Patent Publication Number: US-6336012-B1

Title: Developing device, process cartridge and electric energy supply part to developing roller

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a developing device for an image forming apparatus, a process cartridge and an electric energy supply part therefor. 
     Here, the image forming apparatus forms an image on a recording material through an electrophotographic process for example. Examples of the electrophotographic apparatus include an electrophotographic copying machine, electrophotographic printer (for example a laser beam printer, LEDprinter or the like), facsimile machine, word processor and the like. 
     The process cartridge contains an image bearing member and at least one charging means, developing means and cleaning means, which are unified into a cartridge which is detachably mountable to an image forming apparatus. 
     In the field of an electrophotographic image forming apparatus using an electrophotographic image forming process, a process cartridge type is used in which an electrophotographic photosensitive drum and process means actable on the electrophotographic photosensitive drum are unified into cartridge which is detachably mountable to a main assembly of an electrophotographic image forming apparatus. With this process cartridge type, the maintenance operation for the electrophotographic image forming apparatus can be carried out in effect by the users, so that operativity is remarkably improved. Therefore, the process cartridge type is widely used in the field of image forming apparatus. 
     In the process cartridge, an electrostatic latent image formed on the electrophotographic photosensitive member is developed by developing means which develops the electrostatic latent image formed on the electrophotographic photosensitive member with the toner (developer) by a developing roller which is a developer carrying member. More particularly, a developing bias is applied to the developing roller to transfer the toner onto the electrophotographic photosensitive member from the developing roller in accordance with the electrostatic latent image so that visualized toner image is provided. 
     As for the method for applying a developing bias the developing roller, as shown in FIG. 10, a flange member F of an electroconductive material is provided at the end of the developing roller D, and an electrode in the form of a compression coil spring Sp is mounted to the flange member F for electrical conduction. When the developing device is mounting to the main assembly of the operators, the contact member C is electrically connected to an electric energy supply member V provided in the main assembly of the apparatus. 
     As for another method of applying a developing bias the developing roller, as shown in FIG. 11 an elastic contact portion Cs is provided in the contact member C, and the elastic contact portion Cs is contacted to flange member F of electroconductive material at an end of the developing roller D. When the developing device is mounted to the main assembly of the apparatus, the contact member C is electrically connected to the electric energy supply member V provided in the main assembly of the apparatus. 
     In such a case, the compression coil spring Sp or the flange member F is rotated integrally with the developing roller D so that it is in sliding relation with the contact member C, and therefore, generally, electroconductive grease is applied the sliding portion Cp. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a principal object of the present invention to provide a developing device and an assembling method in which a contact portion for applying a developing bias to a developer carrying member is improved in reliability. 
     It is another object of the present invention to provide a process cartridge and an assembling method in which a contact portion for applying a developing bias to a developer carrying member. It is a further object of the present invention to provide an electric energy supply part in which an electric energy supply part for electric energy supply of developing bias to a developer carrying member has a magnet with which the positional accuracy in the developer carrying member is improved. 
     It is a yet further object of the present invention to provide an electric energy supply part for electric energy supply of developing bias away developer carrying member with which an electrical connection with an electroconductive portion on a magnet disposed inside said developer carrying member. 
     These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration of a contact structure of a developing roller according to an embodiment of the present invention. 
     FIG. 2 is perspective views of a magnet and a fixed contact and a cylindrical electrode assembled with a magnet. 
     FIG. 3 is perspective views of a magnet, a fixed contact and cylindrical electrode assembled therewith. 
     FIG. 4 is a perspective view of a contact support and a sliding contact. 
     FIG. 5 is a perspective view of the developing roller which is being mounted to the contact support and the sliding contact. 
     FIG. 6 is a perspective view in which the developing roller assembled with the contact support and the sliding contact and the cylindrical electrode and the fixed contact which are being assembled with the developing roller. 
     FIG. 7 is a schematic view of an electrophotographic image forming apparatus which is loaded with a process cartridge. 
     FIG. 8 is an illustration of a structure of a process cartridge. 
     FIG. 9 is an illustration of a mounting structure of a process cartridge. 
     FIG. 10 is a schematic illustration of a contact structure of a developing roller. 
     FIG. 11 is a schematic illustration of a contact structure of a developing roller. 
     FIG. 12 is an illustration of a cylindrical electrode according to a modified example. 
     FIG. 13 is a perspective view of the cylindrical electrode and fixed contact shown in FIG. 12 assembled with the magnet 
     FIG. 14 is a schematic illustration of engaging relation meeting a projection of the cylindrical electrode and a recess of a left-hand shaft portion of the magnet. 
     FIG. 15 is a schematic illustration of an erroneous angle between the cylindrical electrode and the left-hand shaft portion of the magnet. 
     FIG. 16 is a schematic illustration of an engaging relation between a projection of a cylindrical electrode and a recess of a left-hand shaft portion of a magnet according to a modified example. 
     FIG. 17 is a perspective view of a fixed contact. 
     FIG. 18 is a front view of a sliding contact. 
     FIG. 19 is a side view of a sliding contact. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A description will be made as to the embodiment according to the present invention in conjunction with the accompanying drawings. 
     Referring to FIGS. 1 to  9 , there are shown a developing device, a process cartridge having the developing device and an electrophotographic image forming apparatus to which the process cartridge is mountable. 
     First, referring to FIGS. 7 to  9 , a description will be made as to the general arrangement of the electrophotographic image forming apparatus, and then, referring to FIGS. 1 to  6 , a description will be made as to the contact structure for a developing roller. Then, referring to FIGS. 14 to  16 , a description will be made as to a structure for preventing erroneous assembling. 
     (General Arrangement) 
     In the electrophotographic image forming apparatus (laser beam printer) A, as shown in FIG. 7, information light modulated in accordance with image information supplied from an optical system  1  is projected onto an electrophotographic photosensitive member in the form of a drum (photosensitive drum)  7  to form an electrostatic latent image thereon, and the sealing is developed withdeveloper into a toner image. In synchronism with the formation of toner image, a recording material  2  separately recording paper or an OHP sheet is supplied one by one from a cassette  3   a  by pick-up roller  3   b  and a press-contact member  3   c  press-contacted thereto and is fed by feeding means  3  including a pair of feeding rollers  3   d  and a pair of registration rollers or the like; and the toner image formed on the photosensitive member in the process cartridge B is transferred onto the recording material  2  by application of a voltage to the transfer roller  4  (transferring means), and the recording material  2  is fed to fixing means  5  by a conveyer belt  3   f . The fixing means  5  includes a driving roller  5   a  and a fixing rotatable member  5   d  including a supporting member  5   c  and a cylindrical sheet rotatably supported on the supporting member  5   c , by which heat and pressure are applied to the recording material  2  which is passing through the fixing means, by which the transferred toner image is fixed on the recording material  2 . The recording material  2  is fed by a pair of discharging rollers and is discharged to a discharging portion  6  through a reverse feeding path. The image forming apparatus A is capable of receiving a sheet manually fed by manual insertion tray  3   i  and a roller  3   j.    
     (Process Cartridge) 
     On the other hand, the process cartridge B contains an image bearing member in the form of an electrophotographic photosensitive member and at least one process means. The process means include charging means for charging the electrophotographic photosensitive member, developing means for developing a latent image formed on the electrophotographic photosensitive member, a cleaning means for removing toner remaining on the surface of the electrophotographic photosensitive member. 
     As shown in FIG. 8, with the process cartridge B of this embodiment, the electrophotographic photosensitive member having a photosensitive layer (a photosensitive drum  7 ) is rotated, and the surface of the photosensitive drum  7  is uniformly charged by charging means in the form of a charging roller  8  supplied with a voltage, and then, the charged photosensitive drum  7  is exposed to a light image from the optical system  1  through an opening  9  to form an electrostatic latent image. The latent image is developed by developing means  10  (developing device). 
     The developing means  10  is fed the toner out of the toner accommodating portion  10   a  by rotatably first feeding member  10   b   1  and first second feeding member  10   b   2 . The developing roller  10   d  (developer carrying member) containing therein a fixed magnet (magnet)  10   c  is rotated, and a toner layer of toner particles triboelectrically charged by the developing blade  10   e  is formed on the surface of the developing roller  10   d , and a developing bias is applied to transfer the toner to the photosensitive drum  7  in accordance with the latent image so that visualized toner image is formed. 
