Image forming apparatus

Abstract

To notify a user of the possibility of deterioration in the image quality of a toner image when a mixed job in which recording materials having different fixing temperatures are mixed is executed by using a common temperature.SOLUTION: When a mixed productivity priority mode for executing mixed jobs by using a common temperature is input (Yes in S401), a CPU executes "application determination processing" of the mixed productivity priority mode (S402). The "application determination processing" determines that the mixed productivity priority mode is applicable when both the in-machine temperature and the in-machine humidity detected by the temperature and humidity sensor are within a predetermined range, and determines that the mixed productivity priority mode is not applicable when at least one of the in-machine temperature and the in-machine humidity is not within the predetermined range. After the execution of the "application determination processing", when the circumstances do not allow the application of the mixed productivity priority mode (No in S403), the CPU displays a "notification screen" on the display in order to notify the user that the circumstances deviate from the circumstances allowing the operation in the mixed productivity priority mode (S406).SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a copier, printer, facsimile, or a multifunction machine having multiple functions of these. [Background technology]

[0002] The image forming apparatus is equipped with a fixing device that fixes a toner image formed on a recording material by applying heat and pressure to the recording material while nipping and conveying the recording material. The fixing device has a heating rotor for heating the recording material and a pressure rotor that pressurizes the heating rotor to form a fixing nip where heat and pressure are applied while nipping and conveying the recording material. Because the amount of heat required to fix a toner image differs depending on the basis weight of the recording material, the fixing device is capable of adjusting the set temperature of the heating rotor (called the fixing temperature) depending on the basis weight of the recording material.

[0003] However, when switching the fixing temperature, the print operation of the image forming device may be temporarily stopped, and such a temporary stop reduces the productivity of the recording material. Therefore, when executing a continuous image forming job (called a mixed job) in which toner images are continuously formed on a plurality of recording materials that are a mixture of recording materials with different fixing temperatures, it has been proposed to reduce the number of temporary stops and suppress the reduction in productivity of the recording material by using a common temperature for those recording materials before starting the mixed job (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-321478 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventionally, when mixed jobs are executed using a common temperature, the image quality of the toner image fixed on the recording material may be deteriorated.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an image forming device that can notify the user without executing a mixed job if there is a risk of deterioration in the image quality of the toner image when a mixed job in which recording materials with different fixing temperatures are mixed is executed using a common temperature. [Means for solving the problem]

[0007] An image forming apparatus according to one embodiment of the present invention is an image forming apparatus having an image forming unit that forms a toner image on a recording material, a first rotating body, and a second rotating body that contacts the first rotating body to form a fixing nip portion that sandwiches and conveys the recording material, and that applies heat and pressure to the recording material on which the toner image has been formed to fix the toner image to the recording material, and a first mode in which a fixing temperature that is a set temperature of the first rotating body is set to a first temperature when the basis weight of the recording material is a first basis weight, and is set to a second temperature that is lower than the first temperature when the basis weight is a second basis weight that is smaller than the first basis weight, and a second mode in which a common temperature is set regardless of the basis weight of the recording material. the second mode being set to a predetermined value, an input unit capable of inputting either the first mode or the second mode; a detection unit for detecting an in-machine temperature and an in-machine humidity within the image forming apparatus; and a display unit for displaying a message that the second mode cannot be applied to the continuous image forming job if the in-machine temperature and the in-machine humidity detected by the detection unit are not both within a predetermined range when the second mode is input to the input unit. [Effects of the Invention]

[0008] According to the present invention, when a continuous image forming job that mixes recording materials with different fixing temperatures depending on the basis weight is executed in the second mode that uses a common temperature, if there is a risk of the image quality of the toner image deteriorating, the user can be notified by displaying that the second mode cannot be applied. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an image forming system. [Figure 2] FIG. 1 is a block diagram showing a system configuration. [Figure 3] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention. [Figure 4] FIG. [Figure 5] 10 is a temperature table showing fixing temperatures according to the basis weight of the recording material, in which (a) high-speed balanced temperature control mode, (b) low-speed balanced temperature control mode, and (c) image quality priority temperature control mode. [Figure 6] (a) is a diagram showing an initial screen, (b) is a diagram showing an application mode selection screen, and (c) is a diagram showing a setting screen for speed / image quality priority adjustment. [Figure 7] 10A and 10B are diagrams for explaining the mixed load productivity priority mode, in which (a) shows a case where the print order condition is satisfied, and (b) shows a conventional example. [Figure 8] 10 is a flowchart showing a standby process. [Figure 9] 10 is a flowchart showing application determination processing. [Figure 10] FIG. 10 is a diagram showing a notification screen displayed during standby. [Figure 11] 10 is a flowchart showing a job start process according to the first embodiment. [Figure 12] 1A is a diagram showing an operation setting screen, and FIG. 1B is a diagram showing a notification screen displayed at the start of a job according to the first embodiment. [Figure 13] 10 is a flowchart showing processing during job execution according to the first embodiment. [Figure 14] 10 is a flowchart showing a job start process according to a second embodiment. [Figure 15] FIG. 10 is a diagram showing a forced application selection screen displayed when a job starts. [Figure 16] 10 is a flowchart showing a part of a process during job execution according to the second embodiment. [Figure 17] 10 is a flowchart showing a part of a process during job execution according to the second embodiment. [Figure 18]FIG. 10 is a diagram showing a forced application selection screen displayed during job execution. DETAILED DESCRIPTION OF THE INVENTION

[0010] [First embodiment] <Image forming system> 1 is a configuration diagram of an image processing system including an image forming apparatus 101 of this embodiment. The image processing system includes the image forming apparatus 101 and an external controller 102. The image forming apparatus 101 is, for example, a multifunction peripheral (MFP), a multifunction peripheral (MFP), etc. The external controller 102 is, for example, an image processing controller, a digital front end (DFE), a print server, etc.

[0011] The image forming apparatus 101 and the external controller 102 are communicatively 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 (image forming job) from the client PC 103.

[0012] A printer driver having a function of converting image data into a print description language that can be processed by the external controller 102 is installed in the client PC 103. A user can instruct printing via the printer driver using various applications. The printer driver transmits image data to the external controller 102 based on an image formation job. The external controller 102 accepts an image formation job including 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.

[0013] The image forming apparatus 101 is configured by connecting devices with multiple 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 the printing device 107 and a finisher 109. The printing device 107 forms an image on a recording material fed from a paper feed unit provided at the bottom of the main body using a developer (e.g., toner). The printing device 107 forms images in yellow (Y), magenta (M), cyan (C), and black (K). A full-color image in which images of each color are superimposed is formed on the recording material. The recording material on which the image has been formed is transported from the printing device 107 to the finisher 109. The finisher 109 stacks the recording material on which the image has been formed.

[0014] Although this image processing system is configured such that an external controller 102 is connected to an image forming apparatus 101, the external controller 102 is not necessarily required. For example, the image forming apparatus 101 may be configured to directly receive an image forming job including image data from a client PC 103 via an external LAN 104. In this case, the image forming apparatus 101 performs the data analysis and rasterization processes that are performed by the external controller 102. In other words, the image forming apparatus 101 and the external controller 102 may be configured as an integrated unit.

