JP2011112870A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate wasteful consumption of power, without impairing the convenience of a user. <P>SOLUTION: The image forming apparatus includes a paper feed section; an image forming section for forming a toner image; a heating section, including a rotating body disposed in contact with paper; a fixing device having a varying mechanism for varying the heating width of the rotary body in the axial direction thereof; a plurality of temperature detectors having a regular mode, a low-power mode for decreasing power consumption as compared to the regular mode, and a sleep mode for decreasing the power consumption as compared to the low-power mode, and being used for detecting the temperature of the heating section according to a heating width; a paper-size sensor for detecting the size of paper accommodated in the paper feed section; and a control section for determining the size of paper and controlling mode switching, thereby controlling heating in the fixing device. When only papers corresponding to the heating width which is smaller than the maximum heating width is accommodated in the paper feed section, the control section makes the apparatus shift to sleep mode not via the low-power mode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a multifunction machine, a copying machine, a printer, and a FAX apparatus that heats and fixes a sheet on which a toner image is transferred.

  2. Description of the Related Art Conventionally, some image forming apparatuses such as multifunction peripherals transfer a formed toner image onto a sheet and fix the toner image with heat. In the image forming apparatus, there is provided a fixing device that fixes the toner image by heating while conveying the paper. In the fixing device, for example, hundreds to thousands of watts of electric power is consumed for heating. Therefore, a great power saving effect can be obtained by preventing wasteful power consumption in the fixing device. Therefore, there are cases where a plurality of modes are provided for heating in the fixing device, and the power consumed in the fixing device is made different for each mode to save power. An image forming apparatus having such a plurality of modes is described in Patent Document 1.

  Specifically, Patent Document 1 discloses an image forming apparatus that controls heating of a heating member when fixing the image on the recording paper by passing the recording paper in contact with the heating member and housed in a cassette. When the recording paper size is larger than the predetermined size during the power-saving heating of the detection member that detects the size of the recording paper and the heating member that is not performing image formation, the recording paper that is larger than the predetermined size in the heating member passes. When the recording sheet size is smaller than a predetermined size by heating in the first heat generation mode for heating the sheet passing area to be heated, the second heating section heats the sheet passing area through which the recording sheet having a size smaller than the predetermined size passes. Control means for performing heating in the heat generation mode, and power saving heating is more efficient than the power saving preheating mode and the power saving mode than the heating state during image formation. Image forming apparatus has been described which is selected from the group comprising power standby heating mode. With this configuration, when the size of the recording paper is smaller than the predetermined size, the heating control is performed so as to perform heating necessary for the recording paper of a small size, thereby suppressing wasteful power consumption during the heating control and saving energy. Trying to figure out (see Patent Document 1: Claim 1, Claim 2, paragraph [0013], etc.).

JP2007-199610

  For example, in an image forming apparatus such as a multifunction machine, a normal mode in which the toner is melted and fixed at the fixing control temperature required by the heat of a heating unit including a rotating body in contact with the paper in the fixing device. , Sleep mode that stops supplying power to the fixing device, and maintain the temperature of the heating unit at a temperature lower than the fixing control temperature so that the temperature of the fixing device can reach the fixing control temperature in a shorter time than the sleep mode A low power mode may be provided. In other words, from the viewpoint of power saving, a plurality of modes including power supply OFF to the fixing device may be provided. In general, as time passes without the image forming apparatus being used, the mode shifts to a mode with less power consumption, and the temperature of the heating portion gradually decreases.

  On the other hand, as described in Patent Document 1, there is a case where the heating width is variable by changing the length of the rotating body heated in accordance with the paper size in the axial direction. And since the area | region which warms the one where a heating width is narrow is narrow, the temperature of a heating part can be heated up faster than the case where a heating width is wide. Then, if the heating width is narrow, even if the low power mode is not used, the area (sheet passing area) in contact with the paper in the heating unit can be promptly returned within the time allowed for the user when returning from the sleep mode. Sometimes it can be warmed up (warmed up).

  Depending on the heating width, even when shifting from the normal mode to the sleep mode without using the low power mode, there may be no problem from the viewpoint of user convenience (waiting time until warm-up completion). Regardless of the heating width, the control to shift to the sleep mode is performed after passing from the normal mode to the low power mode. Therefore, there is a problem that useless power may be consumed in the low power mode.

  Incidentally, when the fixing device described in Patent Document 1 is viewed, it is described that the heating is controlled in accordance with the paper (see Patent Document 1: Claim 1). In addition, there is also described a point having a plurality of modes in heating with the fixing device (see Patent Document 1: Claim 1, Claim 2, etc.). However, there is no description or suggestion regarding the problem that wasteful power may be consumed in the low power mode. Therefore, the invention described in Patent Document 1 cannot solve the above problem.

  The present invention has been made in view of the above-described problems of the prior art, and shifts directly from the mode in which the temperature of the paper passing area is maintained at the fixing control temperature to the sleep mode without impairing the convenience of the user. Therefore, it is an object to eliminate wasteful power consumption.

  An image forming apparatus according to a first aspect of the present invention includes a paper feeding unit that stores paper used for printing, an image forming unit that forms a toner image, a heating unit that includes a rotating body that contacts the paper for fixing the toner image, and A fixing device having a variable mechanism that varies a heating width in the axial direction of the rotating body, a normal mode, a low power mode that reduces power consumption supplied to the fixing device than the normal mode, and the low power mode than the low power mode. In an image forming apparatus having a sleep mode for reducing power consumption supplied to a fixing device, a plurality of temperature detectors for detecting the temperature of the heating unit in accordance with a heating width, and a paper size accommodated in the paper feeding unit A paper size sensor for detecting the paper size, a paper size stored in the paper feeding unit based on an output of the paper size sensor, controlling mode switching, and detecting the temperature. And a controller that controls heating in the fixing device based on the output of the body and controls heating in the fixing device, and the controller corresponds to a sheet having a heating width smaller than the maximum heating width. When only the paper feeding unit is accommodated in the paper feeding unit, the mode is shifted to the sleep mode without going through the low power mode, and when returning from the sleep mode to the normal mode, the variable mechanism is controlled to The heating unit is heated to a fixing control temperature necessary for fixing the toner image with a heating width corresponding to the size of the paper stored in the paper unit.

  According to this configuration, when only paper corresponding to a heating width narrower than the maximum heating width is accommodated in the paper feeding unit, the mode is shifted to the sleep mode without going through the low power mode. Can be eliminated. In addition, when returning to the normal mode, the heating unit is heated to the fixing control temperature necessary for fixing the toner image with a heating width narrower than the maximum heating width corresponding to the paper size. In addition, the heating unit is quickly warmed to the fixing control temperature without being lost. Thus, while achieving power saving, warm-up when returning from the sleep mode to the normal mode does not take a long time, and the convenience for the user is not impaired.

  According to a second aspect of the present invention, in the first aspect of the invention, the fixing device is opposed to the heating unit, is wound along the axial direction of the rotating body, and warms the heating unit by induction heating. A coil and the heating unit are opposed to each other, a magnetic path is formed between the coil and the heating unit, a peripheral surface is covered with a magnetic shielding plate, and a heating width for heating the heating unit is made different. A core that is covered by the magnetic shielding plate in a plurality of stages and that has different lengths in the axial direction, and has a rotating unit that rotates the core as the variable mechanism, and the control unit controls the rotating unit. Thus, the heating width in the heating unit is controlled by controlling the rotation angle of the core.

  According to this configuration, the axial length covered by the magnetic shielding plate depending on the position in the circumferential direction includes a plurality of stages of different cores, and includes a rotating unit that rotates the core as a variable mechanism, and the control unit includes the rotating unit Is controlled to control the rotation angle of the core, so that the heating width can be adjusted. In this case, the heating area is narrower when the heating width is narrower than when heating at the maximum heating width, and the portion to be warmed is smaller than the power (for example, the allowable maximum power) supplied to the fixing device. . For example, the density of power that can be input per unit area can be increased when the heating width is narrower than at the maximum heating width. Accordingly, the temperature increase in the sheet passing area to the fixing control temperature can be accelerated when the heating width is narrower than when heating at the maximum heating width.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the mode is shifted to the sleep mode without going through the low power mode, or the mode is shifted to the sleep mode through the low power mode. A setting input unit for receiving setting input is provided.

