Patent Publication Number: US-2013236197-A1

Title: Powder container, toner cartridge, developing device, process unit, image forming apparatus, and method for recycling powder container

Description:
TECHNICAL FIELD 
     The present invention relates to a powder container for housing powder therein, a toner cartridge, a developing device, a process unit, an image forming apparatus, and a method for recycling the powder container. 
     BACKGROUND ART 
     Known is a technique that configures an electrophotographic image forming apparatus such that a detachable component which is a toner cartridge, a developing device, or a process unit in which a toner cartridge, a developing device, a photosensitive element, and the like are integrated is detachably mountable in an image forming apparatus. The image forming apparatus is, for example, a copier, a printer, a facsimile, or a multifunction peripheral (MFP) having multiple functions of these. This technique is advantageous in that a user or the like can perform maintenance of the apparatus easily by replacing the detachable component and adopted by a large number of products because of this advantage. 
     Some type of the detachable component which is a toner cartridge, a developing device, or a process unit includes an information storage medium such as an IC chip (IC tag) on an outer surface of a housing which is a part of the detachable component (see Japanese Patent Application Laid-open No. 2010-276779). Stored in the IC chip serving as the information storage medium is information about a toner amount, driven-rotated time or a driven distance for use in managing wear or degradation of a component such as a developing roller or a photosensitive element resulting from use, the date of manufacture and an identifying number of the detachable component, an identification number of the image forming apparatus in which the detachable component is to be mounted, the date on which the detachable component is mounted, the date on which a usable life of the detachable component has ended, and the like. These pieces of information are stored in the IC chip or updated so that image quality is maintained and a user is informed about when the detachable component needs replacing. 
     Some type of the detachable component includes a toner sensor on the housing for detecting an amount of toner (including toner containing carrier particles) by detecting a pressure change or a magnetic field change. Some type of the toner sensor is an optical toner sensor that includes a light guide member, which is a transparent plastic member arranged in the housing and a part of which is removed to form a blank portion. The optical toner sensor detects toner that is present in the blank portion with light emitted from outside (when toner is present, the light is blocked, while when no toner is present, the light can pass through). 
     Meanwhile, environmental actions are taken globally, notably by developed countries, in recent years. Manufacturers of image forming apparatuses are recycling exhausted detachable components such as toner cartridges, developing devices, and processing units that have become toner depletion as one of the environmental actions. The recycling is performed by collecting the exhausted detachable components from users, performing necessary processes on them, and putting them into the market again. 
     Recycling of the detachable component such as a toner cartridge generally includes a cleaning process that is performed first. The cleaning process includes unsealing a fill port in a housing or boring an additional hole in the housing, and delivering highly-compressed air into the housing through the hole or the fill port using an air gun or the like to discharge residual toner from the housing to the outside. The housing is refilled with toner injected through the fill port or the bored hole. The fill port or the hole is sealed with a seal (see Japanese Patent Application Laid-open No. 2002-251119). 
     However, when an information storage medium such as an IC chip (IC tag) is arranged on the detachable component such as a toner cartridge, the information storage medium can be soiled with toner during the cleaning process as a result that, for example, the toner discharged to the outside of the housing unintentionally sticks to the information storage medium or that an operator unintentionally touches the information storage medium with a hand to which toner is sticking. If the information storage medium is soiled with toner, contact failure can occur at a connection terminal of the information storage medium, resulting in that information cannot be read from or written to the information storage medium accurately. Therefore, in a case where the information storage medium should be soiled with toner, an additional work of cleaning the information storage medium becomes necessary. 
     The same holds true for a toner sensor (hereinafter, “piezoelectric sensor”) that detects a pressure change or a sensor (hereinafter, “magnetic sensor”) that detects a magnetic field change arranged on the detachable component such as a toner cartridge. If the sensor is soiled during cleaning, contact failure can occur at a terminal on the sensor. 
     Furthermore, there can also arise a problem that static electricity generated by air blasting with the air gun during cleaning can damage an electronic component of the information storage medium, the piezoelectric sensor, or the magnetic sensor and make the electronic component unreusable. 
     Meanwhile, unlike the piezoelectric sensor and the magnetic sensor described above, the light guide member of the optical sensor is free from risk of a contact failure. However, the light guide member generally occupies a relatively large space in the housing. Accordingly, the light guide member can hinder cleaning of the housing or toner filling when the light guide member remains attached. 
