next , the process cartridge , and the electrophotographic image forming apparatus employing the process cartridge , in the first embodiment of the present invention will be described with reference to the appended drawings . first , the general structure of the multicolor image forming apparatus will be described referring to fig1 . fig1 is a vertical sectional view of a full - color laser beam printer , which is one of the various forms of a multicolor image forming apparatus , showing the general structure thereof . the main assembly 100 of the image forming apparatus ( which hereinafter will be referred to simply as apparatus main assembly ) shown in fig1 is equipped with four electrophotographic photosensitive drums 1 ( 1 a , 1 b , 1 c , and 1 d ), which are electrophotographic photosensitive members . these electrophotographic photosensitive drums 1 ( which hereinafter will be referred to as photosensitive drums 1 ) are in the form of a drum , and are vertically stacked in parallel with each other . they are rotationally driven by a driving means ( unshown ) in the counterclockwise direction of the drawing . in the adjacencies of the peripheral surface of each of the photosensitive drums 1 , a charging apparatus 2 ( 2 a , 2 b , 2 c , and 2 d ), a developing apparatus 4 ( 4 a , 4 b , 4 c , and 4 d ), an electrostatic transferring apparatus 5 ( 5 a , 5 b , 5 c , and 5 d ), a cleaning apparatus 6 ( 6 a , 6 b , 6 c , and 6 d ) are disposed in the listed order in terms of the rotational direction of the photosensitive drum 1 . the charging apparatus 2 uniformly charges the peripheral surface of the photosensitive drum 1 . the developing apparatus 4 develops an electrostatic latent image formed on the peripheral surface of the photosensitive drum 1 ; it turns the electrostatic latent image into a toner image ( image formed of toner ) by adhering toner to the electrostatic latent image . the electrostatic transferring apparatus 6 transfers the toner image on the photosensitive drum 1 onto a recording medium s . the cleaning apparatus 6 removes the toner remaining on the peripheral surface of the photosensitive drum after the transfer of the toner image . the photosensitive drum 1 , charging apparatus 2 , developing apparatus 4 , and cleaning apparatus 6 are integrally disposed in a cartridge , making up a process cartridge 7 ( which hereinafter will be referred to “ cartridge ”). in the rear portion of the apparatus main assembly , scanner units 3 ( 3 a , 3 b , 3 c , and 3 d ) are disposed , each of which is for selectively exposing the numerous points of the peripheral surface of the corresponding photosensitive drum 1 to form a latent image on the photosensitive drum 1 . the electrostatic transferring apparatus is provided with an electrostatic transfer belt 11 , which is positioned so that it opposes all the photosensitive drums 1 a , 1 b , 1 c , and 1 d . the electrostatic transfer belt 11 circularly moves in contact with all the photosensitive drums 1 a , 1 b , 1 c , and 1 d . as the material for the electrostatic transfer belt 11 , resin film , or multilayer film made up a substrate layer formed of rubber and a resin layer layered on the substrate layer , is used . the electrostatic transfer belt 11 is stretched around a driver roller 13 , follower rollers 14 a and 14 b , and a tension roller 15 . it is circularly moved , with the recording medium s electrostatically adhered to the outward surface ( in terms of the loop which belt 11 forms ) of the electrostatic transfer belt 11 , with the application of bias to an electrostatic adhesion roller 22 , so that the recording medium s is placed in contact with each of the abovementioned photosensitive drums 1 . thus , the recording medium s is conveyed by the electrostatic transfer belt 11 to the transfer station , in which the toner image on the photosensitive drum 1 is transferred onto the recording medium s . within the loop of this electrostatic transfer belt 11 , transfer rollers 12 ( 12 a , 12 b , 12 c , and 12 d ) are disposed in parallel , in contact with the inward surface ( in terms of loop of the transfer belt ), opposing the four photosensitive drums 1 a , 1 b , 1 c , and 1 d , respectively . as such bias that is opposite in polarity to the toner image is applied to each of the transfer rollers 1 , the toner image on the corresponding photosensitive drum 1 is transferred onto the recording medium s . a feeding station 16 is a portion for feeding the recording medium s into the apparatus main assembly , and conveying it to the image formation portion . the feeding station 16 and abovementioned electrostatic transfer belt 11 make up a conveying means for conveying the recording medium s . the feeding station 16 holds a feeder cassette 17 , in which multiple recording mediums s are stored . the feeder cassette 17 is removably mounted in the feeding station 16 . in an image forming operation , a feeder roller 18 ( roller with semicircular cross section ) and a registration roller 19 are rotationally driven in synchronism with the progression of the image forming operation . more specifically , as the feed roller 18 is rotationally driven , the recording mediums s in the feeder cassette 17 are fed into the main assembly while being separated one by one . each of the recording mediums fed into the main assembly is conveyed by the registration roller 19 to the electrostatic transfer belt 11 , in synchronism with the rotation of the electrostatic transfer belt 11 , so that the arrival of the theoretical transfer start line on the recording medium s at the transfer station coincides with the arrival , at the transfer station , of the leading edge of the toner image on the photosensitive drum 1 . a fixing station 20 is a station in which the multiple toner images , different in color , having just been transferred onto the recording medium s , are fixed . it is made up of a rotatable heat roller 21 a , and a rotatable pressure roller 21 b which is kept pressed on the heat roller 21 a to apply heat and pressure to the recording medium s . to describe the image forming operation , the cartridges 7 a , 7 b , 7 c , and 7 d are sequentially driven in coordination with the printing timing , being thereby rotated in the counterclockwise direction . further , the