[0015] <System configuration> 2 is a diagram showing the system configuration for controlling the operation 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 will be described.

[0016] <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 communicating with other devices. The printing device 107 includes a CPU (Central Processing Unit) 222, a memory 223, 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 image creating unit 228, a fixing device 311, and a paper feed unit 230 for forming an image. The printing device 107 includes an operation unit 224 and a display 225 (e.g., a touch panel) as a user interface. The printing device 107 includes a timer 251 and a temperature and humidity sensor 252 for adjusting correction values ​​for optimally correcting the geometric characteristics of the images on the front and back sides. Here, the geometric characteristics of the image include, for example, squareness and the printing position of the image on the recording material. These components are connected to each other via a system bus 233 so that they can communicate with each other.

[0017] The communication I / F 217 is connected to the finisher 109 via a communication cable 249 and controls communication with the finisher 109. When the printing device 107 and the finisher 109 operate in cooperation with each other, information and data are sent and received via the communication I / F 217. The LAN I / F 218 is connected to the external controller 102 via the internal LAN 105 and controls communication with the external controller 102. The printing device 107 receives print settings from the external controller 102 via the LAN I / F 218. The video I / F 220 is connected to the external controller 102 via the video cable 106 and controls communication with the external controller 102. The printing device 107 receives image data representing an image to be formed from the external controller 102 via the video I / F 220.

[0018] The CPU 222 as an execution unit comprehensively controls image processing and printing by executing computer programs stored in the memory 223. The memory 223 provides a work area when the CPU 222 executes various processes. When performing image formation processing, the CPU 222 can control the exposure unit 227, the image forming unit 228, the fixing device 311, and the paper feed unit 230.

[0019] The exposure unit 227 includes a photoconductor, a charging wire that charges the photoconductor, and a light source that exposes the photoconductor charged by the charging wire to light to form an electrostatic latent image on the photoconductor. The photoconductor may be, 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. A charging roller may also be used instead of the charging wire. The exposure unit 227 charges the surface of the photoconductor to a uniform negative potential using the charging wire. The exposure unit 227 outputs a laser beam from the light source based on image data. The laser beam scans the uniformly charged surface of the photoconductor. This changes the potential of the photoconductor at the position irradiated by the laser beam, forming an electrostatic latent image on the surface. Four photoconductors are provided, one for each of the four colors: yellow (Y), magenta (M), cyan (C), and black (K). Electrostatic latent images corresponding to different color images are formed on the four photoconductors.

[0020] The image forming unit 228, which serves as an image forming unit, transfers the toner image formed on the photosensitive member onto a recording material. The image forming unit 228 includes a developing unit, a transfer unit, and a toner supply unit. The developing unit forms a toner image by attaching negatively charged toner from a developing cylinder to an electrostatic latent image formed on the surface of the photosensitive member. Four developing units are provided, one for each of the four colors: yellow (Y), magenta (M), cyan (C), and black (K). The developing units visualize the electrostatic latent image on the photosensitive member using toner of the corresponding color.

[0021] The transfer unit has an intermediate transfer belt 308 and transfers toner images from the photosensitive members to the intermediate transfer belt 308. Primary transfer rollers are provided at positions facing the photosensitive members across the intermediate transfer belt 308. When a positive potential is applied to the primary transfer rollers, the toner images from each of the four photosensitive members are transferred onto the intermediate transfer belt in a superimposed state. As a result, a full-color toner image is formed on the intermediate transfer belt. The toner image formed on the intermediate transfer belt is transferred to a recording material by a secondary transfer roller, which will be described later. When a positive potential is applied to the secondary transfer rollers, the full-color toner image is transferred from the intermediate transfer belt 308 to the recording material.

[0022] The fixing device 311, which serves as a fixing unit, 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 melts and fixes the toner image on the recording material by heating and pressurizing the toner image on the recording material with the heater and the pair of rollers. This produces a product in which an image is formed on the recording material. The paper feed unit 230 has a conveying roller and various sensors on the conveying path, and controls the feeding operation of the recording material.

[0023] The operation unit 224 as an input unit is an input device that accepts various setting inputs and operation instructions from the user, and is, for example, various input keys or a touch panel. The display 225 as a display unit is an output device that displays setting information of the image forming apparatus 101 and the processing status (status information) of an image formation job. In this embodiment, the operation unit 224 is capable of inputting, for example, an instruction to start a mixed job and an operation mode. A mixed job is a continuous image formation job in which images are formed on multiple sheets of recording material with different basis weights, and a first recording material with a first basis weight is mixed with a second recording material with a second basis weight smaller than the first basis weight.

[0024] The timer 251 counts the time. The CPU 222 acquires the current date and time from the count value of the timer 251. The temperature and humidity sensor 252 as a detection unit detects the temperature and humidity inside the image forming apparatus 101 (inside the image forming apparatus, more specifically, inside the printing apparatus 107). The CPU 222 acquires the temperature and humidity inside the apparatus as environmental conditions based on the detection results of the temperature and humidity sensor 252. The temperature setting unit 263 sets the fixing temperature according to the basis weight of the recording material. The CPU 202 can change the temperature of the fixing belt 401 of the fixing device 311 based on the fixing temperature set by the temperature setting unit 263.

[0025] <Finisher> The finisher 109, for example, staples a product output from the printing device 107. The finisher 109 includes a communication I / F 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 each other. The communication I / F 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 operate in cooperation with each other, information and data are sent and received via the communication I / F 241. The CPU 242 executes a control program stored in the memory 243 and performs various controls required for paper discharge. The memory 243 stores the control program. The memory 243 also provides a work area for the CPU 242 when executing various processes. The paper discharge control unit 244 discharges the conveyed recording material based on instructions from the CPU 242.

[0026] <External controller> The external controller 102 includes a LAN I / F 213, a LAN I / F 214, and a video I / F 215 for communicating with other devices. The external controller 102 includes a CPU 208 and a memory 209 for controlling the operation of the external controller 102. The external controller 102 includes a keyboard 211 and a display 212 as user interfaces. These components are connected to each other via a system bus 216 so that they can communicate with each other.

[0027] The 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 acquires an image formation job from the client PC 103 via the LAN I / F 213. The LAN I / F 214 is connected to the printing device 107 via the internal LAN 105 and controls communication with the printing device 107. The external controller 102 transmits print settings to the printing device 107 via the LAN I / F 214. The video I / F 215 is connected to the printing device 107 via the video cable 106 and controls communication with the printing device 107. The external controller 102 transmits image data to the printing device 107 via the video I / F 215.

[0028] The CPU 208 executes computer programs stored in the memory 209 to comprehensively perform processes such as receiving image data transmitted from the client PC 103, RIP processing, and transmitting image data to the image forming apparatus 101. 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 setting inputs and operation instructions from the user. The display 212 is an output device that displays information about applications executed by the external controller 102 using still images and moving images.

