JP2010113256A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress overshoot phenomenon of the surface temperature of a fixing member (fixing roller 32) caused by the switching of a recording medium, in an image forming apparatus that fixes a toner image to a recording medium using a fixing member (fixing roller 32) heated by a heat source (heater 34). <P>SOLUTION: When a new target temperature range is set by a temperature setting section 63 accompanying the switching of a recording medium, a change rate of the surface temperature of the fixing member (fixing roller 32) detected by a temperature detecting section 61 is calculated. If the change rate exceeds a prescribed value or if the second-order differential of the surface temperature is positive, a power supply control section 64 controls so that power is not supplied to a heat source (heater 34) even if the present surface temperature is lower than the target temperature range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that fixes a toner image onto a recording medium by heat.

  The image forming apparatus usually has (1) a charging step for uniformly and uniformly charging the photosensitive drum, (2) an exposure step for exposing the surface of the photosensitive drum, and (3) charge of the exposed portion. A developing step of forming a toner image by forming an electrostatic latent image by erasing and forming a toner image; (4) a transfer step of transferring the toner image to a recording medium (printing paper, etc.); An image is formed (printed) on the recording medium by executing a fixing step of fixing the toner image to the recording medium by pressure or the like.

  In the fixing step, the temperature of the fixing device (particularly, the heating fixing member) that heats and presses the recording medium to which the toner image is adhered is within a predetermined temperature range that is set according to the type of recording medium and the printing speed. Energization control of a heat source such as a heater or a halogen lamp is performed so as to be maintained.

The most common method for controlling the temperature of a conventional fixing member is to detect the surface temperature of the fixing member using a temperature detecting element, and turn on the duty of the heat source (power source) according to the difference between the detected surface temperature and the target temperature. The ratio of the time during which the switch is turned on) was controlled. Patent Document 1 proposes a technique for measuring the heating characteristics when the apparatus is shifted from the power saving mode to the normal mode and the fixing member is warmed up, and correcting the lighting duty using the heating characteristics. Yes.
Japanese Patent Laying-Open No. 2005-338634 (paragraph “0006”, FIG. 1)

  However, in the above-described conventional fixing member temperature control method, for example, in a network printer, when switching of a recording medium occurs during printing and the target temperature range is set higher than before, the previous target temperature is set. Immediately after the final recording medium printed in the range passes through the fixing member, the temperature of the fixing member always rises due to the influence of the heat capacity, but the surface temperature detected during the rising is a newly set target temperature range When the temperature is lower, a warm-up process for increasing the temperature of the fixing member is executed, so that an overshoot phenomenon may occur in which the surface temperature exceeds the target temperature range.

  If the toner is fixed to the recording medium during this overshoot, the fixing performance deteriorates or the color characteristics change. Conventionally, after waiting until the surface temperature of the fixing member falls and enters the target temperature range. I was printing. For this reason, there is a disadvantage that the printing waiting time increases.

  The present invention has been made to solve the above-described problems, and reduces the printing waiting time by suppressing the occurrence of the overshoot phenomenon of the surface temperature of the fixing member that occurs when the recording medium is switched. An object of the present invention is to provide an image forming apparatus that can perform the above-described process.

  In order to solve the above problems, in the image forming apparatus of the present invention, a fixing member heated by a heat source, a temperature detection unit for detecting the temperature of the fixing member, and a type of the recording medium are set. The energization control unit controls the power supplied to the heat source so as to maintain the temperature detected by the temperature detection unit within the target temperature range. Power supply to the heat source until the temperature change rate (temperature change rate) detected by the temperature detection unit falls below a predetermined value after the target temperature range is set higher than before. It was controlled not to do it.

  Furthermore, in another image forming apparatus of the present invention, a fixing member heated by a heat source, a temperature detecting unit for detecting the temperature of the fixing member, and a target temperature range set corresponding to the type of the recording medium. And an energization control unit that controls power supplied to the heat source so as to maintain the temperature detected by the temperature detection unit, wherein the energization control unit corresponds to switching of the type of the recording medium. When the target temperature range is set higher than before and the temperature of the fixing member is rising due to the influence of the heat capacity, the change rate of the temperature change rate detected by the temperature detection unit, that is, the second-order differential value Until the temperature becomes 0 or less, the power is not supplied to the heat source, and when the second-order differential value becomes 0 or less, the temperature is detected by the temperature detector and the rate of change thereof. It predicted, based on the maximum temperature of the fixing member in the expected arrival time of the recording medium, and to control the supply power to the heat source.