scanner units 3 are rotationally driven in succession in response to the rotation of the corresponding photosensitive drums 1 . as a result , an electrostatic latent image is formed on each of the photosensitive drums 1 , the peripheral surface of which has been uniformly charged . the latent image is developed by the developing apparatus 4 into a toner image . in synchronism with the progression of the formation of the toner image in each of the image forming stations , the recording medium s is sequentially conveyed by the electrostatic transfer belt 11 to each of the areas , in which the recording medium s opposes the photosensitive drum 1 . as transfer bias is applied to the transfer rollers 12 ( 12 a , 12 b , 12 c , and 12 d ) which oppose the photosensitive drums 1 , one for one , with electrostatic transfer belt 11 remaining pinched between the photosensitive drums 1 and transfer rollers 12 , the developer images , different in color , on the photosensitive drums 1 are transferred in layers onto the recording medium s . as a result , a color image is effected on the recording medium s . the recording medium s bearing the transferred four toner images different in color is separated from the electrostatic transfer belt 11 with the utilization of the curvature of the driver roller 13 , and is conveyed into the fixation station 20 , in which the toner images are thermally fixed to the recording medium s . thereafter , the recording medium s is discharged by a discharge roller 23 from the main assembly through a recording medium outlet 24 , with the image bearing surface of the recording medium s facing downward . next , referring to fig3 and 4 , the cartridge in this embodiment will be described in detail . fig2 and 3 are sectional and perspective views , respectively , of the cartridge 7 which is holding toner . incidentally , the cartridges 7 a , 7 b , 7 c , and 7 d , which hold yellow , magenta , cyan , and black toners , respectively , are the same in structure . each cartridge 7 is made up of a cleaner unit 50 and a development unit 4 . the cleaner unit 50 comprises : the photosensitive drum 1 , charging means , and cleaning means . the development unit 4 makes up the developing apparatus for developing an electrostatic latent image on the photosensitive drum 1 . the cleaner unit 50 has a cleaning unit frame 51 , to which the photosensitive drum 1 is rotatably attached , with the bearings placed between the photosensitive drum 1 and cleaning unit frame 51 . in the adjacencies of the peripheral surface of the photosensitive drum 1 , a primary charging apparatus 2 is disposed , which is for uniformly charging the photosensitive layer as the surface layer of the photosensitive drum 1 . also in the adjacencies of the peripheral surface of the photosensitive drum 1 , a cleaning blade 60 ( which hereinafter will be referred to as “ blade ”) is disposed , which is for removing the developer ( residual toner ) remaining on the peripheral surface of the photosensitive drum 1 after the image transfer . the residual toner removed from the peripheral surface of the photosensitive drum 1 by the blade 60 is stored in a residual toner bin 55 located above the blade 60 . the development unit 4 is made up of : a development sleeve 40 which rotates in the direction indicated by an arrow mark while maintaining a minute gap from the photosensitive drum 1 ; and development unit frames 45 a and 45 b in which toner is held . the development unit frames 45 a and 45 b are joined with each other ( welded to each other by ultrasonic welding or the like ), making up a developing means container unit 46 . the development sleeve 40 is rotatably supported by a developing means container unit 46 with the placement of bearings between the development sleeve 40 and the unit 46 . in the adjacencies of the development sleeve 40 , a toner supply roller 34 and a development blade 44 are disposed in contact with the development sleeve 40 . the toner supply roller 43 is rotated in the direction indicated by an arrow mark . further , within the developing means container unit 46 , a toner conveyance mechanism 42 , which is for conveying the toner in the developing means container unit 46 to the toner supply roller 43 while stirring the toner is disposed . as for the sequence in which the development unit 40 is assembled , first , the developing means unit 46 and cleaner unit 50 are positioned so that a pair of connective holes 47 with which the lengthwise ends of the unit 46 is provided one for one , align with the supporting holes 52 with which the lengthwise ends of the cleaner unit frame 51 , one for one . then , a pin 49 is inserted through the connective hole 47 and supporting hole 52 , at both lengthwise ends of the development unit 4 , effecting thereby the cartridge 7 structured so that the development unit 4 is suspended from the cleaner unit 50 , and also , so that the development unit 4 is allowed to pivotally move relative to the cleaner unit 50 . further , the development unit 4 is kept pressed toward the cleaner unit 50 by compression springs ( unshown ) so that even if the developing unit 4 pivots about the axial lines of the supporting holes 52 , the development sleeve 40 remains in contact with the peripheral surface of the photosensitive drum 1 . next , referring to fig4 , the portion of the apparatus main assembly 100 , into which the cartridges 7 are mounted , will be described ( this portion hereafter will be referred to as “ cartridge bay ”). as shown in fig4 , the apparatus main assembly 100 is provided with a front door 101 , which is rotatably attached to the apparatus main assembly 100 . behind the front door 101 , the electrostatic transferring apparatus 5 is rotatably disposed . it is when the front door 101 and electrostatic transferring apparatus are in the open position that the cartridges 7 are removably mountable in the apparatus main assembly 100 . the cartridge 7 is provided with a pair of handgrips 90 , which are located at the lengthwise ends of the cartridge 7 , near the photosensitive drum supporting portions of the cartridge 7 . when the cartridge 7 is mounted or removed , the handgrips 90 are protruding toward the front door 101 . the lengthwise end surfaces of the cartridge 7 are provided with a