JP7131182B2 - Image forming apparatus and image forming method - Google Patents

Description

The present invention relates to an image forming apparatus and an image forming method.

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus, printing position misalignment between the front and back sides may occur when both sides of paper are fed. Such print position misalignment between the front and back surfaces is caused by contraction due to evaporation of moisture from the paper due to fixing heat and a difference in contraction due to a difference in paper cooling effect of the cooling unit heat pipe that suppresses evaporation of moisture after fixing. Therefore, it is already known that a user performs writing registration position adjustment and printing position adjustment of a print document.

Further, in Patent Document 1, for the purpose of improving fixability and saving energy, preheating is performed by absorbing the heat of the transfer paper after fixing and dissipating the absorbed heat to the transfer paper before fixing upstream from the fixing unit. However, a technique for realizing energy saving as well as improving fixability is disclosed.

However, with the conventional adjustment method, the temperature of the heat pipe in the cooling section after fixing increases with the passage of printing time, causing changes in the amount of cooling and shrinkage of the paper compared to the initial stage of printing. Also, there is a problem that the front and back positions are misaligned between print jobs.

More specifically, when the heat pipe temperature is low, the amount of paper shrinkage can be reduced by suppressing the evaporation of moisture. quantity becomes large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and it is an object of the present invention to reduce front-back misalignment in printing even when the temperature of a cooling unit rises due to continued printing.

In order to solve the above-described problems and achieve the object, the present invention provides an image forming unit that forms a toner image and transfers it onto a transfer material, and heats the toner image that has been transferred onto the transfer material by the image forming unit. a fixing unit that fixes the image by means of the fixing unit; a cooling unit that cools the transfer material after the fixing by the fixing unit; a fixing control unit that executes control to increase the amount of heat applied to the transfer material in the unit.

ADVANTAGE OF THE INVENTION According to this invention, even if the temperature of a cooling part rises by continuation of printing, it is effective in the front-back position misalignment of printing being able to be reduced.

FIG. 1 is a block diagram of a schematic configuration of an image forming apparatus according to an embodiment. FIG. 2 is a block diagram showing the main system configuration of the image forming apparatus. FIG. 3 is a diagram showing a schematic configuration of a fixing section and a cooling section. FIG. 4 is a diagram illustrating an example of temperature transition during normal fixing temperature control. FIG. 5 is a flowchart schematically showing the flow of setting processing for the temperature control mode of the fixing section. FIG. 6 is a flow chart schematically showing the flow of fixing temperature control. FIG. 7 is a diagram illustrating an example of temperature transition during fixing temperature control based on the temperature of the cooling unit. FIG. 8 is a diagram illustrating an example of temperature transition during fixing temperature control based on the temperature of the cooling section. FIG. 9 is a flow chart schematically showing the flow of fixing linear velocity control. FIG. 10 is a diagram illustrating an example of temperature transition during fixing line speed control based on the temperature of the cooling unit. FIG. 11 is a flow chart schematically showing the flow of fixing nip width control. FIG. 12 is a diagram illustrating an example of temperature transition during fixing nip width control based on the temperature of the cooling section.

Exemplary embodiments of an image forming apparatus and an image forming method will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic configuration of an image forming apparatus 101 according to an embodiment. In FIG. 1, an image forming apparatus 101 is generally called a multifunction peripheral/printer/product (MFP) having at least two functions out of a copy function, a printer function, a scanner function, and a facsimile function. As an example, the image forming apparatus 101 is an image forming apparatus capable of full-color printing using four colors of C (cyan), M (magenta), Y (yellow), and K (black). For simplification of explanation, FIG. 1 does not show a discharge reversing path or the like used for double-sided printing.