[0029] <Client PC> The client PC 103 includes a CPU 201, a memory 202, a keyboard 204, a display 205, and a LAN I / F 206. These components are connected via a system bus 207 so that they can communicate with each other.

[0030] The CPU 201 controls the operation of the client PC 103 by executing computer programs stored in the memory 202. In this embodiment, the CPU 201 creates image data and transmits an image formation job. The memory 202 provides a work area for the CPU 201 to execute various processes. The keyboard 204 and the display 205 are user interfaces. The keyboard 204 is an input device that accepts instructions from a user. The display 205 is an output device that displays information about applications executed by the client PC 103 as still images or moving images. 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 transmits an image formation job including image data to the external controller 102 via the LAN I / F 206.

[0031] The external controller 102 and the image forming apparatus 101 are connected via an internal LAN 105 and a video cable 106, but any other configuration is acceptable as long as they are capable of transmitting and receiving data necessary for printing, and for example, they may be connected via only the video cable 106. The memory 202, memory 209, memory 223, and memory 243 may each be a storage device for holding data and programs. These memories may be, for example, volatile random access memory (RAM), non-volatile read only memory (ROM), storage, or universal serial bus (USB) memory.

[0032] <Configuration of image forming device> 3 is a configuration diagram of the image forming apparatus 101. An operation unit 224 having a display 225 is provided on the top of the printing device 107. The display 225 displays information on the printing status and settings of the image forming apparatus 101. The recording material (result) on which an image has been formed by the printing device 107 is conveyed to a finisher 109 provided at a subsequent stage.

[0033] The printing device 107 includes a paper feed unit 230 including a plurality of paper feed decks 301, 302 and a conveyance path 303. Each of the paper feed decks 301, 302 can accommodate a different type of recording material. Information about the accommodated recording material (basis weight, type of recording material, etc.) can be detected on the device side, and in this embodiment, the configuration allows the user to set this information via the operation unit 224.

[0034] The top sheet of recording material stored in each paper feed deck 301, 302 is separated and fed to a conveying path 303. The printing device 107 includes image forming units 304, 305, 306, and 307 as the exposure unit 227 for forming images. The printing device 107 forms color images. 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).

[0035] The printing device 107 includes, as the image creation unit 228, an intermediate transfer belt 308 onto which toner images are transferred from the image forming units 304, 305, 306, and 307, and a secondary transfer roller 309. The intermediate transfer belt 308 rotates clockwise in the figure, and toner images are transferred and superimposed on each other from the image forming units 307, 306, 305, and 304 in this order. As a result, a full-color toner image is formed on the intermediate transfer belt 308. The intermediate transfer belt 308 conveys the toner image to the secondary transfer roller 309 as it rotates. A recording material is conveyed to the secondary transfer roller 309 in synchronization with the timing at which the toner image is conveyed to the secondary transfer roller 309. The secondary transfer roller 309 transfers the toner image on the intermediate transfer belt 308 onto the conveyed recording material.

[0036] The printing apparatus 107 includes a fixing device 311. The fixing device 311 has a fixing belt 401 and a pressure roller 402 to fix the toner image onto the recording material. Heat and pressure are applied to the recording material as it passes through a fixing nip formed by the fixing belt 401 and the pressure roller 402. This causes the toner image to melt and adhere to the first surface of the recording material.

[0037] The recording material that has passed through the fixing device 311 is guided to a conveying path 315. If double-sided printing is instructed, an image is also formed on the back side (second side). For this reason, the recording material is guided to a reversing path 316. The recording material that has been conveyed to the reversing path 316 has its conveying direction reversed and is conveyed to a double-sided conveying path 317. The recording material is reversed by switchback conveyance via the reversing path 316 and the double-sided conveying path 317. The recording material is conveyed to the conveying path 303 by the double-sided conveying path 317, and passes through a secondary transfer roller 309 and a fixing device 311, where an image is formed on the second side, which is different from the first side.

[0038] In the case of single-sided printing, or in the case of double-sided printing with images formed on both sides, the recording material is conveyed to a conveying path 315 and delivered to the finisher 109. The finisher 109 can stack recording materials delivered from the printing device 107. The finisher 109 is equipped with a conveying path 331 and a stack tray 332 on which recording materials are stacked. Conveying path 331 is provided with conveying sensors 333, 334, 335, and 336. The recording material conveyed from the printing device 107 passes through the conveying path 331 and is stacked on the stack tray 332. The conveying sensors 333, 334, 335, and 336 detect the passage of the recording material conveyed along the conveying path 331. If the leading or trailing edge of the recording material in the conveying direction is not detected by the conveying sensors 333, 334, 335, and 336 even after a predetermined time has elapsed since the start of conveyance of the recording material, the CPU 242 determines that a conveying jam (conveyance abnormality) has occurred in the finisher 109. In this case, the CPU 242 notifies the printing device 107 that a conveying jam has occurred.

[0039] <Fixing device> Next, the configuration of the fixing device in this embodiment will be described in detail with reference to FIG. 4. FIG. 4 is a cross-sectional view of the fixing device in this embodiment. In FIG. 4, the recording material is transported from right to left on the paper surface. The fixing device 311 has a heating unit 410 having a heat source and a pressure roller 402 that forms a fixing nip portion N together with the heating unit 410. The heating unit 410 has a fixing belt 401 as an endless, rotatable first rotating body, a pad member (hereinafter referred to as pad) 403, a heating roller 404, and a steering roller 405.

[0040] The heating roller 404 has a halogen heater (not shown) installed inside, capable of generating heat up to a predetermined temperature. The fixing belt 401 is heated by the heating roller 404, and the fixing temperature is controlled according to the basis weight of the recording material based on temperature detection by a thermistor (not shown). The thermistor may be configured to detect the surface temperature of the heating roller 404 or the fixing belt 401. The pressure roller 402, serving as the second rotating body, is a roller having an elastic layer formed on the outer periphery of its shaft and a release layer formed on the outer periphery of the elastic layer. Here, the pressure roller 402 is driven to rotate by a motor 407, and the fixing belt 401, which is in contact with the pressure roller 402, is rotated accordingly. When the recording material bearing an unfixed toner image is nipped and conveyed between the pressure roller 402 and the fixing belt 401 at the fixing nip N, the heat and pressure necessary for fixing are applied. The toner image is then fixed onto the recording material P. It is sufficient that the motor 407 rotates at least one of the fixing belt 401 and the pressure roller 402 .

[0041] <Relationship between basis weight and conveying speed> The image forming apparatus 101 in this embodiment is capable of conveying the recording material at a plurality of speeds, including a first speed and a second speed, as the conveying speed for conveying the recording material through the fixing nip N. In this embodiment, the first speed is a high conveying speed of "600 mm / s," and the second speed is a low conveying speed of "400 mm / s" that is slower than the first speed. Although two speeds are given as an example here, the recording material may be conveyed at three or more speeds.

