Patent Publication Number: US-7587152-B2

Title: Powder transport device and image forming system

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a powder transport device for use in an image forming devices, such as a copier, a facsimile or a printer. More specifically, this invention relates to a powder transport device including a mass powder storing part, and to an image forming system including the powder transport device. 
   2. Description of the Related Art 
   Conventionally, supply of toner to an image forming device is performed using a toner container which has a 0.5-2 liter capacity. This is because exchange of toner container is performed by the user and the use of the toner container having such capacity is considered suitable in the light of operability of the user. 
   However, if the toner container having such capacity is used, there is a problem that exchange of toner container must be performed frequently by a certain user, such as a print service company, who consumes a lot of toner. 
   Therefore, it is desired to reduce the frequency of exchange of toner container. To obviate the problem, Japanese Patent No. 3534159 discloses a toner device which is adapted for accommodating two or more toner containers. With this toner device, the period of consumption of all the toner containers can be prolonged. The empty-state toner containers can be exchanged even during image formation of the image forming device, and it is possible prevent operation of the image forming device from being stopped unnecessarily. However, if the capacity of each toner container in this toner device is the same, the frequency of exchange remains unchanged. Reducing the frequency of exchange of the toner containers is difficult for this toner device. 
   Moreover, the toner container disclosed in Japanese Laid-Open Patent Application No. 2005-024622 has a large capacity, and it is possible to reduce the exchange frequency of the toner container because of the large-capacity container. However, since toner is discharged from the lower part of this toner container and supplied to a toner receiving device, if separation or breakage of the toner piping occurs, much of the stored toner may be scattered. 
   Moreover, it is desired to increase the amount of storage of a mass toner storing container for heavy-consumption users to an amount larger than that of a conventional toner storing container. The increased amount of the storage mass toner storing container is, for example, in a range of 5-100 liters in capacity. However, toppling of the mass toner storing container may take place during conveyance or storage, earthquake, etc. 
   Furthermore, if an inexperienced worker mistakes connecting operation of the mass toner storing container at the time of exchange work, it is likely that the amount of scattering of the stored toner increases, the joint portion of the container is damaged. 
   SUMMARY OF THE INVENTION 
   According to one aspect of the invention, there is provided an improved powder transport device and image forming system in which the above-described problems are eliminated. 
   According to one aspect of the invention there is provided a powder transport device which is adapted to prevent the powder scattering and the toppling of the powder storing container and ensure easy exchange work. 
   In an embodiment of the invention which solves or reduces one or more of the above-mentioned problems, there is provided a powder transport device which transports powder to a powder receiving device by mixing the powder to an air flow, the powder transport device including a powder storing unit having a powder storing part which stores powder, and a container unit having a container part in which the powder storing unit is accommodated, the powder storing unit comprising: a motor part for operating the powder storing unit; an electrical wiring for transmitting an electric signal sent from the motor part or a driving current sent to the motor part in order to drive the motor part; and a first connector for providing electrical conduction between the electrical wiring and an external wiring, the container unit comprising a second connector electrically connected to the external wiring, the second connector being engaged with the first connector so that the first connector provides electrical conduction between the electrical wiring and the external wiring. 
   In an embodiment of the invention which solves or reduces one or more of the above-mentioned problems, there is provided a powder transport device which transports powder to a powder receiving device by mixing the powder to an air flow, the powder transport device comprising: a powder storing unit having a powder storing part which stores powder and having a first connector provided therein; and a container unit having a container part in which the powder storing unit is accommodated and having a second connector provided therein, wherein the powder transport device is constituted so that, when accommodation of the powder storing unit in the container part is completed, the first connector and the second connector are electrically connected together and transmission of an electric signal and/or a driving current between the powder storing unit and the container unit is allowed. 
   In an embodiment of the invention which solves or reduces one or more of the above-mentioned problems, there is provided an image forming system in which an image forming device and a powder transport device are provided, the powder transport device including a powder storing unit having a powder storing part which stores powder, and a container unit having a container part in which the powder storing unit is accommodated, the powder storing unit comprising: a motor part for operating the powder storing unit; an electrical wiring for transmitting an electric signal sent from the motor part or a driving current sent to the motor part in order to drive the motor part; and a first connector for providing electrical conduction between the electrical wiring and an external wiring, the container unit comprising a second connector electrically connected to the external wiring, the second connector being engaged with the first connector so that the first connector provides electrical conduction between the electrical wiring and the external wiring, wherein the image forming device performs image formation using the powder transported by the powder transport device. 
