Patent Publication Number: US-7596327-B2

Title: Developing cartridge and image forming apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority from Japanese Patent Application No. 2005-282341, filed on Sep. 28, 2005, the entire subject matter of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     Aspects of the present invention relate to a developing cartridge equipped with an agitation member and an image forming apparatus. 
     BACKGROUND 
     Heretofore, an image forming apparatus such as a laser printer, to which a developing cartridge containing a developer (hereafter referred to as a toner) can be detachably attached, has been known. Normally, the developing cartridge is equipped, in a developer container for containing the toner, with an agitation member (hereafter referred to as an agitator) for agitating the toner and supplying the toner to a developer carrier (hereafter referred to as a developing roller). 
     The agitator includes a rotary shaft and a plate-like agitation portion projecting from the rotary shaft in a direction perpendicular to the rotary shaft. 
     Both ends of the rotary shaft are rotatably supported on a developing cartridge casing sidewall forming the developer container. Particularly, one end of the rotary shaft is provided in such a way as to pass through the casing sidewall, and a drive member (hereafter referred to as a gear) for transmitting a driving force to the rotary shaft is fixed to the pass-through portion. 
     Also, the gear is provided with a detected portion for causing a detector portion disposed in an image forming apparatus to detect a rotary condition of the rotary shaft (for example, refer to JP-A-2004-191559). 
     In the thus configured developing cartridge, by the rotary shaft and thus the agitation portion of the agitator rotating in response to a driving force from the image forming apparatus via the gear, the toner in the developer container is agitated and supplied to the developing roller. Furthermore, the rotary condition of the rotary shaft is detected by the detector portion via the detected portion. 
     SUMMARY 
     Meanwhile, in such a developing cartridge and image forming apparatus, in the event that they are kept in the same condition for a long period of time, the toner contained in the developer container may coagulate. When the agitator is activated with the toner coagulated in this way, the agitation portion undergoes a large resistance, whereby a large load is applied to a portion provided with the gear of the rotary shaft (hereafter referred to as a gear installation portion) and, in some cases, the rotary shaft of the agitator is broken in the vicinity of the gear installation portion (as used herein, the breaking, including a fracture of the rotary shaft, refers to a condition in which the rotary shaft cannot rotate normally). 
     Then, in the event that the rotary shaft of the agitator is thus broken and the agitation portion does not function adequately, a supply of the toner to a supply roller and thus the developing roller becomes insufficient or unstable, giving rise to a factor which causes a defective printing. 
     However, in the apparatus disclosed in JP-A-2004-191559, even though an abnormality occurs in which the rotary shaft of the agitator is broken, the gear provided with the detected portion, in response to the driving force supplied from the image forming apparatus, continues to rotate regardless of an operation of the agitation portion. Therefore, there is a problem in which it is impossible to cause the detector portion of the image forming apparatus to detect such an abnormality. 
     Aspects of the invention provide a developing cartridge and an image forming apparatus, which can reliably detect a breaking of an agitator. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view showing an outline of an image forming apparatus; 
         FIG. 2  is an enlarged view of a developing cartridge; 
         FIG. 3  is a sectional view taken along line X-X of  FIG. 2 ; 
         FIG. 4  is a perspective view showing a configuration of a detected portion and a detector portion; 
         FIG. 5  is a configuration view showing a drive member; 
         FIG. 6  is a block diagram showing a configuration of a controller; 
         FIG. 7  is a flowchart of a printing process; 
         FIG. 8  is a flowchart of a stop process; 
         FIG. 9  is a flowchart of a setting change process; 
         FIGS. 10A to 10C  are illustrations showing shapes of a notch; 
         FIGS. 11A to 11C  are illustrations of pulse waveforms; 
         FIG. 12  is a sectional view showing an outline of a color laser printer; 
         FIG. 13  is a flowchart of an attachment position determination process; 
         FIGS. 14A to 14D  are illustrations of pulse waveforms differing according to a toner color; and 
         FIG. 15  is a perspective view showing a modified example of the detected portion. 
     
    
    
     DETAILED DESCRIPTION 
     [General Overview] 
     According to a first aspect of the invention, there is provided a developing cartridge comprising: a developer container that contains a developer; a developer carrier that carries the developer; an agitation member that comprises a rotary shaft, agitates the developer in the developer container and supplies the developer to the developer carrier; a drive member that is provided at one end of the rotary shaft and transmits a driving force to the rotary shaft; and a detected portion that is provided at the other end of the rotary shaft. 
     In the thus configured developing cartridge, in a case in which the rotary shaft rotates normally, the detector portion, via the detected portion, detects the rotary condition of the rotary shaft synchronized with an operating condition of the drive member. 
     However, in the event that the rotary shaft of the agitation member is broken on an attachment end side of the drive member (the breaking, including a fracture of the rotary shaft, refers to a condition in which the rotary shaft cannot rotate normally), the driving force from the drive member is not transmitted to an installation end side of the detected portion, and the detected portion is placed in a different operating condition from that of the drive member, such as a condition in which the detected portion stops operating. 
     Consequently, according to the developing cartridge, by comparing the drive condition of the drive member and the operating condition of the detected portion, it is possible to reliably detect the breaking of the agitation member. 
     According to a second aspect of the invention, the developing cartridge is configured to be installed in an image forming apparatus comprising a detector, and wherein the detected portion is detected by the detector when the developing cartridge is installed in the image forming apparatus. 
     Also, according to a third aspect of the invention, the detected portion is a rotary member that is rotated by a rotation of the rotary shaft. 
     According to the thus configured developing cartridge, even without converting the rotary movement of the rotary shaft into another movement (for example, a reciprocating movement), it is possible to detect the rotary condition of the rotary shaft (that is, the breaking of the agitation member). Consequently, a structure of the detected portion can be simplified. 
