JP6516800B2 - Image forming device - Google Patents

Description

  The present invention relates to an image forming apparatus capable of forming an image on a recording material such as, for example, a copying machine, a printer, or a facsimile employing an electrophotographic method.

  An image forming apparatus using a transfer type electrophotographic method develops a latent image formed on a photosensitive drum as an image carrier with toner (developer), and the toner image (visible image) is used as a recording material (a visible image). Sheet: Hereinafter, the sheet is transferred to the sheet or sheet using electrostatic force and pressure. Then, the transferred toner image is fixed by heat and pressure by a fixing device as an image heating device, whereby an image is recorded on a sheet material.

  As a fixing device, the elastic pressure roller is pressed and pressed by a pressure lever in which a pressure spring is stretched over a fixing roller having a heater inside to form a fixing nip portion, and a toner image is carried in the nip portion Conventionally, a roller fixing method in which a sheet being conveyed is nipped and conveyed to be fixed is adopted.

  In addition, the pressure lever is operated to retract the pressure roller from the fixing roller and release the pressure in order to suppress plastic deformation or the like of the elastic layer of the pressure roller by maintaining the pressure contact state between the fixing roller and the pressure roller. A pressure system having a pressure release mechanism is used. In recent years, transition of the image forming apparatus main body to the low power mode is performed at the time of non-image formation of the image forming apparatus for the purpose of energy saving in consideration of the environment.

  In the transition to the low power mode, the pressure release operation of the fixing device is also performed. In order to return to the image forming state from the low power mode, with the speeding up of the recent return, it is required to make the standby state faster, and the pressure operation of the fixing device is also performed at the time of return. For example, as described in Patent Document 1, an apparatus has been proposed in which a low power mode is provided in a multifunction peripheral and the entire apparatus including the fixing device always starts up when returning from the low power mode.

  When the transition to the low power mode increases, the start-up operation at the time of return also increases, and as a result, the number of pressure release operations increases, which affects the life of the fixing device. It is used.

  In addition, as a proposal to reduce the number of pressure switching operations, as described in Patent Document 2, when the paper jam (JAM) occurs, the length of the paper nipped by the fixing nip portion is calculated, and It is determined based on whether or not the pressure reduction operation (pressure release operation) is to be performed. Thus, an apparatus has been proposed that reduces the number of pressure reducing operations (pressure release operations).

Japanese Patent Application Laid-Open No. 10-308833 JP, 2016-18128, A

  By the way, as described in Patent Document 1, when the fixing device is started at the same time as returning from the low power mode, the case where the fixing device does not need to be started up is wasted in some cases. There is a fear. Further, as described in Patent Document 2, although the number of pressure reducing operations (pressurizing releasing operations) is reduced, this is only at the occurrence of jamming, and there is no disclosure about the return from the low power mode. . Therefore, there is a risk that an unnecessary pressure contact operation may be performed when returning from the low power mode. As a result, the number of pressure contact operations and pressure release operations unnecessarily increases, which may lead to deterioration of the pressure mechanism and the pressure release mechanism.

  The present invention has been proposed in view of the above-mentioned prior art. An object of the present invention is to provide an image forming apparatus capable of reducing the number of useless pressing operations in a fixing device.

