Patent Publication Number: US-11644772-B2

Title: Image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2021-030768, filed on Feb. 26, 2021. The contents of this application are incorporated herein by reference in their entirety. 
     BACKGROUND 
     The present disclosure relates to an image forming apparatus. 
     There is a technique that copes with an excessive increase in temperature of a fixing device upon out of control of a heating body due to thermistor failure. 
     SUMMARY 
     An image forming apparatus according to an aspect of the present disclosure includes a fixing device. The fixing device includes a fixing belt, a heater, and a pressure roller. The fixing belt heats a toner image transferred to a sheet to fix the toner image to the sheet. The heater heats the fixing belt. The pressure roller rotates the fixing belt while in contact with the fixing belt. The image forming apparatus further includes a duration measuring section, a temperature measurement section, a temperature information output section, a temperature tendency computing section, a drive controller, and a pressure roller drive section. The duration measuring section measures a plurality of time durations. The temperature measuring section measures a temperature of the heater at each of the times or measure a temperature of the fixing belt at each of the times. The temperature information output section outputs heater temperature information based on the temperatures of the heater at the respective times or output fixing belt temperature information based on the temperatures of the fixing belt at the respective times. The temperature tendency computing section outputs temperature tendency information of the heater based on the heater temperature information or output temperature tendency information of the fixing belt based on the fixing belt temperature information. The drive controller outputs linear velocity information for controlling a linear velocity of the pressure roller based on the temperature tendency information of the heater or the temperature tendency information of the fixing belt. The pressure roller drive section drives the pressure roller based on the linear velocity information. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a diagram illustrating a multifunction peripheral including an image forming apparatus according to an embodiment of the present disclosure. 
         FIG.  2    is a block diagram of a configuration of the image forming apparatus according to the embodiment. 
         FIG.  3    is a cross-sectional view of a configuration of a fixing device included in the image forming apparatus according to the embodiment. 
         FIG.  4    is a block diagram of elements for temperature control in the fixing device. 
         FIGS.  5 A and  5 B  illustrate linear velocity control on a pressure roller based on temperature change of a heater after the fixing device stops working. 
         FIGS.  6 A and  6 B  illustrate linear velocity control on the pressure roller based on temperature change of the heater after a warmup start of the fixing device. 
         FIG.  7    is a flowchart depicting an example of temperature control in the fixing device. 
         FIG.  8    is a flowchart depicting another example of the temperature control in the fixing device. 
     
    
    
     DETAILED DESCRIPTION 
     The following describes an embodiment of the present disclosure with reference to the accompanying drawings. Note that elements that are the same or equivalent are indicated by the same reference signs in the drawings and description thereof is not repeated. In the drawings, an X axis, a Y axis, and a Z axis that are perpendicular to one another are indicated as appropriate. The Z axis is parallel to the vertical direction, and the X axis and the Y axis are parallel to a horizontal plane. 
     The Z-axis direction may be referred to as “sub-scanning direction” in the present embodiment. Also, the Y-axis direction may be referred to as “main scanning direction”. The X-axis direction may be referred to as “direction perpendicular to the main scanning direction and the sub-scanning direction”. 
     The configuration of a multifunction peripheral  1  will be described with reference to  FIG.  1   .  FIG.  1    is a diagram illustrating the multifunction peripheral  1  including a fixing device  16  according to the present embodiment. The configuration of an image forming apparatus  3  including the fixing device  16  in the present embodiment will be also described with reference to  FIG.  2   .  FIG.  2    is a block diagram of the configuration of the image forming apparatus  3  including the fixing device  16  in the present embodiment. 
     As illustrated in  FIG.  1   , the multifunction peripheral  1  includes a document reading device  2  and an image forming apparatus  3 . The multifunction peripheral  1  has functions of a scanner, a copier, a printer, and a facsimile machine, and an additional function, for example. 
     The document reading device  2  includes a document feed tray, a document feed section, a document conveyance section, a document reading section, an optical member, a document ejecting section, and a document exit tray, for example. 
