JP2018063387A - Fixing device, image forming apparatus, and method for controlling image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a reduction in productivity in a mixed job in which the types of recording media are switched.SOLUTION: In a predetermined printing mode where printing of a second job using a second recording medium is executed while a first job using a first recording medium is continuously printed, a fixing device determines the number of printed second jobs (S103), when the number of prints is equal to or less than a predetermined number N1, changes the linear velocity of the fixing device between the first job and second job (S104), and when the number of prints exceeds the predetermined number, changes the preset temperature of the fixing device between the first job and second job (S105).SELECTED DRAWING: Figure 5

Description

  The present invention relates to a fixing device, an image forming apparatus, and a control method for the image forming apparatus.

  Various image forming apparatuses using an electrophotographic system have been devised as image forming apparatuses such as copying machines, facsimiles, and printers, and are well-known techniques. In the image forming process, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier based on image information, and the electrostatic latent image on the photosensitive drum can be developed with toner as a developer. By visualizing and developing the developed image onto a recording medium (also called paper) by a transfer device to carry the image, and fixing the unfixed toner image on the recording medium by a fixing device using pressure, heat, or the like It is established.

  In recent years, image forming apparatuses have become more colorized, faster, and higher in image quality. For example, in the field of on-demand publications, it is relatively easy to handle small copies. The tendency to create publications that have been created by printing methods with color copiers and printers has become prominent.

  Various types of fixing devices for image forming apparatuses have been proposed. For example, a pressure roller, a fixing roller disposed opposite to the pressure roller, and a tension roller between the fixing roller and the heating roller. An endless fixing belt, and the heat of the heating roller is applied to the recording medium via the fixing belt at a nip formed by the pressure roller being pressed against the fixing roller via the fixing belt. Thus, there is known a belt fixing system in which an unfixed toner image is pressed and fixed on a recording medium.

  In such a fixing device, there is a difference in the amount of heat required for the recording medium between a thick recording medium having a large heat capacity and a thin recording medium having a small heat capacity. For this reason, it is known that the fixing device keeps the fixing property constant by changing the temperature (set temperature) required for fixing according to the recording medium by controlling the amount of heat.

  Also, depending on the recording medium, a method that keeps the fixing property constant by changing the amount of pressurization and controlling the nip width, or the passage time of the nip part by changing the conveyance speed (linear speed) of the recording medium There are known methods for controlling the above.

  For example, in Patent Document 1, when a print job including a plurality of pages of image data is input, the paper type used in the print job is extracted, and the extracted paper type is one in the fixing control. It is determined whether or not it is possible to cope with the set values (temperature value and pressure value). If it is possible to deal with one set value, a common set value is determined. Discloses a printing apparatus that determines a set value and executes print processing according to the determined set value.

  Patent Document 2 discloses an image forming apparatus that slows the conveyance speed when the number of printed sheets of a thick sheet exceeds a predetermined number in a print job in which the type of the recording medium is switched halfway.

  However, when the set temperature is changed according to the recording medium, it takes time to change the temperature to the set temperature every time the recording medium changes, leading to a reduction in productivity. Similarly, when the conveyance speed is decreased depending on the type of the recording medium, the productivity is similarly reduced. Further, the method of changing the nip width may cause an image failure such as a decrease in glossiness.

  In the above-described prior art, there remains room for studying in suppressing a decrease in productivity in a print job (called a mixed job) in which the type of recording medium is switched halfway.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of suppressing a decrease in productivity in a mixed job in which types of recording media are switched.

  In order to achieve such an object, the fixing device according to the present invention is configured to execute printing of the second job using the second recording medium while the first job using the first recording medium is continuously printed. In the print mode, the determination unit for determining the number of prints of the second job, and the linear speed of the fixing device is changed between the first job and the second job when the number of prints is a predetermined number or less. And a set temperature control unit that changes the set temperature of the fixing device between the first job and the second job when the number of printed sheets exceeds the predetermined number.

