Patent Publication Number: US-7711302-B2

Title: Image forming apparatus

Description:
BACKGROUND 
   1. Field of the Invention 
   The present invention relates to an image forming apparatus which includes a function of cleaning a fusing section by passing a sheet on which an image is not formed, before resuming printing after relieving a jam, when a sheet is nipped in a fusing section at the time of an occurrence of the jam. 
   2. Description of Related Art 
   In an image forming apparatus such as a copier or a printer using electrophotography which transfers toner images on a sheet and heat-melts and fixes the transferred toner images fusing section cleaning methods have been proposed where, when a sheet may be nipped in a nip section of a fusing section when a jam occurs, a sheet on which an image has not been formed is passed through the fusing section after the jam is settled and before resuming printing, and toner adhered on a surface of the fusing section is transferred to the passed sheet so that the residual toner is removed. 
   For example, a technique is proposed such as when a printing operation is interrupted by a jam occurrence, etc., if a sheet may be nipped in a nip section of the fusing section at the time, a sheet with a same sheet size or larger and a smaller basis weight than the sheet used in the interrupted printing is chosen from the sheet storing section, and is fed through a fusing roller and pressure roller without forming an image after jam processing, so that residual adhered toner on the rollers are transferred and adhered to the passed sheet and the sheet is ejected to a sheet ejection tray different from the tray where the printed sheet is ejected (For example Japanese Patent Application Laid-open Publication No. 2006-154192, hereinafter referred to as Patent Document 1). 
   However, with the method of Patent Document 1, sheets which meet the above mentioned size condition and basis weight condition are automatically fed and passed from the sheet storing section. As a result, when size condition and basis weight condition are satisfied, even expensive special sheets such as coated sheets and high quality sheets which a user does not desire to use for cleaning may be used for cleaning. 
   SUMMARY 
   The present invention has been made in consideration of the above problems, and it is one of main objects to provide a technique to prevent expensive sheets and special sheets set in a sheet feeding tray from being unnecessarily used for cleaning a fusing section. 
   An image forming apparatus reflecting one aspect of the present invention comprises:
         a sheet feeding tray to store a sheet;   an image forming section to form a toner image on the sheet fed from the sheet feeding tray;   a fusing section to fuse the toner image on the sheet;   a controlling section to perform cleaning of the fusing section when a sheet has been nipped in the fusing section at a time of occurrence of a jam by passing a sheet from the sheet feeding tray through the fusing section after the jam is relieved;   an operating section to set an allowed condition including a sheet type and basis weight of an allowed sheet to be used for cleaning the fusing section; and   a memory section to store the allowed condition including the sheet type and basis weight set on the operating section, wherein   the controlling section determines whether or not the sheet feeding tray stores a sheet which satisfies the allowed condition stored in the memory section when cleaning of the fusing section is performed, and when the sheet feeding tray stores the sheet which satisfies the allowed condition, the controlling section selects the sheet feeding tray and controls the sheet feeding tray to feed the sheet from the selected sheet feeding tray and controls the fusing section to pass the sheet through the fusing section.       

   An image forming apparatus reflecting another aspect of the present invention comprises: 
   a sheet feeding tray to store a sheet; 
   an image forming section to form a toner image on the sheet fed from the sheet feeding tray; 
   a fusing section to fuse the toner image on the sheet; 
   a controlling section to perform cleaning of the fusing section when a sheet has been nipped in the fusing section at a time of occurrence of a jam by passing a sheet from the sheet feeding tray through the fusing section after the jam is relieved; 
   an operating section to set a prohibited condition including a sheet type and basis weight of a prohibited sheet not to be used for cleaning the fusing section; and 
   a memory section to store the prohibited condition including the sheet type and basis weight set on the operating section, wherein 
   the controlling section determines whether or not the sheet feeding tray stores a sheet which does not fall into the prohibited condition stored in the memory section when cleaning of the fusing section is performed, and when the sheet feeding tray stores the sheet which does not fall into the prohibited condition, the controlling section selects the sheet feeding tray and controls the sheet feeding tray to feed the sheet from the selected sheet feeding tray and controls the fusing section to pass the sheet through the fusing section. 
   According to the above aspects of the invention, when a cleaning of a fusing section is performed, a sheet which satisfies an allowed condition such as sheet type, basis weight, etc. set on the operating section is automatically fed from the sheet feeding tray which stores the sheet and passed to the fusing section. Consequently, even when expensive sheets and special sheets which a user does not desire to use for cleaning the fusing section are stored in any of the sheet feeding sections, such sheets can be prevented from being unnecessarily used when cleaning the fusing section. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, advantages and features of the present invention will become more fully understood from the detailed description given hereinbelow and the appended drawings, and thus are not intended as a definition of the limits of the present invention, and wherein; 
       FIG. 1  is a block diagram showing a functional structure of an image forming apparatus of the present embodiment; 
       FIG. 2A  is a diagram showing an example of data storage in a tray file; 
       FIG. 2B  is a diagram showing an example of data storage in a cleaning allowed condition file; 
       FIG. 3  is a diagram showing an example of a condition setting screen for setting cleaning allowed conditions displayed on an LCD shown in  FIG. 1 ; 
       FIG. 4  is a diagram showing a main structure of a printer shown in  FIG. 1 ; 
       FIG. 5  is a flow chart showing a cleaning controlling processing performed by a controlling section shown in  FIG. 1 ; 
       FIG. 6  is a diagram showing an example of a jam screen displayed on the LCD shown in  FIG. 1 ; 
       FIG. 7A  is a diagram schematically showing a wrapping jam in which a sheet wraps around a heating roller of a fusing section; 
       FIG. 7B  is a diagram schematically showing unfused toner adhering on the fusing section by the jam shown in  FIG. 7A ; 
       FIG. 8  is a diagram showing an example of a selecting screen displayed on the LCD shown in  FIG. 1 ; 
       FIG. 9  is a flow chart showing a sheet feeding tray selecting processing performed by the controlling section shown in  FIG. 1 ; 
       FIG. 10  is a diagram showing an example of a tray selecting screen displayed on the LCD shown in  FIG. 1 ; 
       FIG. 11  is a diagram schematically showing a heating roller and pressuring roller shown in  FIG. 4  being cleaned by passing a sheet and letting toner which is adhered to the heating roller and pressuring roller be adhered to the sheet; 
       FIG. 12  is a flow chart showing a cleaning controlling processing B performed by the controlling section shown in  FIG. 1 ; 
       FIG. 13  is a flow chart showing a sheet feeding tray selecting processing B performed by the controlling section shown in  FIG. 1 ; 
       FIG. 14  is a flow chart showing a cleaning controlling processing C performed by the controlling section shown in  FIG. 1 ; 
       FIG. 15  is a diagram showing an example of a condition setting screen of a cleaning prohibited condition displayed on an LCD shown in  FIG. 1 ; and 
       FIG. 16  is a flow chart showing a sheet feeding tray selecting processing C performed by the controlling section shown in  FIG. 1 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   First Embodiment 
   A first embodiment of the present invention will be described in detail below with reference to the drawings. 