     Therefore, there is a need for a recycling process of a powder container on which an electronic component or an optical component is arranged and that can be recycled easily and efficiently, a toner cartridge, a developing device, a process unit, an image forming apparatus, each including the powder container, and a method for recycling the powder container. 
     DISCLOSURE OF INVENTION 
     It is an object of the present invention to at least partially solve the problems in the conventional technology. 
     According to an embodiment, there is provided a powder container that includes a housing configured to house powder therein, the housing having a hole connecting between inside and outside of the housing; a cover member detachably attached to the housing to close the hole; and a signal exchanging unit configured to transmit and receive a signal to and from an apparatus to which the powder container is mounted, the signal exchanging unit being provided in the cover member. 
     According to another embodiment, there is provided a toner cartridge that is detachably mounted in an image forming apparatus and includes the powder container according to the above embodiment, the powder being toner. 
     According to still another embodiment, there is provided a developing device that is detachably mounted in an image forming apparatus and includes a powder container according to the above embodiment, the powder being toner; and a developing unit configured to develop a latent image on a latent image carrier using the toner in the powder container. 
     According to still another embodiment, there is provided a process unit that is detachably mounted on an image forming apparatus and includes a latent image carrier configured to carry a latent image thereon; a powder container according to claim  1 , the powder being toner; and a developing unit configured to develop a latent image on the latent image carrier using the toner in the powder container. 
     According to still another embodiment, there is provided an image forming apparatus that includes the powder container according to the above embodiment, the toner cartridge according to the above embodiment, the developing device according to the above embodiment, or the process unit according to the above embodiment. 
     According to still another embodiment, there is provided a method for recycling a powder container that includes a housing configured to house powder therein, the housing having a hole connecting between inside and outside of the housing, a cover member detachably attached to the housing to close the hole, and a signal exchanging unit configured to transmit and receive a signal to and from an apparatus to which the powder container is mounted, the signal exchanging unit being provided in the cover member. The method includes detaching the cover member from the exhausted powder container; cleaning inside the housing; filling the housing with powder through the hole; and closing the hole with the cover member. 
     The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention; 
         FIG. 2  is a schematic configuration diagram of a process unit according to the first embodiment; 
         FIG. 3  is an external view of the process unit; 
         FIG. 4  is an enlarged view of a relevant portion of the process unit; 
         FIG. 5  is another enlarged view of the relevant portion of the process unit; 
         FIG. 6  is a schematic configuration diagram of a process unit according to a second embodiment of the present invention; 
         FIG. 7A  is a side view of a cover member; 
         FIG. 7B  is a view of the cover member as viewed from an inner side; 
         FIG. 8  is a diagram for explaining how to attach the cover member; 
         FIG. 9  is a diagram illustrating the process unit according to the second embodiment in a state where the process unit is mounted in an image forming apparatus; 
         FIG. 10  is a schematic configuration diagram of a process unit according to a third embodiment of the present invention; 
         FIG. 11  is a diagram illustrating the configuration of an optical detector; 
         FIG. 12  is a diagram illustrating a modification of the cover member; 
         FIG. 13  is a schematic configuration diagram illustrating an example where the configuration of the present invention is applied to a process unit for a layout that lays a plurality of process units in a vertically stacked arrangement; and 
         FIG. 14  is a schematic configuration diagram illustrating an example where the configuration of the present invention is applied to a process unit for a layout that lays a plurality of process units in a side-by-side arrangement. 
     
    
    
     BEST MODE(S) FOR CARRYING OUT THE INVENTION 
     Exemplary embodiments of the present invention are described below with reference to the accompanying drawings. In the drawings for describing the present invention, elements such as members or components that are identical in function or shape are indicated by a same reference numeral and/or a symbol as far as they are distinguishable, and repeated description is omitted. 
     First, an overall configuration and operations of an image forming apparatus according to a first embodiment of the present invention are described with reference to  FIG. 1 . 
     An image forming apparatus  1  illustrated in  FIG. 1  is a monochrome-image forming apparatus. A process unit  10  is detachably mounted as an image forming unit on a substantially center portion of the body of the image forming apparatus  1 . The process unit  10  includes a drum-like photosensitive element  2  serving as a latent-image carrier, an electrostatic charging device that includes a charging roller  3  that electrostatically charges a surface of the photosensitive element  2  and the like, a developing device  4  that develops a latent image on the photosensitive element  2  (into a visible image), and a cleaning device including a cleaning blade  5  and the like for cleaning the surface of the photosensitive element  2 . 
