hereinafter , a detailed description of the preferred embodiments of the present invention will be given with reference to the accompanying figures . fig1 is a block diagram for showing a configuration of an embodiment of the image forming system according to the present invention . in fig1 , the image forming system is configured of a paper feed device 101 , an image forming device ( printer ) 102 , and a paper discharge device 103 . the paper feed device 101 is provided with a lower deck 104 , an upper deck 105 , paper feed rollers 108 and 109 for feeding paper sheets stacked on each deck . furthermore , the paper feed device 101 is provided with a conveyor roller 110 for conveying the paper sheets fed from each deck into the image forming device 102 , and a paper outlet sensor 111 provided in the downstream of the conveyor roller 110 . the image forming device 102 is provided with a lower deck 106 , an upper deck 107 , paper feed rollers 112 and 113 , and a paper feeding sensor 114 for detecting a paper sheet supplied from the paper feed device 101 and from the lower deck 106 or the upper deck 107 . in addition , the image forming device 102 is provided with a paper feed and convey roller 115 for further conveying the supplied paper sheet . moreover , the image forming device 102 is provided with a resist roller 117 for feeding the paper sheet until a predetermined loop is formed , and a paper sensor ( hereinafter referred to as “ pre - resist sensor ”) 116 for detecting the front edge of the paper sheet conveyed in order to form the loop . besides , the image forming device 102 is provided with a photosensitive drum 118 , a fixing device 119 , a paper exit roller 120 , and a paper exit roller sensor 121 that is located at the most downstream in the paper conveyance path of the image forming device 102 for monitoring a paper conveying state . the timing of starting rotation of the resist roller 117 is determined based on the timing when a front edge of the paper sheet is detected by the pre - resist sensor 116 . in addition , in order to accurately transfer an image formed on the photosensitive drum 118 onto the paper sheet , timing for starting rotation of the resist roller 117 is controlled . for a predetermined period , since the pre - resist sensor 116 detects the front edge of the paper sheet , a state where the resist roller 117 is not driven is maintained , and the paper sheet is conveyed at a predetermined length in order to form the loop of paper . after the predetermined time , the resist roller 117 is rotatively driven to convey the paper sheet , and thereby the image on the photosensitive drum 118 is transferred onto the paper sheet . after that , the paper sheet on which the image has been transferred is discharged from the image forming device 102 to the paper discharge device 103 through the fixing device 119 and the paper exit roller 120 . the paper discharge device 103 detects the paper discharged from the image forming device 102 with an inlet sensor 122 , takes in and conveys the paper sheet with a conveyor roller 123 , and discharges it to any of designated paper discharging bins 124 . fig2 is a block diagram for showing a configuration of the image forming device 102 , or the like according to the present invention . in fig2 , reference numeral 201 is a video controller cpu mounted on a video controller for controlling the image forming device 102 , which carries out processing of image data and commands which are transmitted from a host computer . reference numeral 202 is a paper feed device control cpu for controlling the paper feed device 101 . reference numeral 203 is an image forming engine cpu for controlling an image forming engine ( printer engine ). reference numeral 204 is a paper discharge device control cpu for controlling the paper discharge device 103 . each cpu controls the respective devices in communicating interactively each other . reference numeral 205 is a sensor input circuit that enters a detection signal of the outlet sensor 111 in the paper feed device 101 into the paper feed device control cpu 202 . reference numeral 206 is a driving circuit of a motor 216 for rotating the paper feed rollers 108 and 109 , and the conveyor roller 110 of the paper feed device 101 , which is controlled by a driving signal outputted from the paper feed device control cup 202 . the paper feed device control cpu 202 feeds or conveys paper sheets from a desired deck in accordance with a paper feeding instruction or a conveyance instruction transmitted from the video controller cpu 201 . reference numerals 207 , 208 , and 209 are input circuits of , respectively , the paper feeding sensor 114 , the pre - resist sensor 116 , and the paper exit roller sensor 121 positioned on the conveyance path in the image forming device 102 . these input circuits enter the detecting signal into the image forming engine cpu 203 . reference numeral 210 is a driving circuit of a main motor 220 for driving all the rollers and photosensitive rollers in the image forming device 102 , which is controlled by the driving signal outputted from the image forming engine cpu 203 . reference numeral 211 is a driving circuit of a clutch 221 for transferring the rotation of the main motor 220 to the paper feed - convey roller 115 , which is controlled by the driving signal outputted from the image forming engine cpu 203 . reference numeral 212 is a driving circuit of a clutch 222 for transferring the rotation of the main motor 220 to the resist