  According to this configuration, it is possible to set in the setting input unit whether to shift to the sleep mode without going through the low power mode or to shift to the sleep mode through the low power mode, so that the intention of the user is reflected. Control can be performed. For example, a user who places importance on the power saving effect may make a setting for shifting to the sleep mode without going through the low power mode. On the other hand, a user who wants to shorten the return time for returning from a mode other than the normal mode and give priority to convenience may set to shift to the sleep mode via the low power mode.

  According to a fourth aspect of the present invention, in the first to third aspects of the invention, the control unit controls heating in the fixing device, and in the normal mode, the temperature of the heating unit is used to fix a toner image. The temperature is maintained at a necessary fixing control temperature, the temperature of the heating unit is maintained lower than that in the normal mode in the low power mode, and heating of the heating unit is stopped in the sleep mode.

  According to this configuration, a difference in power consumption is surely obtained in each mode. Also, by shifting to the sleep mode without going through the low power mode, it is possible to eliminate waste of power that is consumed reliably.

  According to a fifth aspect of the present invention, in the first to fourth aspects of the present invention, the controller controls the fixing control temperature when returning from the low power mode to the normal mode while heating with the maximum heating width. The time until the heating unit reaches the fixing control temperature necessary for fixing the toner image is shorter than the reference time when returning from the sleep mode using the time until the time reaches the fixing time as the reference time. When only the following sheets are stored in the sheet feeding unit, the mode is shifted to the sleep mode without going through the low power mode.

  According to this configuration, the return time when returning from the low power mode to the normal mode with the maximum heating width is set as the reference time, and only when the return time when returning from the sleep mode to the normal mode is shorter than the reference time. Transition to the normal mode without going through the low power mode. This avoids the transition from the normal mode to the sleep mode without going through the low power mode for the paper whose size is long in the return time when returning from the sleep mode to the normal mode under a certain standard. be able to. User convenience is ensured.

  As described above, according to the present invention, when only a sheet corresponding to a heating width smaller than the maximum heating width is accommodated in the sheet feeding unit, the image forming apparatus enters the sleep mode without going through the low power mode. Transition. Accordingly, it is possible to eliminate wasteful power consumption by shifting directly from the mode in which the temperature of the paper passing area is maintained at the fixing control temperature to the sleep mode without impairing the convenience of the user.

1 is a schematic cross-sectional view illustrating a schematic configuration of a multifunction machine according to an embodiment. FIG. 3 is an enlarged schematic cross-sectional view of one image forming unit according to the embodiment. 1 is a block diagram illustrating an example of a hardware configuration of a multifunction machine according to an embodiment. FIG. 2A is a schematic cross-sectional view of an example of a fixing device according to an embodiment as viewed from the front, and FIG. 2B is a perspective view illustrating an example of a configuration around a heating roller. FIG. 6 is an explanatory diagram for explaining an example of a core of a fixing device according to an embodiment. FIG. 2 is a block diagram illustrating an example of a hardware configuration related to heating control in the fixing device according to the embodiment. 6 is a graph illustrating an example of a time from the start to completion of warming up for causing the temperature of the heating belt or the like to reach the fixing control temperature when returning from the sleep mode to the normal mode in the multifunction peripheral according to the embodiment. 6 is an explanatory diagram illustrating an example of a setting screen on a liquid crystal display unit of the operation panel of the multifunction peripheral according to the embodiment. FIG. 6 is a flowchart illustrating an example of mode transition in the multifunction peripheral and heating control in the fixing device according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 7, taking a multifunction peripheral 100 (corresponding to an image forming apparatus) as an example. However, each element such as configuration and arrangement described in each embodiment does not limit the scope of the invention and is merely an illustrative example.

(Schematic configuration of image forming apparatus)
First, an outline of the multifunction peripheral 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a multifunction peripheral 100 according to an embodiment of the present invention. FIG. 2 is an enlarged schematic cross-sectional view of one image forming unit 42 according to the embodiment of the present invention.

  First, a document transport apparatus 101 that automatically and continuously transports documents one by one to a reading position is attached to the top of the multifunction peripheral 100. An image reading unit 102 is provided below the document conveying device 101. Further, the document conveying apparatus 101 is attached to the image reading unit 102 so as to be freely opened and closed in the vertical direction with the back side of the sheet of FIG. 1 as a fulcrum. Thereby, it functions as a cover for pressing the contact glass (the feed reading contact glass 102A and the placement reading contact glass 102B) from above.

  The image reading unit 102 is provided with a feed reading contact glass 102A and a placement reading contact glass 102B on which an original is placed when reading originals such as books one by one. In the image reading unit 102, a lamp, a mirror, a lens, an image sensor, and the like (not shown) are arranged. The image sensor reads the original based on the reflected light of the original passing through the feed reading contact glass 102A or the original placed on the placement reading contact glass 102B. The image sensor converts the reflected light into an analog electrical signal corresponding to the image density, and then performs quantization to obtain image data.

  In addition, as shown by the broken line in FIG. 1, the multifunction device 100 is provided with the operation panel 1 at the upper front portion. The operation panel 1 is provided with a start key 10 for instructing execution of copying after various settings. The operation panel 1 also includes a numeric keypad 11 for inputting numbers such as the number of copies to be printed, and a liquid crystal display unit 12 for displaying menus and keys for giving settings and operation instructions for the multifunction peripheral 100. The liquid crystal display unit 12 is a touch panel type. The user can press the key displayed on the liquid crystal display unit 12 to set the multifunction device 100 and give an operation instruction. For example, the user can specify the size and type of paper used on the operation panel 1.

  Further, the multifunction peripheral 100 includes a sheet feeding unit 2 (2A to 2D), a conveyance path 3, an image forming unit 4, an intermediate transfer unit 5, a fixing device 6 and the like from below.

  Each sheet feeding unit 2 below the MFP 100 (in FIG. 1, the symbols A, B, C, and D from the top) are used for printing sizes (for example, A4, A5, A6, B4, etc.). A type, B type paper, etc.) and various types of paper (for example, plain paper such as copy paper, recycled paper, thin paper, thick paper, OHP sheets, etc.) are accommodated. For example, the uppermost sheet feeding unit 2A accommodates A3 landscape paper (placed with the paper conveyance direction and the long side direction of A3 paper aligned). The second-stage paper feed unit 2B from the top stores B4 landscape paper (placed with the paper transport direction and the long side direction of the B4 paper aligned). The paper feed unit 2C in the third row from the top accommodates A4 landscape paper (placed with the paper transport direction and the long side direction of the A4 paper aligned). The lowermost paper feed unit 2D accommodates postcards (placed approximately in A6 size, with the paper transport direction and the long side direction of the postcards aligned). Since the configurations of the paper feeding units 2 are the same, the same components are denoted by the same reference numerals, and the symbols A, B, C, and D are omitted unless specifically described.

  Each paper feed unit 2 includes a paper feed roller 21 that is rotationally driven by a paper feed motor (not shown), and feeds the paper to the transport path 3 one by one during printing. In each paper feed unit 2, there are an upper and lower regulation guide 22 that regulates the stacked sheets sandwiched in a direction perpendicular to the sheet conveyance direction, and a rear end regulation guide 23 that regulates the rear end of the sheet in contact with it. Two types of regulation guides are provided. The vertical regulation guides 22 are provided as a pair (only one is visible in FIG. 1) and slides in conjunction with each other. When actually regulating the paper position, the vertical regulation guide 22 is slid to sandwich the paper. As a result, the sheet is regulated so that the center in the width direction of the conveying path 3 (the direction perpendicular to the sheet conveying direction, the direction perpendicular to the paper surface in FIG. 1) coincides with the center axis of the sheet (central sheet passing). The trailing edge regulation guide 23 is also slid to regulate the trailing edge of the sheet.

  Since each regulation guide is slidable, the size of the paper stored in each of the paper feeding units 2A to 2D can be changed as appropriate. For example, a user who hardly uses A3 or B4 paper may store A4 landscape paper in all four stages in each paper feed unit 2. In this way, the user can store sheets of various sizes in each sheet feeding unit 2.

  Each paper feed unit 2 is provided with a paper size sensor 24 for detecting the paper size stored in the paper feed unit 2. For example, the paper size sensor 24 is connected to the rear end regulation guide 23 and has a variable resistance (not shown) whose resistance value changes depending on the slide position, and a variable resistance (not shown) connected to the vertical regulation guide 22 and whose resistance value changes depending on the slide position. (Not shown). Therefore, the paper size sensor 24 outputs different voltages depending on the position of each regulation guide. Note that the paper size sensor 24 may be one that grasps the position of each regulation guide by a plurality of optical sensors, and only needs to be able to grasp the size of the loaded paper.

