Patent Publication Number: US-8983327-B2

Title: Fixing control apparatus, fixing control program product, and image forming apparatus

Description:
The present application is based on and claims the benefit of priority of Japanese Priority Application No. 2012-157681 filed on Jul. 13, 2012 and Japanese Priority Application No. 2013-038908 filed on Feb. 28, 2013, the entire contents of which are hereby incorporated by reference. 
     TECHNICAL FIELD 
     The present invention relates to fixing control apparatuses which fix, onto a recording material, an unfixed toner image formed based on image data; fixing control program products; and image forming apparatuses. 
     BACKGROUND ART 
     Related-art image forming apparatuses include an image foaming apparatus provided with a fixing apparatus using a laser beam, etc., or a thermal head which has a good thermal responsiveness. In the image forming apparatus provided with the fixing apparatus, a technique is known which selectively heats only a position at which toner is put on the recording material or only the vicinity thereof to fix non-fixed toner based on digital image data (Patent Document 1). 
     Patent Document 
     Patent Document 1 JP7-225524A 
     In the related art described above, fixing control is performed using write control data based on the digital image data. However, handling of the write control data is difficult, since an amount of data thereof is large. 
     DISCLOSURE OF THE INVENTION 
     The present invention is made to solve the problems described above in light thereof. 
     An object of the present invention is to provide a fixing control apparatus, a fixing control program product, and an image forming apparatus that make it possible to reduce an amount of data used in fixing control so as to fix toner efficiently. 
     According to an embodiment of the present invention, a fixing control apparatus which controls a fixing apparatus which includes multiple heating elements to fix, to a recording material, an unfixed toner image famed based on image data is provided, including an image presence/absence determining unit which determines the presence/absence of an image for each of multiple areas into which the image data are divided; a heating element selecting unit which selects a heating element located at a position corresponding to an area in which the image is present from the multiple heating elements; and a heating element driving unit which causes the heating element selected by the heating element selecting unit to be heated. 
     According to another embodiment of the present invention, a fixing control program product which is to be executed by a fixing control apparatus which controls a fixing apparatus which includes multiple heating elements to fix, to a recording material, an unfixed toner image formed based on image data is provided, the fixing control program product including the step of causing the fixing control apparatus to execute the image presence/absence determining step which determines presence/absence of an image for each of multiple areas into which the image data are divided; 
     a heating element selecting step of selecting a heating element located at a position corresponding to an area in which the image is present from the multiple heating elements; and 
     a heating body driving step of causing the heating element selected in the heating element selecting step to be heated. 
     According to a further embodiment of the present invention, an image forming apparatus is provided, including a fixing control apparatus which controls a fixing apparatus which includes multiple heating elements to fix, to a recording material, unfixed toner image formed based on image data, wherein the fixing control apparatus includes an image presence/absence determining unit which determines presence/absence of an image for each of multiple areas into which the image data are divided; a heating element selecting unit which selects a heating element located at a position corresponding to an area in which the image is present from the multiple heating elements; and a heating element driving unit which causes the heating element selected by the heating element selecting unit to be heated. 
     Embodiments of the present invention make it possible to reduce an amount of data handled at a time of fixing control and to fix toner efficiently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features, and advantages of the present invention will become more apparent from the following detailed descriptions when read in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram illustrating a schematic configuration of an image forming apparatus according to the present embodiment; 
         FIGS. 2A and 2B  are diagrams for explaining a fixing roller according to the present embodiment; 
         FIG. 3  is a diagram for explaining the configuration of the image forming apparatus according to the present embodiment; 
         FIG. 4  is a view for explaining a function of an image region determining unit; 
         FIG. 5  is a diagram which explains determining of an area in image data; 
         FIG. 6  is a view for explaining determining by an image presence/absence determining unit; 
         FIG. 7  is a diagram for explaining temperature control of a fixing apparatus at a time of image forming; 
         FIG. 8  is a flowchart for explaining an operation of the image forming apparatus; 
         FIG. 9  is a flowchart for explaining a process of a heating element selecting unit; 
         FIG. 10  is a diagram for explaining allocation of an area of image data to a heating element; and 
         FIGS. 11A and 11B  are diagrams showing an example of allocation of the area to the heating element when a width of the area is the same as a width of the heating element. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     A description is given below with regard to embodiments of the present invention with reference to the drawings.  FIG. 1  is a diagram illustrating a schematic configuration of an image forming apparatus according to the present embodiment. 
     An image forming apparatus  100  according to the present embodiment includes a scanner unit  110  and a printer unit  120 . In the image forming apparatus  100  of the present embodiment, the scanner unit  110  converts a reflected light of a read manuscript (not shown) into an electrical signal and further converts an analog electrical signal into a digital image signal to output the converted result to the printer unit  120 . Based on image data input from the scanner unit  110  or image data transmitted from a computer, etc., connected to the image forming apparatus  100 , the printer unit  120  performs an image forming operation. 
     The printer unit  120  according to the present embodiment includes a photoreceptor drum  121 , a charger  122 , a write apparatus  123 , a developing apparatus  124 , a paper-feeding apparatus  125 , a transfer apparatus  126 , a separating apparatus  127 , a fixing apparatus  128 , etc. 