     The image forming apparatus  3  includes a printer controller  10 , a printer drive section  11 , sheet trays  12 , sheet feed sections  13 , a sheet conveyance section  14 , an image forming section  15 , a fixing device  16 , a sheet ejecting section  17 , and a sheet exit tray  18 . 
     The printer controller  10  controls operation of each element of the image forming apparatus  3 . The printer controller  10  may function as a controller that controls operation of each element of the multifunction peripheral  1 . Specific examples of the printer controller  10  includes a central processing unit (CPU), a micro-processing unit (MPU), and an application specific integrated circuit (ASIC). 
     The printer drive section  11  drives each element of the image forming apparatus  3 . The printer drive section  11  may be a drive section that drives each element of the multifunction peripheral  1 . Specific examples of the printer drive section  11  include an electric motor, an electromagnetic solenoid, a hydraulic cylinder, and a pneumatic cylinder. 
     Sheets S are stacked on each sheet tray  12 . The sheets S each are an example of a recording medium. The sheet tray  12  may include a tray and a lifting member. The sheet feed sections  13  each picks up the sheets S stacked on the sheet tray  12  one at a time for feeding. Each of the sheet feed sections  13  is a pickup roller, for example. 
     The sheet conveyance section  14  conveys each sheet S fed from the sheet tray  12 . The sheet conveyance section  14  forms a conveyance path. The conveyance path extends from each sheet tray  12  as a starting point to the sheet ejecting section  17  via the image forming section  15  and the fixing device  16 . The sheet conveyance section  14  may include conveyance rollers and a registration roller along the conveyance path. 
     The conveyance rollers may be disposed along the conveyance path to convey the sheet S. The registration roller adjusts timing of conveyance of the sheet S to the image forming section  15 . The sheet conveyance section  14  conveys the sheet S from the sheet tray  12  to the sheet ejecting section  17  via the image forming section  15  and the fixing device  16 . 
     The image forming section  15  electrographically forms a non-illustrated toner image on the sheet S based on document image data. The document image data represents an image of a document G, for example. 
     The fixing device  16  applies heat and pressure to the toner image developed on the sheet S to fix the toner image to the sheet S. 
     The sheet ejecting section  17  ejects the sheet S out of the casing of the multifunction peripheral  1  (image forming apparatus  3 ). The sheet ejecting section  17  is an ejection roller, for example. 
     The sheets S ejected by the sheet ejecting section  17  are stacked on the sheet exit tray  18 . 
     The configuration of the fixing device  16  in the present embodiment will be described next in detail with reference to  FIG.  3   .  FIG.  3    is a cross-sectional view of the configuration of the fixing device  16  in the present embodiment. 
     As illustrated in  FIG.  3   , the fixing device  16  includes a fixing belt  30 , a pressure member  31 , a heater  32 , a heater holding member  33 , a frame stay metal plate  34 , a frame stay metal plate holder  35 , and a fixing belt holder  36 . 
     The fixing belt  30  heats the sheet S ( FIG.  1   ), to which the toner image formed in the image forming section  15  illustrated in  FIG.  1    has been transferred and which has been conveyed to the fixing device  16 , to fix the toner image to the sheet S. 
     The fixing belt  30  illustrated in  FIG.  3    is an endless belt. The fixing belt  30  has a substantially cylindrical shape. The fixing belt  30  is flexible. 
     The fixing belt  30  includes a plurality of layers. For example, the fixing belt  30  includes a polyimide layer containing polyimide, an elastic layer containing an elastic material such as silicone rubber, and a release layer. The release layer serves as an outermost layer formed on the outer circumferential surface of the polyimide layer. The release layer is a heat resistant film made from fluororesin, for example. 
     The pressure member  31  is rotationally driven while being pressed against (in contact with) the fixing belt  30  to rotationally drive the fixing belt  30 . The pressure member  31  has a substantially columnar shape, and is disposed opposite to the fixing belt  30 . The pressure member  31  is a pressure roller, for example. In the following, the pressure member  31  may be referred to as “pressure roller  31 ”. 
     The pressure roller  31  includes a columnar metal core, a cylindrical elastic layer, and a release layer. The elastic layer is formed on the metal core. The release layer is formed to cover the surface of the elastic layer. 