     Furthermore, according to a fourth aspect of the invention, the detected portion is integrally formed with the rotary shaft. 
     According to the thus configured developing cartridge, as the rotation of the rotary shaft is directly transmitted to the detected portion, it is possible to more reliably detect the breaking of the agitation member. 
     As used herein, the integral formation includes both a configuration in which the detected portion molded separately from the rotary shaft is directly connected to the rotary shaft and a configuration in which the rotary shaft and the detected portion are integrally molded. 
     Next, according to a fifth aspect of the invention, the detected portion comprises a phase information provision portion that contributes to detect that a rotation phase of the rotary shaft falls in a preset reference phase. 
     According to the thus configured developing cartridge, information (that is, the reference phase) for specifying the rotation phase of the rotary shaft and thus the position of the agitation portion can be provided to an exterior (that is, the image forming apparatus) via the detected portion. 
     Then, according to the image forming apparatus having attached thereto the developing cartridge, by controlling the drive of the drive member based on a result of the detection in the detector portion, the agitation portion etc. of the agitation member can be stopped in an appropriate position (for example, a position which does not remain under a pressure from the developer). 
     Also, according to a sixth aspect of the invention, the detected portion comprises a loading amount information provision portion that contributes to detect detection signals differing according to an initial loading amount of the developer contained in the developer container 
     According to the thus configured developing cartridge, information on the initial loading amount of the developer contained in the developer container can be provided to the exterior (that is, the image forming apparatus) via the detected portion. 
     Then, according to the image forming apparatus having attached thereto the developing cartridge, it becomes possible, based on the detection result from the detector portion, to identify a type (that is, the initial loading amount of the developer) of the developing cartridge attached to the image forming apparatus. 
     It is also acceptable that the loading information provision portion is one combined with the phase information provision portion of the fourth aspect. 
     Also, according to a seventh aspect of the invention, the detected portion comprises a type information provision portion that contributes to detect detection signals differing according to a type of the developer contained in the developer container 
     According to the thus configured developing cartridge, information on the type of the developer contained in the developer container can be provided to the exterior (that is, the image forming apparatus) via the detected portion. 
     It is also acceptable that the type information provision portion is one combined with either or both of the phase information provision portion of claim  4  and the loading information provision portion of the fifth aspect. 
     Next, according to an eighth aspect of the invention, there is provided an image forming apparatus comprising: a developing cartridge that comprises: a developer container that contains a developer; a developer carrier that carries the developer; an agitation member that comprises a rotary shaft, agitates the developer in the developer container and supplies the developer to the developer carrier; a drive member that is provided at one end of the rotary shaft and transmits a driving force to the rotary shaft; and a detected portion that is provided at the other end of the rotary shaft; a drive section that supplies the driving force to the drive member; a detector portion that detects a rotary condition of the rotary shaft via the detected portion; and a drive control section that controls an operation of the drive section when forming an image and comprises an abnormal stop section that stops the drive section if the operation of the drive section does not match with a result of the detection by the detector portion. 
     According to the thus configured image forming apparatus, the drive section can be prevented from remaining in operation (as used herein, the operation includes a roller drive which is carried out for a printing) with the rotary shaft of the agitation member being broken, making it possible to suppress an occurrence of a defective printing. 
     Meanwhile, in a case of a normal operation stop, when the agitation member is stopped in a position in which the agitation portion of the agitation member makes contact with the developer, the agitation member being stopped is deformed by remaining under the pressure from the developer, and may become unable to fulfill its own role. 
     In order to solve such a problem, according to a ninth aspect of the invention, the detected portion comprises a phase information provision portion that causes the detector portion to detect that a rotary phase of the rotary shaft falls in a preset reference phase, and the drive control section comprises a stop control section that, when stopping the operation of the drive section, stops the agitation member in a preset stop position by controlling the drive section based on the result of the detection by the detector portion in such a way that the rotary shaft stops at a stop phase having a predetermined relationship with the reference phase. 
     According to the thus configured image forming apparatus, as an unnecessary pressure is prevented from remaining applied to the agitation member being stopped, this member can be prevented from being deformed and, as a result, a useful life of the agitation member can be increased. 
     Also, according to a tenth aspect of the invention, the developing cartridge has a loading hole that is for loading the developing cartridge with the developer and is provided on an end side of the rotary shaft of the agitation member, and the stop position is set outside an opening area of the loading hole in a direction along the rotary shaft of the agitation member. 
     According to the thus configured image forming apparatus, as a loading nozzle can be smoothly inserted via the loading hole, a replenishment of the developer can be easily carried out. 
     Next, according to an eleventh aspect of the invention, the detected portion comprises a loading amount information provision portion that causes the detector portion to detect detection signals differing according to an initial loading amount of the developer contained in the developer container, and the image forming apparatus further comprises a use detection section that detects whether or not the developing cartridge is unused and a use period setting unit that, if a result of the detection by the use detection section is that the developing cartridge is unused, sets information on a use period of an attached developing cartridge in accordance with a pattern of the detection signal detected by the detector portion. 
     According to the thus configured image forming apparatus, the use period of the developing cartridge can be set according to the type of the developing cartridge (for example, a cartridge before shipment, a replacement cartridge or the like). As a result, a printing using a deteriorated developer can be prevented, making it possible to suppress a defective printing. 
     The use period refers to a period of time for which the developer can be used without any deterioration. Also, as information on the use period, specifically, it is possible to employ the number of revolutions of the rotary shaft (that is, the agitation portion), the number of copies printed in the image forming apparatus, or the like. 