  According to the image forming apparatus of the present invention, the occurrence of the overshoot phenomenon of the surface temperature of the fixing member accompanying the switching of the recording medium can be suppressed, so that the printing waiting time can be shortened.

  Furthermore, according to another image forming apparatus of the present invention, since the maximum temperature of the fixing member at the estimated arrival time of the recording medium is predicted and the power supplied to the heat source is controlled, the printing waiting time can be further shortened.

[Embodiment 1]
FIG. 1 is a cross-sectional structure diagram of mechanical components included in a printer 1 according to a first embodiment of an image forming apparatus according to the present invention.

  As shown in FIG. 1, the printer 1 mainly includes a medium cassette 3, 4, an image forming unit 11, 12, 13, 14, a transfer belt unit 20, a fixing device 30, and a pickup. A medium conveying mechanism including rollers 40 and 41, registration roller pairs 42 and 43, and a discharge roller pair 44, and a write sensor 50, a discharge sensor 51, and a stack sensor for detecting the conveyance of the recording medium. 52 and a control unit 601 (see FIG. 3) for controlling these units. Details of the control unit 601 will be described later.

  In FIG. 1, a recording medium 2 is a medium on which an image is printed, such as paper before printing or OHP. The medium cassette 3 is a tray that stores the recording medium 2 described above. The media cassette 4 is a media cassette attached to the printer 1. The recording medium 5 is a different type of medium from the recording medium 2, and paper, OHP, or the like having a different size or type from the recording medium 2 is assumed and stored in the medium cassette 4. The recording medium 7 is a recording medium that is discharged after printing is completed.

  The image forming units 11, 12, 13, and 14 are units for forming toner images typified by cyan, magenta, yellow, and black developers, respectively.

  The transfer belt unit 20 includes transfer rollers 21, 22, 23, and 24. The transfer rollers 21, 22, 23, and 24 are provided with toner on the recording media 2 and 5 when the recording media 2 and 5 pass between the image forming units 11, 12, 13, and 14 and the transfer belt unit 20. A roller for transferring an image. The fixing device 30 is a unit component that fixes the transferred toner image to the recording media 2 and 5, and is removable from the printer 1.

The fixing device 30 includes a temperature detection element 31, a fixing roller 32 as a fixing member, and a pressure roller 33, as shown in a perspective view in FIG. The fixing roller 32 incorporates a heater 34 as a heat source typified by a halogen lamp, and is mounted in pressure contact with the pressure roller 33. The fixing roller 32 and the pressure roller 33 have gears (not shown) and are driven to rotate by a unit drive gear (not shown).
In this embodiment, the fixing roller 32 is used as an example of the fixing member. However, the fixing member may be an endless belt with a built-in heat source. The pressure roller 33 side may also be a combination of an endless belt and a pressing member that presses the belt from the inside toward the fixing member.

  The temperature detecting element 31 is installed in the vicinity of the fixing roller 32 or in a state in contact with the fixing roller 32 in order to detect the surface temperature of the fixing roller 32. As the temperature detection element 31, for example, a thermistor whose resistance value changes with temperature is used, and a temperature detection unit 61 (see FIG. 3) described later fixes by taking in a voltage signal that has been subjected to A / D (Analog to Digital) conversion. The surface temperature of the roller 32 is detected.

  Returning to FIG. The pickup roller 40 is a roller for pulling out the recording medium 2 from the medium cassette 3, and the pickup roller 41 is a roller for pulling out the recording medium 5 from the medium cassette 4. The registration roller pair 42 is provided in pressure contact with each other with the recording media 2 and 5 interposed therebetween, and the registration roller pair 43 is provided in pressure contact with each other with the recording media 2 and 5 interposed therebetween. The discharge roller pair 44 is a roller for discharging the recording media 2 and 5 that have been fixed, and is provided in pressure contact with each other.

The write sensor 50, the discharge sensor 51, and the stack sensor 52 are all mechanical sensors that recognize the passage of the recording media 2 and 5 in the respective conveyance paths.
The stack sensor 52 as a sensor for detecting that the recording medium has passed through the fixing member is a mechanical sensor for recognizing that the recording media 2 and 5 are ejected from the apparatus. It can be substituted by adding a delay time to the detection result by the sensor 51, and is not essential.