   First, a structure is described. 
     FIG. 1  shows an example of a functional structure of an image forming apparatus  100  of the present embodiment. As shown in  FIG. 1 , the image forming apparatus  100  includes a main unit controlling section  10 , an operating section  20 , a scanner section  30 , a printing controller section  40 , and a printer section  50 . 
   The main unit controlling section  10  includes a controlling section  11 , a memory section  14 , a reading processing section  15 , a DRAM (Dynamic Random Access Memory) controlling IC  16 , a compressing/expanding IC  17 , a DRAM image memory  18 , a writing processing section  19 , and the like. 
   The controlling section  11  includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) and the like. The CPU of the controlling section  11  reads various processing programs such as a cleaning controlling processing program and a sheet feeding tray selecting program stored in the ROM and develops them to a work area of the RAM. Then, according to the developed programs, the CPU centrally controls operations of the sections of the image forming apparatus  100  and performs various processing such as the later described cleaning controlling processing and sheet feeding tray selecting processing. 
   The memory section  14  includes a nonvolatile memory and the like and stores a tray file  141  which stores setting information of a sheet feeding tray, a condition file  142  which stores a cleaning allowed condition, and the like according to instructions from the controlling section  FIG. 2A  shows an example of data storage in the tray file  141 . As shown in  FIG. 2A , the tray file  141  stores information on the sheet including sheet type (for example, plain sheet, coated sheet GL, high quality sheet), basis weight (for example, 75-80 g/m 2 , 136-162 g/m 2 , 64-74 g/m 2 ) and presence of punched hole (for example, none, . . . ) stored in each sheet feeding tray. The tray file  141  is setting information set and input through a tray setting screen (not shown) displayed on the operating section  20  according to a predetermined operation. 
     FIG. 2B  shows an example of data storage in the condition file  142 . The condition file  142  stores conditions of sheets allowed to be used in cleaning the fusing section, which are set and input from a cleaning allowed condition setting screen  220  (see  FIG. 3 ) displayed on the operating section  20  according to a predetermined operation. For example, as shown in  FIG. 2B , the file includes items “sheet type”, “basis weight”, “punched hole”, “index sheet”, “color sheet”, etc. In the item “sheet type”, the type of sheet (for example, plain sheet and high quality sheet) allowed to be used for cleaning the fusing section is stored. In the item “basis weight”, the basis weight (for example, 64-74 g/m 2 , 75-80 g/m 2 , 81-105 g/m 2 , and 106-135 g/m 2 ) of the sheet allowed to be used for cleaning the fusing section is stored. In the items “punched hole”, “index sheet” and “color sheet”, information on allowed condition for each item (for example, “allowed”) when such sheets used for cleaning the fusing section is stored. 
   The reading processing section  15  converts analog image signals read by the scanner section  30  to RGB image data then performs image processing such as converting RGB image data to CMYK image data and outputs the data to the DRAM controlling IC  16 . 
   Based on control by the controlling section  11 , the DRAM controlling IC  16  allows the compressing/expanding IC  17  to compress image data input from the reading processing section  15  and image data input from the printing controller section  40 , then writes the compressed image data on the compressed memory  18   a  of the DRAM image memory  18  so as to temporarily store the image data. When there is an instruction from the controlling section  11  to output image data, the DRAM controlling IC  16  allows the compressing/expanding IC  17  to expand the image data instructed to be output which is stored in the compressed memory  18   a , and stores the expanded image data in a page memory  18   b . Then according to an instruction from the controlling section  11 , the image data stored in the page memory  18   b  is read and output to the reading processing section  19 . 
   The compressing/expanding IC  17  performs compressing processing and expanding processing of image data according to control by the DRAM controlling IC  16 . 
   The DRAM image memory  18  is configured with a DRAM and includes the compressed memory  18   a  and the page memory  18   b . According to control by the DRAM controlling IC  16 , the compressed memory  18   a  temporarily stores image data compressed in the compressing/expanding IC  17 . The page memory  18   b  temporarily stores image data expanded in the compressing/expanding IC  17 . 
   The writing processing section  19  generates PWM (Pulse Width Modulation) signals according to image data input from compressing/expanding IC  17  and outputs the signals to printer section  50 . 
   The operating section  20  includes an operating controlling section  21  and an LCD (Liquid Crystal Display)  22 . 
   The operating controlling section  21  receives display signals from the controlling section  11  and controls the display of the LCD  22 . The operating controlling section  21  outputs to the controlling section  11  operating signals input from a touch panel on the LCD  22 . 
   The LCD  22  displays various operating screens, status of image, operation status of each function and the like according to instructions input as display signals from the operating controlling section  21 . On the screen of the LCD  22 , a pressure sensitive type (resistive film type) touch panel is provided in which transparent electrodes are arranged in a grid-like pattern, and an XY coordinate of a point pushed down with a finger or a touch pen, etc. is detected with a voltage level so as to output the detected location signal as an operating signal to the operating controlling section  21 . 
   For example, the LCD  22  displays a condition setting screen  220  for inputting the allowed conditions (sheet type, basis weight, etc.) of the sheets allowed to be used for cleaning the fusing section.  FIG. 3  shows an example of the condition setting screen  220 . As shown in  FIG. 3 , a condition setting screen  220  displays a sheet type selecting button group  220   a , a basis weight selecting button group  220   b , a punched hole allowed input button  220   c , an index sheet allowed input button  220   d , a color sheet allowed input button  220   e , and the like. The sheet type selecting button group  220   a  includes a plurality of operating buttons displaying various different sheet types respectively, and when an operating button is pushed down, the sheet type displayed in the operating button is stored in the condition file  142  of the memory section  14  as the sheet type of the sheet allowed to be used for cleaning the fusing section. The basis weight selecting button group  220   b  includes a plurality of operating buttons displaying various different basis weights respectively, and when an operating button is pushed down, the basis weight displayed in the operating button is stored in the condition file  142  of the memory section  14  as the basis weight of the sheet allowed to be used for cleaning the fusing section. When the punched hole allowed input button  220   c , the index sheet allowed input button  220   d , or the color sheet allowed input button  220   e  is pushed down, the information showing the punched hole is allowed, the information showing the index sheet is allowed, or the information showing the color sheet is allowed is stored in the condition file  142  of the memory section  14 , respectively (see  FIG. 2B ). 