     Also, according to a twelfth aspect of the invention, the detected portion comprises a type information provision portion that causes the detector portion to detect detection signals differing according to a type of the developer contained in the developer container, and the image forming apparatus further comprises a plurality of cartridge attaching portions which is provided according to the type of the developer and to each of which a developing cartridge is attached and an attachment position determination section that, in accordance with the pattern of the detection signal detected by the detector portion, determines whether or not the developing cartridge attached to the cartridge attaching portion is in an appropriate position. 
     According to the thus configured image forming apparatus, in the event that the developing cartridge is attached in an inappropriate position as a result of the determination by the attachment position determination means, by executing an inhibition of a printing process, an alarm process for a user, or the like, it is possible to prevent an abnormal printing execution based on an inappropriate attachment of the developing cartridge. 
     Also, according to a thirteenth aspect of the invention, the detector portion is used in a condition of non-contact with the detected portion. 
     With the thus configured image forming apparatus of the invention, the useful life of the detector portion can be lengthened. 
     Furthermore, according to a fourteenth aspect of the invention, a space on a movement path along which the detected portion moves when the developing cartridge is attached and detached is defined as a detected portion movement path, wherein the detector portion is disposed outside the detected portion movement path. 
     With the thus configured image forming apparatus, the developing cartridge can be easily attached to and detached from the image forming apparatus. 
     [One Aspect] 
     &lt;Overall Configuration of Apparatus&gt; 
     Aspects of the invention will hereafter be described with reference to the drawings. 
       FIG. 1  is a sectional view showing a schematic configuration of a laser printer  1 , which is an image forming apparatus. 
     The laser printer  1  shown in  FIG. 1  is equipped, at a bottom of a body casing  2 , with a feeder unit  15  which feeds sheets of paper (not shown). The feeder unit  15 , being equipped with a paper pressing plate  10  which is pressed by a not-shown spring, a paper feed roller  11  and a friction separation member  14 , causes the paper pressing plate  10  to press the sheets of paper against the paper feed roller  11  and, between the paper feed roller  11  and the friction separation member  14 , separates one sheet of paper from the others as the paper feed roller  11  rotates, thereby carrying out a paper feeding at a prescribed timing. 
     A pair of register rollers  12  and  13 , being rotatably supported on a downstream side in a paper conveying direction of the paper feed roller  11 , which rotates in a direction of the arrow in  FIG. 1 , conveys the sheet of paper at a prescribed timing to a transfer position between a photosensitive drum  20  and a transfer roller  21 . 
     Also, an image forming section is equipped with a scanner unit  40 , a process cartridge  6 , a fixing unit  70  and the like. 
     Of them, the scanner unit  40  is equipped with a laser diode which is a light emitting element which emits a laser beam for forming an electrostatic latent image on the photosensitive drum  20 , a polygon mirror  41  which is rotationally driven, an fθ lens  42  for focusing the laser beam, a toric lens  45 , and reflecting lenses  43 ,  44  and  46 . That is, the scanner unit  40  is configured in such a way that a laser beam which, being based on image data, is emitted from the laser diode, is deflected by the polygon mirror  41  then, after passing through the fθ lens  42 , has an optical path changed by the reflecting mirrors  43  and  44  and, furthermore, after passing through the toric lens  45 , has the optical path bent downward by the reflecting mirror  46 , thereby being projected onto a surface of the photosensitive drum  20  by a high speed scanning. 
     The process cartridge  6 , which is a cartridge having a configuration for carrying out an image forming process (charging, developing, transferring and cleaning (cleaning of a photosensitive drum)), below the scanner unit  40 , is detachably attached to the body casing  2 . The process cartridge  6  includes a drum cartridge  5  and a developing cartridge  50  which is a developing device and is detachably attached to the inner side of the drum cartridge  5 . 
     The drum cartridge  5 , having a configuration which allows the developing cartridge  50  to be attached thereto and detached therefrom, is configured in such a way that the photosensitive drum  20 , a charger  30  and the transfer roller  21  are incorporated therein. 
     The photosensitive drum  20  to be irradiated with the laser beam, being made of an organic photosensitive containing mainly, for example, a positively chargeable polycarbonate, is rotatably supported on the body casing  2 . The photosensitive drum  20 , by having a driving force applied to a drive member (not shown) thereof, is rotatably driven in a direction of the arrow in  FIG. 1 . 
     The charger  30  is configured in such a way as to charge the photosensitive drum  20  by generating a corona discharge from a charging wire made of, for example, tungsten. 
     The transfer roller  21 , including a conductive foamed elastic body made of silicon rubber, urethane rubber or the like, is rotatably supported. The transfer roller  21  is configured in such a way as to transfer a toner image on the photosensitive drum  20  to the sheet of paper as a voltage is applied to the transfer roller  21 . 
     The fixing unit  70 , being provided on a downstream side in the paper conveying direction of a pressure-contact portion between the photosensitive drum  20  and the transfer roller  21 , is equipped with a heating roller  71  and a pressing roller  72 . The toner image transferred to the sheet of paper, while being conveyed by the heating roller  71  and the pressing roller  72 , is heated, pressed, and thereby fixed to the sheet of paper. 
     Also, a pair of conveying rollers  73  and a pair of paper discharge rollers  74 , which are disposed for use in paper conveyance, are provided on a downstream side of the fixing unit  70  in the conveying direction, and a paper discharge tray  75  is provided on a downstream side of the paper discharge rollers  74 . 
     The body casing  2  and the developing cartridge  50  are provided with a developer remaining amount detection mechanism described later for detecting a remaining amount of developer. As shown in  FIG. 3 , the developer remaining amount detection mechanism includes a sensor made up of a remaining amount detection light emitting portion  60  and a remaining amount detection light receiving portion  61  which are provided on the body casing  2 , a light transmission window  56  provided in the developing cartridge  50 , and an opening  62  provided in the drum cartridge  5 . 