FIG. 3 is a block diagram showing an internal configuration of the control unit 601 accommodated in the printer 1 according to the first embodiment of the present invention.
As shown in FIG. 3, the control unit 601 is configured by, for example, a microprocessor with a built-in memory, and includes a temperature detection unit 61, a temperature change rate calculation unit 62, a temperature setting unit 63, an energization control unit 64, Consists of. The temperature detection unit 61, the temperature change rate calculation unit 62, the temperature setting unit 63, and the energization control unit 64 described above are all described below by the microprocessor sequentially reading and executing the program recorded in the memory. Each of the functions to be executed is executed.

  The temperature detection unit 61 holds a voltage / temperature conversion table in which the relationship between the voltage and the temperature is preset and registered, converts the voltage detected by the temperature detection element 31 into a temperature, and converts the temperature into a fixing roller. It outputs to the temperature change rate calculation part 62 as 32 surface temperature. The temperature change rate calculation unit 62 calculates the temperature change rate from the current temperature output from the temperature detection unit 61 and the temperature output immediately before, and outputs the temperature change rate to the energization control unit 64. The temperature setting unit 63 holds a target temperature table in which the temperature to be targeted for each type of recording medium and printing speed is set and registered in advance, and recognizes the type and printing speed of the recording medium included in the print command. Then, the target temperature corresponding to them and the target temperature range consisting of the upper limit and the lower limit temperature are read from the target temperature table, and the target temperature and the target temperature range are output to the energization control unit 64.

The energization control unit 64 compares the current temperature output from the temperature detection unit 61 with the target temperature range output from the temperature setting unit 63, and if the current temperature is lower than the target temperature range, the current temperature is set to the target temperature. The energization of the heater 34 is turned on so as to approach, and a warm-up process for increasing the surface temperature of the fixing roller 32 is performed. In addition, when the current temperature is higher than the target temperature range, the energization control unit 64 performs cool-down control for turning off the energization of the heater 34 so as to approach the target temperature and lowering the surface temperature of the fixing roller 32. .
The energization control unit 64 monitors the temperature change rate output from the temperature change rate calculation unit 62, and when the temperature change rate is equal to or higher than a predetermined value, the temperature of the fixing roller 32 is lower than the target temperature range. However, the heat source (heater 34) is controlled not to be energized.

FIG. 4 is a flowchart showing the operation of the control unit 601 shown in FIG. Hereinafter, the operation of the control unit 601 will be described in detail with reference to the flowchart shown in FIG.
First, the control unit 601 determines whether or not the temperature setting unit 63 has a print command (step S401). If there is no print command (step S401 “No”), the power supply control mode of the power supply control unit 64 is set to the standby control mode. (Step S402).
On the other hand, when there is a print command (step S401 “Yes”), the temperature setting unit 63 refers to the target temperature table and includes a target temperature (for example, Tm1) corresponding to a printing condition and an upper limit and a lower limit temperature. The target temperature range is read, and the target temperature and the target temperature range are output to the energization control unit 64 (step S403).

  Next, the energization controller 64 determines whether the current surface temperature of the fixing roller 32 detected by the temperature detector 61 is within the target temperature range output from the temperature setting unit 63 and is in a printable state. It is determined whether or not (step S404). If it is determined that printing is not possible (step S404 “No”), the energization control unit 64 repeats warm-up or cool-down processing until the surface temperature of the fixing roller 32 falls within the target temperature range. When it is determined that the surface temperature of the fixing roller 32 falls within the target temperature range and printing is possible (step S405), the energization control unit 64 is shifted to the print control mode to execute the printing process (step S405). Step S406). In this print control mode, the energization control unit 64 monitors the surface temperature of the current and past fixing rollers 32 until a series of fixing operations to a recording medium is completed, for example, and detects PID (Proportional-Integral-). By controlling the lighting duty of the heat source (heater 34) by Derivative control, the surface temperature is maintained within the above range.