pair of insert guides 53 ( fig3 as well as fig4 ), one for one , which engage with a pair of guide rails 102 and 103 , one for one , located in the apparatus main assembly 100 , enabling the cartridge 7 to be mounted into , or removed from the apparatus main assembly 100 . as a user finishes mounting the cartridge 7 and closes the front door 101 , the closure of the front door 101 applies pressure ( unshown ) to the cartridge 7 . then , the cartridge 7 is properly positioned relative to the apparatus main assembly 100 by the driving force transmitted to the cartridge 7 to form an image . the cartridge 7 in this embodiment is provided with a memory 200 for storing such information as the lot number of the cartridge 7 , the characteristics of an image forming apparatus , the characteristics of the processing means , etc . next , referring to fig3 , and 7 , this memory will be described . incidentally , fig5 is a perspective view of the memory itself , and fig7 is a perspective view of the electrical contacts , and their adjacencies , in the apparatus main assembly 100 . the cartridge 7 in this embodiment sends the information in the memory 200 to the apparatus main assembly 100 , providing the control portion ( unshown ) of the apparatus main assembly 100 with the information regarding the cartridge 7 , such as the history of the usage of the cartridge 7 , according to which the control portion controls the image forming process . it also receives information from the apparatus main assembly 100 . therefore , images are formed under optimal conditions . referring to fig5 , the memory 200 in this embodiment is attached to one of the primary surfaces of the memory substrate 202 , which is a thin and rectangular member . the memory substrate 202 is provided with a pair of electrical contacts 201 a and 201 b , which are on the opposite surface from the surface having the memory 200 . in other words , the memory substrate 202 also serves as an electrical contact substrate . the memory substrate 202 is attached to a contact supporting means , with which the cleaner unit 50 is provided . the contact supporting means will be described later . as the cartridge 7 is mounted into the apparatus main assembly 100 , the electrical contacts 201 a and 201 b of the cartridge 7 are placed in contact with a pair of electrical contacts 104 a and 104 b , respectively , of the apparatus main assembly 100 , establishing electrical connection between the cartridge 7 and apparatus main assembly 100 , enabling the information in the memory 200 to be transmitted to the apparatus main assembly 100 through the electrical contacts 104 a and 104 b . the memory substrate 202 is attached to the cleaner unit frame 51 so that the electrical contacts 201 a and 201 b of the cartridge 7 face outward of the cartridge 7 . the memory substrate 202 is attached to the cleaner unit frame 51 so that as the cartridge 7 is inserted into the apparatus main assembly 100 , the electrical contacts 201 a and 201 b of the cartridge 7 face roughly downstream , in terms of the direction in which the cartridge 7 is inserted into the apparatus main assembly 100 . further , in this embodiment , the cleaner unit 50 , which holds the memory substrate 202 , is provided with a groove 203 for accurately positioning the electrical contacts . the groove 203 is located next to the electrical contacts 201 a and 201 b of the cartridge 7 , in terms of the lengthwise direction of the cleaning means unit 50 . this groove 203 functions as an electrical contact positioning portion ( which hereinafter may be referred to as contact positioning groove ). more specifically , as the cartridge 7 is mounted into the apparatus main assembly 100 , the positioning portion , with which the apparatus main assembly 100 is provided to properly position the electrical contacts 201 a and 201 b relative to the electrical contacts 104 a and 104 b , respectively , of the apparatus main assembly 100 , engage into the contact positioning groove 203 . next , referring to fig6 - 8 , the structure for attaching the memory substrate 202 to the cartridge 7 , and removing the memory substrate 202 from the cartridge 7 , will be described . fig6 ( a )- 6 ( d ) are perspective views of the memory 202 , and the memory slots of the cartridge 7 , sequentially showing the steps of the method for attaching the memory substrate 202 to the cartridge 7 , and the steps of the method for removing the memory substrate 202 from the cartridge 7 . fig8 ( a ) and 8 ( b ) are sectional views of the memory portion of the cartridge 7 and the electrical contact unit of the main assembly 100 , at a plane parallel to the lengthwise direction of the process cartridge 7 , showing their states prior to , and after , the final step of the mounting of the cartridge 7 into the apparatus main assembly 100 . referring to fig6 ( a ), the lengthwise direction of the drum , which is the same as the direction ( indicated by arrow mark x ) of the rotational axis of the photosensitive drum 1 , is referred to as the width direction of the memory substrate 202 . further , the direction ( indicated by arrow mark y ) in which the cartridge 7 is inserted into , or removed from , the apparatus main assembly 100 , that is , the direction perpendicular to the above described width direction of the memory substrate 202 , is referred to as the thickness direction of the memory substrate 202 . further , the direction ( indicated by arrow mark z ) perpendicular to the above described width and thickness directions of the memory substrate 202 is referred to as the height direction of the memory substrate 202 . the cleaner unit frame 51 is provided with a contact supporting means 204 for supporting the memory substrate 202 , and the memory supporting means 204 is provided with a recess 205 , which is for accommodating the memory 200 attached to one of the primary surfaces of the memory substrate 202 . the memory accommodating recess 205 is located roughly in the center of the contact supporting means 204 . in the adjacencies of the memory accommodating recess 205 , a surface 206 is provided , which is for taking the pressure that bears on the memory substrate 202 as the electrical contacts 201 a and 201 b of the cartridge 7 are placed in contact with the