  Each paper feed unit 2 is removable from the drawer body. When the sheet runs out or when the sheet is replaced, the user pulls out the sheet feeding unit 2 and replenishes or replaces the sheet. Then, the user inserts and attaches the sheet feeding unit 2 into the main body of the multifunction device 100. As shown in FIG. 1, one insertion / removal detection switch 25 is provided for each paper feed unit 2 in order to detect removal and attachment of each paper feed unit 2. The insertion / removal detection switch 25 is switched ON / OFF (for example, an interlock switch) by inserting / removing (attaching / removing) the corresponding paper feed unit 2. The output of each insertion / removal detection switch 25 is input to a main body control unit 7 described later, and the main body control unit 7 can detect insertion / removal of the paper feeding unit 2 (see FIG. 3).

  Next, the conveyance path 3 conveys the sheet and guides the sheet from the sheet feeding unit 2 to the discharge tray 31 through the intermediate transfer unit 5 and the fixing device 6. In the conveyance path 3, a plurality of conveyance roller pairs 32 (32 </ b> A to 32 </ b> D, denoted by symbols A, B, C, and D from above), guides, and conveyed paper are waiting in front of the intermediate transfer unit 5. In addition, a registration roller pair 33 and the like that are sent out at the same timing are provided. A discharge roller pair 34 that discharges the sheet toward the discharge tray 31 is also provided on the downstream side of the fixing device 6. A paper sensor 351 (for example, using an optical sensor) for detecting paper discharge is provided in the vicinity of the discharge roller pair 34.

  Further, the side cover 104 and the side cover 105 on the left side portion of the multi-function device 100 can be opened and closed as shown by the white arrow in FIG. 1 for paper removal processing when a jam (paper jam) occurs. It is. As shown in FIG. 1, an open / close detection switch 36 is provided to detect opening / closing of the side cover 104. An open / close detection switch 37 is provided to detect opening / closing of the side cover 105. The open / close detection switch 37 is switched ON / OFF by opening / closing (for example, an interlock switch). The output of the open / close detection switch 37 is input to a main body control unit 7 described later, and the main body control unit 7 can detect opening / closing of the side covers 104 and 105 (see FIG. 3).

  As shown in FIGS. 1 and 2, the multifunction peripheral 100 includes an image forming unit 4 as a part for forming a toner image based on image data. Specifically, the image forming unit 4 includes an exposure device 41, an image forming unit 42a that forms a black image, an image forming unit 42b that forms a yellow image, and an image forming unit 42c that forms a cyan image. The image forming unit 42 for four colors of the image forming unit 42d for forming a magenta image is provided.

  Here, the image forming units 42a to 42d will be described in detail with reference to FIGS. Each of the image forming units 42a to 42d has basically the same configuration except that the color of the toner image to be formed is different. Therefore, in the following description, the symbols a, b, c, and d are omitted unless otherwise described, and the configuration of the image forming unit 42 will be described.

  Each photosensitive drum 43 is rotatably supported, receives a driving force from a motor (not shown), rotates, and carries a toner image on the peripheral surface. Each photosensitive drum 43 is driven to rotate counterclockwise at a predetermined speed. Each charging device 44 charges the photosensitive drum 43 at a constant potential. Each charging device 44 may be one that charges each photosensitive drum 43 using a corona discharge type or a brush.

  An exposure device 41 below each image forming unit 42 is a laser unit that outputs laser light. Based on the color-separated image signal, laser light (illustrated by a broken line) that is an optical signal is applied to each photosensitive drum 43. Then, the photosensitive drum 43 after charging is scanned and exposed to form an electrostatic latent image. The exposure device 41 may be an array of LEDs. Each developing device 45 stores a developer containing toner (the image forming unit 42a has black, the image forming unit 42b has yellow, the image forming unit 42c has cyan, and the image forming unit 42d has magenta. Of developer). Each developing device 45 supplies toner to the photosensitive drum 43. As a result, the electrostatic latent image on the photosensitive drum 43 is developed. Each cleaning device 46 scrapes and removes dirt such as residual toner after transfer.

  Returning to FIG. The intermediate transfer unit 5 receives the primary transfer of the toner image from the photosensitive drum 43 and performs secondary transfer on the paper. The intermediate transfer unit 5 includes primary transfer rollers 51a to 51d, an intermediate transfer belt 52, a driving roller 53, driven rollers 54 to 56, a secondary transfer roller 57, a belt cleaning device 58, and the like. Each primary transfer roller 51 a to 51 d sandwiches an endless intermediate transfer belt 52 with each photosensitive drum 43.

  The intermediate transfer belt 52 is made of a dielectric resin or the like, is stretched around a driving roller 53 and driven rollers 54 to 56, and is rotated by a driving roller 53 connected to a driving mechanism (not shown) such as a motor. Orbit in the clockwise direction. The driving roller 53 and the secondary transfer roller 57 sandwich the intermediate transfer belt 52 to form a secondary transfer nip. In transferring the toner image, a predetermined voltage is applied to each of the primary transfer rollers 51a to 51d. The toner images (black, yellow, cyan, and magenta) formed by each image forming unit 42 are primarily transferred to the intermediate transfer belt 52 while being superimposed without any deviation. Then, when the superimposed toner images of the respective colors enter the secondary transfer nip, the paper also enters, and the toner image is secondarily transferred to the paper by the secondary transfer roller 57 to which a predetermined voltage is applied. . The belt cleaning device 58 removes and collects residual toner and the like on the intermediate transfer belt 52 after the secondary transfer.

  The fixing device 6 is arranged downstream of the intermediate transfer unit 5 in the paper transport direction, and heats and presses the secondly transferred toner image to fix it on the paper. The sheet after fixing is discharged to the discharge tray 31 and the image forming process is completed. Details of the fixing device 6 will be described later.

(Hardware configuration of MFP 100)
Next, based on FIG. 3, the hardware configuration of the multifunction peripheral 100 according to the embodiment of the present invention will be described. FIG. 3 is a block diagram illustrating an example of a hardware configuration of the multifunction peripheral 100 according to the embodiment of the present invention.

  As illustrated in FIG. 3, the multifunction peripheral 100 according to the present embodiment includes a main body control unit 7 (corresponding to a control unit). The main body control unit 7 controls each unit of the apparatus. For example, the main body control unit 7 includes a CPU 71, a time measuring unit 72, and other electronic circuits and elements. The main body control unit 7 is connected to the storage unit 73. The CPU 71 is a central processing unit, and controls and performs each part of the multifunction peripheral 100 based on a control program stored in the storage unit 73 and developed. The timer 72 measures various times necessary for control. The storage unit 73 is configured by a combination of nonvolatile and volatile storage devices such as ROM, RAM, flash ROM, and HDD. For example, the storage unit 73 stores various data such as control data in addition to the control program of the multifunction peripheral 100.

  The main body control unit 7 is divided into functions such as a main control unit that performs overall control and image processing, and an engine control unit that controls ON / OFF of a motor that rotates the fixing device 6 and various rotating bodies. There are cases where a plurality of types are provided, but in the present description and each figure, they are collectively described as the main body control unit 7.

  The main body control unit 7 is connected to the paper feeding unit 2, the conveyance path 3, the image forming unit 4, the intermediate transfer unit 5, the fixing device 6, and the like, and appropriately forms an image based on the control program and data in the storage unit 73. Control the operation of each part to be performed. In the present invention, the main body control unit 7 grasps the paper size accommodated in the paper feeding unit 2 based on the output of the paper size sensor 24, controls the mode switching, and controls the temperature sensor S (temperature detection body). Based on the output, the temperature of the heating unit is grasped and the power supplied is controlled to control the heating in the fixing device 6.

  The main body control unit 7 is connected to a computer 200 (personal computer or the like), which is a transmission source of image data to be printed, via a communication unit 74 (interface unit). For example, driver software for using the multifunction device 100 is installed in each computer 200. A plurality of computers 200 can be communicably connected to the multifunction device 100 via a network. In addition, the computer 200 can be directly connected to the communication unit 74 by a cable or the like. The communication unit 74 receives print data including print setting data such as image data to be printed and the size of paper to be used from the computer 200 (for example, written in PDL language). The user can make various settings on the computer 200 or the like, for example, the paper size to be used, the number of copies, the number of pages to be included in one sheet, and the like. The setting contents are included in the print data as setting data. Image data after image processing is performed on the image data in the print data received from the computer 200 is transmitted to the exposure device 41 of the image forming unit 4, and the exposure device 41 generates an electrostatic latent image on the photosensitive drum 43. Form.

