Abstract:
An objective of the invention is to eliminate the need of a frequent dust waste by the user and to provide efficient device for wasting the dust that has been collected in the robot cleaner. The invention provides a robot cleaner capable of discharging dust out to a dust discharge station, wherein the robot cleaner is capable of moving autonomously to collect dust, the robot cleaner comprising: a dust container for storing dust; a dust inlet for collecting dust into the dust container; and an opening and closing mechanism of the dust container, provided at a bottom surface of the robot cleaner, for discharging dust collected in the dust container.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of a Provisional Application No. 61/367,723, filed on Aug. 1, 2010. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a robot vacuum cleaner capable of discarding ash easily and a dust discharge station thereof. 
     BACKGROUND ART 
     A robot cleaner cleans floors in a house autonomously and is expected to be a very useful device that may replace a substantial portion of conventional non-robot vacuum cleaners. Conventional systems are proposed which deal with wasting dust in robot cleaners. 
     U.S. Pat. No. 5,787,545 describes a system including a discharge unit for discharging dust from a robot cleaner. U.S. Pat. No. 7,053,578 describes a system that discharges dust from the bottom of the robot cleaner using a suction-extraction assembly that generates negative pressure in a charging station. U.S. Pat. Nos. 6,076,226 and 6,327,741 describe systems that collect dust from above the robot cleaner driven by a central processing unit. 
     SUMMARY OF THE INVENTION 
     The above conventional systems need relatively complex devices inside and apparently need to generate negative pressure in a part of the station to collect dust in the robot cleaner. Further, the way for the user to discard dust from the station is similar to ordinary vacuum cleaner in spite of the dust being already collected in the robot cleaner. 
     Furthermore, it is difficult to discharge dust completely in a multi-stage cyclone cleaner. 
     Compared with ordinary non-robot vacuum cleaners, there are the following problems associated with a robot cleaner. 
     (1) need of a frequent dust waste by the user due to small dust capacity 
     (2) easy to waste dust from a dust container 
     (3) low suction power 
     The above conventional systems do not solve all of the above problems well. 
     An objective of the present invention is to solve the above problems (1) to (3) well and to eliminate the need of a frequent dust waste by the user and to provide efficient device for wasting the dust that has been collected in the robot cleaner. The present invention also provides a multi-stage cyclone cleaner that can discharge dust excellently. 
     The apparatus of the present invention have elements as described in the claims. 
     According to an aspect of the invention, there is provided a robot cleaner capable of discharging dust out to a dust discharge station, wherein the robot cleaner is capable of moving autonomously to collect dust, the robot cleaner comprising: a dust container for storing dust; a dust inlet for collecting dust into the dust container; and an opening and closing mechanism of the dust container, provided at a bottom surface of the robot cleaner, for discharging dust collected in the dust container. 
     According to an aspect of the invention, there is provided a dust discharge station capable of collecting dust from a vacuum cleaner, comprising: a vacuum cleaner pedestal for providing a pedestal for the vacuum cleaner and locating the vacuum cleaner at a dust discharge position; a dust receiver provided at the vacuum cleaner pedestal and adapted to receive dust from the vacuum cleaner at the dust discharge position; and a container holder located beneath the dust receiver, for holding a station dust container; and wherein the dust discharge station receives dust collected by the vacuum cleaner from the vacuum cleaner as a result of at least a gravity force and stores into the station dust container by providing a path of dust by the dust receiver and the station dust container. 
     According to an aspect of the invention, there is provided a multi-stage cyclone cleaner comprising: a first cyclone having a floor air inlet and an outlet at center of the first cyclone, for separating dust; a plurality of second cyclones for separating relatively smaller dust than the first cyclone, wherein each of the second cyclones is smaller than the first cyclone, and air from the outlet of the first cyclone is supplied into inlets of the second cyclones; and a dust discharge enhancing mechanism for enhancing a removal of dust inside the dust container, selected from a group consisting of a blower, a shake mechanism, and an agitator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a partially cross-sectional side view of a robot cleaner system  1  according to an embodiment of the invention. 
         FIG. 2A  shows a partially cross-sectional side view of a robot cleaner system  1  according to an embodiment of the invention upon the dust discharge and a cover of the robot cleaner system. 
         FIG. 2B  shows a side view of a dust inlet valve in the robot cleaner in its closed state in detail. 