     A transfer roller  4  is supplied with a voltage having a polarity opposite from that of the toner image to transfer the toner image onto the recording material  2 . Thereafter, the residual toner remaining on the photosensitive drum  7  is removed or scraped off by the cleaning blade  11   a , and is received by the receptor sheet  11   b , thus the residual toner is collected by the cleaning means. 
     The process cartridge B of this embodiment comprises a developing device frame  12   a  having a toner accommodating portion  10   a , a development lower frame  12   b , and a toner developing device frame  12  having a cap member  12   c  integrally welded therewith which contains the developing roller  10   d , the developing blade  10   e  and the like. The toner developing device frame  12  is coupled with a cleaning frame  13  accommodating the photosensitive drum  7 , the charging roller  8 , the cleaning means  11  and the like to constitute the cartridge which is detachably mountable to a cartridge mounting means provided in the main assembly  14  of the image forming apparatus. 
     As shown in FIG. 7, when the process cartridge B is mounted or demounted, an opening and closing member  15  is open by rotation about a shaft  15   a , and when the opening and closing member  15  is opened, there is a cartridge mounting space in the main assembly  14  of the apparatus. A frame  16  provided at each of left and right sides of the mounting space is provided with a cartridge mounting guide member  17  as shown in FIG. 9 in which only one of the guide members  17  are shown. On the other hand, a boss  18  (FIG. 8) is provided protected at the longitudinally outsides of the process cartridge B, and the process cartridge B is inserted so that bosses  18  are engaged with the guide grooves  19  formed by the guide member  17  and the frame  16 . In the rear portion of the groove  19 , a recess  19   a  is formed, and a shaft portion  18   a  of the boss  18  is inserted into the recess  19   a  by which the process cartridge B is mounted. At this time, the drum gear (not shown) mounted to the longitudinal end of the photosensitive drum  7  is engaged with a driving gear provided in the main assembly  14  of the apparatus to commit drive transmission to the photosensitive drum  7 . 
     (Contact Structure of Developing Roller) 
     Referring to FIG. 1 to FIG. 6, a description will be made as to a contact structure for applying a developing bias to the developing roller  10   d.    
     As shown in FIG. 1, the developing roller (first cylindrical portion)  10   d  comprises a non-magnetic electroconductive cylindrical member of aluminum, stainless steel or the like and a flange member (second cylindrical portion)  20   a ,  20   b  at each of the opposite ends. The flange member has an outer diameter which is smaller than that of the first cylindrical portion. The righthand side flange member  20   a  is fixed to a right-hand end  10   d R of the developing roller  10   d  by press-fitting, bonding, crimping or the like, and has a shaft portion  20   a   1  projected outwardly from a right-hand end  10   d R in a longitudinal direction of the developing roller  10   d . The outer periphery of the shaft portion  20   a   1  is rotatably supported by a bearing  21   a  fixed to the toner developing device frame  12  and the holder  24   a . On the other hand, a flange member  20   b  of metal such as aluminum, stainless steel or the like is fixed to the left-hand end  10   d L of the developing roller  10   d  by a press-fitting, crimping or another mechanical method, and comprises a shaft portion  20   b   1  functioning as a flange projected outwardly from the left-hand end  10   d L in the longitudinal direction of the developing roller  10   d . The outer periphery of the shaft portion  20   b   1  functioning as the flange is rotatably supported by a bearing  21   b  fixed to a toner developing device frame  12  and a holder  24   b . To the shaft portion  20   b   1 , a roller gear  22  is fixed by means of a key, a set screw or the like. With this structure, the driving force is transmitted from a drum gear (unshown) of a photosensitive drum  7  to the roller gear  22 , so that developing roller  10   d  is rotated at a predetermined rotational speed. In this embodiment, the flange (shaft portion  20   b   1 ) is made of metal such as aluminum, stainless steel or the like. Therefore, the support rigidity for the developing roller  10   d  is improved. Thus, the rotational accuracy of the rotation is improved. 
     In this embodiment, the shaft portion  20   b   1  and the first electroconductive portion which will be described hereinafter are out of contact from each other. For this reason, no developing bias is supplied from the shaft portion  20   b   1  to the developing roller  10   d.    
     A magnet  10   c  having a plurality of magnetic poles is contained in the developing roller  10   d . The magnet  10   c  has shaft portions  10   c   1  at left and right ends. The left and right shaft portions  10   c   1  are penetrated through center holes  20   a   2 ,  20   b   2  of the flange members  20   a ,  20   b  and are fixed into the supporting holes  24   a   1 ,  24   b   1  of the holders  24   a ,  24   b  fixed to the toner developing device frame  12 . 
     (First Electroconductive Portion (Cylindrical Electrode and Fixed Contact)) 
     As shown in FIGS. 2 and 3, a cylindrical electrode  28  and a fixed contact  29  having an electroconductivity is mounted to a shaft portion (left-hand shaft portion)  10   c   1  as one end shaft at one end (left side of the magnet  10   c ). The cylindrical electrode  28  and the fixed contact  29  constitute the first electroconductive portion. 
     The cylindrical electrode  28  is provided that left-hand shaft portion  10   c   1  of the magnet  10   c  and is extended in the longitudinal direction of the toner developing device frame  12  (the axial direction of the photosensitive drum  7 ). The cylindrical electrode  28  includes a cylindrical portion  28   e  in the form of a cylinder extending in the axial direction of the developing roller  10   d  at the center thereof, and is provided with projections  28   a ,  28   b  in the form of projected portions extending in the axial direction of the developing roller  10   d  at the left and right ends of the cylindrical portion  28   e , respectively. The cylindrical portion  28   e  is provided with a slit  28   c  formed in the axial direction of the developing roller  10   d . The inner diameter of the cylindrical portion  28   e  is slightly smaller than the outer diameter of the left-hand shaft portion  10   c   1  of the magnet  10   c . Therefore, when the cylindrical portion  28   e  is engaged with the left-hand shaft portion  101   c   1  of the magnet  10   c , the cylindrical portion  28   e  is expanded in the radial direction to slightly expand the slit  28   c , and the cylindrical electrode  28  is fixed to the left-hand shaft portion  10   c   1  by the restoring force of the cylindrical portion  28   e  of the left-hand shaft portion  10   c   1 . 
     At the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c , there is provided a projection  10   c   2  projected in the radial election of the left-hand shaft portion  10   c   1  and extending toward the free end at each of several positions spaced circumstantially (three positions in this embodiment), and the end portion is provided with a D-cut  10   c   3  for positioning the magnetic pole of the magnet  10   c  in the rotational direction (angle). The cylindrical electrode  28  is fitted (telescoped) around the left-hand shaft portion  10   c   1  so that the projections  28   a  provided at the right-hand end of the cylindrical portion  28   e  are engaged with the recess  10   c   22  between adjacent projections  10   c   2  at the base portion of the left-hand shaft portion  10   c   1 , respectively, by which the rotation of the cylindrical portion  28   e  relative to the left-hand shaft portion  10   c   1  is prevented. The telescopic motion of the cylindrical electrode  28  relative to the left-hand shaft portion  10   c   1  is stopped when the left-hand end end surface  28   d  of the cylindrical portion  28   e  reaches the bottom surface  10   c   4  of the D-cut  10   c   3  of the left-hand shaft portion  10   c   1 . Here, the left-hand end side projection  28   b  projected from the end surface  28   d  of the cylindrical portion  28   e  is such that it covers the left-hand shaft portion  10   c   1  at the arcuate portion  10   c   31  of the D-cut  10   c   3  of the left-hand shaft portion  10   c   1 , on the accurate surface. The outer diameter (a diameter of the circumscribed circle) of the projection  10   c   2  provided at a base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c  is larger than the outer diameter (a diameter of the circumscribed circle) of the projection  28   a  provided at the right-hand end side of the cylindrical portion  28   e  of the cylindrical electrode  28 , and is smaller than a rotational track of the rotational track of the sliding contact portion along which to the sliding arm  30   c  of the sliding contact  30  which will be described hereinafter slides of the fixed contact  29 . 