   According to embodiments of the powder transport device and the image forming system of the invention, it is possible to prevent the powder scattering and the toppling of the powder storing container and ensure easy exchange work. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects, features and advantages of the present invention will be apparent from the following detailed description when reading in conjunction with the accompanying drawings. 
       FIG. 1  is a diagram showing the composition of an image forming system in an embodiment of the invention. 
       FIG. 2  is a diagram showing the connected state of a powder transport device and an image forming unit in this embodiment. 
       FIG. 3  is a perspective view of the powder transport device of this embodiment. 
       FIG. 4A ,  FIG. 4B ,  FIG. 4C  and  FIG. 4D  are diagrams showing the installed state of a powder storing unit. 
       FIG. 5  is a diagram showing the arrangement of electrical wiring connectors in the powder transport device of this embodiment. 
       FIG. 6  is an enlarged view of the electrical wiring connectors in the powder transport device of this embodiment. 
       FIG. 7A  and  FIG. 7B  are diagrams showing the composition of the electrical wiring connector. 
       FIG. 8  is a diagram showing the electrical wiring connectors in which the arrangement of pins is changed to set the connectors in a non-compatible state. 
       FIG. 9  is a diagram showing the electrical wiring connectors in which the shape is changed to set the connectors in a non-compatible state. 
       FIG. 10  is a diagram showing the electrical circuit of an electronic lock when the powder transport device is provided with the electrical wiring connectors. 
       FIG. 11  is a diagram showing a container unit which has a regulation member which regulates the direction of movement of the casters. 
       FIG. 12  is a diagram for explaining the regulation of horizontal rotation of the caster wheels by the regulation member. 
       FIG. 13  is a diagram showing the internal composition of the powder transport device of this embodiment. 
       FIG. 14  is a diagram showing the composition of the powder storing unit. 
       FIG. 15  is a timing chart for explaining the control process performed by the powder transport device in an embodiment of the invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   A description will be given of embodiments of the invention with reference to the accompanying drawings. 
     FIG. 1  shows the composition of an image forming system in an embodiment of the invention. 
   In  FIG. 1 , reference numeral  1  denotes an image forming unit, reference numeral  2  denotes a sheet feeding unit, and reference numeral  3  denotes a post-processing unit which performs sorting, stapler fixing, etc. 
   The image forming unit  1  is an electrophotographic image forming device (copier) which uses powder toner for image formation. The sheet feeding unit  2  includes a wing  2   a  of the sheet feeding tray projecting on the right-hand side of the sheet feeding unit  2 , and a powder transport device  20  which constitutes a toner supplying device and is provided beneath the wing  2   a  of the sheet feeding unit  2 . 
   In addition, the installation position of the powder transport device  20  can be set up arbitrarily. However, in this embodiment, the dead space of sheet feeding unit  2  beneath the projecting wing  2   a  of the sheet feeding unit  2  is used as the installation position of the powder transport device  20 . 
   The powder transport device  20  may be united with the image forming device. Alternatively, the powder transport device  20  may be detachably provided outside the image forming device. When the powder transport device  20  is provided inside the image forming device, the control of the powder transport device  20  by the image forming device can be performed easily. When the powder transport device  20  is provided outside the image forming device, the exchange of the powder transport device  20  can be performed easily at the time of failure of the powder transport device. 
     FIG. 2  shows the connected state of the powder transport device  20  and the image forming unit  1 .  FIG. 3  is a perspective view of the powder transport device  20 . 
   In the image forming unit  1  of  FIG. 2 , a photoconductor drum  4  which is an image support object is provided. When the photoconductor drum  4  is rotated clockwise by the motor (which is not shown), the surface of the photoconductor drum  4  is uniformly charged by the charging device (which is not shown). The charged surface of the photoconductor drum  4  is exposed to scanning of a light beam (for example, a laser beam) applied thereto by the optical writing unit (not shown), so that an electrostatic latent image is formed on the surface of the photoconductor drum  4 . This electrostatic latent image is turned into a visible image with toner by the developing device  5 . The visible toner image is transferred to a recording medium (copy sheet), which is fed from and transported at predetermined timing by the sheet feeding part or the sheet feeding unit  2  (which is arranged at the lower part of the image forming device) by the transfer belt  6  which is a transfer device. 