     In the present embodiment, the photoreceptor drum  121  is uniformly charged by the charger  122 . The image data input into the image forming apparatus  100  undergo processes such as various conversions, magnification changes, etc., and various corrections, after which the processed image data are input into the write apparatus  123 . Based on image data input, the write apparatus  123  irradiates a laser light into the photoreceptor drum  121  based on input image data. An electrostatic latent image formed on the photoreceptor drum  121  is developed by thermally soluble toner by the developing apparatus  124  and turned into a visible image. On the other hand, a recording material (not shown) is fed by a paper-feeding roller  131  from the paper-feeding apparatus  125  and conveyed to a regist roller  133  via a conveying roller  132 . The regist roller  133  sends out the recording material in synchronization with a toner image on the photoreceptor drum  121 . Onto this recording material, the toner image on the photoreceptor drum  121  is transferred by an action of the transfer apparatus  126 . 
     Then, the recording material is separated from the photoconductor drum  121  by an action of the separating apparatus  127  and directed to the fixing apparatus  128 , being guided by a conveying guide  134 . An unfixed toner image on the recording material is heated and fixed by the fixing apparatus  128  and the recording material is discharged out the machine by a paper-discharging roller  135 . Moreover, in the photoreceptor drum  121 , after separating the recording material, residual toner is removed by a cleaning apparatus  136  and residual charges are erased by a discharger  137 . 
     In the image forming apparatus  100  according to the present embodiment, image data input into the write apparatus  123  are used to perform fixing control in the fixing apparatus  128 . In other words, the image forming apparatus  100  according to the present embodiment forms, on the recording material, the toner image formed on the photoreceptor drum  121  based on the image data. 
     Below, the fixing apparatus  128  of the present embodiment is explained. The fixing apparatus  128  according to the present embodiment includes a fixing roller  129  and a pressurizing roller  130 , and a fixing belt  138 . In the fixing apparatus  128  according to the present embodiment, the recording material is placed between the fixing roller  129  and the pressurizing roller  130  and conveyed therebetween, so that the unfixed toner image is fixed onto the recording material. 
       FIGS. 2A and 2B  are diagrams for explaining a fixing roller according to the present embodiment.  FIG. 2A  is a diagram for explaining a schematic configuration of the fixing roller  129 , while  FIG. 2B  is a diagram for explaining a heating element  200 . 
     Inside the fixing roller  129  according to the present embodiment is provided the heating element  200 . The heating element  200  includes multiple heating elements  30 N, for example. 
     The heating element  200  is explained with reference to  FIG. 2B . The heating element  200  according to the present embodiment includes the multiple heating elements  30 N. The multiple heating elements  30 N according to the present embodiment may have respectively different sizes or respectively the same size. In an example in  FIG. 2B , an example is shown in which the respective heating elements  30 N have different sizes. More specifically, the respective widths of the heating elements N in the main scanning direction differ. 
     In the present embodiment, a width A 4  in a main scanning direction of a heating element  304  which is located at a center portion in a main scanning direction of the fixing roller  129  is set to be wider than a width AN in a main scanning direction of the heating element  30 N near an end portion of the fixing roller  129 . More specifically, a width A 1  of a heating element  301  which is at one end portion in the main scanning direction of the fixing roller  129 , a width A 2  of a heating element  302 , and a width AN of the heating element  30 N which is at the other end portion in the main scanning direction of the fixing roller  129  are narrower than the width A 4  of the heating element  304 . A width A 3  in the main scanning direction of a heating element  303  is set to be wider than the width A 2  in the main scanning direction of the heating element  302  and narrower than the width A 4  in the main scanning direction of the heating element  304 . 
     At the center portion in the main scanning direction of the fixing roller  129 , there is a large possibility that the unfixed toner image is foamed. Therefore, in the present embodiment, the heating element  304  with a wide width in the main scanning direction is arranged at the center portion. The heating element may be arranged in this way to reduce the number of heating elements  30 N to be arranged and to simplify control of the heating element  30 N. Moreover, in the present embodiment, a width of the heating element at both end portions in the main scanning direction of the fixing roller  129  is set to be narrower than a width of the heating element arranged at a center portion in the main scanning direction. In this way, in both end portions in the main scanning direction of the recording material, the heating element may be left turned off in correspondence with a region in which the unfixed toner image is not formed. 
     The heating element  30 N according to the present embodiment heats a region of a length W in a sub-scanning direction x the same width as a width AN in the main scanning direction in the fixing roller  129 . In the present embodiment, the length W in the sub-scanning direction of the respective heating elements  30 N is set to be all the same. In the present embodiment, it is preferable that the number and the width AN in the main scanning direction of the heating elements  30 N is determined such that a width H in the main scanning direction of the heating element  200  and a width in the main scanning direction of the recording material match. The respective heating elements are controlled such that they are individually turned on and turned off. 
     The multiple heating elements  30 N according to the present embodiment may be realized by a thermal head array, an IH (induction heating) coil, etc., for example. 
