Image forming device

Abstract

To provide an image forming apparatus equipped with a fixing device that allows a user to easily prevent paper from curling. [Solution] A fixing device 40 that fixes an image onto paper includes a fixing roller 41, a pressure roller 42 that fixes the image onto the paper P by pressing and applying pressure to the paper P between the fixing roller 41, a fixing load adjustment device 50 that changes the pressure applied by the pressure roller 42 against the fixing roller 41, a humidity meter 46 that measures the humidity around the fixing device 40, and a curl prevention setting change table that allows the fixing load of the fixing load adjustment device 50 and the fixing temperature of the fixing device 40 to be selected, and the initial setting of the curl prevention setting change table is changed depending on the detection result of the humidity meter 46 and the conditions of the paper P.

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus equipped with a fixing device. [Background technology]

[0002] In an image forming device equipped with a fixing device, when paper with a high moisture content is used, the amount of curl (bottom curl) increases as it passes through the fixing device, which can lead to poor stacking and jams due to curl during transport of the second side of double-sided printing. To address this, conventionally, a setting change table for preventing curl, which is a combination of fixing parameters, was provided, and although the initial setting remained unchanged, upon request, a service technician could select from several patterns of fixing load adjustment and accompanying fixing temperature correction based on humidity judgment.

[0003] Also, an image forming apparatus that controls the amount of curl is disclosed in, for example, Japanese Patent Laid-Open No. 2009-109911 (Patent Document 1). According to this publication, in an environment where humidity is above a certain level, when the temperature drop on the surface of the fixing roller during continuous paper feed exceeds a threshold, the amount of curl is reduced by setting the target fixing temperature high and extending the post-rotation after fixing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-109911 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional image forming apparatuses equipped with fixing devices have been configured as described above. In conventional image forming apparatuses equipped with fixing devices, the initial settings were not changed, so service personnel were required to assist users with paper conditions that tended to curl. Furthermore, the configuration of Patent Document 1 suffers from the problem that the humidity environment affects curling, and although control is performed to prevent a large drop in temperature between the target temperature and the temperature during continuous paper feed, sufficient effectiveness is not achieved.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide an image forming apparatus equipped with a fixing device that allows the user to easily prevent paper from curling. [Means for solving the problem]

[0007] The image forming apparatus according to the present disclosure has a fixing device including a fixing roller, a pressure roller that fixes an image onto a sheet by pressing the sheet between the fixing roller and the pressure roller, a fixing load adjustment device that changes the pressure applied by the pressure roller to the fixing roller, a humidity measuring device that measures the humidity around the fixing device, and a curl countermeasure setting change table that allows selection of multiple patterns for correcting the fixing load of the fixing load adjustment device and the fixing temperature of the fixing device, and changes the initial setting of the curl countermeasure setting change table depending on the detection result of the humidity measuring device and the conditions of the sheet.

[0008] Preferably, the fixing device includes an upper roller that is heated and a lower roller that contacts the upper roller, and during continuous printing, the temperature of the lower roller may drop relative to the upper roller, increasing the temperature difference between the upper and lower rollers, and the setting of the anti-curl setting change table is changed according to the temperature of the lower roller so as to prevent the temperature difference between the upper and lower rollers from increasing.

[0009] The setting of the anti-curl setting change table may be such that an idle time is provided once for a predetermined number of sheets, or the CPM of the paper may be adjusted, so as not to increase the temperature difference between the upper and lower rollers.

[0010] The curl countermeasure setting change table may be selectable by the user according to the screen display on the display screen. [Effects of the Invention]

[0011] According to the present disclosure, the initial setting is changed depending on the detection result of the humidity measuring device and the conditions of the paper, and the stronger the curl correction setting is set as the initial setting, the more likely the paper conditions are to curl.

[0012] As a result, an image forming apparatus capable of correcting curl of paper reliably can be provided.