As shown in FIG. 1, the image forming apparatus 101 includes an operation panel 104, paper feed trays 105 and 106, an intermediate transfer belt 107, a fixing section 108, a cooling section 109, a paper discharge tray 117, and a secondary transfer roller 120. I have. The image forming apparatus 101 also includes laser scanning units 110Y, 110M, 110C, and 110K for four colors of C (cyan), M (magenta), Y (yellow), and K (black), chargers 111Y, 111M, and 111C. , 111K. The image forming apparatus 101 also includes photosensitive drums 112Y, 112M, 112C and 112K, developing devices 113Y, 113M, 113C and 113K, and primary transfer rollers 114Y, 114M, 114C and 114K.

The paper feed trays 105 and 106 each contain paper 116 as a transfer material. The image forming apparatus 101 prints a printed matter according to a print execution instruction input via the operation panel 104 . Specifically, the image forming apparatus 101 acquires image data from a reading device (hereinafter referred to as a scanner) or from the outside. The captured image data is embodied as a latent image through image processing by the image processing board.

The latent images are created using photoreceptor drums 112Y, 112M, 112C, and 112K provided in the image forming units. First, a high voltage is applied to the chargers 111Y, 111M, 111C and 111K from the charging high voltage power supply 150 to uniformly charge the photosensitive drums 112Y, 112M, 112C and 112K. As an example, a high voltage of -700 kV is uniformly applied to the photosensitive drums 112Y, 112M, 112C, and 112K, although the current value is very small. This forms a base for drawing the latent image.

Next, the charged photosensitive drums 112Y, 112M, 112C and 112K are irradiated with laser beams corresponding to the image data from the laser scanning units 110Y, 110M, 110C and 110K. As a result, the voltage of the portions of the uniformly charged photosensitive drums 112Y, 112M, 112C, and 112K irradiated with the laser beam drops to, for example, about -400 kV. A latent image is drawn (exposure) at the potential difference level due to such laser light irradiation.

Next, when toner is applied to the photosensitive drums 112Y, 112M, 112C, and 112K on which the latent images are drawn, the toner remains in the portions where the voltage is lowered due to the irradiation of the laser light, and the toner remains in the portions not irradiated with the laser light. does not remain (development). Such a process is performed for each of the colors Y, M, C and K. As a result, toner images of Y, M, C, and K colors corresponding to the image data are formed on the photosensitive drums 112Y, 112M, 112C, and 112K, respectively.

Next, each toner image drawn on the photosensitive drums 112Y, 112M, 112C, and 112K and formed by applying toner of each color is transferred to the primary transfer belt 107, respectively. Here, the toner images on the photosensitive drums 112Y, 112M, 112C, and 112K are not transferred onto the intermediate transfer belt 107 by simply superimposing them on the intermediate transfer belt 107 . To transfer each toner image onto the intermediate transfer belt 107, the photosensitive drums 112Y, 112M, 112C and 112K and the intermediate transfer belt 107 are driven to rotate at a constant speed. Also, a voltage is applied to the primary transfer rollers 114Y, 114M, 114C, and 114K from a primary transfer high-voltage power supply 151 provided inside the primary transfer unit.

As a result, negative charges are generated on the primary transfer rollers 114Y, 114M, 114C and 114K, and positively charged toner is attracted onto the intermediate transfer belt 107 from the photosensitive drums 112Y, 112M, 112C and 112K. The toner images of respective colors formed on the photosensitive drums 112Y, 112M, 112C, and 112K are attracted to the intermediate transfer belt 107 and transferred. Note that such a transfer process is performed for all colors Y, M, C, and K in the case of color printing, but is performed only for the color K in the case of monochrome printing.

Next, the intermediate transfer belt 107 is rotated by the intermediate transfer motor, and the toner images of each color transferred onto the intermediate transfer belt 107 are conveyed to the contact position between the intermediate transfer belt 107 and the secondary transfer roller 120 . The paper 116 stacked on the paper feed tray 105 is conveyed to the position of the secondary transfer roller 120 so as to coincide with the timing at which the toner image is conveyed to the position of the secondary transfer roller 120 . Then, the toner image of each color is transferred to the paper 116 at the position of the secondary transfer roller 120 . Specifically, a high voltage is applied to the secondary transfer roller 120 from the secondary transfer high-voltage power supply 152 to generate a negative charge on the secondary transfer roller 120 . As a result, the toner image on the intermediate transfer belt 107 is attracted to the paper 116 side and transferred to the paper 116 . The paper 116 onto which the toner image has been transferred is conveyed by the conveying belt 115 and discharged to the paper discharge tray 117 via the fixing section 108 and the cooling section 109 .