     The light transmission window  56 , being a transparent or half transparent member formed from an acrylic resin or the like, includes a light transmission window  56   a  attached to a casing end wall  51   a  on the remaining amount detection light emitting portion  60  side of a casing  51 , and a light transmission window  56   b  attached to a casing end wall  51   b  on the remaining amount detection light receiving portion  61  side. Furthermore, openings  62   a  and  62   b  are formed in positions corresponding to the light transmission windows  56   a  and  56   b  of the drum cartridge  5 , and the remaining amount detection light emitting portion  60  and the remaining amount detection light receiving portion  61  are provided on both sides of the developing cartridge  50  in such a way as to correspond to positions in which the light transmission windows  56   a  and  56   b  are provided. 
     The remaining amount detection light emitting portion  60  includes a holder  60   a  attached to a frame  2   b  of the body casing  2 , a substrate  60   b  supported on the holder  60   a , and a light emitting element  60   c  provided on the substrate  60   b . The holder  60   a  is formed from plastics, and aplastic lens  60   d  is formed by integral molding on a side of the holder  60   a  opposite the light transmission window  56   a . A light emitting diode is employed as an example of the light emitting element  60   c.    
     Also, as with the remaining amount detection light emitting portion  60 , the remaining amount detection light receiving portion  61  includes a holder  61   a , a substrate  61   b  and a light receiving element  61   c  provided on the substrate  61   b . A phototransistor is employed as an example of the light receiving element  61   c.    
     The heretofore described light emitting element  60   c , plastic lens  60   d , opening  62   a  of the drum cartridge  5 , light transmission window  56   a , light transmission window  56   b , opening  62   b  of the drum cartridge  5 , plastic lens  61   d  and light receiving element  61   c , as shown in  FIG. 3 , are arranged on a substantially straight line, and are disposed in a position which does not overlap a detected portion  94  of a rotary shaft  55  to be described hereafter. 
     Consequently, in a condition in which no toner exists between the light transmission window  56   a  and the light transmission window  56   b , the light emitting element  60   c  emits light, and the light transmitted through the light transmission window  56   a  is made incident on the light transmission window  56   b  on the opposite side and received by the light receiving element  61   c . That is, the light receiving element  61   c  receives a light quantity corresponding to a remaining amount of toner. 
     &lt;Configuration of Developing Cartridge&gt; 
       FIG. 2  is an enlarged view showing in enlarged form a portion of the developing cartridge  50 , and  FIG. 3  is a sectional view taken along line X-X of  FIG. 2 . 
     As shown in  FIGS. 2 and 3 , the developing cartridge  50  is equipped, in its casing  51 , with a developer container  52  containing a toner (not shown), which is a nonmagnetic developer, and a developing chamber  57  for carrying out a development by causing the toner supplied from the developer container  52  to adhere to the photosensitive drum  20 . 
     The supply roller  58  and the developing roller  59  which acts as a developer carrier and makes contact with both the supply roller  58  and the photosensitive drum  20  and supplies the photosensitive drum  20  with the toner supplied from the supply roller  58 , are rotatably supported on the developing chamber  57 . An elastic, thin plate-like blade  64  arranges the toner, which has been supplied from the supply roller  58  and has adhered to the developing roller  59 , in a prescribed layer thickness. The toner supplied to the photosensitive drum  20  from the developing roller  59  constantly becomes a fixed amount. 
     An agitator  80 , which is an agitation member, is provided in the developer container  52 . Also, the heretofore described light transmission windows  56   a  and  56   b  are provided in the casing  51  end walls  51   a  and  51   b  forming sidewalls (wall surfaces extending along the plane of  FIG. 2 ) of the developer container  52 . A loading hole  81  for use in loading the developer container  52  with the toner is formed in one end wall  51   a.    
     Of the above components, the agitator  80  includes the rotary shaft  55 , both ends of which are rotatably supported on the casing  51  end walls  51   a  and  51   b , an agitating portion  53  which agitates the toner contained in the developer container  52 , and a cleaning portion  54  for cleaning the light transmission windows  56   a  and  56   b  formed in the casing end walls  51   a  and  51   b . 
     The agitation portion  53  includes mainly an agitation body  53   a  for agitating the toner and a sliding contact portion  53   b  for conveying the toner to the developing chamber  57 . Of them, the agitation body  53   a , being an L-section member projecting from the rotary shaft  55 , has a plurality of openings  53   c  formed in an agitation surface which agitates the toner. Also, the sliding contact portion  53   b , being a sheet-like member formed from a flexible material (for example, PET: polyethylene terephthalate), is attached to a leading end of the agitation body  53   a.    
     The cleaning portion  54  includes a wiper  54   b  for wiping off the toner adhering to the light transmission window  56  and a wiper support  54   b  for supporting the wiper  54   b . Of them, the wiper support  54   a , being a plate-like member formed projecting from the rotary shaft  55 , is formed in such a way as to be perpendicular to an attachment end of the L-shaped agitation body  53   a , which is attached to the rotary shaft, and parallel to the leading end of the agitation body  53   a , to which the sliding contact portion  53   b  is attached. Also, the wiper support  54   a  has an amount of projection from the rotary shaft  55  set in such a way that, when rotating the agitator  80 , a leading end portion of the wiper support  54   a  passes a position facing the light transmission window  56 . The wiper  54   b , being a member made of urethane rubber, is attached to the leading end portion of the wiper support  54   a  in such a way as to, when rotating the agitator  80 , make sliding contact with a portion in which the light transmission window  56  is formed. 
     The rotary shaft  55 , the agitation body  53   a  of the agitation portion  53 , and the wiper support  54   a  of the cleaning portion  54  are integrally molded from a synthetic resin which has a strength necessary for agitating the toner. 