[0013] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description of the embodiments, which proceeds with reference to the drawings. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus including a fixing device according to an embodiment of the present disclosure, as viewed from the front; [Figure 2] FIG. 2 is a front view showing a schematic configuration of the fixing device. [Figure 3] FIG. 2 is a front view of a fixing load adjusting device provided in the fixing device. [Figure 4] 10 is a diagram showing temperature changes of the upper and lower rollers when an idling time is provided once for a predetermined number of sheets in the fixing device so that the temperature difference between the upper and lower rollers does not increase beyond a certain level. [Figure 5] FIG. 10 is a diagram showing temperature changes of the upper and lower rollers when the CPM is adjusted so that the temperature difference between the upper and lower rollers does not exceed a certain level. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present disclosure will be described in detail below with reference to the drawings. Fig. 1 is a schematic cross-sectional view of an image forming apparatus 10 equipped with a fixing device according to an embodiment of the present disclosure, viewed from the front. In Fig. 1, the symbol X indicates the width direction (depth direction), the symbol Y indicates the left-right direction perpendicular to the width direction X, and the symbol Z indicates the up-down direction. This also applies to Fig. 2, which will be described later.

[0016] 1 is a color image forming apparatus that forms multicolor and monochrome images on paper P such as recording paper by electrophotography in accordance with image data read by an image reading device 11 or image data transmitted from an external device. Note that the image forming apparatus 10 may be a monochrome image forming apparatus. Alternatively, the image forming apparatus 10 may be another type of color image forming apparatus.

[0017] The image forming apparatus 10 includes a document feeder 12 and an image forming apparatus main body 13, and the image forming apparatus main body 13 is provided with an image forming section 14 and a paper transport system 15.

[0018] The image forming section 14 includes an exposure device 30 (specifically, an exposure unit of a writing optical system), a plurality of developing devices 31-31 (specifically, developing units), a plurality of photosensitive drums 32-32, a plurality of photosensitive cleaner sections 33-33, a plurality of chargers 34-34, a primary transfer belt device 35, a plurality of toner cartridge devices 36-36 (specifically, toner cartridge units), and a fixing device 40 (specifically, a fixing unit). The paper transport system 15 also includes a paper feed tray 16, a manual paper feed tray 17 on which envelopes or the like are placed, and a discharge tray 18.

[0019] An original document table 19 made of transparent glass on which an original document (not shown) is placed is provided above the image forming apparatus main body 13, and an image reading device 11 for reading an image of the original document is provided below the original document table 19. An original document feeder 12 is also provided above the original document table 19. The image of the original document read by the image reading device 11 is sent to the image forming apparatus main body 13 as image data, and an image formed in the image forming apparatus main body 13 based on the image data is recorded on paper P. A display screen 25 is provided near the original document table 19 so that the user can display a curl countermeasure setting change table, which will be described later, and the like.

[0020] Image data handled in image forming apparatus 10 corresponds to a color image using multiple colors (in this example, black (K), cyan (C), magenta (M), and yellow (Y)). Therefore, developing devices 31, photoconductor drums 32, photoconductor cleaner units 33, chargers 34, and toner cartridge devices 36 are each set in multiple units (four units each in this example, black, cyan, magenta, and yellow) to form multiple types of images (four types in this example) corresponding to each color, and these constitute multiple (four in this example) image stations.

[0021] In image forming apparatus 10, when forming an image, a printing medium such as paper P is supplied from paper feed tray 16 or manual paper feed tray 17, and paper P is conveyed to registration rollers 21 by conveyance rollers 20a-20a provided along paper conveyance path S. Next, paper P is conveyed by secondary transfer belt device 23 at a timing when paper P and a toner image on primary transfer belt 22, which is moved circumferentially in circumferential direction M in primary transfer belt device 35, are aligned, and the toner image is transferred onto paper P. Thereafter, paper P is passed between fixing roller 41 and pressure roller 42 in fixing device 40, whereby unfixed toner on paper P is melted and fixed by heat, and paper P is discharged onto discharge tray 18 via conveyance rollers 20a and discharge roller section 24. Furthermore, in the image forming apparatus 10, when an image is to be formed on the back side of the sheet P in addition to the front side, the sheet P is conveyed in the reverse direction from the discharge roller unit 24 to the reversal path Sr, and then the sheet P is turned over via the conveyance rollers 20b and guided again to the registration rollers 21, where a toner image is fixed on the back side of the sheet P in the same manner as on the front side, and the sheet is then discharged to the discharge tray 18. In this way, the image forming apparatus 10 completes a series of printing operations.

