Image forming apparatus

Abstract

The present invention provides an image forming apparatus that can perform continuous fixing operations on different types of recording materials without causing fixing failures or interrupting the process midway. [Solution] An image forming apparatus comprising: a fixing device for fixing a toner image onto a recording material; and a control means for fixing a toner image continuously onto a plurality of recording materials, each containing a first basis weight recording material and a second basis weight recording material smaller than the first basis weight, using the fixing device, provided that the first basis weight recording material is not continuous with the second basis weight recording material, at a constant temperature common to both the first basis weight recording material and the second basis weight recording material.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile apparatus, or a multifunction machine having a plurality of these functions, which fixes a toner image on a recording material.

Background Art

[0002] An image forming apparatus using an electrophotographic method or an electrostatic recording method has a fixing device for fixing an unfixed toner image on a recording material onto the recording material.

[0003] As a fixing device, a configuration having a heating rotating body provided with a heat source for heating an unfixed toner image and a pressure roller for pressing the heating rotating body is known. Further, the fixing device has a contact / separation mechanism and is movable between a position where the pressure rotating body 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, the heat and pressure necessary for fixing are applied, and the toner image is fixed on the recording material.

[0004] When fixing a toner image on a recording material, the larger the basis weight of the recording material, the larger the amount of heat taken away depending on the type of the recording material. Therefore, it is necessary to increase the fixing temperature of the fixing device as the basis weight of the recording material increases. Therefore, temperature control is performed to change the temperature of the heating rotating body according to the type of the recording material. Thereby, the amount of heat applied to the toner image on the recording material is appropriately controlled.

[0005] However, for this reason, when continuously fixing different types of recording materials, every time the type of the recording material changes, the continuous fixing operation must be interrupted until the temperature of the heating rotating body is changed to the optimum temperature control temperature according to the type of the recording material.

[0006] Thus, when fixing to different types of recording materials consecutively, changing the temperature control to the optimal temperature for each type of recording material can improve the image quality of the toner image formed on the recording material, but it will also reduce productivity.

[0007] Therefore, Patent Document 1 discloses a productivity-prioritizing mode in which, when fixing to different types of recording materials consecutively, fixing is performed at a constant temperature common to each type of recording material, within the allowable temperature range of each type of recording material, without changing the temperature for each type of recording material, and without interrupting the continuous fixing operation. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2005-321478 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, the productivity-prioritizing mode disclosed in Patent Document 1 does not take into account that the temperature of the fixing device decreases due to heat loss by the recording material. As a result, when recording materials with a large basis weight are fixed consecutively, a large amount of heat is lost, preventing the device from returning to a common constant temperature control temperature within the allowable temperature range for each type of recording material, thus causing fixing failures.

[0010] This invention has been made in view of the above circumstances, and aims to provide an image forming apparatus that can perform continuous fixing operations on different types of recording materials without causing fixing failures and without interrupting the process. [Means for solving the problem]

[0011] To achieve the above objective, the present invention provides an image forming apparatus comprising: a fixing device for fixing a toner image onto a recording material; and a control means for fixing a toner image at a constant temperature common to both the first and second basis weight recording materials when the fixing device continuously fixes a toner image onto a plurality of recording materials in which a first basis weight recording material and a second basis weight recording material smaller than the first basis weight are mixed, provided that the first basis weight recording material is not continuous with the second basis weight recording material. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an image forming apparatus that can perform continuous fixing operations on different types of recording materials without causing fixing failures or interrupting the process midway. [Brief explanation of the drawing]

[0013] [Figure 1] This is a configuration diagram of an image processing system according to an embodiment of the present invention. [Figure 2] This is a system configuration diagram of the image processing system shown in Figure 1, according to an embodiment of the present invention. [Figure 3] This is a configuration diagram of the image forming apparatus shown in Figure 1 according to an embodiment of the present invention. [Figure 4] This is an enlarged cross-sectional view of a fixing device according to an embodiment of the present invention. [Figure 5] This is an explanatory diagram of a display that sets a book-priority temperature control mode according to an embodiment of the present invention. [Figure 6] This table shows the relationship between the type of media and the temperature control temperature for each temperature control mode according to an embodiment of the present invention. [Figure 7] This is an explanatory diagram illustrating the fixing sequence of a job including a cover / laminated sheet according to an embodiment of the present invention. [Figure 8] Figure 2 is a flowchart of the CPU 222 according to an embodiment of the present invention. [Modes for carrying out the invention]

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the components described in the following embodiments are merely examples, and various conditions such as the configuration, function, dimensions, material, shape, relative arrangement, etc. of the apparatus to which the present invention is applied can be appropriately modified or changed without departing from the gist of the present invention, and the present invention is not limited to the following embodiments.