         FIG. 3A  shows a partially cross-sectional side view of a robot cleaner system  1  according to an embodiment of the invention in which a valve is placed at a side of a filter from the fan and dust adhered onto the filter from the cleaner dust container side is blown back into the cleaner dust container. 
         FIG. 3B  shows a partially cross-sectional side view of a robot cleaner system  1  according to an embodiment of the invention in which a valve is placed at a side of an exit of the air flow where a final filter is located, from the fan. 
         FIG. 4  shows a flow chart of the discharge process. 
         FIG. 5  shows a partially cross-sectional side view of a robot cleaner system according to an embodiment of the invention, wherein the dust inlet is also used as a dust outlet. 
         FIG. 6A  shows a partially cross-sectional side view of a multi-stage cyclone cleaner and a cleaner station according to an embodiment of the invention. 
         FIG. 6B  shows a partially cross-sectional side view of a multi-stage cyclone cleaner according to an embodiment of the invention wherein the fan and the motor are located upward of the first and second cyclones. 
         FIG. 6C  shows a partially cross-sectional side view of a multi-stage cyclone cleaner according to an embodiment of the invention wherein the fan is located upward of the first and second cyclones but the motor is located at the center of the first cyclone and under the second cyclones. 
         FIG. 7  shows a bottom surface of the robot cleaner  50 . 
         FIG. 8  shows a bottom view of a robot cleaner of the invention using fan-shaped cover plates. 
         FIG. 9A  shows a bottom view of a robot cleaner according to an embodiment of the invention, wherein a rectangular cover plate and two rail guides are used. 
         FIG. 9B  shows a side view of the robot cleaner in  FIG. 9A . 
         FIG. 9C  shows a side view of a robot cleaner according to another embodiment. 
         FIG. 10  shows a bottom view of a robot cleaner having a circular cross section dust container  56 - 1 . 
         FIG. 11  shows a bottom view of a robot cleaner having the dust inlet  54  also serves as a dust outlet. 
         FIG. 12A  shows a perspective view of a manual dust discharging system according to an embodiment of the invention. 
         FIG. 12B  shows a perspective view of rail guides on the manual dust discharging system in  FIG. 12A . 
         FIG. 13  shows a perspective view of a dust collecting system having a lift mechanism. 
         FIG. 14  shows a partially cross-sectional side view of a dust collecting system of the invention having a blower  19 - 1  for removing dust inside the cleaner dust container  56 . 
         FIG. 15  shows a perspective view of a dust collecting system of the invention having an agitator comprised of a flexible string for removing dust inside the cleaner dust container  56 . 
         FIG. 16  shows a perspective view of a dust collecting system of the invention having a retractable rotating blower for removing dust inside the cleaner dust container  56 . 
         FIG. 17  shows a perspective view of a dust collecting system of the invention having a retractable rotating blower for removing dust inside the cleaner dust container  56  in the multi-stage cyclone cleaner  51  in  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will be described with reference to the drawings. Identical or similar elements are numbered the same or similar numbers. 
     (1) Overall System 
       FIG. 1  shows a side view of a robot cleaner system  1  according to an embodiment of the invention. 
     The robot cleaner system  1  includes a robot cleaner station  10  and a self-propellable robot cleaner  50  for cleaning floors  5  of the user&#39;s house. 
     The robot cleaner station  10  serves as a recharging station and a dust discharging station for the robot cleaner  50 , which comes to the robot cleaner station  10  autonomously or when it is ordered so via a remote controller. 
     (2) Robot Cleaner Station  10   
     The robot cleaner station  10  includes a dust collecting system  12  and a battery charging device  30  on top of the dust collecting system  12 . The battery charging device  30  has a contact  32  for charging a rechargeable battery  52  in the robot cleaner  50 . Alternatively, the battery charging device  30  may be a non-contact charging device using a coil for inducing electro-magnetic field. 
     The dust collecting system  12  includes a casing  13 , a cover  16 , a dust wall  18 , a conduit  21 , a station dust container  20 , a dust container holder including a holder piece  26 , an upper holder piece fastener  22 , and a lower holder piece fastener  24 . In this case, the station dust container  20  is a plastic bag to be disposed each time. 