[0022] It is also possible to form a monochrome image using at least one of the four image forming stations and transfer the monochrome image to the primary transfer belt 22 of the primary transfer belt device 35. This monochrome image is also transferred from the primary transfer belt 22 to the paper P and fixed on the paper P, just like the color image.

[0023] Next, a description will be given of a fixing load adjusting device 50 applied to a fixing device 40 according to this embodiment. The fixing device 40 includes a plurality of belt rollers (a fixing roller 41 and a heating roller 44 in this example) and an endless belt (a fixing belt 43 in this example) wound around the plurality of belt rollers. The fixing belt 43 is configured to transfer heat from the heating roller 44 to the fixing roller 41.

[0024] FIG. 2 is a front view showing a schematic configuration of fixing device 40. Referring to FIG. 2, fixing device 40 has a pressure roller 42 pressed against fixing roller 41 via fixing belt 43, and the pressing portion forms nip portion N where paper P is fixed. Fixing belt 43 is heated by heat source 45 provided inside heating roller 44 and maintained at a predetermined fixing temperature based on a signal from temperature detection device 46 (specifically, a temperature sensor such as a thermistor). Temperature detection device 46 also detects humidity and functions as a humidity meter. Therefore, hereinafter, it may be referred to as humidity meter 46. Naturally, a humidity detection device may be provided separately from the temperature detection device. In FIG. 2, arrows indicate the rotational directions of pressure roller 42 and fixing belt 43, and the transport direction of paper P.

[0025] FIG. 3 is a front view of the fixing load adjustment device 50 provided in the fixing device 40. Referring to FIG. 3, the fixing load adjustment device 50 adjusts the roller pressure of the pressure roller 42 toward the fixing roller 41. The fixing load adjustment device 50 includes a first pressure lever 52 that can contact the pressure roller 42 by receiving a biasing force from a first biasing member 51, and a second pressure lever 54 that contacts the pressure roller 42 by receiving a biasing force from a second biasing member 53 that has a biasing force smaller than that of the first biasing member 51. The second biasing member 53 is bridged between the levers 52 and 54. The rotation of the eccentric cam 56 rotates the first pressure lever 52, thereby changing the biasing forces from the biasing members 51 and 53, thereby changing the roller pressure. The rotation position of the eccentric cam 56 is determined according to the thickness of the printing medium, thereby obtaining an optimal roller pressure.

[0026] [First embodiment] Next, the anti-curl setting change table for the image forming apparatus 10 equipped with the fixing device 40 of the present disclosure will be described. Table 1 shows the anti-curl setting change table for the image forming apparatus 10 equipped with the fixing device 40 of the present disclosure. Here, the fixing conditions are set when the humidity meter 46 determines that the humidity is 61% or higher. Also, here, adjustments are made only for the plain paper group (Gr) and the recycled paper group (Gr), which are prone to curling.

[0027] [Table 1] First, the anti-curl setting change table will be described. Here, six fixing adjustment settings, 0 to 5, are provided. Each setting is as follows: Setting 0 does not perform curl correction. Therefore, no positive temperature correction for the paper or pressure reduction correction by setting the pressure position of the fixing load adjustment device 50 is performed, and the setting is indicated as "0." Setting 1 is set so that, when the humidity judgment (humidity 61% or higher) is met, the fixing temperature is raised by 10 degrees and the pressure is reduced by one level for curl correction (shown as "10" or "-1" in Table 1). Setting 2 is set so that the fixing temperature is raised by 5 degrees from Setting 1 to 15 degrees to ensure fixability when the fixing temperature is insufficient in Setting 1 (shown as "15" in Table 1). Pressure reduction correction is the same as Setting 1. Setting 3 is set so that the fixing temperature is raised by 5 degrees from Setting 2 to 20 degrees (shown as "20" in Table 1) to ensure fixability when the fixing temperature is insufficient in Setting 2.

[0028] Setting 4 is a setting that reduces the pressure of the fixing load adjusting device 50 by one level (shown as "-1" in Table 1) and raises the fixing temperature by 15 degrees (shown as "15" in Table 1) for curl correction, regardless of humidity. Setting 5 is a setting that, when the fixing temperature is insufficient with setting 4, raises the fixing temperature by 5 degrees from setting 4 to 20 degrees (shown as "20" in Table 1) to ensure fixability.