  Further, a paper size sensor 24 in each paper feeding unit 2 is connected to the main body control unit 7 (for example, the CPU 71). Then, the main body control unit 7 recognizes the size of the paper stored in each paper feeding unit 2 based on the output voltage of the paper size sensor 24. Further, the operation panel 1 is connected to the main body control unit 7, and an input to the operation panel 1 for selecting a paper size to be printed by the user is transmitted to the main body control unit 7. In addition, the main body control unit 7 can grasp the paper used for printing based on the setting data in the print data from the computer 200. The main body control unit 7 checks the paper size accommodated in each paper feeding unit 2 and feeds paper from the paper feeding unit 2 containing the instructed size during printing. As described above, the multifunction peripheral 100 according to this embodiment can print on paper of various sizes. Further, a plurality of paper sensors 35 (351 to 357) are connected to the main body control unit 7. The main body control unit 7 can recognize the completion of printing for one page by detecting the discharge of the sheet from the discharge roller pair 34 based on the output of the sheet sensor 351.

(Configuration of Fixing Device 6)
Next, an example of the configuration of the fixing device 6 according to the embodiment of the present invention will be described with reference to FIG. 4A is a schematic cross-sectional view of an example of the fixing device 6 according to the embodiment of the present invention as viewed from the front, and FIG. 4B is a perspective view illustrating an example of the configuration around the heating roller 61.

  As shown in FIG. 4A, in the fixing device 6 of this embodiment, a heating roller 61 (corresponding to a heating unit), a fixing roller 62 (corresponding to a heating unit), and a sheet for fixing a toner image are contacted. A heating unit including a heating belt 63 (corresponding to a rotating body of the heating unit) as a rotating body, a coil 8, a core 9, an external core 91, a pressure roller 64, and the like are provided. The heating roller 61, the fixing roller 62, the heating belt 63, the core 9, and the pressure roller 64 are rotatably supported so that the axial directions are parallel.

  The heating roller 61 is heated by induction heating by the coil 8 for fixing, and is made of, for example, iron. The heating roller 61 has the axial direction in the paper surface depth direction (direction perpendicular to the paper conveyance direction, paper width direction) in FIG. Then, for example, a fixing roller 62 which is elastic and has a peripheral surface formed of a sponge-like material is provided to face the heating roller 61. A heating belt 63 is wound around the heating roller 61 and the fixing roller 62. The heating belt 63 has a function of transferring heat to the fixing roller 62. The heating belt 63 is a rotating body that is heated by induction heating by the coil 8 for fixing, and is endless with a thinly stretched metal (for example, nickel).

  A pressure roller 64 is provided to face the fixing roller 62. The pressure roller 64 is formed of, for example, a sponge-like material and is urged by an urging member 65 (for example, a spring) in the direction of the fixing roller 62 while the heating belt 63 is sandwiched between the fixing roller 62. As a result, the pressure roller 64 is in pressure contact with the heating belt 63 to form a fixing nip N.

  For example, the driving force of the fixing motor 66 (see FIG. 6) provided in the fixing device 6 is transmitted to the fixing roller 62, and the fixing roller 62 rotates. When the fixing roller 62 rotates, the heating belt 63 rotates, and the heating roller 61 also rotates. The pressure roller 64 also rotates in accordance with the rotation of the fixing roller 62. Then, when the paper on which the toner image is transferred enters the fixing nip N while rotating the fixing roller 62 and the like, and the paper is transported and passed, the toner image is heated and pressurized and fixed on the paper (paper transport direction). Is shown by a broken line).

  Next, a configuration for heating the heating belt 63 and the heating roller 61 will be described. As shown in FIG. 4A, the coil 8 and the core 9 are provided to face the peripheral surface of the heating roller 61 on the side opposite to the side on which the fixing roller 62 is provided. Then, as shown in FIGS. 4A and 4B, the coil 8 is opposed to the heating unit (the heating belt 63 and the like) and is wound around the axial direction of the rotating body (the heating belt 63). Warm the heated part by heating. Further, the coil 8 avoids the gap G between the heating roller 61 and the core 9, and is wound around the heating roller 61 along the axial direction of the heating roller 61 in a C shape when viewed from the circumferential direction. The core 9 is opposed to the heating unit including the heating roller 61 and the like, forms a magnetic path between the coil 8 and the heating unit, and the peripheral surface is covered with magnetic shielding plates 92A and 92B that shields magnetism, thereby heating the heating unit. In order to vary the heating width to be performed, the length in the axial direction covered by each magnetic shielding plate 92 differs by a plurality of levels depending on the circumferential position (see FIG. 5). The core 9 is parallel to the heating roller 61 in the axial direction. And as shown in FIG.4 (b), the coil 8 is comprised with one conducting wire, and the alternating voltage is applied to a terminal by using the both ends of a conducting wire as a terminal (details are mentioned later).

  When an alternating voltage is applied to the coil 8, a current flows through the coil 8, and a magnetic field is formed, for example, as shown by a two-dot chain line in FIGS. 4 (a) and 4 (b). The outer core 91 is made of, for example, ferrite, forms a magnetic path, and prevents diffusion of magnetic flux. Then, the magnetic flux passes through the heating belt 63 and the heating roller 61, and an eddy current is generated. The heating belt 63 and the heating roller 61 are warmed by the Joule heat generated by the generated eddy current (induction heating). During induction heating, the fixing roller 62 and the like are rotated to warm the heating roller 61 and the heating belt 63, and heat is conducted to the fixing roller 62 by the heating belt 63. Further, the heat is also transmitted to the pressure roller 64. In this way, the fixing device 6 is warmed. At the time of fixing or in the normal mode, the fixing roller 62 or the like is warmed to, for example, about 170 ° C. (fixing control temperature).

  The fixing device 6 of the present embodiment is provided with a plurality of temperature sensors S (corresponding to temperature detectors). Each temperature sensor S is provided in contact with the heating belt 63 in the vicinity of the paper entrance portion (a non-contact type may be used). The fixing device 6 of the present embodiment can change the heating width for heating the heating belt 63 and the like (the length in which the heating belt 63 and the heating roller 61 are heated in the axial direction) (details will be described later). Therefore, a plurality of devices are provided, one for measuring the temperature at the end of each heating width and the other for measuring the temperature of the central portion of the heating belt 63 in the axial direction. That is, a plurality of temperature sensors S are provided to detect the temperature of the heating unit in accordance with the heating width. Since the temperature sensor S is provided in parallel along the axial direction of the fixing roller 62, only one on the near side is shown in FIG. Each temperature sensor S may have the same configuration, for example, has a thermistor, and the output voltage changes depending on the temperature of the heating belt 63.

(Core 9 and magnetic shielding plates 92A and 92B)
Next, an example of the core 9 of the fixing device 6 according to the embodiment of the present invention will be described with reference to FIG. FIG. 5 is an explanatory diagram for explaining an example of the core 9 of the fixing device 6 according to the embodiment of the present invention.

  The multifunction peripheral 100 according to the present embodiment can print using paper of various sizes. In the multifunction peripheral 100 according to the present embodiment, the fixing device 6 or the like performs the central sheet passing so that the center axis of the sheet in the sheet conveyance direction coincides with the center in the width direction of the conveyance path. For example, assuming that a maximum of A3 size paper can be printed by the multifunction peripheral 100 of the present embodiment, the lengths in the axial direction of the heating roller 61, the fixing roller 62, the pressure roller 64, the heating belt 63, and the like are as follows. The size is larger than the short side (about 30 cm) of A3.

  When the printing of the paper is continuously performed, the heat is taken away at the portion in contact with the paper, so that the heating roller 61 and the heating belt 63 are heated so that the temperature of the heating belt 63 does not fall below the fixing control temperature. Must do so. However, for example, when continuously printing a paper having a width smaller than that of A3 paper such as A4 side or A6 (substantially equivalent to a postcard size), the heating roller 61 is heated with a heating width (heating width W4) that matches A3. If the operation is continued, heat is removed only at the central portion of the heating roller 61, the fixing roller 62, the heating belt 63, and the pressure roller 64, and heat is not removed at the end portion in the longitudinal direction (axial direction).