     Next, a configuration of the image forming apparatus  100  according to the present embodiment is explained.  FIG. 3  is a diagram for explaining a configuration of the image forming apparatus according to the present embodiment. 
     The image forming apparatus  100  according to the present embodiment includes a controller control unit  210 , an engine control unit  220 , an HDD (hard disk drive)  230 , a FAX unit  231 , an operation control unit  232 , a read control unit  233 , an ARDF (automated reverse double-sided manuscript sending apparatus)  234 , a write control unit  235 , electric equipment units  236 , a DC (direct current) power supply  237 , an AC (alternating current) power supply  238 , etc. 
     The controller control unit  210  according to the present embodiment accepts designation of an image forming operation and sets the image forming operation. More specifically, the controller control unit  210  manages control, etc., of applications such as image forming, user interfacing, mode setting, copying, printer, etc. 
     The engine control unit  220  performs drive control, etc., of a printer engine. 
     In the HDD  230 , data, etc., to be processed are stored, for example. The FAX unit  231  realizes a FAX function in the image forming apparatus  100 . The operation control unit  232  performs control such as a touch panel (an operating unit) to be a user interface. 
     The read control unit  233 , which controls the scanner unit  110 , transmits an image read via a PCI (peripheral component interconnect) bus to an image processing unit  214  of the controller control unit  210 . 
     The write control unit  235  transmits image data sent via the PCI bus from the controller control unit  210  and the read control unit  233  to an LED (light emitting diode) unit and an LD (laser diode) unit performing image forming to perform an operation such as writing a pattern to a sheet and an operation such as printing and copying. 
     The various electric equipment components  236  include, for example, a temperature sensor, a motor, a solenoid, etc. The DC power supply  237  and the AC power supply  238  provide power to the respective control units. 
     Next, a configuration of the controller control unit  210  according to the present embodiment is explained. The controller control unit  210  according to the present embodiment includes a CPU (central processing unit)  211 , a RAM (random access memory)  212 , a ROM (read-only memory)  213 , an image processing unit  214 , an image memory  215 , and an I/F (interface)  216 . 
     The CPU  211  performs various processing operations. The RAM  212  temporally stores various information sets. The ROM  213  stores control programs in a fixed manner. The image processing unit  214  is realized by an ASIC (application specific integrated circuit), etc., which performs image processing, for example. In the image memory  215 , image data processed by the image processing unit  214  is stored. Moreover, the controller control unit  210  according to the present embodiment may include an NVRAM (non-volatile RAM) (not shown), etc., in which NVRAM may be stored setting information on operating conditions, etc., of the image forming apparatus  100 . 
     The controller control unit  210  according to the present embodiment is connected to the HDD  230  which stores predetermined data to be processed; the operation control unit  232  to be a user interface; the interface  216  which transmits and receives information via an LAN (local area network), etc., via a network from an external communications equipment unit. 
     The controller control unit  210  according to the present embodiment is connected by a PCI bus with the interface  216 , the engine control unit  220 , and the FAX unit  231 . The controller control unit  210  accepts instructions for an image foaming operation via the interface  216  from an external equipment unit or the operation control unit  232 , executes the image forming operation, and transmits the formed image to the engine control unit  220  via the PCI bus. 
     The engine control unit  220  according to the present embodiment includes a CPU  300 , a RAM  221 , a ROM  222 , and an electric equipment control unit  223 . The CPU  300  performs various operations of the engine control unit  220 . Moreover, the CPU  300  of the present embodiment performs fixing control by the fixing apparatus  128 . Details of fixing control by the CPU  300  will be described below. 
     The RAM  221  temporally stores various information sets. In the ROM  222  are stored control programs. In the present embodiment, fixing control programs may be stored in the ROM  222 . Moreover, in the ROM  222  of the present embodiment may be stored heating element information  22  which is described below. The electric equipment control unit  223  controls the electric equipment units  236 . 
     Below, functions of the CPU  300  will be explained. The CPU  300  according to the present embodiment includes a fixing control unit  350 . 
     The fixing control unit  350  includes an image region determining unit  310 , a heating element selecting unit  320 , and a heating element driving unit  310 . With image data received from the controller control unit  210  being set to be data for each predetermined region (area), the image region determining unit  310  determines presence/absence of an image in each area. Details of processing of the image region determining unit  310  will be described below. The heating element selecting unit  320  selects the heating element  30 N to be actually heated in accordance with an area in which the image is present. The heating element driving unit  330  drives and heats the heating element  30 N selected. 
     In other words, in the image forming apparatus  100  according to the present embodiment, with image data output from the image processing unit  214  being set to be data for each predetermined area which is pre-set by the image region determining unit  310 , presence/absence of an image for each area is determined. Next, the heating element selecting unit  320  selects the heating element  30 N corresponding to an area in which the image is present and allocates the area to the corresponding heating element  30 N. The heating element driving unit  330  drives and heats the heating element  30 N selected. 
     As a function not shown, the image forming apparatus  100  according to the present embodiment also includes a heating element temperature monitoring function by a temperature sensor which monitors a temperature state of the heating element  200 . 
