JP6840983B2 - Fixing device, image forming device, and control method of image forming device - Google Patents

Description

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

As an image forming apparatus for copiers, facsimiles, printers, etc., various image forming apparatus using an electrophotographic method have been devised and are known techniques. In the image forming process, an electrostatic latent image is formed on the surface of the photosensitive drum which is an image carrier based on the image information, and the electrostatic latent image on the photosensitive drum is developed with toner or the like which is a developing agent. By the process of visualizing, transferring the developed image to a recording medium (also called paper) by a transfer device, supporting the image, and fixing the unfixed toner image on the recording medium by a fixing device using pressure, heat, etc. It is established.

In recent years, colorization, high speed, and high image quality of image forming apparatus have been progressing. For example, in the field of on-demand publications, it is relatively easy and it is possible to handle a small number of copies. There is a marked tendency to create publications using the printing method up to now with color copiers and printers.

Various types of fixing devices have been proposed for the image forming apparatus. For example, a pressure roller, a fixing roller arranged to face the pressure roller, and a tensioning device between the fixing roller and the heating roller. An endless fixing belt is provided, and the heat of the heating roller is applied to the recording medium via the fixing belt at the nip portion formed by pressing the pressurizing roller against the fixing roller via the fixing belt. Therefore, a belt fixing method is known in which an unfixed toner image is pressed against a recording medium and fixed.

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.

In addition, a method that keeps the fixability constant by changing the pressurization amount and controlling the nip width according to the recording medium, or changing the transport speed (linear speed) of the recording medium to change the passing time of the nip portion. There is a known method of controlling.

For example, in Patent Document 1, when a print job containing image data of a plurality of pages is input, the type of paper used in this print job is extracted, and the extracted paper type is one in the fixing control. Determine whether or not the set values (temperature value, pressure value) can be used, and if one set value can be used, determine a common set value. If not, use each paper type. Discloses a printing apparatus that determines a set value and executes a printing process according to the determined set value.

Further, Patent Document 2 discloses an image forming apparatus that slows down the transport speed when the number of printed sheets of thick paper exceeds a predetermined number in a printing job in which the type of recording medium is switched in the middle.

However, when the set temperature is changed according to the recording medium, it takes time to change the set temperature every time the recording medium is changed, which leads to a decrease in productivity. Further, when the transport speed is slowed down depending on the type of recording medium, the productivity is similarly lowered. In addition, the method of changing the nip width may lead to the occurrence of image defects such as a decrease in glossiness.

In the above-mentioned conventional technique, there is room for consideration in suppressing a decrease in productivity in a print job (referred to as a mixed job) in which the types of recording media are switched in the middle.

Therefore, an object of the present invention is to provide a fixing device capable of suppressing a decrease in productivity in a mixed job in which the types of recording media are switched.

In order to achieve such an object, in the fixing device according to the present invention, while the first job using the first recording medium is continuously printed, the printing of the second job using the second recording medium is executed. In the print mode of, the determination unit for determining the number of prints of the second job , and when the number of prints is a predetermined number or less, the linear speed of the fixing device is changed between the first job and the second job. It includes a linear speed control unit 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 of sheets.

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.

It is a schematic block diagram which shows one Embodiment of the image forming apparatus which concerns on this invention. It is a schematic block diagram which shows one Embodiment of the fixing device which concerns on this invention. It is explanatory drawing (1) of productivity in the case of printing a second job between the first jobs. It is explanatory drawing (2) of productivity at the time of printing a 2nd job during a 1st job. It is a flowchart which shows an example of the control at the time of mixed job paper passing. This is an example of the setting screen displayed on the operation panel.

Hereinafter, the configuration according to the present invention will be described in detail based on the embodiments shown in FIGS. 1 to 6.

(Image forming device)
An embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. Examples of the image forming apparatus include an embodiment in which an image is formed using toner such as a printer, a copying machine, and a fax machine, and includes a fixing device for fixing a toner image (unfixed image) formed on a recording medium. Is.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus 100 of the present embodiment. The image forming apparatus 100 of the present embodiment is a tandem type intermediate transfer type, and includes a paper feed table 200 having a paper feed tray 44 at the bottom.

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 means 18Y, 18M, 18C, 18K are arranged side by side is provided. The subscripts Y, M, C, and K attached to these codes indicate the colors of yellow, magenta, cyan, and black, respectively.