     Both the ends of the rotary shaft  55  are formed in such a way as to pass through the casing end walls  51   a  and  51   b . A gear  63 , which is a drive member for transmitting a driving force to the rotary shaft  55 , is fixed to one end (hereafter referred to as a drive end) exposed to an outside of the casing end wall  51   a . Also, a detected portion  94 , which is for causing a detector portion  93  disposed in a laser printer  1  body to detect a rotary condition of the rotary shaft  55 , is provided at the other end (hereafter referred to as a driven end) of the rotary shaft  55  which is exposed to an outside of the casing end wall  51   b.    
     Also, rotary shafts of the supply roller  58  and the developing roller  59  are formed in such a way that one-end portions thereof pass through the casing end wall  51   a , and gears  67  and  66  (refer to  FIG. 5 ) are fixed respectively to ends of the supply roller  58  and the developing roller  59  which are exposed to the outside of the casing end wall  51   a.    
       FIG. 5  is an illustration schematically showing an outer surface of the casing end wall  51   a  (on the drive end side of the rotary shaft  55 ) of the developing cartridge  50 . 
     As shown in  FIG. 5 , a gear  65 , to which is applied a driving force from the laser printer  1  body, is provided on the outer surface of the casing end wall  51   a , and the gears  67  and  66  fixed to the rotary shafts of the supply roller  58  and the developing roller  59  are configured in such a way that the driving force is directly transmitted to both of them from the gear  65 . Also, the gear  63  fixed to the rotary shaft  55  of the agitator  80  is configured in such a way that the driving force from the gear  65  is transmitted in a decelerated condition via a change gear  68 . 
     Consequently, when a driving force rotating clockwise as seen in  FIG. 5  is applied to the gear  65 , the supply roller  58 , the developing roller  59  and the agitator  80  rotate in directions indicated by the arrows in  FIG. 1 . 
     Next, a description will be given of the detector portion  93  provided in the laser printer  1  and the detected portion  94  provided at the driven end of the rotary shaft  55 .  FIG. 4  is a perspective view showing a configuration of the detector portion  93  and the detected portion  94 . 
     The detector portion  93 , being formed as a squared U-section shape, is an optical sensor (herein, a photo sensor) formed by a light emitting portion (for example, a light emitting diode) and a light receiving portion  92  (for example, a phototransistor), and the light emitting portion  91  and the light receiving portion  92  are attached to opposite ends of the squared U-section shape. 
     An opening portion of the detector portion  93  is disposed facing a bottom of the laser printer  1  in such a way that the detected portion  94  does not interfere with the detector portion  93  when attaching the developing cartridge  50  to the laser printer  1  body (in the same way also as in the case of attaching the drum cartridge having attached thereto the developing cartridge). 
     Also, the detected portion  94 , being a member made of a circular thin plate, is fixed to the rotary shaft  55  in such a way as to be driven under a rotating force of the rotary shaft  55 . 
     The detected portion  94  is configured in such a way as to be sandwiched between the light emitting portion  91  and the light receiving portion  92  of the detector portion  93  when the developing cartridge  50  attached to the drum cartridge  5  is attached to the laser printer  1  body (the developing cartridge  50  (that is, the detected portion  94 ) is attached and detached in a direction of an arrow Y shown in  FIG. 4 ). 
     Furthermore, the detected portion  94  has a notch  95  provided in a position which is detected by the sensor, that is, a portion which corresponds to a path extending from the light emitting portion  91  toward the light receiving portion  92 . That is, a configuration is such that light emitted from the light emitting portion  91  of the sensor passes through the notch  95  and is detected in the light receiving portion  92  of the sensor. 
     That is, the light emitted from the light emitting portion  91  is turned ON when it passes through the notch  95  of the detected portion  94  and can be received by the light receiving portion  92 , while the light is turned OFF when it is blocked by the thin plate and cannot be received by the light receiving portion  92 . For this reason, for example, when a notch  95  such as the one shown in  FIG. 10A  is formed in the detected portion  94 , a pulse waveform such as the one shown in  FIG. 11A  can be obtained as a detection signal. 
       FIGS. 10A to 10C  are illustrations regarding shapes of the notch  95  in the detected portion  94 , and  FIGS. 11A to 11C  are illustrations of pulse waveforms obtained as a result of a detection of the detected portion  94  by the detector portion  93 . 
     Consequently, by changing the shape and number of notches  95  formed in the detected portion  94 , it is possible to obtain different patterns of pulse waveform. That is, in this aspect, the number of notches  95  is changed (to two) according to an initial amount of toner loaded in the developer container  52 . For example, by forming one notch  95  in the detected portion  94  as shown in  FIG. 10A , it is possible to produce the pulse waveform in  FIG. 11A  which can be obtained in a case in which a developing cartridge having a small initial loading amount of toner has been attached. By forming two notches  95   b  in the detected portion  94  as shown in  FIG. 10B , it is possible to produce the pulse waveform in  FIG. 11B  which can be obtained in a case in which a developing cartridge having a large initial loading amount of toner has been attached. Although the number of notches  95  is changed according to the initial loading amount of toner at this point, it is also acceptable to change the shape of the notch  95 . For example, by increasing the width of a notch  95   c  as shown in  FIG. 10C , it is possible to produce the pulse waveform in  FIG. 11C  which can be obtained in the case in which the developing cartridge having the large initial loading amount of toner has been attached. 
     As the detector portion  93  is disposed in the laser printer  1  body, it is necessary that the detected portion  94  be positioned outside the drum cartridge  5 . For this reason, a groove (a guide rail  85 ), which is used to prevent the developing cartridge  50  from interfering with the rotary shaft  55  when attaching and detaching the developing cartridge  50  and thus facilitate the attachment and detachment of the developing cartridge  50 , is formed in a portion of the drum cartridge  5  on the driven end side of the rotary shaft  55  provided with the detected portion  94 . 