     The metal core is made from stainless steel or aluminum, for example. The elastic layer is elastic and is made from for example silicone rubber. The release layer is made from fluororesin, for example. 
     The heater  32  is connected to a non-illustrated power source and generates heat. The heater  32  heats the fixing belt  30 . The heater  32  is disposed opposite to the inner circumferential surface of the fixing belt  30 . 
     The heater  32  is a surface heater or a heater with a thin and narrow plate shape, for example. For example, the heater  32  is a ceramic heater and includes a ceramic substrate and a resistive heating element. The heater  32  has a thickness of 1 mm, for example. The heater  32  receives pressure from the pressure roller  31  via the fixing belt  30 . 
     As a result of the pressure roller  31  being pressed to the fixing belt  30 , a nip part N is formed at a contact part between the fixing belt  30  and the pressure roller  31 . As a result of the pressure roller  31  being pressed to the fixing belt  30 , the heater  32  is pressed against the inner circumferential surface of the fixing belt  30 . As such, the fixing belt  30  is heated by the heater  32  to fix the toner image formed on the sheet S ( FIG.  1   ) to the sheet S when the sheet S passes through the nip part N. 
     The heater holding member  33  guides the fixing belt  30  in a rotatable manner, and holds the heater  32  that heats the fixing belt  30 . 
     The frame stay metal plate  34  reinforces the heater holding member  33 . The frame stay metal plate  34  is a metal-made slender frame stay member. The frame stay metal plate  34  may have an angular U shape, a U shape, or a V shape. 
     The frame stay metal plate holder  35  holds the frame stay metal plate  34  so as to fix the frame stay metal plate  34  to the heater holding member  33 . 
     The fixing belt holder  36  guides the fixing belt  30  in a rotatable manner. 
     Temperature control in the image forming apparatus  3  of the present embodiment will be described next with reference to  FIGS.  4  to  6   .  FIG.  4    is a block diagram of elements for temperature control in the image forming apparatus  3  in the present embodiment.  FIGS.  5 A and  5 B  illustrate linear velocity control on the pressure roller  31  according to temperature change of the heater  32  of the fixing device  16  after the image forming apparatus  3  terminates a printing operation.  FIGS.  6 A and  6 B  illustrate linear velocity control on the pressure roller  31  according to temperature change of the heater  32  after the image forming apparatus  3  starts a warmup of the fixing device  16 . 
     As illustrated in  FIG.  4   , the image forming apparatus  3  includes a duration measuring section  40 , a temperature measuring section  41 , a temperature information output section  42 , a temperature tendency computing section  43 , an estimating section  44 , storage  45 , a drive controller  46 , and a pressure roller drive section  47 . At least the temperature information output section  42 , the temperature tendency computing section  43 , the estimating section  44 , and the drive controller  46  are each constituted by an application specific integrated circuit (ASIC). 
     The duration measuring section  40  measures a plurality of times. The temperature measuring section  41  measures a temperature of the heater  32  or the fixing belt  30  at each of the times. The temperature information output section  42  outputs heater temperature information based on the temperatures of the heater at the respective times or outputs fixing belt temperature information based on the temperatures of the fixing belt  30  at the respective times. The temperature tendency computing section  43  outputs temperature tendency information of the heater  32  based on the heater temperature information or outputs temperature tendency information of the fixing belt  30  based on the fixing belt temperature information. 
     The estimating section  44  estimates a temperature of the pressure roller  31  based on the temperature tendency information of the heater  32  or the fixing belt  30 , and outputs pressure roller temperature information. The storage  45  stores reference tendency information therein. The drive controller  46  compares the pressure roller temperature information with the reference tendency information, and outputs linear velocity information for controlling the linear velocity of the pressure roller  31 . The pressure roller drive section  47  drives the pressure roller  31  based on the linear velocity information. 
     The present embodiment will be schematically described below. When the pressure roller  31  is relatively hot, the pressure roller  31  may expand. Due to expansion, the radius of rotation from the non-illustrated axial center to the circumferential surface of the pressure roller  31  may increase. 