[0042] The reason why the recording material is transported at multiple transport speeds in this embodiment will be explained. The greater the basis weight of the recording material, the greater the amount of heat required to fix the toner image. The faster the recording material transport speed, the shorter the time that the recording material can be heated in the fixing nip N. Therefore, if recording materials with large basis weights are continuously transported at high speed, fixability may not be guaranteed. Therefore, in order to ensure fixability of recording materials with large basis weights, it is necessary to provide a low transport speed in addition to a high transport speed.

[0043] <Temperature table> Figures 5(a) to 5(c) are temperature tables showing applicable fixing temperatures at the two types of conveying speeds mentioned above. Figure 5(a) shows the temperature table for the high-speed balanced temperature control mode (conveying speed 600 mm / s), Figure 5(b) shows the temperature table for the low-speed balanced temperature control mode (conveying speed 400 mm / s), and Figure 5(c) shows the temperature table for the image quality priority temperature control mode (conveying speed 400 mm / s). These temperature tables are stored in advance in memory 223 (see Figure 2). In each temperature table, a fixing temperature corresponding to the basis weight of the recording material is set for each type of recording material (here, fine paper and coated paper).

[0044] However, as shown in Fig. 5(a), the temperature table for the high-speed balanced temperature control mode does not set a fixing temperature according to the basis weight of the recording material that is equal to or greater than a predetermined value depending on the type of recording material. This is because, when the conveying speed is set to "600 mm / s," the halogen heater does not have the capacity to heat the fixing belt 401 to the fixing temperature required to apply the heat amount appropriate for fixing to the recording material.

[0045] The temperature setting unit 263 (see FIG. 2) can set the temperature of the fixing belt 401 to a first temperature based on a temperature table when the recording material has a first basis weight, or to a second temperature lower than the first temperature when the recording material has a second basis weight smaller than the first basis weight. The CPU 222 can change the temperature of the fixing belt 401 based on the set temperature. Note that because it takes time for the temperature of the fixing belt 310 to reach the set temperature, it is necessary to temporarily suspend the execution of the mixed job (called a printing operation) that is currently being executed, and this suspension reduces the productivity of the recording material. Furthermore, when changing the conveying speed during the execution of the mixed job, it is necessary to temporarily suspend the mixed job until the conveying speed reaches the set speed, and this suspension reduces the productivity of the recording material.

[0046] <Operation mode> Next, the operating modes executable by the fixing device 311 of this embodiment will be described with reference to Figures 6(a) to 6(d). The fixing device 311 can execute a productivity priority mode and an image quality priority mode, and the productivity priority mode is further divided into two modes: a mixed sheet productivity priority mode and a paper type-specific productivity priority mode. The user can set the operating mode according to a setting screen displayed on the display 225 by the CPU 222. The operating mode is stored in the memory 223.

[0047] Fig. 6(a) shows the initial screen. When the user selects the soft key "Advanced Mode" (a-1) from the initial screen, the CPU 222 displays the advanced mode selection screen shown in Fig. 6(b) on the display 225. When the user selects the soft key "Speed / Image Quality" (b-1) from the advanced mode selection screen, the CPU 222 displays the speed / image quality priority adjustment setting screen shown in Fig. 6(c) on the display 225.

[0048] If the user sets "Productivity Priority 1" (c-1) and clicks "OK," mixed jobs can be executed in mixed load productivity priority mode (second mode). In this embodiment, when mixed load productivity priority mode is set, either the temperature table for the "high speed balanced temperature control mode" or the temperature table for the "low speed balanced temperature control mode" is used. Which of the temperature table for the "high speed balanced temperature control mode" or the "low speed balanced temperature control mode" is used will be described later (see FIG. 7).

[0049] If the user selects "Productivity Priority 2" (c-2) and clicks "OK," mixed jobs can be run in paper type-specific productivity priority mode (first mode). When this mode is selected, the "High-Speed ​​Balanced Temperature Control Mode" temperature table shown in Figure 5(a) is used for fine paper with a basis weight of 60 gsm to 256 gsm and coated paper with a basis weight of 64 gsm to 220 gsm. The "Low-Speed ​​Balanced Temperature Control Mode" temperature table shown in Figure 5(b) is used for fine paper with a basis weight of 257 gsm to 500 gsm and coated paper with a basis weight of 221 gsm to 500 gsm. The paper type-specific productivity priority mode can achieve better toner image quality than the mixed-load productivity priority mode.

[0050] If the user selects "Image Quality Priority" (c-3) and clicks "OK," mixed jobs can be executed in image quality priority mode. Image quality priority mode prioritizes the quality of the image to be printed. Therefore, as shown in the temperature table for the image quality priority mode in Figure 5(c), the temperature can be adjusted more precisely depending on the basis weight in image quality priority mode than in productivity priority mode. In other words, the quality of the toner image formed on the recording material depends on the amount of heat applied to the toner image. The basis weight of the recording material determines the optimal temperature for fixing the toner image, and applying this optimal temperature improves the quality of the toner image. The temperature table for the image quality priority mode specifies the fixing temperature more precisely depending on the basis weight and type of recording material. Therefore, when printing mixed jobs in image quality priority mode, the temperature of the fixing belt 310 may need to be adjusted more frequently than when printing mixed jobs in productivity priority mode.

[0051] <Mixed load productivity priority mode> Next, the mixed-load productivity priority mode will be explained using Figures 7(a) to 7(c). Figure 7(a) shows the case where the print order conditions are met, and Figure 7(b) shows a conventional example. The print order conditions are, for example, that there are no "two or more" consecutive sheets of cardboard, and that there are "five or more" consecutive sheets of plain paper after the cardboard.

[0052] Note that, although the printing order conditions are exemplified here as "two or more sheets" for cardboard and "five or more sheets" for plain paper, the present invention is not limited to this. The above-mentioned "two or more sheets" and "five or more sheets" numbers of recording materials may be changeable based on the detection results detected by the temperature and humidity sensor 252. For example, if the in-machine temperature and in-machine humidity detected by the temperature and humidity sensor 252 are equal to or higher than predetermined values ​​(e.g., 20°C and 60%), the above-mentioned "two or more sheets" and "five or more sheets" may be used, whereas if the in-machine temperature and in-machine humidity are lower than the predetermined values, the above-mentioned "three or more sheets" and "eight or more sheets" may be used.

[0053] As shown in Figures 7(a) and 7(b), in the case of a mixed job in which the first sheet is 257gsm thick paper, the second to sixth sheets are 80gsm plain paper, and the seventh sheet is 257gsm thick paper, the temperature table for the high-speed balanced temperature control mode shown in Figure 5(a) does not specify a temperature setting value of 257gsm. Therefore, in the conventional example, when executing a mixed job in which 257gsm thick paper and 80gsm plain paper are mixed, as shown in Figure 7(b), it is necessary to use the temperature table for the low-speed balanced temperature control mode (Figure 5(b)).