     After the cylindrical electrode  28  is fixed to the left-hand shaft portion  10   c   1  of the magnet  10   c  in this manner, the fixed contact  29  is telescoped from the free and of the left-hand shaft portion  10   c   1  to the base portion. 
     The fixed contrast  29  is electroconductive, and is electrically connected to the cylindrical electrode  28  to supply a developing bias coatings to the developing roller  10   d  through the sliding contact  30 , thus functioning as an electric energy supply member. As shown in FIGS. 2 and 17, the fixed contact  29  comprises a circular disk portion  29   a  functioning as a base provided with a through hole  29   c  (circular hole) from which the left-hand shaft portion  10   c   1  is penetrated, and a positive claw portions  29   b  functioning as a contact portion extended inwardly from the disk portion  29   a  and bent toward downstream with respect to the telescoping direction to the left-hand shaft portion  10   c   1 . The claw portion  29   b  is provided at each of three positions around the through hole  29   c . The inscribed circle diameter of the free ends of the claw portions  29   b  is smaller than the outer diameter of the cylindrical portion  28   e  of the cylindrical electrode  28  described in the foregoing. When the fixed contact  29  is telescoped to the left-hand shaft portion  10   c   1  from the free end side (FIG.  2 ), the claw portion  29   b  deformed by the difference between the outer diameter of the cylindrical portion  28   e  of the cylindrical electrode  28  and the inscribed circle diameter at the free ends of the claw portions  29   b  to produce contact pressure and fixing force between the cylindrical electrodes  28  and the fixed contact  29 . Thus, the fixed contact  29  is elastically contacted to and engaged to the cylindrical portion  28   e  of the cylindrical electrode  28  by the claw portions  29   b . By the engagement of the claw portions  29   b , the movement of the cylindrical portion  29   a  relative to the left-hand shaft portion  10   c   1  is limited in the circumferential direction. When the fixed contact  29  is further moved to the base portion of the left-hand shaft portion  10   c   1 , the fixed contact  29  is set such that claw portions  29   b  are received by the recesses  10   c   22  between the adjacent projection  10   c   2  provided at the base portion of the above-described left-hand shaft portion  10   c   1 . By doing so, the claw portions  29   b  are contacted to the projection  28   a  at the right-hand end side of the cylindrical electrode  28 , and the disk portion  29   a  is closely contacted to the shaft base portion  10   c   5  of the left-hand shaft portion  10   c   1 . Here, the radius of the circumscribed circle of the projections  10   c   2  at the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c  is larger than the radius of the inscribed circle of the bent base portions of the claw portions  29   a  of the fixed contact  29 . The height of the projections  10   c   2  measured in the axial direction is higher than the free end of the claw portion  29   a  of the fixed contact  29  when the fixed contact  29  is closely contacted to the shaft base portion  10   c   5 , by which the contact portion (projection  28   a  and claw portion  29   b ) between the cylindrical electrode  28  and the fixed contact  29  are protected. 
     (The Second Electroconductive Portion (Sliding Contact) 
     As shown in FIGS. 4 and 5, a sliding contact  30  (second electroconductive portion) is fixed to the contact support  31 , and they are inserted into the developing roller  10   d  (FIG.  1 ). 
     The contact support  31  comprises a cylindrical portion  31   a , a flange  31   b , a center through hole  31   c  formed in the flange  31   b , and a dowel  31   e  at an end surface  31   d  of the flange  31   b . The contact support  31  is electrically insulative and is produced from resin material by an injection molding process. 
     The sliding contact  30  is electroconductive, and is used as an electric energy supply part for supplying the developing bias to the developing roller  10   d  from the main assembly  14  of the apparatus. As shown in FIGS. 4,  18  and  19 , the sliding contact  30  comprises a disk portion  30   a  as a base closely contacted to the flange  31   b  of the contact support  31 , a plurality of (two in this embodiment) claw portions (first contact portion)  30   b  extended in the radial direction of the disk portion  30   a  and that downstream with respect to the inserting direction into the developing roller  10   d , and two sliding arms (second contact portion)  30   c  extend along a spiral line (unshown) about a line perpendicular to the surface  30   a   1  of the disk portion  30   a  and extending through the center thereof. The base in the form of the disk portion  30   a  is provided at the center with a through hole  30   d  having substantially the same diameter as the through hole  31   c  of the contact support  31 , and the disk portion  30   a  is provided with a mounting hole  30   e  for mounting the contact support  31  engageable with the dowel  3 l e  of the contact support  31 . 
     The contact support  31  and the sliding contact  30  are made integral with each other in the following manner. The dowel  31   e  of the contact support  31  is engaged with the mounting hole  30   e  of the sliding contact  30 , and the dowel  31   e  is deformed by heat, ultrasonic wave or the like (FIG.  5 ), by which the sliding contact  30  is fixed to the contact support  31 . Here, the mounting hole  30   e  of the sliding contact  30  and the dowel  3 l e  of the contact support  31  are formed such that center of the sliding contact  30  and the center of the contact support  31  are aligned correctly. 
     The combined structure of the contact support  31  and the sliding contact  30  is inserted into the developing roller  10   d  as shown in FIG.  5 . More particularly, the combined structure having the driving side flange member  20   b  at the left-hand end of the developing roller  10   d , is inserted into the developing roller  10   d  from the right-hand end  10   d R side which is open, with the contact support  31  side being at the leading end. Then, the combined structure is inserted into the developing roller  10   d  from the end  10   d R side with the contact support  31  side at the leading side, the cylindrical portion  31   a  of the contact support  31  is engaged with the hole portion  20   b   2  formed coaxially with the shaft portion  20   b   1  in the flange member  20   b . By doing so, the sliding contact  30  can be disposed coaxially with the developing roller  10   d . The insertion of the connected article into the developing roller  10   d  stops by the flange  31   b  of the contact support  31  abutting to the inner end surface  20   b   3  before the inner hole portion  20   b   2  of the flange member  20   b . The sliding contact  30  having been inserted into the developing roller  10   d  is contacted to the inner wall surface (inner surface)  10   d   1  of the developing roller  10   d  with a contact pressure which is provided by deformation of the claw portions  30   b . Here, the claw portions  30   b  are extended in the radial direction of the disk portion  30   a  and is bent upstream with respect to the inserting direction into the developing roller  10   d , and are easily flexed during the insertion, and simultaneously, when the force is applied in the pulling- out direction, the ends of the claw portions bite into the inner wall surface  10   d   1 . Therefore, the claw portions  30   b  function as a retention member for the sliding contact  30  relative to the developing roller  10   d.    
     (Connection of the Developing Roller with the Magnet) 
     As described in the foregoing, the developing roller  10   d  is a single part which contains the sliding contact  30  therein and electrically conducted with the sliding contact  30 . The magnet  10   c  is a single part containing the cylindrical electrode  28  at the left-hand shaft portion  10   c   1  and the fixed contact  29  fixed to the shaft base portion  10   c   5  at the left-hand shaft portion  10   c   1 . The two single parts are connected with each other in the following manner. 
     As shown in FIG. 6, the magnet  10   c  is inserted into the developing roller  10   d  at the right-hand end  10   d R side which is open with the left-hand shaft portion  10   c   1  having the cylindrical electrode  28  at the leading side. Then, the sliding arm  30   c  of the sliding contact  30  is contacted to the disk surface  29   a   1  of the disk portion  29   a  of the fixed contact  29  (FIG.  3 ). With the further insertion of the magnet  10   c , the sliding arm  30   c  of the sliding contact  30  is elastically deformed to provide reaction force, but the end surface  10   c   21  of the projection  10   c   2  of the magnet  10   c  (FIG. 3) is contacted to the surface  30   a   1  (FIG. 5) of the disk portion  30   a  of the disk portion  30   a  to indicate the impossibility of further insertion of the magnet  10   c . The flange member  20   a  is mounted to the right-hand end  10   d R of the developing roller  10   d  which is open by press-fitting, crimping, heat crimp or the like, by which the developing roller unit DU as shown in FIG. 1 is manufactured. As described in the foregoing, in the developing roller unit DU, the flange member  20   a ,  20   b  are rotatably supported by the bearings  21   a ,  21   b  supported by the toner developing device frame  12  and the holders  24   a ,  24   b , and are fixed by engagement of the shaft portions  10   c   1  at the opposite ends of the magnet  10   c  with the supporting holes  24   a   1 ,  24   b   1  of the holders  24   a ,  24   b . Here, the shaft portion  20   b   1  of the flange member  20   b  covers the cylindrical portion  28   e  leaving the left side projection  28   b  of the cylindrical electrode  28  mounted to the left-hand shaft portion  24   b   1  is D-cut in the shape for angle determination of the magnet  10   c.    