   The operating section  20  includes other various operating buttons such as numeric buttons and a start button (not shown), and the operating signals by operating the buttons are output from the operating controlling section  21  to the controlling section  11 . 
   The scanner section  30  includes a scanner controlling section  31  and a scanner  32 . 
   The scanner controlling section  31  receives controlling signals from the controlling section  11  and drives and controls the sections of the scanner  32 . The scanner  32  includes platen glass, a CCD (Charge Coupled Device) and a light source. The scanner  32  scans an original document with a light source, focuses an image of the reflected light on a CCD (Charge Coupled Device), to perform an optoelectronic conversion, and thereby reads an image of the original document set in a predetermined position as an RGB signal. The read analog image signal is output to the reading processing section  15 . 
   The printing controller section  40  includes a controller controlling section  41 , a DRAM controlling IC  42 , an image memory  43 , and a LANIF  44 . 
   The controller controlling section  41  centrally controls the operation of the sections of the printing controller section  40 . The controller controlling section  41  converts the printing data input from the host computer  200  through the LANIF  44  to image data in a data format in which the image forming apparatus  100  can print the image with a predetermined page description language and outputs the data with the controlling data input from the host computer  200  to the DRAM controlling IC  42 . 
   The DRAM controlling IC  42  outputs the printing data and controlling data received from the LANIF  44  to the controller controlling section  41 . According to the instructions from the controller controlling section  41 , the DRAM controlling IC  42  controls the temporary storage of the image data and controlling data input from the controller controlling section  41  in the image memory  43 . The DRAM controlling IC  42  is connected to the DRAM controlling IC  16  of the main unit controlling section  10  through a PCI (Peripheral Components Interconnect) bus, and according to instructions from the controller controlling section  41 , reads out the image data and controlling data from the image memory  43 , and outputs the data to the DRAM controlling IC  16 . 
   The image memory  43  is configured with a DRAM and temporarily stores the input data. 
   The LANIF  44  includes an NIC (Network Interface Card), modem, and the like and sends/receives data such as printing data and controlling data to/from the host computer  200  connected to a communication network N such as a LAN (Local Area Network). The data received from the host computer  200  is output to the DRAM controlling IC  42 . 
   The printer section  50  includes a printer controlling section  51  and a printer  52 . 
   The printer controlling section  51  receives a controlling signal from the controlling section  11  and controls the operation of the sections of the printer  52 . 
   Based on the image data input from the controlling section  11 , the printer  52  forms and outputs a toner image on the sheet by electrophotography. 
     FIG. 4  shows the structure of a main section of the printer  52 . As shown in  FIG. 4 , the printer  52  includes an image forming section  501 , a paper feeding section  502 , and a fusing section  503 . 
   The image forming section  501  includes writing units  40 Y,  40 M,  40 C, and  40 K for writing latent images of the images on photoconductive drums  51 Y,  51 M,  51 C, and  51 K by exposing the photoconductive drums with lasers based on the PWM signal input from the writing processing section  19 . The image forming section  501  also includes photoconductive units  50 Y,  50 M,  50 C and  50 K for forming toner images of the colors Y, M, C, K, an intermediate transfer belt  56  as an intermediate transfer body, which is freely supported by the rollers  57  and carries toner images, formed on the photoconductive units  50 Y,  50 M,  50 C and  50 K to the sheet, a registration roller  58  for synchronizing with the toner images formed on the intermediate transfer belt  56  with the sheet and conveying it to a secondary transfer roller  59 , and the secondary transfer roller  59  for transferring the toner images formed on the intermediate transfer belt  56  to the sheet. The photoconductive unit  50 Y includes the photoconductive drum  51 Y, developing device  52 Y, charging device  53 Y, cleaner  54 Y and primary transfer roller  55 Y. The photoconductive units  50 M,  50 C, and  50 K have the same structure. 
   The sheet feeding section  502  includes sheet feeding trays  66 A to  66 C for storing sheets, sheet feeding rollers  68 A to  68 C for conveying sheets one by one from the sheet feeding trays  66 A to  66 C, a manual sheet feeding tray  67  and a manual sheet feeding roller  69  for conveying sheets one by one from the manual sheet feeding tray. 
   The fusing section  503  includes a heating roller  60  which is a heating component comprising a heating device inside such as a halogen lamp heater, an induction heater or the like and a pressure roller  62  which is a pressuring component imposed on the heating roller  60  to form a fusing nip portion. 
   The printer  52  is provided with a plurality of conveying rollers  63  for conveying the fed sheets along a predetermined conveying route inside the image forming apparatus  100  and the sheets fed from the sheet feeding section  502  are conveyed one by one on the conveying route. A sheet ejecting roller  61  for sending out the conveyed sheet is provided near a sheet ejecting opening and the sheet conveyed through the conveying route is ejected out from the ejecting opening. 
   Here, the image forming in the printer  52  is described. First, in the photoconductive unit  50 Y, the photoconductive drum  51 Y rotates, its surface is charged by the charging device  53 Y, and a latent image of an image of Y data is formed in the charged area by exposure with the laser light source of the writing unit  40 Y. The developing device  52 Y forms a yellow toner image in the area of the latent image. The toner image is transferred to the intermediate transfer belt  56  by imposing the primary transfer roller  55 Y (primary transferring). The toner image becomes the yellow image corresponding to the image data to be output. The toner which was not transferred is removed by the cleaner  54 Y. 
   In the photoconductive units  50 M,  50 C, and  50 K, a magenta toner image, a cyan toner image, and a black toner image are formed and transferred respectively with the same process. The rotation of the roller  57 , the primary transfer rollers  55 Y,  55 M,  55 C and  55 K, and the secondary transfer roller  59  rotates the intermediate transfer belt  56  and the toner images of the colors YMCK are transferred and overlapped in order on the intermediate transfer belt  56 . Any of the sheet feeding rollers  68 A to  68 C rotate so as to convey sheets one by one from any of the sheet feeding trays  66 A to  66 C and the registration roller  58  rotates so as to convey the sheet to the secondary transfer roller  59 . The sheet passes through the imposing portion of the secondary transfer roller  59  and the toner images of the colors YMCK on the intermediate transfer belt  56  are transferred to the sheet (secondary transferring). 
