Image forming apparatus

Abstract

To suppress reduction in the number of prints per unit time in a job in which recording materials with different basis weights are mixed.SOLUTION: A fixing device comprises a heating rotating body that applies heat to a recording material, and a pressure rotating body, and the rotating bodies apply heat and a pressure to the recording material. The fixing device can convey the recording material at a plurality of speeds including a first speed and a second speed, and the second speed is faster than the first speed. A job in which recording materials with different basis weight are mixed is defined as a mixed job. In the mixed job, one mode can be executed from a plurality of modes including a first mode and a second mode. When the first mode is executed in the mixed job, the recording material with first basis weight is conveyed at the second speed, and the recording material with second basis weight is conveyed at the first speed. When the second mode is executed in the mixed job, the recording material with the first basis weight and the second recording material are conveyed at the first speed.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a fixing device for fixing a toner image on a recording material.

Background Art

[0002] An image forming apparatus has a fixing device for fixing an unfixed toner image on a recording material.

[0003] A fixing device having a heating rotating body with a heat source for heating an unfixed toner image and a pressure roller for pressing the heating rotating body is known (Patent Document 1). The fixing device also has a contact-separation mechanism, and the contact-separation mechanism enables the pressure rotating body to move between a position where it contacts the heating rotating body and a position where it is separated from the heating rotating body. When the pressure rotating body is in a position where it contacts the heating rotating body, a nip portion is formed by the heating rotating body and the pressure rotating body. When a recording material carrying an unfixed toner image is conveyed to this nip portion, heat and pressure necessary for fixing are applied in the nip portion, and the toner on the recording material is fixed.

[0004] When forming a toner image on a recording material, the amount of heat required for fixing the toner image varies depending on the type of the recording material. Therefore, the temperature of the heating rotating body is changed according to the type of the recording material. As a result, the amount of heat applied to the toner image on the recording material is appropriately controlled.

[0005] When changing to an optimal amount of heat according to the type of the recording material, the image quality of the toner image formed on the recording material is improved. On the other hand, when the temperature is changed for each recording material, productivity decreases. Therefore, with a fixing device having a picture quality priority mode and a productivity priority mode, a user can select a mode to be used for fixing according to the purpose of use (Patent Document 1).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] When fixing the toner image, the transport speed needs to be changed according to the basis weight of the recording material. The larger the basis weight of the recording material, the greater the amount of heat required for fixing. Conversely, the smaller the basis weight of the recording material, the less heat is required for fixing. Therefore, one possible method is to increase the transport speed for recording materials with a small basis weight and decrease the transport speed for recording materials with a large basis weight, thereby supplying the recording material with the amount of heat required for fixing according to its basis weight.

[0008] However, in jobs involving a mix of recording materials with different basis weights, the material transport speed had to be switched each time the basis weight changed. This could potentially reduce the number of prints per unit time.

[0009] Therefore, the fixing device according to the present invention aims to suppress a decrease in the number of printed sheets per unit time in jobs in which recording materials with different basis weights are mixed. [Means for solving the problem]

[0010] In view of the above problems, the image forming apparatus according to the present invention comprises a heating rotating body that heats a recording material, a pressurizing rotating body that pressurizes the heating rotating body, a control unit which controls the transport speed of the recording material and which uses the heating rotating body and the pressurizing rotating body to apply heat and pressure to the recording material and fix a toner image to the recording material, and an acquisition unit which acquires information regarding the basis weight of the recording material, wherein the control unit A mixed job for forming toner images on multiple recording materials, including a recording material with a first basis weight and a recording material with a second basis weight greater than the first basis weight, in which case the mixed job is performed in which the basis weight of the first recording material is the first basis weight and the basis weight of the second recording material is the second basis weight, The aforementioned mixed The basis weight information of the first job, and the aforementioned mixed Based on the basis weight information of the second sheet of the job, mixed The transport speed for transporting the first recording material of the job is set to a first predetermined speed, and the mixed The basis weight information of the first job, and the aforementioned mixed Based on the basis weight information of the second sheet of the job, mixedA first mode in which the transport speed for transporting the second recording material of the job is set to the first predetermined speed, A mixed job for forming toner images on a plurality of recording materials, including a recording material with a first basis weight and a recording material with a second basis weight greater than the first basis weight, in which case the mixed job is performed in which the basis weight of the first recording material is the first basis weight and the basis weight of the second recording material is the second basis weight, The aforementioned mixed Based on the basis weight information of the second sheet of the job, mixed Based on the basis weight information of the first job, mixed The transport speed of the first recording material of the job is set to a second predetermined speed which is greater than the first predetermined speed, and the mixed Based on the basis weight information of the first job, mixed Based on the basis weight information of the second sheet of the job, mixed The system is characterized by the ability to selectively execute one mode from a plurality of modes, including a second mode in which the transport speed of the second recording material of the job is set to the first predetermined speed. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress the decrease in the number of printed pages per unit time. [Brief explanation of the drawing]

[0012] [Figure 1] This is a diagram showing the configuration of the image processing system in this embodiment. [Figure 2] This is a system configuration diagram of this embodiment. [Figure 3] This is a schematic diagram of the image forming apparatus in this embodiment. [Figure 4] This is a schematic diagram of the fixing device in this embodiment. [Figure 5] This is a diagram of the screen used to set the mode. [Figure 6] This is a table showing the relationship between basis weight, transport speed, and fixing temperature for each mode. [Figure 7] This is a flowchart of this embodiment. [Figure 8] This is a flowchart for retrieving page information. [Figure 9] This is a flowchart for determining the transport speed on the first page. [Figure 10] This is a flowchart for determining the transport speed during a job. [Figure 11] It is a diagram of a screen for setting the number of pages to be acquired. [Figure 12] It is a conceptual diagram of page information. [Figure 13] It is a table showing the relationship between the basis weight, conveyance speed, and fixing temperature in Example 2. [Figure 14] It is a flowchart for determining the conveyance speed of the first sheet in the example.

Mode for Carrying Out the Invention

[0013] [[ID=G19]]<Example 1> <Image Processing System> FIG. 1 is a configuration diagram of an image processing system including an image forming apparatus 101 according to the present embodiment. The image processing system includes an image forming apparatus 101 and an external controller 102. The image forming apparatus 101 is, for example, a multifunction machine, a multi-function peripheral (MFP), or the like. The external controller 102 is, for example, an image processing controller, a digital front end (DFE), a print server, or the like. [[ID=G25]]

[0014] [[ID=G26]] [[ID=G27]]The image forming apparatus 101 and the external controller 102 are communicably connected via an internal LAN (Local Area Network) 105 and a video cable 106. The external controller 102 is connected to a client PC (Personal Computer) 103 via an external LAN 104. The external controller 102 acquires a print instruction (print job) from the client PC 103.

