Image forming device

Abstract

To provide an image forming apparatus that can control a linear velocity of a pressure roller on the basis of, a change in a temperature of the pressure roller.SOLUTION: A clocking unit 40 clocks a plurality of times. A temperature measurement unit 41 measures temperatures of a heater 32 at the plurality of times. A temperature information output unit 42 outputs heater temperature information on the basis of, the temperatures of the heater 32 at the plurality of times. A temperature characteristic calculation unit 43 outputs temperature characteristic information on the heater 32 on the basis of, the heater temperature information. A drive control unit 46 outputs linear velocity information for controlling a linear velocity of the pressure roller 31 on the basis of, the temperature characteristic information. A pressure roller driving unit 47 drives the pressure roller 31 on the basis of, the linear velocity information.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses a technique for dealing with an excessive temperature rise in a fixing device when an uncontrollable state of a heater occurs due to an abnormality in a thermistor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-137054 A Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 does not mention any problem with the fixing state caused by contraction or expansion of the pressure roller.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus that controls the linear speed of a pressure roller based on a change in temperature of the pressure roller. [Means for solving the problem]

[0006] The present invention is an image forming apparatus including a fixing device. The fixing device includes a fixing belt, a heater, and a pressure roller. The fixing belt heats and fixes a toner image transferred to a sheet. The heater heats the fixing belt. The pressure roller rotates in contact with the fixing belt. The image forming apparatus includes a clocking unit, a temperature measuring unit, a temperature information output unit, a temperature characteristic calculation unit, a drive control unit, and a pressure roller drive unit. The clocking unit measures a plurality of times. The temperature measuring unit measures the temperature of the heater or the temperature of the fixing belt at the plurality of times. The temperature information output unit outputs heater temperature information or fixing belt temperature information based on the temperature of the heater or the temperature of the fixing belt at the plurality of times. The temperature characteristic calculation unit outputs temperature characteristic information of the heater or the fixing belt based on the heater temperature information or the fixing belt temperature information. The drive control unit outputs linear speed information for controlling the linear speed of the pressure roller based on the temperature characteristic information. The pressure roller drive unit drives the pressure roller based on the linear speed information. Effect of the Invention

[0007] According to the image forming apparatus of the present invention, the linear speed of the pressure roller can be controlled based on the temperature change of the pressure roller. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a multifunction peripheral including an image forming apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a block diagram showing a configuration of an image forming apparatus according to an embodiment of the present invention; [Diagram 3] 2 is a cross-sectional view showing a configuration of a fixing device provided in the image forming apparatus according to the embodiment; [Figure 4] FIG. 2 is a block diagram showing components related to temperature control of the fixing device. [Diagram 5] 13A and 13B are diagrams illustrating control of the linear speed of the pressure roller based on a change in temperature of the heater after the fixing device has stopped operating. [Figure 6] 13A and 13B are diagrams illustrating control of the linear speed of a pressure roller based on a change in heater temperature after the fixing device starts warming up. [Figure 7] 5 is a flowchart showing temperature control of the fixing device. [Figure 8] 10 is a flowchart showing another example of temperature control of the fixing device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference symbols and the description will not be repeated. In this embodiment, the drawings show an X-axis, a Y-axis, and a Z-axis that are perpendicular to each other. The Z-axis is parallel to the vertical plane, and the X-axis and the Y-axis are parallel to the horizontal plane.

[0010] In this embodiment, the Z-axis direction may be referred to as the "main scanning direction", the Y-axis direction may be referred to as the "sub-scanning direction", and the X-axis direction may be referred to as the "direction perpendicular to the main scanning direction and the sub-scanning direction".

[0011] The configuration of a multifunction peripheral 1 will be described with reference to Fig. 1. Fig. 1 is a diagram showing the multifunction peripheral 1 equipped with a fixing device 16 according to the present embodiment. The configuration of an image forming apparatus 3 equipped with the fixing device 16 according to the present embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the configuration of an image forming apparatus 3 equipped with the fixing device 16 according to the present embodiment.

[0012] 1, the multifunction device 1 includes a document reading device 2 and an image forming device 3. The multifunction device 1 is, for example, an MFP (Multi Function Printer) that combines the functions of a scanner, a copier, a printer, a copy machine, a facsimile, and other devices.

