Patent Publication Number: US-6220314-B1

Title: Waste-ink collecting apparatus

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a waste-ink collecting apparatus for an ink-jet printer, and, more particularly, to a waste-ink collecting apparatus which collects waste inks to be discharged at the time of maintenance of a recording head that ejects ink. 
     An ordinary ink-jet printer has a recording head so arranged as to face a recording medium which is to be fed in a predetermined direction. The recording head has a plurality of nozzles aligned in a direction approximately perpendicular to the feeding direction of the recording medium. In printing characters or an image on a recording medium, the recording medium is fed at a constant speed in a predetermined direction and ink is selectively ejected from the nozzles of the recording head. 
     To accomplish high-resolution printing, the nozzles of a recording head are designed to have a very small diameter and are arranged close to one another at a high density. As the nozzles are made narrow, the nozzles are likely to clog with the passage of time. To prevent clogging of the nozzles of the recording head, the nozzles should be cleaned regularly. 
     In cleaning the nozzles of the recording head, the recording head is driven to discharge foreign matters and gases from the nozzles with a recording medium unfed. At this time, the waste inks discharged from the nozzles is retained in a predetermined ink retainer. 
     An air-liquid separation chamber is connected to the ink retainer via a waste-ink tube. Connected to the air-liquid separation chamber is a suction pump which generates negative pressure in the chamber. A filter for trapping an ink mist contained in the discharged gas is provided on the air-discharge side of the suction pump. 
     When the suction pump is driven, negative pressure is generated in the air-liquid separation chamber, causing the waste inks in the ink retainer to flow into the air-liquid separation chamber via the waste-ink tube. The ink mist discharged via the suction pump is trapped by the filter. 
     The waste inks that have flown into the air-liquid separation chamber are collected in a waste-ink collection tank by a liquid-discharge pump connected to the air-liquid separation chamber. When the waste-ink collection tank becomes full of waste ink, it is separated from a liquid-discharge tube led out from the liquid-discharge side of the liquid-discharge pump and removed. 
     With the above conventional structure, if a filter with a rough mesh is selected in consideration of the air discharging performance of the suction pump, it is not possible to completely trap the ink mist contained in the discharged air so that a waste ink is discharged in the air. 
     As the waste-ink collection tank is designed to be removable after it is separated from the liquid-discharge tube, waste inks are likely to leak from the portion where the waste-ink collection tank is connected to the liquid-discharge tube. The conventional structure therefore requires a collection mechanism for collecting the waste inks that have leaked from the connected portion between the tank and the tube. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a waste-ink collecting apparatus which is simple in structure and which can prevent waste inks from staining the interior of a printer. 
     To achieve the above object, a waste-ink collecting apparatus according to one aspect of this invention comprises a collection box for collecting waste ink; a holding case for retaining the collection box in a detachable manner; a nozzle unit attached to the holding case, having nozzles for disposing waste ink to the collection box and movable between a waste position where the waste inks are disposable through the nozzles and a standby position where the waste inks are not disposable; and an urging member for urging the nozzle unit to the standby position, whereby installing the collection box in the holding case moves the nozzle unit to the waste position an urging force of the urging member and removing the collection box from the holding case causes the urging member to move the nozzle unit to the standby position. 
     According to another aspect of this invention, there is provided a waste-ink collecting apparatus which comprises a collection box retaining an absorptive member for absorbing and holding waste inks; a holding case for retaining the collection box in a detachable manner; a nozzle unit rotatably attached to the holding case, having nozzles for disposing waste inks to the absorptive member and rotatable between a waste position where the waste inks are disposable through the nozzles and a standby position where the waste inks are not disposable; first urging member, provided between the holding case and the nozzle unit, for urging the nozzle unit to the standby position; a housing accommodating the holding case in an elevatable manner between a predetermined upper end position and a predetermined lower end position; second urging member, provided between the housing and the holding case, for urging the holding case to the upper end position, whereby installing the collection box in the holding case rotates the nozzle unit to the waste position against an urging force of the first urging means and removing the collection box from the holding case causes the first urging member to rotate the nozzle unit to the standby position, and wherein the holding case is elevated downward to the lower end position by a dead weight thereof against an urging force of the second urging means when the absorptive member absorbs a predetermined amount of waste inks. 
     Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
     The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention. 
     FIG. 1 is an exploded perspective view illustrating a waste-ink collecting apparatus according to one embodiment of this invention disassembled into a plurality of constituting elements; 
     FIG. 2 is a perspective view showing a cleaning mechanism of a recording head in which the waste-ink collecting apparatus in FIG. 1 is installed; 
     FIG. 3 is a perspective view showing the individual constituting elements assembled together; 
     FIG. 4 is a perspective view depicting a holding case in which a nozzle unit of the waste-ink collecting apparatus in FIG. 1 is installed and a collection box; 
     FIG. 5 is a diagram view showing the collection box to be installed in the holding case; 
     FIG. 6 is a diagram showing the collection box installed in the holding case and waste inks being collected; 
     FIG. 7 is a diagram depicting the collection box full of waste ink; and 
     FIG. 8 is a schematic diagram exemplifying the structure of this invention as adapted to an ink-jet printer which uses four color inks. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A preferred embodiment of the present invention will now be described with reference to the accompanying drawings. 
     FIG. 1 presents an exploded perspective view of a waste-ink collecting apparatus (hereinafter simply called “collecting apparatus”)  1  according to one embodiment of this invention. 
     A collecting apparatus  1  comprises a collection box  30  retaining an absorptive member  34  which absorbs waste inks, a holding case  40  for detachably holding this collection box  30 , a nozzle unit  50  which is rotatably installed in the holding case  40  and a housing  60  in which the holding case  40  to which the collection box  30  and the nozzle unit  50  are attached is accommodated in a rotatable manner. An a spring  72  as first urging member for urging the nozzle unit  50  is intervened between the holding case  40  and the nozzle unit  50 . A spring  74  as second urging member for urging the holding case  40  is intervened between the housing  60  and the holding case  40 . 
     Before going into the discussion of the detailed structure of the collecting apparatus  1  in FIG. 1, a cleaning mechanism  100  of an ink-jet printer to which this invention is applied will be described referring to FIG.  2 . This cleaning mechanism  100  includes the collecting apparatus  1  of this invention, and regularly cleans a recording head  10  of the ink-jet printer. 
     The recording head  10  has a plurality of ink chambers  11  which retain inks of predetermined colors supplied from unillustrated ink tanks. Each ink chamber  11  has multiple nozzles  12  protruding toward an unillustrated recording medium which is fed in the sheet feeding direction (sub scan direction) below the recording head  10 . The multiple nozzles  12 , e.g., about 2000 nozzles, are aligned along in the main scan direction (right and left direction in the figure) perpendicular to a feeding direction of the recording medium. When this recording head  10  is driven, the inks in the individual ink chambers  11  are selectively ejected from the multiple nozzles  12 , thus forming a predetermined image on the recording medium that is fed at a constant velocity. 
     The cleaning mechanism  100  has a slide rail  13  extending under the recording head  10  in the main scan direction, and a slider  14  attached to be movable in the main scan direction along this rail  13 . Attached to the upper portion of the slider  14  is a blade  15  which slides in contact with the distal ends of the multiple nozzles  12 . Provided below the slide rail  13  are a maintenance stage  16  which receives waste inks discharged from the multiple nozzles  12  and a reception tank  17  which collects the waste inks received by the maintenance stage  16 . 
     In cleaning the recording head  10 , first, with the recording medium unfed, the recording head  10  is driven to eject the inks from all the nozzles  12  to discharge foreign matters and gases remaining in the nozzles  12 . At this time, the waste inks containing the foreign matters and gases discharged from the nozzles  12  are collected in the reception tank  17  via the maintenance stage  16 . Then, the slider  14  is slid along the slide rail  13 , causing the blade  15  to slide in contact with the distal ends of the nozzles  12 . At this time, the waste inks collected by the blade  15  are likewise collected in the reception tank  17 . The waste inks collected in the reception tank  17  in this manner contain air. 