   The recording medium to which the toner image is transferred is transported to the fixing device  7 , so that the toner image is fixed to the recording medium permanently. 
   On the other hand, the remaining toner which remains on the surface of the photoconductor drum  4  is removed from the surface of the photoconductor drum  4  by the cleaning device  8 . By repeating the above operations, image formation can be performed sequentially on a number of recording mediums. Moreover, the remaining toner of the transfer belt  6  is cleaned by the belt cleaning  10 . 
   As shown in  FIG. 2  and  FIG. 3 , the powder transport device  20  in this embodiment includes a container unit  21  which is fixed to the powder transport device  20 , and a powder storing unit  31  which is detachably mounted to the container unit  21 . 
   And the casters  31   a  are provided on the bottom of the powder storing unit  31  so that movement of the powder storing unit  31  can be done easily when it is detached from the container unit  21 . In this powder storing unit  31 , a powder storing part  32  in which the toner supplied to the image forming unit  1  is stored, and a waste toner recovery container  40  which is provided above the tank of the powder storing part  32 . Moreover, the pumps  22  and  23  which transport toner and the air pumps  24  and  25  which supply air are provided in the container unit  21 . 
   The toner supplied from the powder transport device  20  to the image forming unit  1  may be also transported to the development hopper (not shown) of the direct developer  4 . However, in this embodiment, the toner is supplied to the toner hopper  9  which is provided in the image forming unit  1 . 
   And the toner sent to the toner hopper  9  is transported to the development hopper of the developing device  5  through the transport passage  11  by the toner transport unit, such as a toner transport coil or a powder pump. 
   The connection between the powder transport device  20  and the powder storing unit  31  is performed through the powder storing unit connection part  31   b  and the container unit connection part  21   d  shown in  FIG. 3 . 
   The powder storing unit connection part  31   b  includes the suction nozzle and the air supply nozzle. In this embodiment, the powder storing unit connection part  31   b  is connected to the container unit connection part  21   d.    
   Thereby, while the toner of the powder storing part  32  is not scattered, it can be supplied through the powder storing unit  31  and the powder transport device  20  to the developing device  5  of the image forming device. Moreover, air can be supplied from the air pumps  24  and  25  to the powder storing part  32 . 
     FIG. 4A ,  FIG. 4B ,  FIG. 4C  and  FIG. 4D  show the installed state of the powder storing unit  31 . As shown, the powder storing unit connection part  31   b  is fixed with the connecting member in which the suction nozzle and the air supply nozzle are united, and the connecting member of the powder storing unit connection part  31   b  is connected to the container unit connection part  21   d . Accordingly, the effect to prevent an inexperienced worker from mistaking the connecting operation can be increased, and the scattering of the stored toner can be prevented more efficiently. Furthermore, because of the use of the connecting member which is connected to the container unit connection part  21   d , the working efficiency of the connecting operation can be increased. 
     FIG. 5  shows the arrangement of the electrical wiring connectors in the powder transport device of this embodiment. 
   As shown in  FIG. 5 , the drawer connector  79   a  is provided on the powder storing unit  31  as a first connector, and the drawer connector  79   b  is provided on the container unit  21  as a second connector. 
   The electric supply path is formed by using the drawer connectors  79   a  and  79   b . The electrical wiring and connectors for driving the electrical parts including the air pump which supplies air through the porous member and the detection sensor are provided in the container unit. The driving current from the power supply outside the powder storing unit  31  can be supplied to the air pump, and the detection result from the detection sensor can be transmitted to the container unit  21  or the CPU provided in the image forming device. 
   The positions where the electrical wiring connectors  79   a  and  79   b  are arranged are determined arbitrarily. However, it is preferred that, as shown in  FIG. 5 , the first connector  79   a  is provided on the side surface of the powder storing unit  31 , and the second connector  79   b  is provided on the back surface of the door of the container unit  21 . 
   In a case in which the connector connects the large-sized powder storing unit  31  is contained in the container part, if the composition in which the connector at the insertion place is connected is adopted, the insertion place cannot be seen from the user. The connecting operation may be mistaken by the user, and the load exceeding the withstand load of the connector may be exerted around the connector by the force of inertia by the weight of the container unit. There is a problem that the connector and the surrounding mechanism may be damaged by the unsuitable connecting operation of the user. 