[0015] The client PC 103 has a printer driver installed that has the function of converting image data into a print description language that can be processed by the external controller 102. Users can instruct printing via the printer driver using various applications. The printer driver sends image data to the external controller 102 based on the print job from the user. The external controller 102 receives the print job containing image data from the client PC 103, performs data analysis and rasterization processing, and instructs the image forming apparatus 101 to print (form an image) based on the image data.

[0016] The image forming apparatus 101 is configured by connecting multiple devices having different functions, including a printing device 107, and is capable of complex printing processes such as bookbinding. The image forming apparatus 101 of this embodiment includes a printing device 107 and a finisher 109. The printing device 107 forms an image on recording material fed from a paper feed section located at the bottom of the main body using a developer (e.g., toner). The printing device 107 forms images of yellow (Y), magenta (M), cyan (C), and black (K). A full-color image is formed on the recording material by superimposing images of each color. The recording material on which the image has been formed is transported from the printing device 107 to the finisher 109. The finisher 109 loads the recording material on which the image has been formed.

[0017] This image processing system is configured with an external controller 102 connected to the image forming apparatus 101, but the external controller 102 is not necessarily required. For example, the image forming apparatus 101 may be configured to directly acquire print jobs containing image data from a client PC 103 via an external LAN 104. In this case, the image forming apparatus 101 would perform the data analysis and rasterization processing that is done by the external controller 102. In other words, the image forming apparatus 101 and the external controller 102 may be configured as a single unit.

[0018] <System Configuration> Figure 2 is a system configuration diagram showing the control of the image processing system. Here, the controllers that control the operation of the image forming apparatus 101, the external controller 102, and the client PC 103 are described.

[0019] <Printing device> The printing device 107 includes a communication interface (I / F) 217, a LAN I / F 218, and a video I / F 220 for communication with other devices. The printing device 107 includes a CPU (Central Processing Unit) 222, memory 223, storage 221, and an image processing unit 232 for controlling the operation of the printing device 107. The printing device 107 includes an exposure unit 227, an imaging unit 228, a fixing unit 311, and a paper feeding unit 230 for forming an image. The printing device 107 includes an operation unit 224 and a display 225 as a user interface. The printing device 107 includes a timer 251 and a temperature sensor 252 for adjusting correction values ​​to optimally correct the geometric characteristics of the images on the front and back surfaces. Here, the geometric characteristics of the image include, for example, perpendicularity and the printing position of the image on the recording material. These components are connected to each other so as to be able to communicate with each other via a system bus 233.

[0020] The communication interface 217 is connected to the finisher 109 via the communication cable 249 and controls communication with the finisher 109. When the printer 107 and the finisher 109 operate in cooperation, information and data are sent and received via the communication interface 217. The LAN interface 218 is connected to the external controller 102 via the internal LAN 105 and controls communication with the external controller 102. The printer 107 receives print settings from the external controller 102 via the LAN interface 218. The video interface 220 is connected to the external controller 102 via the video cable 106 and controls communication with the external controller 102. The printer 107 receives image data representing the image to be formed from the external controller 102 via the video interface 220.

[0021] The CPU 222 comprehensively controls image processing and printing by executing computer programs stored in the storage 221. The memory 223 provides a work area for the CPU 222 to perform various processes. When performing image forming processing, the CPU 222 controls the exposure unit 227, the image formation unit 228, the fixing device 311, and the paper feeding unit 230.

[0022] The exposure unit 227 includes a photoreceptor, a charging wire for charging the photoreceptor, and a light source for exposing the photoreceptor, which has been charged by the charging wire, in order to form an electrostatic latent image on the photoreceptor. The photoreceptor is, for example, a photosensitive belt with a photosensitive layer formed on the surface of a belt-shaped elastic member, or a photosensitive drum with a photosensitive layer formed on the surface of a cylinder. Alternatively, a charging roller may be used instead of the charging wire. The exposure unit 227 charges the surface of the photoreceptor to a uniform negative potential using the charging wire. The exposure unit 227 outputs laser light from the light source based on image data. The laser light scans the surface of the uniformly charged photoreceptor. As a result, the potential of the photoreceptor fluctuates at the position irradiated by the laser light, and an electrostatic latent image is formed on the surface. Four photoreceptors are provided, corresponding to four colors: yellow (Y), magenta (M), cyan (C), and black (K). Electrostatic latent images corresponding to different colored images are formed on each of the four photoreceptors.

[0023] The image-forming unit 228 transfers the toner image formed on the photoreceptor to the recording material. The image-forming unit 228 includes a developer, a transfer unit, and a toner supply unit. The developer forms a toner image by attaching negatively charged toner from a developing cylinder to the electrostatic latent image formed on the surface of the photoreceptor. There are four developers, one for each of the four colors: yellow (Y), magenta (M), cyan (C), and black (K). The developer makes the electrostatic latent image on the photoreceptor visible using the corresponding color toner.

[0024] The transfer unit has an intermediate transfer belt 308, which transfers the toner image from the photoreceptor to the intermediate transfer belt 308. A primary transfer roller is provided at a position opposite the photoreceptor, with the intermediate transfer belt 308 in between. When a positive potential is applied to the primary transfer roller, toner images from each of the four photoreceptors are superimposed and transferred onto the intermediate transfer belt. This forms a full-color toner image on the intermediate transfer belt. The toner image formed on the intermediate transfer belt is then transferred to the recording material by a secondary transfer roller, which will be described later. When a positive potential is applied to the secondary transfer roller, it transfers the full-color toner image from the intermediate transfer belt 308 to the recording material.

[0025] The fixing device 311 fixes the transferred toner image onto the recording material. The fixing device 311 has a heater and a pair of rollers. The fixing device 311 heats and pressurizes the toner image on the recording material with the heater and the pair of rollers, melting and fixing the toner image to the recording material. This produces a finished product in which an image has been formed on the recording material. The paper feeding unit 230 is equipped with transport rollers and various sensors in the transport path and controls the feeding operation of the recording material.

[0026] The operation unit 224 is an input device that receives various settings and operation instructions from the user. The operation unit 224 consists of various input keys and a touch panel. The display 225 is an output device that displays setting information of the image forming apparatus 101 and the processing status (status information) of print jobs.

[0027] Timer 251 counts time. CPU 222 obtains the current date and time based on the count value of Timer 251. Temperature sensor 252 measures the internal temperature of the printing machine 107. CPU 222 obtains the internal temperature, which is one of the environmental conditions, based on the measurement result of Temperature sensor 252. In addition to temperature, humidity may also be obtained as an environmental condition.