When the execution of the printing process is completed, the temperature setting unit 63 determines whether or not there is a next print command (step S407). If there is no next command (step S407 “No”), the temperature control unit 64 sets the energization control unit 64 in the standby control mode. (Step S408), the process returns to the beginning and waits for the next print command.
On the other hand, if there is a next print command (step S407 “Yes”), the temperature setting unit 63 determines whether or not the target temperature is switched according to the change in the type of recording medium and the printing speed (step S409), and the target temperature. If there is no switching (step S409 “No”), the process returns to step S406 to cause the energization control unit 64 to shift to the print control mode. When the target temperature is switched (step S409 “Yes”), the output of the stack sensor 52 is monitored to confirm that the final recording medium has been discharged, and then a new target temperature (for example, Tm2) and target temperature are detected. The range is output to the energization control unit 64 (step S410).

Next, the temperature change rate calculation unit 62 calculates the temperature change rate from the current temperature detected by the temperature detection unit 61 and the immediately preceding temperature, and outputs the temperature change rate to the energization control unit 64. It is determined whether or not the temperature change rate output from the change rate calculation unit 62 is less than a predetermined value (St) (step S411). Here, when it is determined that it is not less than the predetermined value (step S411 “No”), the energization control unit 64 turns off the energization of the heater 34 (step S412), and the surface temperature of the fixing roller 32 is overshot. prevent.
On the other hand, when it is determined that the temperature change rate is less than the predetermined value (St) (step S411 “Yes”), the energization control unit 64 returns to step S404 and executes the above-described processing.

  FIG. 5 is a time chart showing an operation example of the image forming apparatus (printer 1) according to the first embodiment of the present invention. FIG. 5A shows a period from the start of printing until the target temperature is switched and printing is completed. (B) surface temperature change rate of the fixing roller 32, (c) energization signal of the heater 34, (d) output signal of the stack sensor 52, (e) energization control mode of the energization control unit 64, Each of them is shown.

In the time chart of FIG. 5, at time T201, the energization control unit 64 shifts from the standby control mode to the print control mode by a print command.
Here, it is assumed that the target temperature Tm1 output by the temperature setting unit 63 is, for example, 170 ° C., similarly to the target temperature in the standby state (step S403 in FIG. 4). At time T201, the current temperature detected by the temperature detection unit 61 is within a target temperature range composed of an upper limit temperature (for example, 185 ° C.) and a lower limit temperature (for example, 160 ° C.) set with reference to the target temperature Tm1. Therefore, the process immediately shifts to the print control mode and print processing for a series of recording media is executed (step S406 in FIG. 4).

Next, it is assumed that the temperature setting unit 63 switches the target temperature in response to the next print command at time T202 and sets the target temperature Tm2 (for example, 180 ° C.) in the energization control unit 64 (step in FIG. 4). S410).
The temperature change rate calculation unit 62 calculates a temperature change rate from the immediately preceding temperature detected by the temperature detection unit 61 and the current temperature and outputs the temperature change rate to the energization control unit 64. The energization control unit 64 calculates the temperature change rate. It is determined whether or not the temperature change rate output from the unit 62 is less than a predetermined value St (for example, 1 ° C./s) (step S411 in FIG. 4). In this example, since it exceeds the predetermined value St (1 ° C./s), the power supply to the heat source (heater 34) is turned off (step S412 in FIG. 4). That is, the energization control unit 64 performs control so that the heater 34 is not energized even if the current temperature is lower than the target temperature Tm2.

  Next, when it is determined at time T203 that the temperature change rate calculated by the temperature change rate calculating unit 62 is less than the predetermined value St (1 ° C./s), is the detected temperature within the target temperature range? In this example, since the current temperature is within the target temperature range, the energization control unit 64 shifts to the print control mode and print processing is executed (in FIG. 4). In step S406), the recording media 2 and 5 to which the toner image has been transferred at time T204 are carried into the fixing device 30, and the toner is fixed to the recording media 2 and 5 by heat and pressure.

  As described above, during the period from time T202 when the temperature change rate exceeds the predetermined value (St) to time T203, the energization control unit 64 turns off the energization of the heater 34, thereby the surface temperature of the fixing roller 32. Overshoot is suppressed.

[Embodiment 2]
Since the mechanism of the printer and the mechanism of the fixing unit according to the second embodiment of the image forming apparatus according to the present invention are the same as those of the printer 1 according to the first embodiment shown in FIG. 1 and FIG. The description will be omitted, focusing on differences from the first embodiment.