  According to the present invention, it is possible to suppress a decrease in productivity in a mixed job in which the types of recording media are switched.

1 is a schematic configuration diagram showing an embodiment of an image forming apparatus according to the present invention. 1 is a schematic configuration diagram showing an embodiment of a fixing device according to the present invention. It is explanatory drawing (1) of productivity in the case of printing a 2nd job between 1st jobs. It is explanatory drawing (2) of productivity in the case of printing a 2nd job between 1st jobs. 6 is a flowchart illustrating an example of control when a mixed job is passed. It is an example of a setting screen displayed on the operation panel.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

(Image forming device)
An image forming apparatus according to an embodiment of the present invention will be described with reference to FIG. Examples of the image forming apparatus include an embodiment that forms an image using toner, such as a printer, a copier, a fax machine, and the like, and includes a fixing device that fixes a toner image (unfixed image) formed on a recording medium. It is.

  FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 according to the present embodiment is a tandem type intermediate transfer type, and includes a sheet feed table 200 having a sheet feed tray 44 at a lower portion.

  Further, inside the image forming apparatus 100, a tandem type intermediate transfer type tandem type image forming unit 11 in which a plurality of image forming units 18Y, 18M, 18C, and 18K are arranged in parallel is provided. Subscripts Y, M, C, and K attached to these symbols indicate yellow, magenta, cyan, and black colors, respectively.

  The image forming apparatus 100 is provided with an endless belt-like intermediate transfer member (hereinafter referred to as an intermediate transfer belt) 10 near the center. The intermediate transfer belt 10 is supported by being wound around a plurality of rollers 14, 15, 15 ′, 16, etc., and can be rotated and conveyed clockwise in FIG. 1.

  In the configuration example of FIG. 1, a cleaning device 17 for the intermediate transfer belt is provided on the downstream side in the rotation direction of the intermediate transfer belt 10 of the secondary transfer counter roller 16 which is one of such support rollers. The cleaning device 17 removes residual toner remaining on the intermediate transfer belt 10 after image transfer.

  The upper part of the intermediate transfer belt 10 that is stretched between the support roller 14 and the support roller 15 has four colors of yellow (Y), magenta (M), cyan (C), and black (K) along the conveyance direction. Image forming means 18Y, 18M, 18C, 18K are arranged. The symbol is abbreviated as 18 (Y, M, C, K) below.

  In this way, the four image forming means 18 (Y, M, C, K) are arranged side by side to constitute the tandem image forming unit 11 as described above. Each image forming means 18 (Y, M, C, K) of the tandem type image forming unit 11 is a photosensitive drum 40 (image bearing member for carrying toner images of yellow, magenta, cyan, and black). Y, M, C, K).

  Two exposure devices 12 are provided above the tandem type image forming unit 11. Each exposure device 12 is provided corresponding to two image forming means (18Y and 18M, 18C and 18K). Each exposure device 12 includes, for example, a light source device such as a semiconductor laser, a semiconductor laser array, or a multi-beam light source, a coupling optical system, a common optical deflector such as a polygon mirror, and two scanning imaging optical systems. Is an optical scanning exposure apparatus. Each exposure device 12 exposes each photosensitive drum 40 (Y, M, C, K) according to the image information of each color of yellow, magenta, cyan, and black to form an electrostatic latent image.

  Further, a charging device that uniformly charges each photosensitive drum prior to exposure is provided around the photosensitive drum 40 (Y, M, C, K) of each image forming unit 18 (Y, M, C, K). And a developing device that develops the electrostatic latent image formed by exposure with toner of each color, and a photoconductor cleaning device that removes transfer residual toner on the photoconductor drum.

  Further, primary transfer rollers 62 (Y, M, C, K) are provided at primary transfer positions for transferring toner images from the respective photosensitive drums 40 (Y, M, C, K) to the intermediate transfer belt 10. Yes. The primary transfer rollers 62 (Y, M, C, K) are provided so as to face the respective photosensitive drums 40 (Y, M, C, K) with the intermediate transfer belt 10 interposed therebetween, and serve as primary transfer means. It becomes a component.