electrical contacts 104 a and 104 b , respectively , in order to regulate the movement of the memory substrate 202 in the thickness direction , which might be caused by the abovementioned pressure . further , there are a pair of regulating members 220 a and 220 b on the outward side of the pressure taking surface 206 in terms of the lengthwise direction of the photosensitive drum 1 . the regulating members 220 a and 220 b are l - shaped in cross section , and are integral parts of the cleaner unit frame 51 ( fig8 : sectional view ). with the provision of the above described portions and members , a pair of slits 207 a and 207 b are effected , which sandwich the pressure taking surface 206 . these slits 207 a and 207 b constitute the contact supporting means in this embodiment . the slits 207 a and 207 b have openings 211 a and 211 b , respectively , which are on the top side of the slits 207 a and 207 b in terms of the height direction of the memory substrate 202 . as for the method for attaching the memory substrate 202 to the cartridge 7 , the edge portions 202 a and 202 b of the memory substrate 202 , which are on the opposite sides of the combination of the electrical contacts 201 a and 201 b of the cartridge 7 , are to be engaged into the slits 207 a and 207 b , through the openings 211 a and 211 b of the slits 207 a and 207 b , respectively . in this embodiment , the memory substrate 202 is rectangular . however , the design of the structure for engaging the memory substrate 202 into the slits 207 a and 207 b is not limited by the shape of the memory substrate 202 . that is , all that is necessary is that the edge portions 202 a and 202 b of the memory substrate 202 , which are on the opposite sides of the combination of the electrical contacts 201 a and 201 b of the cartridge 7 , can be engaged one for one into the pair of slits 207 a and 207 b of the cleaner unit frame 51 . as the memory substrate 202 is inserted into the slits 207 a and 207 b as described above , the movement of the memory substrate 202 in the width direction is regulated by a first regulating portion , which has a preset amount of gap , whereas the movement of the memory substrate 202 in the thickness direction is a second regulating portion , which has a preset amount of gap . more specifically , the first regulating portion is made up of a pair of surfaces opposing each other , with the presence of the preset amount of gap , in terms of the width direction of the memory substrate 202 , that is , the inwardly facing surface of the regulating member 220 a and the inwardly facing surface of the regulating member 220 b , in terms of the width direction of the memory substrate 202 . the second regulating portion is made up of the pressure taking surface 206 , the surface of the regulating member 220 a , which opposes the pressure taking surface 206 , with the presence of the preset amount of gap , in terms of the thickness direction of the memory substrate 202 , and the surface of the regulating member 220 b , which opposes the pressure taking surface 206 , with the presence of the preset amount of gap , in terms of the thickness direction of the memory substrate . with the provision of the above described structural arrangement , as the memory substrate 202 is inserted into the slits 207 a and 207 b , the movement of the memory substrate 202 in the width direction of the memory substrate 202 is regulated by the inwardly facing surface of the regulating member 220 a and the inwardly facing surface of the regulating member 220 b , which face each other in terms of the width direction of the memory substrate 202 , whereas the movement of the memory substrate 202 in the thickness direction of the memory substrate 202 is regulated by the pressure taking surface 206 , and the surface of the regulating member 220 a , which opposes the pressure taking surface 206 , with the presence of the preset amount of gap , in terms of the thickness direction of the memory substrate 202 , and the surface of the regulating member 220 b , which opposes the pressure taking surface 206 , with the presence of the preset amount of gap , in terms of the thickness direction of the memory substrate . here , the gap of the second regulating portion , that is , the distance w 1 between the pressure taking surface 206 , and the surface of the regulating member 220 a ( 220 b ) which opposes the pressure taking surface 206 in terms of the thickness direction of the memory substrate 202 , is rendered slightly greater than the dimension w 2 of the memory substrate 202 in terms of the thickness direction of the memory substrate 202 ( w 1 & gt ; w 2 ). the gap of the first regulating portion , that is , the distance w 5 between the inward surfaces of the regulating members 220 a and 220 b , which oppose each other in terms of the width direction of the memory substrate 202 , is rendered slight greater than the dimension w 6 of the memory substrate 202 in terms of the width direction of the memory substrate 202 . therefore , the memory substrate 202 can be easily ( without substantial amount of physical resistance ) inserted into the slits 207 a and 207 b . as for the relationship between the gap w 1 of the second regulating portion and the thickness w 2 of the memory substrate 202 , it is such that satisfies the following inequities : w 2 & lt ; w 1 , and ( w 1 − w 2 )& lt ; u . here , “ u ” represents the amount of stroke of the electrical contact 104 a ( 104 b ). that is , the amount of play that the memory substrate 202 is afforded in terms of the thickness direction y of the memory substrate 202 is no less than zero , ensuring that the memory substrate 202 comes into contact with the pressure taking surface 206 , within the range of the stroke of the electrical contacts 104 a and 104 b of the apparatus main assembly 100 . the position of the pressure taking surface 206 is set so that the gap w 1 of the second regulating portion , that is , the distance between the pressure taking surface 206 , and the surface of the regulating member 220 a ( 220 b ), which opposes the pressure taking surface 206 , can ensure that as the memory substrate 202 is inserted into the slits 207 a and 207 b , electrical connection is established between the electrical contacts 201 a and 201 b