   The sheet on which the toner images of the colors YMCK were transferred passes through the fusing section  503 . The heating roller  60  and the pressure roller  62  of the fusing section  503  heats and presses the sheet while it is nipped with a fusing nip portion and conveyed, so that the toner images are melted and fused on the sheet. The sheet fused with the toner images by the fusing section  503  is ejected out by the sheet ejecting roller  61 . 
   After the image is formed on the sheet, the belt cleaning section  62  removes the toner remaining on the intermediate transfer belt  56 . Voltages of positive polarity and negative polarity are alternately applied to the secondary transfer roller  59  by a power source (not shown) for a predetermined amount of time and the toner adhered to the secondary transfer roller  59  is transferred back to the intermediate transfer belt  56  again so that the secondary transfer roller  59  is cleaned. 
   The sections of the above-described printer  52  are driven by various motors (not shown) under control of the printer controlling section  51 . A plurality of sensors such as SE 1 , SE 2 , and SE 3  are provided on the sheet conveying route. These sensors are connected to the printer controlling section  51 . When a passing of the sheet is detected, a sheet detect signal is generated and then output to the printer controlling section  51 . Based on the sheet detect signal output by these sensors, the printer controlling section  51  manages the conveying status and detects the occurring and relieving of a jam. 
   For example, when a front end of a sheet passes by a sensor and a sheet detect signal is output, but a sheet detect signal is not output within a predetermined time frame from the next sensor on the conveying route which the sheet is to pass through, a jam is detected between the two sensors and jam detect information including information on where the jam occurred is output to the controlling section  11 . When a sheet detected signal continues to be output from a certain sensor for at least a predetermined amount of time, a jam is detected near the certain sensor and the jam detect information including information on where the jam occurred is output to the controlling section  11 . 
   An open/close detecting sensor (not shown) which detects the opening and closing of the doors covering a front face of the image forming apparatus  100  is provided on the front face of the printer  52 . The open/close detecting sensor is connected to the printer controlling section  51 , and generates an open detect signal when a door is open which is then output to the printer controlling section  51 . When the open detecting signals input after the jam occurs is no longer input, the printer controlling section  51  determines whether or not there is a sheet detect signal from the sensors provided on the conveying route. When the sheet detect signal is not input from any of the sensors, the printer controlling section  51  detects that the jam has been relieved and outputs jam relieve information to the controlling section  11 . 
   Next, the operation of the present embodiment is described. 
     FIG. 5  shows the cleaning controlling processing performed by the controlling section  11  when jam detect information is input from the printer controlling section  51  during a printing operation. 
   When a jam occurs, the location of the jam included in the jam detect information is temporarily stored, and the operation of each section of the image forming apparatus  100  is stopped (step S 1 ). Then, the location information of the sheet remaining on the conveying route is queried to the printer controlling section  51  and obtained therefrom (step S 2 ). When the printer controlling section  51  receives the query of the location information of the sheet remaining on the conveying route, the location information of the sensor which is outputting the sheet detect signal after the operation is stopped is obtained and transmitted to the controlling section  11 . 
   Next, the obtained location information of the remaining sheet is temporarily stored and based on the jam detect information and the obtained location information of the remaining sheet, a jam screen  221  is displayed showing that a jam occurred, the location of the sheet to be removed (jam location and location of the remaining sheet), and the like (step S 3 ).  FIG. 6  is an example of the jam screen  221 . A user settles the jam according to the jam screen  221 . That is, the user opens the door corresponding to the sheet location shown on the jam screen  221 , removes the sheet remaining in the location and then closes the door. 
   After the jam screen  221  is displayed, whether or not the jam relieve information is input from the printer controlling section  51  is determined, and when it is determined that the jam relieve information is not input (step S 4 ; NO) the process returns to step S 3 . When it is determined that the jam relieve information is input (step S 4 ; YES), the process advances to step S 5 . 
   In step S 5 , based on the location information of the remaining sheet obtained by the printer controlling section  51  in step S 2 , it is determined whether or not the sheet was nipped in the fusing section  503  when the operation stopped due to the occurrence of the jam (step S 5 ). When the sheet detect signal was output from at least one of the sensors SE 1  or SE 2 , it is determined that the sheet was nipped in the fusing section  503 . When it is determined that the sheet was not nipped in the fusing section  503  when the operation stopped due to the occurrence of the jam (step S 5 ; NO), the process ends. When it is determined that the sheet was nipped in the fusing section  503  when the operation stopped due to the occurrence of the jam (step S 5 ; YES), a select screen  222  is displayed on the LCD  22  of the operating section  20  for selecting whether or not to instruct cleaning of the fusing section (step S 6 ). 
     FIG. 7A  to  FIG. 7B  schematically show a jam in the fusing section  503 . As shown in  FIG. 7A , when a wrapping jam where the sheet wraps around the heating roller  60  of the fusing section  503  occurs, the sensor SE 1  outputs the sheet detect signal for at least a predetermined amount of time, thus the printer controlling section  51  detects the jam. In this case, as shown in  FIG. 7A , the unfused toner on the nipped sheet is adhered on the heating roller  60 . Even when the jam is settled and the sheet is removed, the unfused toner remains adhered on the heating roller  60 , as shown in  FIG. 7B . This may also occur even when the jam occurs in a different section if the sheet is nipped in the fusing section  503  when the operation stops. As described above, when the printing is resumed with the unfused toner remaining on the heating roller  60 , the residual toner may adhere on the face of the image of the sheet fed just after the printing is resumed, resulting in a stain in the image, or the residual toner may transfer from the heating roller  60  to the pressuring roller  62  and adheres to the back face of the sheet fed just after printing is resumed, resulting a stain in the back face of the sheet. Therefore, in the image forming apparatus  100 , the select screen  222  is displayed on the LCD  22 , and according to a user&#39;s selection, a new sheet is fed to the fusing section  503  and passed through, and the cleaning of the fusing section is performed. 