[0015] FIG. 1 is a configuration diagram of an image processing system according to an embodiment of the present invention.

[0016] In FIG. 1, 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 device, a multifunction peripheral (MFP), or the like. The external controller is, for example, an image processing controller, a digital front end (DFE), a print server, or the like.

[0017] 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.

[0018] 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 on the client PC 103. The user can instruct printing via the printer driver using various applications. The printer driver transmits image data to the external controller 102 based on the print job from the user. The external controller 102 receives a print job including image data from the client PC 103, performs data analysis and rasterization processing, and instructs the image forming apparatus 101 to perform printing (image formation) based on the image data.

[0019] The image forming apparatus 101 is configured by connecting devices having a plurality of different functions including a printing apparatus 107, and can perform complex printing processes such as bookbinding. The image forming apparatus 101 of the present embodiment includes a printing apparatus 107 and a finisher 109. The printing apparatus 107 forms an image on a recording material fed from a paper feeding unit provided at the lower part of the main body using a developer (for example, toner). The printing apparatus 107 forms images of 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 is formed is conveyed from the printing apparatus 107 to the finisher 109. The finisher 109 stacks the recording materials on which the images are formed.

[0020] This image processing system is configured such that an external controller 102 is 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 a print job including image data from the client PC 103 via the external LAN 104. In this case, the image forming apparatus 101 performs data analysis and rasterization processing that are performed by the external controller 102. That is, the image forming apparatus 101 and the external controller 102 may be integrally configured.

[0021] FIG. 2 is a system configuration diagram for controlling the operation of the image processing system of FIG. 1. Here, the controller for controlling the operation of each of the image forming apparatus 101, the external controller 102, and the client PC 103 will be described.

[0022] In FIG. 2, the printing apparatus 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 apparatus 107 includes a CPU (Central Processing Unit) 222, a memory 223, a storage 221, and an image processing unit 232 for controlling the operation of the printing apparatus 107.

[0023] The printing apparatus 107 comprises an exposure unit 227, an image-making unit 228, a fixing unit 311, and a paper-feed unit 230 for forming an image. The printing apparatus 107 also includes an operation unit 224 and a display 225 as a user interface. The printing apparatus 107 also 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 relative to 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The transfer unit has an intermediate transfer belt 308, as shown in Figure 3, which will be described later, and 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 308. The toner image formed on the intermediate transfer belt 308 is then transferred to the recording material by a secondary transfer roller 309, as shown in Figure 3, which will be described later. When a positive potential is applied to the secondary transfer roller 309, it transfers the full-color toner image from the intermediate transfer belt 308 to the recording material.

[0029] 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, thereby 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 to control the feeding operation of the recording material.

[0030] 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.

[0031] 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.

[0032] 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 output 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.

[0033] The CPU 242 executes the control program stored in the memory 243 and performs various controls necessary for paper ejection. The memory 243 stores the control program. The memory 243 also provides a work area for the CPU 242 to perform various processes. The paper ejection control unit 244 ejects the transported recording material based on instructions from the CPU 242.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Client PC 103 includes a CPU 201, memory 202, storage 203, keyboard 204, display 205, and LAN I / F 206. These components are interconnected via a system bus 207 so that they can communicate with each other.

[0038] 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.

[0039] 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.

[0040] Figure 3 is a diagram showing the configuration of the image forming apparatus 101.

[0041] In Figure 3, a display 225 is provided on top of the printing device 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 device 107 is transported to the finisher 109 located downstream.

[0042] 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.

[0043] 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 an exposure unit 227 and an image forming unit 228, which are image forming units 304, 305, 306, and 307 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).

