Patent Publication Number: US-2023152741-A1

Title: Image forming apparatus and method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-185865, filed on Nov. 15, 2021, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to an image forming apparatus and a method. 
     BACKGROUND 
     In the related art, an image forming apparatus includes various motors (driving units), in which rollers that rotate with driving forces of the motors are disposed. For example, a fixing unit includes a heating roller in which a fixing heater is built, a pressurization roller that is pressed against the heating roller, and a fixing motor that rotates the heating roller and the pressurization roller. The fixing unit melts and fixes toner on a sheet to the sheet while the sheet is passing through a gap between the heating roller and the pressurization roller. 
     In addition, in the image forming apparatus, a technique of displaying an error or stopping the operation if an abnormality occurs in each of the rollers, the fixing motor, or the like is also known. In addition, an abnormality or a breakdown around various motors can be estimated by monitoring current values of current signals of the various motors. 
     However, in the related art, there may be a case where an abnormality relating to a signal line of a current signal of a driving unit cannot be easily determined such that an abnormality or a breakdown around a motor cannot be estimated. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an appearance diagram illustrating an overall configuration example of an image forming apparatus  100  according to an embodiment; 
         FIG.  2    is a diagram illustrating an example of an internal configuration of the image forming apparatus  100 ; 
         FIG.  3    is a diagram illustrating an example of a hardware configuration of the image forming apparatus  100 ; 
         FIG.  4    is a diagram illustrating an example of a functional configuration of a control unit  300 ; 
         FIG.  5    is a diagram illustrating an example of an abnormality determination process relating to a fixing unit  40  that is executed by the image forming apparatus  100 ; 
         FIG.  6    is a diagram illustrating a notification example of a rotation abnormality relating to the fixing unit  40  that is displayed by a display  110 ; and 
         FIG.  7    is a diagram illustrating a notification example of a signal abnormality relating to the fixing unit  40  that is displayed by the display  110 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments provide an image forming apparatus and a method in which estimation failure of an abnormality or a breakdown around a driving unit can be reduced. 
     In general, according to one embodiment, an image forming apparatus includes a driving unit, a first determination unit, a second determination unit, and an output unit. The first determination unit is configured to determine whether or not a rotation abnormality relating to rotation of the driving unit occurs. The second determination unit is configured to determine whether or not a signal abnormality relating to a signal line of a current signal of the driving unit occurs based on a current value of the current signal after the first determination unit determines whether or not the rotation abnormality occurs. The output unit is configured to output a determination result of the second determination unit. 
     Hereinafter, an image forming apparatus and a method according to an embodiment will be described with reference to the drawings. In the following description, components having the same or equivalent function are represented by the same reference numeral. In addition, repeated description of configurations will not be made in some cases. 
     First, an overall configuration of an image forming apparatus  100  will be described using  FIG.  1   . 
       FIG.  1    is an appearance diagram illustrating an overall configuration example of the image forming apparatus  100  according to the embodiment. The image forming apparatus  100  is, for example, a multi-function peripheral. The image forming apparatus  100  includes a display  110 , a control panel  120 , a printer  130 , a sheet accommodation unit  140 , and an image reading unit  150 . 
     The display  110  is, for example, a touch panel type liquid crystal display. The display  110  displays various information. In addition, the display  110  receives the operation of a user. 
     The control panel  120  includes various operation keys such as numeric keypad or a start key. The control panel  120  receives various input operations from the user. In addition, the control panel  120  outputs operation signals corresponding to the various input operations received from the user to a control unit. 
     The printer  130  executes a series of printing operations using various information output from the display  110 , the control panel  120 , the image reading unit  150 , and the like. The series of printing operations include an operation of inputting image information, an operation of forming an image, an operation of transferring the formed image to a sheet, and an operation of conveying the sheet. 
     The sheet accommodation unit  140  includes a plurality of sheet cassettes. Each of the sheet cassettes accommodates a sheet. The sheet is mainly typical copy paper but may also be, for example, a photographic sheet, a label sheet, or a polyester film sheet. 