   However, with the use of the composition of  FIG. 5 , electric connection can be recovered in accordance with the door closing operation, and the connector is pressed by the member with a comparatively light weight which is provided on the back surface of the door of the container unit  21  and can be easily recognized by the user. Therefore, it is possible to prevent the damaging of the connector by the unsuitable connecting operation of the user. 
   Moreover, the presence of the powder storing unit  31  can be easily checked by the user, and the malfunction of the powder transport device in the state where the powder storing unit  31  is vacant can be prevented, and the toppling of the container unit during storage, earthquake, etc. can be prevented. 
   Next, the electrical wiring connectors  79   a  and  79   b  in this embodiment will be explained.  FIG. 6  is an enlarged view of the electrical wiring connectors  79   a  and  79   b .  FIG. 7A  and  FIG. 7B  show the composition of the electrical wiring connector  79   a.    
   As shown in  FIG. 6 , the electrical wiring connector  79   a  is movable vertically and horizontally. Specifically, a clearance between the shaft diameter of the screw  79   a   1  and the hole diameter of the drawer connector  79   a  is provided as shown in  FIG. 7B , and the electrical wiring connector  79   a  can be moved vertically and horizontally. Therefore, the fine gap between the positions of the connectors  79   a  and  79   b  can be adjusted. The connecting operation of the connectors  79   a  and  79   b  can be performed smoothly and easily. Moreover, it is possible to prevent the damaging of the connectors  79   a  and  79   b  by unsuitable connection of the connectors  79   a  and  79   b  by the user. 
     FIG. 8  shows the electrical wiring connectors in which the arrangement of pins is changed to set the connectors in a non-compatible state.  FIG. 9  shows the electrical wiring connectors in which the shape is changed to set the connectors in a non-compatible state. 
   The door  21   c  of the container unit  21  is not fitted to the powder storing unit  31  by changing the pin arrangement or the connector shape. It is ensured that only the powder storing unit  31  which is tuned up to the container units  21  is selected by the user who performs the connecting operation of the connectors. 
   For example, suppose that the problem of an image with excessive background stain arises by the performance of a specific image forming device, and it is necessary to change the charging characteristics of the toner which is filled up in the corresponding powder storing unit  31  to a level higher than the normal level at the time of shipment. In such a case, if the shape of the connectors  79   a  and  79   b  is changed and such connectors are attached to the powder storing unit  31  and the container unit  21 , then it is possible to prevent the incorrect toner storing by confusion of the improved powder storing unit and the normal powder storing unit. 
     FIG. 10  shows the electrical circuit of an electronic lock when the powder transport device is provided with the electrical wiring connectors. 
   In  FIG. 10 , reference numeral  80  denotes a MPU (microprocessor unit), and reference numerals  81  and  82  denote motor drive circuits for rotating the stepping motor  83 . The rotation of the stepping motor  83  in the forward or reverse rotation direction can be controlled freely by changing the phases ψ 1  and ψ 2  of the driving pulses outputted from the motor drive circuits  81  and  82 . 
   Moreover, in  FIG. 10 , reference numeral  84  denotes an EEPROM (memory) which stores the control program and the password, reference numeral  85  denotes a power-on-reset circuit which resets the electrical circuit of the electronic lock to its initial state automatically at the time of power up, reference numeral  86  denotes a time constant circuit for a clock oscillation, reference numeral  87  denotes an electronic buzzer, and reference numeral  89  denotes a detection circuit which detects connection of the electrical wiring connectors. 
   When the powder storing unit  31  is contained in the container unit  21  and the door  21   c  of the container unit  21  is shut, the door  21   c  of the container unit  21  and the powder storing unit  31  are connected together by the electrical wiring connectors  79   a  and  79   b . When the connection of the electrical wiring connectors  79   a  and  79   b  is detected by the detection circuit  89 , the detection information is transmitted from the circuit  89  to the MPU  80  so that the locking of the door  21   c  is performed. 
   Since the powder storing unit  31  in this embodiment is a large-sized powder storing unit  31 , it is expected that various operations, such as clearing up of the surrounding units, are performed at the time of setting of the powder storing unit  31 . If an operation start switch is provided at a different position, it is likely that the locking of the door  21   c  may be forgotten because the operation of turning on and off the switch must be performed. 