     Moreover, while the present embodiment is configured to install the image region determining unit  310  within the engine control unit  220 , the image region determining unit  310  may be installed within the image processing unit  214  of the controller control unit  210 . In this case, results of processing by the image region determining unit  310  may be reported from the controller control unit  210  to the engine control unit  220 . 
     Next, with reference to  FIG. 4 , details of processing of the image region determining unit  310  of the present embodiment are explained.  FIG. 4  is a view for explaining a function of the image region determining unit. 
     The image region determining unit  310  of the present embodiment includes an image reading unit  311 , a pixel counting unit  312 , an image presence/absence determining unit  313 , and a heating position determining unit  314 . 
     Into the image reading unit  311  according to the present embodiment are read image data which are input via the controller control unit  210 . The image data read into may be temporarily stored into the RAM  221  within the engine control unit  220 . 
     The pixel counting unit  312  counts pixels of the image data. Details of the pixel counting unit  312  will be described below. 
     The image presence/absence determining unit  313  determines presence/absence of an image within an area for each predetermined area included in the image data. Details of determining by the image presence/absence determining unit  313  will be described below. The heating position determining unit  314  determines the heating element  30 N corresponding to an area in which the image is present to be a heating position. 
     Below, the pixel counting unit  312  is described. 
     The pixel counting unit  312  according to the present embodiment includes a main scanning counting unit  315  and a sub-scanning counting unit  316 . The main scanning counting unit  315  counts pixels in the main scanning direction of the image data. The sub-scanning counting unit  316  counts pixels in the sub-scanning direction of the image data. 
     When the image reading unit  311  reads in the image data, the pixel counting unit  312  of the present embodiment counts pixels in the main scanning direction by the main scanning counting unit  315 . In other words, the main scanning counting unit  315  counts a width of one line in the image data. The sub-scanning counting unit  316  counts pixels in the sub-scanning direction of the image data. In other words, the sub-scanning counting unit  316  counts the number of lines in the image data. 
     The image region determining unit  310  according to the present embodiment counts pixels in the respective main scanning and sub-scanning directions by the pixel counting unit  312  to determine the image data as a set of areas set in advance. 
     Below, determining of an area according to the present embodiment is described with reference to  FIG. 5 .  FIG. 5  is a diagram which explains determining of the area in image data. 
     In the present embodiment, image data are grasped as a set Emn of m rows×n columns of a predetermined area E which is set in advance. In the present embodiment, the predetermined area E is set to be a region of X×Y. Units of X and Y are both millimeters. 
     Moreover, in the present embodiment, a register corresponding to each predetermined area E is provided in a storage region which the CPU  300  has, for example. In an example in  FIG. 5 , the image data are a set of m rows×n columns of the area E, so that a register corresponding to the respective areas E 11  to Emn is provided in the storage area of the CPU  300 . Into this register is stored a count value by the pixel counting unit  312 . 
     The pixel counting unit  312  according to the present embodiment starts counting pixels of image data in order, starting from upper left of the image data. 
     The main scanning counting unit  315  of the pixel counting unit  312  counts pixels in the main scanning direction from upper left of the image data G shown in  FIG. 5  and stores a count value for each pixel into a register corresponding to each area E. 
     For example, the main scanning counting unit  315  starts counting pixels on a first line from upper left of the image data G. Here, the pixel counted is a pixel within an area E 11 . Therefore, the main scanning counting unit  315  stores a count value into a register corresponding to the area E 11 . In other words, until pixels are counted which correspond to X millimeters in the main scanning direction, the main scanning counting unit  315  stores the count value in a register corresponding to the area E 11 . Therefore, a value of a register becomes a sum of count values of pixels which form the first line within the area E 11 . 
     Next, when pixels to be counted becomes pixels within an area E 12 , the main scanning counting unit  315  stores the count value into a register corresponding to the area E 12 . Then, until pixels are counted which correspond to X millimeters in the main scanning direction from the first pixel within the area E 12 , the main scanning counting unit  315  stores the count value in the register corresponding to the area E 12 . Therefore, a value of the register becomes a sum of count values of pixels which form the first line within the area E 12 . 
     Similarly, when the main scanning counting unit  315  counts one line, or, in other words, what corresponds to X×n millimeters in the main scanning direction, the sub-scanning counting unit  316  counts the number of lines counted in the sub-scanning direction. In the case, the number of lines is 1. Thus, here, into the register corresponding to areas E 11  to E 1   n  is stored a sum of count values of pixels on the first line of the respective areas E 11  to areas E 1   n.    
     When one line count is completed, the main scanning counting unit  315  resumes counting from a pixel on the left end of the following line. The main scanning counting unit  315  starts counting from a pixel on the left end of the second line, and performs the same process thereon as on the first line. 
     In the present embodiment, when the sub-scanning counting unit  316  finishes counting the number of lines corresponding to Y millimeters in the sub-scanning direction, pixels within respective regions of X millimeters×Y millimeters are counted for the areas E 11  to E 1   n . Here, into the register corresponding to the areas E 11  to E 1   n  is stored a cumulative value of count values of all pixels within the E 11  to areas E 1   n.    