     Arranged above the process unit  10  is an exposure device  6  that exposes the surface of the photosensitive element  2 . The exposure device  6  includes a light source, a polygon mirror, an f-theta lens, and a reflection mirror. The exposure device  6  emits laser light L onto the surface of the photosensitive element  2  according to image data. 
     Arranged below the process unit  10  is a transfer device  7  that includes a transfer roller  8  serving as a transfer unit that transfers an image onto a paper sheet or the like. The transfer roller  8  is arranged so as to contact the photosensitive element  2 . A transfer bias voltage is to be applied from a power source (not shown) to the transfer roller  8 . 
     Arranged in a right portion of the image forming apparatus  1  in  FIG. 1  is a sheet feeding device  9  that includes a sheet feeding roller  11  serving as a feeding unit that feeds a sheet recording medium such as a paper sheet or a transparency. 
     Arranged in a left portion of the image forming apparatus  1  in  FIG. 1  are a sheet discharging device  12  including a pair of sheet discharging rollers  13  serving as a discharging unit that discharges a sheet or the like to the outside of the apparatus, and a sheet discharge tray  14  on which sheets or the like discharged to the outside of the apparatus are to be stacked. 
     A conveying path R for conveying a sheet or the like from the sheet feeding device  9  to the sheet discharging device  12  is formed in the image forming apparatus  1 . A conveying device  15  is arranged on the conveying path R at a position upstream of a transfer nip which is provided at a contact portion between the photosensitive element  2  and the transfer roller  8 . The conveying device  15  includes a pair of registration rollers  16  serving as a conveying element that conveys the sheet or the like to the transfer nip at timing appropriate for conveyance. 
     A fixing device  17  is arranged on the conveying path R at a position downstream of the transfer nip. The fixing device  17  includes a fixing roller  18  and a pressing roller  19  arranged in contact with each other. A halogen heater (not shown) serving as a heat source is arranged in the fixing roller  18 . 
     The image forming apparatus  1  operates as described below. 
     When an image forming operation is started, the photosensitive element  2  is rotated clockwise in  FIG. 1 , and the surface of the photosensitive element  2  is uniformly electrostatically charged by the charging roller  3  in predetermined polarity. Subsequently, the exposure device  6  illuminates the charged surface of the photosensitive element  2  with the laser light L according to image data about a document read in by an image reader (not shown). As a result, an electrostatic latent image is formed on the surface of the photosensitive element  2 . The developing device  4  supplies toner onto the electrostatic latent image formed on the photosensitive element  2 . Consequently, the electrostatic latent image is developed into a toner image (visible image). 
     Meanwhile, the sheet feeding roller  11  starts rotating in the sheet feeding device  9  to deliver a sheet to the conveying path R from stacked sheets. The sheet delivered onto the conveying path R abuts on the pair of registration rollers  16  to be temporarily stopped. As a result, skew of the sheet is corrected. Thereafter, the pair of registration rollers  16  is rotated again to convey the sheet to the transfer nip between the photosensitive element  2  and the transfer roller  8  at timing adjusted for the toner image formed on the photosensitive element  2 . 
     At this time, a transfer bias voltage that is opposite in polarity to the polarity in which the toner image on the photosensitive element  2  is charged is applied to the transfer roller  8 . A transfer electric field generated by the transfer bias voltage causes the toner image on the photosensitive element  2  to be transferred onto the sheet. The sheet onto which the toner image is transferred is conveyed to the fixing device  17 . The toner is fused while the sheet passes through a fixing nip where the fixing roller  18  and the pressing roller  19  contact each other. As a result, the toner image is fixed onto the sheet. The sheet is thereafter discharged to the outside of the image forming apparatus  1  by the pair of sheet discharging rollers  13  and stacked on the sheet discharge tray  14 . 
     The surface of the photosensitive element  2  from which the toner image has been transferred is cleaned by the cleaning blade  5  and electrostatically charged again by the charging roller  3  for latent image formation as preparation for a next exposure. 
     Meanwhile, in the first embodiment, the conveying path R for a paper sheet or the like is laid substantially horizontally so that the image forming apparatus  1  can have a thin profile for miniaturization of the apparatus. Furthermore, arranging the conveying path R substantially horizontally makes the image forming apparatus  1  less prone to paper jam with various types of recording media. 
       FIG. 2  is a schematic configuration diagram of the process unit  10 . 
