is, since the valve portion  35   c  and the ink suction casing  31  obliquely faces each other, when the protrusion portion  35  is pushed by the ink jet head  10 , the valve portion  35   c  abuts against the inclined surface  31   c  of the ink suction casing  31 , thereby closing the ink discarding hole  32 . 
     Since the ink employed in this embodiment is a thermally meltable solid ink, a heater for heating the ink (not shown) is provided on the ink jet heat  10  side, and another heater  33  of the same type is also provided on the ink purge unit  30  side. The latter heater  33  is stuck to the back surface of the ink suction casing to heat the ink suction casing  31 . 
     The elastic member of the seal member  35 , the protrusion portion  35   b , the valve portion  35   c , etc., is molded with silicone rubber which is heat-resistant and soft. Reference numeral  35   a  designates a contact surface with respect to the nozzle plate; and the above-mentioned protrusion portion  35   b  is placed so as to slightly protrude from the contact surface  35   a.    
     The ink sheet winding-up means  50  is disposed under the ink discarding hole  32  and includes a driving roller  51 , a driven roller  52 , and a pulley  54  disposed at a slight distance from the nozzle plate  11  so as to face the nozzle plate  11  before purging. The ink sheet  53  is set so as to be wound on the driven roller  52  and taken up on the driving roller  51  through the pulley  54 . Further, the ink discarding hole  32  of the ink suction casing  31  is disposed above the ink sheet  53  between the pulley  54  and the driving roller  51 . 
     The operation will be described below. 
     When ink jetting from the nozzles is abnormal at printing time or at non-printing time, the ink jet head  10  on the easel is moved to a position facing the suction purge means  30  (FIG.  1 ). In this case, the ink-absorbent sheet  53  has not come into contact with the nozzle surface  11  yet. 
     Then, the ink tank  4  and the nozzle plate  11  are advanced toward the suction purge means  30  by a moving means (not shown). At the same time when the nozzle plate  11  comes into contact with the contact surface  35   a  of the elastic body  35 , the nozzle plate  11  presses the protrusion portion  35   b  of the elastic body. As a result, the valve portion  35   c  on the extension of the protrusion portion  35   b  can block the ink discarding hole  32  provided in the lower portion of the ink casing  31  (FIG.  2 ). 
     Further, in this configuration, before the nozzle plate  11  is advanced and brought into contact with the suction purge means  30 , the lower portion of the nozzle plate  11  comes into contact with the ink-absorbent sheet  53 . When the nozzle plate  11  is further advanced so as to come into contact with the suction purge means  30 , the pulley  54  which is a part of the ink-absorbent sheet winding-up means  50  is pushed by the nozzle plate so as to move to the right in the drawing. By moving only the pulley for the ink sheet in the aforementioned manner, the movable portion can be suppressed to be in a small range compared with the case where the ink sheet winding-up means is rocked as a whole. Further, by setting the ink sheet winding-up direction to be substantially perpendicular to external force at pressing time, the contact pressure between the head and the ink sheet can be prevented from being reduced greatly when the ink sheet is wound up. 
     When the suction purge pump  38  is driven in the condition that the ink discarding hole  32  is blocked by the valve portion  35   c , that is, in the condition of FIG. 2, ink is sucked out from the nozzle plate  11  and then reserved in the inside of the ink casing  31 . 
     Then, the ink tank  4  and the nozzle plate  11  are retracted by the moving means. When the nozzle plate  11  is retracted to a position where the nozzle plate  11  is not in contact with the protrusion portion  35   b  of the elastic body, the state of the valve portion  35   c  blocking the ink discarding hole  32  is returned to its original state by restoring force. As a result, waste ink reserved in the inside of the ink casing  31  can be discharged to the ink sheet  53  through the ink discarding hole  32  (FIG.  3 ). If the driving roller  51  is operated in synchronism with the timing of discarding waste ink in this case, waste ink on the ink sheet can be rolled up with a substantially uniform thickness. Incidentally, also in this case, the ink-absorbent sheet  53  is placed so as to be in contact with the nozzle plate  11 . 
     Further, by moving the ink jet head  10  downward as shown in FIG. 4, ink deposited on the nozzle plate  11  can be wiped. If the ink-absorbent sheet  53  is wound up in linkage with the movement of the ink jet head in this case, nozzle wiping can be performed more efficiently. 
     FIG. 5 shows the pulley portion  54  of the ink-absorbent sheet winding-up means for making the aforementioned operation possible. 
     In the drawing, slots  57  for supporting opposite ends of the pulley  54  are provided in the guide cover  56 . Further, springs  58  each having one end engaged with the pulley  54  and the other, opposite end fitted to the guide cover are set in the slots  57  respectively. Accordingly, when the ink jet head  10  (not shown) located in the left of the pulley  54  in the drawing is pressed to the right in the drawing in connection with the purging operation, the pulley  54  can move right along the slots  57 . 
     As described above, in this configuration, only the pulley  54  is moved together with the nozzle plate  11 , so that a series of purging operation can be performed. 
     FIG. 6 shows another configuration than FIG.  5 . In FIG. 6, the whole of the ink-absorbent sheet winding-up means  50  is operated so that the purging operation can be performed. 
     In the drawing, the reference numeral  61  designates a driving roller;  62 , a driven roller;  64 , a pulley;  66 , a guide base for supporting the driving roller, the driven roller and the pulley;  67 , a pivot for rocking the guide base; and  68 , a spring for fitting the guide base to a part  2   a  of the easel. 
     The ink jet head  10  (not shown) is disposed in the left of the pulley  64  in the drawing. When the ink jet head  10  moves right, the nozzle plate  11  presses the pulley  64  through the ink-absorbent sheet  53 . As a result, the whole of the ink-absorbent sheet winding-up means  50  rotates around the pivot  67  (operation of FIG.  2 ). If the nozzle plate is then moved left in the drawing, the state of the ink-absorbent sheet winding-up means  50  can be returned to its original state by restoring force of the spring  68 . 
     As described above, according to the present invention, the nozzle surface could be wiped by a simple configuration. Further, ink could be prevented from being spilled around the head when a series of purging operation was carried out.