[0029] Referring to Figure 3, the pressure position setting by the fixing load adjustment device 50 is adjusted by rotating an eccentric cam 56 that supports the pressure roller 42 and moves the first and second pressure levers 52, 54, which are urged in the direction of pressing the pressure roller 42 against the nip portion N, in the pressure direction (the direction of pressing the fixing roller 41) or the pressure release direction (the direction of moving away from the fixing roller 41).

[0030] The predetermined pressure position of the eccentric cam 56 at this time is set to 0, and positions -1 to -4 are set in order in the pressure release direction, which are set as pressure position settings.

[0031] Next, the initial settings of the curl countermeasure setting change table will be described. Table 2 shows the contents of the initial settings.

[0032] [Table 2] In the past, paper curl correction was not performed as a rule, and for users who encountered problems with paper curl due to using paper that is longer in the transport direction than A4, such as A3 or B4, in a high humidity environment, or using paper with weak stiffness, a service technician would change the settings to address the problem.

[0033] In contrast, according to the present disclosure, when a high-humidity environment is used and paper that is longer in the transport direction than A4, such as A3 or B4, is used, the fixing adjustment setting automatically changes to one that performs curl correction (for example, setting 2). This is shown in Table 2 by marking setting 2 with a circle when the paper length is 300 mm or more. Also, when the paper length is less than 300 mm, setting 0 is marked with a circle, indicating that curl correction control is not performed. In addition to the above, if curl occurs regardless of humidity, such as when using paper with low stiffness, a service technician may change the setting to, for example, setting 4, which performs curl correction regardless of humidity.

[0034] As described above, in the present disclosure, the initial setting of the curl countermeasure setting change table is changed depending on the paper conditions, and the stronger the curl correction setting, the more likely the paper conditions are to curl.

[0035] Next, another form of the curl countermeasure setting change table will be described. Tables 3 to 5 are tables showing another form of the curl countermeasure setting change table.

[0036] Here, the curl adjustment setting can be set in four stages: "none," "weak," "medium," and "strong," as shown in Table 3, and temperature correction and pressure drop correction are performed for each stage for paper that is prone to curl, as in Table 1. The humidity threshold for curl correction can be set in three stages, A to C, as shown in Table 4, and the paper setting can be set in three stages, A to H, as shown in Table 5. An example of the initial settings is shown in Table 6.

[0037] [Table 3] [Table 4] [Table 5] A case where the initial settings shown in Table 6 are made under the above conditions will be explained.

[0038] [Table 6] Next, individual adjustments when the initial settings are as shown in Table 6 will be explained.

[0039] Here, individual adjustments can be made from the initial settings as shown in Tables 7 and 8. In other words, based on the initial settings, the fixing temperature and fixing pressure can be adjusted, and anti-curl control can be finely adjusted in correspondence with the type of paper. Furthermore, the individual adjustment items can be used to make further adjustments according to the characteristics of the paper.

[0040] [Table 7] As a result of the adjustment, the temperature cannot be set lower than the pre-correction temperature, or it is rounded to the pre-correction temperature.

[0041] [Table 8] As a result of the adjustment, it is not possible to set a pressure force that is not set, or the pressure force is rounded to the nearest value within the setting range.

[0042] For example, if the initial settings are as shown in Table 6, the curl adjustment setting is "weak," the humidity setting is "B," and the paper setting is "L," so the temperature correction for plain paper Gr is 10°C according to Table 3. However, if an individual adjustment of -5°C, the second from the left, is made in Table 7, then 10°C - 5°C = 5°C, and the humidity is 61% or higher, and the curl correction paper length threshold is 300mm or higher.

[0043] Next, a method for changing the settings when problems due to curling of paper occur will be described. There are the following methods for changing the settings when problems due to curling occur.

[0044] (1) As in the past, service personnel will respond on-site.

[0045] (2) A service technician remotely changes the fixing settings.

[0046] (3) The curl countermeasure settings are displayed on a user selection screen (display screen 25, see FIG. 1) to allow the user to change the settings.

[0047] (4) The setting can be changed so that the service technician can select whether or not to perform (3).

[0048] (5) Depending on the number of problems caused by curl, the settings can be changed to automatically enable (3).