     Using a disposable plastic bag is advantageous because the user can discard the plastic bag to the garbage area without handling the dust any more. Alternatively, the station dust container  20  may be a hard plastic container where the user can set a disposable plastic bag inside. This is advantageous for the plastic bag to not explode even when the plastic bag is full. It may be also advantageous for limiting the volume of the station dust container  20  when a stream of air blow is used to create a cyclone centrifugal system in the station dust container  20  to collect the dust in the station dust container  20 . 
     When the station dust container  20  is close to full, the user disengages the station dust container holder for discarding the plastic bag to the garbage area. 
     Preferably, the level of the top surface of the dust collecting system  12  is substantially the same as the level of a floor  5  to be cleaned so that the robot cleaner  50  can easily return to the top surface of the dust collecting system  12 . To achieve this, the dust collecting system  12  has adjustable legs made of multiple poles and joints. This is advantageous in point of adjusting to floors of various users. The dust collecting system  12  may have a door (as in  FIG. 12 ) to house the station dust container. In addition, the dust collecting system  12  may have a shape to set the system in steps of stairs to downstairs. 
     (3) Robot Cleaner  50   
     The robot cleaner  50  is a self-propellable autonomous vacuum cleaner that cleans floor  5  by itself instead of an operation by a person. Examples of a similar robot cleaner include Roomba series released by iRobot Inc. The robot cleaner  50  includes a housing, three tires  62 , a dust inlet  54 , a cleaner dust container  56 , a dust container cover  66 , a dust wall receiver  64 , a dust filter  57 , a motor and fan unit  61 , and air outlet. 
     The robot cleaner  50  collects dust  60  (Herein, dust includes any substance subjected to be collected by a robot cleaner.) using a negative pressure generated by the motor and fan unit  61  via the dust inlet  54  into the cleaner dust container  56 . 
     The cleaner dust container  56  is smaller than an ordinary vacuum cleaner because the robot cleaner  50  needs to be small due to cleaning small areas and to last the battery for a long time. That is, generally, the need to discard the dust from the cleaner dust container  56  is severe in a robot cleaner than in an ordinary vacuum cleaner. 
     A motor in the motor and fan unit  61  rotates a fan to generate a negative pressure at the dust inlet and the cleaner dust container  56  and keeps dust in the cleaner dust container  56  by separating dust from air with a filter  57 . 
     Alternatively, the separation may be done using a cyclone mechanism that separates dust from air using a centrifugal force, as will be described later. 
     The motor is powered by a rechargeable battery. Therefore, the robot cleaner  50  needs the robot cleaner station  10  to recharge the battery. 
     (4) Discharge Mechanism 
       FIG. 2A  shows a side view of a robot cleaner system  1  in  FIG. 1  upon the dust discharge. 
     When the robot cleaner  50  returns to the robot cleaner station  10  autonomously or by being carried by the user, the recharging device recharges the robot cleaner  50  and discharges the dust contained in the cleaner dust container  56 . The cover  16  located at the top surface of the dust collecting system  12  is opened automatically or by the operation of the user. Then, the dust collecting system  12  raises the dust wall  18  onto a bottom surface of the robot cleaner  50  in order to avoid the dust going outside into an open air, that is, the dust wall  18  maintains seal. In this embodiment, the dust wall  18  moves into a groove (not illustrated) formed at the bottom surface of the robot cleaner  50  in order to make sure that the dust does not go outside into an open air. 
     Meanwhile, the robot cleaner  50  opens the cover  66  to discharge the dust. The dust receiver, which is the dust wall  18 , receives the dust. The dust falls downwards into the station dust container  20  via the conduit  21  of the dust collecting system  12  as a result of at least a gravity force. 
     Upon this discharging process, at a state where the dust inlet valve  58  is shut, the robot cleaner  50  may blow air with one or more blowers  74 .  FIG. 2B  shows the dust inlet valve  58  in its closed state in detail. The dust inlet valve  58  preferably has a one-way mechanism, which opens the air path one way. The one-way mechanism preferably uses one or more hinges, which opens the air path only when there is negative pressure in the cleaner dust container  56  and not when the blower  74  is blowing. In  FIG. 2B , the dust inlet valve  58  has two plates  58 B and two hinges  58 A, wherein the two plates  58 B form an overwrapped area  58 C in order to provide good seal between the plates  58 B. 