A representative configuration of an image forming apparatus according to the present invention for achieving the above object is
An image forming apparatus for forming an image;
With a manual feed tray,
A detection unit that detects whether a sheet is placed on the manual feed tray;
An image forming unit for forming an image on a sheet supplied from the manual feed tray;
An endless belt for heating an image formed on the sheet at the nip portion by pre-Symbol image forming unit,
A heater for heating the endless belt;
A driving rotating body which cooperates with the endless belt to form the nip portion and which rotationally drives the endless belt ;
A pressure mechanism for pressing the endless belt toward the drive rotating body;
A first position at which the nip portion is formed by the endless belt and the drive rotating body;
The pressing mechanism can take a second position in which a force applied between the endless belt and the drive rotating body is smaller by the pressing mechanism than when the pressing mechanism is positioned at the first position. A moving mechanism for moving the pressure mechanism, and
A control unit that controls the operation of the movement mechanism;
A reception unit that receives an input of an instruction regarding an image forming operation for forming an image on a sheet by the image forming unit;
The image forming apparatus selectively selects one of a plurality of modes including a first mode in which the control unit is in a resting state, and a second mode in which power is supplied to the control unit. Is viable and
When the first mode is being executed and the pressing mechanism is in the second position, the detection unit detects that the sheet has been placed on the manual feed tray. The image forming apparatus shifts the mode to be executed to the second mode, and the receiving unit receives an input of a predetermined instruction regarding the image forming operation while the second mode is being executed, The control unit controls the moving mechanism such that the pressing mechanism is moved from the second position to the first position.

  According to the present invention, it is possible to provide an image forming apparatus capable of reducing the number of useless pressing operations in the fixing device.

FIG. 1 is a schematic view of an image forming apparatus according to an embodiment. It is an expansion schematic diagram of an operation part. It is a block of a control part. It is explanatory drawing of a jam process. FIG. 2 is a schematic external perspective view of a fixing device. FIG. 2 is a schematic perspective view of an essential part of one longitudinal end side (drive side) of the fixing device. It is a perspective view schematic diagram of the principal part of the longitudinal direction other end side (non-driving side) similarly. FIG. 2 is an enlarged cross-sectional schematic view of a main part of the fixing device. FIG. 2 is an exploded perspective view of the fixing belt unit. FIG. 3 is a schematic view of the fixing device in a pressurized state. FIG. 6 is a schematic view of the fixing device in a pressure released state. It is a flowchart of image formation mode. It is a flowchart of standby mode. It is a flowchart of the low power return mode. It is a flowchart of low power mode.

  Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.

"Example"
[Image forming apparatus]
FIG. 1 is a schematic view of an image forming apparatus A according to this embodiment. The image forming apparatus A is a tandem digital color copying machine (hereinafter simply referred to as a copying machine A) using a transfer type electrophotographic system. FIG. 1 shows a schematic configuration of a cross section of the recording material (sheet) P along the conveyance direction. A recording material (hereinafter, referred to as a sheet or a sheet of paper) P is one on which a toner image is formed. Specific examples of the paper P include plain paper, resin-like sheet substitutes for plain paper, thick paper, overhead projectors, and the like.

  Hereinafter, the main configuration of the copying machine A will be described based on FIGS. 1 to 4. The copying machine A includes an engine unit (apparatus main body) 600 that forms a toner image on a sheet P, and an image reading unit (reading unit) 601 disposed thereabove and reading an image of a document. Further, on the front surface of the copying machine A, an operation unit 700 for operating the copying machine is disposed approximately halfway between the engine unit 600 and the image reading unit 601. Further, on the rear side of the engine unit 600, a control unit 800 (FIG. 3) for controlling the operation of the engine unit 600 and the image reading unit 601 is provided. FIG. 1 is a view of the copying machine A as viewed from the front side, and the internal configuration of the engine unit 600 is depicted.

  FIG. 2 is an enlarged schematic view of the operation unit 700. As shown in FIG. The operation unit (reception unit) 700 is provided with operation buttons 701 operated to operate the copying machine A, and a touch panel (display unit) 702 capable of displaying information and operating.

  The operation button 701 includes a copy start button (original reading start button) 710, a ten key 711, a low power mode button 712, and the like. Here, the copy start button 710 causes the image reading unit 601 to read an image of a document and causes the image forming unit 10 to start a copying operation (copy operation) for causing the image forming unit 10 to form an image read by the image reading unit 601. It is a button for

  The touch panel 702 displays buttons that can be operated on the screen (a setting screen for copying an original). For example, a copy button 720 for setting a copy, a scan button 721 for transferring a read image, and a FAX button 722 for performing operation such as FAX transmission are displayed. Each button can be pressed by the operator, and a function corresponding to the pressed button is activated. That is, each button is a button for operating each function when pressed by the operator. That is, the copying machine A has a copying function for reading an original and forming an image of the read original on a sheet, and an operation unit 700 to which an instruction for reading an original can be input.