As described above, in the image forming apparatus 101, the paper 116 bearing the unfixed toner image that has just been transferred is passed through the fixing unit 108, and the unfixed toner image on the paper 116 is fixed. is cooled in the cooling section 109 and then discharged.

Next, a main system configuration of the image forming apparatus 101 will be described.

FIG. 2 is a block diagram showing the main system configuration of the image forming apparatus 101. As shown in FIG. As shown in FIG. 2, the image forming apparatus 101 includes an image forming section 200 that forms a toner image on a photosensitive drum and transfers the toner image to a sheet 116 by the process steps according to the above-described electrophotographic process, and a fixing section that controls a fixing section . It includes a control unit 201, a main control unit 203 that controls the entire image forming apparatus 101, and an image processing unit 204 that executes various types of image processing.

Image forming unit 200 includes paper feed trays 105 and 106, intermediate transfer belt 107, secondary transfer roller 120, and the like.

The fixing control unit 201 includes a fixing temperature control unit 19, a pressure roller speed control unit 20 as a fixing linear speed control unit, a pressure nip control unit 21 as a fixing nip width control unit, and a cooling unit temperature control unit 22. there is

The fixing control unit 201 may be implemented by an electronic circuit such as an IC, or may be implemented by software.

When realized by software, the fixing control unit 201 has a computer configuration including a control device such as a CPU and a storage device such as a ROM (Read Only Memory) or a RAM for storing programs.

The program executed by the fixing control unit 201 of the present embodiment is a file in an installable format or an executable format, and can be stored in a computer such as a CD-ROM, a flexible disk (FD), a CD-R, a DVD (Digital Versatile Disk), or the like. provided on a recording medium readable by

Further, the program executed by the fixing control unit 201 of this embodiment may be stored in a computer connected to a network such as the Internet, and may be provided by being downloaded via the network. Also, the program executed by the fixing control unit 201 of this embodiment may be provided or distributed via a network such as the Internet.

Further, the program executed by the fixing control unit 201 of the present embodiment may be configured so as to be pre-installed in a ROM or the like and provided.

Next, the fixing section 108 and the cooling section 109 will be described.

FIG. 3 is a diagram showing a schematic configuration of the fixing section 108 and the cooling section 109. As shown in FIG. As shown in FIG. 3, the fixing unit 108 includes a heating roller 3, a fixing roller 4, a fixing belt 5, a pressure roller 6, a heating heater 7, a heating heater 8, a heating roller temperature sensor 9, a pressure roller temperature sensor 10, A fixing inlet upper guide plate 11, a fixing inlet lower guide plate 12, a fixing outlet upper guide plate 13, and a fixing outlet lower guide plate 14 are provided.

The cooling unit 109 includes a cooling roller 15 , a cooling belt 16 , a cooling roller temperature sensor 17 , and a cooling inlet upper guide plate 18 . The cooling roller 15 is composed of a heat pipe.

A paper 116 bearing a toner image is guided by an upper fixing inlet guide plate 11 and a lower fixing inlet guide plate 12, and conveyed to a fixing nip formed by a fixing roller 4 and a pressure roller 6 via a fixing belt 5. . The fixing belt 5 has a fixing roller 4 and a heating roller 3 inside, and is heated by a heater 7 inside the heating roller 3 . The temperature of the heating roller is controlled by turning on/off the heater 7 through the fixing temperature control section 19 based on the temperature detected by the heating roller temperature sensor 9 .

Formation of the fixing nip is controlled by a pressure nip control section 21 that controls pressure release/pressurization of the pressure roller 6 . The driving of the fixing belt 5 and the pressure roller 6 is controlled by a pressure roller speed control section 20, and the fixing belt 5 rotates together. The temperature of the pressure roller 6 is detected by a pressure roller temperature sensor 10 and controlled by a pressure roller controller (not shown).