     An air-liquid separation chamber  19  is connected via a suction tube  18  to the bottom of the reception tank  17 . The air-liquid separation chamber  19  is set in an air-tight state. Connected to the top portion of the air-liquid separation chamber  19  is a suction pump  20  which sucks air out of the air-liquid separation chamber  19  to generate negative pressure. The air-discharge end of the suction pump  20  is connected via an air-discharge tube  21  to the collecting apparatus  1 . connected to the bottom of the air-liquid separation chamber  19  is a waste-ink pump  22  which sucks and discharges the waste inks retained in the air-liquid separation chamber  19 . The liquid-discharged end of the waste-ink pump  22  is connected to the collecting apparatus  1  via a liquid-discharge tube  23 . 
     In a case where the collecting apparatus  1  collects the waste inks collected in the reception tank  17 , the suction pump  20  is driven to generate negative pressure in the air-liquid separation chamber  19 . This causes the waste ink in the reception tank  17  to be sucked via the suction tube  18  into the air-liquid separation chamber  19  where the ink is separated into a gas (air) and a liquid (waste ink). At this time, the air sucked by the suction pump  20  slightly contains an ink mist. The ink-mist containing air sucked by the suction pump  20  is led to the collecting apparatus  1  via the air-discharge tube  21 . Meanwhile, the waste ink sucked into the air-liquid separation chamber  19  is led to the collecting apparatus  1  via the liquid-discharge tube  23  as the waste-ink pump  22  is driven. 
     With the above-described structure, as the ink-mist containing air discharged from the air-liquid separation chamber  19  is collected by the collecting apparatus  1 , unlike in the prior art, it is unnecessary to provide a filter for trapping an ink mist on the air-discharge side of the suction pump  20 . This invention can employ the suction pump  20  of a lower discharging performance than the conventional structure that needs such a filter, and the capacity of the suction pump  20  can be made relatively smaller, thereby contributing to making the apparatus smaller. And because the ink-mist containing air is collected by the collecting apparatus  1 , the ink mist will not be discharged in the air. 
     The details of the collecting apparatus  1  will now be described referring to FIGS. 1,  3  and  4 . FIG. 3 presents a perspective view showing the individual elements assembled together, and FIG. 4 presents a perspective view depicting the holding case  40  in which the nozzle unit  50  is installed and the collection box  30  separated from the holding case  40 . 
     As shown in FIG. 4, the collection box  30  is designed into an approximately parallelepiped shape, and is made of an inexpensive disposable material like thick paper. Formed in the upper portion of one side of the collection box  30  along the lengthwise direction is an opening  32  for receiving two nozzles  52  and  53  (to be discussed later) of the nozzle unit  50 . Retained in the collection box  30  is the absorptive member  34  which absorbs waste inks (ink mists) that are led through the nozzles  52  and  53  of the nozzle unit  50 . The absorptive member  34  is partially exposed through the opening  32  in the collection box  30 . 
     The absorptive member  34  is formed by stacking a plurality of paper sheets or accordion-folding at least a single paper sheet. This absorptive member  34  is accommodated in the collection box  30  in such a way that the paper sheets extend vertically. Although FIG. 4 shows the paper sheets extending toward the nozzle unit  50  in the lengthwise direction of the collection box  30 , the absorptive member  34  may be arranged in such a way that the paper sheets extend in the widthwise direction perpendicular to the lengthwise direction. When the absorptive member  34  is set in the collection box  30  in such a manner that the paper sheets extend vertically, the absorption of the waste inks led via the nozzle unit  50  gets better, ensuring efficient absorption of the waste inks, as compared with a case where the paper sheets are stacked vertically. This was confirmed empirically. 
     The collection box  30  is to be replaced with a new one when the absorptive member  34  absorbs a predetermined amount of waste inks. The timing for replacement of the collection box  30  will be discussed later. At the time of replacing the collection box  30  with a new one, the old collection box  30  is removed from the holding case  40  and is disposed, or only the absorptive member  34  in the collection box  30  is disposed. Anyway, since the collection box  30  and the absorptive member  34  can be made of an inexpensive material like paper in this invention, the running cost can be reduced. 
     The holding case  40  which holds the collection box  30  in a detachable manner has a bottom plate  40   a  with an approximately rectangular shape large enough to mount the collection box  30 , a front plate  40   b  standing upright almost vertically from one end of the bottom plate  40   a  and two side plates  40   c  and  40   d  which has a shape of an approximately right triangle and couples the bottom plate  40   a  to the front plate  40   b.    