     &lt;Description of Operation Control&gt; 
       FIG. 6  is a block diagram showing a configuration of a control system of the laser printer  1 . 
     As shown in  FIG. 6 , the control system of the laser printer  1  is configured around a controller  200  including a well-known microcomputer equipped with an ROM  213  storing various control programs, an RAM  212  storing information obtained from each section, a CPU  210  which executes a control over each section based on the programs stored in the ROM  213 , and an input/output interface (hereafter referred to as an I/O  211 ) in charge of providing communication between each section and the CPU  210   
     The CPU  200  is connected via the I/O  211  to sections, such as a detection section  215  acting as a circuit of the detector portion  93  which detects an operating condition of the detected portion  94 , a drive section  216  for transmitting the driving force to the gear  65  of the developing cartridge  50 , a printing section  217  for processing a series of printing operations ranging from an emitting of the laser beam to a printing on the sheet of paper, and a display section  218  for notifying a user of a variety of information. The sections are controlled by the controller  200 . 
     A printing process executed by the CPU  210  of the laser printer  1  will be described using a flowchart in  FIG. 7 . 
     When the printing process is started, first, in S 500 , it is determined whether or not the developing cartridge  50  has been replaced, and a setting change process is executed in which various settings are changed in accordance with an initial developer loading amount contained in a developing cartridge. 
     After the setting change process is carried out, in S 510 , a command to drive the gear  65  of the developing cartridge  50  is transmitted to the drive section  216 . Based on the command, the driving force is transmitted to the gears  63 ,  66  and  67  via the gear  65 , thereby rotating the agitator  80  (the rotary shaft  55 ), the supply roller  58  and the developing roller  59 . 
     Subsequently, in S 520 , a detection signal is obtained by causing the detection section  215  to detect a rotary condition of the rotary shaft  55 . In S 530 , by comparing a pulse waveform of the detection signal obtained in S 520  and a pulse waveform which, being obtained in a normal rotary condition, is stored in advance in the ROM  213 , it is determined whether or not there is an abnormality. As used herein, the abnormality refers to a case in which the rotation of the rotary shaft  55  is stopped and no pulse waveform can be obtained (that is, no detection signal can be obtained), a case in which a cycle of the pulse waveform significantly exceeds a prescribed range set in advance, and a like case. 
     Then, when there is the abnormality in the pulse waveform as a result of the determination in S 530 , as the rotary shaft  55  is broken in the vicinity of the drive end of the rotary shaft  55  which is provided with the gear  63  (the breaking, including a fracture of the rotary shaft, refers to a condition in which the rotary shaft cannot rotate normally), the driving force is not transmitted to the driven end side of the rotary shaft  55  which is provided with the detected portion  94 , so that it is determined that the detected portion  94  is not rotating normally. 
     In this case, in the next S 560 , in order to prompt the user to replace the developing cartridge  50  by notifying him/her that the abnormality has occurred in the rotary shaft  55  of the agitator  80 , an abnormality process is carried out for causing the display section  218  to display the occurrence of the abnormality. Furthermore, in the abnormality process, an operation of the drive section  216  is limited in such a way that the driving force is not transmitted from the laser printer  1  body to the developing cartridge  50 . 
     In the case of limiting the operation of the drive section  216 , it is acceptable to stop the operation of the printing section  217  after stopping the drive of the drive section  216  immediately after recognizing the breaking of the rotary shaft  55 , or it is also acceptable to stop the operation of the printing section  217  after stopping the drive of the drive section  216  after causing the printing section  217  to print a certain number of copies. 
     Also, if the detection result obtained in S 520  shows a normal pulse waveform as a result of the determination in S 530 , the process moves to S 540 , wherein the printing section  217  is caused to carry out a normal printing operation as a printing process. In the printing process, information on a use period of the developing cartridge  50  (that is, a period in which the developing cartridge  50  can be used without toner deterioration) is constantly updated (reduced) in accordance with the number of copies printed and the number of revolutions of the rotary shaft  55 . 
     Subsequently, in S 550 , a stop process is carried out in which the agitation portion  53  of the agitator  80  is stopped in a stop position which is preset in such a way as to prevent the agitation portion  53  from remaining under a pressure of the toner during the stopping of the drive. 
     After that, the printing process is finished. 
     Next, the stop process in S 550  in the printing process will be described using a flowchart shown in  FIG. 8 . 
     In the stop process, first, in S 600 , the detection section  215  is caused to detect the rotary condition of the rotary shaft  55 , thereby obtaining a detection signal. 
     Then, in S 610 , a timing, at which a rotation phase of the rotary shaft  55  falls in a preset reference phase, is extracted from the detection signal obtained in S 600 . 
     In the next S 620 , based on the timing extracted in S 610 , by transmitting a command to stop the drive of the gear  65  to the drive section  216  at the time a preset drive time has elapsed, the agitation portion  53  of the agitator  80  is stopped in a preset stop position (that is, the cleaning portion  54  also stops in a preset position). 
     After that, the process is returned to the printing process, and all the processes are finished. 
     The stop position refers to a position which prevents the agitation portion  53  and the cleaning portion  54  from remaining in contact with the toner during the stopping of the drive, and a position in which the agitation portion  53  and the cleaning portion  54  do not overlap the loading hole formed in the developing cartridge  50 . 
     That is, as a relationship between the rotation phase of the rotary shaft  55  corresponding to the stop position and the reference phase is known, a drive time necessary for causing the agitator  80  to stop in the stop position is easily calculated from a drive condition (a rotation speed and the like) of the rotary shaft  55 . Consequently, it is sufficient that, for example, a table, which has the drive condition (the rotation speed and the like) of the rotary shaft  55  related to the drive time calculated from the drive condition, is stored in advance in the ROM  213 , and that the drive time is set in accordance with the table and the drive condition of the rotary shaft  55  at that time. 