     When the pressure roller  31  with an increased radius of rotation is rotated, the linear velocity of the circumferential surface of the pressure roller  31  may be greater than a reference linear velocity. As such, a difference may arise between the actual linear velocity of the pressure roller  31  and the conveyance speed of the sheet S passing through the nip part N between the pressure roller  31  and the fixing belt  30  to cause failure in conveyance of the sheet S. 
     The pressure roller drive section  47  drives the pressure roller  31  at a linear velocity corrected to be later than the reference linear velocity based on the linear velocity information. 
     A specific example of temperature control on the heater  32  of the fixing device  16  by the image forming apparatus  3  will be described next with reference to  FIGS.  5 A and  5 B . First, the duration measuring section  40  measures (times) a plurality of times and outputs time information. The duration measuring section  40  is a timer, for example. 
     The temperature measuring section  41  measures temperatures of the heater  32  at the respective times. The temperature measuring section  41  is disposed in the vicinity of the heater  32 . Examples of the temperature measuring section  41  include a resistance temperature detector, a thermistor, a thermostat, and a thermocouple. The temperature measuring section  41  may measure temperatures of the heater  32  at regular measurement intervals at which the duration measuring section  40  measures the time. The heater temperature information is information indicating the temperatures of the heater  32 . 
     The temperature measuring section  41  may measure temperatures of the fixing belt  30  at the respective times. In this case, the temperature measuring section  41  is disposed in the vicinity of the fixing belt  30 . The temperature measuring section  41  may measure temperatures of the fixing belt  30  at regular measurement intervals at which the duration measuring section  40  measures the times. The fixing belt temperature information is information indicating the temperatures of the fixing belt  30 . 
     The temperature information output section  42  outputs at each of the times the heater temperature information based on the temperatures of the heater  32  at the times or the fixing belt temperature information based on the temperatures of the heater  32  at the times. The heater temperature information may be a combination of the heater temperature information and time information for the heater  32 . The fixing belt temperature information may be a combination of the fixing belt temperature information and time information for the fixing belt  30 . 
     The temperature tendency computing section  43  outputs the temperature tendency information of the heater  32  based on the heater temperature information or outputs the temperature tendency information of the fixing belt  30  based on the fixing belt temperature information. 
     In one example, the temperature tendency computing section  43  computes temperature tendency information on a tendency A, a tendency B, and a tendency C based on detection information, as illustrated in  FIGS.  5 A and  5 B . The temperature tendency computing section  43  acquires an average gradient of drops of the measured temperatures of the heater  32  relative to the times in the order of lapsed time based on the temperature tendency information illustrated in  FIGS.  5 A and  5 B  after fixing operation of the fixing device  16  terminates. 
     The estimating section  44  estimates a temperature of the pressure roller  31  as the pressure roller temperature information based on the temperature tendency information, and outputs the pressure roller temperature information. The estimating section  44  estimates a temperature of the pressure roller  31  based on the temperature tendency information per time lapse. Alternatively, the estimating section  44  may estimate a rapid drop of the temperature of the pressure roller  31  in a case of the tendency A. 
     The tendency A is a tendency of the temperature of the heater  32  as an example in a case in which fixing to a small number of sheets S such as one sheet S is performed after a long time has passed since the fixing device  16  has been in operation. The tendency A has an average gradient of (−20). The pressure roller  31  is sufficiently cool before being driven in this case. As such, the temperature of the pressure roller  31  rapidly drops after a drive stop thereof. 
     The storage  45  stores reference tendency information therein. The storage  45  may store the tendency A therein as the reference tendency information. 
     The drive controller  46  compares the pressure roller temperature information with the reference tendency information and outputs linear velocity information for controlling the linear velocity of the pressure roller  31 . The pressure roller drive section  47  drives the pressure roller  31  based on the linear velocity information. That is, the drive controller  46  performs control based on the reference tendency information and the pressure roller temperature information so that the pressure roller  31  is driven at a preferable linear velocity. The drive controller  46  may perform control so that the linear velocity of the pressure roller  31  is a reference linear velocity (with a correction amount of 0). 
     In other words, the pressure roller temperature information indicates expansion of the pressure roller  31  due to temperature change. That is, the drive controller  46  can control the linear velocity of the pressure roller  31  according to expansion of the pressure roller  31  due to temperature change. 