     A notch  41  for receiving the two nozzles  52  and  53  of the nozzle unit  50 , which will be discussed later, is formed in the upper end of the front plate  40   b . Protrusively provided on the outer surface of the front plate  40   b  are a pair of bearing sections  42   a  and  42   b  which respectively receive rotary shafts  51   a  and  51   b  of the nozzle unit  50  to be discussed later and rotatably support the nozzle unit  50 . Formed in nearly the center of the front plate  40   b  is an opening  43  with an approximately rectangular shape which receives an arc-shaped pressure surface  55  of a rock lever  54  of the nozzle unit  50  to be discussed later. 
     Provided outside the opening  43  is a sensor  44  (see FIG. 1) which detects a flat section  56  to be detected that is provided at the lower end of the rock lever  54  retreated from the opening  43 . The sensor  44  has a light-emitting section and a light-receiving section facing each other with a slit in between, and detects the to-be-detected section  56  when this section  56  comes into the slit. Provided outside the front plate  40   b  is a pin  45  (see FIGS. 5,  6  and  7 ) on which the α spring  72  for urging the rock lever  54  is installed. One end of the α spring  72  is secured to the bottom plate  40   a , and the other end is secured to the nozzle unit  50 . The α spring  72  always urges the nozzle unit  50  in such a way that the pressure surface  55  of the rock lever  54  is intervened in the holding case  40  through the opening  43  in the front plate  40   b  as shown in FIG.  4 . The quantities of the a spring and the pin  45  can be set arbitrarily. 
     Formed in the bottom plate  40   a  is a recess  46  where the to-be-detected section  56  provided at the lower end of the rock lever  54  received through the opening  43  in the front plate  40   b  is retreated. An engage plate  47  which engages with the associated corner portion of the collection box  30  set in the holding case  40  to prevent the collection box  30  from coming off is provided integrally on the end portion of the bottom plate  40   a  which is opposite to the end where the front plate  40   b  is provided upright. 
     Rotary shafts  48   a  and  48   b  which are to be fitted in rotary holes  61   a  and  61   b  of the housing  60  to be discussed later when the holding case  40  is installed in the housing  60  protrude from the respective side plates  40   c  and  40   d . The rotary shafts  48   a  and  48   b  are provided at the portions of the respective side plates  40   c  and  40   d  which extend beyond the front plate  40   b . The holding case  40  set in the housing  60  is rotatable about the rotary shafts  48   a  and  48   b  and is urged upward by the urging force of the spring  74  intervened between the holding case  40  and the housing  60 . The spring  74  is installed between the bottom face of the bottom plate  40   a  of the holding case  40  and the top face of the bottom plate  60   a  of the housing  60  which will be described later. Pins  49   a  and  49   b  which restrict the position of the rotational top end of the holding case  40  are provided on the respective side plates  40   b  and  40   c , protruding therefrom. When the holding case  40  is urged to the top end position in the housing  60 , the pins  49   a  and  49   b  abut on engaging sections  62   a  and  62   b  of the housing  60  which will be described later, thereby restricting the upward rotation of the holding case  40 . 
     The nozzle unit  50  has the pair of rotary shafts  51   a  and  51   b  which are received in the bearing sections  42   a  and  42   b  provided on the front plate  40   b  of the holding case  40 . The nozzle unit  50  further has the waste-ink nozzle  52  and the air-discharge nozzle  53  which are to be received in the notch  41  of the front plate  40   b  and in the opening  32  in the collection box  30  set in the holding case  40 , when the nozzle unit  50  is installed in the holding case  40 . The nozzles  52  and  53  are bent each at about the center and the rotary shafts  51   a  and  51   b  are provided at positions corresponding to the bent portions. That is, when the nozzle unit  50  rotates about the rotary shafts  51   a  and  51   b , the nozzles  52  and  53  rock. 
     The liquid-discharge tube  23  connected to the air-liquid separation chamber  19  via the waste-ink pump  22  is connected to the proximal end  52   a  of the waste-ink nozzle  52 , and the air-discharge tube  21  connected to the air-liquid separation chamber  19  via the suction pump  20  is connected to the proximal end  53   a  of the air-discharge nozzle  53 . 