[0028] <Finisher> The finisher 109 performs stapling on the output from, for example, the printing device 107. The finisher 109 includes a communication interface 241, a CPU 242, a memory 243, and a paper discharge control unit 244. These components are connected to each other via a system bus 245 so that they can communicate with one another. The communication interface 241 is connected to the printing device 107 via a communication cable 249 and controls communication between the finisher 109 and the printing device 107. When the finisher 109 and the printing device 107 work together, information and data are sent and received via the communication interface 241. The CPU 242 executes a control program stored in the memory 243 and performs various controls necessary for paper discharge. The memory 243 stores the control program. The memory 243 also provides a work area for the CPU 242 when it performs various processes. The paper discharge control unit 244 discharges the transported recording material based on instructions from the CPU 242.

[0029] <External Controller> The external controller 102 includes a LAN I / F 213, a LAN I / F 214, and a video I / F 215 for communication with other devices. The external controller 102 includes a CPU 208, memory 209, and storage 210 to control the operation of the external controller 102. The external controller 102 includes a keyboard 211 and a display 212 as a user interface. These components are connected to each other so as to be able to communicate with each other via a system bus 216.

[0030] LAN I / F 213 is connected to the client PC 103 via the external LAN 104 and controls communication with the client PC 103. The external controller 102 obtains print jobs from the client PC 103 via LAN I / F 213. LAN I / F 214 is connected to the printer 107 via the internal LAN 105 and controls communication with the printer 107. The external controller 102 sends print settings to the printer 107 via LAN I / F 214. Video I / F 215 is connected to the printer 107 via video cable 106 and controls communication with the printer 107. The external controller 102 sends image data to the printer 107 via video I / F 215.

[0031] The CPU 208 comprehensively performs processing such as receiving image data transmitted from the client PC 103, RIP processing, and transmitting image data to the image forming apparatus 101 by executing computer programs stored in the storage 210. The memory 209 provides a work area for the CPU 208 to perform various processes. The keyboard 211 is an input device that accepts various settings inputs and operation instructions from the user. The display 212 is an output device that displays information of the application being executed by the external controller 102 as still images or videos.

[0032] <Client PC> The client PC 103 includes a CPU 201, memory 202, storage 203, keyboard 204, display 205, and LAN I / F 206. These components are interconnected and can communicate with each other via a system bus 207.

[0033] The CPU 201 controls the operation of the client PC 103 by executing computer programs stored in the storage 203. In this embodiment, the CPU 201 performs image data creation and print job transmission processing. The memory 202 provides a work area for the CPU 201 to perform various processes. The keyboard 204 and display 205 are the user interface. The keyboard 204 is an input device that receives instructions from the user. The display 205 is an output device that displays information about the application being executed on the client PC 103 as still images or videos. The LAN I / F 206 is connected to the external controller 102 via the external LAN 104 and controls communication with the external controller 102. The client PC 103 sends a print job including image data to the external controller 102 via the LAN I / F 206.

[0034] The external controller 102 and the image forming apparatus 101 are connected by an internal LAN 105 and a video cable 106, but any configuration that allows for the transmission and reception of data necessary for printing is acceptable, and for example, they may be connected by only the video cable 106. Memories 202, 209, 223, and 243 can each be storage devices for holding data and programs. These memories can be, for example, volatile RAM (Random Access Memory), non-volatile ROM (Read Only Memory), storage, USB (Universal Serial Bus) memory, etc.

[0035] <Configuration of an image forming apparatus> Figure 3 is a diagram showing the configuration of the image forming apparatus 101. A display 225 is provided above the printing apparatus 107. The display 225 displays information for the printing status and settings of the image forming apparatus 101. The recording material (product) on which the image has been formed by the printing apparatus 107 is transported to the finisher 109 located downstream.

[0036] The printing apparatus 107 includes a paper feeding section 230 comprising multiple paper feeding decks 301, 302 and a transport path 303. Each paper feeding deck 301, 302 can accommodate different types of recording material. Information about the stored recording material (basis weight, type of recording material, etc.) can be detected by the apparatus, and in this embodiment, it is configured to be configurable by the user via the display 225.

[0037] The recording material contained in each paper feed deck 301, 302 is separated into uppermost sheets and fed to the transport path 303. The printing device 107 includes image forming units 304, 305, 306, and 307 as an exposure unit 227 for forming an image. The printing device 107 forms a color image. To this end, the image forming unit 304 forms a black (K) image (toner image). The image forming unit 305 forms a cyan (C) image (toner image). The image forming unit 306 forms a magenta (M) image (toner image). The image forming unit 307 forms a yellow (Y) image (toner image).

[0038] The printing apparatus 107 includes an image-forming unit 228, an intermediate transfer belt 308 and a secondary transfer roller 309 onto which toner images are transferred from each of the image-forming units 304, 305, 306, and 307. The intermediate transfer belt 308 rotates clockwise in the figure, and toner images are superimposed and transferred in the order of image-forming unit 307, image-forming unit 306, image-forming unit 305, and image-forming unit 304. This forms a full-color toner image on the intermediate transfer belt 308. As the intermediate transfer belt 308 rotates, it transports the toner image to the secondary transfer roller 309. The recording material is transported to the secondary transfer roller 309 at the same time that the toner image is transported to the secondary transfer roller 309. The secondary transfer roller 309 transfers the toner image on the intermediate transfer belt 308 onto the transported recording material.

[0039] The printing apparatus 107 includes a fixing device 311. The fixing device 311 fixes the toner image onto the recording material. For this purpose, the fixing device 311 includes a heating rotating body and a pressurizing rotating body. The recording material is subjected to heat and pressure as it passes through the nip section N formed by the heating rotating body and the pressurizing rotating body. As a result, the toner image is melted and pressed onto the first surface of the recording material.

[0040] The recording material that has passed through the fixing device 311 is guided to the transport path 315. If double-sided printing is instructed, an image is also formed on the reverse side (second side). Therefore, the recording material is guided to the reversal path 316. The recording material transported to the reversal path 316 has its transport direction reversed and is transported to the double-sided transport path 317. The recording material is reversed front to back by switchback transport in the reversal path 316 and the double-sided transport path 317. The recording material is transported to the transport path 303 by the double-sided transport path 317, and as it passes through the secondary transfer roller 309 and the fixing device 311, an image is formed on the second side, which is different from the first side.

[0041] In the case of single-sided printing, or when an image is formed on both sides in double-sided printing, the recording material is transported to the transport path 315 and handed over to the finisher 109.

[0042] The finisher 109 can load recording material received from the printing device 107. The finisher 109 includes a transport path 331 and a stack tray 332 for loading the recording material. Transport sensors 333, 334, 335, and 336 are provided in the transport path 331. The recording material transported from the printing device 107 is loaded onto the stack tray 332 via the transport path 331. The transport sensors 333, 334, 335, and 336 detect the passage of the recording material being transported along the transport path 331. If the CPU 242 determines that a transport jam (transport abnormality) has occurred in the finisher 109 if the leading or trailing end of the recording material in the transport direction is not detected by the transport sensors 333, 334, 335, or 336 even after a predetermined time has elapsed since the start of transport of the recording material. In this case, the CPU 242 notifies the printing device 107 that a transport jam has occurred.