The fixed paper 116 is guided by the fixing exit upper guide plate 13 and the fixing exit lower guide plate 14 and conveyed to the cooling section 109 . The cooling unit 109 is configured to absorb the heat of the paper 116 and exhaust the heat to the outside of the apparatus. The cooling unit 109 detects the temperature of the cooling roller 15 with the cooling roller temperature sensor 17, and controls the fixing temperature with the cooling unit temperature control unit 22 based on the detected temperature.

Next, a function of performing temperature control of the fixing unit 108 according to the temperature of the cooling unit 109, which is a characteristic function among the functions realized by the fixing control unit 201 of the image forming apparatus 101 of the present embodiment, will be described. do.

FIG. 4 is a diagram illustrating an example of temperature transition during normal fixing temperature control. FIG. 4 shows an example of temperature transition of the fixing section (heating roller) when there is a start-up request such as power ON. As shown in FIG. 4, when a print request is received, the main controller controls the temperature of the heating roller to the control temperature _T0 at the start of paper feeding, and starts paper feeding. After that, the main control unit controls the control temperature to the control temperature T1 at the time of paper feeding, and when printing is completed, the _main control unit shifts to the standby mode.

However, as shown in FIG. 4, the temperature of the heat pipe in the cooling section after fixing increases with the passage of printing time, causing changes in the amount of cooling and shrinkage of the paper compared to the initial stage of printing. However, there is a problem that the front and back positions are misaligned between print jobs.

Therefore, the fixing control unit 201 of the image forming apparatus 101 controls the temperature of the fixing unit 108 according to the temperature of the cooling unit 109 . In this embodiment, three types of control modes are prepared for temperature control of the fixing section 108: fixing temperature control, fixing linear speed control, and fixing nip width control. A control mode setting method in print settings will be described below.

FIG. 5 is a flowchart schematically showing the flow of setting processing for the temperature control mode of fixing section 108 . As shown in FIG. 5, first, the fixing control unit 201 determines whether the paper 116, which is the transfer material, is thick paper in the print settings (step S1). When the thickness of the paper 116 is equal to or greater than a predetermined value, the fixing control unit 201 sets the paper 116 having a thickness of 100 gsm or more, for example, as thick paper. However, it is not limited to this, and thick paper may be set from a paper thickness greater than that.

If the paper 116 is thick paper (Yes in step S1), the fixing control unit 201 proceeds to a normal fixing control flow (step S2). In the case of thick paper, the shrinkage of the paper 116 during printing on the first side is small. It is possible to do paper.

On the other hand, when the paper 116 is not thick paper (No in step S1) and productivity is prioritized over productivity and durability (Yes in step S3), the fixing control unit 201 controls the pressure nip control unit 21 (step S4).

If the paper 116 is not thick paper (No in step S1) and productivity is not prioritized, that is, durability is prioritized (No in step S3), the fixing control unit 201 sets the print volume to 5 sheets. It is determined whether or not (step S5).

If the print request is for a small number of sheets, 5 or less (Yes in step S5), the fixing control unit 201 proceeds to the fixing linear speed control flow by the pressure roller speed control unit 20 (step S6). This is because it takes time to raise the fixing temperature to the set temperature, so in the case of a job with a small number of sheets, even if the line speed is reduced, the total paper feeding time can be shortened.

If the number of sheets is more than 5 (No in step S5), the fixing control section 201 proceeds to the fixing temperature control flow by the fixing temperature control section 19 (step S7).

In this embodiment, the fixing control section 201 has all of the fixing temperature control section 19, the pressure roller speed control section 20, and the pressure nip control section 21, but has at least two control sections. At least two control units may be selectively switched.

First, the fixing temperature control flow (step S7) by the fixing control unit 201 will be described.