     The nozzle unit  50  has the rock lever  54  which extends downward and rotates the nozzle unit  50  about the rotary shafts  51   a  and  51   b  to thereby change the posture of the nozzle unit  50 . The rock lever  54  has the arc-shaped pressure surface  55  which is to be received in the opening  43  in the holding case  40 . With the nozzle unit  50  installed in the holding case  40 , this pressure surface  55  is positioned into the holding case  40  via the opening  43  in the front plate  40   b  of the holding case  40  by the urging force of the α spring  72 . The flat to-be-detected section  56 , which is detected by the sensor  44  provided in the holding case  40  with the pressure surface  55  retreated from the opening  43 , is protrusively provided on the lower end of the rock lever  54 . 
     The housing  60  has an approximately rectangular bottom plate  60   a , an approximately rectangular side plate  60   b  standing upright at about the right angle from one long side of the bottom plate  60   a , a top plate  60   c  extending like a cantilever beam from the upper end of the side plate  60   b , a front plate  60   d  extending at about the right angle from one short side of the side plate  60   b  which extends almost vertically, and a side plate piece  60   e  extending like a cantilever beam from one side of the front plate  60   d  at a position facing the side plate  60   b . Those plates  60   a ,  60   b ,  60   c  and  60   d  and the side plate piece  60   e  are provided integrally. 
     The rotary holes  61   a  and  61   b , which receive the rotary shafts  48   a  and  48   b  of the holding case  40  in a rotatable fashion, are respectively formed in the side plate  60   b  and the side plate piece  60   e . Formed on the side plate  60   b  and the side plate piece  60   e  are the engaging sections  62   a  and  62   b  which respectively engage with the two pins  49   a  and  49   b  for restricting the rotational top-end position of the holding case  40 . 
     A circular seating  63  for receiving the spring  74  is provided on the top surface of the bottom plate  60   a  which faces the holding case  40 . Providing upright on one short side of the bottom plate  60   a  is an abutting section  64  with an approximately rectangular shape which abuts on a part of the bottom plate  40   a  that becomes the rotational distal end of the holding case  40  and stops the holding case  40  at its lower end position. The holding case  40  is rotatable within a given range and is elevatable between predetermined lower and upper end positions by the interaction of the pins  49   a  and  49   b , the engaging sections  62   a  and  62   b  and the abutting section  64 . 
     In installing the holding case  40  in the housing  60 , the spring  74  is placed on the seating  63  of the housing  60  and the rotary shafts  48   a  and  48   b  of the holding case  40  are inserted in the respective rotary holes  61   a  and  61   b  of the housing  60 . Under this situation, the rotational distal end of the holding case  40  is urged upward by the urging force of the spring  74 , causing the pins  49   a  and  49   b  of the holding case  40  to be engaged with the respective engaging sections  62   a  and  62   b  of the housing  60  and setting the bottom plate  40   a  of the holding case  40  slightly apart upward from the abutting section  64  of the housing  60 . FIG. 3 shows this state in which the bottom plate  40   a  of the holding case  40  is held almost horizontally. 
     Provided near the lower end of the side plate  60   b  is a limit switch  65  which detects the bottom plate  40   a  of the holding case  40  to find out the timing for replacement of the collection box  30 . The limit switch  65  has a detection lever  65   a  which is pushed by the bottom plate  40   a . The limit switch  65  detects the bottom plate  40   a  of the holding case  40  when waste inks are collected from the state in FIG.  3  and the holding case  40  rotates downward due to its weight. 
     Attached to one end of the top plate  60   c  is a guide roller  66  which rolls in contact with the top surface of the collection box  30  to guide the attachment and detachment of the collection box  30 . 
     Referring to FIGS. 5 to  7 , a description will be given below of the operation of the collecting apparatus  1  from the point of installment of the collection box  30  in the holding case  40  to the point when the collection of waste inks is completed. FIG. 5 shows the collection box  30  to be installed in the holding case  40  set in the housing  60 , FIG. 6 shows waste inks and ink mists being collected in the collection box  30 , and FIG. 7 shows the collection box  30  full of waste ink. 