  Further, a human sensor 730 is provided in the operation unit 700. That is, the human sensor 730 is mounted on the main body of the copying machine A. The human sensor 730 uses an infrared sensor that detects a change in ambient temperature, and outputs a detection signal when the heat receiving object crosses the infrared. In this embodiment, as the human sensor 730 senses a human as a heat-sensitive body approaching the copying machine A, that is, based on human detection by the human sensor 730, as will be described later, Control content changes. In the present embodiment, the infrared temperature change detection method is used, but the configuration of the human sensor 730 is not limited to this, and any method of sensors that can detect a person may be used.

  As shown in FIG. 3, the control unit 800 mainly includes an engine controller 802 that controls units related to image formation of the engine unit 600, and a main controller 801 that controls the entire copying machine and the image reading unit 601. Prepare.

  The engine controller 802 is provided with a CPU (ENG) 810 as control means for controlling an image forming operation. Further, the engine controller 802 is provided with a ROM (ENG) 811 in which a program to be executed by the CPU (ENG) 810 is stored in advance, and a RAM (ENG) 812 in which variables of the program to be executed by the CPU (ENG) 810 are stored. It is done.

  The ROM (ENG) 811 stores the size and type of the sheet P, which is a condition for forming an image, an image forming color mode, and an image forming mode for one side or both sides. In addition, a control condition table for selectively guiding image forming conditions based on detection results from a temperature / humidity detecting member (not shown), a roller temperature detecting member (not shown), etc., and rotation of a motor according to an image forming mode Control conditions such as numbers are stored. The RAM (ENG) 812 stores, among the control conditions stored in the ROM (ENG) 811, conditions that need to be changed by the user (operator) and maintenance, variables and calculation values used for various controls, and Rewritable setting values are stored according to.

  The main controller 801 is provided with a CPU (CNT) 820 as control means for controlling the entire copying machine, controlling image reading, and controlling the operation unit 700. That is, the CPU (CNT) 820 functions as a display control unit that controls the display of the touch panel 702 in the operation unit 700. Further, the main controller 801 is provided with a ROM (CNT) 821 in which a program executed by the CPU (CNT) 820 is stored in advance and a RAM (CNT) 822 in which variables of the program executed by the CPU (CNT) 820 are stored. It is done.

  The ROM (CNT) 821 stores copy operation control and setting conditions, image reading control and setting conditions, FAX transmission / reception control and setting conditions, etc. under conditions for controlling the operation unit 700 and the image reading unit 601. It is done.

  The RAM (CNT) 822 stores, among control conditions stored in the ROM (CNT) 821, conditions that need to be changed by the user or maintenance, variables and calculation values used for various controls, and rewriting according to the situation Possible settings are stored. In addition, ROM (ENG) 811 and RAM (CNT) 812 store the conditions of image forming mode M 1, standby mode M 2, low power recovery mode M 3, and low power mode M 4 which are main operation modes of engine unit 600. doing.

  The image forming mode M1 is a mode in which the engine unit 600 can form an image and the image reading unit 601 can read an image. The standby mode M2 (third mode) is a mode in which the engine unit 600 is in the image forming preparation state and the image reading unit 601 is in the image readable state. The low power recovery mode M3 (second mode) is a mode in which the fixing device 40 is in the resting state, the image forming preparation state is other than the fixing device relationship of the engine unit 600, and the image reading unit 601 is in the image readable state. is there. The low power mode M4 (first mode) is a mode in which the engine unit 600 and the image reading unit 601 are in a resting state due to power reduction. As described later, the copier A can selectively execute these modes.

  In the low power mode M4, the CPU (CNT) 820 of the main controller 801 is operable, and the CPU (ENG) 810 of the engine controller 802 is in the inactive state (power supply is off) and the operating power is reduced constantly. It is a mode to be in the night driving state.

