JP6428251B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus that forms a toner image and forms an image by transferring the formed toner image to a recording medium. More specifically, the present invention relates to an image forming apparatus having a fixing unit that heats a recording medium that has received a toner image.

  In an image forming apparatus using toner, a toner image is formed on an image carrier, recorded on a recording medium, and then the recording medium is heated to fix the image. Such an image forming apparatus has been described in Japanese Patent Application Laid-Open No. H10-228707. Patent Document 1 discloses a configuration of a fixing unit that heats a pressure roller and a fixing roller.

JP 2014-153682 A

  However, the conventional image forming apparatus has the following problems. That is, the transfer may be insufficient depending on the use situation. There was such a case immediately after long-term rest, especially when the power was turned on. The reason is that the temperature of the transfer portion is low and the resistance is high. This was particularly noticeable when the usage conditions were low-temperature environments. On the other hand, conventionally, the transferability is ensured by waiting until the transfer portion is warmed or by reducing the line speed. Therefore, productivity is sacrificed.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of improving transferability by quickly heating a transfer portion when the transfer portion is at a low temperature. It is.

An image forming apparatus according to the first or second aspect of the present invention, which has been made for the purpose of solving this problem, includes a toner image carrier that carries a toner image, and a toner image that forms a toner image on the toner image carrier. A forming unit, a transfer member that transfers a toner image on the toner image carrier to a recording medium at a position other than a position where the toner image forming unit is formed, and a recording medium that has received the transfer of the toner image by the transfer member The image forming apparatus having a pair of fixing rollers for fixing the toner image on the recording medium has an air duct that generates an air flow from the pair of fixing rollers toward the transfer position by the transfer member.

  In this image forming apparatus, a toner image is formed on the toner image carrier by the toner image forming unit. The toner image is transferred to the recording medium by the transfer member at a position other than the position where the toner image forming unit forms. Then, the recording medium that has received the transfer of the toner image is heated by the pair of fixing rollers, whereby the toner image is fixed on the recording medium. Thus, an image is formed on the recording medium. In this image forming apparatus, in addition to the above-described image forming operation, it is possible to perform a heating operation for heating the transfer member when the temperature is low. In other words, an air flow from the pair of fixing rollers to the transfer position by the transfer member is caused by the air duct. By performing the air blowing by this air duct while heating the fixing roller pair, the temperature of the transfer member can be raised to an appropriate temperature at an early stage. By performing an image forming operation on that, it is possible to perform a good image formation without a transfer defect with a small waiting time.

The image forming apparatus according to the above aspect further includes a normal arrangement in which the transfer member is pressed against the toner image carrier and the fixing roller pair is in contact with each other, and the transfer member is separated from the toner image carrier and the fixing roller pair is An operation control unit that switches between separate heating arrangements is provided. The operation control unit arranges the transfer member and the fixing roller pair in a normal arrangement during image formation, and adds the transfer member and the fixing roller pair in a heating operation. temperature when the arrangement, the heating of the fixing roller pair is turned on, Ru der those causing airflow through the air duct.

  In this image forming apparatus, the operation control unit presses the transfer member against the toner image carrier and the fixing roller pair comes into contact with each other, and the transfer member is separated from the toner image carrier and the fixing roller pair is also separated. Switching to the heating arrangement is performed. Then, image formation is performed at the time of normal arrangement. Further, during the heating operation, image formation is not performed and the transfer member is warmed.

In the image forming apparatus according to the first aspect among the above, the air duct is further on the downstream side of the pair of fixing rollers in the recording medium conveyance direction and on the toner image carrier side with respect to the conveyance path of the recording medium. And the normal state in which airflow is blown from the discharge port to the nip part of the fixing roller pair during normal arrangement, and the heating that has been moved to bring the discharge port closer to the recording medium transport path compared to the normal state it is intended to take a state when the operation control unit, the air duct, at the time of image formation with a normal state, at the time of warming operation in which the time-state heating.

  In this image forming apparatus, the air blowing duct blows an air flow from the discharge port to the nip portion of the fixing roller pair at the time of normal arrangement, and in the warmed state, the discharge port is brought closer to the conveyance path of the recording medium than in the normal state. An air stream is blown toward the transfer member to warm the transfer member.

Among the above, the image forming apparatus according to the second aspect further includes a temperature sensor that outputs a detection value indicating the temperature of the transfer member, and the operation control unit has an event corresponding to a predetermined heating operation start event. there was a warming operation starts when, Ru der shall terminate the heating operation when it reaches the target value detected value of the temperature sensor is predetermined.