     To install the collection box  30  in the holding case  40  set in the housing  60 , as shown in FIG. 5, the bottom face  30   a  of the collection box  30  is guided by the upper end of the engaging plate  47  of the holding case  40  and the top face  30   b  of the collection box  30  is guided by the guide roller  63  of the housing  60 . Then, the pressure surface  55  of the rock lever  54  of the nozzle unit  50  is pressed by the front face  30   c  of the collection box  30 . 
     In a state before installment of the collection box  30 , the rotary shafts  48   a  and  48   b  of the holding case  40  are rotatably held in the rotary holes  61   a  and  61   b  of the housing  60 , the bottom plate  40   a  of the holding case  40  is urged upward by the urging force of the spring  74 , and the pins  49   a  and  49   b  of the holding case  40  are engaged with the respective engaging sections  62   a  and  62   b  of the housing  60 . In this state, the bottom plate  40   a  of the holding case  40  is set slightly apart upward from the abutting section  64  of the housing  60 , and the limit switch  65  is OFF. 
     In this state, the rock lever  54  of the nozzle unit  50  is urged to the position shown in FIG. 5 (standby position) by the α spring  72 . That is, the pressure surface  55  of the rock lever  54  is positioned in the holding case  40  via the opening  43  of the holding case  40 . At this time, the to-be-detected section  56  protruding from the lower end of the rock lever  54  is retreated in the recess  46  provided in the bottom plate  40   a  of the holding case  40 , and the sensor provided on the holding case  40  is OFF. 
     When the front face  30   c  of the collection box  30  pushes the pressure surface  55  of the rock lever  54 , the rock lever  54  is rocked, against the urging force of the α spring  72 , to the position (waste position) where the pressure surface  55  is retreated from the opening  43  of the holding case  40 . As a result, the collection box  30  is pushed to a predetermined position in the holding case  40 , the lower portion of the rear end of the collection box  30  is engaged with the engaging plate  47  of the holding case  40 , causing the collection box  30  to be installed at the predetermined position in the holding case  40 . This state is shown in FIG.  6 . 
     In the state is shown in FIG. 6, the waste-ink nozzle  52  and air-discharge nozzle  53  of the nozzle unit  50  are rocked in accordance with the rocking of the rock lever  54 , and the distal ends  52   b  and  53   b  of the nozzles  52  and  53  are in slight contact with the top surface of the absorptive member  34  via the opening  32  of the collection box  30 . At this time, the nozzles  52  and  53  are tilted from the horizontal state in such a way that the distal ends  52   b  and  53   b  face downward, and come to the waste position where waste inks are disposable. When the collection box  30  is properly installed in the holding case  40  as shown in FIG. 6, the sensor  44  detects the to-be-detected section  56  protruding from the rock lever  54  of the nozzle unit  50  and becomes ON. 
     Under the condition that the sensor  44  has become ON, it is determined that the collection box  30  has been installed properly and the waste-ink pump  22  and the suction pump  20  are driven to initiate a work of collecting waste inks (ink mists). In other words, the pumps  20  and  22  are interlocked to be driven based on the detection signal from the sensor  44 . 
     When collection of waste inks starts, the absorptive member  34  set in the collection box  30  absorbs waste inks. At this time, the distal ends  52   b  and  53   b  of the nozzles  52  and  53  contact the absorptive member  34 , thus preventing the waste inks from scattering and staining the interior of the printer. 
     When the absorptive member  34  in the collection box  30  absorbs waste inks and the amount of the absorbed waste inks reaches a predetermined amount, the holding case  40  is rotated downward by the weight of the waste inks, causing the bottom plate  40   a  of the holding case  40  to abut on the abutting section  64  of the housing  60 . In other words, the urging force of the spring  74  is set in such a manner that the holding case  40  is rotated to the position shown in FIG. 7 when the amount of waste inks collected in the collection box  30  reaches the absorbable amount of the absorptive member  34 . 
     When the holding case  40  is rotated to the position shown in FIG. 7, the detection lever  65   a  of the limit switch  65  is pushed by the bottom plate  40   a  of the holding case  40 , setting the limit switch  65  ON. When the limit switch  65  becomes ON, the suction pump  20  and the waste-ink pump  22  are deactivated, completing the collection of waste inks. 