     The blow energy of the blower  74  may be supplied using a blow mechanism dedicated for the blower  74 . Preferably, air is blown in pulse of 0.1 seconds to 5 seconds in order to decrease an overall amount of air blown so as to improve the blowing force, to prevent the station dust container  20  from explosion, and to save energy. Alternatively, the blow energy of the blower  74  may be supplied using the motor and fan unit  61  in order to more completely discard the dust. This may be achieved by stopping most of the air flow from the motor to the filter  57  using a valve mechanism, opening a valve  72  for an air path from the motor into the cleaner dust container  56 , and reversely rotating the fan at the motor and fan unit  61 . Therefore, the dust adhered onto the filter  57  from the cleaner dust container  56  side can advantageously be blown back into the cleaner dust container  56  (see  FIG. 3A ). 
     In  FIG. 3A , the valve  72  is placed at a side of the filter  57  from the fan  61 A. Alternatively, the valve  72  may be placed at a side of an exit of the air flow where a final filter  57 B is located, from the fan  61 A. In this case, the robot cleaner  50  can have a mechanism to blow small dust adhered around or at the final filter  57   b  to the dust container  56  via the valve  72  and the blower  74 . 
     Further, the robot cleaner  50  may shake itself so as to support the discharging process. The shake may be done by an electrically-powered shake unit or by moving the robot cleaner  50  forward and backwards many times using the tires or by shaking the tires, or by making the robot cleaner  50  hit onto a wall in the robot cleaner station  10 . 
     The robot cleaner  50  may have an agitator comprised of a flexible string for removing dust in the cleaner dust container  56 . Preferably, the agitator is a 100 mm long bundle of (ten) plastic fibers, each fiber having a diameter of 0.3 mm. Refer to an agitator  19 - 3  in  FIG. 16 . The agitator rotates to move like a whip, to thereby remove dust that is adhered onto the walls inside the cleaner dust container. 
       FIG. 4  shows a flow chart of the discharge process. The robot cleaner station  10  waits for the robot cleaner  50  to return to the station (Step  302 ). The station, the robot cleaner, and/or the user locates the robot cleaner to the discharge position (Step  304 ). The station, the robot cleaner, and/or the user opens the cover of the station (Step  306 ). The station, the robot cleaner, and/or the user lifts the dust wall at the station (Step  308 ). The station, the robot cleaner, and/or the user opens the cover of the robot cleaner, closes the dust inlet valve, and blows air or shakes the dust container in the robot cleaner (Step  310 ). Dust is discharged (Step  312 ). Blowing/shaking is stopped and the cover is closed (Step  314 ). The dust wall is lowered, that is, stored (Step  316 ). The station cover is closed (Step  318 ). The robot cleaner cleans pedestal of the station, that is, the top surface of the station (Step  320 ). If another cleaning session is programmed or is desired by the user, the robot cleaner starts another cleaning session (Step  322 ). 
     (5) Dust Inlet as Dust Outlet 
       FIG. 5  shows a side view of a robot cleaner system according to an embodiment of the invention, wherein the dust inlet is also used as a dust outlet. 
     Instead of discharging dust from an opening of the cleaner dust container  56  provided in addition to the dust inlet  54 , the dust may be discharged from a dust inlet  54 , which serves as an opening of the cleaner dust container  56  in addition to an opening for collecting dust from the floor  5 . This approach is advantageous in that there is no need for a complex structure. Of course, the dust inlet  54  has a mechanism to prevent the collected dust from falling down onto the floor  5  from the cleaner dust container  56  when collecting dust from the floor. Upon discharging dust from the cleaner dust container  56 , the robot cleaner  50  blows air hard using the blower  74  and/or shakes the robot cleaner  50  itself. 
     (6) Cover Using Two Cover Plates 
       FIG. 7  shows a bottom surface of the robot cleaner  50 . 
     At the bottom surface of the robot cleaner  50 , there are three tires, a cover including a first plate and a second plate, and a first assist bar and a second assist bar. The first plate and the second plate are overlapped at its center where there is a seal member (not illustrated) also. A (right) side of the first plate and a (left) side of the second plate are fastened to the robot cleaner  50  using hinges. Other side may be locked but can be separated from the robot cleaner  50  when opening the cover from the center. 