roller 117 . the driving circuit 212 allows the clutch 222 to turn on / off by the driving signal outputted from the image forming engine cpu 203 . reference numeral 215 is a driving circuit of a clutch 223 for transferring the rotation of the main motor 220 to the fixing device 119 . reference numeral 217 is a driving circuit of a clutch 225 for transferring the rotation of the main motor 220 . the driving circuits 215 and 217 allow the clutches to turn on / off by the driving signal outputted from the image forming engine cpu 203 . turning on / off the driving system for paper supplying and conveying sides in the image forming device 102 ( the paper feed rollers 112 and 113 , the paper feed - convey roller 115 , and the photosensitive drum 118 ) and turning on / off the driving system for paper discharging ( the fixing device 119 and the paper exit roller 120 ) are independently controlled . the image forming engine cpu 203 conveys the paper sheet to the paper discharge device 103 corresponding to a conveyance instruction transmitted from the video controller cpu 201 . reference numeral 213 is a sensor input circuit that enters a detecting signal of the inlet sensor 122 in the paper discharge device 103 into the paper discharge device control cpu 204 . reference numeral 214 is a driving circuit of a motor 224 for rotating the conveyor roller 123 of the paper discharge device 103 , which is controlled by a driving signal outputted from the paper discharge device control cpu 204 . the paper discharge device control cpu 204 conveys the paper sheet from the image forming device 102 by a conveyance instruction transmitted from the video controller cpu 201 . fig3 is a sequential diagram for showing an example of a first processing at a time when poor paper feeding ( such as paper jam ) is caused in the paper feed device 101 . this sequential diagram shows control information and a command ( an instruction signals ) transmitted / received between the video controller cpu 201 and the paper feed device control cpu 202 . additionally , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cup 201 and the image forming engine cpu 203 . moreover , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the paper discharge device control cpu 204 . furthermore , this sequential diagram shows a flow of controlling the video controller cpu 201 , the paper feed device control cpu 202 , the image forming engine cpu 203 , and the paper discharge device control cpu 204 . when a paper jam is caused in the paper feed device 101 ( step 301 ), the paper feed device control cpu 202 detects the paper jam at step 302 . next , the paper feed device control cpu 202 stops conveyance in the paper feed device 101 , and transmits to the video controller cpu 201 conveyance stop state information showing that the conveyance on a paper discharging side in the paper feed device 101 is stopped . at steps 303 and 304 , the video controller cpu 201 which has received the conveyance stop state information transmits a selective conveyance stop instruction to both the image forming device 102 such as a printer and the paper discharge device 103 . the image forming device 102 and the paper discharge device 103 , which have received the selective conveyance stop instruction , determine per se whether to continue or to immediately stop the conveyance , based on whether or not there is sheets of paper capable of being conveyed . in the present processing example , as described later , the image forming device 102 stops paper conveyance immediately and the paper feed device 103 continues paper conveyance . at step 305 , the image forming device 102 , which has received the selective conveyance stop instruction , transmits to the video controller cpu 201 conveyance stop information showing that the paper conveyance on a paper supplying side is stopped . then , at step 306 , the image forming device 102 stops to convey the sheets of paper , on the paper supplying side in the image forming device 102 , whereas continues to convey the sheets of paper on the paper discharging side . that is , at step 308 , the image forming device 102 stops conveying the sheets of paper after the image forming device 102 finishes discharging to the paper discharge device 103 all the sheets of paper which exist and are capable of being conveyed in the image forming device 102 . then , at step 309 , the image forming device 102 transmits the conveyance stop state information to the video controller cpu 201 . at step 310 , the video controller cpu 201 , which has received the conveyance stop state information , transmits to the paper discharge device 103 a selective conveyance stop instruction showing that the operation of the paper conveyance on the paper supplying side in the image forming device 102 is stopped . at step 311 , the paper discharge device 103 continues to convey the sheets of paper even after receiving the selective conveyance stop instruction . at step 312 , the paper discharge device 103 stops conveying the sheets of paper after all the sheets of paper which exist and are capable of being conveyed in the paper discharge device 103 are completely discharged . next , the paper discharge device 103 transmits to the video controller cpu 201 the conveyance stop state information showing that the paper conveyance is stopped . the video controller cpu 201 releases the state of the selective conveyance stop upon receipt of the conveyance stop state information showing that the paper conveyance is stopped from