     The developing device  4  included in the process unit  10  is described below with reference to  FIG. 2 . 
     As illustrated in  FIG. 2 , the developing device  4  includes a housing  20 , a developing roller  22 , a supplying roller  23 , a developing blade  24 , and an agitator  25 . The housing  20  internally includes a developer housing unit  21  for housing toner serving as a developer (powder for use in image forming) therein. The developing roller  22  serves as a developing unit that carries toner thereon and develops the latent image on the photosensitive element  2 . The supplying roller  23  serves as a supplying member that supplies toner to the developing roller  22 . The developing blade  24  serves as a restricting member that restricts an amount of toner carried by the developing roller  22 . The agitator  25  serves as an agitating member that stirs the toner in the developer housing unit  21 . 
     The supplying roller  23  is in contact with the developing roller  22 . When the developing roller  22  and the supplying roller  23  start rotating as the image forming operation is started, toner is supplied by the supplying roller  23  onto the surface of the developing roller  22  to be carried thereon. A contact portion between the developing roller  22  and the developing blade  24  restricts a thickness of a layer of the toner carried on the developing roller  22  when the toner layer passes through the contact portion. Thereafter, when the toner on the developing roller  22  is conveyed to a contact portion (developing area) where the toner contacts the photosensitive element  2 , the toner is electrostatically transferred onto the electrostatic latent image on the photosensitive element  2  to form a toner image. The agitator  25  is rotated to thereby stir and simultaneously convey the toner in the developer housing unit  21  toward the supplying roller  23 . 
     As illustrated in  FIG. 2 , a hole  26  that connects between the inside and the outside of the housing  20  is bored in the housing  20 . This hole  26  is provided for toner filling, and closed (sealed) with a plate-like cover member  27  after toner filling. An IC chip (IC tag)  28  serving as the information storage medium is arranged on an outer surface of the cover member  27 . 
     The IC chip  28  stores at least information about the toner housed in the housing  20 . Examples of the information about the toner include a toner amount (remaining amount of the toner) and a color of the toner. Other examples of the information that can be stored in the IC chip  28  include information about driven-rotated time or a driven distance for managing wear or degradation of a component such as the developing roller  22  or the photosensitive element  2  resulting from use, the date of manufacture and an identification number of the process unit  10 , an identification number of the image forming apparatus  1 , the date on which the process unit  10  is mounted, and the date on which a usable life of the process unit  10  has ended. 
     An information reader (not shown) that reads information stored in the IC chip  28  is arranged on the body of the image forming apparatus  1 . Mounting the process unit  10  in the image forming apparatus  1  brings the IC chip  28  on the process unit  10  and the information reader on the image forming apparatus  1  into electrical connection via connecting terminals. As a result, information reading from and information writing to the IC chip  28  becomes possible. 
       FIG. 3  is an external view of the process unit  10 .  FIGS. 4 and 5  are enlarged views of a relevant portion of the process unit  10 . 
     As illustrated in  FIG. 3 , the cover member  27  is detachably attached to the housing  20  via a holder  29  arranged on the outer side of the housing  20 . 
     More specifically, as illustrated in  FIGS. 4 and 5 , the holder  29  has a pair of grooves  29   a  into which the cover member  27  can be inserted. Inserting the cover member  27  into these grooves  29   a  brings a bottom end of the cover member  27  into contact with bottoms  29   b  (see  FIG. 5 ) of the grooves  29   a  so that the cover member  27  is held by the holder  29 . 
     As illustrated in  FIG. 5 , a seal  30  made of polyurethane foam or the like is arranged on a back surface (surface that faces the housing  20 ) of the cover member  27 . This seal  30  is as large as to cover the hole  26 . In a state where the cover member  27  is inserted into the holder  29 , the seal  30  seals the hole  26  to prevent toner leakage through the hole  26 . Furthermore, in this state, the seal  30  is compressed between the cover member  27  and the housing  20 , and a resilience of the compressed seal  30  presses the cover member  27  against the grooves  29   a  of the holder  29 . This pressing force holds the cover member  27  in a manner to prevent the cover member  27  from falling out of the grooves  29   a . The cover member  27  can be detached from the holder  29  by sliding the cover member  27  upward while applying a force greater than the resilience of the seal  30  onto the cover member  27  from an outer side of the cover member  27  toward the housing  20 . 
     A method for recycling the process unit  10  according to the first embodiment is described below. 