  An image reading unit 601, as a unit for reading a document, includes a document table 610 for reading a single document, and an automatic document feeder for reading a large number of documents (an apparatus for automatically conveying a document to a document reading unit: hereinafter referred to as ADF) It consists of 611.

  A document table 610 is an image reading unit that reads one image, and is used to read an image of a single document, a book, or the like. The operation unit 700 mainly includes a platen reading unit (not shown) and a pressure plate unit (not shown), and an original is placed on the platen reading unit (not shown) and the pressing unit (not shown) holds the document. The user presses the copy start button 710 or the scan button 721 of the touch panel 702. Thus, the image reading is performed by the document platen reading unit (not shown). The pressure plate portion (not shown) is openable / closable (openable / closable), and a pressure plate sensor 620 for detecting the open / close state is provided.

  The ADF 611 is used to read an image while automatically feeding a document, and can continuously read a plurality of documents. Mainly composed of an ADF reader (not shown) and a document feeder (not shown), the document is placed on the document feeder (not shown) and the copy start button 710 of the operation unit 700 and the scan button 721 of the touch panel 702 Press down. By this, while the document is automatically fed, the image reading is performed by the ADF reading unit (not shown). Further, the document feed unit (not shown) is provided with a document detection sensor 621 for detecting the presence or absence of a document.

  In the document reading operation, an image is read from the document table 610 or the ADF 611, the image data is converted into an electric signal, and transmitted to the laser scanner 6 of the engine unit 600.

  The engine unit 600 includes an image forming unit 10 for forming a toner image. The image forming unit 10 includes an imaging unit UY that forms a Y (yellow) toner image, an imaging unit UM that forms an M (magenta) toner image, and an imaging unit UC that forms a C (cyan) toner image. , Bk (black) color toner image forming image forming unit UBk. Further, the laser scanner unit 6 and the intermediate transfer belt unit 7 are provided. Each image forming unit U is an electrophotographic process mechanism, and includes a photosensitive drum 1, a charger 2, a developer 3, a primary transfer charger 4, and a drum cleaner 5.

  Since the electrophotographic process and the image forming operation of the image forming unit 10 having this configuration are known, the description thereof will be omitted. The toner images of the respective colors are superimposed in a predetermined manner and primarily transferred onto the rotating belt 8 of the intermediate transfer belt unit 7 from the drum 1 of each image forming unit U. As a result, a color toner image of Y + M + C + Bk superimposed on four colors is formed on the belt 8.

  On the other hand, the sheet feeding roller 11 of the cassette sheet feeding unit is driven at a predetermined control timing, so that the sheets P stacked and accommodated in the sheet feeding cassette 9 are fed out one by one, and the post-sheet feeding conveyance path The sheet is fed to a pair of registration rollers 13 through 12. The pair of registration rollers 13 temporarily receives the sheet P, and if the sheet P is skewed, it straightens. Then, the registration roller pair 13 synchronizes with the toner image on the belt 8 and sends the sheet P to the secondary transfer portion 15 which is a pressure contact nip portion between the belt 8 and the secondary transfer roller 14. The color toner images on the belt 8 are collectively secondarily transferred to the sheet P (on the sheet) by the secondary transfer roller 14 at once.

  The sheet P having passed through the secondary transfer unit 15 is introduced into the fixing device 40 through the pre-fixing conveyance path 16. The sheet P is conveyed to a fixing device (fixing unit) 40 and is heated and pressed to fix the toner image on the sheet P.

  In the single-sided image forming mode in which a toner image is formed (printed) on only one side of the sheet P, the sheet P conveyed upward from the upward exit of the fixing device 40 is switched to the side of the sheet discharge roller 18 by the switching flapper 17 The sheet is guided and discharged to the sheet discharge tray 19 as a single-sided image formed product.