  Among the plurality of support rollers that support the intermediate transfer belt 10, the support roller 14 is a drive roller that rotationally drives the intermediate transfer belt 10, and is connected to a motor via a drive transmission mechanism such as a gear, a pulley, or a belt. Yes. Further, when a black single color image is formed on the intermediate transfer belt 10, the support rollers 15 and 15 ′ other than the support roller 14 are moved by the moving mechanism, and the photosensitive drum 40 (Y, M, C) is moved. ) Can be separated from the intermediate transfer belt 10. In addition, the backup roller 63 is also provided as a supporting roller.

  A secondary transfer device 13 is provided on the opposite side of the intermediate transfer belt 10 from the tandem image forming unit 11. The secondary transfer device 13 transfers the image on the intermediate transfer belt 10 to the sheet-like recording medium P by pressing the secondary transfer roller 16 ′ against the secondary transfer counter roller 16 and applying a transfer electric field. .

  Further, a fixing device 20 that fixes a transfer image on the recording medium P is provided on the downstream side in the transport direction of the secondary transfer device 13. The recording medium P on which the image has been transferred by the secondary transfer device 13 is conveyed to the fixing device 20 by a conveyance belt 38 supported by two rollers 37. Of course, the conveyance belt 38 may be a fixed guide member, a conveyance roller, a conveyance roller, or the like.

  A sheet reversing device 39 for reversing and transporting the recording medium P to record images on both sides of the recording medium P is provided below the tandem image forming unit 11, the secondary transfer device 13, and the fixing device 20.

  The recording medium P is transported as follows. First, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated to feed the recording medium P from one of the paper feed trays 44 provided in multiple stages in the paper bank 43. The fed recording medium P is separated one by one by the separation roller 45, introduced into the paper feed path 46, transported by the transport roller pair 47, and guided to the paper feed path 48 in the image forming apparatus 100. After that, it is abutted against the positioning roller (registration roller) pair 49 and stopped.

  When the manual feed tray 51 is used, the paper feed roller 50 is rotated to feed out the recording medium P on the manual feed tray 51, and the fed recording medium P is separated one by one by the separation roller 52. After that, it is introduced into the manual paper feed path 53 and similarly abutted against the positioning roller pair 49 and stopped.

  Thereafter, the positioning roller pair 49 is rotated in synchronization with the full-color toner image formation on the intermediate transfer belt 10, and the recording medium P is placed at the secondary transfer position between the intermediate transfer belt 10 and the secondary transfer roller 16 ′. It is sent. Then, the full-color toner image on the intermediate transfer belt 10 is collectively transferred onto the recording medium P.

  The recording medium P on which the toner image has been transferred is conveyed by the conveying belt 38 and sent to the fixing device 20. After the toner image transferred by heat and pressure is fixed by the fixing device 20, the recording medium P is fixed. The paper is discharged onto the paper discharge tray 57 by the discharge roller 56 and stacked.

  In the case of double-sided copying, the recording medium P having an image fixed on one side is introduced into the sheet reversing device 39 and reversed, and then guided again to the secondary transfer position, and the image is also transferred to the back surface. Then, the paper is discharged onto a paper discharge tray 57 by a discharge roller 56.

(Fixing device)
FIG. 2 shows an example of the fixing device 20, and is a schematic sectional view in the axial direction of the fixing roller 22.

  The fixing device 20 includes a heating roller 21, a fixing roller 22, a fixing belt 24 stretched between the heating roller 21, the fixing roller 22, and the tension roller 27, and the fixing roller 22 by pressing the fixing roller 22. A pressure roller 23 for forming a nip portion is provided. The heating roller 21 has a heater 25 as a heat source, and the pressure roller 23 has a heater 26 as a heat source.