     The image reading unit  150  includes an automatic document feeder device and a scanner device. The automatic document feeder device feeds a document placed on a document tray to the scanner device. The scanner device optically scans the document on the document glass tray and focuses reflected light from the document on a light receiving surface of a charge coupled device (CCD) sensor. As a result, the scanner device reads a document image on the document glass tray. The image reading unit  150  generates image information (image data) using the read result read by the scanner device. 
       FIG.  2    is a diagram illustrating an example of an internal configuration of the image forming apparatus  100 . As illustrated in  FIG.  2   , the image forming apparatus  100  (printer  130 ) includes four image forming units  20   a  to  20   d  in parallel. The image forming apparatus  100  is a quadruple-tandem type image forming apparatus. The image forming apparatus  100  includes an image processing unit  10 , an image forming unit  20  ( 20   a  to  20   d ), an intermediate transfer unit  30 , a fixing unit  40 , and a sheet conveying unit  50 . 
     The image processing unit  10  inputs image information. The input image information is image information generated by the image reading unit  150  or image information transmitted from another device. The image processing unit  10  executes digital image processing of processing the input image information in accordance with an initial setting or a user setting. For example, the digital image processing includes gradation correction based on gradation correction data. In addition, the digital image processing includes, in addition to the gradation correction, various correction processes such as color correction or shading correction and other processes such as compression on the image data. 
     Next, the image forming unit  20  (image forming units  20   a  to  20   d ) will be described. The image forming unit  20  includes the image forming unit  20   a  corresponding to yellow (Y), the image forming unit  20   b  corresponding to magenta (M), the image forming unit  20   c  corresponding to cyan (C), and the image forming unit  20   d  corresponding to black (K). The image forming units  20   a  to  20   d  include photoconductive drums  21   a  to  21   d,  charging units  22   a  to  22   d,  an exposure unit  23 , developing units  24   a  to  24   d,  toner cartridges  25   a  to  25   d,  and a drum cleaning device (not illustrated). In the following description, a to d of the reference numerals are omitted. 
     The photoconductive drum  21  is, for example, a charged organic photoconductor (OPC) in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially stacked on a circumferential surface of an aluminum conductive cylindrical body. The photoconductive drum  21  is photoconductive. 
     The charging unit  22  causes corona discharge to occur. The charging unit  22  uniformly charges a surface of the photoconductive drum  21 . 
     The exposure unit  23  is, for example, a semiconductor laser. The exposure unit  23  irradiates the photoconductive drum  21  with laser light corresponding to images of the color components. If the photoconductive drum  21  is irradiated with the laser light by the exposure unit  23 , a potential of a region irradiated with the laser light in the region of the surface of the photoconductive drum  21  changes. Due to this change in potential (potential difference), an electrostatic latent image is formed on the surface of the photoconductive drum  21 . 
     The developing unit  24  contains a developer. The developing unit  24  attaches toners of the color components to the surface of the photoconductive drum  21 . As a result, a toner image is formed on the surface of the photoconductive drum  21 . That is, the electrostatic latent image formed on the surface of the photoconductive drum  21  is visualized. 
     Here, the developer will be described. As the developer, for example, a two-component developer is used. The two-component developer contains non-magnetic toner and a carrier. As the carrier, for example, iron powder or polymer ferrite particles having a particle size of several tens of micrometers are used. The carrier is mixed with the toner in the developing unit  24  and is triboelectrically charged such that charge (for example, negative charge) is applied to the toner. In addition, the carrier conveys the toner to the electrostatic latent image using a magnetic force. 
     In addition, the drum cleaning device (not illustrated) includes a cleaning blade that comes into contact with the surface of the photoconductive drum  21 . The cleaning blade removes residual toner remaining on the surface of the photoconductive drum  21  after the primary transfer. The removed residual toner is collected by an accommodation unit in the drum cleaning device. 