[0054] In this embodiment, the first sheet of 257 gsm thick paper is printed at the same feed speed (600 mm / s) and fixing temperature (171°C) as for 80 gsm plain paper, and then the second through sixth sheets of 80 gsm plain paper are printed. This allows the heat lost by the first sheet to be recovered, and the seventh sheet of 257 gsm thick paper can be fixed at the same feed speed (600 mm / s) and temperature setting (171°C). Therefore, the printing operation is started using the temperature table for the high-speed balanced temperature control mode (Figure 5(a)). In this way, when the mixed productivity priority mode is input and a mixed job is acquired in which there are no more than two consecutive sheets of thick paper (a first number or more consecutive sheets) and five or more consecutive sheets of plain paper (a second number or more consecutive sheets) after the thick paper, the print job is started by setting the feed speed to the feed speed for the high-speed balanced temperature control mode (600 mm / s) and the fixing temperature to the common temperature for plain paper (171°C).

[0055] However, to execute mixed jobs using a common temperature as described above, environmental conditions must be met, such as an in-machine temperature of "21°C or higher but lower than 26°C" and an in-machine humidity of "30% or higher but lower than 60%." For example, in a low-temperature environment where the in-machine temperature is "less than 15°C," the temperature of the recording material is low, so even if heat is applied at the common temperature, the toner may not melt sufficiently, resulting in poor fixing and a deterioration in the image quality of the toner image. As such, since the fixability of the toner image to the recording material changes depending on the in-machine temperature and humidity, environmental conditions are set to ensure the fixability of the toner image when a common temperature is used.

[0056] In this embodiment, if the above environmental conditions are not met, the user is notified that the environmental conditions are not suitable for the mixed load productivity priority mode, thereby enabling the user to understand whether the mixed load productivity priority mode is applicable. The present embodiment that realizes this will be described below. To make the description easier to understand, the following cases will be described: standby, job start, and job execution. Note that standby refers to a state in which the image forming apparatus 101 is in a standby state in which it can immediately start image formation on a recording material in response to an input of an image formation job.

[0057] <Standby processing> First, the standby process will be described with reference to Fig. 2 and Fig. 8 to Fig. 10. Fig. 8 is a flowchart showing the standby process. The standby process is started by the CPU 222 when the image forming apparatus 101 is powered on.

[0058] 8, the CPU 222 refers to the operation modes stored in the memory 223 and determines whether the mixed load productivity priority mode has been input (S401). If the mixed load productivity priority mode has not been input (No in S401), the CPU 222 jumps to the process of S404. If the mixed load productivity priority mode has been input (Yes in S401), the CPU 222 executes the "application determination process" for the mixed load productivity priority mode (S402).

[0059] 9 shows the "application determination process" (S402 in FIG. 8) for the mixed load productivity priority mode. As shown in FIG. 9, the CPU 222 acquires the in-machine temperature detected by the temperature and humidity sensor 252 (S301), and determines whether the acquired in-machine temperature is within a predetermined range (e.g., 21° C. or higher and lower than 26° C.) (S302). If the in-machine temperature is within the predetermined range (Yes in S302), the CPU 222 acquires the in-machine humidity detected by the temperature and humidity sensor 252 (S303), and determines whether the acquired in-machine humidity is within a predetermined range (e.g., 30% or higher and lower than 60%) (S304). If both the in-machine temperature and the in-machine humidity are within the predetermined range (Yes in S304), the CPU 222 stores the mixed load productivity priority mode as applicable in the memory 223 (S305). On the other hand, if at least one of the internal temperature and humidity is not within the predetermined range (No in S302 or No in S304), the CPU 222 stores the mixed load productivity priority mode as inapplicable in the memory 223 (S306).

[0060] 8, after executing the "application determination process" for the mixed load productivity priority mode, the CPU 222 determines whether the environment is one in which the mixed load productivity priority mode can be applied (S403). If the environment is one in which the mixed load productivity priority mode is not applicable (No in S403), the CPU 222 displays a "notification screen" (FIG. 10) described below on the display 225 to notify the user that the environment is deviating from an environment in which operation in the mixed load productivity priority mode is possible (S406). On the other hand, if the environment is one in which the mixed load productivity priority mode is applicable (Yes in S403), the CPU 222 does not display the "notification screen" (FIG. 10) on the display 225 because there is no need to notify the user that the environment is deviating from an environment in which operation in the mixed load productivity priority mode is possible (S404).

[0061] After controlling the display of the "notification screen," the CPU 222 determines whether the image forming apparatus 101 has been powered off (S405). If the image forming apparatus 101 has been powered off (Yes in S405), the CPU 222 ends the "standby processing." If the image forming apparatus 101 has not been powered off (No in S405), the CPU 222 returns to the processing of S401 and repeats the processing of S401 to S406.

[0062] FIG. 10 is a diagram showing an "alert screen" that is displayed on the display 225 when the image forming apparatus 101 is in standby mode. As shown in FIG. 10, an "alert screen" 801 is displayed on a status line provided below an "initial screen" 800. The "alert screen" 801 displays "Temperature is not suitable for productivity priority mode" to notify the user that the environmental conditions suitable for the mixed load productivity priority mode are not met. Furthermore, the "alert screen" 801 displays "Please set the temperature to 21 to 26°C" to notify the user of the environmental conditions suitable for the mixed load productivity priority mode. Note that although an example in which only "temperature" is displayed as an environmental condition is shown here, "humidity" may also be displayed.

[0063] <Job start processing> Next, the job start processing will be described using Fig. 11 to Fig. 12(b) with reference to Fig. 2. Fig. 11 is a flowchart showing the job start processing of the first embodiment. The job start processing is started by the CPU 222 when a mixed job start instruction is received from the operation unit 224 (or the client PC 103) when the mixed load productivity priority mode is input.

[0064] 11, when the CPU 222 receives an instruction to start a mixed job, it acquires recording material information for the job in order from the first sheet via the acquisition unit 261 and obtains the print order according to the acquired recording material information (S501). The recording material information that the acquisition unit 261 can acquire includes information about the basis weight of the recording material. The CPU 222 saves the acquired recording material information and print order in the memory 223 (S502). The CPU 222 repeats the acquisition (S501) and saving (S502) of the recording material information and print order until no more recording material information is acquired (S503).

[0065] The CPU 222 references the recording material information and print order stored in the memory 223 to determine whether the acquired mixed job is a book job (S504). A book job is a mixed job that, for example, contains a mixture of thick paper and plain paper and satisfies the print order conditions. If the acquired mixed job is not a book job (No in S504), the CPU 222 changes the operating mode to normal print mode (paper type-specific productivity priority mode; the same applies below) and starts printing in the normal print mode (S509). In the normal print mode, a temperature table for the high-speed balanced temperature control mode (FIG. 5(a)) and a temperature table for the low-speed balanced temperature control mode (FIG. 5(b)) are used for each recording material being fed. Therefore, the printing operation may be temporarily stopped when switching the conveying speed or fixing temperature.