     When the cover plates are opened using opener bars (not illustrated) to unlock mechanisms, they open at directions substantially 90 degrees from the closed position so as the dust not to stick onto the cover. Upon closing the cover plates when the dust discharge is finished, closing bars may be used to close the cover plates and to lock the cover plates onto their locked positions. 
     (7) Cover Using Fan-shaped Cover Plates 
       FIG. 8  shows a robot cleaner of the invention using fan-shaped cover plates. 
     This approach uses three fan-shaped cover plates with three closer bars. This cover is especially advantageous in a cyclone vacuum cleaner for which the cleaner dust container  56  has a circular shape cross section (that is, a cylinder shape) and circular cover is desirable in order to efficiently discharge dust. The fans open as in a lens cover, which is automatically opened and closed, for digital cameras, such as LC-1 for Ricoh GX 200 released by Ricoh Co. Ltd. Instead of three fans, two, four, five, six, fans may be used. Among those, two fans or three fans are preferable. Alternatively, only one circular cover that has a hinge structure at one side may be used. 
     (8) Cover Using Two Rails 
       FIG. 9A  shows a robot cleaner according to an embodiment of the invention, wherein a rectangular cover plate and two rail guides are used.  FIG. 9B  shows a side view of the robot cleaner in  FIG. 9A .  FIG. 9C  shows a side view of a robot cleaner according to another embodiment. 
     This approach uses a substantially rectangular cover plate  66 - 2 , which is engaged into two rail guides  82 . The cover plate  66 - 2  has a pull/push member  76 - 4 . The cover plate  66 - 2  contacts to the robot cleaner  50  via a rectangular-shaped seal element (not illustrated). The seal element may be a hollow rubber, such as a weather-strip used to seal between a glass panel and a main frame in aftermarket sunroofs for automobiles, such as Event 450 series released by Signature Automotive Products (Wixom, Mich., USA). The hollow rubber can be pressed down while maintaining the seal, and is durable for horizontal movement of the cover plate. 
     The arrangement of the two rail guides  82  may be as the same as an arrangement of rail guides  33  in  FIG. 12B . 
     When opening the cover plate  66 - 2 , the cover plate  66 - 2  is guided by the two rail guides  82  to an open position at the right. This approach is advantageous for a secure closure. The pull/push member  76 - 4  may be pulled and pushed manually by the user from above the robot cleaner  50 . Alternatively, the pull/push member  76 - 4  may be pulled and pushed automatically using a gear mechanism  67  (see  FIG. 9B ) that engages with teeth created on the pull/push member  76 - 4 . 
     The pull/push member  76 - 4 C in  FIG. 9C  is guided inside the robot cleaner into a route directing upwards as compared to that of  FIG. 9B . The route reaches to the top surface of the robot cleaner, enabling the pull/push member  76 - 4 C to project outside. The gear  67 - 1  drives the pull/push member  76 - 4 C. This embodiment is advantageous in that the guide of the pull/push member  76 - 4 C is hidden from outside. All of these mechanisms for opening and closing the cover at the robot cleaner  50  may be used for opening and closing the cover at the robot cleaner station  10 . Details are not shown for simplicity. 
       FIG. 10  shows a bottom view of a robot cleaner having a circular cross section dust container  56 - 1 . In  FIG. 10 , the robot cleaner has three tires  62 , an inlet  54 , a rectangular shaped cover  66 - 1 , a dust container  56 - 1 , which has a circular cross section, two rail guides  82 , pull/push member  76 - 4 . A circular cross section dust container is advantageous in that the dust falls easily due to a uniform round shape of the wall of the dust container. 
       FIG. 11  shows a bottom view of a robot cleaner having the dust inlet  54  also serves as a dust outlet. In  FIG. 11 , dust is collected via the dust inlet  54  when cleaning the floor, and dust is discharged via the dust inlet  54 , which also serves as a dust outlet. In order to achieve this feature, the robot cleaner needs the dust discharge enhancing mechanism because the dust should not fall down easily when the robot cleaner is cleaning the floor. This approach is advantageous in that the structure is simple. 
     (9) Dust Discharge in Multi-Stage Cyclone Cleaner 
       FIG. 6A  shows a multi-stage cyclone cleaner  51  according to an embodiment of the invention when discharging dust. The multi-stage cyclone cleaner  51  is a robot cleaner which cleans floor autonomously. 