all the devices , which are the paper feed device 101 , the image forming device 102 , and the paper discharge device 103 . in order to release the state of the selective conveyance stop , at steps 314 , 315 , and 316 , the video controller cpu 201 transmits an instruction for releasing the selective conveyance stop to the image forming device 102 , the paper feed device 101 , and the paper discharge device 103 . lastly , at step 307 , an operator starts a normal process for the paper jam and each device returns to a normal sequence . as described above , according to the present processing example , in cases where a paper jam is caused in the paper feed device 101 and conveyable sheets of paper exist in the image forming device 102 , these sheets are discharged to the paper discharge device 103 . thereby , it becomes possible to reduce residual paper sheets which a user should remove . besides , when a paper jam is caused in the paper feed device 101 , the image forming device 102 and the paper discharge device 103 carry out the conveying operation by respectively determining whether or not to continue the conveying operation , based on the information transmitted from the video controller . therefore , the paper discharge device 103 is capable of effectively discharging the residual paper sheets in the device . fig4 is a sequential diagram for showing an example of a second processing at a time when poor sheet feeding is caused in the paper feed device 101 due to the paper jam or the like . this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the paper feed device control cpu 202 . furthermore , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the image forming engine cpu 203 . moreover , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the paper discharge device control cpu 204 . furthermore , this sequential diagram shows a flow of controlling the video controller cpu 201 , the paper feed device control cpu 202 , the image forming engine . cpu 203 , and the paper discharge device control cpu 204 . when a paper jam is caused in the paper feed device 101 ( step 401 ), the paper feed device control cpu 202 detects the paper jam at step 402 . next , the paper feed device control cpu 202 stops conveyance in the paper feed device 101 , and transmits to the video controller cpu 201 conveyance stop state information showing that the conveyance on the paper discharging side in the paper feed device 101 is stopped . at steps 403 and 404 , the video controller cpu 201 , which has received the conveyance stop state information , determines an operation of the image forming device 102 , and transmits to the image forming device 102 an instruction to stop the conveyance ( on the supplying side ) and an instruction to continue the conveyance ( on the discharging side ). at step 405 , the image forming device 102 , which has received the instruction to stop the conveyance ( on the supplying side ) and the instruction to continue the conveyance ( on the discharging side ), stops the paper conveyance on the supplying side , and continues the paper conveyance on the discharging side . that is , at step 406 , the image forming device 102 stops the paper conveyance in the image forming device 102 after sheets of paper , which exist and are capable of being conveyed in the image forming device 102 , are discharged to the paper discharge device 103 . next , at step 408 , the image forming device 102 transmits the conveyance stop state information to the video controller cpu 201 . at step 409 , the video controller cpu 201 , which has received the conveyance stop state information , transmits the instruction to continue the paper conveyance to the paper discharge device 103 . it should be noted that the paper discharge device 103 currently continues the paper conveyance at this time ( step 407 ). at step 410 , the paper discharge device 103 , which has received the instruction to continue conveyance , continues the paper conveyance . at step 411 , the paper discharge device 103 stops the paper conveyance after all sheets of paper , which exist and are capable of being conveyed in the paper discharge device 103 is completely discharged . at step 412 , the paper discharge device 103 transmits to the video controller cpu 201 the conveyance stop state information showing that the paper conveyance in the paper discharge device 103 is stopped . the video controller cpu 201 releases the conveyance continuing state upon receipt of the conveyance stop state information showing that the paper conveyance is stopped from all the devices of the paper feed device 101 , the image forming device 102 , and the paper discharge device 103 . in order to release the conveyance continuing state , at steps 413 , 414 , and 415 , the video controller cpu 201 transmits an instruction to release the conveyance continuing state to the image forming device 102 , the paper feed device 101 , and the paper discharge device 103 . lastly , at step 416 , an operator starts a normal process for a paper jam and each device returns to a normal sequence . as described above , according to the present processing example , in cases where a paper jam is caused in the paper feed device 101 and conveyable sheets of paper exist in the image forming device 102 , these sheets are discharged to the paper discharge device 103 . thereby , it becomes possible to reduce residual paper sheets which a user needs to remove . fig5 is a sequential diagram for showing an example of a third processing in cases