     Next, the setting change process of S 500  in the printing process will be described using a flowchart shown in  FIG. 9 . 
     First, when the setting change process is executed, in S 700 , it is determined whether or not a newly attached developing cartridge  50  is brand-new. This determination is carried out by a not-shown movable detection gear attached to the developing cartridge  50 . Specifically, when the brand-new developing cartridge  50  is attached to the laser printer  1 , the detection gear moves, and a detection lever operates along with the movement of the gear. The movement of the detection lever is detected by the sensor, thereby determining whether or not the developing cartridge  50  is brand-new. 
     As the detection as to whether or not the cartridge is brand-new is a publicly known art, a further description will be omitted (for example, refer to JP-A-2005-55544). 
     After that, if a result of the determination in S 700  is that the newly attached developing cartridge  50  is not brand-new (for example, if the developing cartridge detached before is attached again), the process returns to the printing process as it is, and then moves to S 510  in the printing process. 
     On the other hand, if a result of the determination in S 700  is that the newly attached developing cartridge  50  is brand-new, a command to drive the gear  65  of the developing cartridge  50  is transmitted to the drive section  216 . Based on the command, the driving force is transmitted to the gears  63 ,  67  and  66  via the gear  65 , thereby rotating the agitator  80  (the rotary shaft  55 ), the supply roller  58  and the developing roller  59 . 
     Then, the detection section  215  is caused to detect the rotary condition of the rotary shaft, thereby obtaining a detection signal. 
     In the next S 720 , by comparing a pulse waveform of the detection signal obtained in S 710  and a plurality of kinds of pulse waveform which has been stored in advance in the ROM  213  and prepared in accordance with the initial toner loading amount of the developing cartridge  50 , the type (that is, the initial toner loading amount) of the newly attached developing cartridge  50  is identified (refer to  FIGS. 11A ,  11 B and  11 C). 
     In the next S 730 , the information on the use period of the developing cartridge  50  (that is, the period of time for which the developing cartridge  50  can be used without toner deterioration), which has been stored in the ROM  213 , is initialized as contents corresponding to the developing cartridge  50  identified in S 720 . 
     After that, the process returns to the printing process and then moves to S 510 . 
     S 560  in the printing process corresponds to the abnormal stop means of the invention, S 620  in the stop process corresponds to the stop control means of the invention, S 700  in a cartridge replacement process corresponds to the use detection means of the invention, and S 730  corresponds to the use period setting means of the invention. 
     &lt;Advantageous Effects of this Aspect&gt; 
     As described heretofore, in the laser printer  1  (the developing cartridge  50 ) of this aspect, the detected portion  94  for causing the detector portion  93  to detect the rotary condition of the rotary shaft  55  (and thus the agitator  80 ) is provided not on the drive end side of the rotary shaft  55 , but on the driven end side of the rotary shaft  55 . 
     For this reason, in the event that the rotary shaft  55  is broken in the vicinity of a gear setting portion on the drive end side of the rotary shaft  55  (the breaking of the rotary shaft  55 , including a fracture of the rotary shaft, refers to the condition in which the rotary shaft cannot rotate normally), the rotary condition of the rotary shaft  55  which is detected by the detector portion  93  via the detected portion  94  becomes different from an expected operation of the detected portion  94 . 
     Consequently, according to the laser printer  1  of this aspect, it is possible to reliably detect the abnormality of the agitator  80  (the breaking of the rotary shaft  55 ) from a result of the detection in the detector portion  93 . 
     Also, in the event that the abnormality of the agitator  80  has been detected, as the drive of the developing cartridge  50  is stopped and an unnecessary printing process is not carried out, it is possible to suppress a defective printing. 
     Also, in the laser printer  1  of this aspect, the detection signal obtained from the detector portion  93  has a pulse waveform corresponding to the shape and number of notches  95  in the detected portion  94 , and a configuration is such that the timing at which the rotary shaft  55  falls in the reference phase can be specified based on a pulse generating timing, and such that the initial loading amount of toner can be specified from a pulse pattern. 
     Consequently, according to the laser printer  1  of this aspect, when the operation of the developing cartridge  50  is stopped, the agitator  80  can be stopped in an appropriate stop position in which the pressure from the toner is prevented from being applied to the agitation portion  53 , and furthermore which does not overlap the loading hole  81 . 
     As a result, as a deformation of the agitator  80  due to the pressure from the toner is prevented, as well as being able to lengthen a useful life of the agitator  80 , when a toner loading is required, it is possible to smoothly insert the loading nozzle into the loading hole  81  and easily load the developing cartridge  50  with the toner. 
     Also, according to the laser printer  1  (the developing cartridge  50 ) of this aspect, as a configuration is such that, in the event that the replacement of the developing cartridge  50  is detected, the use period of the developing cartridge  50  is set in accordance with the pulse waveform pattern of the detection signal obtained from the detector portion  93 , it is possible to prevent a printing with a deteriorated toner and, as a result, suppress a defective printing. 
     Also, in the laser printer  1  of this aspect, as the detector portion  93  is disposed in such a way as not to interfere with the detected portion  94 , it is possible to prevent a deterioration and a failure due to a contact and lengthen the useful life. Also, even when the developing cartridge  50  is attached and detached, as the detector portion  93  does not make contact with the detected portion  94 , the developing cartridge  50  can be easily attached and detached without wasting a user&#39;s time. 
     Also, according to the laser printer  1  of this aspect, as a photo sensor is employed as the detector portion  93 , even in the event that a magnetic toner is in use, it will not affect the detection result of the detector portion  93 , and it is possible to reliably detect the rotary condition of the rotary shaft  55 . 