     (Third Electroconductive Portion (Fixed Electrode Member)) 
     As shown in FIG. 1, a fixed electrode member  25  as a third electroconductive portion is fixed to the holder  24   b  of the toner developing device frame  12 . The holder  24   b  supports the D-cut  10   c   3  at the free end of the left-hand shaft portion  10   c   1  of the magnet  10   c  with which the cylindrical electrode  28  of the developing roller unit DU is engaged by the supporting hole  24   b   1  from the D-cut described above. The fixed electrode member  25  is provided with a contact portion (first electrical contact portion)  25   b  which enters the cut-away portion  24   b   2  which is continued with the supporting hole  24   b   1  in the above-described holder  24   b  at the position adjacent one longitudinal end of the developing roller  10   d  and which is contacted to the projection  28   b  at the left-hand end side of the cylindrical electrode  28 . It further comprises an exposed portion (second electrical contact portion)  25   a  which is exposed outwardly for electric connection with the apparatus side contact  26  which is electrically connected with the voltage source of the main assembly  14  of the apparatus. 
     The contact portion  25   b  and the exposed portion  25   a  are integrally formed. 
     The contact portion  25   b  functioning as the first electrical contact portion is contacted to the left-hand end side projection  28   b  of the cylindrical electrode  28  to elastically deform, and is contacted to the projection  28   b  with the force provided by the elastic deformation (elastic force). The projection  28   b  at the left-hand end of the cylindrical electrode  28  is designed such that it is disposed on the arcuate surface of the arcuate portion  10   c   31  of the D-cut  10   c   3  provided at the free end of the left-hand shaft portion  10   c   1  to fix the angular position of the magnet  10   c  as described hereinbefore. 
     More particularly, the projection  28   b  of the cylindrical electrode  28  at the left-hand end side receives a reaction force in the radial direction of the left-hand shaft portion  10   c  from the contact portion  25   b  of the contact portion  25   b , by which it is urged onto the arcuate surface of the arcuate portion  10   c   31  of the D-cut  10   c   3 . By this, the D-cut  10   c   3  of the left-hand shaft portion  10   c   1  is urged toward the flat portion (flat surface portion)  10   c   32  away from the arcuate portion  10   c   31  by the projection  28   b  of the cylindrical electrode  28  through the contact portion  25   b  of the fixed electrode member  25 . By doing so, the angle deviation of the magnet  10   c  due to the play between the supporting hole  24   b   1  of the holder  24   b  and the D-cut  10   c   3  of the left-hand shaft portion  10   c   1  of the magnet  10   c , can be prevented so that supporting accuracy can be improved in the radial direction of the magnet  10   c.    
     The sliding arm  30   c  of the sliding contact  30 , as described in the foregoing, is shaped into a spiral having an axis of a line perpendicular to the disk portion  30   a  through the center thereof as described in the foregoing, and therefore, the contact pressure provided by contact of the fixed contact  29  to the disk portion  29   a  is in the axial direction of the developing roller  10   d  and the magnet  10   c . By doing so, the developing roller  10   d  and the magnet  10   c  are movable in the direction away from each other. Therefore, the developing roller  10   d  and the magnet  10   c  move by the amount responded to the play in the axial direction until the axial end is contacted to the bearings  21   a ,  21   b  and/or holders  24   a ,  24   b . More particularly the sliding arm  30   c  of the sliding contact  30  functions as an urging means for urging the developing roller  10   d  and the magnet  10   c  in the opposite direction along the axis, by which the positional accuracy of the magnet  10   c  in the axial direction is improved. Thus, the positional accuracy of the magnet  10   c  is improved in the axial direction by the sliding arm  30   c  of the sliding contact  30 , simultaneously with the improvement of the supporting accuracy in the radial direction of the magnet  10   c  by the contact portion  25   b  of the fixed electrode member  25  described above. As a result, in the developing process of the electrophotographic image forming process, the developing property of the electrostatic latent image is improved when the toner image is formed by applying the developing bias to the developing roller  10   d  to transfer the toner from the surface of the developing roller  10   d  to the photosensitive drum  7  in accordance with the electrostatic latent image formed thereon. 
     The exposed portion  25   a  as the second electrical contact portion is disposed at a position for contact with the apparatus side contact  26  which is the main assembly side electrical contact connected with the voltage source  27  of the main assembly  14  when the process cartridge B containing the developing roller unit DU is mounted to the main assembly  14  of the apparatus. By doing so, when the process cartridge B is loaded into the main assembly  14  of the apparatus, the exposed portion  25   a  of the fixed electrode member  25  which is exposed to the outside of the holder  24   b  of the toner developing device frame  12 , is contacted to the contact  26  connected to the voltage source  27  of the main assembly  14  of the apparatus. 
     By this, the developing roller  10   d  and the voltage source  27  of the main assembly  14  of the apparatus are electrically connected with each other by way of (1) the contact between the apparatus side contact  26  and the exposed portion  25   a  of the fixed electrode member  25 , (2) the contact between the contact portion  25   b  of the fixed electrode member  25  and the left-hand end side projection  28   b  of the cylindrical electrode  28 , (3) the projection  28   a  at the right-hand end side of the cylindrical electrode  28  and the claw portion  29   b  of the fixed contact  29  (4) the contact between the disk portion  29   a  of the fixed contact  29  and the sliding arm  30   c  of the sliding contact  30 , (5) the electrical path from the claw portion  30   b  of the sliding contact  30  to the inner wall surface  10   d   1  of the developing roller  10   d . Thus, the application of the developing bias to the developing roller  10   d  is enabled. 
     Here, the electrical connection between the disk portion  29   a  of the fixed contact  29  and the sliding arm  30   c  of the sliding contact  30  is provided by a sliding contact, and therefore, there is liability that application of the developing bias may be influenced by the wearing of the sliding contact portion of the sliding contact (the sliding portion between the disk portion  29   a  and the sliding arm  30   c ) and by the damage of the sliding contact portion or the like, and it is preferable to apply electroconductive grease thereto. In such a case, the present environment is desirable in that sliding contact portion is disposed inside developing roller  10   d  so that it does not interfere with the mounting operation of the developing roller unit DU to the toner developing device frame  12 . In addition, the leakage of the electroconductive grease to the outside of the developing roller unit DU is not likely, and the scattered toner or dust are prevented from entering, and therefore, the property of the electroconductive grease can be maintained. Thus, the reliability of the establishment of the electrical conviction between the disk portion  29   a  of the fixed contact  29  and the sliding arm  30   c  of the sliding contact  30 , is improved. 
     The plurality of projections  10   c   2  provided at the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c  is effective to indicate the completion of insertion of the magnet  10   c  into the developing roller  10   d  when the developing roller unit DU is assembled, as described hereinbefore, and in addition, the following functions are provided. 
     When an impact is imparted to the developing roller unit DU in the axial direction (the axial direction of the developing roller  10   d ) during transportation or the like of the process cartridge B including the developing roller unit DU of the embodiment, the free end surface  10   c   21  of the projection  10   c   3  is abutted to the disk portion  30   a  of the sliding contact  30  fixed to the contact support  31  in the flange member  20   b . Therefore, the plastic deformation of the sliding arm  30   c  of the sliding contact  30  which may be caused by excessive force, can be prevented. Thus, the electrical contact mechanism of the fixed contact  29  to the disk portion  29   a  using the sliding arm  30   c  of the sliding contact  30  is improved in the reliability. 
     By the provisions of the plurality of projections  10   c   2  around the base portion of the thin left-hand shaft portion  10   c  of the magnet  10   c , the diameter of the shaft base portion can be expanded to improve the mechanical strength of the shaft base portion. Accordingly, even if the inpact due to drop-out of the cartridge or the like, the base portion of the left-hand shaft portion  10   c  is protected from being broken. In addition, the cylindrical electrode  28  of metal is engaged in the left-hand shaft portion  10   c   1 , and therefore, the strength of the shaft base portion is further improved. 