[0043] <Fusing device> Next, the details of the fixing device configuration in this embodiment will be described using Figure 4. Figure 4 is a cross-sectional view of the fixing device in this embodiment. In Figure 4, the recording material is transported from right to left on the paper. The fixing device 311 has a heating unit 410 having a heat source and a pressurizing rotating body (hereinafter referred to as a pressurizing roller) 402 that forms a nip portion N together with the heating unit 410. The heating unit 410 has a fixing belt (hereinafter referred to as a belt) 401 as an endless and rotatable heating rotating body, a pad member (hereinafter referred to as a pad) 403 as a fixing member, a heating roller 404 and a steering roller 405.

[0044] The belt 401 has thermal conductivity and heat resistance, and is a thin-walled cylindrical shape. In this embodiment, it has a three-layer structure with a base layer, an elastic layer on the outer circumference of the base layer, and a release layer on the outer circumference of the elastic layer. The base layer is 60 μm thick and made of polyimide resin (PI), the elastic layer is 300 μm thick and made of silicone rubber, and the release layer is 30 μm thick and made of PFA (polytetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin. The belt 401 is stretched by a pad 403, a heating roller 404, and a steering roller 405.

[0045] The pad 403 is a component that presses against the pressure roller 402 via the belt 401 to form a nip portion N of a predetermined width in the recording material transport direction. Its cross-section is approximately rectangular, and it is a long component along the width direction of the belt 401. The material of the pad 403 needs to be heat resistant, and LCP (liquid crystal polymer) resin is used.

[0046] A sliding sheet 407, whose surface is coated with PTFE, and silicone oil S (hereinafter referred to as oil S) are interposed between the pad 403 and the belt 401, so that the belt 401 slides smoothly against the pad 403.

[0047] The sliding sheet 407 is formed by coating the surface of a 70 μm thick polyimide substrate with PTFE. The sliding sheet 407 is positioned to improve the sliding properties of the pad 403 and the belt 401, and it is possible to substitute the sliding sheet 407 with a coating that improves sliding properties applied to the surface of the pad 403.

[0048] A stay 406 is positioned inside the belt 401. The stay 406 is located on the side opposite to the sliding seat 407, inside the pad 403. The stay 406 is a rigid reinforcing member that is long in the width direction of the belt 401 and backs up the pad 403. It is made of 3mm thick extruded SUS304 material, and its strength is ensured by forming the cross-section into a hollow "square" shape. When the pad 403 is pressed against the pressure roller 402, the stay 406 provides strength to the pad 403 and ensures the applied pressure at the nip portion N. Note that the material of the stay 406 is not limited to stainless steel as long as strength can be ensured.

[0049] The heating roller 404 is a 1 mm thick stainless steel pipe with a halogen heater (not shown) installed inside, capable of generating heat up to a predetermined temperature. The belt 401 is heated by the heating roller 404 and controlled to a fixing temperature according to the paper type based on temperature detection by a thermistor. The thermistor is not limited to detecting the surface temperature of the heating roller 404; it may also detect the surface temperature of the belt 401. Furthermore, the heating roller 404 may be configured to rotate. By rotating the heating roller 404, it is possible to increase the tension of the belt 401 from the nip section N to the heating roller 404 in the belt rotation direction. This allows for an increase in the curvature of the nip section N exit in the belt rotation direction, thereby improving the separation performance of the recording material P. In this embodiment, the fixing temperature refers to the surface temperature of the heating roller 404. However, it is not limited to this. It may also be the temperature of the heating roller 404 detected by the thermistor, or the temperature of the belt 401.

[0050] The steering roller 405 suspends the belt 401 and is supported by the steering frame 413. As the steering frame 413 rotates, the steering roller 405 changes its alignment with respect to other suspension members. This creates a tension difference between the front and rear of the belt 401, controlling the position of the belt 401 in the width direction. The steering roller 405 is biased by a spring supported by the steering frame 413 and also acts as a tension roller, applying a predetermined tension to the belt 401.

[0051] The pressure roller 402 is a roller with an elastic layer formed on the outer circumference of its shaft and a release layer formed on the outer circumference of the elastic layer. The shaft is made of stainless steel, the elastic layer is made of conductive silicone rubber with a thickness of 5 mm, and the release layer is made of PFA as a fluororesin with a thickness of 50 μm. The pressure roller 402 is supported by the frame of the fixing device 311, and a gear is fixed to one end, which is connected to the drive source M to rotate it. The belt 401 is driven to rotate in the R direction by being sandwiched between the rotating pressure roller 402 and the pad 403.

[0052] As described above, a pad 403, a heating roller 404, and a steering roller 405 are arranged on the inner circumferential surface of the belt 401, suspending the belt 401. The belt 401 is held between the pressure roller 402 and the pad 403, and rotates as the pressure roller 402 is driven. The belt 401 stores heat from the heating roller 404. When the recording material carrying the unfixed toner image is held and conveyed by the pressure roller 402 and the belt 401 at the nip section N, the heat and pressure necessary for fixing are applied. As a result, the toner image is fixed onto the recording material P.

[0053] <Relationship between basis weight and conveying speed> In this embodiment, the image forming apparatus 101 can transport the recording material at multiple speeds, including a first speed and a second speed, as the transport speed when the recording material passes through the secondary transfer roller 309 and the fixing device 311. In this embodiment, the first speed is a low speed of 400 mm / s, and the second speed is a high speed of 600 mm / s. Although two speeds are given as an example here, the recording material may be transported at three or more speeds.

[0054] Furthermore, the image forming apparatus 101 in this embodiment is capable of forming images on recording materials with both large and small basis weights. Here, the recording material with the small basis weight is referred to as the first basis weight recording material, and the recording material with the large basis weight is referred to as the second basis weight recording material.

[0055] This embodiment explains why the recording material is transported at multiple speeds. The larger the basis weight of the recording material, the greater its heat capacity. The larger the basis weight of the recording material, the greater the amount of heat required to fix the toner image. The faster the transport speed of the recording material, the shorter the time the recording material is heated at the nip section N. Therefore, when recording material with a large basis weight is transported at high speed, fixation may not be guaranteed. Thus, in order to guarantee the fixation of recording material with a large basis weight, a low transport speed is provided in addition to a high transport speed. Furthermore, in order to guarantee high image quality, it is necessary to increase the time the heat is applied at the nip section N.