  The fixing device 20 passes a recording medium P carrying an unfixed toner image T (transfer image) through a nip portion between the fixing belt 24 and the pressure roller 23 formed by pressure contact between the fixing roller 22 and the pressure roller 23. Paper is used for heat fixing. The heating roller 21, the fixing roller 22, and the pressure roller 23 are pivotally supported so as to be rotatable in the longitudinal direction of the casing of the fixing device 20, and the driving means and the like of each roller are fixedly held on the casing.

  The recording medium P that has passed through the nip portion is separated at its leading end by a separation plate 28 disposed on the fixing roller 22 side or a separation plate 29 disposed on the pressure roller 23 side, and is discharged to the next process. The separation plates 28 and 29 as separation members disposed on the fixing roller 22 side and the pressure roller 23 side are not limited to plate-like members, and separation claws may be used.

  The heating roller 21 is a thin cylindrical body made of, for example, a metal material, and a heater 25 as a heat source is fixed inside the cylindrical body. As the heater 25, for example, a halogen heater or a carbon heater can be used. Further, both end portions of the heater 25 are fixed to the casing of the fixing device 20. The heater 25 may be induction heating means (IH heating means) for heating the heating roller 21 from the outside.

  The output of the heater 25 is controlled by a power supply unit (AC power supply) of the apparatus main body, and the heating roller 21 is heated by the radiant heat from the heater 25. Further, heat is applied to the unfixed toner image T on the recording medium P from the surface of the fixing belt 24 heated by the heating roller 21. The output of the heater 25 is controlled by the control unit 31 based on the detection result of the belt surface temperature by the temperature sensor 30 such as a thermopile provided at a position facing the surface of the fixing belt 24. The installation position and the number of installation of the temperature sensor are not limited to this, and a temperature sensor for detecting the temperature of the pressure roller 23, a temperature sensor for detecting the temperature of the fixing roller 22, and the like are provided, and based on this, a heater is provided. 25 and 26 may be controlled.

  The fixing belt 24 is wound around the fixing roller 22 and the heating roller 21, and is in close contact with the heating roller 21 and the fixing roller 22. The fixing nip portion is configured by pressing the pressure roller 23 against the fixing belt 24 configured as described above at a position corresponding to the fixing roller 22.

  The fixing belt 24 is an endless belt having a two-layer structure in which an elastic layer such as a silicon rubber layer (300 to 500 μm) is formed on a base material such as nickel, stainless steel, or polyimide.

  The fixing belt 24 may be an endless belt having a multilayer structure in which an elastic layer such as silicone rubber and a release layer are sequentially laminated on a base layer made of PI (polyimide) resin and having a layer thickness of 90 μm. The elastic layer has a layer thickness of about 200 μm, for example, and is formed of an elastic material such as silicone rubber, fluorine rubber, and foamable silicone rubber. The release layer has, for example, a layer thickness of about 20 μm and is formed of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin), polyimide, polyetherimide, PES (polyether sulfide), or the like. By providing the release layer on the surface layer of the fixing belt 24, the releasability (peelability) for the toner (toner image) is ensured.

  The fixing roller 22 does not have a heat source, and is formed by covering a highly rigid core material (core metal) such as metal (iron or aluminum) with a thick elastic layer such as silicone rubber.

  Similar to the fixing roller 22, the pressure roller 23 is a roller member in which an elastic layer such as fluorine rubber, silicone rubber, and foamable silicone rubber is formed on a core metal such as SUS304. A heater 26 as a heat source is fixed inside the cylindrical body. In addition, it is good also as a structure which does not have the heater 26. FIG.

  The fixing roller 22 and the pressure roller 23 are rubber rollers arranged to face each other. When the pressure roller 23 is pressed toward the center of the fixing roller 22 via the fixing belt 24, the pressure roller 23. And a fixing belt 24 form a nip portion. Further, the nip width can be controlled by controlling the pressing force (pressing force) of the pressure roller 23 toward the fixing roller 22.