     The mounting of the magnet  10   c  of the cylindrical electrode  28  to the left-hand shaft portion  10   c   1  is desirably at a predetermined angle relative to the left-hand shaft portion  10   c   1  in order to assured the electrical connection between the left-hand end side projection  28   b  of the cylindrical electrode  28  and the contact portion  25   b  of the fixed electrode member  25  provided to the holder  24   b . Therefore, in this embodiment, an erroneous assembling preventing structure is provided to prevent mounting the cylindrical electrode  28  to the left-hand shaft portion  10   c   1  at an angle different from the predetermined angle. 
     Referring to FIGS. 2,  3 ,  14  and  16 , the description will be made as to the structure. 
     (Erroneous Assembling Preventing Structure for Mounting of a Cylindrical Electrode to the Left-hand Shaft Portion) 
     As shown in FIG. 2, to the trailing edge, at the righthand side, of the cylindrical portion  28   e  (engaging portion) of the cylindrical electrode  28 , there is provided a projection  28   a  at each of 3 positions, and also, there is provided at each of 3 positions recesses  10   c   22  (engaging portion) between the adjacent projections  10   c   2  at the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c , and the projection  28   a  and the recess  10   c   22  are engaged with each other (FIG.  3 ). 
     FIG. 14 is a schematic view illustrating an engaging relation between the projection  28   a  and the recess  10   c   22 . The left side in the Figure, the cylindrical electrode  28  is shown as being expanded, and the righthand side of the Figure similarly shows the projection  10   c   2  and the recess  10   c   22  of the magnet  10   c  which are hypothetically expanded. In FIG. 14, the projection  28   a  as to engaging portion of the cylindrical electrode  28  comprises three projections, namely, a first projection  28   aa , a second projection  28   ab , third projection  28   ac , wherein the righthand side second projection  28   ab  is disposed coaxially with the left-hand projection  28   b  of the cylindrical electrode  28 . The gaps among the projections  28   aa ,  28   ab ,  28   ac  are determined such that when the cylindrical electrode  28  is engaged with the left-hand shaft portion  10   c   1  of the magnet  10   c , the angles as seen from the axis of the left-hand shaft portion  10   c   1  between the first projection  28   aa  and the second projection  28   ab  and between third projection  28   ab  and the third projection  28   ac  are 130 degrees. Therefore, the angle between the third projection  28   ac  and the first projection  28   aa  is 100 degrees. 
     The recess  10   c   22  as to engaging portion of the magnet  10   c  comprises three recesses, namely, a first recess  10   c   22   a , a second recess  10   c   22   b , and a third recess  10   a   22   c , and gaps among recesses  10   c   22   a ,  10   c   22   b ,  10   a   22   c  are such that angles as seen from the axis of the left-hand shaft portion  10   c   1  between the first recess  10   c   22   a  and the second recess  10   c   22   b  and between the second recess  10   c   22   b  and the third recess  10   a   22   c  are 130 degrees, similarly to the cylindrical electrode  20 . Similarly, the angle between the third recess  10   c   22   c  and the first recess  10   c   22   a  is 100 degrees. 
     Therefore, the positions of the projection  28   a  of the cylindrical electrode  28  and the conditions of the recess  10   c   22  of the left-hand shaft portion  10   c   1  of the magnet  10   c  are aligned of the outer surface of the left-hand shaft portion  10   c,   1  and therefore, the cylindrical electrode  28  can be properly mounted to the left-hand shaft portion  10   c   1 . 
     Referring to FIG. 15, a description will be made as to the case in which the mounting angle of the cylindrical electrode  28  to the left-hand shaft portion  10   c   1  is erroneous. 
     The cylindrical electrode  28  is rotated  130  decrease as seen from the left-hand projection  28   b  side so that second projection  28   ab  of the cylindrical electrode  28  is engaged with the third recess  10   c   22   c  of the left-hand shaft portion  10   c   1 . 
     In this case, the first projection  28   aa  and the second projection  10   c   22   b  are engageable as long as the positional relation is concerned therebetween, but there is a 30 degrees deviation between the third projection  28   ac  and the first recess  10   c   22   a , because the design is such that angle between the first projection  28   aa  and the second projection  28   ab  and the angle between the second recess  10   c   22   b  and the third recess  10   c   22   c  are 130 degrees. So, if an attempt is made to telescope the cylindrical electrode  28  to the left-hand shaft portion  10   c   1 , the third projection  28   ac  abuts the projection  10   c   2  between the first recess  10   c   22   a  and the second recess  10   c   22   b , so that cylindrical electrode  28  is unable to be moved to the regular position of the left-hand shaft portion  10   c   1 . 
     Although not shown, the cylindrical electrode  28  is rotated from −130 degrees as seen from the left-hand projection  28   b  side in an attempt to engage the third projection  28   ac  of the cylindrical electrode  28  to the first recess  10   c   22   a  of left-hand shaft portion  10   c   1 , there is 30 degrees deviation between the first projection  28   aa  and the second recess  10   c   22   b . For this reason, whether cylindrical electrode  28  is telescoped to the left-hand shaft portion  10   c   1 , the first projection  28   aa  abuts the projection  10   c   2  between the first recess  10   c   22   a  and the second recess  10   c   22   b , so that cylindrical electrode  28  is unable to be moved to the regular position of the left-hand shaft portion  10   c   1 . 
     However, the cylindrical electrode  28  can be inserted to the regular position of the left-hand shaft portion  10   c   1  when the first of the projection  28   aa  is opposed to the first recess  10   c   22   a , and the second projection  28   ab  is opposed to the second recess  10   c   22   b , and the third projection  28   ac  is opposed to the third recess  10   a   22   c , of the outer surface of the left-hand shaft portion  10   c   1 . In other words, the cylindrical electrode  28  can be mounted to the left-hand shaft portion  10   c   1  only when the projections  28   aa ,  28   ab ,  28   ac  and the recesses  10   c   22   a ,  10   c   22   b ,  10   c   22   c  of the left-hand shaft portion  10   c   1  of the magnet  10   c  are aligned with each other on the outer surface. Therefore, the correct mounting of the cylindrical electrode  28  to the left-hand shaft portion  10   c   1  is assured. 
     Referring to FIG. 16, a description will be made as to a further modified example. In FIG. 16, the angles between adjacent ones of the projections  28   ad ,  28   ae ,  28   af  and the angles between adjacent ones of the recesses  10   c   22   d ,  10   c   22   e ,  10   c   22   f  are equal (120 degrees). A width  28   ae W of the second projection  28   ae  of the three projections  28   ad ,  28   ae ,  28   af  is larger than the widths h  28   ad W,  28   af W of the first third projections  28   ad ,  28   af . Correspondingly, the width  10   c   22   f W of the second recess  10   c   22   e  of the three recesses  10   c   22   d ,  10   c   22   e ,  10   c   22   f  is larger manner widths h  10   c   22   d W,  10   c   22   f W of the first and third recesses  10   c   22   d ,  10   c   22   f . With the positional relationship among the projections  28   ad ,  28   ae ,  28   af  and the recesses  10   c   22   d ,  10   c   22   e ,  10   c   22   f , they are all engaged when the three projections and the three recesses are engaged when the positions are aligned on the outer surface of the left-hand shaft portion  10   c   1 , and therefore, the cylindrical electrode  28  can be mounted correctly to the left-hand shaft portion  10   c   1 , and therefore, the cylindrical electrode  28  can be mounted correctly to the left-hand shaft portion  10   c   1 . 
     However, in the modified example, the width  28   ae W of the second projection  28   ae  is larger than the widths h  10   c   22   f W,  10   c   22   d W of the third recess  10   c   22   f  and the first recess  10   c   22   d.   
     
       
           28   ae &gt;&gt; 10   c   22   d W,  28   ae W&gt; 10   c   22   d W 
       
     
     Therefore, the second projection  28   ae  is unable to engage with either one of the recesses  10   c   22   d ,  10   c   22   f  other than the second recess  10   c   22   e . Thus, the cylindrical electrode  28  is unable to telescope to the regular position of the left-hand shaft portion  10   c   1  with any angle other than that shown in FIG.  16 . 