of the cartridge 7 and the electrical contacts 104 a and 104 b of the apparatus main assembly 100 by the contact pressure generated as the memory substrate 202 comes into contact with the pressure taking surface 206 . the gap between the abovementioned pair of regulating members 220 a and 220 b constitutes the gap through which the electrical contacts 201 a and 201 b of the cartridge 7 remain unobstructedly exposed after the memory substrate 202 is properly inserted into the slits 207 a and 207 b . in terms of the width direction of the memory substrate 202 , the dimension w 3 of the exposure gap is set so that it is greater than dimension w 4 of the combination of the electrical contacts 201 a and 201 b of the cartridge 7 on the memory substrate 202 . here , the relationship among the dimensions w 3 , w 4 , w 5 , and w 6 is : w 3 & gt ; w 4 ; w 5 & gt ; w 6 ; and ( w 3 − w 4 )& gt ;( w 5 − w 6 ). in other words , the play , in the width direction x of the memory substrate 202 , afforded for the memory substrate 202 is set so that it is no less than zero , and also , so that even if the memory substrate 202 displaces in its width direction x , the electrical contacts 201 a and 202 b of the cartridge 7 are not covered by the regulating members 220 a and 220 b , respectively . further , there are a pair of projections 208 a and 208 b , which are located next to the abovementioned openings 211 a and 211 b of the slits 207 a and 207 b , respectively ; in other words , the projections 208 a and 208 b are located next to the top portions of the slits 207 a and 207 b , respectively . when attaching the memory substrate 202 to the cleaner unit frame 51 , the memory substrate 202 is to be inserted from the direction indicated by an arrow mark p in fig6 ( a ) until the memory substrate 202 strikes the top surface of a projection 209 ( fig6 ( b )) located at the bottom end of each of the slits 207 a and 207 b . thereafter , the abovementioned projections 208 a and 208 b located next to the top ends of the slits 207 a and 207 b are to be melted by the direct application of heat , application of ultrasonic waves , or the like method , from the direction p , so that the openings of the slits 207 a and 207 b are covered ( fig6 ( c )). in other words , the projections 208 a and 208 b are turned into a pair of memory substrate retaining portions 210 a and 210 b for preventing the memory substrate 202 from slipping out of the slits 207 a and 208 a . thus , once the memory substrate 202 is attached to the cleaner unit frame 51 using the above described structural arrangement and method , it will not disengage from the cleaner unit frame 51 . incidentally , in this embodiment , the memory substrate 202 is prevented from disengaging from the cartridge 7 , by melding the projections 208 a and 208 b . however , the method for preventing the disengagement of the memory substrate 202 does not need to be limited to the above described method . for example , the downstream end portion of each of the slits 207 a and 207 b , in terms of the direction in which the memory substrate 202 is inserted , may be provided with such a projection that renders the dimension of the corresponding portion of each of the slits 207 a and 207 b , in terms of the width direction of the memory substrate 202 , slightly less than the width of the memory substrate 202 . in the case of this design , a small amount of pressure has to be applied to the memory substrate 202 to insert the memory substrate 202 into the slits 207 a and 207 b . however , this design requires no other step to be taken after the insertion of the memory substrate 202 ; the memory substrate 202 is prevented by the projections from coming out of the slits 207 a and 207 b . in this embodiment , after the attachment of the memory substrate 202 to the cleaner unit frame 51 , the electrical contacts 201 a and 201 b of the cartridge 7 are between the edge portions 202 a and 202 b of the memory substrate 202 , which are inserted 207 a and 207 b . therefore , the electrical contacts 201 a and 201 b of the cartridge 7 are recessed from the surface of the cleaner unit frame 51 , which surrounds electrical contacts 201 a and 201 b . therefore , a user is prevented from touching the electrical contacts 201 a and 201 b of the cartridge 7 when the user is handling the cartridge 7 . next , the removal of the memory substrate 202 , which occurs when recycling the cartridge 7 , will be described . the method for removing the memory substrate 202 from the cartridge 7 is as follows : first , the memory substrate retaining portions 210 a and 210 b created by melting the projections 208 a and 208 b are to be cut away with the use of such a tool as a nipper , to expose the openings 211 a and 211 b of the slits 207 a and 207 b , respectively . with the openings 211 a and 211 b exposed , the memory substrate 202 can be easily removed . as for the method for attaching a brand - new substrate 202 to a recycled cartridge 7 , first , the brand - new substrate 202 is to be inserted into the slits 207 a and 207 b . then , the slits 207 a and 207 b are to be directly welded shut , or are shut by welding additional members to the top ends of the slits 207 a and 207 b , to prevent the memory substrate 202 from slipping out of the slits 207 a and 207 b . with the employment of the above described recycling method , the cartridge 7 can be repeatedly recycled . [ structure for keeping connected electrical contacts of cartridge and electrical contact of apparatus main assembly ] next , referring to fig7 , the structure for connecting and keeping connected the electrical contacts 201 a and 201 b of the memory 200 of the cartridge and the electrical contacts 104 a and 104 b of the apparatus main assembly 100 will be described . as described above , the cartridge 7 is provided with the memory substrate 202 , which is attached to the cleaner unit frame 51 , which is on the back side of the cartridge 7 . the main assembly 100 is also provided with a contact supporting portion 105 for supporting the electrical contacts 104 a and 104 b of the apparatus main assembly 100 , and a supporting member 106 for supporting the contact supporting portions 105 . the contact supporting portion 105 and contact supporting portion supporting