  The control unit 31 is a controller that executes various controls of the fixing device 20. For example, the control unit 31 is connected to a CPU as a calculation unit, a RAM or ROM as a storage unit, an input / output interface, and the like via a bus. The control unit 31 may be the control unit of the fixing device 20, or the control unit of the image forming apparatus 100 may also serve as the control unit 31.

  For example, the control unit 31 controls a driving unit that drives the fixing roller 22 to rotate the fixing roller 22 in the clockwise direction. As the fixing roller 22 rotates, the pressure roller 23 and the fixing belt 24 that are in pressure contact with the fixing roller 22 rotate at the same speed.

  The storage unit of the control unit 31 stores or temporarily stores parameters such as a predetermined number N1 and a predetermined temperature T1, which will be described below, setting information, and the like as necessary. The control unit 31 further includes a determination unit 32 that performs determination of the number of printed sheets of the second job and determination of whether or not the set temperature of the second job is higher than the set temperature of the first job by a predetermined temperature or more. The linear speed controller 33 that controls the linear speed of the fixing device 20 (and the image forming apparatus 100) by controlling the means and the like, and the heaters 25 and 26 are controlled by heating to control the fixing device 20 to a desired set temperature. And a set temperature control unit 34. Further, the control unit 31 controls each unit of the image forming apparatus 100 and the fixing device 20 such as input reception from the operation panel 35 described later, display control, and the like.

(Fixing device control)
Hereinafter, control of the fixing device 20 will be described. First, while a job (referred to as a first job) using a predetermined recording medium (first recording medium) is continuously printed, a job (second job) using a different recording medium (second recording medium) is performed. A print mode to be printed will be described. Hereinafter, a print job including two or more jobs using different types of recording media is referred to as a mixed job. Such mixed jobs are often used, for example, during bookbinding printing.

  Here, the first recording medium is thin paper, for example, and the set temperature of the fixing device 20 in the first job is set low. In addition, the second recording medium is a recording medium having a larger heat capacity than at least the first recording medium, such as cardboard or special media, and the set temperature of the fixing device 20 in the second job is at least the first job. Higher than.

  FIG. 3 is an explanatory diagram of productivity when printing a second job (printing five thick sheets) during a continuous first job (printing 100 sheets of thin paper). Here, a description will be given on the assumption that a job of 5 sheets of thick paper (second job) is printed between two jobs of 100 sheets of thin paper (two first jobs), but a job of 200 sheets of thin paper (one first job). The same applies to the case of printing a five-sheet job (second job) in the middle of the job.

  FIG. 3A is an explanatory diagram of productivity in the case where control is performed to keep the fixing property constant by changing the set temperature according to the recording medium. As shown in FIG. 3A, when the set temperature of the fixing device 20 is changed between the first job and the second job, the downtime required for temperature tracking increases and the productivity decreases. End up.

  On the other hand, in FIG. 3B, fixing is performed by changing the linear speed of the fixing device 20 to be slower in passing the paper in the second job while keeping the setting temperature in the first job without changing the set temperature. It is explanatory drawing of productivity in the case of performing control which keeps property constant. When changing the linear velocity without changing the set temperature between the first job and the second job, downtime for temperature tracking is not required. At this time, the passing time of the cardboard increases and a downtime is required for changing the linear speed. However, since the number of cardboard printed is small, the influence is small and the downtime is short. The decrease in productivity can be suppressed as compared with the case of (A).

  That is, as shown in FIG. 3, in a job with a relatively small number of second jobs (thick paper), the first job (thin paper) to the second job (thick paper) and the second job (thick paper) to the first job Considering the downtime when the set temperature is switched to (thin paper), it can be said that the productivity is not lowered by changing the linear speed at the time of printing the second job (thick paper) without changing the set temperature.