     Next, the intermediate transfer unit  30  will be described. The intermediate transfer unit  30  includes an intermediate transfer medium  31 , a primary transfer roller  32 , a plurality of support rollers  33 , a secondary transfer roller  34 , and a belt cleaning device  35 . 
     The intermediate transfer medium  31  is, for example, an endless belt (transfer belt). The intermediate transfer medium  31  is a belt not having conductivity and elasticity. Specifically, the intermediate transfer medium  31  is, for example, a polyimide belt. The intermediate transfer medium  31  may have conductivity and elasticity. 
     The support rollers  33   a  to  33   c  support the intermediate transfer medium  31  such that a tensile force is applied to the intermediate transfer medium  31 . As a result, the intermediate transfer medium  31  is formed in a loop shape. Among the plurality of support rollers  33   a  to  33   c,  one roller (for example, the support rollers  33   a ) is a driving roller. The rollers other than the driving roller are driven rollers. By driving and rotating the driving roller, the intermediate transfer medium  31  moves in an A direction of the drawing at a predetermined speed at a predetermined period. 
     Here, the direction in which the intermediate transfer medium  31  moves can be defined as an upstream direction and a downstream direction. Specifically, in the direction in which the intermediate transfer medium  31  moves, the image forming unit  20   a  can be defined as the most upstream side, and the belt cleaning device  35  can be defined as the most downstream side. 
     The primary transfer roller  32  is disposed to face the photoconductive drum  21  through the intermediate transfer medium  31 . Specifically, the primary transfer roller  32  is disposed such that a pressure is applied to the photoconductive drum  21  in a state where the intermediate transfer medium  31  is interposed therebetween. As a result, the primary transfer roller  32  and the photoconductive drum  21  form a primary transfer unit that nips the intermediate transfer medium  31 . 
     If the intermediate transfer medium  31  passes through the primary transfer unit, the toner image formed on the photoconductive drum  21  is transferred to the intermediate transfer medium  31 . If the intermediate transfer medium  31  passes through the primary transfer unit, a primary transfer bias is applied to the primary transfer roller  32 . Specifically, charge having a polarity (positive polarity) opposite to that of the toner is applied to the primary transfer roller  32 . As a result, the toner image formed on the photoconductive drum  21  is electrostatically transferred to the intermediate transfer medium  31 . 
     The secondary transfer roller  34  is disposed to face the support rollers  33   a  through the intermediate transfer medium  31 . Specifically, the secondary transfer roller  34  is disposed such that a pressure is applied to the support rollers  33   a  in a state where the intermediate transfer medium  31  is interposed therebetween. As a result, the secondary transfer roller  34  and the support rollers  33   a  form a secondary transfer unit  38  that nips the intermediate transfer medium  31  and the sheet. 
     If the sheet passes through the secondary transfer unit  38 , the toner image formed on the intermediate transfer medium  31  is transferred to the sheet. If the sheet passes through the secondary transfer unit  38 , a secondary transfer bias is applied to the support rollers  33   a.  Specifically, charge having the same polarity (negative polarity) as that of the toner is applied to the support rollers  33   a.  As a result, the toner image on the intermediate transfer medium  31  is electrostatically transferred to the sheet. 
     The secondary transfer roller  34  and the support rollers  33   a  are configured to be separable from each other. As a result, if the sheet is clogged in the secondary transfer unit  38 , the user can remove the sheet. 
     The belt cleaning device  35  includes a cleaning blade that comes into contact with the surface of the intermediate transfer medium  31 . The cleaning blade removes residual toner remaining on the surface of the intermediate transfer medium  31  after the secondary transfer. The removed residual toner is collected by an accommodation unit in the belt cleaning device  35 . 