  As a result, the temperatures at the longitudinal ends of the heating roller 61, the fixing roller 62, the heating belt 63, and the pressure roller 64 continue to rise. If the temperature rises too much, problems such as heat damage of the heating belt 63 and the fixing roller 62 may occur. Therefore, magnetic shielding plates 92A and 92B are provided on the core 9 so that the heating width of the heating roller 61 and the heating belt 63 can be switched in a plurality of stages.

  Therefore, the configuration of the core 9 will be described with reference to FIG. First, the core 9 is a cylindrical or columnar member made of ferrite, for example. By using ferrite which is a ferromagnetic material, the magnetic flux of the coil 8 can be concentrated at the position facing the heating roller 61, and the magnetic flux can be efficiently linked to the heating belt 63 and the heating roller 61. In addition, ferrite has a large electrical resistance value, hardly causes eddy current loss, and can efficiently heat the heating belt 63 and the heating roller 61.

  As shown in the drawing on the left side of FIG. 5, in the fixing device 6 of the present embodiment, magnetic shielding plates 92 </ b> A and 92 </ b> B are provided (attached) to both ends of the peripheral surface of the core 9, respectively. In FIG. 5, for convenience, the magnetic shielding plates 92A and 92B are shaded, and the surface of the core 9 and the magnetic shielding plates 92A and 92B are shown separately. Further, since the functions of the magnetic shielding plates 92A and 92B are common, the symbols A and B are omitted in the following description unless otherwise specified.

  For example, each magnetic shielding plate 92 is formed of a conductor having a low magnetic permeability and a low resistance, such as a copper plate. When the magnetic flux penetrates each magnetic shielding plate 92, according to Lenz's law, a current flows through the conductor plate in a direction to cancel the magnetic flux, and the magnetic flux is interrupted. As shown in FIG. 5, each magnetic shielding plate 92 has a stepped shape, has a difference in the length in the axial direction covering the peripheral surface of the core 9, and allows the heating width of the heating roller 61 to be switched. .

  Next, description will be made based on the drawing on the right side of FIG. The drawing on the right side of FIG. 5 is a developed view in which the peripheral surface of the core 9 is developed. For example, when the area covered by each magnetic shielding plate 92 is the largest in the peripheral surface of the core 9 and the exposed portion is short in the axial direction of the heating belt 63 or the heating roller 61, the heating belt 63 is opposed to the heating belt 63. The heating width is the narrowest. In other words, the heating width becomes narrower as the portion of the long axial length covered by each magnetic shielding plate 92 is opposed to the heating belt 63.

  And in the core 9 of this embodiment, the length covered with each magnetic shielding board 92 has four steps. For example, the narrowest heating width (this heating width is defined as heating width W1) corresponds to the length of the short side (for example, about 10 cm) of a postcard or A6 paper. When the heating belt 63 is opposed to the heating belt 63, the heating belt 63 is used when conveying the paper with the short side direction of the postcard or A6 paper aligned with the axial direction of the heating belt 63. Only the area where the sheet 63 is in contact with the sheet (sheet passing area) can be warmed. The heating width that is one step wider than the heating width W1 (this heating width is referred to as the heating width W2) corresponds to, for example, the length of the short side of the A4 size paper (for example, about 21 cm). When the heating width W2 is opposed to the heating belt 63, the short side direction of the A4 paper in the heating belt 63 and the axial direction of the heating belt 63 coincide with each other (A4 side) or A5. When the paper is transported by making the long side direction of the paper coincide with the axial direction of the heating belt 63 (A5 length), only the area where the heating belt 63 and the paper are in contact (paper passing area) can be warmed.

  A heating width that is one step wider than the heating width W2 (this heating width is referred to as a heating width W3) corresponds to, for example, the length of the short side of a B4 size sheet (for example, about 26 cm). When the heating belt 63 is opposed to the heating belt 63, the short belt direction of the B4 paper and the axial direction of the heating belt 63 in the heating belt 63 coincide with each other (B4 side) or B5. When the paper is transported by aligning the long side direction of the paper and the axial direction of the heating belt 63 (vertical B5), only the area where the heating belt 63 and the paper are in contact (paper passing area) can be warmed. The widest heating width (this heating width is referred to as heating width W4) corresponds to the length size (for example, about 30 cm) of the short side of the A3 size paper. When the heating width W4 is opposed to the heating belt 63, the paper is conveyed with the short side direction of the A3 paper and the axial direction of the heating belt 63 of the heating belt 63 aligned (A3 side) or A4. When the paper is transported by making the long side direction of the paper coincide with the axial direction of the heating belt 63 (A4 length), only the area where the heating belt 63 and the paper are in contact (paper passing area) can be warmed. Then, in accordance with the paper size selected by the paper size sensor 24 or the operation panel 1, the core 9 is rotated by a core motor 93 (see FIG. 6, corresponding to a variable mechanism, a rotating unit) described later, and the heating width is switched.

(Hardware configuration related to heating control in the fixing device 6)
Next, an example of a hardware configuration related to heating control in the fixing device 6 according to the embodiment of the present invention will be described with reference to FIG. FIG. 6 is a block diagram illustrating an example of a hardware configuration related to heating control in the fixing device 6 according to the embodiment of the present invention.

  As shown in FIG. 6, the fixing device 6 of the present embodiment is provided with a fixing control unit 60 that performs heating control of the fixing device 6. The fixing control unit 60 performs heating control in response to an instruction from the main body control unit 7. For example, the fixing control unit 60 includes a controller 67 as a control element. The controller 67 performs actual heating control of the fixing device 6. Further, the fixing controller 60 rotates a fixing motor 66 that rotates the heating belt 63, the heating roller 61, the fixing roller 62, and the like at a predetermined speed during printing.

  In addition, the fixing control unit 60 is provided with a PWM circuit 69 that applies an alternating current to the coil 8 based on, for example, power supplied from a power supply device 78 provided in the multifunction peripheral 100. The controller 67 of the fixing controller 60 is supplied with a heating ON / OFF instruction signal for instructing ON / OFF of heating from the main body controller 7. The controller 67 causes the PWM circuit 69 to supply power to the coil 8 when instructing heating ON.

  Further, the main body control unit 7 gives a power instruction to the controller 67 to be put into the coil 8 to be consumed (converted into heat). On the other hand, the controller 67 detects the electric power supplied from the PWM circuit 69 to the coil 8 and consumed to warm the heating belt 63 and the heating roller 61. Then, the controller 67 operates the PWM circuit 69 so that the instruction from the main body control unit 7 matches the detected power. For example, the PWM circuit 69 controls the power consumed by heating by changing the frequency of the current flowing through the coil 8 and controlling the amount of current flowing through the coil 8.

  For example, the main body control unit 7 controls the core motor 93 with respect to the rotation angle of the core 9. The core motor 93 rotates the core 9. Thereby, the core 9 rotates and the heating width is switched. That is, the fixing device 6 includes a core motor 93 as a variable mechanism that varies the heating width in the axial direction of the rotating body (such as the heating belt 63). By narrowing the heating width, less energy is converted into heat, so less power is consumed by the coil 8. In addition, a temperature sensor S1 that detects the temperature of the central portion of the heating belt 63, a temperature sensor S2 that detects the temperature of the end of the heating width W2 (the end in the axial direction of the heating belt 63, and so on), and the heating width The output voltage of the temperature sensor S3 that detects the temperature of the end portion of W3 and the temperature sensor S4 that detects the temperature of the end portion of the heating width W4 is input to the CPU 71 of the main body control unit 7. That is, a plurality of temperature sensors S (temperature detection bodies) are provided to detect the temperature of the heating unit in accordance with the heating width. For example, the storage unit 73 stores a data table in which the temperature with respect to the output voltage of each temperature sensor S and the resistance value of the thermistor are determined. Based on this data table, the main body control unit 7 can detect the temperature of each part of the heating belt 63.

(Normal mode, low power mode, sleep mode)
Next, a normal mode, a low power mode, and a sleep mode in the multifunction peripheral 100 according to the embodiment of the present invention will be described with reference to FIG.

  First, the MFP 100 according to the present embodiment includes a normal mode, a low power mode in which power consumption supplied to the fixing device 6 is lower than that in the normal mode, and a sleep in which power consumption supplied to the fixing device 6 is lower than that in the low power mode. Has a mode. For example, in the normal mode, the main body control unit 7 and the storage unit 73, the paper feeding unit 2, the conveyance path 3, the image forming unit 4, the intermediate transfer unit 5, the fixing device 6, the communication unit 74, etc. Power is supplied to each component. For example, in the fixing device 6, the temperature of the heating belt 63 and the like is maintained at a fixing control temperature (for example, about 170 ° C.). In this way, for example, in the normal mode, the multifunction peripheral 100 is maintained in a state in which printing can be immediately performed.