     In the present embodiment, the same process is performed on areas E 21  and thereafter, and a cumulative value of count values of pixels of the respective areas E 11  to Emn is obtained. 
     In other words, the image region determining unit  310  according to the present embodiment obtains a cumulative value of pixel count values for each area when image data are divided into areas of X millimeters×Y millimeters. 
     The present embodiment may include the same number of registers as the number of areas included in the image data G. In this case, the number of registers is m×n. Moreover, in the present embodiment, the number of registers may be set to be n, which is the same as the number of areas provided in the main scanning direction. In this case, when counting to the area E 1   n  is finished, the CPU  300  may temporarily store, in the RAM  222 , etc., a value stored in n registers and erase the values stored in all of the registers. The number of registers in the present embodiment may be determined in accordance with a size of the area E and a width of image data (in other words, a width of a recording material). For example, the number of registers when the maximum width of recording materials which can be printed in the image forming apparatus  100  is set to W10 millimeters, for example, may be at least W10 millimeters/X millimeters. 
     As described below, the count value stored in the register of the present embodiment is used only for determining presence/absence of an image for each area. 
     Therefore, in the present embodiment, a size of each register may be at least two bits. 
     In the present embodiment, it is set such that X=Y=2 millimeters. In other words, in the present embodiment, the image data becomes a set of areas of 2 millimeters×2 millimeters. 
     In the present embodiment, the value of X may be set to be the same value as a width of the heating element  30 N with the narrowest width, in the main scanning direction, of the multiple heating elements  30 N, for example. 
     Moreover, the value of Y in the present embodiment may be set such that V&gt;Y/t 1  when the conveying speed of the recording material in the image forming apparatus  100  is set to be V and a heating response time of the heating element  30 N is set to be t. The heating response time is a time from when heating of the heating element  30 N is started to when a temperature of the fixing roller  129  reaches a predetermined temperature which has been pre-set for fixing toner onto the recording material. In this way, determining a value of Y causes the heating response time to be sufficiently short relative to a time that the recording material is conveyed to a fixing position, making it possible to cause the fixing roller  129  to reach a predetermined temperature at a time of fixing. 
     Below, with reference to  FIG. 6 , determination of presence/absence of an image by the image presence/absence determining unit  313  is explained.  FIG. 6  is a view for explaining determination by the image presence/absence determining unit. 
     The image presence/absence determining unit  313  according to the present embodiment determines presence/absence of an image within each area based on a value of a register in which a cumulative value of a count value of each area is stored by the pixel counting unit  312 . More specifically, the image presence/absence determining unit  313  determines that a corresponding area is a non-image region with an image being absent when the value of the register is 0. Moreover, the image presence/absence determining unit  313  determines that the corresponding area is an image region with the image being present when the value of the register is not 0. The non-image region is a region with an image (unfixed toner) being absent and in which heating for fixing is unnecessary. The image region is a region with the image (unfixed toner) being present and a region which is to be heated by the heating element  30 N. 
     While the area thereof is determined to be the non-image region when a sum of the count values is 0 in the present embodiment, the area may be determined to be the non-image region when the count value is less than or equal to a predetermined value which is pre-set, for example. 
     The heating position determining unit  314  according to the present embodiment determines the image region to be a heating position. In an example in  FIG. 6 , it is seen that areas E 25 , E 35 , E 36 , E 42 -E 46 , E 52 -E 57 , E 66 , E 67 , and E 77  are the image regions. Thus, the heating position determining unit  314  determines these image regions to be the heating position. When the heating position is determined, the heating element selecting unit  320  according to the present embodiment selects the heating element  30 N corresponding to the heating position and heats the image region to be heated by the selected heating element  30 N. 
     Next, temperature control of the fixing apparatus  128  at a time of image forming by the image forming apparatus  100  according to the present embodiment is explained. 
       FIG. 7  is a diagram for explaining temperature control of a fixing apparatus at the time of image forming. 
     The fixing control unit  350  of the image forming apparatus  100  according to the present embodiment pre-sets three temperature regions by the heating element driving unit  330  to perform temperature control when performing fixing by the fixing apparatus  128 . The three temperature regions are a base temperature region, a paper temperature region, and a fixing temperature region. The base temperature region is a temperature region which is less than or equal to a base temperature H 1 . A temperature of the heating element  200  including multiple heating elements  30 N becomes a temperature within the base temperature region when the image forming apparatus  100  does not perform an image forming operation. In the present embodiment, a temperature sensor which detects a temperature of the heating element  200  is provided, which temperature is detected by a heating element temperature monitoring function provided in the image forming apparatus  100 . 
     A paper temperature region is a region of a temperature which is higher than the base temperature H 1  and less than or equal to a paper temperature H 2 . In the present embodiment, when the image forming apparatus  100  receives a printing request, a temperature of the heating element  200  is increased up to within the paper temperature region, and the heating element  200  is heated such that the temperature of the heating element  200  reaches the paper temperature H 2  when the recording material is detected. 