The image forming apparatus 100 is provided with an endless belt-shaped intermediate transfer body (hereinafter, intermediate transfer belt) 10 near the center. The intermediate transfer belt 10 is supported by being hung on a plurality of rollers 14, 15, 15', 16 and the like, and can be rotationally conveyed clockwise in FIG.

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 opposed 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.

On the upper part of the intermediate transfer belt 10 stretched between the support roller 14 and the support roller 15, four yellow (Y), magenta (M), cyan (C), and black (K) are applied along the transport direction. Image forming means 18Y, 18M, 18C, 18K are arranged. The reference numerals are 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 form the tandem type image forming unit 11 as described above. Each of the image forming means 18 (Y, M, C, K) of the tandem type image forming unit 11 is a photoconductor drum 40 (Y, M, C, K) as an image carrier for supporting toner images of yellow, magenta, cyan, and black, respectively. It has Y, M, C, K).

Two exposure devices 12 are provided above the tandem image forming unit 11. Each exposure device 12 is provided corresponding to two image forming means (18Y and 18M, 18C and 18K), respectively. 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 using a polygon mirror, and two scanning imaging optical systems. It is an optical scanning type exposure apparatus composed of. Each exposure device 12 exposes each photoconductor 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, around the photoconductor drum 40 (Y, M, C, K) of each image forming means 18 (Y, M, C, K), a charging device that uniformly charges each photoconductor drum prior to exposure. A developing device that develops an 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 are provided.

Further, a primary transfer roller 62 (Y, M, C, K) is provided at the primary transfer position for transferring the toner image from each photoconductor drum 40 (Y, M, C, K) to the intermediate transfer belt 10. There is. The primary transfer roller 62 (Y, M, C, K) is provided so as to face each photoconductor drum 40 (Y, M, C, K) with an intermediate transfer belt 10 in between, and is used as a primary transfer means. It becomes a component.

Of 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. There is. When a black monochromatic image is formed on the intermediate transfer belt 10, the support rollers 15 and 15'other than the support rollers 14 are moved by the moving mechanism to move the photoconductor drum 40 (Y, M, C). ) 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 side of the intermediate transfer belt 10 opposite to the tandem image forming unit 11. The secondary transfer device 13 transfers the image on the intermediate transfer belt 10 to the sheet-shaped recording medium P by pressing the secondary transfer roller 16'on the secondary transfer opposed roller 16 and applying a transfer electric field. ..

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

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

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

When the manual feed tray 51 is used, the paper feed roller 50 is rotated to feed 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. Later, it is introduced into the manual feed feed path 53, and is similarly abutted against the positioning roller pair 49 and stopped.

After that, the positioning roller pair 49 is rotated in time with the formation of the full-color toner image 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'. Be sent in. 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 is transferred is conveyed by the transport belt 38 and sent to the fixing device 20, and heat and pressure are applied by the fixing device 20 to fix the transferred toner image. It is ejected onto the output tray 57 by the ejection roller 56 and stacked.

In the case of double-sided copying, the recording medium P on which the image is fixed on one side is introduced into the sheet reversing device 39, inverted, and then guided to the secondary transfer position again, and the image is also transferred to the back side, and the fixing device 20 After being fixed with, the paper is discharged onto the paper discharge tray 57 by the discharge roller 56.

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

The fixing device 20 is between the heating roller 21, the fixing roller 22, the fixing belt 24 stretched on the heating roller 21, the fixing roller 22, and the tension roller 27, and the fixing roller 22 by pressing the fixing roller 22. It includes a pressure roller 23 and the like that form a nip portion. Further, the heating roller 21 has a heater 25 as a heat source, and the pressurizing roller 23 has a heater 26 as a heat source inside.

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. It is made of paper and heat-fixed. The heating roller 21, the fixing roller 22, and the pressurizing roller 23 are rotatably supported in the longitudinal direction of the housing of the fixing device 20, and the driving means and the like of each roller are fixedly held in the housing.

The tip of the recording medium P that has passed the nip portion is separated by the separation plate 28 arranged on the fixing roller 22 side or the separation plate 29 arranged on the pressure roller 23 side, and is discharged to the next step. The separation plates 28 and 29 as the separation members arranged on the fixing roller 22 side and the pressure roller 23 side, respectively, are not limited to the plate-shaped members, and separation claws may be used.

The heating roller 21 is, for example, a thin-walled cylinder made of a metal material, and a heater 25 as a heat source is fixedly installed inside the cylinder. As the heater 25, for example, a halogen heater, a carbon heater, or the like can be used. Further, both ends of the heater 25 are fixed to the housing of the fixing device 20. Further, the heater 25 may be an induction heating means (IH heating means) for heating the heating roller 21 from the outside.