[0049] (6) When (3) becomes possible, a message informing the user of this is displayed on the display screen 25 (see FIG. 1).

[0050] [Second embodiment] Next, we will explain how to deal with the problem of increased curl caused by an increase in the temperature difference between the upper and lower rollers due to a drop in the temperature of the lower roller during continuous printing. The problem of increased curl occurs when the temperature difference between the upper and lower rollers increases due to a drop in the temperature of the lower roller during continuous printing. In this embodiment, to address this problem, the curl adjustment settings are changed in response to the drop in temperature of the lower roller. To achieve this, a curl adjustment setting change table similar to Table 1, as shown in Table 9, is used.

[0051] Here, the lower roller refers to the pressure roller 42 shown in FIGS. 2 and 3, and the upper roller refers to the fixing roller 41 shown in FIGS.

[0052] [Table 9] As shown in Table 9, the temperature difference between the upper and lower rollers is classified into four ranges from less than 80°C to 120°C or more, and the larger the temperature difference, the stronger the curl correction setting, similar to the settings shown in Table 1.

[0053] Next, we will explain another form of curl adjustment setting according to the temperature difference between the upper and lower rollers. In this form of curl adjustment setting, corrections such as those shown in Table 10 are added to the current setting according to the temperature difference between the upper and lower rollers, regardless of whether curl adjustment setting is enabled or disabled.

[0054] [Table 10] If the additional correction results in a pressure force that is not set, the value is rounded to the nearest value within the set range.

[0055] Next, we will explain the specific details of countermeasures to the problem of increased paper curl due to an increase in the temperature difference between the upper and lower rollers caused by a drop in the temperature of the lower roller during continuous printing. Figure 4 shows the temperature changes of the upper and lower rollers when an idle time is set for each predetermined number of sheets in the fixing device 40 to prevent the temperature difference between the upper and lower rollers from increasing beyond a certain level. In the figure, the vertical axis represents temperature and the horizontal axis represents time, showing the temperature 27a of the upper roller and the temperature 28a of the lower roller. As shown in Figure 4, the temperature of the lower roller decreases each time a sheet of paper is passed through the upper and lower rollers. To prevent this decrease from continuing, an idle time T is set in which no paper is passed through the fixing device 40 after each predetermined number M of sheets have been passed through the fixing device 40.

[0056] That is, referring to FIG. 4, here, regardless of whether or not curl adjustment is set, the rollers are configured to perform idling (operation in which paper P is not passed) for T time every predetermined number M of sheets according to the temperature difference between the upper and lower rollers.

[0057] Here, idling starts when the upper and lower rollers reach the target upper and lower roller temperature difference (indicated as "target upper and lower roller temperature difference" in the figure) between the upper roller temperature 27a and the lowest temperature of the lower roller temperature 28a shown by the dotted line in Figure 4. The reason for setting a specific idling time and a specific number of sheets is that this is a curl countermeasure aimed at not lowering job efficiency too much, rather than accurately maintaining the upper and lower roller temperature difference.

[0058] If job efficiency is not an issue, control may be performed so that the rollers are idling when the temperature difference between the upper and lower rollers falls below a target temperature difference.

[0059] Next, we will explain another measure to prevent the temperature difference between the upper and lower rollers from increasing beyond a certain level, which is a problem of increased curl caused by a drop in the temperature of the lower roller during continuous printing. Figure 5 shows the temperature changes of the upper and lower rollers when adjusting the CPM (Copy Per Minute) to prevent the temperature difference between the upper and lower rollers from increasing beyond a certain level. In the figure, the upper temperature is indicated by 27b and the lower temperature by 28b. The vertical and horizontal axes and the target temperature difference between the upper and lower rollers are the same as in Figure 4.

[0060] Referring to FIG. 5, regardless of whether curl adjustment is set or not, the CPM is changed according to the temperature difference between the upper and lower rollers to maintain the target temperature difference between the upper and lower rollers (indicated as "target temperature difference between the upper and lower rollers" in the figure).

[0061] Here, we reduce the CPM from 100% to 40%, which is shown in Table 11.

[0062] [Table 11] Next, the selection of such a curl countermeasure setting change table will be described. The curl countermeasure setting change table is selected from Tables 12 to 14. Specifically, the user can make the selection according to the screen display on display screen 25 (see FIG. 1) provided on image forming apparatus 10.