  In the case of the double-sided image forming mode in which toner images are formed on both sides of the sheet P, the sheet P on which the single-sided image has been formed from the fixing device 40 is conveyed by the discharge roller 18 to the tray 19 and the rear end portion is fixed. And the sheet discharge roller 18 is reversely rotated. Thus, the sheet is switchback conveyed and introduced into the duplex conveying path 21.

  Then, the sheet P passes through the double-sided conveyance path 21 and is reintroduced into the conveyance path 12 after feeding in the front side of the pair of registration rollers 13 by the conveyance roller 22 in the front / back reverse state. Thereafter, the sheet P passes through the same process as in the case of the single-sided image forming mode, and is discharged to the sheet discharge tray 19 as a double-sided image formed on which the toner image is formed on the other side.

  The portion formed by the switchback operation of the flapper 17 and the discharge roller 18 is an example of the reversing means. In the present embodiment, the sheet discharge roller 18 reverses the sheet, but in order to enhance the productivity of printing (image formation), the sheet discharge may be performed by providing a reversing portion, providing a plurality of sheet discharge portions, or the like. The reversing may be performed at a place other than the roller 18.

  A manual feed unit (manual feed tray) 23 is provided in the outer portion of the engine unit 600 as a paper feed unit other than the paper feed cassette 9. The manual sheet feeding portion 23 can easily set the sheet P, for example, when the user wants to form an image on a sheet P of a type other than the sheet P set in the sheet feeding cassette 9, and for the purpose of considering user operability. It is provided.

  In image formation by paper feeding (paper feeding) from the manual paper feeding unit 23, the paper P set in the manual paper feeding unit 23 is driven by driving the paper feeding roller 24 at a predetermined control timing. It is sent out one by one. The sheet P passes through the conveyance path 25 and is introduced by the conveyance roller 22 into the post-feed conveyance path 12 on the front side of the registration roller pair 13. Thereafter, the image formation is executed as in the case of the sheet feeding from the sheet feeding cassette 9. The manual feed unit 23 is provided with a manual feed sensor (detection unit) 230 for detecting the presence or absence of the sheet P, and can detect the presence or absence of the sheet P in the manual feed unit 23. There is.

  The manual feed sensor 230 may be configured to be able to detect whether or not the sheet P is present on the manual feed unit 23. Therefore, the manual feed sensor 230 may be configured to detect the presence of the sheet P on the manual feed unit 23 (that is, “presence”), or the sheet P on the manual feed unit 23 may be It may be configured to detect absence (ie, "absent").

  In the former case, for example, when the sheet P is present on the manual sheet feeding unit 23, the manual sheet feeding sensor 230 responds by outputting a detection signal, and the sheet P is placed on the manual sheet feeding unit 23 If there is no detection signal, the sensor does not react and does not output a detection signal.

  In the latter case, for example, when the sheet P is not present on the manual sheet feeding unit 23, the manual sheet feeding sensor 230 responds by outputting a detection signal, and the sheet P is placed on the manual sheet feeding unit 23 If there is no detection signal when it is present, the sensor does not react and does not output a detection signal.

  In the present embodiment, as an example, the manual feed sensor 230 will be described as detecting that the sheet P on the manual feed unit 23 is present (that is, “presence”), as in the former case.

  As a means for detecting the state of the sheet P being conveyed on the conveyance path, a sheet detection sensor is provided on the conveyance path. In the copying machine A of FIG. 1, the registration sensor 200 performs sheet detection downstream of the registration roller pair 13. Further, the inner sheet discharge sensor 201 performs sheet detection downstream of the fixing device 40. Further, the paper discharge sensor 202 performs sheet detection downstream of the paper discharge roller 18. The CPU 810 of the engine controller 802 selectively shifts to the next process in accordance with the detection signals of the sensors 200, 201, 202.

  For example, if the on time of any of the sensors is longer than the prescribed time on the sequence while the paper P is being transported on the transport path, or if the arrival at any of the sensors is behind the prescribed time on the sequence, , It is determined that the paper is jammed somewhere (jamming occurred). Then, the CPU 810 stops the drive unit (not shown) of each roller based on the detection signal so that the paper jam does not progress.