  FIG. 6 is a block diagram illustrating an internal configuration of the control unit 602 accommodated in the printer according to the second embodiment of the image forming apparatus of the present invention. As can be seen by comparing FIG. 6 and FIG. 3, the control unit 602 shown in FIG. 6 has a temperature change rate comparison calculation unit 65 added to the control unit 601 according to the first embodiment shown in FIG. It has a configuration. The temperature change rate comparison calculation unit 65 calculates the change rate of the temperature change rate, that is, the second-order differential value of the surface temperature, from the temperature change rate calculated immediately before by the temperature change rate calculation unit 62 and the current temperature change rate. And output to the energization control unit 64. The energization control unit 64 controls the heater 34 using the second-order differential value output from the temperature change rate comparison calculation unit 65. Since other components are the same as those in the first embodiment, description thereof is omitted.

  The operation of the control unit 602 is obtained by changing a part of the operation of the control unit 601 shown in FIG. FIG. 7 shows only a flowchart of the changed part. Hereinafter, the operation of the changed portion of the control unit 602 will be described in detail with reference to the flowcharts shown in FIGS. 4 and 7.

  When the target temperature is changed to Tm2 in step S410 of FIG. 4, next, the energization control unit 64 determines whether the second-order differential value of the surface temperature output from the temperature change rate comparison calculation unit 65 is 0 or less. Determination is made (step S701). If the value is not 0 or less (“No” in step S701), the cool-down process is repeatedly executed until the value becomes 0 or less (step S702). If the value is 0 or less (step S701 “Yes”), the energization control unit 64 detects the current temperature detected by the temperature detection unit 61 and the current temperature output from the temperature change rate calculation unit 62. Based on the change rate, the maximum value of the surface temperature of the fixing roller 32 when the recording medium reaches the fixing device 30 is predicted, and it is determined whether or not the value is within the target temperature range (step S703). ). That is, the energization control unit 64 determines the printability after waiting for the increase in the temperature change rate of the surface temperature of the fixing roller 32 to end.

  At this time, the reason for waiting for the rise of the temperature change rate to end is that the actual temperature will not be higher when the maximum temperature after a predetermined time elapses is predicted from the current temperature change rate. It is to do.

  If the predicted maximum value of the surface temperature is not within the target temperature range (step S703 “No”), the warm-up or cool-down process is repeatedly executed until the value falls within the target temperature range (step S704). If the predicted maximum value of the surface temperature is within the target temperature range (step S703 “Yes”), it is determined that printing is possible and the print control mode is entered to execute the printing process (FIG. 4). Step S406), the same processing is repeated thereafter.

  In determining the printability, instead of predicting the maximum temperature when the recording medium reaches the fixing device 30 from the current temperature of the fixing roller 32 and the rate of temperature change, it is measured in advance. The maximum temperature may be predicted using the temperature change characteristic of the fixing roller 32 with respect to the time axis. In addition, there is a method to determine the printability by predicting the future temperature change rate from the past and current temperature change rates, but here we omit the process of predicting the future temperature change rate and simplify the control. Yes.

  FIG. 8 is a time chart showing an operation example of the image forming apparatus according to the second embodiment of the present invention. (A) From the start of printing until the target temperature is switched and the printing is completed. (B) surface temperature change rate of fixing roller 32, (c) second-order differential value of surface temperature of fixing roller 32, (d) energization signal of heater 34, (e) output signal of stack sensor 52, (f ) Each of the energization control modes of the energization control unit 64 is shown.

  In the time chart of FIG. 8, the control unit 602 first assumes that the temperature setting unit 63 switches the target temperature at time T301 and sets the target temperature Tm2 (for example, 180 ° C.) in the energization control unit 64 (FIG. 8). Step S410 of 4).

  Next, since the second-order differential value of the surface temperature calculated by the temperature change rate comparison calculation unit 65 is not less than or equal to 0, the energization control unit 64 performs a cool-down process (step S702 in FIG. 7), and the time T302 When the second-order differential value becomes 0 or less, the maximum value of the surface temperature when the recording media 2 and 5 are carried into the fixing device 30 is predicted, and this value is the upper limit temperature (for example, 195 ° C.) of the target temperature range. Since it is determined that it is below (step S703 “Yes”), the energization control mode is shifted to the print control mode and the printing process is started immediately (step S406 in FIG. 4).