[0056] At the high speed of 600 mm / s (second speed), certain image quality cannot be achieved with some recording materials, such as recording materials with a small basis weight (first speed). Therefore, by having a low transport speed of 400 mm / s (first speed), it is possible to achieve certain image quality for recording materials with a large basis weight (second speed). Furthermore, consistent fixing performance and image quality are achieved by changing the transport speed and fixing temperature (set temperature) for each recording material. The image forming apparatus 101 can receive page information from the external controller 102 before feeding paper. This information includes the paper feed deck where the recording material to be fed is stored, the size of the recording material, the type of recording material (such as coated paper or embossed paper), the basis weight of the recording material, and whether or not it is the last page of the job. The transport speed and fixing temperature are further determined by the basis weight. More specific basis weight, transport speed, and fixing temperature are determined by the user selecting the operating mode. In this embodiment, the transport speed and fixing temperature are determined when the basis weight is determined, but the transport speed and fixing temperature may be determined by a different method. For example, the transport speed and fixing speed may be determined by the size and type of recording material.

[0057] For recording materials with a large basis weight, high-speed transport and fixing are performed. Conversely, for recording materials with a small basis weight, low-speed transport and fixing are performed. The transport speed is adjusted according to the basis weight of the recording material.

[0058] When executing a mixed job, which involves a mix of recording materials with small and large basis weights, there was a risk of a decrease in the number of printed sheets per unit time (productivity). This was due to the switching time required to change the transport speed. In a mixed job, the transport speed was changed each time the basis weight of the recording material changed. Specifically, when changing from a small basis weight to a large basis weight, the transport speed of the recording material had to be changed from high speed to low speed to ensure proper fixing. Approximately 30 seconds are required to switch the transport speed. Therefore, this transport speed switching time results in downtime. Since the transport speed switching occurs each time the basis weight of the recording material changes, there was a risk of a decrease in productivity in mixed jobs. Therefore, the fixing device of this embodiment can suppress the decrease in productivity by suppressing the switching time of the transport speed of the recording material in mixed jobs. The details are described below.

[0059] First, the printing modes provided by the fuser 311 of this embodiment will be described. The fuser 311 has a productivity priority mode and an image quality priority mode. Specifically, it has multiple modes, including a productivity priority 1 mode, a productivity priority 2 mode, and an image quality priority mode. The user can set the operating modes related to the basis weight, transport speed, and fixing temperature as described above using the setting screen displayed on the display 225 by the CPU 222. Figure 5(a) is the initial screen. When the user selects the "Advanced Mode" soft key from the initial screen, the CPU 222 displays the advanced mode selection screen shown in Figure 5(b) on the display 225. When the user selects the "Speed / Image Quality" soft key from the advanced mode selection screen, the CPU 222 displays the speed / image quality priority adjustment setting screen shown in Figure 5(c) on the display 225.

[0060] When the user sets productivity priority 1 as shown in Figure 5(c-1) and presses "OK", the image formation operation is performed according to the relationship between basis weight, transport speed, and fixing temperature shown in Figure 5(a). In this mode, recording materials with a basis weight of 400 gsm or less can be printed at either a speed of 600 mm / s or 400 mm / s. Which speed is used for printing when this mode is set will be explained later in "Printing Speed ​​Switching Control". When the user sets productivity priority 2 as shown in Figure 5(c-2) and presses "OK", the image formation operation is performed according to the relationship between basis weight, transport speed, and fixing temperature shown in Figure 6(b). Recording materials with a basis weight of 400 gsm or less are printed at a transport speed of 600 mm / s. As a result, in productivity priority 1 mode, recording materials with a basis weight of 400 gsm or less were transported at speeds of 600 mm / s and 400 mm / s. This may result in slight variations in fixing performance and image quality between transport at 600 mm / s and transport at 400 mm / s. However, in Productivity Priority 2 mode, compared to Productivity Priority 1 mode, recording materials of 400 gsm or less are transported at 600 mm / s, which reduces the likelihood of inconsistencies in fixing performance and image quality. When the user sets the Image Quality Priority mode shown in Figure 5(c-3) and presses "OK", the image formation operation is performed according to the relationship between basis weight, transport speed, and fixing temperature shown in Figure 6(c). By precisely controlling the fixing temperature for recording materials of 400 gsm or less, it is possible to print images with even better image quality than in Productivity Priority 1 and Productivity Priority 2 modes. The processing for Productivity Priority 2 and Image Quality Priority modes will be explained later in "Printing Speed ​​Switching Control".

[0061] Here, the high-speed conveying speed is set to 600 mm / s and the low-speed conveying speed to 400 mm / s, but other speeds may be used. Furthermore, there may be three or more conveying speeds.

[0062] <Print speed switching control> Figure 7 is a flowchart representing the image forming process job in this embodiment. This flowchart shows the process of acquiring print schedule information for multiple pages in advance of the print job and setting the transport speed of the recording material based on that information so that the time until printing is completed, including the temperature switching and transport time of the fuser 311, is shortened.

[0063] This process begins when the printing device 107 receives a print job start instruction from the operation unit 224 or the client PC 103.

[0064] S040 When CPU222 receives a print job start command, it determines whether to execute it in the second mode. The first mode is one in which information about multiple pages of recording material is not acquired before the print job is executed. The second mode is one in which information about multiple pages of recording material is acquired before the print job is executed.

[0065] S050 CPU222 determines which print mode to execute the print job in. If the user selects Productivity Priority 1 in the settings screen shown in Figure 5(c), the second mode will be executed. If the user selects Productivity Priority 2 and Image Quality Priority in the settings screen shown in Figure 5(c), the first mode will be executed.

[0066] S060 If it is determined in S050 that the second mode will be executed, the number of pages M of the recording material information acquired by the acquisition unit 261 is set to 100 before the print job starts. In this embodiment, the recording material information acquired by the acquisition unit 261 is the basis weight information of the recording material.

[0067] S070 If S050 determines that the first mode will be executed, set M to 1.

[0068] S101 When CPU222 receives a print job start command, it performs the process of acquiring information about the recording material. Specifically, it acquires print information for the M pages to be printed. The process of acquiring information about the recording material to be printed will be described later using Figure 8.

[0069] S102 Next, the control unit 262 controls the transport speed of the first page based on the transport speed setting for the first page. The "transport speed setting for the first page" will be described later using Figure 9.

[0070] S103 After setting the transport speed, CPU222 starts printing the first page based on the transport speed setting for the first page.

[0071] S104 Let the number of sheets of paper to be fed, N, be 1.

[0072] S105 Next, CPU222 determines whether the last page flag is ON or OFF.

[0073] S106 If it is not ON, printing will continue, and the data for page N+M will be retrieved while the print job is running.

[0074] S107 CPU222 determines whether the retrieved page information is the final page of the job.

[0075] S108 If the retrieved page information is the last page of the job, the last page flag is turned ON, and N+M is assigned to the last page number L.

[0076] If the flag indicating the last page has been received is not ON in S105, or if it is not the last page in S107, proceed to S109.

[0077] S109 Next, it is determined whether there are any pages remaining to print, that is, whether N is equal to L, which is the last page. If N is the last page, CPU222 waits for the last page to finish printing and then terminates the print job.

[0078] S110 If N is not the last page, the transport speed determination process during printing is performed to determine the transport speed for page N+1. The transport speed determination process will be described later in "Printing Speed ​​Determination Process" using Figure 10.