member 106 are integral parts of a contact unit 108 , which is attached to a main assembly frame 109 , being enabled to move only in the length direction of the drum ( width direction of memory circuit board ). the cartridge 7 is to be inserted rear side first ( fig4 ) into the cartridge bay of the apparatus main assembly 100 ( fig4 ). as described above , the cartridge 7 is provided with the contact positioning groove 203 as the cartridge positioning portion on the cartridge 7 side . further , the abovementioned supporting member 106 of the apparatus main assembly 100 is provided with a positioning boss 107 also as a cartridge positioning member . thus , as the cartridge 7 is inserted into the apparatus main assembly 100 , the contact positioning grooves 203 of the cartridge 7 engage with the positioning bosses 107 of the supporting member 106 , before the cartridge 7 reaches a preset position in the apparatus main assembly 100 . as a result , the contact unit 108 is accurately positioned relative to the cartridge 7 . thereafter , the electrical contacts 201 a and 201 b of the cartridge , with which the memory substrate 202 is provided , come into contact with the electrical contacts 104 a and 104 b of the apparatus main assembly 100 , establishing thereby electrical contact between the cartridge 7 and apparatus main assembly 100 . consequently , it becomes possible for electrical information to be exchanged between the memory 200 and the control circuit portion ( unshown ) of the apparatus main assembly 100 . incidentally , for the reliability in electrical connection , the electrical contacts 201 a and 201 b of the cartridge 7 , and the electrical contacts 104 a and 104 b of the apparatus main assembly 100 , are plated with gold . more specifically , in this embodiment , the electrical contacts 104 a and 104 b of the apparatus main assembly 100 , and the electrical contacts 201 a and 201 b of the cartridge 7 , are formed of copper , and are plated with gold . regarding the engagement between the positioning boss 107 and contact positioning groove 203 , it does not need to be perfect . that is , it may be loose enough for the cartridge 7 to be easily inserted , as long as it is not too loose for accurate positioning of the cartridge 7 . it should be noted here that in terms of the height direction z of the memory substrate 202 , the engagement between the positioning boss 107 and contact positioning groove 203 does not fix the positional relationship between the cartridge 7 and apparatus main assembly 100 ; in other words , the cartridge 7 is allowed to move in the height direction z of the memory substrate 202 even after the engagement between the positioning bosses 107 and contact positioning grooves 203 . in other words , in terms of the height direction ( indicated by arrow mark z in fig6 ( a )), the contact unit 108 and cartridge 7 are separately positioned relative to the frame 109 of the apparatus main assembly 100 . at this time , referring to fig8 , the steps in the process for mounting the cartridge 7 into the apparatus main assembly 100 will be described as seen from an angle different from the angle from which they were seen in fig6 and 7 . as a user moves the cartridge 7 in the cartridge insertion direction ( indicated by arrow mark q in fig8 ( a )), the tip portion of the positioning boss 107 enters the contact positioning groove 203 of the cleaner unit frame 51 ( fig8 ( b )). then , as the cartridge 7 is further inserted , the positioning boss 107 fully engages with the contact positioning groove 203 , and thereafter , the electrical contacts 201 a and 201 b of the cartridge 7 come into contact with the electrical contacts 104 a and 104 b of the apparatus main assembly 100 , respectively . the tip portion of the positioning boss 107 is tapered to ensure that the positioning boss 107 is guided into the contact positioning groove 203 , even if the cartridge 7 is deviated in position in terms of the lengthwise direction of the photosensitive drum 1 while it is mounted into the apparatus main assembly 100 . with the employment of the above described structural arrangement , it is ensured that as the cartridge 7 is mounted into the apparatus main assembly 100 , the axial line of the positioning boss 107 falls within the contact positioning groove 203 . therefore , even if a certain amount of play is present , as described above , between the memory substrate 202 and the walls of the memory substrate slot of the apparatus main assembly 100 , in terms of the lengthwise direction of the photosensitive drum 1 , the contact unit 103 is accurately positioned relative to the memory substrate 202 , in terms of the lengthwise direction of the photosensitive drum 1 , directly by the positioning boss 107 and contact positioning groove 203 , in the immediate adjacencies of the memory substrate 202 . therefore , it is assured that electrical connection is established between the electrical contacts 104 a and 104 b of the apparatus main assembly 100 and the electrical contacts 201 a and 201 b of the cartridge 7 , respectively . next , referring to fig9 , the positioning of the memory substrate 202 in terms of its thickness direction will be described . as described above , a certain amount of play is provided between the memory substrate 202 and the walls of the slits 207 ( 207 a and 207 b ). therefore , in terms of the thickness direction of the memory substrate 202 , the memory substrate 202 may be in any place in the slits 207 . the electrical contacts 104 ( 104 a and 104 b ) of the apparatus main assembly 100 are formed of an elastic substance , and are in the form of a spring , projecting from the contact supporting portion 105 ( indicated by solid line in fig9 ). thus , as the cartridge 7 is inserted to a preset point in the apparatus main assembly 100 , the electrical contacts 104 of the apparatus main assembly 100 are pressed into the contact supporting portion 105 as shown by the broken line in fig9 . in other words , the contact points of the electrical contacts 104 of the apparatus main assembly 100 are allowed to move a preset distance in the cartridge insertion direction . therefore , as the cartridge 7 is mounted into the apparatus main assembly 100 , the electrical contacts 104 of the apparatus