  In this image forming apparatus, the target temperature of the heating operation is set in advance in the control unit, and the heating operation is performed until the detection value of the temperature sensor reaches the target temperature. finish.

  In the image forming apparatus according to the above aspect, the air duct is further divided into a plurality of sections in the width direction of the recording medium, and an air flow can be discharged for each section. The heating force can be adjusted for each section in the width direction, the temperature sensor is provided in the width direction range corresponding to the section of the air duct, and the operation control unit is provided for each section of the air duct. It is desirable to perform the heating operation.

  In this image forming apparatus, an air flow is discharged for each section in the width direction of the recording medium. Further, the fixing roller pair can adjust the heat generation force for each section in the width direction of the recording medium, and the air duct can also blow the air for each section, so that the temperature of the secondary transfer roller 11 can be uniformly targeted in the axial direction. It can be higher than the temperature.

  According to the above aspect, the present invention provides an image forming apparatus capable of improving transferability by rapidly heating the transfer portion when the transfer portion is at a low temperature.

1 is an overall configuration diagram of an image forming apparatus according to a first embodiment and a second embodiment. FIG. 4 is a layout diagram of a fixing device and a secondary transfer roller in a normal state according to the first embodiment and the second embodiment. FIG. 5 is a layout diagram of a fixing device and a secondary transfer roller during a heating operation of a secondary transfer roller according to the first embodiment and the second embodiment. It is an arrangement plan of a ventilation duct concerning a 2nd embodiment, and a temperature sensing element.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
This embodiment embodies the present invention in an electrophotographic image forming apparatus. FIG. 1 shows a schematic configuration of an image forming apparatus 1 in which the present exemplary embodiment is arranged. The image forming apparatus 1 mainly includes an image forming unit 2, a scanner unit 40, and a control unit 60.

  The scanner unit 40 includes a document device table 42 and an automatic document feeder 41. Thus, the scanner unit 40 acquires the image data while automatically and sequentially transporting the document placed on the document device table 42 by the automatic document feeder 41. Based on the image data acquired by the scanner unit 40, the image forming unit 2 forms an image.

  The image forming unit 2 includes an intermediate transfer belt 7 and a process unit 14. The intermediate transfer belt 7 is an endless belt member having electrical conductivity. The intermediate transfer belt 7 is supported by rollers 26 and 27 at two upper end portions. Rollers 28 and 29 are also arranged at two locations on the lower end portion of the intermediate transfer belt 7. During image formation, these rollers 26, 27, 28, and 29 are driven to rotate clockwise. As a result, the intermediate transfer belt 7 is driven to rotate.

  The process unit 14 forms a toner image having a predetermined density on the belt surface of the intermediate transfer belt 7 that moves at a predetermined speed. The process unit 14 includes an image forming unit 10Y that forms a yellow (Y) image, an image forming unit 10M that forms a magenta (M) image, and an image forming unit that forms a cyan (C) image. 10C and an image forming unit 10K that forms a black (K) color image.

  The image forming unit 10Y has a photoreceptor 3Y. In addition, the image forming unit 10Y includes a charging unit 4Y, an optical writing unit 5Y, a developing device 6Y, and a cleaning unit 9Y that are arranged around the photoreceptor 3Y. The other image forming units 10M, 10C, and 10K are configured similarly to the image forming unit 10Y. In the following description, Y, M, C, and K are not attached unless they are distinguished.

  In the image forming unit 10, the charging unit 4 charges the surface of the photoreceptor 3. The optical writing unit 5 exposes the charged photoreceptor 3 based on the image data. Thereby, an electrostatic latent image based on the image data is formed on the photoreceptor 3. The developing device 6 develops this electrostatic latent image. As a result, a toner image which is a visible image is formed on the photoreceptor 3.

  In this way, toner images of the respective colors are formed on the photoreceptors 3Y, 3M, 3C, and 3K. The toner images of the respective colors formed on the photoreceptor 3 are transferred to the intermediate transfer belt 7 by primary transfer rollers 8Y, 8M, 8C, and 8K provided corresponding to the photoreceptors 3Y, 3M, 3C, and 3K. This is called “primary transfer”.

  The toner image formed on the intermediate transfer belt 7 is sequentially transferred toward the secondary transfer roller 11 by rotating the intermediate transfer belt 7 in the clockwise direction in FIG. 1 according to the rotation of the plurality of rollers 26, 27, 28, and 29. Sent. The secondary transfer roller 11 is disposed below the intermediate transfer belt 7 in the drawing.