[0013] The document reading device 2 includes, for example, a document tray, a document feeding section, a document transport section, a document reading section, optical members, a document discharge section, and a document discharge tray.

[0014] The image forming apparatus 3 includes a printer control unit 10, a printer driving unit 11, a sheet tray 12, a sheet feeding unit 13, a sheet transport unit 14, an image forming unit 15, a fixing unit 16, a sheet discharge unit 17, and a sheet discharge tray 18.

[0015] The printer control unit 10 controls the operation of each unit of the image forming device 3. The printer control unit 10 may function as a control unit that controls the operation of each unit of the multifunction device 1. Specific examples of the printer control unit 10 include a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), or an ASIC (Application Specific Integrated Circuit).

[0016] The printer drive unit 11 drives each part of the image forming device 3. The printer drive unit 11 may be a drive unit that operates each part of the multifunction device 1. Specific examples of the printer drive unit 11 are an electric motor, an electromagnetic solenoid, a hydraulic cylinder, and a pneumatic cylinder.

[0017] The sheet tray 12 stacks the sheets S. The sheets S are an example of a recording medium. The sheet tray 12 may include a tray and a lifting member. The sheet feeding unit 13 picks up and feeds the sheets S stacked on the sheet tray 12. A specific example of the sheet feeding unit 13 is a pickup roller.

[0018] The sheet conveying unit 14 conveys the sheet S fed from the sheet tray 12. The sheet conveying unit 14 has a conveying path. The conveying path starts from the sheet tray 12, passes through the image forming unit 15 and the fixing unit 16, and extends to a sheet discharge unit 17. The sheet conveying unit 14 may include a conveying roller and a registration roller in the conveying path.

[0019] A plurality of transport rollers may be disposed on the transport path and transport the sheet S. The registration rollers adjust the timing of transporting the sheet S to the image forming unit 15. The sheet transport unit 14 transports the sheet S from the sheet tray 12 to the sheet discharge unit 17 via the image forming unit 15 and the fixing unit 16.

[0020] The image forming unit 15 forms a toner image (not shown) on the sheet S by electrophotography based on the document image data. The document image data indicates an image of the original G, for example.

[0021] The fixing unit 16 applies heat and pressure to the toner image developed on the sheet S to fix the toner image to the sheet S.

[0022] The sheet discharge section 17 discharges the sheet S to the outside of the housing of the multifunction device 1 (image forming device 3). A specific example of the sheet discharge section 17 is a discharge roller.

[0023] The sheet discharge tray 18 holds the sheets S discharged by the sheet discharge section 17.

[0024] Next, a detailed configuration of the fixing device 16 according to the present embodiment will be described with reference to Fig. 3. Fig. 3 is a cross-sectional view showing the configuration of the fixing device 16 according to the present embodiment.

[0025] As shown 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 stay metal plate , a stay metal plate holding portion , and a fixing belt holding portion .

[0026] The fixing belt 30 heats the sheet S (FIG. 1) on which a toner image has been formed in the image forming section 15 shown in FIG. 1 and conveyed to the fixing device 16, thereby fixing the toner image transferred to the sheet S by heat.

[0027] 3 is endless. The fixing belt 30 has a substantially cylindrical shape. The fixing belt 30 is flexible.

[0028] The fixing belt 30 further includes a plurality of layers. For example, the fixing belt 30 includes a polyimide layer including polyimide, an elastic layer including an elastic material such as silicone rubber, and a release layer. The release layer is formed on the outer peripheral surface of the polyimide layer. The release layer is, for example, a heat-resistant film made of a fluororesin.

[0029] The pressure member 31 is in pressure contact (contact) with the fixing belt 30 while being driven to rotate, and causes the fixing belt 30 to rotate. The pressure member 31 is substantially cylindrical, and is disposed opposite the fixing belt 30. An example of the pressure member 31 is a pressure roller. Hereinafter, the pressure member 31 may be referred to as the "pressure roller 31."

[0030] The pressure roller 31 has a cylindrical core, a cylindrical elastic layer, and a release layer. The elastic layer is formed on the core. The release layer is formed so as to cover the surface of the elastic layer.

[0031] The core metal is made of, for example, stainless steel or aluminum. The elastic layer has elasticity and is made of, for example, silicone rubber. The release layer is made of, for example, fluororesin.