     [Another Aspect] 
     Next, a description will be given of a second aspect. 
     Although a monochromatic laser printer has been described in the above-described one aspect, a color laser printer using a plurality of colors will be described in this aspect. 
     As shown in  FIG. 12 , a color laser printer  100  (hereafter referred to as a printer body) of this aspect is a well-known one equipped with four kinds of developing cartridge  110 , a developing cartridge  110 K loaded with a toner whose color is black, a developing cartridge  110 C loaded with a toner whose color is cyan, a developing cartridge  110 M loaded with a toner whose color is magenta, and a developing cartridge  110 Y loaded with a toner whose color is yellow. 
     That is, the printer body  100  is formed with four attaching portions to each of which a developing cartridge  110  is detachably attached, and quite the same detector portion (sensor) as that of the above one aspect is disposed in each of the attaching portions. Also, attachment positions of the developing cartridges  110 K,  110 C,  110 M and  110 Y are predetermined. 
     Also, the developing cartridges  110 K,  110 C,  110 M and  110 Y are configured in the same way as the developing cartridge  50  of the above one aspect, apart from detected portions. 
     That is, the shape and number of notches formed in each of the detector portions are set in such a way that the developing cartridges  110 K,  110 C,  110 M and  110 Y can obtain pulse waveforms shown in  FIGS. 14A ,  14 B,  14 C and  14 D from the detector portions, respectively. 
     Also, as the printer body  100  is also arranged in the same way as the laser printer  1  of the above one aspect except that a plurality of components corresponding to the developing cartridge  110  exists, a description will be omitted herein. The same components as those of the above one aspect will be described using identical reference numerals. 
     At this point, an attachment position determination process executed by the controller  200  of the printer body  100  will be described in accordance with a flowchart shown in  FIG. 13 . 
     When the attachment position determination process is started, first, in S 810 , a command to drive the gear  65  of the developing cartridge  50  is transmitted to the drive section  216 . Based on the command, the driving force is transmitted to the gears  63 ,  66  and  67  via the gear  65 , thereby rotating the agitator  80  (the rotary shaft  55 ), the supply roller  58  and the developing roller  59 . 
     Subsequently, in S 820 , the detection section  215  is caused to detect the rotary condition of the rotary shaft  55 , thereby obtaining a detection signal. 
     In S 830 , it is determined whether or not a pulse waveform of the detection signal obtained in S 820  conforms to a pulse waveform which is preset for a cartridge attaching portion to which the relevant developing cartridge is attached. That is, in S 830 , it is determined whether or not a toner color of a developing cartridge  110  attached to a cartridge attaching portion conforms to a toner color which is specified in advance for the cartridge attaching portion. 
     As a result of the determination in S 830 , if a toner color of a developing cartridge  110  attached to a cartridge attaching portion does not conform to a toner color which is specified in advance for such a cartridge attachment portion, the process moves to S 860 . 
     In S 860 , in order to prompt the user to attach an appropriate developing cartridge  110  again, an attachment correction process is carried out in which the display section  218  is caused to display the fact that the developing cartridge attached to the cartridge attaching portion is wrong. After that, the process moves to S 850 . 
     However, if, in S 830 , a toner color of a developing cartridge  110  attached to a cartridge attaching portion conforms to a toner color which is specified in advance for such a cartridge attachment portion, a printing process is carried out in S 840 . 
     Then, after a stop process is carried out in the next S 850 , this process is finished. 
     The printing process in S 840  is the same as the heretofore described printing process in S 540 , and the stop process in S 850  is the same as the stop process in S 550  (S 600  to S 620 ). 
     With the thus configured developing cartridge  110  and printer body  100 , a wrong color developing cartridge  110  can be prevented from being attached. As a result, it is possible to suppress an occurrence of a defective printing. 
     [Other Aspects] 
     Although the aspects of the invention have been described so far, the invention is not limited to the aspects, but can be practiced in various modes without departing from the scope of the invention. 
     In the aspects, the detected portion  94  is formed from a circular thin plate but, without being limited thereto, may be a detected portion  96  such as the one shown in  FIG. 15 . 
     In this case, the detected portion  96  includes a portion to be fixed to the rotary shaft and a cylindrical portion which, projecting from an edge of the circular thin plate, is detected by a detector portion  98 . The detector portion  98  has the same configuration as the detector portion  93  of the above one aspect. Then, the cylindrical portion is formed with a notch  97  for causing the detector portion  98  to detect the rotary condition of the rotary shaft. 
     In a case of employing such a detected portion  96 , in order to prevent the detected portion  96  from interfering with the detector portion  98  during the attachment and detachment of the developing cartridge (the developing cartridge (that is, the detected portion  96 ) is attached and detached in a direction of the arrow Y shown in  FIG. 15 ), the detector portion  98  is preferably of a movable structure in such away that it can retract from and return to a normal position crossing a movement path of the detected portion  96 . 
     Also, although the detected portion  94  is formed with the notch  95  for obtaining a pulse waveform, a hole formed passing through the detected portion  94  is also acceptable. It is also acceptable that a light emitting portion  91  and a light receiving portion  92  of the detector portion  98  are disposed on the same surface side of the detected portion  94 , and that a strip of a member which reflects light like a mirror is fixed to the detected portion  94 . That is, any structure is acceptable so long as it can detect a pulse waveform of a constant frequency from the rotary condition of the rotary shaft  55 . 
     Also, although, in the aspects, a photo sensor is employed as the detector portion  93 , it is also acceptable to detect the rotary condition of the rotary shaft using a magnetic sensor. 
     Although, in the aspects, the agitator  80  and the detected portion  94  are structured in such a way that they are formed as separate members and integrally fixed afterward, it is also acceptable that they are integrally molded in advance.