     The pressure roller drive section  47  drives the pressure roller  31  at a preferable linear velocity based on the linear velocity information. The pressure roller drive section  47  may drive the pressure roller  31  at the reference linear velocity based on the linear velocity information. 
     The tendency B indicated in  FIG.  5 A  is a temperature tendency of the heater  32  as an example in a case in which the fixing device  16  has been in a sleep state. As illustrated in  FIG.  5 B , the tendency B has an average gradient of (−15). The pressure roller  31  is relatively cool before being driven. As such, the temperature of the pressure roller  31  more gently drops after a drive stop than that in a case of the tendency A. 
     The estimating section  44  estimates a temperature of the pressure roller  31  per time lapse based on the temperature tendency information. The estimating section  44  estimates a gentle drop of the temperature of the pressure roller  31  in a case of the tendency B. 
     The drive controller  46  performs control based on the reference tendency information and the pressure roller temperature information so that the pressure roller  31  is driven at a linear velocity corrected by (−5). The pressure roller drive section  47  may drive the pressure roller  31  at a linear velocity lower by (−5) than the reference linear velocity based on the linear velocity information. 
     The tendency C indicated in  FIG.  5 A  is a temperature tendency of the heater  32  as an example in a case in which the fixing device  16  has been in operation for a long time. As illustrated in  FIG.  5 B , the tendency C has an average gradient of (−10). The pressure roller  31  is relatively hot before being driven. As such, the temperature of the pressure roller  31  further more gently drops after a drive stop than that in cases of the tendencies A and B. 
     The estimating section  44  estimates a temperature of the pressure roller  31  based on the temperature tendency information per time lapse. The estimating section  44  estimates the temperature of the pressure roller  31  being relatively high in a case of the tendency C. 
     The drive controller  46  performs control based on the reference tendency information and the pressure roller temperature information so that the pressure roller  31  is driven at a linear velocity corrected by (−10). The pressure roller drive section  47  may drive the pressure roller  31  at a linear velocity lower by (−10) than the reference linear velocity based on the linear velocity information. 
     The drive controller  46  can control the linear velocity of the pressure roller  31  according to expansion of the pressure roller  31  due to temperature change in the present embodiment. Accordingly, the difference between the linear velocity of the pressure roller  31  and the conveyance speed of the sheet S passing through the nip part N between the pressure roller  31  and the fixing belt  30  can be reduced, thereby preventing production of failure in conveyance of the sheet S. 
     The duration measuring section  40  may measure (time) a predetermined time period T (predetermined time T) from a stop of the fixing device  16 . The drive controller  46  may control the pressure roller drive section  47  to drive the pressure roller  31  based on the linear velocity information only when a restart instruction is received in the predetermined time period T starting from a stop of the fixing device  16 . 
     According to the present embodiment, the pressure roller  31  can be driven at a preferable linear velocity by effectively utilizing the pressure roller temperature information indicating expansion of the pressure roller  31  due to temperature change. 
     In addition, the duration measuring section  40  may measure (time) a predetermined time period T (predetermined time T) from a stop of the fixing device  16 . The drive controller  46  may invalidate the pressure roller temperature information when the restart instruction is not received in the predetermined time period T starting from a stop of the fixing device  16 . In this case, the drive controller  46  may delete the pressure roller temperature information. The drive controller  46  may control the pressure roller drive section  47  so as to drive the pressure roller  31  at the reference linear velocity. 
     In the present embodiment, the pressure roller  31  can be driven at the reference linear velocity when the restart instruction is received after a sufficient time period elapses from a stop of the fixing device  16 . 
     Another example of the temperature control on the heater  32  of the fixing device  16  by the image forming apparatus  3  will be described next with reference to  FIGS.  6 A and  6 B . As illustrated in  FIGS.  6 A and  6 B , the temperature tendency computing section  43  computes temperature tendency information on a tendency D, a tendency E, and a tendency F based on the detection information. The temperature tendency information illustrated in  FIGS.  6 A and  6 B  indicates average gradients of increases in the measured temperature of the heater  32  relative to the times in the order of elapsed time after a warmup start of the fixing device  16 . 