[0032] The heater 32 is connected to a power source (not shown) and generates heat. The heater 32 heats the fixing belt 30. The heater 32 is disposed at a position facing the inner circumferential surface of the fixing belt 30.

[0033] The heater 32 is, for example, a planar heater or a long and thin plate heater. The heater 32 is, for example, a ceramic heater, and includes a ceramic substrate and a resistance heating element. The heater 32 has a thickness of, for example, 1 mm. The heater 32 receives pressure from the pressure roller 31 via the fixing belt 30.

[0034] The pressure roller 31 is pressed against the fixing belt 30, thereby forming a nip N at the contact portion between the fixing belt 30 and the pressure roller 31. The pressure roller 31 is pressed against the fixing belt 30, thereby causing the heater 32 to be pressed against the inner circumferential surface of the fixing belt 30. Therefore, the fixing belt 30 is heated by the heater 32, and a toner image formed on a sheet S (FIG. 1) passing through the nip N is fixed to the sheet S.

[0035] The heater holding member 33 guides the fixing belt 30 so as to be able to rotate, and holds the heater 32 that heats the fixing belt 30 .

[0036] The stay metal plate 34 reinforces the heater holding member 33. The stay metal plate 34 is, for example, an elongated metallic stay member. The stay metal plate 34 may be formed in a U-shape, a C-shape, or a V-shape.

[0037] The stay sheet metal holding portion 35 holds the stay sheet metal 34 so as to fix it to the heater holding member 33 .

[0038] The fixing belt holding portion 36 guides the fixing belt 30 so as to be able to rotate.

[0039] Next, the temperature control of the image forming apparatus 3 according to this embodiment will be described with reference to Figs. 4 to 6. Fig. 4 is a block diagram showing components related to the temperature control of the image forming apparatus 3 according to this embodiment. Figs. 5(a) and (b) are diagrams showing linear speed control of the pressure roller 31 based on the temperature change of the heater 32 of the fixing device 16 after the image forming apparatus 3 finishes the printing operation. Figs. 6(a) and (b) are diagrams showing linear speed control of the pressure roller 31 based on the temperature change of the heater 32 after the image forming apparatus 3 starts warming up the fixing device 16.

[0040] 4, the image forming apparatus 3 includes a timer unit 40, a temperature measurement unit 41, a temperature information output unit 42, a temperature characteristic calculation unit 43, an estimation unit 44, a storage unit 45, a drive control unit 46, and a pressure roller drive unit 47. At least the temperature information output unit 42, the temperature characteristic calculation unit 43, the estimation unit 44, and the drive control unit 46 may be configured by an ASIC (Application Specific Integrated Circuit).

[0041] The timing unit 40 measures a plurality of times. The temperature measurement unit 41 measures the temperature of the heater 32 or the temperature of the fixing belt 30 at a plurality of times. The temperature information output unit 42 outputs heater temperature information or fixing belt temperature information based on the temperature of the heater 32 or the temperature of the fixing belt 30 at a plurality of times. The temperature characteristic calculation unit 43 outputs temperature characteristic information of the heater 32 or the fixing belt 30 based on the heater temperature information or the fixing belt temperature information.

[0042] The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information, and outputs pressure roller temperature information. The storage unit 45 stores the reference characteristic information. The drive control unit 46 compares the reference characteristic information with the pressure roller temperature information, and outputs linear speed information for controlling the linear speed of the pressure roller 31. The pressure roller drive unit 47 drives the pressure roller 31 based on the linear speed information.

[0043] An outline of this embodiment will be described. When the pressure roller 31 is at a relatively high temperature, the pressure roller 31 may expand. Therefore, the rotation radius from the axis (not shown) of the pressure roller 31 to the circumferential surface becomes large.

[0044] When the pressure roller 31 is rotated with the rotation radius increased, the linear speed of the peripheral surface of the pressure roller 31 becomes higher than the reference linear speed. Therefore, an error occurs between the conveying speed of the sheet S passing through the nip portion N between the pressure roller 31 and the fixing belt 30 and the linear speed of the pressure roller 31, which may cause a problem in conveying the sheet S.

[0045] The pressure roller driving unit 47 drives the pressure roller 31 at a linear speed corrected to a speed slower than the reference linear speed based on the linear speed information.