FIG. 6 is a flow chart schematically showing the flow of fixing temperature control. As shown in FIG. 6, when a print request is received (step S11), the fixing control unit 201 determines whether the temperature _{THP of the cooling unit 109 is higher than a threshold value TFHP (} step S12). If the temperature T _HP of the cooling unit 109 is higher than the threshold T _FHP (Yes in step S12), the fixing control unit 201 starts feeding paper under normal temperature control (steps S13 and S14). As described with reference to FIG. 4, the fixing control unit 201 performs normal sheet feeding start temperature control _T0 at the start of sheet feeding, and then performs sheet _feeding temperature control T1.

On the other hand, when the temperature _{THP of the cooling unit 109 is equal to or lower than the threshold value TFHP (} No in step S12), the fixing control unit 201 performs temperature control to the control temperature _TFO at the start of sheet passage countermeasure for front/rear misalignment (step S15). ), and printing is started (step S16).

After printing is started, the fixing control unit 201 determines again whether the temperature _{THP of the cooling unit 109 is higher than the threshold value TFHP (} step S17). When the temperature _{THP of the cooling unit 109 is higher than the threshold value TFHP (} Yes in step S17), the fixing control unit 201 performs normal temperature control T1 during sheet _feeding (step S18).

If the temperature _{THP of the cooling unit 109 is equal to or lower than the threshold T FHP (} No in step S17), the fixing control unit 201 causes the fixing temperature control unit 19 to set the fixing temperature to the control temperature T _F1 during paper feeding for countermeasures against misalignment of the front and back sides. The sheet feeding is continued under control (step S19).

Further, if there is a request to continue printing (Yes in step S20), the fixing control unit 201 returns to step S17 and repeats determination of fixing control based on the temperature of the cooling unit 109 again. Then, the fixing control unit 201 terminates the process when there is no request to continue printing (No in step S20).

Here, FIG. 7 is a diagram illustrating an example of temperature transition during fixing temperature control based on the temperature of the cooling unit 109 . FIG. 7 shows an example of temperature transition of the fixing section 108 (heating roller 3) when there is a start-up request such as power ON. As shown in FIG. 7, when a print request is received, the cooling unit 109 (heat pipe) temperature T _HP is equal to or lower than the _threshold T _FHP . control to

After that, the sheet is started to pass, and the temperature _THP of the cooling unit ₁₀₉ (heat pipe) is equal to or lower than the threshold value T _FHP . When the temperature THP becomes _{equal to or higher than the threshold value TFHP ,} the fixing control unit 201 performs control at the control temperature during normal sheet feeding. That is, in the example shown in FIG. 7, the temperature _{THP of the cooling unit 109 (heat pipe) becomes equal to or lower than the threshold T FHP before} the temperature drops to the control temperature T _F1 at the time of front-back misalignment countermeasure paper passage. .

Here, FIG. 8 is a diagram illustrating an example of temperature transition during fixing temperature control based on the temperature of the cooling unit 109 . FIG. 8 also shows an example of the temperature transition of the fixing section 108 (heating roller 3) when there is a start-up request such as power ON. As shown in FIG. 7, when a print request is received, the cooling unit 109 (heat pipe) temperature T _HP is equal to or lower than the _threshold T _FHP . control to After that, the paper is started to pass, but the temperature _THP of the cooling unit 109 (heat pipe) is still lower than the threshold _{T FHP} . . When the sheet feeding is continued and the temperature _{THP of the cooling unit 109 (heat pipe) becomes higher than the threshold value TFHP ,} the fixing control unit 201 performs control at the normal sheet feeding time control temperature. An example of each temperature is given here. The following temperature is an example, and is characterized by T _F0 >T ₀ and T _F1 >T ₁ .
_TF0 : 180°C _TF1 : 160°C _T0 : 165°C T1: ₁₅₀ °C

Next, the fixing line speed control flow (step S6) by the fixing control unit 201 will be described.