     FIG. 8  shows an example of a select screen  222 . As shown in  FIG. 8 , the select screen  222  displays a “Yes” button  222   a  for inputting an instruction to perform the cleaning of the fusing section and a “No” button  222   b  for inputting an instruction not to perform the cleaning of the fusing section. 
   When the “No” button  222   b  on the select screen  222  is pushed down and an instruction not to perform the cleaning of the fusing section is input (step S 7 ; NO), the process ends. When the “Yes” button  222   a  on the select screen  222  is pushed down and an instruction to perform the cleaning of the fusing section is input (step S 7 ; YES), the sheet feeding tray selecting processing is performed (step S 8 ). 
     FIG. 9  shows the sheet feeding tray selecting processing performed by the controlling section  11 . 
   In the sheet feeding tray selecting processing, first the tray file  141  (see  FIG. 2A ) stored in the memory section  14  is read out and the setting information of all the sheet feeding trays is obtained (step S 101 ). Then, the condition file  142  (see  FIG. 2B ) stored in the memory section  14  is read out and the allowed conditions of the sheet allowed to be used in the cleaning of the fusing section is obtained (step S 102 ). 
   Next, a count value n is set to 1 (step S 103 ) and the sheet feeding tray which satisfies the allowed conditions stored in the condition file  142  is searched. That is, a nth sheet feeding tray is selected as the processing target (step S 104 ) and it is determined whether or not the setting of the sheet feeding tray selected as the processing target satisfies the allowed conditions stored in the condition file  142  (step S 105 ). When it is determined that the setting of the processing target sheet feeding tray does not satisfy the allowed conditions (step S 105 ; NO), then it is determined whether or not n≧total number of sheet feeding trays, i.e. whether or not the query of all of the sheet feeding trays is finished. When it is determined that it is not n≧total number of sheet feeding trays or the query of all of the sheet feeding trays is not finished, (step S 106 ; NO), the count value n is incremented by 1 (step S 107 ) and the process returns to step S 104 . 
   In step S 105 , when it is determined that the setting of the processing target sheet feeding tray satisfies the allowed conditions (step S 105 ; YES), this sheet feeding tray is determined to satisfy the allowed conditions and selected as the sheet feeding tray to be used in cleaning the fusing section (step S 110 ), and the process advances to step S 9  of  FIG. 5 . 
   In step S 106 , when n≧total number of sheet feeding trays, and it is determined that the query of all sheet feeding trays is finished (step S 106 ; YES), a tray selecting screen  223  is displayed on the LCD  22  (step S 108 ). 
     FIG. 10  shows an example of the tray selecting screen  223 . On the tray selecting screen  223  of  FIG. 10 , a list of contents such as sheet type, sheet size, basis weight and punched hole presence of the sheets stored in the sheet feeding tray  66 A to  66 C is displayed based on the tray file  141  stored in the memory section  14 . The tray selecting screen  223  also displays a numeric key pad, and the sheet number to be passed through during cleaning can also be input. 
   When any of the sheet feeding tray information is selected from the list displayed on the tray selecting screen  223  (step S 109 ; YES), the selected sheet feeding tray is selected to be used in cleaning the fusing section (step S 110 ), and the process advances to step S 9  of  FIG. 5 . 
   In step S 9  of  FIG. 5 , it is determined whether or not the sheet number to be passed has been already input. When it is determined that the sheet number has been already input (step S 9 ; YES) the process advances to step S 12 , and when it is determined that the sheet number has not been input (step S 9 ; NO), the input screen for inputting the sheet number to be passed is displayed on the LCD  22  (step S 10 ) and when the sheet number is input (step S 11 ; YES) the process advances to step S 12 . 
   In step S 12 , the process waits for pushing down of the start button of the processing section  20 , and when the start button is pushed down (step S 12 ; YES), the cleaning processing of the fusing section is performed (step S 13 ). That is, the information on the selected sheet feeding tray and the instruction to clean the fusing section is transmitted to the printer controlling section  51 . Then, according to the control of the printer controlling section  51 , in the printer  52 , the input number of sheets are fed one by one from the sheet feeding tray selected in the sheet feeding tray selecting processing and all of the rollers used to convey the sheets are driven so as to pass the fed sheets through the fusing section  503  and eject the sheets from the ejecting opening. With this, as shown in  FIG. 11 , the toner adhered on the heating roller  60  and the pressuring roller  62  is adhered onto the sheet which is passing through, thereby the heating roller  60  and the pressuring roller  62  is cleaned. 
   When the cleaning processing of the fusing section is finished, a screen querying whether or not to repeat the cleaning of the fusing section is displayed, and when another cleaning is instructed (step S 14 ; YES), the process returns to step S 8 . When an instruction not to repeat the cleaning is input (step S 14 ; NO), the process ends. After the process ends, the printing operation is resumed. 
   As described above, according to the image forming apparatus  100  of the first embodiment, in a case where a sheet is nipped in the fusing section  503  when a jam occurs, when cleaning of the fusing section is instructed by a user through the select screen  222  after the jam is relieved, a sheet feeding tray which stores the sheet allowed to be used in the cleaning of the fusing section predetermined on the condition setting screen  220  by a user, is searched, a sheet feeding tray storing the sheet which satisfies the allowed conditions is selected. The sheet from the selected sheet feeding tray is conveyed without forming an image and passed through the fusing section  503  for cleaning the fusing section. 
   Consequently, cleaning of the fusing section is performed by automatically feeding sheets from the sheet feeding tray storing the sheet which satisfies the allowed conditions such as the sheet type, basis weight, etc., allowed by the user. Therefore, even when expensive sheets and special sheets, which a user does not want to use for cleaning the fusing section, are stored in the sheet feeding tray, these sheets in cleaning the fusing section can be prevented from being unnecessarily used. 
   Second Embodiment 
   Next the second embodiment of the present invention is described. The structure of the image forming apparatus  100  of the second embodiment is the same as the structure described in the first embodiment, thus the description is omitted, and the operation of the second embodiment is described. 
     FIG. 12  shows the cleaning controlling processing (hereinafter referred to as cleaning controlling processing B) which is performed by the controlling section  11  when the jam detect information is input from the printer controlling section  51  during the printing operation. 
   The operation of steps S 21  to S 27  of the cleaning controlling processing B is the same as the steps S 1  to S 7  of the cleaning controlling processing described with  FIG. 5 , thus the description is omitted. 
   In step S 28 , the sheet feeding tray selecting processing (hereinafter referred to as sheet feeding tray selecting processing B) is performed.  FIG. 13  shows the sheet feeding tray selecting processing B performed by the controlling section  11 . 