The output of the heater 25 is controlled by the power supply unit (AC power supply) of the main body of the apparatus, 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 control of the heater 25 is performed 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 number of temperature sensors are not limited to this, and a temperature sensor for detecting the temperature of the pressurizing roller 23, a temperature sensor for detecting the temperature of the fixing roller 22, and the like are provided, and a heater is provided based on the temperature sensor. 25, 26 may be controlled.

The fixing belt 24 is hung 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 formed by pressing the pressurizing roller 23 against the fixing belt 24 configured in this way against the portion 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.

Further, the fixing belt 24 may be, for example, an endless belt having a multi-layer structure in which an elastic layer such as silicone rubber and a release layer are sequentially laminated on a base layer having a layer thickness of 90 μm made of PI (polyimide) resin. The elastic layer has, for example, a layer thickness of about 200 μm and is formed of an elastic material such as silicone rubber, fluororubber, or foamable silicone rubber. The release layer has a layer thickness of, for example, about 20 μm, and is formed of PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin), polyimide, polyetherimide, PES (polyethersulfide), or the like. By providing the release layer on the surface layer of the fixing belt 24, the release property (peeling property) with respect to 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.

Like the fixing roller 22, the pressure roller 23 is a roller member in which an elastic layer such as fluororubber, silicone rubber, or foamable silicone rubber is formed on a core metal such as SUS304. Further, a heater 26 as a heat source is fixedly installed inside the cylindrical body. The heater 26 may not be provided.

The fixing roller 22 and the pressure roller 23 are rubber rollers arranged to face each other, and the pressure roller 23 is pressed toward the center of the fixing roller 22 via the fixing belt 24, so that the pressure roller 23 is pressed. A nip portion is formed between the fixing belt 24 and the fixing belt 24. Further, the size of the nip width can be controlled by controlling the pressing force (pressing force) of the pressurizing roller 23 on the fixing roller 22 side.

Further, the control unit 31 is a controller that executes various controls of the fixing device 20. In the control unit 31, for example, a CPU as a calculation unit, a RAM or ROM as a storage unit, an input / output interface, and the like are connected 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 device 100 may also serve as the control unit 31.

The control unit 31 controls, for example, the driving means for driving the fixing roller 22 to rotationally drive the fixing roller 22 in the clockwise direction. Due to the rotation of the fixing roller 22, the pressure roller 23 and the fixing belt 24 that are in pressure contact with the fixing roller 22 rotate at the same speed.

Further, in the storage unit of the control unit 31, parameters such as a predetermined number of sheets N1 and a predetermined temperature T1 described below, setting information, and the like are stored or temporarily stored as needed. Further, the control unit 31 is driven by a determination unit 32 that executes determination of the number of prints 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 control unit 33 that controls the means and the like to control the linear velocity of the fixing device 20 (and the image forming apparatus 100) and the heaters 25 and 26 are heated and controlled to control the fixing device 20 to a desired set temperature. It includes a set temperature control unit 34. Further, the control unit 31 controls each unit of the image forming device 100 and the fixing device 20 such as input reception from the operation panel 35 and display control described later.

(Control of fixing device)
Hereinafter, the control of the fixing device 20 will be described. First, while a job (called 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. The print mode to be printed will be described. Hereinafter, a print job including two or more jobs using recording media of different types is referred to as a mixed job. It should be noted that such a mixed job is often used, for example, during bookbinding printing.

Here, the first recording medium is, for example, thin paper, and the set temperature of the fixing device 20 in the first job is set low. Further, the second recording medium is a recording medium having at least a heat capacity larger than that of the first recording medium, such as thick paper or special media, and the set temperature of the fixing device 20 in the second job is at least in the case of the first job. Set higher than.

FIG. 3 is an explanatory diagram of productivity when a second job (printing of 5 thick papers) is printed between consecutive first jobs (printing of 100 thin papers). Here, it is assumed that a job of 5 thick papers (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) is described. The same can be considered when printing a job (second job) of five thick sheets in the middle of a job).

FIG. 3A is an explanatory diagram of productivity in the case of controlling the fixability to be kept 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. It ends up.