     A description will now be given of a work of replacing the collection box  30  which has become full of waste inks. 
     In the state shown in FIG. 7, the collection box  30  which has become full of waste inks is manually pulled out of the holding case  40  by a worker. At this time, the top face  30   b  of the collection box  30  is guided by the guide roller  63 . As waste inks are absorbed and held by the absorptive member  34 , the waste inks will not drop even when the collection box  30  is tilted. The removed collection box  30  is to be disposed as it is. 
     When the collection box  30  is removed from the holding case  40 , the holding case  40  is hopped up by the urging force of the spring  74  and is returned to an approximately horizontal state. At this time, the rock lever  54  of the nozzle unit  50  is rocked by the urging force of the α spring  72 , causing the pressure surface  55  to be received in the holding case  40  through the opening  43 . At the same time, the waste-ink nozzle  52  and air-discharge nozzle  53  of the nozzle unit  50  are also rocked, tilting the distal ends  52   b  and  53   b  of the nozzles  52  and  53  upward and setting them to the standby position where waste inks are not disposable. Since the waste-ink nozzle  52  and air-discharge nozzle  53  of the nozzle unit  50  are tilted to the standby position shown in FIG. 5 at the time the used collection box  30  is pulled out, it is possible to prevent waste inks (or ink mists) remaining in the nozzles  52  and  53  from dropping, so that the waste inks will not stain the interior of the printer. 
     After the used collection box  30  is removed, a new collection box is installed in the holding case  40  in the above-described manner. 
     According to this embodiment, as described above, the nozzles  52  and  53  of the nozzle unit  50  are set to the waste position at the same time as the collection box  30  is installed in the holding case  40 , while the nozzles  52  and  53  of the nozzle unit  50  are set to the standby position at the same time as the collection box  30  is removed. It is therefore possible to simplify the structure for connecting the collection box  30  to the nozzles  52  and  53 . This can ensure quicker attachment and detachment of the collection box  30  and facilitate replacement of the collection box  30 . Because the distal ends of the nozzles  52  and  53  are tilted upward with the nozzles  52  and  53  are set to the standby position, waste inks will not drop at the time of replacing the collection box  30 , preventing the waste inks from staining the peripheral members. 
     This invention is not limited to the above-described embodiment, but may be modified in various other forms within the spirit or scope of the invention. Although the foregoing description of the embodiment has been given with reference to the structure that is associated with an ink of a single color, this invention is not limited to this type but may be adapted to an ink-jet printer which uses inks of four colors as shown in FIG.  8 . 
     The apparatus in FIG. 8 has four air-liquid separation chambers  71   a ,  71   b ,  71   c  and  71   d  for sucking waste inks of the individual colors that are discharged from unillustrated recording heads for the respective colors. Suction pumps  72   a ,  72   b ,  72   c  and  72   d  for generating negative pressures in the respective chambers are respectively connected to the chambers, and the air-discharge ends of the individual suction pumps are connected to the collecting apparatus  1  via respective air-discharge tubes  73   a ,  73   b ,  73   c  and  73   d . Waste-ink pumps  74   a ,  74   b ,  74   c  and  74   d  are respectively connected to the bottom plates of the chambers  71   a ,  71   b ,  71   c  and  71   d , and the liquid-discharge ends of those waste-ink pumps are connected to a single liquid-discharge tube  75  which is connected to the collecting apparatus  1 . 
     The four air-discharge tubes  73   a ,  73   b ,  73   c  and  73   d  and one liquid-discharge tube  75  are connected to the above-described nozzle unit  50 , so that waste inks and ink mists of the individual colors will be absorbed and held by the absorptive member  34  of the collection box  30  in the above-described manner. 
     The provision of the four air-discharge tubes  73   a ,  73   b ,  73   c  and  73   d  for discharging ink mists of the individual colors can prevent noise from being generated by air discharge and can reduce the height of the nozzle unit  50 . That is, since a relatively small amount of a waste ink flows in each of the waste-ink pumps  74   a ,  74   b ,  74   c  and  74   d , the single liquid-discharge tube  75  does not cause a problem of noise, while if the individual air-discharge tubes are replaced with a single tube, the air-discharging sound becomes louder. In this respect, four air-discharge tubes are provided. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.