  Next, an example in which a second job with a relatively large number of prints is printed during the first job will be described. FIG. 4 is an explanatory diagram of productivity when a second job (printing 80 sheets of thick paper) is printed during a continuous first job (printing 100 sheets of thin paper). 3A, FIG. 4A shows a case where the set temperature is changed according to the recording medium, and FIG. 4B shows a case where the set temperature is not changed, and FIG. It is explanatory drawing of productivity in the case of changing the line speed of late.

  Unlike the case shown in FIG. 3, when the number of prints of the second job (thick paper) increases as in the example shown in FIG. 4, when the linear velocity is reduced as shown in FIG. The effect of productivity reduction when passing a job (thick paper) is increased, and the productivity is lower than when the set temperature is changed according to the recording medium.

  That is, as shown in FIG. 4, in a job with a relatively large number of pages in the second job (thick paper), if the linear speed is slowed down in the second job, the influence becomes large, so the linear speed is not changed. In addition, it can be said that the productivity does not decrease when the set temperature is changed.

  Therefore, in the fixing device according to the present embodiment, the second job using the second recording medium (for example, thick paper) is continuously printed while the first job using the first recording medium (for example, thin paper) is continuously printed. In a predetermined print mode (for example, bookbinding mode) in which printing is performed, a determination unit (determination unit 32, S103 in FIG. 5) that determines the number of printed sheets of the second job, and the number of printed sheets is equal to or less than the predetermined number (N1). , The linear speed control unit (linear speed control unit 33, S104 in FIG. 5) for changing the linear speed of the fixing device (fixing device 20) between the first job and the second job, and the number of printed sheets is a predetermined number. A set temperature control unit (set temperature control unit 34, S105 in FIG. 5) that changes the set temperature of the fixing device between the first job and the second job. In addition, the code | symbol in embodiment and the example of application are shown in a parenthesis.

  FIG. 5 is a flowchart illustrating an example of control by the control unit 31 when a mixed job is passed.

  First, it is determined whether it is a predetermined mode (S101). The predetermined mode here is a bookbinding mode. When the bookbinding mode is selected (S101: Yes), it is determined whether or not the set temperature corresponding to the recording medium of the second job is greater than the set temperature of the first job by T1 or more (S102).

  If the set temperature is higher than T1 (S102: Yes), it is determined whether or not the number of printed sheets of the second job is equal to or less than the predetermined number N1 (S103). When the number of printed sheets of the second job is equal to or less than the predetermined number N1 (S103: Yes), control is performed to change the linear speed slower without changing the set temperature in the second job (S104).

  On the other hand, when the bookbinding mode is not selected (S101: No), when the set temperature is not higher than T1 (S102: No), and when the number of printed sheets of the second job exceeds the predetermined number N1 (S103: No) ) Does not change the linear velocity in the second job, but executes the change control to the set temperature according to the recording medium (S105).

  A specific control example will be described with reference to Table 1. Here, N1 = 10 [sheets] and T1 = 20 [° C.].

  As shown in (a), when the set temperature for the first job is 130 ° C., the number of printed sheets is 100, the set temperature for the second job is 170 ° C., and the number of printed sheets is 1, the set temperature is the first temperature. Since the set temperature is + 40 ° C., it is larger than T1 and the number of printed sheets is N1 or less, so the linear speed in the second job is changed.

  On the other hand, as shown in (b), when the set temperature for the first job is 140 ° C., the number of printed sheets is 2, the set temperature for the second job is 170 ° C., and the number of printed sheets is 15, the set temperature is Since it is one set temperature + 30 ° C., it is larger than T1, but since the number of printed sheets exceeds N1, the linear speed in the second job is not changed.

  As shown in (c), when the set temperature in the first job is 150 ° C., the number of printed sheets is 100, the set temperature in the second job is 165 ° C., and the number of printed sheets is 2, the number of printed sheets is N1. Although the following is set, the set temperature is the first set temperature + 15 ° C., which is equal to or less than T1, and therefore the linear velocity in the second job is not changed.