[0044] The printing apparatus 107 includes an image-forming unit 228, an intermediate transfer belt 308 and a secondary transfer roller 309, to 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 Figure 3, 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 to the transported recording material.

[0045] The printing apparatus 107 includes a fixing device 311. The fixing device 311 fixes the toner image onto the recording material. To this end, 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 a nip 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.

[0046] 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). For this purpose, 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.

[0047] 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.

[0048] 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.

[0049] Next, the details of the configuration of the fixing device 311 in this embodiment will be described using Figure 4. Figure 4 is an enlarged cross-sectional view of the fixing device 311 in this embodiment.

[0050] In Figure 4, the recording material is transported from right to left. 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 section 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, 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.

[0051] The heating roller 404 has a halogen heater (not shown) inside and is capable of generating heat to a predetermined temperature. The belt 401 is heated by the heating roller 404 and controlled to a fixing temperature according to the type (basis weight) of the recording material based on temperature detection by a thermistor. The thermistor may be configured to detect the surface temperature of the heating roller 404, or it may detect the temperature of the belt 401.

[0052] 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. When the recording material carrying the unfixed toner image is clamped 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.

[0053] In a fixing device, the larger the basis weight of the recording material, the greater the amount of heat required to fix the toner image, so it is necessary to set the temperature control temperature higher.

[0054] Therefore, when fixing continuously to recording materials with different basis weights, the continuous fixing operation must be interrupted each time the basis weight of the recording material changes until the temperature control temperature of the fixing device is changed to the optimal temperature control temperature corresponding to the basis weight of the recording material (the normal temperature control temperature as the first temperature control temperature in Figure 6).

[0055] Thus, when fixing to recording materials of different basis weights in succession, changing the temperature control to the optimal temperature for each basis weight of the recording material can improve the image quality of the toner image formed on the recording material by setting the optimal temperature control to the appropriate temperature for the basis weight of the recording material (normal temperature control in Figure 6). However, this also reduces productivity because the continuous fixing operation must be interrupted each time the basis weight of the recording material changes until the temperature control of the fixing device is changed to the optimal temperature control to the appropriate temperature for the basis weight of the recording material (normal temperature control in Figure 6).

[0056] In contrast, in this embodiment, in a print job including a cover / laminated paper, when the basis weight of the cover / laminated paper is greater than the basis weight of the inner paper, a book-priority temperature control mode is provided that fixes both the cover / laminated paper and the inner paper at a constant temperature lower than the normal temperature control temperature in Figure 6 (a temperature control temperature corresponding to the type of cover / laminated paper as the second temperature control temperature for the cover / laminated paper in Figure 6), which prevents the inner paper with the smaller basis weight from curling, and allows for continuous fixing without interruption of the process without changing the temperature control temperature between the cover / laminated paper and the inner paper.

[0057] In this case, provided that the cover / laminated paper is not continuous with the inner paper, even if the temperature control temperature for the cover / laminated paper in Figure 6 is set lower than the normal temperature control temperature in Figure 6, it is ensured that after a large amount of heat is removed by the larger basis weight cover / laminated paper, the temperature will return to the target temperature for the cover / laminated paper by the smaller basis weight inner paper, which removes less heat, thus preventing fixing failures.

[0058] The user can set the aforementioned book-priority temperature control mode from the settings screen displayed on the display 225 via the CPU 222.

[0059] Figure 5 is an explanatory diagram of the display for setting book priority temperature control.

[0060] In Figure 5, Figure 5(A) is the initial screen. When the user selects the "Application Mode" soft key from the initial screen, the CPU 222 displays the application mode selection screen shown in Figure 5(B) on the display 225. When the user selects the "Cover / Laminate" soft key from the application mode selection screen, the CPU 222 displays the screen shown in Figure 5(C) on the display 225 for selecting the cover / laminate recording material and setting whether or not to print on the cover. Also, when "Paper Selection" is selected, the display 225 displays the setting screen for the paper feed decks 301 and 302, which contain the recording material shown in Figure 5(D).

[0061] When a user outputs a print job that includes a cover / interlining, they can input settings via the control unit 224, specifying which page of the job the cover / interlining should be printed on, and selecting the recording materials for the cover / interlining / inner pages.