     The multi-stage cyclone cleaner  51  separates dust using cyclones where dust keeps away from the center of the cyclone due to centrifugal force generated by rotation of air flow. An example of a multi-stage cyclone cleaner is DC26 released by Dyson Technology Ltd. 
     The multi-stage cyclone cleaner  51  has a first cyclone  71 , which is for generating a first cyclone air flow around the first cyclone  71 , and a plurality of second cyclones  72  (six in this embodiment), each of which generates a second cyclone air flow and is smaller than the first cyclone  71 . The first cyclone air flow is generated because negative pressure is generated at a side of the second cyclones  72  and incoming air is supplied from a first cyclone inlet  71 - 1 . Floor air including dust enters into the cleaner  51  via an inlet  54 , and then enters into the first cyclone inlet  71 - 1 , and into the first cyclone  71 , where it separates relatively large dust from air. Relatively clean air goes out of the first cyclone  71  from its center  71 - 2  to enter into inlets  72 - 1  of the multiple second cyclones  72 . 
     The second cyclones  72  separate relatively smaller dust, such as particles having diameter of 1 to 100 μm. A part of the separated small dust falls down but some stick onto the walls of the second cyclone  72 . Relatively clean air goes out of the second cyclone  72  from its center  72 - 2  to enter into a conduit  75 , a filter  57 , and then, into a motor and fan unit  61 . There may be provided with additional cyclone in the center  71 - 2  of the first cyclone  71  to improve the dust separation property. In this case, this additional cyclone is a second cyclone and the plurality of cyclones  72  are respectively a third cyclone. The wall structure in the cleaner dust container  56  in the multi-stage cyclone cleaner  51  is relatively complex than a non-cyclone cleaner, and therefore, it is difficult to remove dust in the dust container  56 . The first and second cyclones  71 ,  72  have axes in the vertical direction, and therefore, the cyclone air flows at the first and second cyclones  71 ,  72  are generated to have vertical axis. This is advantageous because dust adhered onto the walls in the dust container  56  easily falls down at the time when the motor is not running compared with the case where the first cyclone or the second cyclones have axes not in the vertical direction. In this cleaner, there is no need for a filter in front of the fan in the air flow because the dust can be separated well using the first and second cyclones  71 ,  72 . Instead there may be a final filter  57 B behind the fan  61 A. 
     When discharging dust in a conventional multi-stage cyclone cleaner, the user opens the cover (corresponding to the cover  66 ) and uses a gravity force and may shake by oneself to discharge dust into a collector bag. However, since the wall structure in the cleaner dust container  56  in the multi-stage cyclone cleaner  51  is relatively complex than a non-cyclone cleaner, it is difficult to remove dust well. 
     Therefore, the invention utilizes a dust discharge enhancing mechanism, such as a blower  74 , described above, to remove dust at the second cyclone  72 . In addition, the invention utilizes a shake mechanism, described above, to remove dust at the second cyclone  72 . Furthermore, the invention utilizes an agitator, described above, to remove dust at the second cyclone  72 . 
       FIG. 6A  also shows a dust discharge scheme of such a cleaner. Details are not shown for simplicity. Of course, descriptions described for other embodiments can be applied to the multi-stage cyclone cleaner  51  in  FIG. 6A . For example, it may be an autonomous robot cleaner, it may have an automatic opening and closing mechanism, and it may have valves described in the above. 
     (10) Second Embodiment of Multi-Stage Cyclone Cleaner 
       FIG. 6B  shows a multi-stage cyclone cleaner according to another embodiment, wherein the fan  61 A and the motor  61 B are located upward of the first and second cyclones  71 ,  72 . Accordingly, the filter  58  is located between the second cyclones  72  and the fan  61 A. Axes of the first cyclone  71 , the fan  61 A, and the motor  61 B are substantially identical. This cleaner is advantageous because resistance of air flow at the conduit  75  in  FIG. 6A , which is relatively very long and thin, can be decreased, the size of the fan  61 A can be increased, and the exhaust air can be directed upwards from a relatively large area. 