  For example, the low power mode is a mode in which power consumed is reduced as compared with the normal mode. In the low power mode, for example, when the main body control unit 7 detects that a certain period of time (for example, about 5 to 10 minutes, which can be set with the operation panel 1) has passed without the multifunction device 100 being used (for example, a timing unit). 72 is timed), the mode of the multifunction device 100 shifts from the normal mode to the low power mode. In the low power mode, the main body control unit 7 and the storage unit 73, the paper feeding unit 2, the conveyance path 3, the image forming unit 4, the intermediate transfer unit 5, the fixing device 6, the communication unit 74, etc. Power is supplied to the configuration. However, in the fixing device 6, the temperature of the heating belt 63 or the like is maintained at a low power mode maintaining temperature (for example, about 120 to 150 ° C.) that is equal to or lower than the fixing control temperature. Thus, for example, in the low power mode, the temperature of the heating belt 63 and the like is maintained at a lower temperature than in the normal mode, so that power consumption is lower than in the normal mode.

  In addition, the sleep mode is a mode that further reduces power consumption as compared with the normal mode and the low power mode. In the low power mode, for example, when the main body control unit 7 detects that a certain time (for example, 30 to 240 minutes, which can be set by the operation panel 1) has passed without the multifunction device 100 being used (for example, the time measuring unit 72). The mode of the MFP 100 shifts from the normal mode or the low power mode to the sleep mode. At this time, power supply from the power supply device 78 to the main body control unit 7, the image forming unit 4, the intermediate transfer unit 5, the fixing device 6 and the like is stopped. Thereby, the power consumption of the multifunction device 100 can be reduced.

  As described above, the voltage to be generated by the power supply device 78 and the amount of power to be supplied are different in the normal mode, the low power mode, and the sleep mode. Therefore, the power supply device 78 includes a normal mode control unit 79A that controls the operation of the power supply device 78 in the normal mode, a low power mode control unit 79B that controls the operation of the power supply device 78 in the low power mode, and a sleep mode. A sleep mode control unit 79C for controlling the operation of the power supply device 78 is provided. For example, when shifting to the low power mode, the main body control unit 7 gives an instruction to drive the power supply device 78 to the power supply device 78 using the low power mode control unit 79B. For example, when shifting to the sleep mode, the main body control unit 7 gives the power supply device 78 an instruction to drive the power supply device 78 using the sleep mode control unit 79 </ b> C toward the power supply device 78.

  That is, the main body control unit 7 controls the heating in the fixing device 6 and maintains the temperature of the heating unit at the fixing control temperature necessary for fixing the toner image in the normal mode, and in the low power mode, the heating unit is higher than the normal mode. In the sleep mode, heating to the heating unit is stopped.

  When a return factor to the normal mode occurs, such as when print data is transmitted from the external computer 200 in the low power mode or the sleep mode, the multifunction peripheral 100 changes from the low power mode or the sleep mode to the normal mode ( Return). In the multi-function device 100 of the present embodiment, for example, when there is an instruction or operation to the multi-function device 100 as described below, it is assumed that a factor for returning from the low power mode or the sleep mode to the normal mode has occurred. For example, for receiving print data from an external computer 200, copying, scanning, etc., input to the operation panel 1, loading / unloading of the paper feed unit 2 (detected by the insertion / removal detection switch 25 for confirming change of the paper size, etc.) ) Opening / closing of the side covers 104 and 105 (detected by the opening / closing detection switch 37) is a return factor.

  Here, in the MFP 100 according to the present embodiment, power supply to the main body control unit 7 is stopped in the sleep mode. For this reason, the main body control unit 7 is not driven, recognizes the occurrence of a return factor, and cannot give instructions to each unit such as the power supply device 78 of the multifunction peripheral 100. Therefore, as shown in FIG. 3, for example, the communication unit 74 includes a return factor monitoring unit 741 that monitors the occurrence of a return factor from the sleep mode to the normal mode. The return factor monitoring unit 741 is connected to the operation panel 1, the insertion / removal detection switch 25, the open / close detection switch 37, and the like. With these connections, the return factor monitoring unit 741 can recognize the occurrence of the return factor.

  If a return factor occurs and the main power control unit 7 shifts from the low power mode to the normal mode, the main body control unit 7 instructs the power supply device 78 to drive the power supply device 78 using the normal mode control unit 79A. To give. Thereby, warm-up for heating the heating belt 63 and the like in the fixing device 6 and the like to the fixing control temperature is started.

  When a return factor is generated and the sleep mode is shifted to the normal mode, the return factor monitoring unit 741 instructs the power supply device 78 to drive the power supply device 78 using the normal mode control unit 79A. To give. As a result, power supply to the main body control unit 7 and the fixing device 6 is resumed, and the multifunction device 100 can be used, so that the heating belt 63 and the like in the fixing device 6 and the like are warmed up to the fixing control temperature. Be started.

(Relationship between paper size and return time from sleep mode)
Next, the time until the warm-up is completed when the MFP 100 according to the embodiment of the present invention returns from the sleep mode to the normal mode will be described with reference to FIG. FIG. 7 shows an example of the time from the start of warm-up until the temperature of the heating belt 63 reaches the fixing control temperature when the MFP 100 according to the embodiment of the present invention returns from the sleep mode to the normal mode. It is a graph to show.

  First, the X-axis direction in the graph shown in FIG. 7 indicates the time required from the start of warm-up until the temperature of the heating belt 63 reaches the fixing control temperature when returning from the sleep mode to the normal mode (hereinafter, “ The length of "recovery time"). And the Y-axis direction in the graph shown in FIG. 7 shows the temperature of the paper passing area in the heating belt 63 or the like. A graph line G1 indicated by a solid line in FIG. 7 shows an example of a temperature rise of the heating belt 63 when the heating belt 63 is heated with the heating width W4 (A3 horizontal, A4 vertical). In addition, a graph line G2 indicated by a two-dot chain line in FIG. 7 shows an example of a temperature rise of the heating belt 63 when the heating belt 63 is heated with the heating width W2 (A4 horizontal, A5 vertical).

  As shown by the graph line G1, when the heating belt 63, the heating roller 61, and the like are heated with the heating width W4, about 45 seconds after the start of return from the sleep mode to the normal mode, The temperature of the paper passing area reaches 170 ° C. On the other hand, as shown by the graph line G2, when the heating belt 63, the heating roller 61, etc. are heated with the heating width W2, the heating belt 63, etc., after about 30 seconds from the start of return from the sleep mode to the normal mode. In this case, the temperature of the sheet passing area reaches 170 ° C. (fixing control temperature).

  Thus, when the heating width is narrower than when the heating width is wide, the temperature increase rate of the heating belt 63, the heating roller 61, the fixing roller 62, and the like is faster. For example, the maximum power that can be input to the fixing device 6 has an upper limit and is constant regardless of whether the heating width is wide or narrow. However, the maximum power is input per unit area of the heating belt 63 or the like as compared with the case where the heating width is narrow. Electric power can be increased. For this reason, it is considered that the heating of the heating belt 63 and the like is faster when the heating width is narrower than when the heating width is wide.

  On the other hand, in the MFP 100 according to the present embodiment, when returning from the low power mode to the normal mode with the maximum heating width (heating width W4), the process is completed from the start of warm-up to set the temperature of the heating belt 63 and the like to the fixing control temperature. It takes about 30 seconds. Therefore, when only paper (A4 horizontal, A5 vertical, A6, postcard, etc.) of a size corresponding to a heating width (W2, W1) narrower than the maximum heating width (heating width W4) is accommodated in the paper feeding unit 2. , Even if going directly to the sleep mode without going through the low power mode, the recovery time required to return to the normal mode is the shortest return time to the normal mode within the maximum heating width (return from the low power mode to the normal mode) ).

  In the MFP 100 according to the present embodiment, when the heating width for B4 landscape paper (heating width W3) is returned from the sleep mode to the normal mode, the temperature of the heating belt 63 and the like is allowed to reach the fixing control temperature. The time from the start to the completion is approximately 30 seconds to 45 seconds (for example, approximately 37, 38 seconds). Therefore, the recovery time required for returning from the sleep mode to the normal mode while heating with the heating width W3 is longer than the shortest normal mode return time (returning from the low power mode to the normal mode) in the maximum heating width. Become.