     The fixing unit  40  heats and pressurizes the sheet to which the toner image is transferred. The fixing unit is, for example, a roller type including: a heating roller that heats the sheet; and a pressurization roller that is pressed against the heating roller. As a result, the fixing unit  40  fixes the toner image to the sheet. A method of heating the sheet through a film-shaped member to fix the toner image to the sheet is also applicable to the fixing unit  40 . 
     Next, the sheet conveying unit  50  will be described. The sheet conveying unit  50  includes a paper feed unit  51 , a registration unit  52 , a first guide unit  53 , a second guide unit  54 , and a paper discharge unit  55 . 
     The paper feed unit  51  conveys the sheets accommodated in the sheet accommodation unit  140  one by one to the registration unit  52 . The registration unit  52  stops the sheet conveyed from the paper feed unit  51  and supplies the sheet to the secondary transfer unit  38  at a predetermined timing. The predetermined timing is a timing at which the toner image formed on the intermediate transfer medium  31  is secondarily transferred by the secondary transfer unit  38 . The first guide unit  53  restricts a conveying direction of the sheet supplied from the registration unit  52  to the secondary transfer unit  38 . 
     The secondary transfer unit  38  transfers the toner image to the sheet of which the conveying direction is restricted by the first guide unit  53 . Further, the secondary transfer unit  38  supplies the sheet to which the toner image is transferred to the fixing unit  40 . 
     The second guide unit  54  restricts the conveying direction of the sheet supplied from the secondary transfer unit  38  to the fixing unit  40 . The fixing unit  40  heats and pressurizes the sheet of which the conveying direction is restricted by the second guide unit  54 , and supplies the sheet to the paper discharge unit  55 . The paper discharge unit  55  supplies the sheet to a discharge tray. 
     Next, a hardware configuration of the image forming apparatus  100  will be described using  FIG.  3   . 
       FIG.  3    is a diagram illustrating an example of the hardware configuration of the image forming apparatus  100 . As illustrated in  FIG.  3   , in addition to the above-described configurations, the image forming apparatus  100  includes a central processing unit (CPU)  201 , a memory  202 , a communication unit  203 , and a speaker  204 . The components can communicate with each other via a bus. 
     The CPU  201  is a central processing unit and controls the operation of the image forming apparatus  100  by loading and executing various programs stored in the memory  202 . The various programs include an abnormality determination program according to the embodiment. 
     The memory is a ROM, a RAM, a hard disk, or the like. The ROM is a read only memory, and stores not only programs but also various information used by the CPU. The RAM is a readable or writable memory, and stores various information. For example, the RAM stores information acquired from an external apparatus or information generated in various processes. The hard disk stores various information. 
     The communication unit  203  is an interface that transmits and receives information to and from another apparatus. 
     The speaker  204  outputs a voice. 
     Next, a functional configuration of the control unit  300  will be described using  FIG.  4   . 
       FIG.  4    is a diagram illustrating an example of the functional configuration of the control unit  300 . The control unit  300  includes a first determination unit  301 , an acquisition unit  302 , a second determination unit  303 , an output unit  304 , a driving control unit  305 , and a notification unit  306 . The units are implemented by the CPU  201 . That is, the function of each of the units is implemented by the CPU  201  executing a predetermined program stored in the memory. The process according to the embodiment is not necessarily executed by the CPU  201  executing the program. For example, the process according to the embodiment can also be executed using hardware (circuit unit; including circuitry) such as an LSI (large scale integration), an ASIC (application specific integrated circuit), a FPGA (field-programmable gate array), or a GPU (graphics processing unit), or can also be executed using software and hardware in combination. 
     Hereinafter, the fixing unit  40  as a target to be controlled by the control unit  300  will be described as an example. In  FIG.  4   , the fixing unit  40  includes a heating roller  40   a  and a pressurization roller  40   b.  A nip region is formed between the heating roller  40   a  and the pressurization roller  40   b.  While the sheet St is passing through the nip region, the toner on the sheet St melts and is fixed to the sheet. The heating roller  40   a  and the pressurization roller  40   b  rotate with a driving force of a fixing motor  310 . The fixing motor  310  is an example of the driving unit. 