  Thereafter, at time T303, the recording media 2 and 5 on which the toner images are transferred are carried into the fixing device 30, and are fixed by heat and pressure.

  As described above, the energization control unit 64 executes the cool-down process from time T301 to time T302 when the second-order differential value of the surface temperature is positive, thereby turning off the energization to the heater 34. Overshooting of the surface temperature of the fixing roller 32 is suppressed.

  Note that all the functions of the control units 601 and 602 shown in FIGS. 3 and 6 may be realized by software, or at least a part thereof may be realized by hardware.

  For example, the energization controller 64 calculates the rate of change of the surface temperature detected by the temperature detector 61, and when the rate of temperature change is equal to or greater than a predetermined value, the surface temperature of the fixing roller 32 has reached the target temperature range. Data processing for controlling the heater 34 not to be energized without it may be realized on a computer by one or a plurality of programs, or at least a part thereof may be realized by hardware.

  In the image forming apparatus according to the first and second embodiments of the present invention, the application example to the printer has been described. However, the present invention is not limited to the printer, but is similarly applied to an MFP (Multi Function Peripheral), a facsimile, and a copying apparatus. It can be applied to.

1 is a cross-sectional structure diagram of an image forming apparatus (printer) according to Embodiment 1. FIG. FIG. 3 is a perspective view illustrating a structure of a fixing unit included in the image forming apparatus (printer). FIG. 3 is a block diagram illustrating an internal configuration of a control unit according to the first embodiment. 3 is a flowchart illustrating an operation of a control unit according to the first embodiment. 3 is a time chart illustrating an operation of the image forming apparatus (printer) according to the first exemplary embodiment. 6 is a block diagram illustrating an internal configuration of a control unit according to Embodiment 2. FIG. 10 is a flowchart illustrating an operation of a control unit according to the second embodiment. 6 is a time chart illustrating an operation of the image forming apparatus (printer) according to the second exemplary embodiment.

Explanation of symbols

1 Printer (image forming device)
2, 5, 7 Recording medium 30 Fixing device 32 Fixing roller (fixing member)
34 Heater (heat source)
52 Stack sensor (sensor)
61 Temperature detection unit 62 Temperature change rate calculation unit 63 Temperature setting unit 64 Energization control unit 65 Temperature change rate comparison calculation unit 601 602 Control unit

Claims (5)

A fixing member heated by a heat source;
A temperature detector for detecting the temperature of the fixing member;
In an image forming apparatus having an energization control unit for controlling power supplied to the heat source so as to maintain a temperature detected by the temperature detection unit within a target temperature range set corresponding to the type of recording medium.
The energization control unit
In response to the switching of the type of the recording medium, power is supplied to the heat source until the rate of change in temperature detected by the temperature detection unit falls below a predetermined value after the target temperature range is set higher than before. An image forming apparatus that is controlled so as not to be performed. A sensor for detecting that the recording medium has passed through the fixing member;
The energization control unit
2. The image forming apparatus according to claim 1, wherein when the preceding recording medium detects that the preceding recording medium has passed through the fixing member, the target temperature range corresponding to the type of the succeeding recording medium is set. . A fixing member heated by a heat source;
A temperature detector for detecting the temperature of the fixing member;
In an image forming apparatus having an energization control unit for controlling power supplied to the heat source so as to maintain a temperature detected by the temperature detection unit within a target temperature range set corresponding to the type of recording medium.
The energization control unit
Supplying power to the heat source until the second-order differential value of the temperature detected by the temperature detection unit becomes 0 or less after the target temperature range is set higher than before in response to the switching of the type of the recording medium An image forming apparatus that is controlled so as not to perform the process. The energization control unit
When the second-order differential value of the temperature detected by the temperature detection unit becomes 0 or less after the target temperature range is set higher than before in response to the switching of the type of the recording medium,
Based on the maximum temperature of the fixing member at the estimated arrival time of the recording medium predicted by the temperature detected by the temperature detection unit and the rate of change thereof,
The image forming apparatus according to claim 3, wherein power supplied to the heat source is controlled. A sensor for detecting that the recording medium has passed through the fixing member;
The energization control unit
5. The target temperature range corresponding to the type of a subsequent recording medium is set when the preceding recording medium detects that the preceding recording medium has passed through the fixing member by the sensor. Image forming apparatus.

Images