  As shown in (d), when the set temperature for the first job is 150 ° C., the number of printed sheets is 100, the set temperature for the second job is 165 ° C., and the number of printed sheets is 30, the set temperature is Since the set temperature + 15 ° C. is equal to or lower than T1, and the number of printed sheets exceeds N1, the linear speed in the second job is not changed.

  According to the fixing device according to the present embodiment described above, it is possible to suppress a decrease in productivity in a mixed job in which the types of recording media are switched. In particular, it is preferable to reduce the productivity of print jobs including switching of recording media that have a large paper type and paper thickness, such as mixed jobs of relatively small number of thick paper and large number of thin paper, mixed media of special media, etc. Can be suppressed.

  Hereinafter, a further preferred embodiment of the fixing device according to this embodiment will be described. It is preferable that the predetermined print mode for executing the linear speed change control during the mixed job passing described so far can be set by the user. The set temperature set according to the recording medium is preferably a value according to the paper type paper thickness information of the recording medium set by the user. Hereinafter, a setting example by the user will be described.

  The control unit 31 displays each setting screen shown in FIG. 6 on the operation panel 35 of the image forming apparatus 100, and the operation content by the user on the operation panel 35 is input to the control unit 31. FIG. 6A shows a job list management screen. The user can set the paper type paper thickness information of each job by changing the settings of the jobs 71 to 73.

  FIG. 6B is a print mode selection screen (detail mode screen) that is displayed when the “detail mode” button 74 on the job list management screen of FIG. 6A is selected. On this print mode selection screen, for example, when the “bookbinding mode” button 75 is selected, an ON / OFF setting screen as shown in FIG. 6C is displayed, and the user can set “bookbinding mode” on / off. It has become.

  In the above example, the linear speed is changed under a predetermined condition for the second job. However, the changed linear speed is adjusted by a value corresponding to the difference between the set temperatures of the first job and the second job. It is preferable to do. Further, it is preferable that the threshold value (predetermined number N1) for determining the number of printed sheets of the second job is also adjusted with a value corresponding to the difference between the set temperatures of the first and second jobs. Table 2 shows a list of the linear speed adjustment value [%] and the predetermined number N1 according to the difference between the set temperatures of the first job and the second job.

  As shown in Table 2, the larger the set temperature difference, the more suitable control is achieved by increasing the linear velocity adjustment value and decreasing the value of the predetermined number N1.

  A specific control example will be described with reference to Table 3. Here, T1 = 10 [° C.].

  As shown in (a), when the set temperature in the first job is 135 ° C., the number of printed sheets is 100, the set temperature in the second job is 170 ° C., and the number of printed sheets is 5, the set temperature is the first temperature. Since the set temperature is + 35 ° C., the linear velocity is −60%.

  As shown in (b), when the set temperature in the first job is 135 ° C., the number of printed sheets is 100, the set temperature in the second job is 170 ° C., and the number of printed sheets is 8, the set temperature is One set temperature + 35 ° C. In this case, since the predetermined number N1 = 6, the linear speed is not changed.

  As shown in (c), when the set temperature for the first job is 150 ° C., the number of printed sheets is 100, the set temperature for the second job is 170 ° C., and the number of printed sheets is 8, the set temperature is Since the set temperature is + 20 ° C., the linear velocity is −30%.

  As shown in (d), when the set temperature for the first job is 150 ° C., the number of printed sheets is 100, the set temperature for the second job is 155 ° C., and the number of printed sheets is 2, the set temperature is Since the temperature is one set temperature + 5 ° C., the linear velocity is not changed.

  Further, it is more preferable that the linear velocity adjustment value is set to a different value between color printing and monochrome printing. Table 4 shows an example of setting the linear velocity adjustment values for color printing and monochrome printing.

  The linear speed adjustment values shown in Table 4 are applied when changing the linear speed of the second job, and further adjust the determined linear speed adjustment values in the monochrome mode. This is because, in the monochrome mode, the toner adhesion amount is small compared to the color mode, so that fixing can be performed with a low amount of heat. The linear velocity adjustment shown in Table 4 may be performed together with the adjustment according to the set temperature shown in Table 3.