     The fixing temperature region is a temperature region which is higher than the paper temperature H 2 . In the present embodiment, when fixing is started in image forming, only the heating element  30 N selected as what is to be heated is heated out of the multiple heating elements  30 N included in the heating element  200  is heated to reach the fixing temperature H 3 . 
     In other words, in the present embodiment, the multiple heating elements  30 N included in the heating element  200  are heated to the paper temperature H 2 . Then, when the fixing is started, only the selected heating element  30 N is further heated to reach the fixing temperature H 3 . 
       FIG. 7 , in (A), shows an example of an area, while  FIG. 7 , in (B), shows an example of a temperature of the heating element  200  and a driving signal which heats the heating element  200 . 
     In the example in  FIG. 7 , areas E 2  to E 5  and areas E 7  to E 9  are image regions. Thus, the heating elements  30 N which heat the areas E 2  to E 5  and the areas E 7  to E 9  are heated to the fixing temperature H 3 . The other areas (areas E 1  and E 6 ) are non-image regions. Thus, the heating element  30 N corresponding to areas E 1  and E 6  reaches a temperature which is less than or equal to the paper temperature H 2 . 
     Next, an operation of the image forming apparatus  100  of the present embodiment is explained with reference to  FIG. 8 .  FIG. 8  is a flowchart which explains an operation of the image forming apparatus. 
     When the image forming apparatus  100  of the present embodiment accepts a printing request (step S 801 ), the fixing control process, a recording material detection process, and a temperature control process are performed in parallel. The fixing control process is executed by the fixing control unit  350  of the CPU  300  and the controller control unit  210 . The temperature control process is executed by the fixing control unit  350  of the CPU  300 . The recording material detection process is executed by the electric equipment control unit  223 . 
     First, a recording material detection process is explained. 
     In the image forming apparatus  100  in the present embodiment, the electric equipment control unit  223  starts conveying the recording material (step S 802 ). Next, the electric equipment control unit  223  determines whether the recording material reached the fixing apparatus  128  (step S 803 ). In the present embodiment, an arrival detecting sensor which detects an arrival of the recording material is provided in the fixing apparatus  128 , for example, so that the arrival of the recording material to the fixing apparatus  128  may be detected by the arrival detecting sensor. In step S 803 , when the recording material reaches the fixing apparatus  128 , the electric equipment control unit  223  outputs the recording material detecting signal to the CPU  300  (step S 804 ). When the recording material is detected, the fixing control unit  350  in the CPU  300  proceeds to the below-described step S 808 . 
     Moreover, when the recording material is detected, the electric equipment control unit  223  determines whether the recording material passed through the fixing apparatus  128  (step S 805 ). In the present embodiment, a passing detecting sensor which detects whether the recording material passed through the fixing apparatus  128  may be provided, for example, so that the passing of the recording material from the fixing apparatus  128  may be detected by the passing detecting sensor. When the recording material passes through the fixing apparatus  128  in step S 805 , the electric equipment control unit  223  determines presence/absence of the next printing request (step S 806 ). When the next printing request is present in step S 806 , the process proceeds to the below-described step S 810 . When the next printing request is absent in step S 806 , the process proceeds to the below-described step S 811 . 
     Next, the temperature control process is explained. 
     When the printing request is accepted, the fixing control unit  350  according to the present embodiment heats the heating element  200  by the heating element driving unit  330  to the base temperature H 1  (step S 807 ). Next, as the printing request has been accepted, the fixing control unit  350  further heats the heating element  200  by the heating element driving unit  330  to the paper temperature H 2  (step S 808 ). 
     Next, the fixing control unit  350  heats the heating element  30 N selected in the below-described step S 817  to the fixing temperature H 3  (step S 809 ). When the heating element  30 N reaches the fixing temperature H 3 , un-fixed toner is fixed to the recording material. 
     Next, the fixing control unit  350  maintains the temperature of the heating element  200  to the base temperature H 1  when the next printing request is present (step S 810 ). Moreover, when the next printing request is absent, the fixing control unit  350  stops heating of the heating element  200  and stops fixing (step S) ( 811 ). 
     Next, the fixing control process is explained. 
     The image forming apparatus  100  according to the present embodiment reads, by the controller control unit  210 , image data (step S 812 ). Next, the controller control unit  210  performs image processing on image data read by the image processing unit  214  (step S 813 ). Image processing by the image processing unit  214  is image processing required for outputting image data from the printer unit  120 . 
     Next, the controller control unit  210  transmits image-processed image data to the CPU  300  (step S 814 ). Next, in the fixing control unit  350  of the CPU  300 , the image region determining unit  310  counts pixels of the image data received from the controller control unit  310  and determines the image data to be a set of predetermined areas (step S 815 ). In other words, the image region determining unit  310  according to the present embodiment divides the image data into image data of the predetermined areas. A method of counting the pixels is as described above. 
     Next, the image region determining unit  310  determines, for all the areas in the image data, whether it is an image region or a non-image region (step S 816 ). 
     Next, the fixing control unit  350  allocates the image region into the multiple heating elements  30 N and selects the heating element  30 N to which the image region is allocated (step S 817 ) and proceeds to step S 809 . Details of the process in step S 817  are described below. 