   In the sheet feeding tray selecting processing B, first the tray file  141  (see  FIG. 2A ) stored in the memory section  14  is read out and the setting information of all the sheet feeding trays is obtained (step S 201 ). Then, the condition file  142  (see  FIG. 2B ) stored in the memory section  14  is read out and the allowed conditions of the sheet allowed to be used in the cleaning of the fusing section is obtained (step S 202 ). 
   Next, a count value n is set to 1 (step S 203 ) and the sheet feeding tray which satisfies the allowed conditions stored in the condition file  142  is searched. That is, a nth sheet feeding tray is selected as the processing target (step S 204 ) and it is determined whether or not the setting of the sheet feeding tray selected as the processing target satisfies the allowed conditions stored in the condition file  142  (step S 205 ). When it is determined that the setting of the processing target sheet feeding tray does not satisfy the allowed conditions (step S 205 ; NO), then it is determined whether or not n≧total number of sheet feeding trays, i.e. whether or not the query of all of the sheet feeding trays is finished. When it is determined that it is not n≧total number of sheet feeding trays or the query of all of the sheet feeding trays is not finished, (step S 206 ; NO), the count value n is incremented by 1 (step S 207 ) and the process returns to step S 204 . 
   In step S 205 , when it is determined that the setting of the processing target sheet feeding tray satisfies the allowed conditions (step S 205 ; YES), this sheet feeding tray is determined to satisfy the allowed conditions and selected as the sheet feeding tray to be used in cleaning the fusing section (step S 208 ), and the process advances to step S 29  of  FIG. 12 . 
   In step S 206 , when n≧total number of sheet feeding trays, and it is determined that the query of all sheet feeding trays is finished (step S 206 ; YES), and the process advances to step S 29  of  FIG. 12 . 
   In step S 29  of  FIG. 12 , it is determined whether or not the sheet feeding tray storing the sheet which satisfies the allowed condition of the cleaning of the fusing section is selected in sheet feeding tray selecting processing B. When the sheet feeding tray which satisfies the allowed condition is not selected, that is, it is determined that there is no sheet feeding tray storing the sheet which satisfies the allowed condition (step S 29 ; NO), a message for urging the setting of the sheet which satisfies the allowed condition of the cleaning of the fusing section in any one of the sheet feeding trays  66 A to  66 C is displayed on the LCD  22  (step S 30 ). After the message is displayed, when the sheet which satisfies the allowed condition is set in the sheet feeding tray and the change of setting of the sheet feeding tray is input on the operating section  20  (step S 31 ; YES), the process returns to step S 28 , and the sheet feeding tray selecting processing B is performed again. In step S 29 , when it is determined that there is a sheet feeding tray storing the sheets which satisfies the allowed conditions, (step S 29 ; YES), the input screen for inputting the sheet number to be passed when cleaning the fusing section is displayed on the LCD  22  (step S 32 ). When the sheet number to be passed through is input on the displayed input screen (step S 33 ; YES) the process advances to step S 34 . 
   In step S 34 , the process waits for pushing down of the start button, and when the start button is pushed down (step S 34 ; YES), the cleaning processing of the fusing section is performed (step S 35 ). That is, the information on the selected sheet feeding tray and the instruction to clean the fusing section is transmitted to the printer controlling section  51 . Then, according to the control of the printer controlling section  51 , in the printer  52 , the input number of sheets are fed one by one from the sheet feeding tray selected in the sheet feeding tray selecting processing B and all of the rollers used to convey the sheets are driven so as to pass the fed sheets through the fusing section  503  and eject the sheets from the ejecting opening. With this, as shown in  FIG. 11 , the toner adhered on the heating roller  60  and the pressuring roller  62  is adhered onto the sheet which is passing through, thereby the heating roller  60  and the pressuring roller  62  is cleaned. 
   When the cleaning processing of the fusing section is finished, a screen querying whether or not to repeat the cleaning of the fusing section is displayed, and when another cleaning is instructed (step S 36 ; YES), the process returns to step S 28 . When an instruction not to repeat the cleaning is input (step S 36 ; NO), the process ends. After the process ends, the printing operation is resumed. 
   As described above, according to the image forming apparatus  100  of the first embodiment, in a case where a sheet is nipped in the fusing section  503  when a jam occurs, when cleaning of the fusing section is instructed by a user through the select screen  222  after the jam is relieved, a sheet feeding tray which stores the sheet allowed to be used in the cleaning of the fusing section predetermined on the condition setting screen  220  by a user, is searched, a sheet feeding tray storing the sheet which satisfies the allowed conditions is selected. The sheet from the selected sheet feeding tray is conveyed without forming an image and passed through the fusing section  503  for cleaning the fusing section. 
   When a sheet feeding tray storing a sheet which satisfies the allowed condition allowing the sheet to be used in the cleaning of the fusing section, a message for urging the setting of the sheet which satisfies the allowed condition of the sheet allowed to be used in the cleaning of the fusing section in any one of the sheet feeding trays  66 A to  66 C is displayed on the LCD  22 . When a sheet which satisfies the allowed condition is set, the sheet feeding tray storing the sheet which satisfies the allowed condition of the sheet allowed to be used in the cleaning of the fusing section is searched again, and the sheet feeding tray storing the sheet which satisfies the allowed condition is selected, and the sheet from the selected sheet feeding tray is conveyed without forming an image and passed through the fusing section  503  for cleaning the fusing section. 
   Consequently, cleaning of the fusing section is performed by automatically feeding sheets from the sheet feeding tray storing the sheet which satisfies the allowed conditions such as the sheet type, basis weight, etc., allowed by the user. Therefore, even when expensive sheets and special sheets, which a user does not want to use for cleaning the fusing section, are stored in the sheet feeding tray, these sheets in cleaning the fusing section can be prevented from being unnecessarily used. 
   When a sheet which satisfies the allowed conditions set by the user is not stored in the sheet feeding tray, a message urging the setting of the sheet which satisfies the allowed conditions of the cleaning of the fusing section in the sheet feeding tray is displayed on the LCD  22 . Therefore, a user can recognize that the sheet which satisfies the allowed conditions is not stored and set the sheet which satisfies the allowed conditions in the sheet feeding tray which enables the cleaning of the fusing section with the sheets which satisfies the allowed conditions. 