  In the linear speed adjustment control, if possible, only the linear speed of the fixing device 20 may be changed instead of the overall linear speed of the image forming apparatus 100. For example, in the image forming apparatus 100 having a relatively low linear velocity, when the linear velocity adjustment value is small, only the linear velocity in the fixing device 20 may be changed instead of the linear velocity of the entire apparatus.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Intermediate transfer belt 11 Tandem type image forming part 12 Exposure device 13 Secondary transfer device 14 Support roller 15 Support roller 15 'Support roller 16 Secondary transfer counter roller 16' Secondary transfer roller 17 Cleaning device 18 Image forming means 20 Fixing device 21 Heating roller 22 Fixing roller 23 Pressure roller 24 Fixing belt 25 Heater 26 Heater 27 Tension roller 28 Separating plate 29 Separating plate 30 Temperature sensor 31 Control unit 32 Determination unit 33 Linear speed control unit 34 Set temperature control unit 35 Operation panel 37 Roller 38 Conveying belt 39 Sheet reversing device 40 Photosensitive drum 42 Paper feeding roller 43 Paper bank 44 Paper feeding tray 45 Separating roller 46 Paper feeding path 47 Carrying roller pair 48 Paper feeding path 49 Positioning roller pair 50 Paper feeding roller 51 Manual tray 52 Separation Roller 53 Manual feed path 56 Discharge Roller 57 Paper discharge tray 62 Primary transfer roller 63 Backup roller 100 Image forming apparatus 200 Paper feed table T Unfixed toner image P Recording medium

JP 2010-190914 A JP2013-231803A

Claims (10)

In a predetermined print mode in which printing of the second job using the second recording medium is executed while the first job using the first recording medium is continuously printed.
A determination unit for determining the number of printed sheets of the second job;
A linear speed control unit that changes a linear speed of the fixing device between the first job and the second job when the number of printed sheets is a predetermined number or less;
A fixing device comprising: a set temperature control unit that changes a set temperature of the fixing device between the first job and the second job when the number of printed sheets exceeds the predetermined number. The determination unit determines whether a set temperature of the second job is higher than a set temperature of the first job by a predetermined temperature,
The linear velocity control unit adjusts the linear velocity when the set temperature of the second job is higher than the preset temperature of the first job by a predetermined temperature or more, and when the number of printed sheets is equal to or less than the predetermined number of sheets. The fixing device according to claim 1, wherein the fixing device is changed. The second recording medium has a larger heat capacity than the first recording medium,
The fixing device according to claim 1, wherein the linear velocity control unit makes a linear velocity at the time of passing the second job slower than that at the time of passing the first job.   The fixing device according to claim 2, wherein the linear velocity control unit changes the linear velocity to a different value according to a difference between a set temperature of the first job and a set temperature of the second job. .   The fixing device according to claim 2, wherein the determination unit changes the predetermined number of sheets according to a difference between a set temperature of the first job and a set temperature of the second job.   The fixing device according to claim 1, wherein the linear velocity control unit changes the linear velocity to a value different between color printing and monochrome printing.   The fixing device according to claim 1, wherein the set temperature is determined based on paper type paper thickness information of a recording medium used for each job set by a user.   The fixing device according to claim 1, wherein the predetermined print mode can be set by a user.   An image forming apparatus comprising the fixing device according to claim 1. In a predetermined print mode in which printing of the second job using the second recording medium is executed while the first job using the first recording medium is continuously printed.
A determination process for determining the number of printed sheets of the second job;
A linear speed control process for changing a linear speed of the fixing device between the first job and the second job when the number of printed sheets is a predetermined number or less;
A control method for an image forming apparatus, comprising: performing a set temperature control process for changing a set temperature of the fixing device between the first job and the second job when the number of printed sheets exceeds the predetermined number of sheets. .

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