[0079] S111 After determining the transport speed, CPU222 decides whether or not to switch speeds.

[0080] C112 If it is determined in S111 to perform a speed change, the speed change process is executed. When a speed change is performed, it is done when the information for page N+1 is obtained. However, it is not limited to this; the speed change may also be performed when printing page N+1.

[0081] S113 If CPU222 determines in S111 that no speed change is necessary, it feeds page N+1 at the same speed as the previous page, page N. After performing the speed change process in S112, it feeds page N+1. If necessary, it may also perform a fuser temperature change at the same time.

[0082] S114 Set the number of paper sheets N to N+1 and return to S105.

[0083] Using Figure 12, a conceptual diagram of printed page information, we will specifically explain the relationship between the page from which information is acquired, the pages that have been fed, and the pages used for determination. When the first mode is executed, if the fourth page of recording material has not yet been fed, the information for page 103 is acquired. If up to page N=3 has been fed, in order to determine the speed of page N+1=4, the print information for page N+M=103 is acquired. Then, the speed is determined using the information from page 4 to page 103, which is M=100.

[0084] As described above, according to this embodiment, the second mode can reduce the number of times the transport speed is switched compared to the first mode. This makes it possible to shorten the time until printing is completed.

[0085] In this embodiment, two speeds, 400 mm / s (first speed) and 600 mm / s (second speed), are switched between based on the printing information for a given recording material. However, the speed may be changed as needed, and there may be three or more speeds.

[0086] Furthermore, in this embodiment, the fixing temperature is fixed to a single value in "productivity priority mode 1" and "productivity priority mode 2," but it may be selectable within a predetermined temperature range. Additionally, the system may be configured to acquire information through print schedule information and select the optimal temperature setting.

[0087] In this embodiment, print schedule information for 100 pages is acquired and used for the determination, but it is not limited to this. A different value, such as 120 pages, may be used, or it may be configured to be arbitrarily changeable. For example, it may be possible to set it according to the print job that the user wants to perform using a settings screen like the one shown in Figure 11. Alternatively, the control may use data for a different number of pages depending on the conditions, such as using the number of pages that have been acquired so far for the determination.

[0088] Furthermore, in this embodiment, the transport speed is determined using the basis weight from the print schedule information, but the transport speed may also be determined using information on the size and type of recording material.

[0089] For the transport speed determination process, the speed determination can be performed by calculating which speed will complete printing faster. For example, the system assumes that printing 100 sheets at 400 mm / s is faster than switching between 600 mm / s and 400 mm / s. However, if the determination is made by calculation, one method is to calculate the switching time at the time of determination and then determine the speed. If it is determined that switching speeds will complete printing faster, then printing will be performed while switching speeds.

[0090] <Print schedule information acquisition process> Figure 8 is a flowchart showing how the CPU 222 acquires print schedule information (such as the basis weight of the printing material) for 100 pages from the external controller 102, and how the acquisition unit 261 acquires this information.

[0091] S1001 CPU222 turns OFF the flag indicating that the last page has been received and clears the last page L to 0.

[0092] S1002 Next, the acquisition unit 261 acquires a page information command for one page from the external controller 102. This page information command includes information such as the type of printing material, basis weight, size, and whether or not it is the last page of the job.

[0093] S1003 The CPU 222 stores the page information command acquired by the acquisition unit 261 in memory 223.

[0094] S1004 Add 1 to the final page number L.

[0095] S1005 CPU222 determines whether the page information saved by S1003 is the last page of the job.

[0096] S1006 If S1005 is not the last page, the system determines whether the acquisition of M pages of information has been completed, i.e., whether L and M are equal. If the reception of M pages has not been completed, the system returns to 1002; if the reception is complete, the subroutine terminates.

[0097] S1007 Regardless of whether the M page has been received in advance, the final page flag is turned ON and the subroutine's processing is terminated.

[0098] Through the above flow, CPU222 can obtain print schedule information for M pages, or L pages if the entire job is less than M pages.

[0099] <Processing to determine transport speed on page 1> The method for determining the transport speed on page 1 in this embodiment will be explained using Figure 9.

[0100] S2001 The CPU222 first calculates the number of pages K to determine the transport speed. K is M pages, or L pages if the entire job is less than M pages. More specifically, it is 1 in the first mode, and 100 or L, which is the total number of pages in the job, in the second mode.

[0101] S2002 Using the print information for K pages obtained in the aforementioned print schedule information acquisition process, the CPU 222 determines whether the recording material that can be printed at high speed consists of a predetermined number of consecutive pages.

[0102] S2003 If the control unit 262 determines that K pages can be printed at 600 mm / s, it sets the transport speed to 600 mm / s.

[0103] S2004 If, in S2002, there is recording material with a second basis weight (greater than 400 gsm) in page K, the process proceeds to S2004. If the first and second basis weights are mixed in page K, it is necessary to print at the second speed for recording material with the first basis weight and at the first speed for recording material with the second basis weight. Switching the transport speed each time the basis weight changes would increase the frequency of switching, potentially reducing the number of printed sheets per unit time. Therefore, the transport speed is set to a low speed (400 mm / s in this embodiment) to reduce the frequency of transport speed switching. This is expected to increase productivity. Thus, printing is started at the low transport speed of 400 mm / s.

[0104] Based on the information acquired by the acquisition unit 261, the control unit 262 sets the transport speed, allowing the CPU 222 to determine the speed of the first sheet.

[0105] Here, it is stated that switching the transport speed within K pages in the first mode results in faster printing time, but the required number of pages will vary depending on the configuration of the image forming apparatus 101, so it is not limited to K pages. Also, the speed is not limited to two speeds, 600 mm / s and 400 mm / s, but may have other speeds or three or more speeds.

[0106] <Processing to determine transport speed during printing> Figure 10 is a flowchart showing the process (S106) for determining the transport speed of the N+1th page during the printing operation.

[0107] S3001 CPU222 determines whether the current transport speed is operating at the high speed of 600 mm / s.

[0108] S3002 During high-speed transport at 600 mm / s, CPU222 checks whether the next printed material is 400 gsm or less.

[0109] S3003 If the next printed recording material is 400gsm or less (YES in S3002), the transport speed of the next recording material is also determined to be the high speed of 600mm / s. Specifically, this applies when the next printed recording material is 400gsm, for example.

[0110] S3004 If the next printed recording material is not 400 gsm or less (NO in S3002), the transport speed of the next recording material is determined to be a low speed of 400 mm / s. Specifically, this applies when the next printed recording material is 450 gsm.

[0111] S3005 If high-speed transport at 600 mm / s is not currently in progress, i.e., if low-speed transport at 400 mm / s is currently in progress, check whether K sheets of recording material with a thickness of 400 gsm or less follow each other.