[0046] Next, a specific embodiment in which the image forming apparatus 3 controls the temperature of the heater 32 of the fixing device 16 will be described with reference to Fig. 5. First, the timing unit 40 times (measures) multiple times and outputs time information. An example of the timing unit 40 is a timer.

[0047] The temperature measurement unit 41 measures the temperature of the heater 32 at multiple times. The temperature measurement unit 41 is disposed in the vicinity of the heater 32. Examples of the temperature measurement unit 41 are a resistance temperature detector, a thermistor, a thermostat, and a thermocouple. The temperature measurement unit 41 may measure the temperature of the heater 32 at each predetermined measurement time measured by the timing unit 40. The heater temperature information is information indicating the temperature of the heater 32.

[0048] The temperature measurement unit 41 may measure the temperature of the fixing belt 30 at a plurality of times. The temperature measurement unit 41 is disposed in the vicinity of the fixing belt 30. The temperature measurement unit 41 may measure the temperature of the fixing belt 30 at each predetermined measurement time measured by the timing unit 40. The fixing belt temperature information is information indicating the temperature of the fixing belt 30.

[0049] The temperature information output unit 42 outputs heater temperature information or fixing belt temperature information based on the temperature of the heater 32 or the temperature of the fixing belt 30 at multiple times. The heater temperature information may be a combination of time information and heater temperature information related to the heater 32. The fixing belt temperature information may be a combination of time information and fixing belt temperature information related to the fixing belt 30.

[0050] The temperature characteristic calculation unit 43 outputs temperature characteristic information of the heater 32 or the fixing belt 30 based on the heater temperature information or the fixing belt temperature information.

[0051] 5(a) and (b), the temperature characteristic calculation unit 43 calculates temperature characteristic information of characteristics A, B, and C based on the detection information. Based on the temperature characteristic information shown in FIG. 5(a) and (b), the temperature characteristic calculation unit 43 obtains an average gradient of the amount of decrease in the measured temperature of the heater 32 with respect to a plurality of elapsed times after the fixing device 16 finishes the fixing operation.

[0052] The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information, and outputs the pressure roller temperature information. The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information at each time point. Furthermore, in the case of characteristic A, the estimation unit 44 may estimate that the temperature of the pressure roller 31 is rapidly decreasing.

[0053] Characteristic A is, as an example, a characteristic when the fixing device 16 has not been in operation for a long time and a small number of sheets S, such as one sheet, are fixed. The average gradient of characteristic A is (-20). Since the pressure roller 31 was at a sufficiently low temperature before being driven, the temperature drops rapidly after driving is stopped.

[0054] The storage unit 45 stores the reference characteristic information. The storage unit 45 may store the characteristic A as the reference characteristic information.

[0055] The drive control unit 46 compares the reference characteristic information with the pressure roller temperature information, and outputs linear speed information for controlling the linear speed of the pressure roller 31. The pressure roller drive unit 47 drives the pressure roller 31 based on the linear speed information. That is, the drive control unit 46 controls the pressure roller 31 to be driven at an appropriate linear speed based on the reference characteristic information and the pressure roller temperature information. The drive control unit 46 may control the linear speed of the pressure roller 31 to be the reference linear speed (to be 0 correction amount).

[0056] In other words, the pressure roller temperature information indicates the temperature expansion of the pressure roller 31. That is, the drive control unit 46 can control the linear speed of the pressure roller 31 based on the temperature expansion of the pressure roller 31.

[0057] The pressure roller driving unit 47 drives the pressure roller 31 at a suitable linear speed based on the linear speed information. The pressure roller driving unit 47 may drive the pressure roller 31 at a reference linear speed based on the linear speed information.

[0058] Characteristic B shown in Fig. 5(a) is, as an example, a characteristic when the fixing device 16 is in a sleep state. As shown in Fig. 5(b), the average gradient of characteristic B is (-15). Since the pressure roller 31 was at a relatively low temperature before driving, the temperature drops more slowly after driving is stopped than in the case of characteristic A.

[0059] The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information at each time point. In the case of characteristic B, the estimation unit 44 estimates that the temperature of the pressure roller 31 is gradually decreasing.