On the other hand, in FIG. 3B, the set temperature is not changed and remains the set temperature in the first job, and the fixing device 20 is fixed by slowing the linear speed in the paper passing in the second job. It is explanatory drawing of productivity in the case of controlling to keep the sex constant. When the linear speed is changed without changing the set temperature between the first job and the second job, downtime for temperature tracking becomes unnecessary. At this time, the paper passing time of the thick paper increases and the downtime for changing the line speed is required. However, since the number of printed sheets of the thick paper is small, the influence is small and the downtime is short. It is possible to suppress a decrease in productivity as compared with the case of (A).

That is, as shown in FIG. 3, in a job having a relatively small number of pages of the second job (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 switching the set temperature to (thin paper), it can be said that the productivity does not decrease 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 having a relatively large number of prints is printed between the first jobs will be described. FIG. 4 is an explanatory diagram of productivity when a second job (printing of 80 sheets of thick paper) is printed between consecutive first jobs (printing of 100 sheets of thin paper). Similar to FIG. 3, FIG. 4A shows the fixing device 20 when the set temperature is changed according to the recording medium, and FIG. 4B shows the fixing device 20 in the paper passing in the second job without changing the set temperature. It is explanatory drawing of productivity at the time of changing the line speed of.

Unlike the case shown in FIG. 3, as in the example shown in FIG. 4, when the number of printed sheets of the second job (thick paper) increases, as shown in FIG. 4 (B), when the linear speed is slowed down, the second job (thick paper) is second. The effect of productivity reduction during job (thick paper) printing becomes large, and 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 having a relatively large number of pages of the second job (thick paper), if the linear speed is slowed down in the second job, the effect 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, while the first job using the first recording medium (for example, thin paper) is continuously printed, the second job using the second recording medium (for example, thick paper) is printed. In a predetermined print mode (for example, bookbinding mode) in which printing is executed, a determination unit (determination unit 32, S103 in FIG. 5) for determining the number of prints of the second job and a predetermined number of prints (N1) or less. In a certain case, the linear speed control unit (linear speed control unit 33, S104 in FIG. 5) that changes the linear speed of the fixing device (fixing device 20) between the first job and the second job, and the number of printed sheets are a predetermined number. When the number exceeds the limit, a set temperature control unit (set temperature control unit 34, S105 in FIG. 5) for changing the set temperature of the fixing device between the first job and the second job is provided. In addition, the code in parentheses and the application example are shown.

FIG. 5 is a flowchart showing an example of control by the control unit 31 when passing mixed jobs.

First, it is determined whether the mode 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 T1 or more higher than the set temperature of the first job (S102).

When the set temperature is higher than T1 (S102: Yes), it is determined whether or not the number of prints of the second job is N1 or less of the predetermined number (S103). When the number of printed sheets of the second job is N1 or less of the predetermined number of sheets (S103: Yes), the set temperature in the second job is not changed, and the control for slowing down the linear speed is performed (S104).

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

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

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

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

Further, as shown in (c), when the set temperature in the first job is 150 ° C. and 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 it is as follows, since the set temperature is the first set temperature + 15 ° C. and is T1 or less, the linear velocity in the second job is not changed.

Further, as shown in (d), when the set temperature in the first job is 150 ° C. and the number of printed sheets is 100, the set temperature in the second job is 165 ° C. and the number of printed sheets is 30, the set temperature is the first. Since the set temperature of one is + 15 ° C., it is T1 or less, and the number of printed sheets exceeds N1, so the linear velocity 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 printing jobs including switching of recording media with different paper types and thicknesses, such as mixed jobs of relatively small number of thick paper and large number of thin papers and mixed jobs of special media. It can be suppressed.

Hereinafter, a more preferable embodiment of the fixing device according to the present embodiment will be described. It is preferable that the predetermined print mode for executing the linear speed change control at the time of passing the mixed job described so far can be set by the user. Further, 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. An example of setting by the user will be described below.

The control unit 31 causes the operation panel 35 of the image forming apparatus 100 to display each setting screen shown in FIG. 6, 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 change the settings of each job 71 to 73 to set the paper type paper thickness information of each job.

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

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

As shown in Table 2, the larger the difference between the set temperatures, the larger the linear velocity adjustment value and the smaller the value of the predetermined number of sheets N1 to obtain more suitable control.

Specific control examples 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. and 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. Since the set temperature is + 35 ° C., the linear velocity is -60%.

Further, as shown in (b), when the set temperature in the first job is 135 ° C. and 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 the first. One set temperature + 35 ° C. In this case, since the predetermined number of sheets N1 = 6 sheets is exceeded, the linear velocity is not changed.