main assembly 100 and the electrical contacts 201 ( 201 a and 201 b ) of the cartridge 7 come into contact with each other , and then , are kept pressed against each other . that is , the electrical contacts 104 of the apparatus main assembly 100 flex a preset amount . as a result , the memory substrate 202 is pressed upon the pressure taking surface 206 of the cartridge 7 by the resiliency of the electrical contacts 104 of the apparatus main assembly 100 ( electrical contacts 104 change in shape from the one drawn with broken line to the one drawn by solid line ). consequently , the memory substrate 202 becomes fixed in terms of its position in the slits 207 , and also , the electrical contacts 104 of the apparatus main assembly 100 and the electrical contacts 201 of the cartridge 7 are kept pressed upon each other , ensuring that the electrical connection is maintained between the cartridge 7 and apparatus main assembly 100 . further , as the electrical contacts 104 of the apparatus main assembly 100 come into contact with the electrical contacts of the cartridge 7 , the points of contact of the electrical contacts 104 of the apparatus main assembly 100 move relative to the electrical contacts 201 of the cartridge 7 , causing thereby the electrical contacts 104 of the apparatus main assembly and the electrical contacts 201 of the cartridge 7 to wipe each other . therefore , even if dust or the like adheres to the electrical contacts , it is removed by the wiping , ensuing that the electrical contacts 104 and electrical contact 201 are placed , and remain , perfectly in contact with each other . here , as the wiping occurs , the electrical contacts 201 of the cartridge 7 and electrical contacts 104 of the apparatus main assembly 100 rub against each other . however , the number of opportunities for the electrical contacts 201 and electrical contacts 104 to rub against each other equals the number of times the cartridge 7 is replaced . further , the number of times the cartridge 7 is replaced is very small compared to the total number of copies made during the life of apparatus main assembly 100 . therefore , it does not occur that the electrical contacts 104 of the apparatus main assembly 100 are shaved through the normal replacement of the cartridge 7 ; they are simply wiped . after the proper mounting of the cartridge 7 into the apparatus main assembly 100 , the supporting member 105 is integrally held to the cleaner unit 50 in terms of the lengthwise direction of the photosensitive drum 1 . thus , if the cartridge 7 shifts in its lengthwise direction in the apparatus main assembly 100 , the supporting member 106 moves with the cleaner unit frame 51 . referring to fig7 , the electrical contacts 104 of the apparatus main assembly 100 are in the form of a leaf spring . therefore , if the electrical contacts 104 are subjected to such force that acts in the lengthwise direction of the photosensitive drum 1 , it is possible that the electrical contacts 104 will break . however , the supporting member 106 in this embodiment moves with the cleaner unit frame 51 . therefore , the electrical contacts 104 a and 104 b of the apparatus main assembly 100 and the electrical contacts 201 a and 201 b of the cartridge 7 are prevented from rubbing against each other . as described above , the cartridge 7 in this embodiment is provided with the pair of slits , which are open at one end ; the cleaner unit frame 51 of the cartridge 7 is provided with the pair of slits . the memory substrate 202 is held to the cartridge 7 ( cleaning frame 51 ), by inserting the memory substrate 202 into the pair of slits so that the pair of opposing edge portions of the memory substrate 202 , between which the electrical contacts 201 a and 201 b are located , are inserted into the pair of slits , one for one . in other words , the memory substrate 202 can be attached to the cartridge 7 with the use of a very simple method . further , as the contact supporting member is inserted through the contact supporting member through its opening , the movement of the contact supporting member is regulated by the first and second regulating portions , making it also very simply to attach the contact supporting member . further , the electrical contacts 201 a and 201 b of the memory substrate 202 , or the electrical contacts on the cartridge side , are disposed on the area which is recessed from the portion of the cartridge frame surface , which surrounds the area . therefore , the electrical contacts 201 a and 201 b are not likely to be touched by user &# 39 ; s fingers or the like , eliminating one of the causes of the failure in electrical connection . further , the gap of each slit , in which the memory substrate 202 is inserted , is rendered slightly greater than the thickness of the memory substrate 202 , and the positioning of the memory substrate 202 in terms of the thickness direction of the memory substrate 202 is accomplished by the resiliency of the electrical contacts 104 a and 104 b of the apparatus main assembly 100 , which are in the form of a leaf spring . therefore , the memory substrate 202 can be easily inserted into the slits 207 a and 207 b , improving the cartridge 7 in assembly efficiency . further , in terms of the width direction of the memory substrate 202 , such an amount of play that does not allow the regulating members 220 a and 220 b for supporting the memory substrate 202 , to cover the electrical contacts 201 a and 201 b of the cartridge 7 is provided between the memory substrate 202 and regulating members 201 a and 201 b , improving thereby the memory substrate 202 in assembly efficiency . further , after the insertion of the memory substrate 202 into the slits 207 a and 207 b , the opening portions of the slits 207 a and 207 b can be filled in to prevent the memory substrate 202 from slipping out of the slits 207 a and 207 b . that is , the memory substrate 202 can be attached to the cartridge 7 with the use of a simple method . further , the direction in which the memory substrate 202 is inserted into the slits 207 a and 207 b is the same as the direction ( in this embodiment , from top side of slits ) from which the opening portions of the slits are filled , improving thereby the assembly efficiency . further , regarding