     Below, with reference to  FIG. 9 , details of processing of the heating element selecting unit  320  of the present embodiment are explained.  FIG. 9  is a flowchart for explaining a process of a heating element selecting unit. Processing in  FIG. 9  shows details of processing in step S 817  in  FIG. 8 . 
     The heating element selecting unit  320  according to the present embodiment detects a width of the recording material (step S 901 ). The width of the recording material may be detected by an arrival detecting sensor, etc., which is provided in the fixing apparatus  128  when the recording material arrives at the fixing apparatus  128 , for example. 
     Next, the heating element selecting unit  320  selects the heating element  30 N for use in accordance with the width of the recording material (step S 902 ). More specifically, when the recording material is arranged at the center portion of the heating element  200  and the recording material corresponding to both end portions of the heating element  200  is not present, for example, the heating element  30 N for which corresponding recording material is absent is not used. For example, in the heating element  200  as shown in  FIGS. 2A and 2B , when a recording material is not present at a position corresponding to the heating element  301  and the heating element  30 N, the heating element selecting unit  320  selects, as a heating element to be used, a heating element other than the heating element  301  and the heating element  30 N. 
     Next, the heating element selecting unit  320  determines whether the heating element  30 N which is positioned at an end portion of the recording material is used (step S 903 ). For example, images may be concentrated at a center portion of the recording material, so that images at the end portion of the recording material are absent. In this case, it is not necessary to turn on the heating element  30 N which is positioned at the end portion of the recording material. In the present embodiment, it may be predetermined, by setting, as to whether the heating element  30 N which is positioned at the end portion of the recording material is used. 
     For example, for the setting of using the heating element  30 N which is positioned at the end portion of the recording material, the heating element selecting unit  320  selects all heating elements  30 N selected in step S 902 . Moreover, for the setting of not using the heating element  30 N which is positioned at the end portion of the recording material, the heating element selecting unit  320  does not select the applicable heating element  30 N. 
     Next, the heating element selecting unit  320  obtains heating element information  22  (see  FIG. 3 ) from the ROM  222 . The heating element information  22  according to the present embodiment, which is information on the heating element  200 , more specifically includes a temperature decrease rate due to rotating of a fixing belt  138 , a temperature increase rate, arrangement and a width of the respective multiple heating elements  320 N. 
     Next, the heating element selecting unit  320  allocates an area of image data to the heating element  30 N selected as what is to be used in steps S 902  and  5903  with reference to the heating element information  22  of the heating element  30 N (step S 905 ). In the present embodiment, when the area is allocated to the heating element  30 N, a width and arrangement of the heating element  30 N mainly included in the heating element information  22  are referred to. 
     Below, with reference to  FIG. 10 , allocation of the area of the image data to the heating element  30 N is described with reference to  FIG. 10 .  FIG. 10  is a diagram which explains allocation of the areas of the image data to the heating element. 
       FIG. 10  shows an example in which, in the heating element  200 , the heating elements  301  to  307  are selected as heating elements to be used. Moreover, an example is shown in which areas E 1  to E 21  are allocated to the heating element  200 . 
     The heating element selecting unit  320  according to the present embodiment determines, from an address of a register in which a count value of the area E 1  is stored, an area of which position in the main scanning and sub-scanning directions the area E 1  is in the image data. Then, the heating element selecting unit  320  determines which heating element  30 N is caused to heat the area E 1  from the position of the area E 1 . 
     For example, the heating element located at a position corresponding to the area E 1  is the heating element  301 . Therefore, the heating element selecting unit  320  allocates the area E 1  to the heating element  301 . Next, the heating element selecting unit  320  determines whether a total width We 1  of the areas E 1  and E 2  amounts to less than or equal to a width W 1  of the heating element  301 . Then, if the total width We 1 &lt;=the width W 1 , the heating element selecting unit  320  also allocates the area E 2  to the heating element  301 . 
     As described above, the heating element selecting unit  320  allocates an area to individual heating elements  30 N based on a width in a main scanning direction of the area and the width WN of the heating element  30 N. 
     For example, a width We 2  in the main scanning direction of areas E 3  and E 4  are less than or equal to a width W 2  of the heating element  302 . Therefore, the heating element selecting unit  320  according to the present embodiment allocates the areas E 3  and E 4  to the heating element  302 . Similarly, the heating element selecting unit  320  allocates areas E 5  to E 7  to the heating element  303  and areas E 8  to E 14  to the heating element  304 . Moreover, the heating element selecting unit  320  allocates areas E 15  to E 17  to the heating element  305 , areas E 18  and E 19  to the heating element  306 , and areas E 20  and E 21  to the heating element  307 . 
     As described above, the heating element selecting unit  320  according to the present embodiment allocates, to the heating element  30 N, all areas included in the image data. Next, the heating element selecting unit  320  determines whether turning on/off of all the heating elements  30 N have been determined (step S 906 ). “Turning on the heating element  30 N” here means that the heating element  30 N heated to the paper temperature H 2  is further heated to the fixing temperature H 3 . Moreover, “turning off the heating element  30 N” means maintaining the heating element  30 N at the paper temperature H 2  without heating it to the fixing temperature H 3 . 