     When the process unit  10  has become exhausted because toner is consumed to toner depletion, the exhausted process unit  10  is collected from a user. Thereafter, cleaning for discharging deteriorated residual toner from the housing  20  is performed. Before the cleaning is performed, the cover member  27  on which the IC chip (IC tag)  28  is arranged is detached from the housing  20 . The cover member  27  is stored in such a place where toner scattered during the cleaning will not stick to the cover member  27 . 
     Thereafter, the cleaning of the inside of the housing  20  is performed. The cleaning includes, as a step to be performed first, vibrating the process unit  10  with the hole  26  of the housing  20  facing downward to discharge the residual toner from the housing  20  through the hole  26  to a certain extent. Subsequently, toner still remaining in the housing  20  is blown out through the hole  26  by delivering highly-compressed air into the housing  20  through the hole  26  with an air gun or the like. 
     When the cleaning is completed, the housing  20  is refilled with new toner injected through the hole  26 . The hole  26  is sealed by attaching the stored cover member  27  onto the housing  20 . The information stored in the IC chip  28  is overwritten or partially updated. Recycling of the process unit  10  is completed by performing processes described above. 
     Meanwhile, an approach of boring a new hole in the housing  20  and discharging the residual toner through the new hole can be taken to perform the cleaning of the housing  20 . However, this approach disadvantageously involves careful boring in a manner not to damage internal components and also requires sealing the bored hole. Meanwhile, it is necessary to temporarily disassemble a component from the process unit  10  in a case where highly-compressed air cannot be delivered into the housing  20  through the hole  26  or the like which is provided for toner filling because the air gun interferes with the component. In such a case, preparation for the cleaning requires a considerable amount of work because it becomes necessary to perform not only disassembling the component but also managing the disassembled component. 
     In contrast, in the first embodiment of the present invention, the hole  26  which is provided as the fill port (or a discharge port) in advance is utilized. Accordingly, the cleaning of the inside of the housing  20  can be performed without neither boring a new hole in the housing  20  nor disassembling the process unit  10 . As a result, the cleaning can be performed efficiently. 
     As described above, according to the method for recycling the process unit  10  according to the first embodiment, the cover member  27  on which the IC chip (IC tag)  28  is arranged is detached from the housing  20  and stored before the cleaning of the housing  20  is performed. Accordingly, sticking of scattered toner or toner that has stuck to an operator&#39;s hand to the IC chip (IC tag)  28  during the cleaning is prevented. This eliminates the need of additional cleaning of the IC chip (IC tag)  28  soiled with toner, thereby increasing efficiency of the cleaning. Furthermore, even when a large amount of static electricity is built by air blasting with the air gun during the cleaning, the IC chip (IC tag)  28  is unaffected by the static electricity and therefore will not become damaged. This allows reuse of the IC chip (IC tag)  28  and leads to reduction in recycling cost. 
       FIG. 6  is a schematic configuration diagram of a process unit  100  according to a second embodiment of the present invention. 
     Only portions of the configuration of the process unit  100  according to the second embodiment that differ from those of the first embodiment are described below. 
     The process unit  10  according to the first embodiment includes the IC chip (IC tag)  28  that provides information about presence/absence (remaining amount) of toner in the housing. In contrast, the process unit  100  according to the second embodiment illustrated in  FIG. 6  includes a piezoelectric sensor  31  as a detector that detects presence/absence (remaining amount) of toner. The piezoelectric sensor  31  is arranged in a housing  120  of the process unit  100  and detects whether toner is present in the housing  120  based on a load of toner imposed on an end surface of the piezoelectric sensor  31 . 
     The piezoelectric sensor  31  is arranged on the inner surface of a cover member  127  that is detachably attachable to the housing  120 . As illustrated in  FIG. 6 , the piezoelectric sensor  31  is exposed to the inside of the housing  120  through a hole  126  bored in the housing  120  in a state where the cover member  127  is attached to the housing  120 . This hole  126  also functions as the hole for cleaning of the housing  120  and toner filling. 
       FIG. 7A  is a side view of the cover member  127  illustrated in  FIG. 6 .  FIG. 7B  is a view of the cover member  127  as viewed from the internal side. 
     As illustrated in  FIGS. 7A and 7B , the piezoelectric sensor  31  is attached to the inner surface of the cover member  127  via an IC substrate  32 . A plurality of slits  33  are provided in the cover member  127  at a portion where the IC substrate  32  is attached. An electrical contact on the IC substrate  32  is exposed to the outside through the slits  33 . A screw hole  34  is bored in each of longitudinally opposite end portions of the cover member  127 . 