where poor paper feeding ( such as a paper jam ) is caused in the paper feed device 101 due to the paper jam or the like . this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the paper feed device control cpu 202 . furthermore , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the image forming engine cpu 203 . moreover , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the paper discharge device control cpu 204 . furthermore , this sequential diagram shows a flow of controlling the video controller cpu 201 , the paper feed device control cpu 202 , the image forming engine cpu 203 , and the paper discharge device control cpu 204 . in this example of the present processing , information whether or not shared paper sheets are present is used . the shared paper sheets mean paper sheets that remain over the image forming device 102 and the paper feed device 101 , or over the image forming device 102 and the paper discharge device 103 . when a paper jam is caused in the paper feed device 101 ( step 301 ), at step 322 , the paper feed device control cpu 202 detects the paper jam and stops conveyance in the paper feed device 101 . next , the paper feed device control cpu 202 transmits to the video controller cpu 201 conveyance stopped state information showing that conveyance on a paper discharging side in the paper feed device 101 is stopped . the conveyance stopped state information also includes information showing whether or not a paper sheet is shared between the paper feed device 101 and the image forming device 102 , or between the image forming device 102 and the paper discharge device 103 . the information showing whether or not the paper sheet is shared can be obtained by monitoring states of the sensors 111 , 114 , 121 , and 122 shown in fig2 . for example , if the sensor 111 in the paper feed device 101 is turned on and the sensor 114 in the image forming device 102 is turned on , it is determined that the paper sheet is jammed over the paper feed device 101 and the image forming device 102 . in addition , if the sensor 121 in the image forming device 102 is turned on and the sensor 122 in the paper discharge device 103 is turned on , it is determined that the paper sheet is jammed over the image forming device 102 and the paper discharge device 103 . in this example of the present processing , a case where the paper sheet is not shared between the devices is shown . in this case , as described later , the image forming device 102 continues the conveyance on the supplying side . when a paper jam is caused in the paper feed device 101 ( step 301 ), at step 332 , the paper feed device control cpu 202 detects the paper jam , and stops the conveyance in the paper feed device 101 . next , the paper feed device control cpu 202 transmits to the video controller cpu 201 conveyance stopped state information showing that the conveyance on the paper discharging side in the paper feed device 101 is stopped and a shared paper sheet is absent . the video controller cpu 201 , which has received the conveyance stopped state information at step 332 , transmits a selective conveyance stop instruction to both the image forming device 102 such as a printer and the paper discharge device 103 . the image forming device 102 and the paper discharge device 103 , which have received the selective conveyance stop instruction , determine whether the conveyance is continued or the conveyance is immediately stopped . in the present processing example , the image forming device 102 received information showing “ a shared paper sheet is absent ” according to the selective conveyance stop instruction , and thereby , at step 336 , it continues the conveyance on the paper supplying side and the paper discharging side . on the other hand , the paper discharge device 103 also continues the conveyance . then , at step 308 , the image forming device 102 stops the conveyance after all the sheets of paper , which exist and are capable of being conveyed in the image forming device 102 , are completely discharged to the paper discharge device 103 . next , at step 339 , the image forming device 102 transmits to the video controller cpu 201 the conveyance stopped state information showing that conveyance in the image forming device 102 is stopped . the video controller cpu 201 , which has received the conveyance stopped state information , transmits a selective conveyance stop instruction to the paper discharge device 103 at step 340 . since a sheet of paper is not shared between the image forming device 102 and the paper discharge device 103 in the present processing example , the information showing that “ a shared paper sheet is absent ” is also transmitted to the paper discharge device 103 . the paper discharge device 103 , which has received the selective conveyance stop instruction , continues the conveyance at step 311 . the paper discharge device 103 stops the conveyance at step 312 after all the sheets of paper , which exist and are capable of being conveyed in the paper discharge device 103 , are completely discharged . subsequently , at step 343 , the paper discharge device 103 transmits to the video controller cpu 201 the conveyance stopped state information showing that the conveyance is stopped . the video controller cpu 201 releases the selective conveyance stopped state upon receipt of the conveyance stopped state information showing that the paper conveyance is stopped from all the devices of the paper feed device 101 , the image forming device 102 , and the paper discharge device 103 . in order to release the selective conveyance stopped state , at steps 314 , 315 , and 316 , the video controller cpu 201 transmits an instruction to release the selective conveyance stopped state to the image forming device 102 , the paper feed device 101 and the paper discharge device 103 . lastly , at step 317 , an operator starts a normal process for a paper jam and each device returns to a normal sequence . it should be noted that the following processing is carried out when a shared paper sheet is present . for example , when a paper jam is caused in the paper feed device 101 , the paper feed device control cpu 202 detects the paper jam , and stops conveyance in the paper feed device 101 . next , the paper feed device control cpu 202 transmits it to the video controller cpu 201 that paper conveyance on a paper discharging side in the paper feed device 101 is stopped . furthermore , the paper feed device control cpu 202 transmits to the video controller cpu 201 conveyance stopped state information showing that a sheet of paper is shared between the image information device 102 and the paper feed device 101 ( the sensors 111 and 114 are turned on ). upon receipt of the information , the video controller cpu 201 transmits the selective conveyance stop instruction together with information showing “ a shared paper sheet is present ” to the cpu 203 of the image forming device 102 and the cpu 204 of the paper discharge device 103 . the cpu 203 of the image forming device 102 stops driving operation on a supplying side and continues driving operation on a discharging side based on the selective conveyance stop instruction and the information showing that “ a shared paper sheet is present ”. in addition , the cpu 204 of the paper discharge device 103 continues the conveyance operation . since the subsequent operations are the same as those of the case when “ a shared paper sheet is absent ”, the description is omitted . in addition , when a paper jam is caused in the paper discharge device 103 , the paper discharge device control cpu 204 detects the paper jam , and stops conveyance in the paper discharge device 103 . next , the paper discharge device control cpu 204 transmits it to the video controller cpu 201 that the conveyance on paper supplying side in the paper discharge device 103 is stopped . furthermore , the paper discharge device control cpu 204 transmits to the video controller cpu 201 conveyance stopped state information showing that the paper sheet is shared between the image forming device 102 and the paper discharge device 103 ( the sensors 121 and 122 are turned on ). upon receipt of the information , the video controller cpu 201 transmits a selective conveyance stop instruction together with the information showing that “ a shared paper sheet is present ” to the cpu 203 of the image forming device 102 and the cpu 202 of the paper feed device 101 . upon receipt of the selective conveyance stop instruction and the information showing that “ a shared paper sheet is present ”, the cpu 203 of the image forming device 102 stops driving on the supplying side and discharging side . in addition , upon receipt of the selective conveyance stop instruction and the information showing that “ a shared paper sheet is present ”, the cpu 202 of the paper feed device 101 also stops conveyance operation . in other words , upon receipt of the information showing that “ a shared paper sheet is present ”, the cpu 203 and cpu 202 will carry out the following processing . the cpu 203 and cpu 202 control the devices in order to continue a part of the conveyance operation in cases where the paper sheet is shared between the image forming device 102 and the paper feed device 101 when the paper jam is caused in the paper feed device 101 . the cpu 203 and cpu 202 control the devices in order not to continue the conveyance operation in cases where the paper sheet is shared between the image forming device 102 and the paper discharge device 103 when the paper jam is caused in the paper discharge device 103 . according to the present processing example , the paper discharge device control cpu 204 also transmits the information whether or not a shared paper sheet , that is , a paper sheet remaining over the devices , is present . therefore , devices , located in the downstream of a device in which the poor paper feeding is caused , can accurately determine which part of conveyor rollers has to be stopped . thereby it becomes easy to discharge the paper sheets in conveying process in the devices without being damaged . it should be noted that the information showing that “ a sheared paper sheet is absent , or a shared paper sheet is present ”, which is described in the third processing example , can be applied to the sequence of the second processing example . fig6 is a sequential diagram for showing an example of a fourth processing in cases where poor paper feeding ( such as a paper jam ) is caused in the paper discharge device 103 due to a paper jam or the like . this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the paper feed device control cpu 202 . furthermore , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the image forming engine cpu 203 . moreover , this sequential diagram shows control information and a command ( an instruction signal ) transmitted / received between the video controller cpu 201 and the paper discharge device control cpu 204 . furthermore , this sequential diagram shows a flow of controlling