  Further, the image forming apparatus 1 includes a paper supply unit 15. The paper supply unit 15 includes a supply tray for storing printing paper. The paper P supplied by the paper supply unit 15 is conveyed to the secondary transfer roller 11 through the loop roller 22 and the registration roller 23.

  The toner image formed on the intermediate transfer belt 7 is collectively transferred from the intermediate transfer belt 7 to the paper P by the secondary transfer roller 11. This is called secondary transfer. A fixing device 17 is provided on the left side of the secondary transfer roller 11 in the paper transport path. The fixing device 17 includes a heating roller 300, a fixing roller 301, and a pressure roller 302. The fixing device 17 performs a fixing process of the color image transferred to the paper P by applying pressure while heating the paper P by the fixing roller 301 and the pressure roller 302 forming a pair of fixing rollers. The sheet after fixing is discharged through the paper discharge roller 20 and the discharge roller 24. Note that the image forming apparatus 1 is capable of duplex printing as well as simplex printing. A cleaning unit 12 is provided at the upper left of the intermediate transfer belt 7.

  FIG. 2 is a detailed view of the arrangement of the fixing device 17 and the secondary transfer roller 11 among the above. The fixing device 17 includes a heating roller 300, a fixing roller 301, a pressure roller 302, a fixing belt 303, a fixing lamp 200, a fixing lamp 250, and a paper discharge roller 20. The secondary transfer roller 11 is pressed against the roller 28. Between the fixing roller 301 and the pressure roller 302, the paper P carrying unfixed toner is conveyed along the passage path S. Further, the air duct 100 is on the downstream side of the fixing roller 301 and the pressure roller 302 in the transport direction of the paper P and is on the intermediate transfer belt 7 side with respect to the transport path of the paper P. Further, the air duct 100 is disposed between the heating roller 300 and the discharge roller 24. The blower duct 100 is provided with a blower fan 160 that sucks outside air. In addition, an air outlet 170 is formed in the air duct 100. The air outlet 170 is at the lower end of the air duct 100 in the drawing and faces the fixing device 17 side. In addition, a temperature detection element 400 is disposed in the vicinity of the secondary transfer roller 11.

  In the fixing device 17, a fixing belt 303 as a fixing member is stretched around a fixing roller 301 as a driving roller and a heating roller 300 as a driven roller, and rotates. The pressure roller 302 is provided to face the fixing roller 301 via the fixing belt 303. The pressure roller 302 is pressed against the fixing roller 301 via the fixing belt 303.

A fixing lamp 200 as a heating unit is installed on the shaft portion of the heating roller 300. The heating roller 300 is heated when the fixing lamp 200 is turned on, and the fixing belt 303 is heated by the heating roller 300. In addition, in the shaft portion of the pressure roller 302,
A fixing lamp 250 as a heating unit is installed, and the pressure roller 302 is heated by turning on the fixing lamp 250.

  In the configuration of FIG. 2, the sheet P carrying unfixed toner passes through the nip portion between the fixing belt 303 and the pressure roller 302 during image formation. The paper P passing through the nip part is melted by heating and pressurizing. The melted toner is fixed on the paper P. The blower duct 100 sucks outside air when the blower fan 160 is turned on. Thereby, air is discharged from the air outlet 170 of the air duct 100. The discharged air flows toward the nip portion between the fixing belt 303 and the pressure roller 302. The sheet P on which the toner is fixed is separated from the fixing belt 303 by the air blowing from the air blowing port 170. The separated paper P is sent out of the apparatus main body by the paper discharge roller 20.

  Next, the arrangement during the heating operation of the secondary transfer roller 11 in this embodiment will be described. The temperature of the secondary transfer roller 11 is low immediately after a long pause such as when the power is turned on. This state is defined as a heating operation start event. For this reason, the problem of secondary transfer failure occurs as described above. In such a case, the secondary transfer roller 11 needs to be heated, and the secondary transfer unit is heated prior to the normal operation. In the heating operation, the arrangement of the air duct 100, the pressure roller 302, and the secondary transfer roller 11 is changed from the arrangement shown in FIG. This is shown in FIG. Note that FIG. 2 shows a normal arrangement.