Further, as shown in (c), when the set temperature in the first job is 150 ° C. and 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 the first. Since the set temperature is + 20 ° C, the linear velocity is -30%.

Further, as shown in (d), 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 155 ° C., and the number of printed sheets is 2, the set temperature is the second. Since the set temperature is + 5 ° C, the linear velocity is not changed.

Further, it is more preferable that the line speed adjustment value is different between the case of color printing and the case of monochrome printing. Table 4 shows an example of setting the line speed adjustment values for color printing and monochrome printing.

The linear speed adjustment values shown in Table 4 are applied when the linear velocity is changed in the second job, and the determined linear velocity adjustment values are further adjusted in the monochrome mode. This is because in the monochrome mode as compared with the color mode, the amount of toner adhered is small, so that the 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 velocity adjustment control, if possible, only the linear velocity of the fixing device 20 may be changed instead of the overall linear velocity of the image forming apparatus 100. For example, in the image forming apparatus 100 having a relatively slow linear velocity, when the linear velocity adjustment value is small, only the linear velocity in the fixing apparatus 20 may be changed instead of the linear velocity of the entire apparatus.

It should be noted that the above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be carried out without departing from the gist of the present invention.

10 Intermediate transfer belt 11 Tandem type image forming unit 12 Exposure device 13 Secondary transfer device 14 Support roller 15 Support roller 15'Support roller 16 Secondary transfer Opposing roller 16' Secondary transfer roller 17 Cleaning device 18 Image forming means 20 Fixing device 21 Heating roller 22 Fixing roller 23 Pressurizing roller 24 Fixing belt 25 Heater 26 Heater 27 Tension roller 28 Separation plate 29 Separation plate 30 Temperature sensor 31 Control unit 32 Judgment unit 33 Line speed control unit 34 Set temperature control unit 35 Operation panel 37 Roller 38 Conveyance belt 39 Sheet reversing device 40 Photoreceptor drum 42 Paper feed roller 43 Paper bank 44 Paper feed tray 45 Separation roller 46 Paper feed path 47 Transport roller vs. 48 Paper feed path 49 Positioning roller vs. 50 Paper feed roller 51 Manual feed tray 52 Separation Roller 53 Manual paper feed path 56 Discharge roller 57 Discharge tray 62 Primary transfer roller 63 Backup roller 100 Image forming device 200 Paper feed table T Unfixed toner image P Recording medium

JP-A-2010-190914 Japanese Unexamined Patent Publication No. 2013-231803

Claims (8)

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 that determines the number of prints of the second job, and
A linear speed control unit that changes the linear velocity 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 set temperature control unit for changing 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 of sheets is provided .
The determination unit determines whether 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 control unit is the first when the set temperature of the second job is higher than the set temperature of the first job by a predetermined temperature or more and the number of printed sheets is equal to or less than the predetermined number of sheets. A fixing device characterized in that the linear velocity is changed to a different value according to the difference between the set temperature of one job and the set temperature of the second job. The second recording medium has a larger heat capacity than the first recording medium.
The fixing device according to claim 1 , wherein the linear speed control unit makes the linear speed at the time of passing the second job slower than that at the time of passing the first job. The determination unit, according to the difference of the first job of the set temperature and the second job set temperature, the fixing device according to claim 1, characterized in that to change the predetermined number. The fixing device according to any one of claims 1 to 3, 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 any one of claims 1 to 4 , wherein the set temperature is determined based on the paper type paper thickness information of the recording medium used for each job set by the user. The fixing device according to any one of claims 1 to 5 , wherein the predetermined print mode can be set by a user. An image forming apparatus comprising the fixing apparatus according to any one of claims 1 to 6. 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.
Judgment processing for determining the number of prints of the second job and
When the number of printed sheets is less than or equal to a predetermined number, a linear speed control process for changing the linear velocity of the fixing device between the first job and the second job, and
When said number of printed sheets exceeds a predetermined number, you have rows and setting the temperature control process, the changing the setting temperature of the fixing device between the first job and the second job,
In the determination process, it is determined whether the set temperature of the second job is higher than the set temperature of the first job by a predetermined temperature or more.
In the linear speed control process, when the set temperature of the second job is higher than the set temperature of the first job by a predetermined temperature or more and the number of printed sheets is equal to or less than the predetermined number of sheets, the first A control method of an image forming apparatus, characterized in that the linear velocity is changed to a different value according to the difference between the set temperature of one job and the set temperature of the second job.

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