     In the present embodiment, the duration measuring section  40  measures a predetermined time period T starting from a warmup start of the fixing device  16 . 
     The tendency D is a temperature tendency of the heater  32  as an example in a case in which the fixing device  16  warms up after the fixing device  16  has not been in operation for a long time. The duration measuring section  40  measures the predetermined time period T starting from a warmup start of the fixing device  16 . The tendency D has an average gradient of (+10) in the predetermined time period T. When the fixing device  16  has not been in operation for a long time, the pressure roller  31  is sufficiently cool before being driven. As such, the temperature of the pressure roller  31  gently increases after a warmup start. 
     The estimating section  44  estimates a temperature of the pressure roller  31  per time lapse based on the temperature tendency information. The estimating section  44  estimates a gentle increase of the temperature of the pressure roller  31  in a case of the tendency D. 
     The drive controller  46  performs control based on the reference tendency information and the pressure roller temperature information so that the pressure roller  31  is driven at the reference linear velocity (corrected by (0)). The pressure roller drive section  47  drives the pressure roller  31  at the reference linear velocity based on the linear velocity information. 
     The tendency E is a temperature tendency of the heater  32  as an example in a case in which the fixing device  16  has been in a sleep state. The tendency E has an average gradient of (+15). The pressure roller  31  is relatively hot before being driven. As such, the temperature thereof more rapidly increases after a warmup start than that in a case of the tendency D. 
     The estimating section  44  estimates a temperature of the pressure roller  31  based on the temperature tendency information per time lapse. The estimating section  44  estimates a rapid increase of the temperature of the pressure roller  31  in a case of the tendency E. 
     The drive controller  46  performs control based on the reference tendency information and the pressure roller temperature information so that the pressure roller  31  is driven at a linear velocity corrected by (−5). The pressure roller drive section  47  drives the pressure roller  31  at a linear velocity lower by (−5) than the reference linear velocity based on the linear velocity information. 
     The tendency F is a temperature tendency of the heater  32  as an example in a case in which the fixing device  16  warms up after the fixing device  16  has been in operation for a long time. The tendency F has an average gradient of (+20). The pressure roller  31  is relatively hot before being driven. As such, the temperature of the pressure roller  31  further more rapidly increases after a drive stop than that in cases of the tendencies D and E. 
     The estimating section  44  estimates a temperature of the pressure roller  31  per time lapse based on the temperature tendency information. The estimating section  44  estimates the temperature of the pressure roller  31  being relatively high in a case of the tendency F. 
     The drive controller  46  performs control based on the reference tendency information and the pressure roller temperature information so that the pressure roller  31  is driven at a linear velocity corrected by (−10). The pressure roller drive section  47  drives the pressure roller  31  at a linear velocity lower by (−10) than the reference linear velocity based on the linear velocity information. 
     In the present embodiment, the linear velocity of the pressure roller  31  can be controlled according to the state of the fixing device  16  before a warmup start. Accordingly, the difference between the linear velocity of the pressure roller  31  and the conveyance speed of the sheet S passing through the nip part N between the pressure roller  31  and the fixing belt  30  can be reduced, thereby preventing production of failure in conveyance of the sheet S. 
     The control in the image forming apparatus  3  in the present embodiment will be described next with reference to  FIG.  7   .  FIG.  7    is a flowchart depicting the control in the image forming apparatus  3  according to the present embodiment. 
     As depicted in  FIG.  7   , the routine includes Steps S 10  to S 24 . Specifics are as follows. 
     In step  10 , the duration measuring section  40  measures a plurality of times. The routine proceeds to Step S 12 . 
     In Step S 12 , the temperature measuring section  41  measures the temperature of the heater  32  and outputs the heater temperature information, or measures the temperature of the fixing belt  30  and outputs the fixing belt temperature information. The routine proceeds to Step S 14 . 
     In Step S 14 , the temperature information output section  42  detects temperatures of the heater  32  at the respective times based on the heater temperature information or detects temperatures of the fixing belt  30  at the respective times based on the fixing belt temperature information, and outputs the detection information. The routine proceeds to Step S 16 . 