[0060] The drive control unit 46 controls the linear velocity of the pressure roller 31 to a linear velocity corrected by (-5) based on the reference characteristic information and the pressure roller temperature information. The pressure roller drive unit 47 may drive the pressure roller 31 at a linear velocity slower by (-5) than the reference linear velocity based on the linear velocity information.

[0061] Characteristic C shown in Fig. 5(a) is, as an example, a characteristic when the fixing device 16 has been in operation for a long time. As shown in Fig. 5(b), the average gradient of characteristic C is (-10). Since the pressure roller 31 was relatively hot before it was driven, the temperature after it was stopped drops more slowly than in the cases of characteristics A and B.

[0062] The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information at each time point. In the case of characteristic C, the estimation unit 44 estimates that the temperature of the pressure roller 31 is relatively high.

[0063] The drive control unit 46 controls the linear velocity of the pressure roller 31 to a linear velocity corrected by (-10) based on the reference characteristic information and the pressure roller temperature information. The pressure roller drive unit 47 may drive the pressure roller 31 at a linear velocity slower by (-10) than the reference linear velocity based on the linear velocity information.

[0064] According to this embodiment, the linear speed of the pressure roller 31 can be controlled based on the temperature expansion of the pressure roller 31. Then, the error between the conveying speed of the sheet S passing through the nip portion N between the pressure roller 31 and the fixing belt 30 and the linear speed of the pressure roller 31 can be suppressed, so that problems in conveying the sheet S can be suppressed.

[0065] The timing unit 40 may time (measure) a predetermined time T (predetermined time T) after the fixing device 16 has stopped. The drive control unit 46 may control the pressure roller drive unit 47 to drive the pressure roller 31 based on the linear speed information only when an instruction to restart is received within the predetermined time after the fixing device 16 has stopped.

[0066] According to this embodiment, the pressure roller temperature information indicating the thermal expansion of the pressure roller 31 is effectively utilized, so that the pressure roller 31 can be driven at a suitable linear speed.

[0067] Furthermore, the timing unit 40 may time (measure) a predetermined time T (predetermined time T) after the fixing device 16 has stopped. The drive control unit 46 may invalidate the pressure roller temperature information if an instruction to restart is not received within the predetermined time after the fixing device 16 has stopped. In this case, the drive control unit 46 may erase the pressure roller temperature information. The drive control unit 46 may control the pressure roller drive unit 47 to drive the pressure roller 31 at the reference linear speed.

[0068] According to this embodiment, when a command to restart is received after a sufficient time has elapsed since the fixing device 16 was stopped, the pressure roller 31 can be driven at the reference linear speed.

[0069] Next, still referring to Figures 6(a) and (b), another embodiment in which the image forming apparatus 3 controls the temperature of the heater 32 of the fixing device 16 will be described. As shown in Figures 6(a) and (b), the temperature characteristic calculation unit 43 calculates temperature characteristic information of characteristics D, E, and F based on the detection information. The temperature characteristic information shown in Figures 6(a) and (b) indicates the average gradient of the amount of increase in the measured temperature of the heater 32 with respect to the elapsed time at multiple times after the fixing device 16 starts warming up.

[0070] In this embodiment, the timing unit 40 measures a predetermined time T from when the fixing device 16 starts warming up.

[0071] As an example, characteristic D is a characteristic when fixing device 16 warms up after not operating for a long time. Timer 40 measures a predetermined time T after fixing device 16 starts warming up. The average gradient of characteristic D at the predetermined time T is (+10). When fixing device 16 has not operated for a long time, pressure roller 31 was at a sufficiently low temperature before being driven, so the temperature rises slowly after warming up begins.

[0072] The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information at each time point. In the case of characteristic D, the estimation unit 44 estimates that the temperature of the pressure roller 31 is rising slowly.

[0073] The drive control unit 46 controls the linear speed of the pressure roller 31 to be the reference linear speed (to be the correction amount 0) based on the reference characteristic information and the pressure roller temperature information. The pressure roller drive unit 47 drives the pressure roller 31 at the reference linear speed based on the linear speed information.

[0074] Characteristic E is, as an example, a characteristic when the fixing device 16 is in a sleep state. The average gradient of characteristic E is (+15). Since the pressure roller 31 was relatively hot before it was driven, the temperature rises faster after the warm-up starts than in the case of characteristic D.