     The fixing motor  310  only needs to drive one of the heating roller  40   a  or the pressurization roller  40   b.  The other (non-driven) one of the heating roller  40   a  or the pressurization roller  40   b  is driven to rotate by the rotation of the one of the heating roller  40   a  or the pressurization roller  40   b.  During printing, the heating roller  40   a  and the pressurization roller  40   b  rotate with the driving force of the fixing motor  310 . Therefore, a load on the fixing motor  310  increases. 
     The first determination unit  301  determines whether or not a rotation abnormality relating to the rotation of the fixing motor  310  occurs. Specifically, the first determination unit  301  acquires a signal representing the rotation value of the fixing motor  310  from a rotation detection unit  311 . The rotation detection unit  311  is, for example, a sensor that detects an operation of an actuator that rotates together with the rotation of the heating roller  40   a  and the pressurization roller  40   b.  If the heating roller  40   a  and the pressurization roller  40   b  are rotated, the first determination unit  301  determines that the fixing motor  310  is normal based on the signal. If the heating roller  40   a  and the pressurization roller  40   b  are not rotated, the first determination unit  301  determines that the fixing motor  310  is abnormal (rotation abnormality) based on the signal. 
     The acquisition unit  302  acquires a current value of a current signal of the fixing motor  310  after the first determination unit  301  determines whether or not the rotation abnormality occurs. The acquisition unit  302  acquires the current value through a signal line  320 . The current signal is, for example, an analog signal. The current value is, for example, a current value acquired if the first determination unit  301  determines whether or not the rotation abnormality occurs. The current value represents a load on the fixing motor  310  and is used for monitoring to estimate a breakdown. For example, if a sheet conveyance belt deteriorates such that the load increases or if the belt is cut such that the load decreases, the current value varies depending on the change in load. A breakdown is estimated based on the determination using not only the current value of the fixing motor  310  but also various information such as a PM counter (for example, a driving time of a roller or the number of sheets printed) or a jam (clogging) occurrence state. 
     The second determination unit  303  determines whether or not a signal abnormality relating to the signal line  320  of the current signal occurs based on the current value acquired by the acquisition unit  302 . Specifically, the signal abnormality is disconnection of the signal line  320  of a harness or disconnection or short-circuit of the signal line  320  on a substrate. If the current value is appropriate (in a first predetermined range), the second determination unit  303  determines that the signal abnormality does not occur. On the other hand, if the current value is not appropriate, the second determination unit  303  determines that the signal abnormality occurs. 
     Whether the signal abnormality is short-circuit or disconnection can be determined depending on whether the signal abnormality is an abnormality where the current value exceeds an upper limit value or an abnormality where the current value falls below a lower limit value. For example, if the current value exceeds the upper limit value, the second determination unit  303  determines that the signal abnormality is short-circuit, and if the current value falls below the lower limit value, the second determination unit  303  determines that the signal abnormality is disconnection. 
     The output unit  304  outputs the determination result of the second determination unit  303 . The output unit  304  causes the display  110  to display the determination result of the second determination unit  303  in accordance with the determination result of the second determination unit  303 . For example, if the second determination unit  303  determines that the signal abnormality does not occur, the output unit  304  causes the display  110  not to display the determination result. On the other hand, if the second determination unit  303  determines that the signal abnormality occurs, the output unit  304  causes the display  110  to display the determination result. 
     In addition, the output unit  304  transmits the determination result of the second determination unit  303  to a terminal apparatus of a support staff via the communication unit  203  in accordance with the determination result of the second determination unit  303 . The support staff is a staff who goes to an installation location of the image forming apparatus  100  to execute maintenance or the like. For example, if the second determination unit  303  determines that the signal abnormality does not occur, the output unit  304  does not transmit the determination result. On the other hand, if the second determination unit  303  determines that the signal abnormality occurs, the output unit  304  transmits the determination result. 