   However, with the use of the above-mentioned electronic lock of  FIG. 10 , it is possible to preventing failure of the locking operation of the door  21   c . And it is possible to prevent the mistaking of the connecting operation by an unfamiliar user and the theft of the powder storing unit  31  during automatic operation. 
     FIG. 11  shows the container unit  21  which has a regulation member which regulates the direction of movement of the casters. As shown, the regulation members  101  which regulate the direction of movement of the casters  31   a  are provided at both the side ends of the bottom of the container unit  21 . 
     FIG. 12  is a diagram for explaining the regulation of the horizontal rotation of the caster wheels. 
   When the casters  31   a  are rotated in the horizontal direction even if the side of the powder storing unit  31  is regulated, it is difficult to smoothly move the powder storing unit  31  into the container unit  21 . 
   In the powder storing unit  31  of this embodiment, the rotation of the casters  31   a  in the horizontal direction is regulated, and it is possible to move the powder storing unit  31  into the container unit  21  along the regulation members  101  or carry the powder storing unit  31  on the regulation members  101 . 
   When the powder storing unit  31  is carried on the regulation members  101 , the distance between the regulation members  101  can be set up to be equal to or slightly greater than the distance between the casters of the powder storing unit  31 . For this reason, accommodation of the powder storing unit  31  in the container unit  21  may be carried out by locking the movement of the casters  31   a  and moving the regulation members  101  or by moving the regulation members  101  using the casters  31   a.    
   Thereby, it is possible to easily carry out setting of the powder storing unit  31  in the predetermined position in the container unit  21  and engagement of the connectors  79   a  and  79   b  by the closing operation of the door  21   c  of the container unit  21 . Moreover, even an operator with little power can easily carries out accommodation of the heavy powder storing unit  31 , and it is possible to prevent the toppling of the powder storing unit  31 . 
     FIG. 13  shows the internal composition of the powder transport device  20  of this embodiment. 
   As shown in  FIG. 13 , the powder storing part  32  of the powder storing unit  31  is provided with an inclined floor having a V-shaped cross section. The inclination angle of the inclined floor of the powder storing part  32  may be set up to be smaller than the toner resting angle. In this embodiment, the inclination angle is set to about 20 degrees and the toner resting angle is set to about 40 degrees. If the inclination angle of the floor is set to a loose angle, it is possible to make the dead space by inclination small. 
     FIG. 14  shows the composition of the powder storing unit  31 . As shown in  FIG. 14 , a flowable floor (which constitutes an air jet member), including porous members  33 ,  34 ,  35 , and  36 , is provided in the floor of the powder storing part  32  of the powder storing unit  31 . The powder storing part  32  in this embodiment can secure the space adequate for storing a large amount of toner by making the cross-sectional shape into a rectangle. 
   The porous members  33 - 36  are fine porous members that can pass air, and it is desirable that the open area ratio of the porous members  33 - 36  is in a range from 5 to 40%. And it is more desirable that the open area ratio of the porous members  33 - 36  is in a range from 10 to 20%. 
   Moreover, since the volume average particle diameter of the toner commonly used is in a range of 3-15 micrometers, it is desirable that the average opening diameter of the porous members  33 - 36  is in a range of 0.3-20 micrometers. And it is more desirable that the average opening diameter of the porous members  33 - 36  is in a range of 5-15 micrometers. 
   Moreover, it is desirable that the average vacancy diameter of the holes of the porous members  33 - 36  is 0.1 to 5 times as large as the volume average particle diameter of the toner concerned. And it is more desirable that the average vacancy diameter of the holes of the porous members  33 - 36  is 0.5 to 3 times as large as the volume average particle diameter of the toner concerned. As a material of the porous members  33 - 36 , there is no restriction and it can be chosen suitably according to the purpose. 
   For example, the material of the porous members  33 - 36  may be any of a sintered material of glass and resin particles, a photo-etched resin, a porous resin material, such as resin punched thermally, a sintered metal material, a punched sheet-metal material, etc. 
   The air chambers  33   a ,  34   a ,  35   a , and  36   a  connected to the air pump  24  are provided in the lower part of the porous members  33 - 36 . Moreover, the porous members  33 ,  34 ,  35 , and  36  are set up so that the area of the lower porous members  33  and  34  is smaller than that of the upper porous members  35  and  36 . Similarly, the air chambers  33   a ,  34   a ,  35   a , and  36   a  are set up so that the chamber capacity of the lower chambers  33   a  and  34   a  is smaller than that of the upper chambers  35   a  and  36   a.    