[0112] S3006 If K sheets of paper with a thickness of 400gsm or less follow each other (YES in S305), the transport speed of the next recording material is determined to be the high speed of 600mm / s. Specifically, this applies to cases such as when 100 sheets of 300gsm recording material follow each other.

[0113] S3007 If there are no more than 100 sheets of paper with a thickness of 400gsm or less (NO in S3005), the transport speed of the next recording material will also be determined to be a low speed of 400mm / s. Specifically, this applies when there is 450gsm recording material mixed in with K sheets of printed material, or when the remaining number of printed pages is less than K sheets.

[0114] Through the above process, CPU222 can determine the speed of the next paper to be fed during printing.

[0115] The advantages of the second mode of this embodiment will now be explained. Before printing, the acquisition unit 261 acquires information on a predetermined number of recording materials. Based on this information, the control unit 262 controls the transport speed. If this information includes recording materials with a first basis weight and a second basis weight, the control unit 262 sets the transport speed to the first speed. As a result, the recording materials with the first basis weight and the recording materials with the second basis weight are transported at the first speed. Compared to the first mode, where the recording materials with the first basis weight are transported at the second speed and the recording materials with the second basis weight are transported at the first speed, the frequency of speed switching is suppressed. Downtime caused by speed switching can be reduced. As a result, productivity can be improved in mixed jobs.

[0116] In this embodiment, the time required to switch the transport speed is approximately 30 seconds. For example, suppose the first recording material is a recording material of the second basis weight, and the recording materials acquired by the acquisition unit 262 up to a predetermined number of times are recording materials of the first basis weight. Even in this case, fixing is performed at the first speed. In this embodiment, the speed switching time is long. Therefore, it is more productive to perform fixing at the first speed than to spend time switching speeds.

[0117] When the second mode is executed, the recording material of the first basis weight can be transported at either the first or second speed, depending on the job. The fixing temperature in this case is explained below. As shown in Figure 6, the fixing temperature when the recording material of the first basis weight is transported at the first speed is lower than when it is transported at the second speed. This is set taking into account the time the recording material stays in the nip section N. The longer the nip stay time, the more heat is supplied to the recording material, and therefore the lower the fixing temperature can be.

[0118] When a mixed job is executed in the second mode and recording material is transported at the second speed, the transported recording material is of the first basis weight. If the acquisition unit 261 finds that recording material of the second basis weight exists in the recording material information it acquires, it switches back to the first speed. The timing of the speed switch is when the transported recording material switches from recording material of the first basis weight to recording material of the second basis weight. Compared to switching the speed when the acquisition unit 261 finds that recording material of the second basis weight exists in the recording material information it acquires, the number of recording materials transported at the second speed increases. As a result, productivity increases due to the larger number of recording materials transported at the second speed. Therefore, in the second mode of this embodiment, while transporting recording material at the first speed, the transport speed is changed from the first speed to the second speed at the timing when the transported recording material switches to recording material of the second basis weight.

[0119] Up to this point, the explanation has assumed that the recording material is of the same type and of high quality. However, if the recording material is coated paper, for example, the amount of heat required for fixing is greater than that for uncoated paper. Therefore, while the threshold for the first and second basis weights was 400 gsm for uncoated paper, the threshold for coated paper is lower than 400 gsm, for example, 300 gsm.

[0120] <Example 2> In this embodiment, we will describe an embodiment in which the determination is made by taking into account not only the switching of the transport speed but also the switching of the fixing temperature, in addition to the switching of the transport speed compared to Embodiment 1. Note that the parts with the same configuration as Embodiment 1 will not be explained.

[0121] In this embodiment, the print image forming apparatus 101 performs image forming operations according to the relationship between basis weight, transport speed, and fixing temperature shown in Figure 13.

[0122] <Processing to determine transport speed on page 1> The method for determining the transport speed on the first page in this embodiment will be explained using the flowchart in Figure 14.

[0123] S4001 The CPU222 first calculates the number of pages K to determine the transport speed. The value of K is M, or L if the number of pages in the job is less than M. More specifically, it is 1 when the first mode is set, and 100 or L, which is the total number of pages in the job, when the second mode is set.

[0124] S4002 Using the print information for K pages obtained in the aforementioned print schedule information acquisition process, CPU 222 determines whether or not K pages of recording material with a basis weight of 400 gsm or less, which can be printed at high speed, are continuous.

[0125] S4003 If it is determined that recording material with a basis weight of 400 gsm or less is continuous for K pages (YES in S4002), then it is determined whether recording material with a basis weight of 50 to 200 gsm is continuous for K pages in order to confirm whether printing is possible at a fixing temperature of 200°C only.

[0126] S4004 If recording material with a basis weight of 50-200 gsm is used for K consecutive pages (YES in S4003), the transport speed is determined to be 600 mm / s and the fixing temperature 200°C, and the process is terminated.

[0127] S4005 If S4003 determines that recording material with a basis weight of 50-200 gsm is not K-page continuous (S4003 NO), then it is determined whether recording material with a basis weight of 201-400 gsm is K-page continuous in order to confirm whether printing is possible with only a fixing temperature of 220°C.

[0128] S4006 If recording material with a basis weight of 201-400 gsm is used for K consecutive pages (YES in S4005), the transport speed is determined to be 600 mm / s and the fixing temperature 220°C, and the process is terminated.

[0129] S4007 In S4002, if CPU222 determines that recording material with a basis weight of 50-200 gsm does not make K consecutive pages (S4002 NO), the process proceeds to S4007. Alternatively, in S4005, if CPU222 determines that recording material with a basis weight of 201-400 gsm does not make K consecutive pages (S4003 NO), the process proceeds to S4007. In S4007, CPU222 determines whether recording material with a basis weight of 101-400 gsm makes K consecutive pages in order to confirm whether printing is possible with only a fixing temperature of 160°C.

[0130] S4008 If recording material with a basis weight of 101 to 400 gsm is used for K consecutive pages (YES in S4007), the transport speed is determined to be 400 mm / s and the fixing temperature 160°C, and the process is terminated.

[0131] S4009 In S4007, if CPU222 determines that recording material with a basis weight of 101-400 gsm does not have K pages of continuous data (NO in S4007), then at least one change in fixing temperature or transport speed is required. Therefore, the transport speed and fixing temperature that minimize the sum of the recording material transport time, fixing temperature change time, and transport speed change time are determined.

[0132] Based on the above flow, CPU222 can determine the transport speed and fixing temperature for the first page. During printing, the transport speed and fixing temperature will continue to be determined for the first page as long as possible, and a switch will be implemented when a recording material that cannot be printed without a switch is encountered.

[0133] As described above, according to this embodiment, in a print job that requires switching between transport speed and fixing temperature, the switching time can be reduced by obtaining information on multiple pages of print paper before printing and selecting the appropriate transport speed and fixing temperature. This makes it possible to shorten the time until printing is completed.