     If the first determination unit  301  determines that the rotation abnormality does not occur, the second determination unit  303  determines whether or not the signal abnormality occurs. However, even if the first determination unit  301  determines that the rotation abnormality occurs, the second determination unit  303  may determine whether or not the signal abnormality occurs. If the first determination unit  301  determines that the rotation abnormality occurs but the second determination unit  303  determines that the signal abnormality does not occur, the image forming apparatus  100  can estimate that an abnormality may occur in the rotation detection unit  311 . 
     If the second determination unit  303  determines that the signal abnormality occurs, the driving control unit  305  sets the operation of the fixing motor  310  to be stoppable. The stop of the operation of the fixing motor  310  is the stop of the operation of the image forming apparatus  100 . In this case, even if the second determination unit  303  determines that the signal abnormality occurs, the image forming apparatus  100  cannot be stopped instantaneously. Therefore, even if the second determination unit  303  determines that the signal abnormality occurs, the driving control unit  305  may be configured not to stop the operation of the fixing motor  310  (the operation of the image forming apparatus  100 ). 
     In addition, a threshold (second predetermined range) for stopping the operation of the fixing motor  310  may be set. The second predetermined range is a range that is wider than the first predetermined range. That is, even if the second determination unit  303  determines that the signal abnormality occurs, the driving control unit  305  may be configured not to stop the operation of the fixing motor  310  if the current value is in the second predetermined range and configured to stop the operation of the fixing motor  310  if the current value is not in the second predetermined range. 
     In the embodiment, if the second determination unit  303  determines that the signal abnormality occurs, the driving control unit  305  may be configured to stop the operation of the fixing motor  310  depending on selection of the user. If the first determination unit  301  determines that the rotation abnormality occurs, the image forming apparatus  100  cannot be used. Therefore, the driving control unit  305  is configured to stop the operation of the fixing motor  310  (the operation of the image forming apparatus  100 ) instantaneously. 
     The notification unit  306  gives notifications that are different between if the first determination unit  301  determines that the rotation abnormality occurs and if the second determination unit  303  determines that the signal abnormality occurs. If the first determination unit  301  determines that the rotation abnormality occurs, the notification unit  306  notifies that the rotation abnormality occurs. If the second determination unit  303  determines that the signal abnormality occurs, the notification unit  306  notifies that the signal abnormality occurs. The aspect of the notification may be a voice by the speaker  204  instead of or together with a display by the display  110 . 
     In addition, in the embodiment, if a power supply is powered, the determination of the first determination unit  301  on the rotation abnormality and the determination of the second determination unit  303  on the signal abnormality are executed. The time if the power supply is powered is in a warm-up state immediately after the power supply is powered. As a result, the same condition can be adopted for each determination of the abnormality. Therefore, the accuracy of the determinations can be improved. These determinations are not necessarily executed if the power supply is powered, and may be executed during warm-up after wake-up from a sleep mode. The warm-up is executed for about 10 to 20 seconds. 
     Next, an abnormality determination process relating to the fixing unit  40  that is executed by the image forming apparatus  100  will be described using  FIG.  5   . 
       FIG.  5    is a diagram illustrating an example of the abnormality determination process relating to the fixing unit  40  that is executed by the image forming apparatus  100 . As illustrated in  FIG.  5   , the image forming apparatus  100  (control unit  300 ) waits (ACT  501 : NO) until, for example, a power supply switch is pressed to start the image forming apparatus  100 . If the image forming apparatus  100  starts (ACT  501 : YES), the image forming apparatus  100  starts warm-up (ACT  502 ). 
     Next, the image forming apparatus  100  clears current signal normal information stored in the memory  202  in the determination of the current value of the fixing motor  310  during previous warm-up from the memory  202  (ACT  503 ). The image forming apparatus  100  determines whether or not the rotation abnormality of the fixing motor  310  is detected (ACT  504 ). If the rotation abnormality of the fixing motor  310  is detected (ACT  504 : YES), the image forming apparatus  100  notifies the rotation abnormality of the fixing motor  310  (ACT  505 ), and proceeds to ACT  511 . 