     In the modified example, therefore, the cylindrical electrode  28  can be mounted correctly to the left-hand shaft portion  10   c   1  only when the projections  28   ad ,  28   ae ,  28   af  of the are aligned with the recesses  10   c   22   d ,  10   c   22   e ,  10   a   22   f  of the left-hand shaft portion  10   c   1  of the magnet  10   c  on the outer surface of the left-hand shaft portion  10   c 1   . By doing so, the cylindrical electrode  28  can be mounted to the left-hand shaft portion  10   c   1  of the cylindrical electrode  28  with correct mounting angle. 
     In these embodiments, the cylindrical electrode  28  can be mounted to the left-hand shaft portion  10   c   1  only when the projections of the cylindrical electrode  28  are all aligned with the recesses of the left-hand shaft portion  10   c   1  of the magnet  10   c  on the outer surface of the left-hand shaft portion  10   c   1 , and therefore, the assembling easiness property of the cylindrical electrode  28  constituting a part of the contact portion for applying the developing bias to the developing roller is improved. 
     In these embodiments, the mounting angle to the left-hand shaft portion of the cylindrical electrode  28  is determined using the three projections and the three recesses, but the number of the projections and the number of the recesses are not limited to the number of these embodiments. 
     The above-described developing devices are summarized as follows. A developing device usable with an electrophotographic image forming apparatus (A) to develop an electrostatic latent image formed on an electrophotographic photosensitive member ( 7 ): 
     (a) a frame (toner developing device frame  12 ); 
     (b) a developing roller ( 10   d ) for developing the electrostatic latent image formed on an electrophotographic photosensitive member with a developer (toner); 
     (c) a magnet (magnet  10   c ) disposed in the developing roller having a shaft at each of one and the other ends, wherein the shaft is extended from an inside of the developing roller to an outside thereof; 
     (d) a first electroconductive portion extended in the longitudinal direction of one of the shaft at one of ends (left-hand shaft portion  10   c   1 ), the first electroconductive portion (cylindrical electrode  28 ) being extended from an inside of the developing roller to an outside thereof; 
     (e) a second electroconductive portion electrically connecting the first electroconductive portion with an inner surface (inner wall surface  10   d   1 ), the electroconductive portion being provided in the developing roller; 
     (f) a third electroconductive portion (fixed electrode member  25 ) provided in the frame, the third electroconductive portion including a first electrical contact portion (contact portion  25   b ) at one longitudinal end of the developing roller, a second electrical contact portion (exposed portion  25   a ) provided that position different from the position of the first electrical contact portion, for electric connection with a main assembly side electrical contact (apparatus side contact  26 ) provided in the main assembly  14  of the electrophotographic image forming apparatus when the developing device is mounted to the main assembly  14  of the electrophotographic image forming apparatus, wherein the first electrical contact portion is electrically connected with the first electroconductive portion; 
     Wherein the first electroconductive portion is electrically connected with the second electroconductive portion in the developing roller, and is electrically connected to the first electrical contact portion in an outside of the developing roller. 
     The developing roller is provided at its one end with a flange (shaft portion  20   b   1 ) projected outwardly of the developing roller in the longitudinal direction of the developing roller; The flange covers the outside portion (cylindrical portion  28   e ) of the developing roller  10   d  leaving the free end portion of the first electroconductive portion (left-hand end side projection  28   b ). 
     The flange is supported rotatably on the frame. 
     The free end portion of the first electroconductive portion (projection  28   b  at the left-hand end side) is contacted to the first electrical contact portion. 
     The first electroconductive portion has a cylindrical portion (cylindrical portion  28   e ). The cylindrical is engaged with the shaft. 
     A projected portion (projection  28   a  at the right-hand end side) projected from a rear end of the cylindrical portion is engaged with a recess ( 10   c   22 ) of the shaft. By this, rotation of the cylindrical portion is limited relative to the shaft. 
     The first electroconductive portion has a disk (disk portion  29   a ) electrically connected with the cylindrical portion. The disk is provided with a hole ( 29   c ). The shaft benefits the hole. 
     The second electroconductive portion these fixed inside the developing roller. The second electroconductive portion includes a first contact portion (claw portion  30   b ) contacted to the inner surface of the developing roller  10   d , and a second contact portion (sliding arm  30   c ) elastically contacted to the first electroconductive portion. 
     The second contact portion is elastically in sliding contact to the surface (disk portion surface  29   a   1 ) of a disk contacted electrically to the cylindrical of the first electroconductive. The disk has a hole. The shaft penetrates the hole. 
     The second contact portion is in sliding contact with a peripheral surface of the cylindrical portion a (disk portion surface  29   a   1 ) of the first electroconductive portion. 
     The first the electroconductive portion receives an elastic force in a radial direction of the shaft by the first electrical contact portion. 
     The free end portion of the prior is D-cut shape. The D-cut shape portion is engaged with a hole (supporting hole  24   b   1 ) of the frame. The frame end portion of the first electroconductive portion (the projection  28   b  at the left-hand end) these at an arcuate portion ( 10   c   31 ) of the D-cut shape. The 3 end portion of the first electroconductive portion ( 28 ) receives an elastic force by the first electrical contact portion in the direction toward the flat portion ( 10   c   32 ) of the D-cut shape from the arcuate portion of the D-cut shape. 
     The first electroconductive portion receives an elastic force in the axial direction of the should by the second electroconductive portion. 
     The process cartridges (B) of these embodiments are summarized as follows. 
     (a) an electrophotographic photosensitive member ( 7 ); 
     (b) a frame (toner developing device frame  12 ); 
     (c) a developing roller ( 10   d ) for developing the electrostatic latent image formed on an electrophotographic photosensitive member with a developer (toner); 
     A magnet (magnet  10   c ) disposed in the developing roller having a shaft at each of one and the other ends, wherein the shaft is extended from an inside of the developing roller to an outside thereof; 
     A first electroconductive portion extended in the longitudinal direction of one of the shaft at one of ends (left-hand shaft portion  10   c   1 ), the first electroconductive portion (cylindrical electrode  28 ) being extended from an inside of the developing roller to an outside thereof; 
     A second electroconductive portion electrically connecting the first electroconductive portion with an inner surface (inner wall surface lodl), the electroconductive portion being provided in the developing roller; 
     A third electroconductive portion (fixed electrode member  25 ) provided in the frame, the third electroconductive portion including a first electrical contact portion (contact portion  25   b ) at one longitudinal end of the developing roller, a second electrical contact portion (exposed portion  25   a ) provided that position different from the position of the first electrical contact portion, for electric connection with a main assembly side electrical contact (apparatus side contact  26 ) provided in the main assembly  14  of the electrophotographic image forming apparatus when the developing device is mounted to the main assembly  14  of the electrophotographic image forming apparatus, wherein the first electrical contact portion is electrically connected with the first electroconductive portion; 
     Wherein the first electroconductive portion is electrically connected with the second electroconductive portion in the developing roller, and is electrically connected to the first electrical contact portion in an outside of the developing roller. 
     The electric energy supply parts (sliding contact  30 ) of these embodiments are summarized as follows. 
     An electric energy supply part for supplying developing bias voltage to a developing roller ( 10   d ) from the main assembly ( 14 ) of the electrophotographic image forming apparatus, wherein the developing roller develops an electrostatic latent image formed on an electrophotographic photosensitive member ( 7 ) width ( 7 ), the developing roller has a magnet (magnet  10   c ) therein; 
     (a) a base (disk portion  30   a ) having a hole (through hole  30   d ) at the center never, wherein when the electric energy supply part is mounted into the developing roller, a shaft (left-hand shaft portion  10   c   1 ) of a magnet penetrates the hole; 
     (b) a first contact portion (claw portion  30   b ) for contacting to the inner surface of the developing roller; 
     (c) a first electroconductive portion (cylindrical electrode  28 ) extended along the shaft and a second contact portion (sliding arm  30   c ) for contacting elastically in the axial direction of the shaft. 
     The first electroconductive portion is electrically connected with the second electroconductive portion in the developing roller, and is electrically connected to the first electrical contact portion in an outside of the developing roller. The first electrical contact portion is disposed at one longitudinal end side of the developing roller. The electrical contact portion is electrically connected with a second electrical contact portion (exposed portion  25   a ) for connection with a main assembly side electrical contact (apparatus side contact  26  connection) provided in the main assembly of the electrophotographic image forming apparatus when the developing device is mounted to the main assembly of the electrophotographic image forming apparatus. 