   Third Embodiment 
   Next the third embodiment of the present invention is described. The structure of the image forming apparatus  100  of the third embodiment is the same as the structure described in the first embodiment, thus the description is omitted, and the operation of the third embodiment is described. 
     FIG. 14  shows the cleaning controlling processing (hereinafter referred to as cleaning controlling processing C) which is performed by the controlling section  11  when the jam detect information is input from the printer controlling section  51  during the printing operation. 
   The operation of steps S 41  to S 48  of the cleaning controlling processing C is the same as the steps S 21  to S 28  of the cleaning controlling processing B described with  FIG. 12 , thus the description is omitted. 
   In step S 49 , in the sheet feeding tray selecting processing B, it is determined whether or not the sheet feeding tray which satisfies the allowed conditions of the cleaning of the fusing section is selected. When the sheet feeding tray which satisfies the allowed conditions is selected, that is, it is determined that there is a tray which satisfies the allowed conditions (step S 49 ; YES), the process advances to step S 53 . 
   When the sheet feeding tray which satisfies the allowed conditions is not selected, that is, it is determined that there is no sheet feeding tray which satisfies the allowed conditions (step S 49 ; NO), a message for urging the setting of the sheet which satisfies the allowed condition of the cleaning of the fusing section in the manual sheet feeding tray  67  is displayed on the LCD  22  (step S 50 ). After the message is displayed, when the sensor SE 3  detects that the sheet is set in the manual sheet feeding tray  67  (step S 51 ; YES), the manual sheet feeding tray  67  is selected as the sheet feeding tray for the cleaning of the fusing section, and the process advances to step S 53 . 
   In step S 53 , the input screen for inputting the sheet number to be passed during the cleaning of the fusing section is displayed on the LCD  22  (step S 53 ). When the sheet number to be passed is input from the displayed input screen (step S 54 ; YES) the process advances to step S 55 . 
   In step S 55 , the process waits for pushing down of the start button, and when the start button is pushed down (step S 55 ; YES), the cleaning processing of the fusing section is performed (step S 54 ). That is, the information on the selected sheet feeding tray and the instruction to clean the fusing section is transmitted to the printer controlling section  51 . Then, in the printer  52 , the input number of sheets is fed one by one from the selected sheet feeding tray and all of the rollers used to convey the sheets are driven so as to pass the fed sheets through the fusing section  503  and eject the sheets from the ejecting opening. With this, as shown in  FIG. 11 , the toner adhered on the heating roller  60  and the pressuring roller  62  is adhered onto the sheet which is passing through, thereby the heating roller  60  and the pressuring roller  62  is cleaned. 
   When the cleaning processing of the fusing section is finished, a screen querying whether or not to repeat the cleaning of the fusing section is displayed, and when another cleaning is instructed (step S 57 ; YES), the process returns to step S 48 . When an instruction not to repeat the cleaning is input (step S 57 ; NO), the process ends. After the process ends, the printing operation is resumed. 
   As described above, according to the image forming apparatus  100  of the first embodiment, in a case where a sheet is nipped in the fusing section  503  when a jam occurs, when cleaning of the fusing section is instructed by a user through the select screen  222  after the jam is relieved, a sheet feeding tray which stores the sheet allowed to be used in the cleaning of the fusing section predetermined on the condition setting screen  220  by a user, is searched, a sheet feeding tray storing the sheet which satisfies the allowed conditions is selected. The sheet from the selected sheet feeding tray is conveyed without forming an image and passed through the fusing section  503  for cleaning the fusing section. 
   When a sheet feeding tray storing a sheet which satisfies the allowed conditions allowing the sheet to be used in the cleaning of the fusing section, a message for urging the setting of the sheet which satisfies the allowed condition of the sheet allowed to be used in the cleaning of the fusing section in the manual sheet feeding tray  67  is displayed on the LCD  22 . When a sheet which satisfies the allowed condition is set in the manual sheet feeding tray, the manual sheet feeding tray  67  is selected as the sheet feeding tray, and the sheet from the manual sheet feeding tray is conveyed without forming an image and passed through the fusing section  503  for cleaning the fusing section. 
   Consequently, cleaning of the fusing section is performed by automatically feeding sheets from the sheet feeding tray storing the sheet which satisfies the allowed conditions such as the sheet type, basis weight, etc., allowed by the user. Therefore, even when expensive sheets and special sheets, which a user does not want to use for cleaning the fusing section, are stored in the sheet feeding tray, of these sheets in cleaning the fusing section can be prevented from being unnecessarily used. 
   When a sheet which satisfies the allowed conditions set by the user is not stored in the sheet feeding tray, a message urging the setting of the sheet which satisfies the allowed conditions of the cleaning of the fusing section in the manual sheet feeding tray  67  is displayed on the LCD  22 . Therefore, a user can recognize that the sheet which satisfies the allowed conditions is not stored and set the sheet which satisfies the allowed conditions in the manual sheet feeding tray which enables the cleaning of the fusing section with the sheets which satisfies the allowed conditions. The sheets for cleaning the fusing section is set in the manual sheet feeding section, thus troublesome operation such as taking out the sheets already stored in the sheet feeding trays  66 A to  66 C, setting sheets for cleaning the fusing section then setting the originally set sheets again after cleaning the fusing section is not necessary, which enhances the convenience. 
   Fourth Embodiment 
   Next, the fourth embodiment of the present invention is described. 
   The structure of the above described first to third embodiments enables a user to set a sheet type, basis weight, etc. of the sheet allowed to be used in the cleaning of the fusing section. In the present embodiment, a user can set a sheet type, basis weight, etc. of the sheet prohibited to be used in the cleaning of the fusing section. 
   Specifically, the structure of the image forming apparatus  100  of the fourth embodiment is the same as the structure of the first embodiment, but a condition setting screen  224  for setting prohibited conditions of the cleaning is displayed in the operating section  20  and the condition file  143  which stores the prohibited conditions of the cleaning is stored in the memory section  14  instead of the condition file  142 . 