[0066] If the acquired mixed job is a book job (Yes in S504), the CPU 222 executes the "application determination process" (see FIG. 9) for the mixed load productivity priority mode described above (S505). After executing the "application determination process" for the mixed load productivity priority mode, the CPU 222 determines whether the environment is applicable to the mixed load productivity priority mode (S506). At this time, the CPU 222 does not display the "notification screen" (FIG. 12(b)) described below on the display 225. If the environment is applicable to the mixed load productivity priority mode (Yes in S506), the CPU 222 starts the print operation in the mixed load productivity priority mode (S507).

[0067] If the environment is not one in which the mixed load productivity priority mode can be applied (No in S506), the CPU 222 references the job execution hold flag stored in the memory 223 and determines whether the job execution hold mode is enabled (S508). For example, a job execution hold flag of "1" indicates that the job execution hold mode is enabled, and a job execution hold flag of "0" indicates that the job execution hold mode is disabled. The job execution hold flag can be set by the user from the "Operation Settings Screen" (FIG. 12(a)) described below before starting the job.

[0068] If the job execution suspension mode is enabled (Yes in S508), the CPU 222 suspends the start of the print operation and displays a "notification screen" (FIG. 12(b)) described below on the display 225 to notify the user that the environment is deviating from one in which the mixed load productivity priority mode is operable. The CPU 222 then repeats the processes of S505, S506, and S508 while suspending the start of the print operation until the environment becomes one in which the mixed load productivity priority mode is applicable, or until "Resume printing" (e-1) on the "notification screen" shown in FIG. 12(b) is operated.

[0069] If the job execution hold mode is not enabled (No in S508), that is, if "Resume Print" (e-1) on the "Notification Screen" described below is operated, the CPU 222 changes the operating mode to the normal print mode and starts the print operation (S509). In this way, if the environmental conditions are not met before the start of the mixed job, the mixed job waits without starting until "Resume Print" (e-1) is operated, and starts in the normal print mode in response to "Resume Print" (e-1) being operated and the normal print mode being entered.

[0070] The above-mentioned "operation setting screen" is shown in Fig. 12(a), and the "notification screen" at the start of a job is shown in Fig. 12(b), and each will be explained. The "operation setting screen" 810 shown in Fig. 12(a) is a screen for setting the operation when the environmental conditions suitable for the mixed load productivity priority mode are not met, and is displayed on the display 225 in response to the user setting productivity priority 1 (c-1) on the "speed / image quality priority adjustment setting screen" (see Fig. 6(c)) and operating "OK."

[0071] In the mixed load productivity priority mode, a situation may arise in which the mode cannot be continued due to environmental conditions (internal temperature and internal humidity). Therefore, the "operation setting screen" 810 is a screen that allows the user to set in advance whether to suspend job execution and wait until the internal temperature and internal humidity fall within a predetermined range (environmental conditions) when the mixed load productivity priority mode is not applicable, or to execute (continue) the job in the "normal print mode." When the user selects "continue printing" (d-1) on the "operation setting screen" 810, the job execution suspension flag is set to "0" so that the job is executed in the "normal print mode." When the user selects "suspend printing" (d-2) on the "operation setting screen" 810, the job execution suspension flag is set to "1" so that the job in the "mixed load productivity priority mode" is suspended.

[0072] The "notification screen" 820 shown in FIG. 12(b) is displayed on the display 225 when the job execution suspension mode is enabled. The "notification screen" 820 notifies the user that the environmental conditions suitable for the mixed-load productivity priority mode are not met and that job execution is suspended until the internal temperature and humidity of the machine fall within a predetermined range (environmental conditions). Therefore, as shown in FIG. 12(b), the "notification screen" 820 displays messages such as "Job suspended," "Productivity priority setting cannot be applied to this environment," and "Printing will resume when the temperature reaches 21°C to 26°C." The "notification screen" 820 also displays "Resume Print" (e-1), which allows the user to resume the suspended job before the internal temperature and humidity of the machine fall within the predetermined range. When the user operates the "Resume Print" (e-1), the job execution suspension flag stored in the memory 223 is updated to "0," and printing resumes in the normal print mode. The "notification screen" 820 displays a message urging the user to switch to the normal print mode.

[0073] <Processing during job execution> Next, the job in-progress processing will be described using Fig. 13 while referring to Fig. 2. Fig. 13 is a flowchart showing the job in-progress processing according to the first embodiment. The job in-progress processing is repeatedly executed by the CPU 222 for each recording material page until the currently executing mixed job is completed.

[0074] 13, during execution of a mixed job, the CPU 222 acquires recording material information for multiple sheets of recording material from the next page onwards via the acquisition unit 261, obtains the print order according to the acquired recording material information, and saves the acquired recording material information and print order in the memory 223 (S601). The CPU 222 repeats acquiring and saving the recording material information and print order until no more recording material information can be obtained.

[0075] The CPU 222 determines whether the job including multiple sheets of recording material from the next page onward is a book job (S602) by referring to the recording material information and print order stored in the memory 223. If it is not a book job (No in S602), the CPU 222 changes the operating mode from the mixed sheet productivity priority mode to the normal print mode, and performs printing in the normal print mode (S609).

[0076] If it is a book job (Yes in S602), the CPU 222 executes the "application determination process" (see FIG. 9) for the mixed load productivity priority mode described above (S603). After executing the "application determination process" for the mixed load productivity priority mode, the CPU 222 determines whether the environment is one in which the mixed load productivity priority mode can be applied (S604). If the environment is one in which the mixed load productivity priority mode can be applied (Yes in S604), the CPU 222 determines whether a print operation is currently being performed in the mixed load productivity priority mode (S605). At this time, the CPU 222 does not display the "notification screen" (FIG. 12(b)) described above on the display 225.

[0077] If the printing operation is currently being performed in the mixed stack productivity priority mode (Yes in S605), the CPU 222 continues the printing operation in the mixed stack productivity priority mode. On the other hand, if the printing operation is not currently being performed in the mixed stack productivity priority mode (No in S605), the CPU 222 changes the operating mode to the mixed stack productivity priority mode (S606) and performs the printing operation in the mixed stack productivity priority mode. In this way, if the internal temperature and humidity of the machine satisfy the environmental conditions while the job is being executed, the printing operation is performed in the mixed stack productivity priority mode.

[0078] On the other hand, if the environment is not one in which the mixed load productivity priority mode can be applied (No in S604), the CPU 222 determines whether or not a print operation is currently being performed in the mixed load productivity priority mode (S607).If a print operation is currently being performed in the mixed load productivity priority mode (Yes in S607), the CPU 222 references the job execution hold flag stored in the memory 223 and determines whether or not the job execution hold mode is enabled (S608).

[0079] If the job execution suspension mode is enabled (Yes in S608), the CPU 222 temporarily suspends the printing operation and displays the above-mentioned "notification screen" (FIG. 12(b)) on the display 225 to notify the user that the environment is deviating from one in which the mixed load productivity priority mode can be used. The CPU 222 then repeats the processes of S603, S607, and S608 while the printing operation is temporarily suspended until the environment becomes one in which the mixed load productivity priority mode can be applied, or until "Resume printing" (e-1) on the "notification screen" shown in FIG. 12(b) is operated.