  In the arrangement of FIG. 3, the air outlet 170 of the air duct 100 is located between the fixing roller 301 and the pressure roller 302. This is the direction in which the air outlet 170 is brought closer to the recording medium conveyance path with respect to FIG. It has been moved to. In addition, the pressure roller 302 is disposed at a position away from the fixing roller 301. The secondary transfer roller 11 is also arranged at a position away from the intermediate transfer belt 7. The secondary transfer roller 11 in this state is released from being pressed against the intermediate transfer belt 7.

  The operation in the arrangement of FIG. 3, that is, the heating operation of the secondary transfer roller 11 will be described. In this operation, the fixing lamp 200, the fixing lamp 250, and the blower fan 160 are turned on. A target temperature of the secondary transfer roller 11 is set in the control unit 60. The target temperature is a lower limit temperature that is sufficiently high so as not to cause a problem of transfer failure during secondary transfer. The fixing lamp 200, the fixing lamp 250, and the blower fan 160 are feedback controlled by the control unit 60. Further, the fixing belt 303 also rotates when the fixing roller 301 is driven. The fixing belt 303 is heated via the heating roller 300 when the fixing lamp 200 is turned on. The pressure roller 302 is heated when the fixing lamp 250 is turned on. Further, when the blower fan 160 of the blower duct 100 is turned on, air is discharged from the blower port 170. The air discharged from the blower port 170 flows in the direction of arrow D, that is, toward the secondary transfer roller 11. On the way, the discharged air is heated between the pressure roller 302 and the fixing belt 303. Accordingly, the heated air hits the secondary transfer roller 11. Thereby, the secondary transfer roller 11 is heated. In this operation, the secondary transfer roller 11 and the intermediate transfer belt 7 are always rotated in order to suppress temperature nonuniformity in the rotation direction.

  In FIG. 3, the heating operation ends when the temperature of the secondary transfer roller 11 becomes equal to or higher than the target temperature. Specifically, when the temperature detected by the temperature detection element 400 reaches the target temperature, the heating operation is terminated. When the heating operation is finished, the air duct 100 and the pressure roller 302 return to the arrangement of FIG. 2 which is a normal state. As a result, a satisfactory image can be formed without a problem of transfer failure.

  In the first embodiment, the above operation is executed in the situation described below. First, the user turns on the power of the image forming apparatus 1. Also, when the user opens the front door of the image forming apparatus 1 and then closes the door, or when the image forming apparatus 1 returns from the sleep state. Furthermore, it is when the standby before printing of the image forming apparatus 1 is completed. Therefore, these events may be determined as heating operation start events.

[Second Embodiment]
Next, a second embodiment will be described. The image forming apparatus according to the second embodiment has the same general configuration as that of the first embodiment shown in FIG. The difference between 1st Embodiment and 2nd Embodiment exists in the detail of a ventilation duct. As shown in FIG. 4, the air duct 110 according to the second embodiment has partition walls 501 and 502 inside. In FIG. 4, the left-right direction is the axial direction of the secondary transfer roller 11. In addition, when the air duct 110 is seen from the front, it is the same as the air duct 100 of FIG. 3 of 1st Embodiment. The interior of the air duct 110 is divided into regions 1 and 3 at both ends in the axial direction of the secondary transfer roller 11 and a region 2 at the center by the partition walls 501 and 502. In the second embodiment, the air duct 110 has air outlets 171, 172, and 173 in each of the regions 1, 2, and 3, and these correspond to the air outlet 170 of the first embodiment. Further, the blower duct 110 has blower fans 161, 162, and 163 in each of the regions 1, 2, and 3, and these correspond to the blower fan 160 of the first embodiment.

  In the vicinity of the secondary transfer roller 11 in FIG. 4 of the second embodiment, temperature detection elements 401, 402, and 403 are provided in the regions 1, 2, and 3, respectively. These correspond to the temperature detection element 400 of the first embodiment. Fixing lamps 251, 252, and 253 are provided on the shaft portion of the pressure roller 302 in the regions 1, 2, and 3 of the second embodiment, respectively. These correspond to the fixing lamp 250 of the first embodiment. The air duct 110 has the expansion / contraction function shown in FIGS. 2 and 3 of the first embodiment. Further, as the air duct 110 expands and contracts, the arrangement of the pressure roller 302 and the secondary transfer roller 11 is also changed in the same manner as described with reference to FIGS. 2 and 3 in the first embodiment.