FIG. 9 is a flow chart schematically showing the flow of fixing linear velocity control. As shown in FIG. 9, when a print request is received (step S21), the fixing control unit 201 determines whether the temperature _{THP of the cooling unit 109 is higher than a threshold value TFHP (} step S22). When the temperature T _HP of the cooling unit 109 is higher than the threshold T _FHP (Yes in step S22), the fixing control unit 201 starts feeding paper with normal fixing line speed control (D ₁ ) (step S23).

On the other hand, if the temperature _{THP of the cooling unit 109 is equal to or lower than the threshold value TFHP (} No in step S22), the fixing control unit 201 controls the linear velocity D _F1 to prevent front/back misalignment (step S24), and starts printing. (Step S25).

After printing is started, the fixing control unit 201 determines again whether the temperature _{THP of the cooling unit 109 is higher than the threshold value TFHP (} step S26). When the temperature _{THP of the cooling unit 109 is higher than the threshold TFHP ( Yes} in step S26), the fixing control unit 201 performs the line speed control D1 during normal sheet feeding (step S27).

When the temperature _{THP of the cooling unit 109 is equal to or lower than the threshold TFHP (} No in step S26), the fixing control unit 201 causes the pressure roller speed control unit 20 to set the fixing linear speed to the linear speed D _F1 for countering misalignment between the front and back sides. The sheet feeding is continued under control (step S28).

Further, if there is a request to continue printing (Yes in step S29), the fixing control unit 201 returns to step S26 and repeats determination of the linear fixing speed control based on the temperature of the cooling unit 109 again. Then, the fixing control unit 201 terminates the process when there is no request to continue printing (No in step S29).

Here, FIG. 10 is a diagram for explaining an example of temperature transition during fixing line speed control based on the temperature of the cooling unit 109 . FIG. 10 shows an example of linear velocity transition of the fixing section 108 (heating roller 3) when there is a start-up request such as power ON. As shown in FIG. 10, when a print request is received, the temperature _{THP of the cooling unit 109 (heat pipe) is equal to or lower than the threshold TFHP after} startup and preparation for printing. Control to speed _VF1 .

After that, the sheet is started to pass, but since the temperature _{THP of the cooling unit 109 (heat pipe) is still equal to or lower than the threshold value TFHP ,} the fixing control unit 201 maintains the linear velocity _VF1 for countering front/rear misalignment. Further, when the cooling unit 109 (heat pipe) temperature _{THP becomes higher than the threshold value TFHP as} the paper continues to pass, the fixing control unit 201 performs normal linear speed control at the _linear speed V1.

Here, the linear velocity at the start-up/preparation for printing is an example, and the linear velocity may be different from the normal linear velocity during paper feeding. Here, an example of each linear velocity is given. The following linear velocity is an example, and is characterized by V _F1 <V ₁ .
V _F1 : 380 mm/s V ₁ : 420 mm/s

Next, the fixing nip width control flow (step S4) by the fixing control section 201 will be described.

FIG. 11 is a flow chart schematically showing the flow of fixing nip width control. As shown in FIG. 11, when a print request is received (step S31), the fixing control unit 201 determines whether the temperature _{THP of the cooling unit 109 is higher than a threshold value TFHP (} step S32). If the temperature T _HP of the cooling unit 109 is higher than the threshold T _FHP (Yes in step S32), the fixing control unit 201 starts feeding paper with normal fixing nip width control (H ₀ ) (step S33).

On the other hand, if the temperature T _HP of the cooling unit 109 is equal to or lower than the threshold T _FHP (No in step S32), the fixing control unit 201 controls the nip width _HF1 to prevent front/back misalignment (step S34), and starts printing. (Step S35).

After printing is started, the fixing control unit 201 determines again whether the temperature _{THP of the cooling unit 109 is higher than the threshold value TFHP (} step S36). If the temperature _{THP of the cooling unit 109 is higher than the threshold TFHP ( Yes} in step S36), the fixing control unit 201 performs the normal nip width control H1 (step S37).

When the temperature T _HP of the cooling unit 109 is equal to or lower than the threshold T _FHP (No in step S36), the fixing control unit 201 causes the pressure nip control unit 21 to control the fixing nip width to the nip width H _F1 for countering misalignment between the front and back sides. Then, the sheet feeding is continued (step S38).