[0075] The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information for each elapsed time. In the case of characteristic E, the estimation unit 44 estimates that the temperature of the pressure roller 31 is rising rapidly.

[0076] The drive control unit 46 controls the linear velocity of the pressure roller 31 to a linear velocity corrected by (-5) based on the reference characteristic information and the pressure roller temperature information. The pressure roller drive unit 47 drives the pressure roller 31 at a linear velocity slower by (-5) than the reference linear velocity based on the linear velocity information.

[0077] Characteristic F is, as an example, a characteristic when the fixing device 16 starts warming up after being in operation for a long time. The average gradient of characteristic F is (+20). Since the pressure roller 31 was relatively hot before being driven, the temperature rises more rapidly after driving is stopped than in the cases of characteristics D and E.

[0078] The estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information at each time point. In the case of characteristic F, the estimation unit 44 estimates that the temperature of the pressure roller 31 is relatively high.

[0079] The drive control unit 46 controls the linear velocity of the pressure roller 31 to a linear velocity corrected by (-10) based on the reference characteristic information and the pressure roller temperature information. The pressure roller drive unit 47 drives the pressure roller 31 at a linear velocity slower by (-10) than the reference linear velocity based on the linear velocity information.

[0080] According to this embodiment, the linear speed of the pressure roller 31 can be controlled according to the state before the fixing device 16 starts warming up. Therefore, it is possible to suppress the error between the conveying speed of the sheet S passing through the nip portion N between the pressure roller 31 and the fixing belt 30 and the linear speed of the pressure roller 31, and therefore it is possible to suppress problems in conveying the sheet S.

[0081] Next, the control of the image forming apparatus 3 according to this embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the control of the image forming apparatus 3 according to this embodiment.

[0082] 7, the process includes steps S10 to S24. Specifically, the process is as follows.

[0083] In step S10, the timing unit 40 times a plurality of times. The process proceeds to step S12.

[0084] In step S12, the temperature measurement unit 41 measures the temperature of the heater 32 or the temperature of the fixing belt 30, and outputs heater temperature information or fixing belt temperature information. The process proceeds to step S14.

[0085] In step S14, the temperature information output section 42 detects the temperatures of the heater 32 or the fixing belt 30 at a plurality of times based on the heater temperature information or the fixing belt temperature information, and outputs the detection information. The process proceeds to step S16.

[0086] In step S16, the temperature characteristic calculation unit 43 outputs, based on the detection information, temperature characteristic information of the heater 32 or the fixing belt 30. The process proceeds to step S18.

[0087] In step S18, the estimation unit 44 estimates the temperature of the pressure roller 31 based on the temperature characteristic information, and outputs pressure roller temperature information. The process proceeds to step S20.

[0088] In step S20, the storage unit 45 stores the reference characteristic information. The process proceeds to step S22.

[0089] In step S22, the drive control unit 46 compares the reference characteristic information with the pressure roller temperature information, and outputs linear speed information for controlling the linear speed of the pressure roller 31. The process proceeds to step S24.

[0090] In step S24, the pressure roller driving unit 47 drives the pressure roller 31 based on the linear speed information, and the process then ends.

[0091] Next, another temperature control of the image forming apparatus 3 according to the present embodiment will be described with reference to Fig. 8. Fig. 8 is a flow chart showing another temperature control of the image forming apparatus 3 according to the present embodiment.

[0092] 8, the process includes steps S30 to S58. Specifically, the process is as follows.

[0093] 8, in step S30, the printer control unit 10 determines whether the image forming device 3 is in a ready-standby state. If it is in a ready-standby state (Yes in step S30), the process proceeds to step S32. If it is not in a ready-standby state (No in step S30), the process proceeds to step S50.

[0094] In step S32, the printer control unit 10 determines the state of the image forming device 3. The process proceeds to step S34.

[0095] In step S34, the drive control unit 46 determines whether or not it is necessary to correct the temperature of the pressure roller 31. If it is necessary to correct, the process proceeds to step S36. If it is not necessary to correct, the process proceeds to step S40.

[0096] If the result of step S34 is Yes, the drive control unit 46 determines the amount of correction for correcting the temperature of the pressure roller 31. The process proceeds to step S38.