[0080] If the job execution suspension mode is not enabled (No in S608), that is, if "Resume Print" (e-1) on the "Notification Screen" is operated, the CPU 222 changes the operating mode to the normal print mode and resumes the print operation (S609). In this way, if the environmental conditions are not met while a mixed job is being executed in the mixed stack productivity priority mode, the mixed job is temporarily suspended until "Resume Print" (e-1) is operated, and when "Resume Print" (e-1) is operated and the normal print mode is entered, the mixed job is started in the normal print mode. Note that if the print operation is not being executed in the mixed stack productivity priority mode (No in S607), the CPU 222 continues the print operation in the changed normal print mode.

[0081] As described above, in this embodiment, in the "mixed load productivity priority mode" in which mixed jobs in which recording materials with different fixing temperatures are mixed are executed using a common temperature, if the environmental conditions for ensuring the fixability of the toner image are not met, the user is notified that the environmental conditions are not suitable for the mixed load productivity priority mode. This allows the user to understand whether the environment is suitable for the mixed load productivity priority mode, and therefore printing operations using a common temperature in the "mixed load productivity priority mode" are not performed in environmental conditions in which the image quality of the toner image may deteriorate.

[0082] [Second embodiment] As described above, in the job start processing (see FIG. 11 ) of the first embodiment, the start of the print operation is suspended until the environment becomes one in which the mixed load productivity priority mode can be applied, or until the “Resume Printing” (e-1) button on the “Notification Screen” shown in FIG. 12B is operated. In addition, in the job execution processing (see FIG. 13 ) of the first embodiment, the print operation is temporarily suspended until the environment becomes one in which the mixed load productivity priority mode can be applied, or until the “Resume Printing” (e-1) button on the “Notification Screen” shown in FIG. 12B is operated. Then, in response to the user’s operation of “Resume Printing” (e-1), the print operation is performed in the normal print mode. However, for users who prioritize productivity, it is undesirable to have the print operation suspended until the environment becomes one in which the mixed load productivity priority mode can be applied, or until the “Resume Printing” (e-1) button is operated. Therefore, even in an environment in which the mixed load productivity priority mode cannot be applied, there is a desire to forcibly apply the mixed load productivity priority mode and perform the print operation. Below, a second embodiment that realizes this is described for different cases.

[0083] <Job start processing> First, the job start processing of the second embodiment will be described using FIGS. 14 and 15 while also referring to FIG. 2. FIG. 14 is a flowchart showing the job start processing of the second embodiment. Compared to the job start processing of the first embodiment described above (see FIG. 11), the job start processing of the second embodiment shown in FIG. 14 differs in S520, S521, and S522. Therefore, the processing of S520, S521, and S522 will be mainly described below, and the same steps as those in the job start processing of the first embodiment will be assigned the same step numbers and their descriptions will be simplified or omitted.

[0084] If the mixed job is a book job (Yes in S504), the CPU 222 executes an "application determination process" (see FIG. 9) (S505). After executing the "application determination process" for the mixed load productivity priority mode, the CPU 222 determines whether the environment is one in which the mixed load productivity priority mode can be applied (S506). If the environment is not one in which the mixed load productivity priority mode can be applied (No in S506), the CPU 222 determines whether "forced application" of the mixed load productivity priority mode has been selected (S520). For example, a forced application flag of "0" indicates that "forced application" has not been selected, a forced application flag of "1" indicates that "forced application" has been selected and the mixed load productivity priority mode will be forcibly applied, and a forced application flag of "2" indicates that "forced application" has been selected and the mixed load productivity priority mode will not be forcibly applied. The forced application flag can be selected by the user from the "forced application selection screen" (FIG. 15), which will be described later.

[0085] If "forcibly applying" the mixed load productivity priority mode has been selected (Yes in S520), the CPU 222 jumps to the processing of S522. If "forcibly applying" the mixed load productivity priority mode has not been selected (No in S520), the CPU 222 suspends the start of the print operation and displays a "forcible application selection screen" (FIG. 15) described below on the display 225 (S521). Then, the CPU 222 references the forcible application flag stored in the memory 223 and determines whether or not to forcibly apply the mixed load productivity priority mode (S522).

[0086] For example, if the forced application flag is "1" and the mixed load productivity priority mode is to be forcibly applied (Yes in S522), the CPU 222 starts the print operation in the mixed load productivity priority mode even if the environmental conditions are not satisfied (S507). If the forced application flag is "2" and the mixed load productivity priority mode is not to be forcibly applied (No in S522), the CPU 222 refers to the job execution hold flag stored in the memory 223 and determines whether the job execution hold mode is enabled (S508).

[0087] If the job execution hold mode is enabled (Yes in S508), the CPU 222 displays the above-mentioned "notification screen" (FIG. 12(b)) on the display 225 to notify the user that the environment is outside the range in which operation in the mixed load productivity priority mode is possible. On the other hand, if the job execution hold mode is not enabled (No in S508), the CPU 222 changes the operation mode to the normal print mode and starts the print operation (S509).

[0088] The "forced application selection screen" displayed at the start of a job will be described with reference to FIG. 15 . As shown in FIG. 15 , the "forced application selection screen" 830 displays a message such as "The temperature is not suitable for the productivity priority mode" to notify the user that the environmental conditions suitable for the mixed load productivity priority mode are not met. In other words, the "forced application selection screen" also serves as a "notification screen." The "forced application selection screen" 830 also displays a message such as "Do you want to start the job in productivity priority mode?" to prompt the user to select whether to forcibly apply the mixed load productivity priority mode, i.e., to forcibly execute the mixed job in the mixed load productivity priority mode. The "forced application selection screen" 830 has two options, "Yes" (f-1) and "No" (f-2), to allow the user to select whether to forcibly apply the mixed load productivity priority mode. When the user selects "Yes" (f-1), the forced application flag is stored in the memory 223 as "1." When the user selects "No" (f-2), the forced application flag is stored in the memory 223 as "2."

[0089] <Processing during job execution> Next, the job execution processing of the second embodiment will be described using FIGS. 16 to 18 with reference to FIG. 2. FIGS. 16 and 17 are flowcharts showing the job execution processing of the second embodiment. For convenience of illustration, the series of job execution processing steps are divided into two. Compared to the job execution processing step of the first embodiment described above (see FIG. 13), the job execution processing step of the second embodiment shown in FIGS. 16 and 17 differs in S620, S621, and S622. Therefore, the following mainly describes the processing steps of S620, S621, and S622, and the same steps as those in the job execution processing of the first embodiment are assigned the same step numbers, and their description will be simplified or omitted.