     As illustrated in  FIG. 8 , the cover member  127  is attached to the housing  120  by inserting screws  35  into the screw holes  34  in the cover member  127 , and tightening the screws  35  into screw holes  36  in the housing  120 . The seal  130  made of a sponge or the like is arranged around the hole  126  bored in the housing  120 . When the cover member  127  is attached to the housing  120 , the cover member  127  and the seal  130  seal the hole  126 . As a result, toner leakage through the hole  126  is prevented. 
       FIG. 9  is a diagram illustrating the process unit  100  according to the second embodiment illustrated in  FIG. 6  in a state where the process unit  100  is mounted in the image forming apparatus  1 . 
     As illustrated in  FIG. 9 , mounting the process unit  100  in the image forming apparatus  1  brings the electrical contact on the IC substrate  32  into contact with an electrical contact  37  on the body of the image forming apparatus  1 , thereby electrically connecting the piezoelectric sensor  31  to a CPU  38  in the image forming apparatus  1 . In this example, the electrical contact  37  on the body of the image forming apparatus  1  is made up of three flat springs and contacts the electrical contact on the IC substrate  32  through the slits  33  provided in the cover member  127 . When electrical connection is established between the piezoelectric sensor  31  and the CPU  38 , the CPU  38  can receive an electrical signal output from the piezoelectric sensor  31 . The CPU  38  determines presence or absence of toner based on the electrical signal. When the CPU  38  determines that there is no toner, a notifying element (not shown) issues a notifying signal according to an instruction fed from the CPU  38 . 
     Subsequently, a method for recycling the process unit  100  according to the second embodiment illustrated in  FIG. 6  is described below. 
     The process unit  100  is to be recycled as follows. First, as with the recycling method described above, the cover member  127  is detached from the housing  120  and stored. After cleaning of the inside of the housing  120 , the housing  120  is refilled with new toner injected through the hole  126 . The hole  126  is sealed by attaching the cover member  127  onto the housing  120 . 
     Also in this recycling, the cover member  127  is detached from the housing  120  and stored before the cleaning of the housing  120  is performed. Accordingly, sticking of toner to the piezoelectric sensor  31  during the cleaning is prevented. This eliminates the need of additional cleaning of the piezoelectric sensor  31  soiled with toner, thereby increasing efficiency in the cleaning. Furthermore, even when a large amount of static electricity is built by air blasting with an air gun during the cleaning, the piezoelectric sensor  31  is unaffected by the static electricity and therefore will not become damaged. This allows reuse of the piezoelectric sensor  31  and leads to reduction in recycling cost. 
     In the configuration illustrated in  FIG. 6 , a magnetic sensor may be arranged on the cover member  127  as the detector for detecting presence/absence of toner in lieu of the piezoelectric sensor  31 . Among magnetic sensors, a magnetic sensor that detects a two-component developer made up of a carrier and toner is capable of detecting a toner concentration in addition to detecting presence/absence of toner. Also in this case, toner sticking to the magnetic sensor or a damage to the magnetic sensor by static electricity built during the cleaning of the housing  120  can be prevented by arranging the magnetic sensor on the cover member  127  as in the case where the piezoelectric sensor is used. 
       FIG. 10  is a schematic configuration diagram of a process unit  200  according to a third embodiment of the present invention. 
     Only portions of the configuration of the process unit  200  according to the third embodiment that differ from those of the first and second embodiments are described below. 
     In the third embodiment, an optical detector is used as the detector that detects presence/absence (remaining amount) of toner. 
     As illustrated in  FIG. 11 , an optical detector  40  includes a light-emitting element  41  for emitting light, a light-receiving element  42  for receiving light, and a first light guide member  43  and a second light guide member  44  for guiding the light emitted from the light-emitting element  41  to the light-receiving element  42 . The light guide members  43  and  44  are made of a transparent plastic or the like and arranged on a cover member  227  that is detachably attachable to a housing  220 . The light-emitting element  41  and the light-receiving element  42  are arranged in the image forming apparatus  1 . As illustrated in  FIG. 10 , the image forming apparatus  1  includes a driver  45  that causes the light-emitting element  41  to emit light at regular intervals and a CPU  46  that determines presence/absence of toner based on an output value of the light-receiving element  42 . 