  Therefore, in the MFP 100 according to the present embodiment, when only a sheet having a size corresponding to a heating width (W2, W1) narrower than the maximum heating width (heating width W4) is accommodated in the sheet feeding unit 2, low power is required. It is possible to make a setting that allows the transition to the sleep mode without going through the mode.

(Mode transition setting)
Next, with reference to FIG. 8, an example of setting of transition of each mode in the multifunction peripheral 100 according to the embodiment of the present invention will be described. FIG. 8 is an explanatory diagram illustrating an example of a setting screen on the liquid crystal display unit 12 of the operation panel 1 of the multifunction peripheral 100 according to the embodiment of the present invention.

  The setting screen shown in FIG. 8 can be reached by pressing a key displayed on the operation panel 1 or the liquid crystal display unit 12. And on the setting screen shown in FIG. 8, the setting regarding the shift to the low power mode and the sleep mode can be performed.

  In the low power mode setting area F1 in which the setting relating to the low power mode is performed, it is possible to set how many minutes have passed since the multifunction device 100 was used last and the transition to the low power mode is made. And the low power mode transition time display column B1 which displays the time (setting value) until the present low power mode transition is provided. And the user can increase / decrease the time until it transfers to low power mode by pressing down the plus key K1 or the minus key K2.

  Further, in the low power mode setting area F1, whether or not to shift to the sleep mode without going through the low power mode is set when the paper stored in the paper feeding unit 2 is smaller than the size corresponding to the maximum heating width W4. can do. Therefore, a Yes key K3 and a No key K4 are arranged. In FIG. 8, the Yes key K3 is selected (black and white inversion state), and the setting is made to allow the transition to the sleep mode without going through the low power mode.

  Further, in the low power mode setting area F1, the time required for heating to the maximum heating width (corresponding to A3 paper) to bring the paper passing area to the fixing control temperature when returning from the low power mode to the normal mode is set. Only when a sheet whose size is shorter than the reference time when the return time for setting the sheet passing area to the fixing control temperature is stored in the sheet feeding unit 2 when the reference time is set and the normal mode is returned from the sleep mode. It is possible to set whether or not to shift to the sleep mode without going through the low power mode.

  That is, the multi-function device 100 includes a setting input unit (operation panel 1) that receives a setting input for shifting to the sleep mode without going through the low power mode or to shift to the sleep mode through the low power mode. Therefore, a Yes key K5 and a No key K6 are arranged. In FIG. 8, only when the Yes key K5 is selected (black-and-white inversion state) and a sheet whose recovery time from the sleep mode to the normal mode is shorter than the reference time is accommodated in each paper feed unit 2, It is set to allow the transition to the sleep mode without going through the power mode.

  For example, in the MFP 100 of the present embodiment, as described above, when heating with the heating width W3 (corresponding to the side of B4, etc.) and returning from the sleep mode to the normal mode, the return time is 30 seconds or more (for example, 37 seconds). On the other hand, when heating with the heating width W4 (corresponding to the side of A3) and returning from the low power mode to the normal mode, the time required to bring the temperature of the heating belt 63 and the like to the fixing control temperature is the reference time. Then, the return time from the sleep mode to the normal mode in the heating width W3 exceeds the reference time. Therefore, when heating with the heating width W3 and returning from the sleep mode to the normal mode, the user is long as viewed from the reference.

  Therefore, only when a sheet whose recovery time from the sleep mode to the normal mode is shorter than the reference time is accommodated in the paper feed unit 2 (size of A4 horizontal or smaller), the mode shifts to the sleep mode without going through the low power mode. It is possible to set to allow As a result, the low power mode is skipped and the mode is changed to the sleep mode only when sheets of a size whose return time from the sleep mode to the normal mode does not fall below a certain standard are stored in the paper feed unit 2. The As described above, when a sheet in which the return time from the sleep mode to the normal mode is longer than the reference is stored in the paper feeding unit 2, the normal mode is not switched to the sleep mode by skipping the low power mode, Prioritize user convenience.

  That is, when the main body control unit 7 returns from the sleep mode using the time to reach the fixing control temperature when returning from the low power mode to the normal mode while heating with the maximum heating width, When only the paper having a size shorter than the time required for the heating unit to reach the fixing control temperature required for fixing the toner image is stored in the paper feeding unit 2, the low power mode is not used. Switch to sleep mode.

  Furthermore, in the sleep mode setting area F2 where settings relating to the sleep mode are performed, it is possible to set how many minutes have elapsed since the multifunction device 100 was last used before being shifted to the sleep mode. And the sleep mode transition time display column B2 which displays the time (setting value) until transition to the current sleep mode is provided. The user can increase or decrease the time until the sleep mode is entered by pressing the plus key K7 or the minus key K8.

(Mode transition and heating control)
Next, an example of mode transition in the MFP 100 and heating control in the fixing device 6 according to the embodiment of the present invention will be described with reference to FIG. FIG. 9 is a flowchart illustrating an example of mode transition in the multifunction peripheral 100 and heating control in the fixing device 6 according to the embodiment of the present invention.

  First, the start of FIG. 9 is a time point after the main power supply of the multifunction peripheral 100 is turned on. When the main power of the multi-function device 100 is turned on, the main body control unit 7 starts driving. At this time, the mode of the multi-function device 100 is the normal mode (step # 1). Next, the main body control unit 7 confirms the output of each paper size sensor 24 and confirms the paper size accommodated in the paper feeding unit 2 (step # 2). Then, the main body control unit 7 confirms the heating width necessary for warming the sheet passing area of the heating belt 63 and the like for each size of sheet (step # 3). Then, the main body control unit 7 controls the core motor 93 to rotate the core 9 as necessary, and starts heating with the widest heating width among the necessary heating widths (step # 4).

  That is, the fixing device 6 is opposed to the heating unit (the heating belt 63, the heating roller 61, the fixing roller 62, etc.), is wound around the axial direction of the rotating body, and the coil 8 warms the heating unit by induction heating. The magnetic shield plate is opposed to the heating portion, forms a magnetic path between the coil 8 and the heating portion, the peripheral surface is covered with the magnetic shielding plate 92, and the heating width for heating the heating portion is varied. And a core 9 that is covered by 92 in different lengths in the axial direction, and has a rotating part that rotates the core 9 as a variable mechanism (core motor 93). The main body control part 7 controls the rotating part. The heating width in the heating unit is controlled by controlling the rotation angle of the core 9.

  For example, if A3 landscape paper is stored in the paper feeding unit 2, the heating width W4 is selected, and the heating belt 63 and the like are heated with the heating width W4. For example, if the largest sheet among the sheets stored in the sheet feeding unit 2 is A4 landscape size, the heating width W2 is selected, and the heating belt 63 and the like are heated with the heating width W2. Further, for example, if the paper accommodated in the paper feeding unit 2 is only a postcard, the heating width W1 is selected, and the heating belt 63 and the like are heated with the heating width W1.

  Then, the main body control unit 7 confirms the output of each temperature sensor S and confirms whether the temperature of the heated part has reached the fixing control temperature (step # 5). If the fixing control temperature has not been reached (No in step # 5), the process returns to step # 4. On the other hand, if the fixing control temperature is reached, the main body control unit 7 confirms the output of the temperature sensor S, causes the fixing control unit 60 to intermittently turn on the coil 8, and heats the heating belt 63 and the like. The remaining portion (paper passing area) is maintained at the fixing control temperature (step # 6).

  Next, the main body control unit 7 uses, for example, the time measuring unit 72 to check whether the low power mode transition time for shifting to the low power mode has elapsed without using the multifunction peripheral 100 (step # 7). If the MFP 100 is not used and the low power mode transition time has not elapsed (No in step # 7), the process returns to step # 6.

  On the other hand, if the MFP 100 has not been used and the low power mode transition time has elapsed (Yes in step # 7), the main body control unit 7 may transition to the sleep mode without going through the low power mode ( Whether or not the low power mode can be skipped is confirmed (step # 8). At this time, the main body control unit 7 confirms setting data (for example, stored in the storage unit 73) set for the low power mode and the sleep mode for the operation panel 1 illustrated in FIG. 8. In addition, the main body control unit 7 confirms whether or not only the paper smaller than the paper corresponding to the maximum heating width (heating width W4) is stored in the storage paper of the paper feeding unit 2. Further, the main body control unit 7 confirms whether or not a sheet whose recovery time from the sleep mode to the normal mode is longer than the reference is stored in the sheet feeding unit 2.