     (11) Third Embodiment of Multi-Stage Cyclone Cleaner 
       FIG. 6C  shows a multi-stage cyclone cleaner according to another embodiment, wherein the fan  61 A is located upward of the first and second cyclones  71 ,  72  but the motor  61 B is located at the center of the first cyclone  71  and under the second cyclones  72 . Since there is no need for the space for the motor  61 B above the fan  61 A, this approach is advantageous in that the overall height can be lowered as compared with the cleaner in  FIG. 6B , enabling the cleaner to go into places of low height. However, there is a need for a longer shaft between the motor  61 B and the fan  61 A, to fix the motor  61 B to the cleaner body, to hold the shaft of the motor  61 B with respect to the cleaner body, and to protect the shaft, which may be greased, from dust. 
     In order to solve the above problems, the cleaner has a motor shaft holder  78 A and a motor holder  78 B. The motor shaft holder  78 A surrounds the motor shaft, which connects the motor  61 B and the fan  61 A, and is fixed to the surface  72 S of the second cyclones  72  and to the motor  61 B. Therefore, the motor shaft is substantially not exposed to dust, that is, the motor shaft is exposed to dust at only at a region close to the fan  61 A. Preferably, there is a mechanism to reduce the friction between the motor shaft and the motor shaft holder  78 A. For example, this mechanism uses a bearing, or low friction plastics. In addition, the motor  61 B is supported by a motor holder  78 B to the bottom part of the cleaner. Preferably, the motor holder  78  is a plurality of elongate members extending radially from the motor  61 B and are fixed to the wall of the dust container  58  and the supporting member of the wall. Even when the motor  61 B and the motor holder  78 B are located in the dust container close to the cover  66 , the cleaner can open the cover  66  and to waste dust because there is a dust discharge enhancing mechanism to drop the dust. It should be noted that the multi-stage cyclone cleaners  51  in  FIGS. 6A ,  6 B and  6 C do not need to be used with a dust discharge station such that the user may discharge dust to a garbage can or a plastic bag, preferably with the dust discharge enhancing mechanism being activated to easily discharge dust out of the cleaner. 
     (12) Manual Dust Discharging System 
       FIG. 12A  shows a manual dust discharging system according to an embodiment of the invention. 
     Although an automatic robot cleaner system is advantageous to reduce human labor, a manual robot cleaner system is advantageous to provide a simple and robust solution. 
     The dust collecting system  12  is set on the floor  5  and the top surface of the dust collecting system  12  is higher than the floor  5 . With this way, the user does not need to create or find a concave area at the floor  5 . When a cleaning session is finished, the robot cleaner  50  is lifted by the user and set to the recharging and discharging position. Fence  42  provided on three edges of the top surface of the dust collecting system  12  helps to locate the robot cleaner  50  to the recharging and discharging position and to prevent the robot cleaner  50  from falling down even if the robot cleaner  50  started to move, and to prevent the dust falling down from the top surface. 
     The dust collecting system  12  has a pull lid  37  in order to hide the dust collector  20 . The pull lid  37  has a hinge mechanism at the bottom side thereof and a pull knob  37 - 1  at its upper part. 
     The cover plate  16  and its sealing mechanism are similar to that of the cover  76 - 3  shown in  FIG. 8 . There is a sealing element around the retracted dust wall  18  on the top surface of the dust collecting system  12 . The sealing element may be a hollow rubber, such as a weather-strip used to seal between a glass panel and a main frame in aftermarket sunroofs for automobiles, such as Event 450 series released by Signature Automotive Products (Wixom, Mich., USA). The hollow rubber can be pressed down while maintaining the seal, and is durable for horizontal movement of the cover plate  16 . 
     The user pulls the pull/push tab  18 - 5  of the cover plate  16  of the dust collecting system  12  to open the cover of the dust collecting system  12 . Then, the user pulls a lever  40  to lift the dust wall  18  to an intermediate position, where the lever  40  is locked temporarily. The lever  40  and the dust wall  18  are mechanically associated with each other by a gear mechanism. Alternatively, the dust wall  18  may be lifted electrically using a motor. Next, while the lever  40  is still at its intermediate position, the user touches a button on the robot cleaner  50  to open the cover of the robot cleaner  50  electrically and to expose a dust wall receiving element  64  of the robot cleaner  50 . While the user holding the robot cleaner  50 , the user pulls the lever  40  to a discharge position so as to lift the dust wall  18  further and therefore to engage the dust wall  18  to the dust wall receiving element  64 . 