the video controller cpu 201 , the paper feed device control cpu 202 , the image forming engine cpu 203 , and the paper discharge device control cpu 204 . in the present processing example , immediate stop request information is used . that is , the present processing example is configured so that it is possible to request the adjacently - connected devices to stop paper conveyance immediately . with this , in cases where damage to a conveyor motor , a conveyor roller or the like is to be expected to occur , and in cases where another poor paper feeding is expected to be further caused if the paper conveyance is continued , it becomes possible to immediately stop the paper conveyance in the adjacently - connected devices . when a paper jam is caused in the paper discharge device 103 ( step 431 ), at step 432 , the paper discharge device control cup 204 detects the paper jam , and stops paper conveyance in the paper discharge device 103 . then , the paper discharge device control cpu 204 transmits to the video roller cpu 201 conveyance stopped state information showing that the paper conveyance in the paper discharge device 103 is stopped . this conveyance stopped state information includes a request for immediate stop to the image forming device 102 . at step 433 , the video controller cpu 201 , which has received the conveyance stopped state information , transmits a selective conveyance stop instruction to the image forming device 102 . the image forming device 102 , which has received the selective conveyance stop instruction at step 433 , immediately stops the paper conveyance on the supplying side and the discharging side at steps 434 and 435 . subsequently , at step 436 , the image forming device 102 transmits to the video controller cpu 201 the conveyance stopped state information showing that conveyance on the supplying side and discharging side in the image forming device 102 is stopped . at step 437 , the video controller cpu 201 , which has received the conveyance stopped state information , transmits to the paper feed device 101 a selective conveyance stop instruction for instructing to immediately stop the paper feed device 101 . at step 438 , the paper feed device 101 , which has received the selective conveyance stop instruction , stops the paper conveyance . at step 439 , the paper feed device 101 , in which the paper conveyance is stopped , transmits the conveyance stopped state information to the video controller cpu 201 . the video controller cpu 201 , which has received the conveyance stopped state information , releases the selective conveyance stopped state upon receipt the state information of the conveyance stop from all the devices of the paper feed device 101 , the image forming device 102 , and the paper discharge device 103 . in order to release the selective conveyance stopped state , at steps 314 , 315 , and 316 , the video controller cpu 201 transmits the instruction to release the selective conveyance stopped state to the image forming device 102 , the paper feed device 101 , and the paper discharge device 103 . lastly , at step 317 , an operator starts a normal process for a paper jam and each device returns to a normal sequence . as described above , according to the present processing example , if it is needed to immediately stop the adjacent devices in cases where each device stops paper conveyance , the paper conveyance can be immediately stopped by utilizing the immediate stop request information . accordingly , it is possible to reduce damage to the devices due to unnecessary paper conveyance and to prevent an accordion paper jam with multiple folds , which is caused by conveying more paper sheets to a jammed one . it should be noted that the immediate stop request information described in the fourth processing example can be applied to the sequence of the second processing example . in the above described first to fourth processing examples , the driving force of the main motor 220 is transferred by using the clutches to the paper feed rollers 112 and 113 , the paper feed and convey roller 115 , the resist roller 117 , the photosensitive drum 118 , the fixing device 119 , and the paper exit roller 120 . the driving system motor on the paper supplying and conveying side in the image forming device 102 and the driving system motor on the paper discharging side in the image forming device 102 may be separately provided to control conveyance operations . it should be noted that the driving system on the paper supplying and conveying side in the image forming device 102 is the paper feed rollers 112 and 113 , the paper feed and convey roller 115 and the photosensitive drum 118 . the driving system on the paper discharging side in the image forming device 102 is the fixing device 119 and the fixing and discharging device 120 . in addition to these , there can be an embodiment in which a computer reads out programs programmed for the above described processing from a recording medium on which the programs are recorded , and executes the programs . the medium for recording the programs includes , for example , a flexible disk , a hard disk , an optical disk , a magneto - optical disk , a cd - rom , a cd - r , a magnetic tape , a nonvolatile memory card , and a rom . the present invention has been described in detail with respect to preferred embodiments , and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspect , and it is the intention , therefore , in the apparent claims to cover all such changes .