     In Step S 16 , the temperature tendency computing section  43  outputs the temperature tendency information of the heater  32  or the fixing belt  30  based on the detection information. The routine proceeds to Step S 18 . 
     In Step S 18 , the estimating section  44  estimates a temperature of the pressure roller  31  based on the temperature tendency information and outputs the pressure roller temperature information. The routine proceeds to Step S 20 . 
     In Step S 20 , the storage  45  stores the reference tendency information. The routine proceeds to Step S 22 . 
     In Step S 22 , the drive controller  46  compares the pressure roller temperature information with the reference tendency information and outputs the linear velocity information for controlling the linear velocity of the pressure roller  31 . The routine proceeds to Step S 24 . 
     In Step S 24 , the pressure roller drive section  47  drives the pressure roller  31  based on the linear velocity information. The routine ends then. 
     Another temperature control in the image forming apparatus  3  in the present embodiment will be described next with reference to  FIG.  8   .  FIG.  8    is a flowchart depicting the other temperature control in the image forming apparatus  3  according to the present embodiment. 
     As depicted in  FIG.  8   , the routine includes Steps S 30  to S 58 . Specifics are as follows. 
     In step S 30 , the printer controller  10  determines whether or not the image forming apparatus  3  is in the standby state as depicted in  FIG.  8   . If it is determined that the image forming apparatus  3  is in the standby state (Yes in Step S 30 ), the routine proceeds to Step S 32 . If it is determined that the image forming apparatus  3  is not in the standby state (No in Step S 30 ), the routine proceeds to Step S 50 . 
     In step S 32 , the printer controller  10  grasps the state of the image forming apparatus  3 . The routine proceeds to Step S 34 . 
     In Step S 34 , the drive controller  46  determines whether or not it is necessary to correct the temperature of the pressure roller  31 . If it is determined that it is necessary to correct the temperature of the pressure roller  31 , the routine proceeds to Step S 36 . If it is determined that it is not necessary to correct the temperature of the pressure roller  31 , the routine proceeds to Step S 40 . 
     If an affirmative determination is made in Step S 34 , the drive controller  46  determines a correction amount for correcting the temperature of the pressure roller  31  in Step S 36 . The routine proceeds to Step S 38 . 
     In step S 38 , the drive controller  46  determines control at a corrected temperature on the pressure roller  31 . The routine ends then. 
     If a negative determination is made in Step S 34 , the drive controller  46  determines not to correct the temperature of the pressure roller  31  in Step S 36 . 
     If a negative determination is made in Step S 30 , the temperature tendency computing section  43  grasps a temperature increase tendency of the pressure roller  31  in Step S 50 . The routine proceeds to Step S 52 . 
     In Step S 52 , the drive controller  46  determines whether or not it is necessary to correct the temperature of the pressure roller  31 . If it is determined that it is necessary to correct the temperature of the pressure roller  31 , the routine proceeds to Step S 54 . If it is determined that it is not necessary to correct the temperature of the pressure roller  31 , the routine proceeds to Step S 58 . 
     If an affirmative determination is made in Step S 52 , the drive controller  46  determines a correction amount for correcting the temperature of the pressure roller  31  in Step S 54 . The routine proceeds to Step S 56 . 
     In step S 56 , the drive controller  46  determines control to drive the pressure roller  31  at the corrected temperature. The routine ends then. 
     If a negative determination is made in Step S 52 , the drive controller  46  determines not to correct the temperature of the pressure roller  31 . 
     An embodiment of the present disclosure has been described so far with reference to the drawings. However, the present disclosure is not limited to the above embodiment and may be implemented in various different forms that do not deviate from the essence of the present disclosure. The drawings schematically illustrate elements of configuration in order to facilitate understanding, and properties of elements of configuration illustrated in the drawings, such as thickness, length, and number thereof, may differ from actual properties thereof in order to facilitate preparation of the drawings. Furthermore, properties of elements of configuration described in the above embodiment, such as material, shape, and dimensions, are merely examples and are not intended as specific limitations. Various alterations may be made so long as there is no substantial deviation from the effects of the present disclosure.