[0097] In step S38, the drive control unit 46 determines the control to drive the pressure roller 31 at the corrected temperature, and then the process ends.

[0098] If the result is No in step S34, the drive control unit 46 determines not to correct the temperature of the pressure roller 31.

[0099] If the result of step S30 is No, then in step S50, the temperature characteristic calculation unit 43 determines the temperature rise characteristic of the pressure roller 31. The process proceeds to step S52.

[0100] In step S52, the drive control unit 46 determines whether or not it is necessary to correct the temperature of the pressure roller 31. If it is necessary to correct, the process proceeds to step S54. If it is not necessary to correct, the process proceeds to step S58.

[0101] If the determination is Yes in step S52, in step S54, the drive control unit 46 determines the amount of correction for correcting the temperature of the pressure roller 31. The process proceeds to step S56.

[0102] In step S56, the drive control unit 46 determines the control to drive the pressure roller 31 at the corrected temperature, and then the process ends.

[0103] If the result is No in step S52, the drive control unit 46 determines not to correct the temperature of the pressure roller 31.

[0104] The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the scope of the present invention. The drawings are mainly schematic illustrations of each component for ease of understanding, and the thickness, length, number, etc. of each component shown in the drawings are different from the actual ones due to the convenience of drawing. In addition, the materials, shapes, dimensions, etc. of each component shown in the above embodiments are merely examples, and are not particularly limited, and various modifications are possible within a scope that does not substantially deviate from the effects of the present invention. [Industrial Applicability]

[0105] The present invention can be used in the field of image forming apparatuses. [Explanation of symbols]

[0106] 3. Image forming equipment 16 Fixing device 40 Timing section 41 Temperature measurement section 42 Temperature information output section 43 Temperature characteristic calculation section 44 Guessing part 45 Storage section 46 Drive control unit 47 Pressure roller drive unit

Claims

1. An image forming apparatus including a fixing device, The fixing device is a fixing belt for heating and fixing the toner image transferred onto the sheet; a heater for heating the fixing belt; a pressure roller that rotates the fixing belt in contact with the fixing belt; having The image forming apparatus includes: A timekeeping unit that keeps track of multiple times; a temperature measuring unit for measuring a temperature of the heater or a temperature of the fixing belt at the plurality of times; a temperature information output unit that outputs heater temperature information or fixing belt temperature information based on the heater temperature or the fixing belt temperature at the plurality of times; a temperature characteristic calculation unit that outputs temperature characteristic information of the heater or the fixing belt based on the heater temperature information or the fixing belt temperature information; a drive control unit that outputs linear speed information for controlling a linear speed of the pressure roller based on the temperature characteristic information; a pressure roller driving unit that drives the pressure roller based on the linear speed information; Equipped with The timer unit measures a predetermined time after the fixing device stops, The drive control unit controls the pressure roller drive unit to drive the pressure roller based on the linear speed information only when a command to restart the drive is received within the predetermined time.

2. The timing unit measures a predetermined time after the fixing device stops, The image forming apparatus according to claim 1 , wherein the drive control unit invalidates the pressure roller temperature information when an instruction to restart the fixing device is not received within the predetermined time after the fixing device has stopped.

3. An image forming apparatus including a fixing device, The fixing device is a fixing belt for heating and fixing the toner image transferred onto the sheet; a heater for heating the fixing belt; a pressure roller that rotates the fixing belt in contact with the fixing belt; having The image forming apparatus includes: A timekeeping unit that keeps track of multiple times; a temperature measuring unit for measuring a temperature of the heater or a temperature of the fixing belt at the plurality of times; a temperature information output unit that outputs heater temperature information or fixing belt temperature information based on the heater temperature or the fixing belt temperature at the plurality of times; a temperature characteristic calculation unit that outputs temperature characteristic information of the heater or the fixing belt based on the heater temperature information or the fixing belt temperature information; a drive control unit that outputs linear speed information for controlling a linear speed of the pressure roller based on the temperature characteristic information; a pressure roller driving unit that drives the pressure roller based on the linear speed information; Equipped with The timer unit measures a predetermined time after the fixing device stops, The image forming apparatus, wherein the drive control unit invalidates pressure roller temperature information when an instruction to restart the fixing device is not received within the predetermined time after the fixing device has stopped.

Images