   Upon start of operation of the air pump  24 , air is blown off through the air chambers  33   a ,  34   a ,  35   a , and  36   a  from the porous members  33 ,  34 ,  35 , and  36  which are flowable floors and the air is supplied to the toner stored so that the toner is mobilized. And the mobilized toner is attracted by the pump  22  from the toner suction pipe  37  and transported to the toner hopper  9  provided in the image forming unit  1 . At this time, the toner is attracted upwards from near the lowest position of the powder storing part  32 , and most of the toner stored can be attracted and transported. 
   Furthermore, when the toner is attracted upwards, it is transported to the image forming unit  1  which is located at a position higher than the storage position of the powder storing part  32 . For this reason, even when a separation or damage of the transport pipe between the powder transport device  20  and the image forming unit  1  occurs accidentally, it is possible to prevent scattering of the toner in the powder storing part  32 , and it is minimized to scattering of a small amount of toner passed through the transport pipe. 
   As described above, since the capacity of the lower chambers  33   a  and  34   a  is smaller than that of the upper chambers  35   a  and  36   a  and the area of the lower porous members  33  and  34  is smaller than that of the upper porous members  35  and  36 , if an equivalent amount of air is supplied to each air chamber  33   a ,  34   a ,  35   a , and  36   a , the air blown off from the lower porous members  33  and  34  will become more uniform than the air blown off from the upper porous members  35  and  36 . Therefore, the toner attracted with the toner suction pipe  37  can be mobilized certainly. 
   In addition, the sensor which detects the existence of toner is provided near the suction opening of the toner suction pipe  37  as a near-end sensor  38 . Moreover, a filter which prevents the internal pressure in the powder storing part  32  from being increased excessively by the air supplied is provided in the upper part of the powder storing part  32 . 
   If the filter is located above the full-state line of the toner in the powder storing part  32 , the installed position of the filter is not limited to the upper part of the powder storing part  32 . For example, the filter may be disposed at the side part of the powder storing part  32 . The material of the filter may be the same as the material of the porous member. Or, the filter may be made of a sheet of Gore-Tex (brand name, registered trademark) manufactured by Japan Gore-Tex company, which is a continuous porosity structure material made of a fluoro-resin. 
   The toner transported to the toner hopper  9  of the above-mentioned image forming unit  1  from the powder storing part  32  of the powder transport device  20  is transported to the development hopper of the developing device  5  through the transport passage  11 , so that the toner image is formed by the development using the toner supplied. 
   In the powder transport device  20 , the powder storing unit  31  can be removed from the fixed unit  21  and moved. If the toner in the powder storing part  32  becomes empty mostly, the powder storing unit  31  of the powder storing part  32  may be exchanged with a new powder storing unit  31  which is filled up with toner. 
   And the power supply of the powder storing unit  31  is separate from the power supply of the image forming unit  1 , and if toner remains in the image forming unit  1  in part, the powder storing unit  31  may be exchanged with new one, without turning off the power supply of the image forming unit  1 . 
   By the way, several percent of the toner which adhered to the photoconductor  4  by development is not transferred by recording media, such as a decalcomania paper, but remains to the photoconductor  4 . The remains toner is removed by the cleaning device  8 . 
   Moreover, dirt, such as toner adhering to the transfer belt  6 , is removed by the belt cleaning  10 . Conventionally, when it accumulated in the recovery container provided in data processing apparatus by using as waste toner the toner removed by these cleanings and the recovery container filled, operation of machinery is stopped and it is exchanging for a new recovery container. 
   If 30-40 kg of toner shall be stored to the powder storing part  32  of the above-mentioned powder transport device  20  as it is this composition, and about 10% of photoconductor adhering toners shall remain, when the toner is exhausted, about 3-4 kg of waste toner will be collected. 
   Therefore, even if it is about 10 kg with capacity of a recovery container large-sized for the heavy user who consumes about 30 kg of toner in one month, it must exchange every 2 or 3 months, and the work is troublesome. 
   Moreover, enlarging the capacity of the recovery container and reducing exchange frequency may be considered, but the capacity of the recovery container provided in the image forming unit  1  is limited and it is difficult to enlarge the capacity. 