[0062] Jobs that include covers and interleavings often involve a mix of recording materials with different basis weights.

[0063] Figure 7 is an explanatory diagram illustrating the fixing sequence of a job, including the cover / laminated pages.

[0064] In Figure 7, Figure 7(A) shows an example where the cover is made of coated paper 7 and the inner pages (body pages) are made of plain paper 1. In this case, if the temperature control is set to the normal temperature control temperature, as shown in Figure 6, the temperature control temperature of the first and seventh sheets of coated paper 7 will be 182°C, and the temperature control temperature of the second to sixth sheets of plain paper 1 will be 175°C.

[0065] Figure 7(B) shows an example where the main text pages are made of thick paper 4, and the interleaving sheets inserted in the middle of the text are made of plain paper 1. In this case, if the temperature control is set to the normal temperature control temperature, the temperature control temperature for the 1st, 3rd, 4th, 5th, and 7th sheets of thick paper 4 will be 178°C, and the temperature control temperature for the 2nd and 6th sheets of plain paper 1 will be 175°C.

[0066] In both Figures 7(A) and (B), when the temperature control temperature is switched, the continuous fixing operation that is performed until the new temperature is reached is interrupted, resulting in a decrease in productivity.

[0067] In contrast, in the case of print jobs including covers / laminated paper as described above, even with recording materials of different basis weights, selecting the aforementioned book-priority temperature control mode and setting the temperature control temperature for the print job to a single temperature eliminates the need to wait for temperature changes between recording materials, allowing for continuous fixing operations without reducing productivity.

[0068] Furthermore, users can choose to change settings such as setting the book-priority temperature control mode if they frequently insert covers and interleaving sheets and want to avoid decreased productivity due to frequent waiting for temperature control settings to switch, or clearing the book-priority temperature control mode if they want to select a temperature setting appropriate for the recording material and prioritize image quality. Various input methods are available for users to change these settings, including input from the control unit 224 and settings in the printer driver.

[0069] Figure 8 is a flowchart of the CPU 222 in Figure 2 that determines the fuser temperature control temperature. This flowchart shows the process of the book-priority temperature control mode, which speeds up the time until printing is completed, by setting the temperature control temperature of the fuser unit 311 based on the input print job, whether or not the book-priority temperature control mode is set, and information on the cover / interlining recording material.

[0070] This process begins when the printing device 107 receives a print job start instruction from the operation unit 224 or the client PC 103.

[0071] In step S101, the CPU 222 determines whether the user has set the book priority temperature control mode.

[0072] If the book priority temperature control mode is not set in step S101, the process proceeds to step S102, where the normal temperature control temperature shown in Figure 6 is set for each page according to the type of recording material.

[0073] If the book priority temperature control mode is set in step S101, proceed to step S103 to determine if a cover / interleaving job has been selected by the user.

[0074] If a cover / laminated paper job was not selected in step S103, the process proceeds to step S102, where the normal temperature control temperature shown in Figure 6 is set for each page according to the type of recording material.

[0075] On the other hand, if a cover / interlining job is selected in step S103, the process proceeds to steps S104 and S105, where the user selects the recording material to be used for the cover / interlining and the recording material to be used for the inner pages.

[0076] Next, in step S106, if the basis weight of the cover / laminated paper recording material selected in step S104 is greater than the basis weight of the inner paper selected in step S105, and the cover / laminated paper is not continuous with the inner paper, the process proceeds to step S107; otherwise, the process proceeds to step S102, where the normal temperature control temperature shown in Figure 6 is set for each page according to the type of recording material.

[0077] In step S106, if the basis weight of the cover / laminated recording material selected in step S104 is greater than the basis weight of the inner paper selected in step S105, and the cover / laminated is not continuous with the inner paper, then in step S107, the temperature control temperature for the cover / laminated, as shown in Figure 6, corresponding to the cover / laminated recording material selected in step S104, is set to the temperature control temperature for all recording materials in the print job.