  If the low power mode is not skipped (No in step # 8), the main body control unit 7 shifts the multifunction peripheral 100 to the low power mode (step # 9). At the temperature at which the output of the temperature sensor S is confirmed, the fixing control unit 60 intermittently turns on the power to the coil 8, and the heated part (paper passing area) such as the heating belt 63 is maintained in the low power mode. Maintain (step # 10).

  Then, the main body control unit 7 checks whether or not a factor for returning from the low power mode to the normal mode, such as input of print data or input to the operation panel 1, has occurred (step # 11). If a return factor has occurred (Yes in step # 11), the process returns to step # 1. On the other hand, if no return factor has occurred (No in step # 11), the main body control unit 7 uses the time measuring unit 72 or the like, for example, because the MFP 100 has not been used and the sleep mode transition time has elapsed. It is confirmed whether or not the mode can be shifted to the sleep mode (step # 12). If it should not shift to the sleep mode (No in Step # 12), the process proceeds to Step # 10.

  When it is acceptable to enter the sleep mode without going through the low power mode (Yes in step # 8), or when the sleep mode may be entered because the sleep mode transition time has elapsed (Yes in step # 12), the main body control Unit 7 shifts to the sleep mode (step # 13). Then, the main body control unit 7 gives an instruction to the power supply device 78 to drive the sleep mode control unit 79C, and the power supply to the fixing device 6 and the like is stopped (step # 14). Then, when power supply to the main body control unit 7 is stopped, the return factor monitoring unit 741 confirms the occurrence of the return factor instead of the main body control unit 7 (step # 15).

  If no return factor has occurred (No in step # 15), the process returns to step # 14. On the other hand, if a predetermined return factor occurs, the return factor monitoring unit 741 gives an instruction to the power supply device 78 to drive the normal mode control unit 79A and resume power supply to the main body control unit 7, the fixing device 6 and the like. (Step # 16). Thereafter, the process returns to step # 1.

  When returning to step # 1, if the sheet accommodated in the sheet feeding unit 2 is only smaller than the size corresponding to the maximum heating width (for example, A4 horizontal or less), the maximum heating is performed. The heating belt 63 is heated with a heating width smaller than the width. That is, when only paper corresponding to a heating width smaller than the maximum heating width is accommodated in the paper feeding unit 2, the main body control unit 7 shifts to the sleep mode without going through the low power mode, and from the sleep mode to the normal mode. When returning to the mode, the variable mechanism (core motor 93) is controlled to bring the heating unit to a fixing control temperature necessary for fixing the toner image with a heating width corresponding to the size of the paper stored in the paper feeding unit 2. Let it heat.

  In this way, when only the paper corresponding to the heating width narrower than the maximum heating width is accommodated in the paper feeding unit 2, the mode is shifted to the sleep mode without going through the low power mode. Can be eliminated. Moreover, when returning to the normal mode, the heating unit (heating belt 63, heating roller 61, etc.) is set to a fixing control temperature necessary for fixing the toner image with a heating width narrower than the maximum heating width corresponding to the paper size. Therefore, the heating unit can be quickly warmed to the fixing control temperature while eliminating unnecessary power consumption. Thus, while achieving power saving, warm-up when returning from the sleep mode to the normal mode does not take a long time, and the convenience for the user is not impaired.

  Further, it includes a core 9 that is covered by the magnetic shielding plate 92 in a plurality of stages in the axial direction depending on the position in the circumferential direction, and has a rotating part (core motor 93) that rotates the core 9 as a variable mechanism, and a control part (main body) Since the control unit 7) controls the rotation part to control the rotation angle of the core 9, the heating width can be adjusted. In this case, the heating area is narrower when the heating width is narrower than when heating at the maximum heating width, and the portion to be heated is smaller than the electric power (for example, the allowable maximum electric power) input to the fixing device 6. That's it. For example, the density of power that can be input per unit area can be increased when the heating width is narrower than at the maximum heating width. Accordingly, the temperature increase in the sheet passing area to the fixing control temperature can be accelerated when the heating width is narrower than when heating at the maximum heating width.

  In addition, it is possible to set in the setting input unit (operation panel 1) whether to shift to the sleep mode without going through the low power mode or to shift to the sleep mode through the low power mode, so that the intention of the user is reflected. Can be controlled. For example, a user who places importance on the power saving effect may make a setting for shifting to the sleep mode without going through the low power mode. On the other hand, a user who wants to shorten the return time for returning from a mode other than the normal mode and give priority to convenience may set to shift to the sleep mode via the low power mode. In addition, there is a certain difference in power consumption depending on the normal mode, the low power mode, and the sleep mode. By shifting to the sleep mode without going through the low power mode, it is possible to eliminate waste of power that is consumed reliably.

  Also, the recovery time when returning from the low power mode to the normal mode with the maximum heating width is used as the reference time, and the low power mode is set only when the recovery time when returning from the sleep mode to the normal mode is shorter than this reference time. Transition to normal mode without intervention. This avoids the transition from the normal mode to the sleep mode without going through the low power mode for the paper whose size is long in the return time when returning from the sleep mode to the normal mode under a certain standard. be able to. User convenience is ensured.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention is applicable to an image forming apparatus having a fixing device.

DESCRIPTION OF SYMBOLS 1 Operation panel 2 (2A, 2B, 2C, 2D) Paper feeding part 24 Paper size sensor 4 Image forming part 6 Fixing device 61 Heating roller (heating part)
62 Fixing roller (heating unit) 63 Heating belt (rotating body, heating unit)
7 Main body control unit (control unit) 73 Storage unit 74 Communication unit 8 Coil 8
9 Core 92 (92A, 92B) Magnetic shielding plate 93 Core motor (variable mechanism, rotating part) 100 Multifunction machine (image forming apparatus)
S (S1, S2, S3, S4) Temperature sensor (temperature detector)
W (W1, W2, W3, W4) Heating width

Claims (5)

A paper feed unit that stores paper used for printing, an image forming unit that forms a toner image, a heating unit that includes a rotating body that contacts the paper for fixing the toner image, and a variable heating width in the axial direction of the rotating body A fixing device having a variable mechanism, a normal mode, a low power mode that reduces power consumption supplied to the fixing device than the normal mode, and a sleep that reduces power consumption supplied to the fixing device than the low power mode In an image forming apparatus having a mode,
In order to detect the temperature of the heating unit according to the heating width, a plurality of temperature detectors provided,
A paper size sensor for detecting the paper size stored in the paper feed unit;
Based on the output of the paper size sensor, the size of the paper stored in the paper feeding unit is grasped, the mode switching is controlled, and the temperature of the heating unit is grasped based on the output of the temperature detection body. A controller for controlling the heating of
When only a sheet corresponding to a heating width smaller than the maximum heating width is stored in the sheet feeding unit, the control unit shifts to the sleep mode without passing through the low power mode, and When returning to the normal mode, the variable mechanism is controlled to heat the heating unit to a fixing control temperature necessary for fixing the toner image with a heating width corresponding to the size of the paper stored in the paper feeding unit. An image forming apparatus. The fixing device is opposed to the heating unit, is wound around the axial direction of the rotating body, and heats the heating unit by induction heating, and is opposed to the heating unit, the coil and the heating unit, In order to change the heating width for heating the heating unit, the length in the axial direction covered by the magnetic shielding plate is a plurality of stages depending on the position in the circumferential direction. Including different cores,
A rotating unit that rotates the core as the variable mechanism;
The image forming apparatus according to claim 1, wherein the control unit controls a heating width in the heating unit by controlling the rotation angle of the core by controlling the rotating unit.   3. A setting input unit that accepts a setting input for shifting to the sleep mode without passing through the low power mode or to shift to the sleep mode via the low power mode. The image forming apparatus described in 1.   The control unit controls heating in the fixing device, and maintains the temperature of the heating unit at a fixing control temperature necessary for fixing a toner image in the normal mode, and in the low power mode than in the normal mode. 4. The image forming apparatus according to claim 1, wherein the temperature of the heating unit is maintained in a low state and heating of the heating unit is stopped in the sleep mode. 5.   When the control unit returns from the sleep mode, using the time to reach the fixing control temperature when returning from the low power mode to the normal mode while heating with the maximum heating width, When only paper of a size smaller than the time required for the heating unit to reach the fixing control temperature required for fixing the toner image than the reference time is stored in the paper feeding unit, the low power 5. The image forming apparatus according to claim 1, wherein the image forming apparatus shifts to the sleep mode without going through a mode.

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