   In this embodiment, the waste toner recovery container  40  which stores waste toner etc. is formed in the powder storing unit  31 , the toner collected in cleaning of the image forming unit  1  is sent to the waste toner recovery container  40 , and the advantage of exchange of the powder storing unit  31  is taken, and it collects. 
   The toner which formed the exhausting part  12  in the image forming unit  1 , and specifically sent the toner removed by the cleaning device  8  through the transport passage  13 , and is removed by the belt cleaning  10  is sent through the transport passage  14 , and is once brought together in the exhausting part  12 . 
   The flowable floor made of the porous member  15  is provided in the floor of the exhausting part  12  like the powder storing part  32 , and air is blown off from the porous member  15  using the air pump  25 . 
   The recovery toner which has little mobility is mobilized by the air blowing off, and it can be easily transported to the powder transport device  20  by the suction of the pump  23 . Since the waste toner recovery container  40  provided in the powder storing unit  31  should just have the amount of recovery determined by the amount of toner accumulated in the tank, the large capacity is unnecessary and there is no need to consider the withstanding strength against the impact from the outside. 
   Therefore, the waste toner recovery container  40  may be made of a flexible resin bag, for example, a plastic bag, etc. 
   Although the waste toner recovery container  40  is attached to the set part  41  with an elastic band etc., the piping  42  into which waste toner is sent, and the filter  43  which extracts air are provided in the set part  41 . 
   Thus, the piping  42  and the filter  43  can be attached to the waste toner recovery container  40  by a single operation because the piping  42  and the filter  43  are provided in the set part  41 . 
   As explained above, the large-scaled powder storing unit  31  is detachably provided to the container unit  21  in this embodiment, and blowing off air from the bottom of the powder storing part  32  through the air jet members (porous members)  35  and  36 , using the pump  22 , and the toner is attracted from the suction opening of the toner suction pipe  37 , and it is breathing out to the toner hopper  9  (the toner receiving unit). 
   And the powder transport device of this embodiment is provided so that, when accommodation of the powder storing unit  31  in the container unit  21  is completed (or when the door  21   c  is closed), the first connector  79   a  and the second connector  79   b  are electrically connected together and transmission of an electric signal or/and a driving current between the powder storing unit  31  and the container unit  21  is allowed. Therefore, it is possible to prevent the toner scattering and the toppling of the powder storing unit and ensure easy exchange work. 
     FIG. 15  is a timing chart for explaining the control process which is performed by the powder transport device in an embodiment of the invention. 
   Similar to the previous embodiment, the powder transport device  20  of this embodiment includes the container unit  21 , and the large-scaled powder storing unit  31  which is detachably attached to the container unit  21 . And blowing off air from the bottom of the powder storing part  32  by the air jet members (porous members)  35  and  36 , using the pump  22 , the toner in the powder storing part  32  is attracted from the suction opening of the toner suction pipe  37 , and supplied to the toner hopper  9  (the toner receiving unit). 
   Similar to the previous embodiment, when accommodation of the powder storing unit  31  in the container unit  21  is completed in this embodiment, the first connector  79   a  and the second connector  79   b  are electrically connected together, and transmission of an electric signal or/and a driving current between the powder storing unit  31  and the container unit  21  can be performed. 
   Specifically, when the powder storing unit  31  is accommodated in the container part of the container unit  21  and the opening of the container unit  21  is closed by the door  21   c , engagement (electrical connection) between the first connector  79   a  provided in the powder storing unit  31  and the second connector  79   b  provided in the door  21   c  is performed. 
   Moreover, similar to the previous embodiment, if the closing of the door  21   c  and the engagement of the first connector  79   a  and the second connector  79   b  are carried out in this embodiment, the door  21   c  is locked by an electronic lock (see  FIG. 10 ) which is interlocked with the engagement of the first connector  79   a  and the second connector  79   b.    
   In addition, the electric signal or/and the driving current which are exchanged between the powder storing unit  31  and the container unit  21  when the first connector  79   a  and the second connector  79   b  are connected electrically, are not limited to those in the previous embodiment (which are the electric signal sent by the motor part and the driving current sent to the motor part). The electric signal or/and the driving current may be any of various signals or currents. For example, when the first connector  79   a  and the second connector  79   b  are connected, an electric signal allowing for the image forming device  1  (or powder transport device  20 ) to detect that the powder storing unit  31  is accommodated in the container unit  21  may also be exchanged. 