[0090] As shown in FIG. 16, the CPU 222 stores recording material information and a printing order in the memory 223 (S601). The CPU 222 references the recording material information and the printing order stored in the memory 223 and determines whether a job including multiple sheets of recording material from the next page onward is a book job (S602). If it is not a book job (No in S602), the CPU 222 jumps to the process of S609 shown in FIG. 17. If it is a book job (Yes in S602), the CPU 222 executes the "application determination process" (see FIG. 9) (S603) and determines whether the environment is applicable to the mixed stack productivity priority mode (S604). If the environment is applicable to the mixed stack productivity priority mode (Yes in S604), the CPU 222 executes the process of S605 shown in FIG. 17. On the other hand, if the environment is not applicable to the mixed stack productivity priority mode (No in S604), the CPU 222 executes the process of S607 shown in FIG. 17.

[0091] 17, if a print operation is currently being performed in the mixed load productivity priority mode (Yes in S607), it is determined whether or not "forced application" of the mixed load productivity priority mode has been selected (S620). The forced application flag can be selected by the user from the "forced application selection screen" (FIG. 18) described later.

[0092] If "forcibly applying" the mixed load productivity priority mode has been selected (Yes in S620), the CPU 222 jumps to the processing of S622. If "forcibly applying" the mixed load productivity priority mode has not been selected (No in S620), the CPU 222 temporarily suspends the print operation and displays a "forcibly applying selection screen" (FIG. 18) described below on the display 225 (S621). Then, the CPU 222 references the forcible application flag stored in the memory 223 and determines whether or not to forcibly apply the mixed load productivity priority mode (S622).

[0093] For example, if the forced application flag is "1" and the mixed load productivity priority mode is to be forcibly applied (Yes in S622), the CPU 222 starts the print operation in the mixed load productivity priority mode. If the forced application flag is "2" and the mixed load productivity priority mode is not to be forcibly applied (No in S622), the CPU 222 refers to the job execution hold flag stored in the memory 223 and determines whether the job execution hold mode is enabled (S608).

[0094] If the job execution hold mode is enabled (Yes in S608), the CPU 222 displays the above-mentioned "notification screen" (FIG. 12(b)) on the display 225 to notify the user that the environment is outside the range in which operation in the mixed load productivity priority mode is possible. On the other hand, if the job execution hold mode is not enabled (No in S608), the CPU 222 changes the operation mode to the normal print mode and starts the print operation (S609).

[0095] The "forced application selection screen" displayed during job execution will be described with reference to FIG. 18 . As shown in FIG. 18 , the "forced application selection screen" 840 displays a message saying, "The temperature has moved out of the range suitable for the productivity priority mode." in order to notify the user that the environmental conditions are no longer suitable for the mixed load productivity priority mode. In other words, the "forced application selection screen" also serves as a "notification screen." Furthermore, to prompt the user to select whether or not to forcibly apply the mixed load productivity priority mode, a message such as "Do you want to continue the job in productivity priority mode?" is displayed. The "forced application selection screen" 840 then displays "Yes" (g-1) and "No" (g-2) to prompt the user to select whether or not to forcibly apply the mixed load productivity priority mode. When the user selects "Yes" (g-1), the forced application flag is stored in the memory 223 as "1." When the user selects "No" (g-2), the forced application flag is stored in the memory 223 as "2."

[0096] As described above, according to this embodiment, in the "mixed load productivity priority mode" in which mixed jobs are executed using a common temperature, even under environmental conditions in which the image quality of the toner image may be degraded, printing operations are performed in the "mixed load productivity priority mode" according to the user's selection. Therefore, for users who want to prioritize productivity, even in an environment in which the mixed load productivity priority mode cannot be applied, the mixed load productivity priority mode can be forcibly applied to execute mixed jobs, and productivity of recording materials can be prevented from decreasing. [Explanation of symbols]

[0097] 101...image forming apparatus, 222...execution unit (CPU), 224...input unit (operation unit), 225...display unit (display), 228...image forming unit (imaging unit), 252...detection unit (temperature and humidity sensor), 261...acquisition unit, 311...fixing unit (fixing device), 401...first rotating body (fixing belt), 402...second rotating body (pressure roller), N...fixing nip unit

Claims

1. An image forming apparatus, an image forming unit that forms a toner image on a recording material; a fixing unit including a first rotating body and a second rotating body that contacts the first rotating body to form a fixing nip portion that sandwiches and conveys the recording material, and that applies heat and pressure to the recording material on which a toner image has been formed to fix the toner image to the recording material; an execution unit capable of executing a continuous image forming job in which a first recording material of the first basis weight and a second recording material of the second basis weight are mixed in one of an operation mode of a first mode in which a fixing temperature, which is a set temperature of the first rotating body, is set to a first temperature when the basis weight of the recording material is a first basis weight, and to a second temperature lower than the first temperature when the basis weight of the recording material is a second basis weight which is smaller than the first basis weight, and a second mode in which a common temperature is set regardless of the basis weight of the recording material; an input unit capable of inputting an operation mode of either the first mode or the second mode; a detection unit for detecting an internal temperature and humidity in the image forming apparatus; a display unit that displays a message that the second mode cannot be applied to the continuous image forming job when the second mode is input to the input unit and the internal temperature and humidity detected by the detection unit do not both satisfy a condition that they are within a predetermined range, An image forming apparatus characterized by:

2. the execution unit does not execute the continuous image forming job until the condition is satisfied, and executes the continuous image forming job in the second mode in response to the condition being satisfied.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. the display unit displays a message that the second mode is not applicable and a message that prompts the user to switch to the first mode.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

4. when the condition is not satisfied before the start of the continuous image forming job, the execution unit waits without starting the continuous image forming job until the first mode is input to the input unit, and starts the continuous image forming job in the first mode in response to the first mode being input to the input unit.

4. The image forming apparatus according to claim 3, wherein the image forming apparatus is a recording medium.

5. when the condition is not satisfied during execution of the continuous image forming job in the second mode, the execution unit suspends the continuous image forming job until the first mode is input to the input unit, and resumes the continuous image forming job in the first mode in response to the first mode being input to the input unit.

4. The image forming apparatus according to claim 3, wherein the image forming apparatus is a recording medium.

6. the display unit displays a message that the second mode is not applicable and a message that prompts the user to select forcibly executing the continuous image forming job in the second mode.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

7. when the condition is not satisfied before the start of the continuous image forming job, the execution unit waits without starting the continuous image forming job until the selection is made, and starts the continuous image forming job in the second mode in response to the selection being made even if the condition is not satisfied.

7. The image forming apparatus according to claim 6, wherein the image forming apparatus is a recording medium.

8. when the condition is not satisfied during execution of the continuous image forming job in the second mode, the execution unit suspends the continuous image forming job until the selection is made, and resumes the continuous image forming job in the first mode in response to the selection being made.

7. The image forming apparatus according to claim 6, wherein the image forming apparatus is a recording medium.

9. When the execution unit executes the continuous image forming job in the second mode, When the continuous image forming job is a job in which the first recording material is not continuously formed for a first number of sheets or more and the second recording material is continuously formed for a second number of sheets or more after the first recording material, the second temperature is set to the common temperature.

9. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

Images