     If the rotation abnormality of the fixing motor  310  is not detected (ACT  504 : NO), the image forming apparatus  100  determines whether or not the current value of the fixing motor  310  is appropriate (in the predetermined range) (ACT  506 ). If the current value of the fixing motor  310  is not appropriate (ACT  506 : NO), the image forming apparatus  100  proceeds to ACT  508 . If the current value of the fixing motor  310  is appropriate (ACT  506 : YES), the image forming apparatus  100  stores the current signal normal information in the memory  202  (ACT  507 ). Next, the image forming apparatus  100  determines whether or not the warm-up ends (ACT  508 ). 
     If the warm-up does not end (ACT  508 : NO), the image forming apparatus  100  returns to ACT  504  and repeats the processes of ACT  504  to ACT  507 . Therefore, if the current value of the fixing motor  310  is an appropriate value even once, the current signal normal information is stored in the memory  202 . In other words, unless the current value of the fixing motor  310  is an appropriate value at all times, the current signal normal information is not stored in the memory  202 . However, the embodiment is not limited to this configuration, and if the current value of the fixing motor  310  is an appropriate value a predetermined number of times or more, the current signal normal information may be stored in the memory  202 . 
     If the warm-up ends (ACT  508 : YES), the image forming apparatus  100  determines whether or not the current signal normal information is stored in the memory  202  (ACT  509 ). If the current signal normal information is not stored in the memory  202  (ACT  509 : NO), the image forming apparatus  100  notifies the abnormality of the signal line  320  (ACT  510 ). The image forming apparatus  100  stops the operation (ACT  511 ) and ends the series of processes. During the notification in ACT  505  or ACT  510 , the image forming apparatus  100  transmits the content to a terminal apparatus of a support staff. As a result, the notification can urge the support staff to execute maintenance for the abnormality. 
     If the current signal normal information is stored in the memory  202  in ACT  509  (ACT  509 : YES), the image forming apparatus  100  starts a ready control (ACT  512 ) to prepare printing, and ends the series of processes. 
     Next, a notification example of the abnormality relating to the fixing unit  40  that is displayed by the display  110  will be described using  FIGS.  6  and  7   . 
       FIG.  6    is a diagram illustrating a notification example of the rotation abnormality relating to the fixing unit  40  that is displayed by the display  110 . In  FIG.  6   , a rotation abnormality notification screen  601  is a screen that is displayed if the rotation abnormality of the fixing motor  310  is detected. The rotation abnormality notification screen  601  includes a content that the fixing motor  310  is abnormal and a content that the operation of the image forming apparatus  100  is stopped. 
       FIG.  7    is a diagram illustrating a notification example of the signal abnormality relating to the fixing unit  40  that is displayed by the display  110 . In  FIG.  7   , a signal line abnormality notification screen  602  includes a content that the abnormality is detected in the signal line  320  of the fixing motor  310  and a confirmation button for confirming whether or not to stop the operation of the image forming apparatus  100 . The confirmation button includes a “YES” button for receiving the stop of the operation and a “NO” button for receiving the continuation of the operation. If the user presses the “YES” button, the operation of the image forming apparatus  100  stops. On the other hand, if the user presses the “NO” button, the operation of the image forming apparatus  100  continues. In this case, even if the operation of the image forming apparatus  100  continues, the image forming apparatus  100  may notify that maintenance is necessary at predetermined intervals. 
     As described above, in the image forming apparatus  100  according to the embodiment, after determining whether or not the rotation abnormality of the fixing motor  310  occurs, it is determined whether or not the signal abnormality relating to the signal line  320  occurs based on the current value of the current signal of the fixing motor  310 , and the determination result is output. As a result, while reducing erroneous determination caused by an inrush current, the abnormality (short-circuit or disconnection) of the signal line  320  of the current signal of the fixing motor  310  can be simply determined with high accuracy. Accordingly, estimation failure of an abnormality or a breakdown around the fixing motor  310  can be reduced with high efficiency. 