   In this embodiment, even when the powder storing unit  31  is accommodated in the container part of the container unit  21 , the powder transport device is controlled so that the toner stored in the powder storing part  32  is not transported to the toner hopper  9  which is the toner receiving unit, if the door  21   c  is opened. 
   Specifically, as shown in  FIG. 15 , the pump  22  is controlled so that operation of the pump  22  is allowed only when the door  21   c  is closed (ON) and the first connector  79   a  and the second connector  79   b  are engaged together. 
   By performing such control, it is possible to avoid the problem that the pump  22  is operated erroneously before the exchange work of the powder storing unit  31  is completed. 
   If the operation of the pump  22  is allowed in response to the toner supply signal transmitted by the image forming device  1 , in the state where the door  21   c  is opened and the transport pipe (tube) which connects the pump  22  and the toner suction pipe  37  is removed in the exchange work of the powder storing unit  31 , the toner will be ejected reversely from the removed transport pipe and scattered, or the toner will be scatters from the clearance of the housing of the toner hopper  9  in which air is fed so much by the pump  22 . 
   To obviate the problem, in this embodiment, when the door  21   c  is opened (OFF) and the first connector  79   a  and the second connector  79   b  are not connected, the operation of the pump  22  is compulsorily stopped irrespective of the presence of a toner supply signal. Thus, it is possible to prevent the above-mentioned problem certainly. 
   Moreover, in this embodiment, the air pump  24  and the air jet members (flowable floor)  35  and  36  are controlled so that the operation of the air jet is allowed irrespective of opening or closing of the door  21   c.    
   Specifically, the air pump  24  for supplying an air jet from the porous members  35  and  36  is controlled so that the operation of the air pump  24  is allowed even when the door  21   c  is opened. In the exchange work of the powder storing unit  31 , the problem, such as toner scattering, does not arise even if the air pump  24  works in the state where the door  21   c  is opened and the transport pipe (tube) which connects the air pump  24  and the air chamber  33   a - 36   a  is removed. Rather, mobilization of the toner in the powder storing part  32  will be promoted more by operating the air pump  24  also when the door  21   c  is opened. 
   As explained above, it is possible for this embodiment to prevent the toner scattering and the toppling of the powder storing container and ensure easy exchange work. 
   In the above-described embodiment, the powder transport device  20  is applied to transport toner to a toner receiving device. It is a matter of course that the powder transport device of the invention is applicable also to transport a 2-component developing agent, containing a toner and a carrier, to a powder receiving device. In this case, a permeability sensor may be used as a detection unit which detects the amount of the remaining 2-component developing agent in the powder storing part  32 . 
   Furthermore, the powder transport device of the invention is applicable to the following powder transport devices: (1) a powder transport device which supplements a resin molding machine with molding material (pellet supplement machine); (2) a powder transport device which transports flour, manure, livestock food, etc.; (3) a powder transport device used at a manufacture spot to transport medicine of powder or fluid, tablets, cosmetics, such as face powder, etc.; (4) a powder transport device which transports cement; (5) a powder transport device which transports a paint for industry which lowers the viscosity by mixing the paint in an air flow; (6) a powder transport device which transports glass beads for industry used for road paint components, filler materials of air beds, etc. 
   In addition, when using powder with high hardness such as a 2-component developing agent, a glass bead, etc., if the porous members (air jet members)  33  (flowable floor) are made of a resin material, such as PE or PC, the porous members may be deformed or damaged with time. And the holes of the porous members may be closed by the deformed or damaged resin members. To obviate the problem, it is desirable to form the air jet members with a fine-mesh metal filter or a sintered material of copper or iron. 
   Moreover, the image forming system of the above-described embodiment may be connected to a LAN, and the amount of the remaining toner in the powder storing unit  31  or the state of the image forming device may be monitored via the network. When such a supervisory system is built, the serviceman can check the use condition of the user&#39;s image forming system, so that the exchange time of the powder storing unit and the abnormalities of the image forming device can be grasped in advance. 
   The present invention is not limited to the above-described embodiments, and variations and modifications may be made without departing from the scope of the present invention. 
   The present application is based on and claims the benefit of priority of Japanese patent application No. 2006-065750, filed on Mar. 10, 2006, and Japanese patent application No. 2006-124698, filed on Apr. 28, 2006, the entire contents of which are hereby incorporated by reference.