[0063] Here, the curl adjustment setting "medium", the curl correction humidity threshold "61% or more", and the curl correction paper length threshold "L" are set as the initial settings, and other settings can be selected by the user.

[0064] [Table 12] [Table 13] [Table 14] Next, the individual adjustment items in this case will be explained. Tables 15 and 16 are tables showing the fine adjustment items for temperature adjustment and pressure position setting depending on the paper, and are similar to Tables 7 and 8 explained above.

[0065] [Table 15] As a result of the adjustment, the temperature cannot be set lower than the pre-correction temperature, or it is rounded to the pre-correction temperature.

[0066] [Table 16] As a result of the adjustment, it is not possible to set a pressure force that is not set, or the pressure force is rounded to the nearest value within the setting range.

[0067] As shown in Tables 15 and 16, temperature correction is possible in five stages from -10°C to 10°C, and pressure drop correction is possible in five stages from -2 to 2.

[0068] As described above, in this embodiment, by changing the curl adjustment setting according to the lower roller temperature, it is possible to address the problem of increased curl due to an increase in the temperature difference between the upper and lower rollers caused by a drop in the lower roller temperature during continuous printing.

[0069] The present disclosure can be implemented in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments are merely examples and should not be interpreted as being limited. All modifications and variations within the scope of the claims of the present disclosure are within the scope of the present disclosure. [Industrial Applicability]

[0070] According to the present disclosure, an image forming apparatus capable of reliably correcting curl of paper can be provided, and therefore is useful as an image forming apparatus. [Explanation of symbols]

[0071] 10 Image forming device 11 Image reading device 12 Document feeder 13 Image forming device main body 14 Image forming unit 15 Paper transport system 16 Paper tray 17 Manual feed tray 18 Output tray 19 Document stand 20a, 20b Conveyor rollers 21 Registration roller 22 Primary transfer belt 23 Secondary transfer belt 24 Discharge roller section 25 Display screen 30 Exposure equipment 31 Developing device 32 Photosensitive drum 33 Photoconductor cleaner 34 Charger 35 Primary transfer belt device 36 Toner cartridge device 40 Fixing device 41 Fuser roller (upper roller) 42 Pressure roller (lower roller) 43 Fixing belt 44 Heating roller 45 Heat source 46 Temperature detection device (humidity measuring device) 50 Fixing load adjustment device 51 first biasing member 52 First pressure lever 53 Second biasing member 54 Second pressure lever 56 Eccentric cam

Claims

1. An image forming apparatus having a fixing device that fixes an image on a sheet, The fixing device includes a fixing roller and a pressure roller that fixes an image on the paper by pressing the paper between the fixing roller and the pressure roller. a fixing load adjusting device for adjusting the pressure of the pressure roller against the fixing roller; a humidity measuring device for measuring the humidity around the fixing device; a curl countermeasure setting change table that allows selection of a plurality of patterns for correcting the fixing load of the fixing load adjusting device and the fixing temperature of the fixing device, The image forming apparatus changes the initial setting of the curl countermeasure setting change table depending on the detection result of the humidity measuring device and the conditions of the paper.

2. the fixing device includes an upper roller that is heated and a lower roller that contacts the upper roller; During continuous printing, the temperature of the lower roller may decrease relative to the temperature of the upper roller, increasing the temperature difference between the upper and lower rollers.

2. The image forming apparatus according to claim 1, wherein the setting of the anti-curl setting change table is changed in accordance with the temperature of the lower roller so as to prevent an increase in the temperature difference between the upper and lower rollers.

3. 3. The image forming apparatus according to claim 2, wherein the setting of the curl countermeasure setting change table is changed by providing an idle rotation time once for each predetermined number of sheets of paper so as not to increase the temperature difference between the upper and lower rollers.

4. 3. The image forming apparatus according to claim 2, wherein the setting change in the curl countermeasure setting change table adjusts the CPM of the paper so as not to increase the temperature difference between the upper and lower rollers.

5. 2. The image forming apparatus according to claim 1, wherein the curl countermeasure setting change table is selectable by a user according to a screen display on a display screen.

Images