     In addition, in the image forming apparatus  100  according to the embodiment, if the determination is made that the rotation abnormality of the fixing motor  310  does not occur, it is determined whether or not the signal abnormality occurs. As a result, whether or not the abnormality of the signal line  320  occurs can be determined under the same condition that the rotation abnormality does not occur. Therefore, the determination can be made with higher accuracy. 
     In addition, in the image forming apparatus  100  according to the embodiment, the operation of the fixing motor  310  is set to be stoppable if the determination is made that the signal abnormality occurs. As a result, if the determination is made that the abnormality of the signal line  320  occurs, the use of the image forming apparatus  100  can be stopped. Accordingly, estimation failure of an abnormality or a breakdown around the fixing motor  310  can be reduced. 
     In addition, in the image forming apparatus  100  according to the embodiment, notifications that are different between if the determination is made that the rotation abnormality of the fixing motor  310  occurs and if the determination is made that the abnormality of the signal line  320  occurs are given. As a result, the user can grasp the content of the occurred abnormality. In addition, at a manufacturing stage, a manufacturing staff can grasp the content of the abnormality and can correct the abnormal portion quickly. 
     In addition, in the image forming apparatus  100  according to the embodiment, the determination on whether or not the rotation abnormality of the fixing motor  310  occurs and the determination on whether or not the signal abnormality relating to the signal line  320  occurs are executed if the power supply is powered. As a result, the same condition can be adopted for each determination of the abnormality. Therefore, whether or not the abnormality of the fixing motor  310  occurs and whether or not the signal abnormality occurs can be determined with higher accuracy. 
     In addition, the driving unit to be controlled by the image forming apparatus  100  according to the embodiment is the fixing motor  310  used in the fixing unit  40 . As a result, estimation failure of an abnormality or a breakdown around the fixing unit  40  can be reduced with high efficiency. 
     In the embodiment, the fixing unit  40  as a target to be controlled by the control unit  300  is described as an example. However, the target to be controlled by the control unit  300  is not limited to the fixing unit  40 . For example, any member or portion can be adopted as a target to be controlled by the control unit  300  as long as it is a portion where the current value of the current signal of the driving unit can be acquired after determining whether or not the rotation abnormality of a member that rotates with the rotation of the driving unit and the drive motor occurs. More specifically, for example, if the sheet conveying unit  50  is a target to be controlled, the control unit  300  may acquire the current value of the current signal of the drive motor to determine whether or not the signal abnormality occurs after determining whether or not the rotation abnormality of the driving roller that is rotated by the drive motor and the drive motor occurs. As a result, estimation failure of an abnormality or a breakdown around the drive motor can be reduced with high efficiency. 
     Each of the functions of the image forming apparatus  100  in the embodiment may be implemented by a computer. In this case, the function may be realized by recording a program for implementing this function in a computer-readable recording medium and causing a computer system to read the program recorded in the recording medium and to execute the read program. The definition of “computer system” described herein includes an OS and a hardware such as a peripheral. In addition, “computer-readable recording medium” refers to a storage device, for example, a portable medium such as a flexible disk, a magneto-optic disk, a ROM, or a CD-ROM or a hard disk built into a computer system. Further, “computer-readable recording medium” may also refer to a medium that dynamically stores a program for a short period of time like a communication line if a program is transmitted through a network such as the Internet or a communication line such as a telephone line or refer to a medium that stores a program for a certain period of time like a volatile memory in a computer system functioning as a server or a client. In addition, the program may implement some of the above-described functions or may implement the above-described function in combination with a program recorded in a computer system in advance. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms: furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such embodiments or modifications as would fall within the scope and spirit of the inventions.