the recycling of the cartridge 7 , the memory substrate 202 can be easily removed by cutting off the retainer portions , that is , the portions filling the top ends of the slits 207 a and 207 b , and the memory substrate 202 can be firmly fixed to the cartridge 7 by refilling the openings created by the cutting of the retainer portions . in other words , this embodiment makes it possible to recycle the cartridge 7 through a simple process , improving the cartridge 7 in terms of recycle efficiency . further , in this embodiment , the memory substrate 202 is attached to the cartridge 7 by being inserted into the slits 207 a and 207 b . the electrical contacts 201 a and 201 b of the cartridge 7 are placed on one of the primary surfaces of the memory substrate 202 , whereas the memory 200 is placed on the other primary surface . therefore , not only is this embodiment effective to reduce the memory substrate 202 in size , but also , it makes it possible to easily attach to the cartridge 7 even a substrate ( 202 ), the primary surfaces of which have protrusions , being therefore not flat enough for two - sided adhesive tape , adhesive , or the like , to be properly applied . further , it is in the adjacencies of the memory substrate 202 that the unit which supports the electrical contacts 104 a and 104 b of the apparatus main assembly 100 is accurately positioned directly relative to the cartridge frame in terms of at least the lengthwise direction of the photosensitive drum 1 . therefore , the memory substrate 202 can be increased in the play relative to the walls of the slits 207 a and 207 b , to further improve the cartridge 7 in assembly efficiency . further , the memory substrate 202 is designed so that the opposing two edge portions of the memory substrate 202 are to be inserted into the slits one for one , and also , so that the electrical contacts 201 a and 201 b of the cartridge 7 are placed on the portions of the memory substrate 202 , which are not the portions to be inserted into the slits . therefore , the electrical contacts can be reduced in contact area to reduce the electrical contacts in the amount of gold , that is , a highly costly substance , used for plating them . next , referring to fig1 , the second embodiment of the present invention will be described . incidentally , the apparatuses in this embodiment are the same in basic structure as those in the above described first embodiment . therefore , they will be not be described to avoid the repetition of the same descriptions ; only the structural arrangements that characterize this embodiment will be described . the components , portions , etc ., which are the same in function as those in the first embodiment will be given the same referential symbols as those given in the first embodiment . in the above described first embodiment , the electrical contacts 201 a and 201 b , or the electrical contacts on the cartridge side , and the memory 200 are integrally attached to the memory substrate 202 . in this embodiment , however , the memory substrate holds only the memory . that is , the electrical contacts on the cartridge side are not integral parts of the memory substrate 202 . incidentally , fig1 does not show the memory substrate in this embodiment , that is , the substrate which holds only the memory . in this embodiment , the memory which stores the cartridge information is attached to a preset portion of the cartridge 7 . the electrical contacts 301 a and 301 b of the cartridge 7 are attached to a substrate 302 , from which the memory is physically independent . the electrical contacts 301 a and 301 b are electrically connected to the memory by unshown wiring . the structure for attaching the substrate 302 to the cartridge 7 is the same as the above described one in the first embodiment . by rendering the memory physically independent from the electrical contacts of the cartridge , more latitude can be afforded in the positioning of the memory and the electrical contacts therefor in the cartridge 7 , improving thereby the cartridge 7 in spatial efficiency . the preceding embodiments were described with reference to the electrophotographic color image forming apparatus employing a developing method of the contact type , and the cartridge therefor . however , the present invention is also applicable to an electrophotographic monochromatic image forming apparatus , an electrophotographic image forming apparatus of the noncontact type , a development unit mountable in the apparatus main assembly , and a developer unit which is mountable in the apparatus main assembly and stores developer . in the preceding embodiments , the definition of a process cartridge was a cartridge which has a photosensitive drum and at least one processing means . as examples of the processing means , there are a charging means , a developing means , and a cleaning means . thus , the process cartridge means : a cartridge in which a charging means , a developing means or a cleaning means , and a photosensitive drum , are integrally disposed , and which is removably mountable in the main assembly of an image forming apparatus ; a cartridge in which at least one among a charging means , a developing means , and cleaning means , and a photosensitive drum , are integrally disposed , and which is removably mountable in the main assembly of an image forming apparatus ; and a cartridge in which at least a developing means and a photosensitive drum are integrally disposed , and which is removably mountable in the main assembly of an image forming apparatus . further , an electrophotographic image forming apparatus means an apparatus which forms an image on recording medium with the use of an electrophotographic image forming method . as examples of an electrophotographic image forming apparatus , an electrophotographic copying machine , an electrophotographic printer ( for example , laser beam printer , led printer , and the like ), a facsimileing apparatus , a wordprocessor , etc ., can be included . 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 purposes of the improvements or the scope of the following claims . this application claims priority from japanese patent application no . 113398 / 2005 filed apr . 11 , 2005 which is hereby incorporated by reference .