     A hole  226  is bored in the housing  220  at a portion where the cover member  227  is to be attached. As illustrated in  FIG. 10 , the light guide members  43  and  44  are arranged in the housing  220  through the hole  226  in the state where the cover member  227  is attached to the housing  220 . As in the case of the first and second embodiments, this hole  226  also functions as the hole for cleaning of the housing  220  and toner filling. 
     As illustrated in  FIG. 11 , an externally-exposed end portion of the light guide member  43  and that of the light guide member  44  face the light-emitting element  41  and the light-receiving element  42 , respectively, in the state where the process unit  200  is mounted in the image forming apparatus  1 . In this state, light emitted from the light-emitting element  41  enters an end  43   a  of the first light guide member  43  and exits from another end  43   b  on the other side of the first light guide member  43  as illustrated in  FIG. 11 . The light that exits the end  43   b  of the first light guide member  43  enters an end  44   a , which faces the end  43   b , of the second light guide member  44  and exits from another end  44   b  on the opposite side of the second light guide member  44  to reach the light-receiving element  42 . 
     When the amount of toner in the housing  220  is sufficient, toner present between the ends  43   b  and  44   a  that face each other of the first light guide member  43  and the second light guide member  44  blocks light. Therefore, light does not reach the light-receiving element  42 . On the other hand, when toner is consumed for printing or the like and a toner level has dropped to be lower than the position of the light guide members  43  and  44 , toner is no more present between the ends  43   b  and  44   a  that face each other of the first light guide member  43  and the second light guide member  44 . Therefore, light reaches the light-receiving element  42 . When the CPU  46  receives a signal (output value) output from the light-receiving element  42  in this state, the CPU  46  determines that the toner amount is below a predetermined amount. When the CPU  46  has determined that the toner amount is below the predetermined amount, a notifying element (not shown) issues a notification about low toner. 
     In the third embodiment illustrated in  FIG. 10 , an agitator  225  rotates such that a portion of the agitator  225  periodically passes through a clearance between the ends  43   b  and  44   a  that face each other of the first light guide member  43  and the second light guide member  44  to push out toner present between the ends  43   b  and  44   a . A developing device  204  illustrated in  FIG. 10  is a developing device that adopts a vertically-stacking layout in which the developer housing unit  21  is arranged above the developing roller  22  and the supplying roller  23 . A partition  47  divides the developing device  204  into a developing unit  48  in a lower portion and the developer housing unit  21  in an upper portion. The toner housed in the developer housing unit  21  is stirred and delivered to a screw conveyor  49  by the agitator  225 . The toner is further conveyed by the rotating screw conveyor  49  toward an axial end of the developer housing unit  21  to be supplied to the developing section  48  through a hole  47   a  bored in the partition  47 . 
     Similarly to the cover member  127  illustrated in  FIG. 8 , a cover member  227  illustrated in  FIG. 11  has the screw holes  234  for screw fastening. The seal  130  made of a sponge or the like is arranged around the hole  226  bored in the housing  220  (see  FIG. 8 ) as in the case of the embodiments described above. 
     Subsequently, a method for recycling the process unit  200  according to the third embodiment illustrated in  FIG. 10  is described below. 
     The process unit  200  according to the third embodiment is to be recycled fundamentally in a manner similar to those of the first and second embodiments. More specifically, after detaching the cover member  227  from the housing  220  and storing the cover member  227 , cleaning of the inside of the housing  220  is performed. Thereafter, the housing  220  is refilled with new toner injected through the hole  226 , and the cover member  227  is attached to seal the hole  226 . 
     According to this method, the cover member  227  is detached from the housing  220  before the cleaning of the housing  220  is performed so that the light guide members  43  and  44  temporarily evacuate from the inside of the housing  220 . As a result, such a situation that the light guide members  43  and  44  hinder the cleaning and toner filling that follows the cleaning is prevented. The cleaning and the toner filling are therefore facilitated. 
       FIG. 12  illustrates a modification of the cover member. 
     A cover member  327  illustrated in  FIG. 12  includes a cylindrical insertion portion  327   a  that is to be inserted into a circular hole (not shown) bored in the housing  220  and a flange portion  327   b  arranged on a rim of the insertion portion  327   a . The cover member  327  is made of a soft material such as polypropylene. When the cover member  327  is attached to the housing  220 , the insertion portion  327   a  is press-fit into the hole to thereby seal the hole  226 . Therefore, this modification eliminates the need of arranging a seal around the hole  226 . 