[0078] As described above, in the case of Figure 7(A), the basis weight of the coated paper 7, which is the cover, is greater than that of the plain paper 1, which is the inner sheet, and the cover is not continuous with the inner sheet. Therefore, the cover / laminated paper temperature control can be applied, and the temperature control temperature of both the coated paper 7 and the plain paper 1 is set to the cover / laminated paper temperature control temperature of 180°C for the coated paper 7. This applies a book-priority temperature control mode that prioritizes productivity, allowing continuous fixing operations to be performed at a constant temperature without interruption and without reducing productivity.

[0079] On the other hand, in the case of Figure 7(B), since the basis weight of the plain paper 1 used as the interlining is smaller than that of the cardboard 4 used as the inner sheet, a constant temperature control temperature for the cover / interlining that is common to both the plain paper 1 and the cardboard 4 cannot be set. For this reason, the normal temperature control temperature of 175°C is applied to the plain paper 1 and 182°C to the cardboard 4, and the book-priority temperature control mode, which prioritizes productivity and allows continuous fixing operations to be performed at a constant temperature without interruption and without reducing productivity, is not applied.

[0080] In the above embodiment, a book-priority temperature control mode can be applied when the basis weight of the cover / laminated paper is greater than that of the inner paper, and the cover / laminated paper is not continuous with respect to the inner paper, allowing for continuous fixing at a common, constant temperature without interruption. However, this is not limited to the relationship between the basis weights of the cover / laminated paper and the inner paper. It can be applied to recording materials with different basis weights, where the recording material with the larger basis weight is not continuous with respect to the recording material with the smaller basis weight, as a fixing mode that allows for continuous fixing at a common, constant temperature without interruption, similar to the book-priority temperature control mode described above.

[0081] As described in the embodiments above, in mixed jobs where recording materials with different basis weights are mixed, a productivity-prioritizing mode can be set that enables continuous fixing operations without interruption due to waiting for temperature switching, even if the recording material with the larger basis weight does not draw a large amount of heat from the fixing device, by setting the temperature control temperature of the fixing device to a common, constant temperature, thereby preventing fixing failures. [Explanation of symbols]

[0082] 101…Image forming apparatus 102...External controller 103…Client PC 222…CPU 311... Fixing device

Claims

1. A fixing device for fixing toner images onto recording material, When fixing toner images continuously to a plurality of recording materials, each containing a recording material of a first basis weight and a recording material of a second basis weight smaller than the first basis weight, using the fixing device, a control means is provided to fix the toner images at a constant temperature common to both the recording material of the first basis weight and the recording material of the second basis weight, provided that the recording material of the first basis weight is not continuous with the recording material of the second basis weight. An image forming apparatus characterized by having the following features.

2. The image forming apparatus according to claim 1, characterized in that, when the recording material of the first basis weight is continuous with the recording material of the second basis weight, the control means fixes a toner image to the recording material of the first basis weight at a temperature controlled for fixing a toner image to the recording material of the first basis weight, and fixes a toner image to the recording material of the second basis weight at a temperature controlled for fixing a toner image to the recording material of the second basis weight that is different from the temperature controlled for fixing a toner image to the recording material of the first basis weight.

3. The image forming apparatus according to claim 1, characterized in that it has a selection means for selecting whether or not to fix a toner image to the first basis weight recording material and the second basis weight recording material at a common constant temperature when the first basis weight recording material is not continuous with the second basis weight recording material.

4. The image forming apparatus according to claim 1, characterized in that, when the first basis weight recording material is not continuous with the second basis weight recording material, the apparatus has a selection means that allows the user to select whether to fix a toner image to the first basis weight recording material and the second basis weight recording material at a common constant temperature, or to fix a toner image to the first basis weight recording material at a temperature suitable for fixing a toner image to the first basis weight recording material, and to fix a toner image to the second basis weight recording material at a temperature suitable for fixing a toner image to the second basis weight recording material that is different from the temperature suitable for fixing a toner image to the first basis weight recording material.

5. The image forming apparatus according to claim 2, characterized in that the common constant temperature is set lower than the temperature for fixing the toner image to the first basis weight recording material.

6. The image forming apparatus according to claim 4, characterized in that the common constant temperature is set lower than the temperature for fixing the toner image to the first basis weight recording material.

7. The image forming apparatus according to any one of claims 1 to 6, characterized in that the first basis weight recording material is a cover or interleaving paper, and the second basis weight recording material is inner paper.

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