[0134] Furthermore, if the image forming apparatus 101 interrupts image forming for any reason (for example, when a jam occurs) and then resumes image forming, the acquisition unit 261 performs a transport speed determination process for the first page. This allows image forming after the interruption to be performed without depending on the information of the recording material before the interruption. For example, if the transport speed before the interruption was low, and the basis weight of the recording material to be processed after the interruption is only the first basis weight, the transport speed can be set to the second speed after the interruption. This improves productivity after the interruption. [Explanation of Symbols]

[0135] 101 Image forming apparatus 102 External Controller 222 CPU 261 Acquisition Department 262 Control Unit 311 Fixing device 401 Fixing belt 402 Pressure Roller 403 Pad 404 Heating roller

Claims

1. A heating rotating body that applies heat to the recording material, A pressurizing rotating body that pressurizes the aforementioned heating rotating body, The heating rotating body and the pressurizing rotating body apply heat and pressure to the recording material, fixing the toner image to the recording material. A control unit that controls the transport speed of the recording material, It includes an acquisition unit that acquires information regarding the basis weight of the recording material, The control unit, A mixed job for forming toner images on a plurality of recording materials, including a recording material with a first basis weight and a recording material with a second basis weight greater than the first basis weight, wherein when executing a mixed job in which the basis weight of the first recording material is the first basis weight and the basis weight of the second recording material is the second basis weight, a first mode is provided in which the transport speed for transporting the first recording material of the mixed job is set to a first predetermined speed based on the basis weight information of the first recording material of the mixed job and the basis weight information of the second recording material of the mixed job, and the transport speed for transporting the second recording material of the mixed job is set to the first predetermined speed based on the basis weight information of the first recording material of the mixed job and the basis weight information of the second recording material of the mixed job. Image forming apparatus for forming toner images on a plurality of recording materials, including a recording material with a first basis weight and a recording material with a second basis weight greater than the first basis weight, wherein when performing a mixed job in which the basis weight of the first recording material is the first basis weight and the basis weight of the second recording material is the second basis weight, the apparatus is characterized in that it can selectively execute one mode from a plurality of modes, including a second mode in which, based on the basis weight information of the first recording material of the mixed job and not on the basis weight information of the second recording material of the mixed job, the transport speed of the first recording material of the mixed job is set to a second predetermined speed greater than the first predetermined speed, and based on the basis weight information of the second recording material of the mixed job and not on the basis weight information of the first recording material of the mixed job, the transport speed of the second recording material of the mixed job is set to the first predetermined speed, and the transport speed of the second recording material of the mixed job is set to the first predetermined speed, based on the basis weight information of the second recording material of the mixed job.

2. When the first mode is executed, the acquisition unit acquires the information of a predetermined number of recording materials before the first recording material of the mixed job is transported to the nip section where the recording material is nipped by the heating rotating body and the pressurizing rotating body. The image forming apparatus according to feature 1.

3. Before the first recording material of the mixed job is transported to the nip section, the number of recording materials of the information acquired by the acquisition unit is greater when the first mode is executed than when the second mode is executed. The image forming apparatus according to feature 2.

4. When the second mode is executed, the number of recording materials for which the acquisition unit acquires the information before the first recording material of the mixed job is transported to the nip section is one. The image forming apparatus according to feature 3.

5. When the first mode is executed, the number of recording materials for which the acquisition unit acquires the information is multiple, before the first recording material of the mixed job is transported to the nip section. The image forming apparatus according to feature 3.

6. When the first mode is executed, the number of recording materials for which the information is acquired by the acquisition unit is 10 or more before the first recording material of the mixed job is transported to the nip section. The image forming apparatus according to feature 5.

7. When executing the mixed jobs exceeding the predetermined number in the first mode, the acquisition unit updates the information during the mixed jobs. The image forming apparatus according to feature 2.

8. If the mixed job is executed in the first mode, and the mixed job is interrupted and then resumed, the acquisition unit acquires the information of the predetermined number of recording materials that will be transported after the resumed operation, and the control unit sets the transport speed of the recording materials based on the information acquired by the acquisition unit. The image forming apparatus according to feature 2.

9. The image forming apparatus according to claim 1, characterized in that, when executing the first mode, the control unit is configured to determine the transport speed of the nth recording material of the mixed job based on basis weight information of a predetermined number of recording materials starting from the nth recording material of the mixed job when performing a fixing operation to fix a toner image to the nth recording material of the mixed job.

10. When the control unit executes the first mode, (i) When the transport speed of the nth recording material is the first predetermined speed, if a predetermined number of recording materials with the basis weight of the first recording material follow the nth recording material, the transport speed of the (n+1)th recording material is set to the second predetermined speed. (ii) When the transport speed of the nth recording material is the first predetermined speed, and the basis weight of the (n+1)th recording material is the second basis weight, the image forming apparatus according to claim 9, characterized in that the transport speed of the (n+1)th recording material is set to the first predetermined speed.

11. The image forming apparatus according to claim 9, characterized in that, when executing the first mode, the control unit is configured to determine the transport speed of the nth recording material of the mixed job based on whether or not a predetermined number of recording materials with a basis weight of first predetermined basis weight or less follow the nth recording material of the mixed job.

12. When the control unit executes the first mode, in determining the transport speed of the nth recording material of the mixed job, if a predetermined number of recording materials with a basis weight of less than or equal to a first predetermined basis weight follow the nth recording material of the mixed job, The image forming apparatus according to claim 11, characterized in that, if a predetermined number of recording materials have a basis weight range within a first basis weight range, the transport speed of the nth recording material in the mixed job is set to the second predetermined speed and the fixing temperature is set to the first temperature.

13. When the control unit executes the first mode, in determining the transport speed of the nth recording material of the mixed job, if a predetermined number of recording materials with a basis weight of less than or equal to a first predetermined basis weight follow the nth recording material of the mixed job, and if the predetermined number of recording materials with a basis weight range within the first basis weight range do not follow, but rather the predetermined number of recording materials with a basis weight range within the second basis weight range follow, the transport speed of the nth recording material of the mixed job is set to the second predetermined speed, the fixing temperature is set to a second temperature higher than the first temperature, and the lower limit of the second basis weight range is greater than the upper limit of the first basis weight range, characterized in that the image forming apparatus according to 12.

14. When the control unit executes the first mode, in determining the transport speed of the nth recording material of the mixed job, if a predetermined number of recording materials with a basis weight of first predetermined basis weight or less follow the nth recording material of the mixed job, and if a predetermined number of recording materials with a basis weight range within the first basis weight range do not follow, and a predetermined number of recording materials with a basis weight range within the second basis weight range do not follow, and a predetermined number of recording materials with a basis weight range wider than the second basis weight range follow, the transport speed of the nth recording material of the mixed job is set to the first predetermined speed, and the fixing temperature is set to a third temperature lower than the first temperature, as described in 13.

Images