     An electric energy supply part for applying a developing bias voltage to the developing roller ( 10   d ) of the developing device from the main assembly ( 14 ) of the electrophotographic image forming apparatus, wherein said developing device develops detachably electrostatic latent image formed on the electrophotographic photosensitive member ( 7 ), the electric energy supply part comprising: 
     (a) (a) a frame (toner developing device frame  12 ); 
     (b) a magnet (magnet  10   c ) disposed in the developing roller having a shaft at each of one and the other ends, wherein the shaft is extended from an inside of the developing roller to an outside thereof; 
     (c) a first electroconductive portion extended in the longitudinal direction of one of the shaft at one of ends (left-hand shaft portion  10   c   1 ), the first electroconductive portion (cylindrical electrode  28 ) being extended from an inside of the developing roller to an outside thereof; 
     (d) a third electroconductive portion (fixed electrode member  25 ) provided in the frame, the third electroconductive portion including a first electrical contact portion (contact portion  25   b ) at one longitudinal end of the developing roller, a second electrical contact portion (exposed portion  25   a ) provided that position different from the position of the first electrical contact portion, for electric connection with a main assembly side electrical contact (apparatus side contact  26 ) provided in the main assembly  14  of the electrophotographic image forming apparatus when the developing device is mounted to the main assembly  14  of the electrophotographic image forming apparatus; 
     the electric energy supply part comprising: 
     (A) a base(disk portion  30   a ) having a center hole (through hole  30   d ), wherein when the electric energy supply part is mounted into the developing roller, a shaft provided at the one end is penetrated through the hole; 
     (B) a first contact portion (claw portion  30   b ) for contact to the inner surface of the developing roller; 
     (C) and a second contact portion (sliding arm  30   c ) for elastic contact with first electroconductive portion (fixed contact  29 ) extended along the shaft in the axial direction of the shaft. 
     The base is circular, and the first contact portion is elastic. It is detected outwardly in the radial direction from the peripheral surface of the base. 
     The second contact portion is elastic. It is detected from the peripheral surface of the base in a direction crossing with the radial direction. 
     The material of the electric energy supply part is copper alloy, stainless steel alloy or spring steel. 
     The electric energy supply parts (fixed contact  29 ) of these embodiments are summarized as follows. 
     An electric energy supply part for supplying developing bias voltage to a developing roller ( 10   d ) from the main assembly ( 14 ) of the electrophotographic image forming apparatus, wherein the developing roller develops an electrostatic latent image formed on an electrophotographic photosensitive member ( 7 ) width ( 7 ), the developing roller has a magnet (magnet  10   c ) therein; 
     (a) a base (disk portion  30   a ) having a hole (through hole  30   d ) at the center never, wherein when the electric energy supply part is mounted into the developing roller, a shaft (left-hand shaft portion  10   c   1 ) of a magnet penetrates the hole; 
     (b) a contact portion (claw portion  29   b ) for elastic contact with the first electroconductive portion (cylindrical electrode  28 ) which is extended in the longitudinal direction of the shaft provided in said base to electrically connect therewith. 
     The contact portion is extended around the hole, and the contact portion is provided by bending a part of the base. 
     The contact portion is provided at each of three positions around the hole. 
     An electric energy supply part for supplying a developing bias to a developing roller ( 10   d ) of an electric energy supply part from a main assembly ( 14 ) of the electrophotographic image forming apparatus, wherein the developing device develops an electrostatic latent image formed on an electrophotographic photosensitive member ( 7 ), the developing device comprising: 
     (a) a frame (toner developing device frame  12 ); 
     (b) a magnet (magnet  10   c ) disposed in the developing roller having a shaft at each of one and the other ends, wherein the shaft is extended from an inside of the developing roller to an outside thereof; 
     (c) a first electroconductive portion extended in the longitudinal direction of one of the shaft at one of ends (left-hand shaft portion  10   c   1 ), the first electroconductive portion (cylindrical electrode  28 ) being extended from an inside of the developing roller to an outside thereof; 
     (d) a third electroconductive portion (fixed electrode member  25 ) provided in the frame, the third electroconductive portion including a first electrical contact portion (contact portion  25   b ) at one longitudinal end of the developing roller, a second electrical contact portion (exposed portion  25   a ) provided that position different from the position of the first electrical contact portion, for electric connection with a main assembly side electrical contact (apparatus side contact  26 ) provided in the main assembly  14  of the electrophotographic image forming apparatus when the developing device is mounted to the main assembly  14  of the electrophotographic image forming apparatus; 
     The electric energy supply part comprising: 
     (A) a base (disk portion  30   a ) having a center hole (through hole  30   d ), wherein when the electric energy supply part is mounted into the developing roller, a shaft provided at the one end is penetrated through the hole; 
     (B) a contact portion (claw portion  29   b ) for elastic and electric contact with the first electroconductive portion (cylindrical electrode  28 ) extended in the longitudinal direction of said shaft provided in said base, wherein the contact portion is extended around the hole, and the contact portion is provided by bending a part of the base. 
     The contact portion is provided at each of three positions around the hole. 
     The developing roller and the electrophotographic photosensitive member are unified into a cartridge which is mounted in a process cartridge which is detachably mountable to the main assembly of the electrophotographic image forming apparatus. 
     The base is circular. The hole is circular. A movement in a circumferential direction of the base is limited by engagement of the contact portion to the shaft. The material of the electric energy supply part is copper alloy, stainless steel alloy or spring steel. # 
     As described in the foregoing, with the developing device and the process cartridge, the sliding contact portion is provided within the developing roller  10   d  by the fixed contact  29  and the sliding contact  30 , so that sliding contact portion is protected from dust or other foreign matter. Additionally, when the electroconductive grease is applied to the sliding contact portion for the purpose of improvement of the reliability in the sliding contact portion, the electroconductive grease is protected from insurance of dust or foreign matter, so that reliability of the sliding contact portion is improved, because the possible deterioration of the performance of the electroconductive grease is prevented. 
     Furthermore, the sliding arm  30   c  of the sliding contact  30  constituting the sliding contact portion is contacted to be disk portion  29   a  of the fixed contact  29  in the axial direction of the developing roller  10   d , and therefore, the magnet  10   c  supported of the toner developing device frame  12  with play in the axial direction of the developing roller  10   d  is urged unidirectionally in the axial election in the toner developing device frame  12  on which it is supported, so that positional accuracy of the magnet  10   c  relative to the toner developing device frame  12  is improved. 
     Moreover, the D-cut  10   c   3  of the left-hand shaft portion  10   c   1  of the magnet  10   c  is urged toward the flat portion  10   c   32  from the arcuate portion  10   c   31  by the projection  28   b  of the cylindrical electrode  28  through the contact portion  25   b  of the fixed electrode member  25 , so that play in the engagement between the supporting hole  24   b   1  of the holder  24   b  and the D-cut  10   c   3  of the left-hand shaft portion  10   c   1  of the magnet  10   c  in the radial direction of the magnet  10   c . Therefore, the accuracy of positioning of the magnet  10   c  relative to the holder  24   b  is improved. 
     Since the sliding contact  30  is fixed flange member  20   b  through the insulative contact support  31  having the cylindrical portion  31   a  engaged with the hole  20   b   1  of the flange member  20   b  and the through-hole  31   c  through which the left-hand shaft portion  10   c   1  of the magnet l 0   c  penetrates, the sliding contact  30  can be disposed coaxially with the rotation axis of the developing roller  10   d , and the sliding track of the sliding contact  30  relative to the fixed contact  29  can be made a circle coaxial with the rotation axis of the developing roller. Therefore, the sliding motion of the sliding contact  30  relative to the fixed contact  29  is stabilized, and therefore, the reliability of the sliding contact portion is improved. 
     The cylindrical electrode  28  is telescoped to the left-hand shaft portion  10   c   1  to such that left-hand end side projection  28   a  is engaged with the recess  10   c   22  between the adjacent projections  10   c   2  provided at the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c , and therefore, the indexing, in the rotational direction, of the cylindrical electrode  28  relative to the left-hand shaft portion  10   c   1  of the magnet  10   c  (the correct positioning of the cylindrical electrode  28  in the rotational angle of the developing roller  10   d ) is possible. Therefore, the contact between the projection  28   a  of the cylindrical electrode  28  and the claw portion  29   b  of the fixed contact  29  is assured. 