     Indicated by reference numeral  50  in  FIG. 12  is a support member that is arranged on the cover member  327  to prevent tilt of the light guide members  43  and  44 .  FIG. 12  illustrates the configuration in which the light guide members  43  and  44  are arranged on the cover member  327  made of a soft material. Alternatively, the IC chip (IC tag), the piezoelectric sensor, the magnetic sensor, or the like can be arranged on the cover member  327  similar to that illustrated in  FIG. 12 . The insertion portion  327   a  can have a shape other than the circular shape depending on a shape of the hole into which the insertion portion  327   a  is to be inserted. 
     It should be understood that the present invention is not limited to the embodiments discussed above, and various modifications can be made within the scope of the present invention. The embodiments have been described by way of the examples in each of which the configuration of the present invention is applied to the process unit to be mounted on the monochrome-image forming apparatus illustrated in  FIG. 1 . However, the configuration of the present invention is also applicable to a process unit to be mounted on a printer, a copier, a facsimile, or an MFP having multiple functions of these. 
       FIGS. 13 and 14  illustrate examples in each of which the configuration of the present invention is applied to a process unit for a color-image forming apparatus. 
     Illustrated in  FIG. 13  is a process unit  400  for a layout that lays a plurality of process units in a vertically stacked arrangement (vertical arrangement). Illustrated in  FIG. 14  is a process unit  500  for a layout that lays a plurality of process units in a side-by-side arrangement (horizontal arrangement). 
     The process unit  400  illustrated in  FIG. 13  and the process unit  500  illustrated in  FIG. 14  can also yield operation advantage similar to that of the embodiments when the IC chip (IC tag)  28 , or an electronic component (a piezoelectric sensor, a magnetic sensor, or the like) or an optical component (a light guide member or the like) that forms the various types of detector for detecting presence/absence of toner is arranged on the cover member  27  that is detachably attached to respective housings  420  and  520 . 
     Application of the configuration of the present invention is not limited to the process units  10 ,  100 ,  200 ,  400 , and  500  into which the photosensitive element  2 , the developing device  4 , and the like are combined. The configuration is also applicable to the developing device  4  that is separated from the photosensitive element  2 , and a toner cartridge which is the developer housing unit  21  (toner container) and the like separated from the developing device  4 . 
     More specifically, referring to  FIG. 2 , the developing device  4  can be configured to be singly detachably attachable to the image forming apparatus  1 . This can be achieved by separating from the developing device  4  a photosensitive element unit into which the photosensitive element  2 , the electrostatic charging unit that includes the charging roller  3 , and the cleaning device that includes the cleaning blade  5  are combined. Alternatively, the developer housing unit  21  (toner container) and the agitator  25  can be separated from among the constituents of the developing device  4  illustrated in  FIG. 2  to form a toner cartridge which is independent of the developing device  4 . The toner cartridge can be configured to be singly detachably attachable to the image forming apparatus  1 . In each of these cases, the developing device  4  or the toner cartridge is to be singly detached and recycled in a manner similar to those described above. 
     Application of the configuration of the present invention is not limited to the toner cartridge for housing toner therein, the developing device, and the process unit. The configuration is also applicable to a powder container that houses powder other than toner in its housing. More specifically, when a powder container that is to be mounted in an apparatus and includes an electronic or optical component that performs its function by exchanging an electrical or optical signal with the apparatus, operation advantage similar to that described above can be obtained by configuring the electronic or optical component to be detachably attachable in one piece with a cover member. 
     According to the embodiments, even when a powder container includes an electronic component such as an IC chip (IC tag), a piezoelectric sensor, or a magnetic sensor, sticking of powder or the like to the electronic component during cleaning of the housing can be prevented by detaching the electronic component in one piece with the cover member and storing it before the cleaning. This eliminates the need of additional cleaning of the electronic component soiled with powder or the like, thereby increasing efficiency in the cleaning. Furthermore, even when static electricity is built during the cleaning, the electronic component is unaffected by the static electricity and therefore will not become damaged. Accordingly, recycling can be performed efficiently. 
     Even when the powder container includes an optical component such as a light guide member, detaching the optical component in one piece with the cover member before cleaning of the housing is performed prevents the optical component from hindering the cleaning of the housing and powder filling, and therefore the cleaning and the powder filling are facilitated. As a result, efficiency in the cleaning and the powder filling is increased. 
     Thus, according to the embodiments, the electronic component or the optical component is detachable in one piece with the cover member from the housing. This enables easy and efficient recycling of the powder container. 
     Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.