     Then, the robot cleaner  50  blows dust with its blower  74  and/or shakes to discharge dust from the cleaner dust container  56 . Upon finishing the dust discharge, the user pushes the lever  40  back and pushes a button on the robot cleaner  50  to cover the cleaner dust container  56 . Then, after having the robot cleaner  50  clean the top surface of the dust collecting system  12 , the user may finish the robot cleaning, or may lift the robot cleaner  50  and puts it to the floor  5  again for further cleaning. 
     Although the dust collecting system  12  may operate non-electrically, a part of the functions may operate electrically. 
     (13) Robot Cleaner-Lifting Dust Collecting System  12   
     When the top surface of the dust collecting system  12  is at a higher level than the floor  5 , the robot cleaner  50  needs to be automatically lifted to achieve an automatic discharge system.  FIG. 13  shows a dust collecting system having a lift mechanism. 
     The dust collecting system  12  uses a lift mechanism  48  to hook the robot cleaner  50  and to lift the robot cleaner  50  to the surface of the dust collecting system  12 . The hook does not work for an object other than the robot cleaner  50  by a checking mechanism using an authentication technique. 
     First, the robot cleaner  50  approaches to the lift mechanism  48  by self-propelling on the floor  5 . Then, a hook projects at a location  48 - 1  to hook the robot cleaner  50 . Next, the hook moves upwards to a location  48 - 2 . Then, the hook projects from the top surface of the dust collecting system  12  for about a half size of the robot cleaner  50 . Then, the hook descends onto the top surface. 
     (14) Dust Collecting System  12  Having Dust Blower/Agitator/Shake Mechanism 
       FIG. 14  shows a dust collecting system of the invention having a blower  19 - 1  for removing dust inside the cleaner dust container  56 . This approach is a combination of the dust collecting system  12  and the dust blower  74  of the robot cleaner  50 . This approach is advantageous in that complex mechanisms in the robot cleaner  50  are avoided. In addition, this approach is advantageous in that the blowing direction can be from downward of the dust container  56  in the robot cleaner  50  because the dust can be blown better from downward due to the shape of the dust container  56 , especially when the robot cleaner  50  is the multi-stage cyclone cleaner  51  shown in  FIG. 6A . 
       FIG. 15  shows a dust collecting system of the invention having an agitator comprised of a flexible string for removing dust inside the cleaner dust container  56 . Preferably, the agitator is a 100 mm long bundle of (ten) plastic fibers, each fiber having a diameter of 0.3 mm. The agitator rotates to move like a whip, to thereby remove dust that is adhered onto the walls inside the cleaner dust container  56 . 
       FIG. 16  shows a dust collecting system of the invention having a retractable rotating blower for removing dust inside the cleaner dust container  56 . The retractable rotating blower  19 - 2  is provided in the dust collecting system  12 . The retractable rotating blower  19 - 2  is usually at its retracted state (not illustrated). Upon blowing air from one or more holes on a blowing rotator  19 - 2   a , the retractable rotating blower  19 - 2  is extended to have a longer length. Blowing air pressure may be used for extending the blower. The blowing rotator  19 - 2   a  can be rotated around an axis of the blower. When air is blown from the blowing rotator  19 - 2   a , the blowing rotator  19 - 2   a  rotates because of the force generated by the blowing air. A rotating blower is preferable because it is possible to blow a larger area of the walls in the dust container  56 . 
     Each of the blower, the agitator, and the shake mechanism, and the like, in the dust collecting system  12  and in the robot cleaner  20  constitutes a dust discharge enhancing mechanism. 
       FIG. 17  shows a dust collecting system of the invention having a retractable rotating blower for removing dust inside the cleaner dust container  56  in the multi-stage cyclone cleaner  51  in  FIG. 6A . Since it is difficult to discharge dust completely in a multi-stage cyclone cleaner  51  due to complex walls in the dust container  56 , a retractable rotating blower  19 - 2   b  or other dust discharge enhancing mechanism is especially preferable in a multi-stage cyclone cleaner. 
     (15) Notes 
     In the above embodiments of the invention, several embodiments of the dust collecting system  12 , the robot cleaner  50 , and their components are shown. Although not all of the combinations are described herein, all the combinations of the elements construct embodiments of the invention and are incorporated herein.