     In addition, the projected portion  28   a  projected from the trailing edge of the cylindrical electrode  28  is engaged with the recess  10   c   22  provided at the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c , and the projected portion  28   a  and the recess  10   c   22  are constituted such that mounting angle (positioning in the circumferential direction) of the cylindrical electrode  28  relative to the left-hand shaft portion  10   c   1 , and therefore, the cylindrical electrode  28  can be mounted to the left-hand shaft portion  10   c   1  at correct mounting angle. The outer diameter of the projection  10   c   2  provided at the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c  is larger than the outer diameter of the projection  28   a  provided at the right-hand end side of the cylindrical portion  28   e  of the cylindrical electrode  28  and is smaller the then rotation track of the sliding contact portion between the sliding arm  30   c  of the sliding contact  30  and the disk portion  29   a  of the fixed contact  29 , and therefore, the sliding contact portion between the sliding arm  30   c  of the sliding contact  30  and the disk portion  29   a  of the fixed contact  29  can be protected by the projection  10   c   2  of the magnet  10   c , and in addition, the sliding function between the sliding arm  30   c  of the sliding contact  30  and then disk portion  29   a  of the fixed contact  29  is not deteriorated. In addition, the strength of the shaft base portion of the magnet  10   c  is improved. 
     The projection  10   c   2  provided at the base portion of the left-hand shaft portion  10   c   1  of the magnet  10   c  is determined such that height of the projection  10   c   2  measured in the axial direction when the fixed contact  29  is closely contacted to the shaft base portion  10   c   5  is higher than the free end of the claw portion of the claw portion  29   a  of the fixed contact  29 , and therefore, even if the process cartridge B receives impact during transportation thereof, in the axial direction of the developing roller  10   d , the free end surface  10   c   2  of the projection  10   c   2  is abutted to the disk portion  30   a  of the sliding contact  30 . Therefore, the contact portion between the fixed contact  29  and the cylindrical electrode  28  is protected, and in addition, the sliding contact portion between the sliding arm  30   c  of the sliding contact  30  and the disk portion  29   a  of the fixed contact  29  is protected from receiving excessive force. # 
     The fixed contact  29  is assuredly connected electrically with the cylindrical electrode  28 , since the left-hand shaft portion  10   c   1  of the magnet  10   c  penetrates the through hole  29   c  of the through hole  29   c , and claw portions  29   b  disposed around the through hole  29   c  are elastically contacted to the cylindrical electrode  28  extended in the longitudinal direction of the left-hand shaft portion  10   c   1  to be electrically connected to the cylindrical electrode  28 . 
     The sliding contact  30  comprises the through hole  10   d  through which the left-hand shaft portion  10   c  of the magnet  10   c  penetrates, the disk portion  30   a  formed around the through hole  10   d , a plurality of claw portions  30   b  extended radially outwardly from the disk portion  30   a  and bent toward downstream with respect to the inserting direction of the magnet  10   c  to be contacted to the inner wall surface  10   d   1  of the developing roller  10   d , and the sliding arm  30   c  extended in a spiral line about a line perpendicular to the surface  30   a   1  of the disk through the center of the disk portion  30   a  and elastically contacted to the disk portion  29   a  of the fixed contact  29 . Since the sliding arm  30   c  is elastically contacted to the disk portion  29   a  of the fixed contact  29 , so that magnet  10   c  can be urged in the axial direction of the developing roller  10   d  through the fixed contact  29 , and therefore, the play in the axial direction of the magnet  10   c  relative to the developing roller  12   d  can be eliminated, thus improving the positional accuracy of the magnet  10   c . Additionally, even if a force is applied in such a direction that sliding contact  30  is away from the inside of the developing roller  10   d , the force against it is provided, and furthermore, the electrical connection with the developing roller  10   d  is assured. Since the contact pressure between the sliding arm  30   c  and the disk portion  29   a  of the fixed contact  29  is imparted substantially in the axial direction of the developing roller  10   c , so that contact support  31  can be closely contacted to the inner end surface  20   b   3  of the flange member  20   b  by the urging of the magnet  10   c  in the axial direction and the reaction. 
     In the foregoing embodiments, the projection  28   b  at the left side of the cylindrical electrode  28  is parallel with the arcuate portion  30   c   31  of the D-cut  10   c   3  of the magnet  10   c  (FIG.  2 ), but as shown in FIGS. 12 and 13, the end of the projection  28   b  of the cylindrical electrode  28  may be bent inwardly into a bent portion  28   b   1 , which is locked to the beveling portion  30   c   33  provided at the free end of the arcuate portion  30   c   31  of the D-cut  10   c   3  of the magnet  10   c . By doing so, the movement of the cylindrical electrode  28  relative to left-hand shaft portion  10   c   1  of the magnet  10   c  can be assuredly prevented, and in addition, the end surface  28   d  of the cylindrical portion  28   e  can be easily aligned with the bottom surface  10   c   4  of the left-hand shaft portion  10   c   1 . 
     (Other Embodiments) 
     In the foregoing embodiments, the developing device and/or the electric energy supply part are used for a process cartridge for forming a monochromatic image, but the developing device and/or the electric energy supply part according to the present invention are usable with a cartridge for forming multi color images ( 2 color image,  3 color image, full-color or the like) in which a plurality of the developing means are provided. 
     In the foregoing, the process cartridge has been described as being for formation of a monochromatic image, but the process cartridge is is usable for multi-color image ( 2 color image,  3 color image or full-color) in which a plurality of developing means are provided. # 
     In the above-described embodiment, the electrophotographic photosensitive member has been described as photosensitive drum, but the electrophotographic photosensitive member is not limited to such a photosensitive drum, but the following is usable. The photosensitive member may be a photoconductor which may be an amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, organic photoconductor (OPC) or the like. The photosensitive member may be in the form of a drum, a belt or another rotatable member, or a sheet, or the like. Generally, however, a drum or a belt is used, and in the case of a drum type photosensitive member, a cylinder of aluminum alloy or the like is coated with a photoconductor by evaporation or application or the like. 
     The structure of the charging means described in the foregoing is of a so-called contact type charging method, but a known charging means comprising a tungsten wire which is enclosed width metal shield of aluminum or the like at three sides, wherein positive or negative ions generated by application of a high voltage to said tungsten wire are directed to the surface of the photosensitive drum to uniformly charged the surface, is usable. The charging means may be a roller type as described in the foregoing, a blade type (charging blade), a pad type, a block type, a rod type, a wire type or the like. 
     As for a cleaning method for removing toner remaining on the photosensitive drum, a blade, a fur brush, a magnetic brush or the like is usable. 
     The process cartridge, for example, comprises an electrophotographic photosensitive member and at least one process means. As for the types of the process cartridge, there are, in addition to those disclosed hereinbefore, a type in which, for example, an electrophotographic photosensitive member, a developing means and a charging means are unified integrally into a cartridge which is detachably mountable to the main assembly of the electrophotographic image forming apparatus, a type in which an electrophotographic photosensitive member and a developing means are unified integrally into a cartridge which is detachably mountable to a main assembly of apparatus, a type in which an electrophotographic photosensitive member, a developing means, a charging means and cleaning means are unified integrally into a cartridge which is detachably mountable to a main assembly of an electrophotographic image forming apparatus, they tied in which an electrophotographic photosensitive member and two or more of the process means are combined integrally into a cartridge which is detachably mountable to a main assembly of an electrophotographic image forming apparatus. 
     The process cartridge may contain an electrophotographic photosensitive member and at least one of charging means, developing means and cleaning means as a unit which constitutes a cartridge which is detachably mountable to a main assembly of an electrophotographic image forming apparatus. The process cartridge is mounted to or demounted from the main assembly of the apparatus by the user. This means that maintenance of the apparatus is carried out, in effect, by the user. 
     In the foregoing environment, a laser beam printer has been described in the foregoing as an example of the electrophotographic image forming apparatus, but the present invention is not limited thereto, and the present invention is applicable to an electrophotographic copying machine, a facsimile machine, a facsimile machine or the like of an electrophotographic type. 
     While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purpose of the improvements or the scope of the following claims.