  The air duct 110 of FIG. 4 can perform the heating operation of the secondary transfer roller 11 as in the first embodiment. For example, a uniform heating operation can be performed on the entire axial direction of the secondary transfer roller 11. In the second embodiment, a separate heating operation can be performed for each of the regions 1, 2, and 3 of the secondary transfer roller 11. Usually, even if the secondary transfer roller 11 is uniformly heated, the region 2 that is the central portion is warmed first. This is because the heat in the regions 1 and 3 which are both ends of the secondary transfer roller 11 escapes to the outside. As a result, temperature non-uniformity occurs in the axial direction of the secondary transfer roller 11. Specifically, the temperature of the regions 1 and 3 is lower than the temperature of the region 2. Therefore, it is preferable to perform a heating operation for each section in the axial direction of the secondary transfer roller 11. That is, in the secondary transfer roller 11, the center region 2 reaches the target temperature first. Then, in order to warm the secondary transfer roller 11 uniformly, the fixing lamp 252 and the blower fan 162 in the region 2 are powered down or turned off. The fixing lamps 251 and 253 in the areas 1 and 3 and the blower fans 161 and 163 are continuously turned on to keep the temperatures in the areas 1 and 3 until the target temperature is reached. And when the temperature of the area | regions 1 and 3 also reaches target temperature, this heating operation will be complete | finished.

  In addition to the comparison with the target temperature described above, control by mutual comparison for each region can be performed. For example, it is assumed that the temperature of the regions 1 and 3 is lower than the temperature of the region 2 as described above. In that case, the fixing lamp 252 and the blower fan 162 in the area 2 are powered down or turned off. The fixing lamps 251 and 253 in the areas 1 and 3 and the blower fans 161 and 163 continue to be turned on. As a result, when the temperature of the regions 1 and 3 and the temperature of the region 2 become uniform, the whole is again heated uniformly. When the temperatures of the regions 1, 2, and 3 become uniform and the temperature reaches the target temperature, the heating operation ends. For such control, a certain threshold value may be provided for the temperature difference between the regions. That is, when the maximum difference between the detected areas is equal to or greater than the threshold value, the heating operation in the high temperature area is stopped or weakened. If not, warm the whole thing evenly.

  In addition to the above, there are the following examples of separate heating operations for each region in the second embodiment. By continuously printing on small size paper instead of the normal size, the temperature of the region 2 at the center of the secondary transfer roller 11 may be lower than the regions 1 and 3 at the end. This can also be determined as a heating operation start event. This is because the printing paper selectively removes the heat of the region 2 which is the central portion by passing only the central portion of the secondary transfer roller 11. However, the axial uniformity of the secondary transfer roller 11 can be recovered by separately performing the heating operation in the axial direction of the secondary transfer roller 11 as described above. In the above example, it is assumed that the temperature of the region 2 that is the central portion is lower than the target temperature. In that case, the fixing lamp 252 and the blower fan 162 in the area 2 that is the central portion are powered up or turned on. In this way, the temperature of the region 2 detected as a low temperature is quickly warmed up to the target temperature or higher.

  Alternatively, similarly to the above, control by mutual comparison can be performed for each region. In the above example, it is assumed that the temperature of the region 2 is detected to be lower than the temperatures of the regions 1 and 3. In that case, the fixing lamp 252 and the blower fan 162 in the area 2 that is the central portion are powered up or turned on. If the temperature of the region 2 reaches the temperature of the regions 1 and 3 and the regions 1, 2, and 3 reach the target temperature, the heating operation of the regions 1, 2, and 3 ends.

  In FIG. 4, when the heating operation is finished, the air duct 110 and the fixing lamps 251, 252 and 253 return to the normal state shown in FIG. 2 of the first embodiment.

  As described in detail above, in the image forming apparatus 1 according to the present embodiment, when the temperature of the secondary transfer roller 11 is considered to be low, the arrangement of each part is changed as shown in FIG. 3 to heat the fixing roller pair. However, it is assumed that air is blown by the air duct 100. Thereby, the secondary transfer roller 11 can be raised to the target temperature at an early stage. Thus, the secondary transfer roller 11 is heated so as not to cause the problem of secondary transfer failure. Further, the problem of transfer failure of the secondary transfer unit can be further improved by dividing the area and heating the secondary transfer roller 11 separately for each area as in the air duct 110 of the second embodiment. it can. Thereby, the image forming apparatus 1 with high productivity is realized without reducing the line speed.