     If turning on/off of the heating element  30 N is not yet determined, the fixing control unit  350  proceeds to the next step S 907 . The heating element selecting unit  320  determines whether an image region is present in an area allocated to the heating element  30 N (step S 907 ). 
     In step S 907 , if the image region is included in the area allocated, the heating body selecting unit  320  selects the heating element  30 N as a heating element to be turned on (step S 908 ) and returns to step S 906 . Moreover, if the image region is not included in the area allocated in step S 907 , the heating element selecting unit  320  sets the heating element  30 N as a heating element, leaving it off (step S 909 ) and returns to step S 906 . 
     In step S 906 , when on/off of all the heating elements  30 N has been determined, it proceeds to a process of step S 809  in  FIG. 8 . 
     Below, with reference to  FIG. 10 , determining on/off of the heating element  30 N is described. In  FIG. 10 , areas allocated to the heating element  301  are areas E 1  and E 2 . In an example in  FIG. 10 , no images are present in the area E 1 , so that the count value is 0. Therefore, the area E 1  is a non-image region. Moreover, the area E 2  includes images and the count value is 1. Therefore, the area E 2  is an image region. Therefore, in an example in  FIG. 10 , it is seen that, in an area allocated to the heating element  301 , an area in which the count value is not 0, or, in other words, an image region is included. Therefore, in the present embodiment, the heating element  301  is turned on. 
     Similarly, areas allocated to the heating element  302  are the areas E 3  and E 4 . The count values of the areas E 3  and E 4  are respectively 0. In other words, in the area allocated to the heating element  302 , no image region is present. Therefore, the heating element selecting unit  320  according to the present embodiment turns off the heating element  302 . 
     Similarly, in the example in  FIG. 10 , heating elements  303 ,  304 ,  305 , and  306  are turned on, while the heating element  307  is turned off. 
     As described above, in the present embodiment, only the heating element  30 N to which is allocated the image region in which the image is present is heated to the temperature H 3 . Therefore, according to the present embodiment, toner may be fixed efficiently. Moreover, in the present embodiment, image data read in are considered a set for a predetermined area, and fixing control is performed based on the count value of a pixel for each area, making it possible to reduce an amount of data handled at the time of fixing control. 
     While all areas are first allocated to the heating element  30 N first and then presence/absence of the images are determined in the areas in  FIG. 9 , it is not limited thereto. For example, presence/absence of images in each area may be determined first, allocating only areas in which an image is present. 
     While widths of the respective heating elements  30 N are described as being different in  FIG. 10 , it is not limited thereto. For example, the heating elements  30 N may all be of the same size or a width of an area may be the same as a width of the heating element  30 N. 
       FIGS. 11A and 11B  are diagrams showing examples of allocation of an area to the heating element when a width of the area is the same as a width of the heating element.  FIG. 11A  is a first example of allocation and  FIG. 11B  is a second example of allocation. 
     In  FIGS. 11A and 11B , areas E 21 -E 32  are allocated to the heating elements  301 - 30 N. In examples in  FIGS. 11A and 11B , one area is allocated to one heating element. 
     In the example in  FIG. 11A , of the areas E 21 -E 32 , areas which are image regions are the areas E 22 , and E 26 -E 31 . Therefore, the heating elements  30 N to which the areas E 22  and E 26 -E 31  are allocated are turned on. 
     In the example in  FIG. 11B , of the areas E 21 -E 32 , areas which are image regions are the areas E 22 -E 28 , E 30 , and E 31 . Therefore, the heating elements  30 N to which the areas E 22 -E 28 , E 30 , and E 31  are allocated are turned on. 
     As described above, in the present embodiment, image data are considered as a set of predetermined areas and each area is allocated to the multiple heating elements  30 N. Then, in the present embodiment, only the heating elements  30 N to which an image region is included in the area allocated is heated to the fixing temperature H 3 , fixing unfixed toner. 
     Moreover, in the present embodiment, image data are divided into predetermined areas, so that data handled in fixing control becomes a count value for each area. Therefore, in the present embodiment, relative to a case in which written control data based on image data are used in fixing control as they are, an amount of data handled at the time of fixing control may be reduced significantly. Moreover, in the present embodiment, only heating elements  30 N to which an area of an image region is allocated are heated to a fixing temperature. Therefore, the present embodiment makes it possible to reduce power related to fixing and to therefore fix toner efficiently. 
     Moreover, the image data is grasped as a set of predetermined areas, so that each area is allocated to the heating element. Therefore, in the present embodiment, an area may be allocated to a heating element if the heating element information  22  is stored in the ROM  222  even when a shape or the number of heating elements changes. Therefore, the present embodiment may be applied regardless of a shape or configuration of the heating body, making it possible to enhance generality. 
     While explanations of the present invention may be provided based on respective embodiments, the present invention is not so limited to requirements shown for the above described embodiments. These matters may be changed without compromising the spirit of the present invention, so that they may be appropriately determined according to the applicable embodiments thereof.