Further, if there is a request to continue printing (Yes in step S39), the fixing control unit 201 returns to step S36 and repeats determination of fixing nip width control based on the temperature of the cooling unit 109 again. Then, the fixing control unit 201 terminates the process when there is no request to continue printing (No in step S39).

Here, FIG. 12 is a diagram for explaining an example of temperature transition during fixing nip width control based on the temperature of the cooling unit 109 . FIG. 12 shows an example of transition of the nip width of the fixing section 108 (heating roller 3) when there is a start-up request such as power ON. As shown in FIG. 12, when a print request is received, the temperature _{THP of the cooling unit 109 (heat pipe) is equal to or lower than the threshold TFHP after} startup and preparation for printing. Control to width H _F1 .

After that, the sheet is started to pass, but since the temperature _{THP of the cooling unit 109 (heat pipe) is still equal to or lower than the threshold value TFHP ,} the fixing control unit 201 performs control with the nip width _HF1 for counter-front/rear misalignment as it is. Further, when the cooling unit 109 (heat pipe) temperature _{THP becomes higher than the threshold value TFHP as the} paper continues to pass, the fixing control unit 201 performs normal nip width control at the nip width H1.

Here, the nip width during start-up/print preparation is an example, and the nip width may be different from the normal nip width during paper feeding. An example of each nip width is given here. The following nip width is an example, and is characterized by H _F1 >H ₁ .
_HF1 : _17.5mm H1: 16mm

As described above, according to the present embodiment, even if the temperature of the cooling unit rises due to the continuation of printing, it is possible to reduce the misalignment of the front and back sides of printing.

In the above embodiment, the image forming apparatus 101 of the present invention is applied to a multifunctional machine having at least two functions out of a copy function, a printer function, a scanner function, and a facsimile function. It can be applied to any image forming apparatus such as a machine, a printer, a facsimile machine, and the like.

19 Fixing Temperature Control Section 20 Fixing Line Speed Control Section 21 Fixing Nip Width Control Section 101 Image Forming Apparatus 108 Fixing Section 109 Cooling Section 200 Image Forming Section 201 Fixing Control Section

JP 2011-180312 A

Claims (6)

an image forming unit that forms a toner image and transfers it onto a transfer material;
a fixing unit that heats and fixes the toner image transferred onto the transfer material by the image forming unit;
a cooling unit that cools the transfer material after being fixed by the fixing unit;
a fixing control unit that increases the amount of heat given to the transfer material by the fixing unit when the thickness of the transfer material is equal to or less than a predetermined value and the temperature of the cooling unit is lower than the predetermined value;
An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein the control is fixing temperature control for increasing the temperature of the fixing section. 2. The image forming apparatus according to claim 1, wherein the control is linear fixing speed control for slowing the linear speed of a roller of the fixing section. 2. The image forming apparatus according to claim 1, wherein the control is fixing nip width control for increasing the nip width of the fixing nip formed in the fixing section. The fixing control unit
a fixing temperature control unit that increases the temperature of the fixing unit;
a fixing linear speed control unit that slows down the linear speed of a roller of the fixing unit;
a fixing nip width control unit that increases the nip width of the fixing nip formed in the fixing unit;
At least two or more of
When the thickness of the transfer material is equal to or less than a predetermined value and the temperature of the cooling unit is lower than the predetermined value, either one can be selectively executed.
2. The image forming apparatus according to claim 1, wherein: An image forming section that forms a toner image and transfers it onto a transfer material, a fixing section that heats and fixes the toner image transferred onto the transfer material by the image forming section, and the transfer material after being fixed by the fixing section. An image forming method in an image forming apparatus comprising a cooling unit for cooling,
a fixing control step of increasing the amount of heat applied to the transfer material by the fixing unit when the thickness of the transfer material is equal to or less than a predetermined value and the temperature of the cooling unit is lower than a predetermined value;
An image forming method characterized by:

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