  In addition, this Embodiment is only a mere illustration and does not limit this invention at all. Accordingly, the present invention can naturally be improved and modified in various ways without departing from the gist thereof. For example, the present invention can be applied not only to a color copier but also to a monochrome copier, and further to a multifunction machine. Further, for example, the present invention can be applied to an image forming apparatus of a type that directly transfers from a photosensitive member to a printing paper without using an intermediate transfer belt. In this case, the photosensitive member corresponds to a toner image carrier, and the exposure device and the developing device correspond to a toner image forming unit. Further, the expansion / contraction function of the air duct 100 is not absolutely necessary. For example, depending on the overall arrangement of each part of the image forming apparatus, only the fixing device 17 and the secondary transfer roller 11 are changed to the arrangement shown in FIG. 3 with respect to the normal arrangement (FIG. 2). The destination of the air current blown from the mouth 170 may be the secondary transfer roller 11. In such a case, the air duct 100 may not have an expansion / contraction function.

7 Intermediate transfer belt 11 Secondary transfer roller 17 Fixing device 28 Roller 100 Air duct 160 Air blow fan 170 Air outlet 200 Fixing lamp 250 Fixing lamp 300 Heating roller 301 Fixing roller 302 Pressure roller 303 Fixing belt 400 Temperature detection element D Air blowing path

Claims (4)

A toner image carrier for carrying a toner image;
A toner image forming unit for forming a toner image on the toner image carrier;
A transfer member that transfers a toner image on the toner image carrier to a recording medium at a position other than a position formed by the toner image forming unit;
In the image forming apparatus having a pair of fixing rollers for fixing the toner image on the recording medium by heating the recording medium that has received the transfer of the toner image by the transfer member,
An air duct that causes an air flow from the pair of fixing rollers to a transfer position by the transfer member ;
A normal arrangement in which the transfer member is pressed against the toner image carrier and the pair of fixing rollers are in contact with each other, and heating in which the transfer roller is separated from the toner image carrier and the fixing roller pair is separated An operation control unit that switches between time arrangements ,
The operation controller is
In the image formation, the transfer member and the fixing roller pair are in the normal arrangement,
In the heating operation, the transfer member and the fixing roller pair are arranged in the heating state, the heating of the fixing roller pair is turned on, and an air flow is generated by the air duct.
The air duct is
It is disposed downstream of the pair of fixing rollers in the conveyance direction of the recording medium and at a position on the toner image carrier side with respect to the conveyance path of the recording medium, and
A normal state in which airflow is blown from a discharge port to the nip portion of the fixing roller pair at the time of the normal arrangement;
It takes a heated state in which the ejection port is moved in a direction closer to the conveyance path of the recording medium than the normal state,
The operation control unit includes the air duct,
In the normal state during image formation,
An image forming apparatus that is in the warming state during a warming operation . A toner image carrier for carrying a toner image;
A toner image forming unit for forming a toner image on the toner image carrier;
A transfer member that transfers a toner image on the toner image carrier to a recording medium at a position other than a position formed by the toner image forming unit;
In the image forming apparatus having a pair of fixing rollers for fixing the toner image on the recording medium by heating the recording medium that has received the transfer of the toner image by the transfer member,
An air duct that causes an air flow from the pair of fixing rollers to a transfer position by the transfer member ;
A normal arrangement in which the transfer member is pressed against the toner image carrier and the pair of fixing rollers are in contact with each other, and heating in which the transfer roller is separated from the toner image carrier and the fixing roller pair is separated An operation control unit for switching between time arrangements;
A temperature sensor that outputs a detection value indicating the temperature of the transfer member ;
The operation controller is
In the image formation, the transfer member and the fixing roller pair are in the normal arrangement,
In the heating operation, the transfer member and the fixing roller pair are arranged in the heating state, the heating of the fixing roller pair is turned on, and an air flow is generated by the air duct.
The operation control unit starts a heating operation when there is an event corresponding to a predetermined heating operation start event,
An image forming apparatus, wherein the heating operation is terminated when a detection value of the temperature sensor reaches a predetermined target value . The image forming apparatus according to claim 1 .
A temperature sensor that outputs a detection value indicating the temperature of the transfer member;
The operation control unit starts a heating operation when there is an event corresponding to a predetermined heating operation start event,
An image forming apparatus, wherein the heating operation is terminated when a detection value of the temperature sensor reaches a predetermined target value. The image forming apparatus according to claim 2 or 3,
The air duct is divided into a plurality of sections in the width direction of the recording medium, and can discharge airflow for each section.
The fixing roller pair is capable of adjusting the heating power for each section in the width direction of the recording medium,
The temperature sensors are each provided in a width direction range corresponding to a section of the air duct,
The image forming apparatus, wherein the operation control unit performs a heating operation for each section of the air duct.

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