     FIG. 15  shows an example of a condition setting screen  224 . The condition setting screen  224  is an operating screen for setting conditions of the sheet prohibited to be used in the cleaning of the fusing section. As shown in  FIG. 15 , a sheet type selecting button group  224   a , a basis weight selecting button group  224   b , a punched hole prohibited input button  224   c , an index sheet prohibited input button  224   d , and a color sheet prohibited input button  224   e  are displayed. The sheet type selecting button group  224   a  includes a plurality of operating buttons displaying various different sheet types respectively, and when an operating button is pushed down, the sheet type displayed in the operating button is stored in the condition file  143  of the memory section  14  as the sheet type of the sheet prohibited to be used for cleaning the fusing section. The basis weight selecting button group  224   b  includes a plurality of operating buttons displaying various different basis weights respectively, and when an operating button is pushed down, the basis weight displayed in the operating button is stored in the condition file  143  of the memory section  14  as the basis weight of the sheet prohibited to be used for cleaning the fusing section. When the punched hole prohibited input button  224   c , the index sheet prohibited input button  224   d , or the color sheet prohibited input button  224   e  is pushed down, the information showing the punched hole is prohibited, the information showing the index sheet is prohibited, or the information showing the color sheet is prohibited is stored in the condition file  143  of the memory section  14 , respectively. 
   The condition file  143  is a file which stores conditions (sheet type, basis weight, punched hole, index sheet, and color sheet) of a sheet prohibited to be used in cleaning the fusing section which are set and input from a condition setting screen  224  on the operating section  20 . The structure of the data storage is the same as shown in  FIG. 2B , including items “sheet type”, “basis weight”, “punched hole”, “index sheet”, “color sheet”, etc, but in the condition file  143 , the information of the sheet type, basis weight, etc. prohibited to be used in the cleaning of the fusing section is stored. 
   The other structures are the same as those described in the first embodiment, thus the description is omitted. 
   Next, the operation of the fourth embodiment is described. 
   In the present embodiment, the cleaning controlling processing performed when the jam detect information is input from the printer controlling section  51  is the same as the cleaning controlling processing described in the first embodiment with reference to  FIG. 5 , but the contents of the operation of the sheet feeding tray selecting processing in step S 8  is different from the first embodiment. 
   The sheet feeding tray selecting processing of the fourth embodiment (hereinafter referred to as sheet feeding tray selecting processing C) is described. 
     FIG. 16  shows the sheet feeding tray selecting processing C performed by the controlling section  11 . 
   In the sheet feeding tray selecting processing C, first the tray file  141  (see  FIG. 2A ) stored in the memory section  14  is read out and the setting information of all the sheet feeding trays is obtained (step S 301 ). Then, the condition file  143  (see  FIG. 2B ) stored in the memory section  14  is read out and the prohibited conditions of the sheet prohibited to be used in the cleaning of the fusing section is obtained (step S 302 ). 
   Next, a count value n is set to 1 (step S 303 ) and the sheet feeding tray storing a sheet which does not fall into any of the prohibited conditions stored in the condition file  143  is searched. That is, a nth sheet feeding tray is selected as the processing target (step S 304 ) and it is determined whether or not the setting of the sheet feeding tray selected as the processing target (that is, the contents of the sheet stored in the processing target sheet feeding tray) falls into any of the prohibited conditions stored in the condition file  143  (step S 305 ). When it is determined that the setting of the processing target sheet feeding tray falls into any of the prohibited conditions (step S 305 ; YES), then it is determined whether or not n≧total number of sheet feeding trays, i.e. whether or not the query of all of the sheet feeding trays is finished. When it is determined that it is not n≧total number of sheet feeding trays or the query of all of the sheet feeding trays is not finished, (step S 306 ; NO), the count value n is incremented by 1 (step S 307 ) and the process returns to step S 304 . 
   In step S 305 , when it is determined that the setting of the processing target sheet feeding tray does not fall into any of the prohibited conditions (step S 305 ; NO), this sheet feeding tray determined not to fall into any of the prohibited conditions is selected as the sheet feeding tray to be used in cleaning the fusing section (step S 310 ) and the process advances to step S 9  of  FIG. 5 . 
   In step S 306 , when n≧total number of sheet feeding trays, and it is determined that the query of all sheet feeding trays is finished (step S 306 ; YES), a tray selecting screen  223  is displayed on the LCD  22  (step S 308 ). 
   When any of the sheet feeding tray information is selected from the list displayed on the tray selecting screen  223  (step S 309 ; YES), the selected sheet feeding tray is selected as the sheet feeding tray used in cleaning the fusing section (step S 310 ), and the process advances to step S 9  of  FIG. 5 . 
   From the step S 9  of  FIG. 5  and after, the processing is performed the same as described in the first embodiment. 
   As described above, according to the image forming apparatus  100  of the fourth embodiment, in a case where a sheet is nipped in the fusing section  503  when a jam occurs, when cleaning of the fusing section is instructed by a user through the select screen  222  after the jam is relieved, a sheet feeding tray, which stores the sheet which does not fall into any of the prohibited conditions prohibited to be used in the cleaning of the fusing section predetermined on the condition setting screen  224  by a user, is searched, a sheet feeding tray storing the sheet which does not fall into any of the prohibited conditions is selected. The sheet from the selected sheet feeding tray is conveyed without forming an image and passed through the fusing section  503  for cleaning the fusing section. 
   Consequently, cleaning of the fusing section is performed by automatically feeding sheets from the sheet feeding tray set with the sheet which does not fall into any of the prohibited conditions such as the sheet type, basis weight, etc., prohibited to be used in cleaning the fusing section by the user. Therefore, even when expensive sheets and special sheets, which a user does not want to use for cleaning the fusing section, are set in the sheet feeding tray, these sheets in cleaning the fusing section can be prevented from being unnecessarily used. 
   The first to fourth embodiments have been described, however, the contents described in the above described embodiments are suitable examples of the image forming apparatus  100  of the present invention and it is not limited to these embodiments. 
   For example, in the above described fourth embodiment, as a result of the query of the sheet feeding trays, when a sheet feeding tray storing a sheet which does not fall into any of the prohibited conditions of the sheet prohibited to be used preset by a user on the condition setting screen  224  is not found, a message urging the setting in the sheet feeding tray a sheet which does not fall into any of the prohibited conditions in cleaning of the fusing section may be displayed on the LCD  22 . Alternatively, a message urging the setting in the manual sheet feeding tray a sheet which does not fall into any of the prohibited conditions of the cleaning of the fusing section may be displayed on the LCD  22 . 
   The details of the structure of the devices and the details of the operation of the image forming apparatus  100  may be changed accordingly within the scope of the present invention. 
   The present U.S. patent application claims priority under the Paris Convention of Japanese Patent Application No. 2007-017856 filed on Jan. 29, 2007 to the Japanese Patent Office, which shall be a basis for correcting mistranslations.