  In the engine unit (apparatus main body) 600, the door 26 has a hinge 27 as a rotation center for the purpose of removing the sheet P jammed from the inside of the apparatus after the sheet P is jammed inside the apparatus and each sensor detects a jam. As shown in FIG. 4, it is provided to be able to turn to the right (open and turn). The door 26 is equipped with the pre-fixing conveyance path 16, the secondary transfer roller 14, and one roller (right side in the figure) of the pair of registration rollers 13. Therefore, when the door 26 is opened, the conveyance path other than the fixing device 40 is opened from the conveyance path 12 after sheet feeding to the discharge roller 18. As a result, it is possible to easily remove the sheet jammed in the transport path.

  When the manual feed portion 23 is not used, the outer surface of the door 26 can be folded and stored as shown by a two-dot chain line in FIG. At the time of use, as shown by the solid line in FIG. 1, it can be developed in a predetermined inclination angle posture outward from the outer surface of the door 26.

[Fixing device]
FIG. 5 is a schematic perspective view of the fixing device 40. As shown in FIG. FIG. 6 is a schematic perspective view of the main part of the fixing device 40 at one longitudinal end side (drive side), and FIG. 7 is a schematic perspective view of the main part at the other longitudinal end side (non-driving side). FIG. 8 is a schematic cross-sectional view of the main parts of the fixing device 40. As shown in FIG.

The fixing device 40 is a belt heating type image heating device, and is roughly classified into a fixing belt unit 110 including a fixing belt (first rotating body : endless belt ) 100, an elastic pressure roller (second rotating body : A driving rotating body ) 101, and a fixing frame (apparatus case) 115 accommodating these components. Hereinafter, the fixing belt unit 110 is referred to as a unit 110. A nip portion (fixing nip portion) N is formed by the cooperation of the fixing belt 100 as a pair of rotating members and the pressure roller 101 (FIG. 8). The nip portion N is a portion that nips and conveys the sheet P carrying the unfixed toner image T and fixes the toner image by heat and pressure.

  As shown in FIG. 8, the unit 110 includes a cylindrical fixing belt 100, a heater holder (pressure member) 103, a heater (heating member) 102, a pressure stay (belt frame) 104, and a flange member (belt guide) 105A. It is an assembly by 105B etc. FIG. 9 is a schematic exploded perspective view of the unit 110, and the pressure roller 101 is also drawn.

(1) Fixing Belt The fixing belt 100 (hereinafter referred to as the belt 100) is a thin, hollow endless belt-like heat transfer member having flexibility and heat resistance. The belt 100 is made of a heat-resistant resin such as a polyimide film or a PEEK film having a total thickness of 150 μm or less in order to reduce heat capacity and improve quick startability. An elastic layer of a rubber material with high thermal conductivity is formed on a resin layer provided with a conductive material so that the thermal conductivity is high, and a fluorocarbon resin release layer is formed on the surface to form an endless shape with an inner diameter of φ25 mm. It is formed.

  In this example, a 30 μm thick polyimide was used as the base layer, a 70 μm thick elastic layer and a silicone rubber having a thermal conductivity of 1.0 W / m · K, and a 30 μm thick PFA tube as the releasing layer. The PFA layer is preferably a sheet or coat layer having high releasability, and for example, a fluororesin layer can be used. Alternatively, a highly heat-resistant sheet-like member represented by polyester, polyethylene terephthalate, polyimideamide or the like may be used as a base layer, an electrically conductive layer, and a surface release layer may be further laminated thereon.

(2) Heater Holder The heater holder 103 is a nip forming member in which the heater 102 is fixed and supported. The heater holder 103 is a heat insulating member such as a heat resistant resin which is long along the longitudinal direction (width direction) of the belt 100 in a substantially semi-circular wedge shape in cross section. From the viewpoint of energy saving, it is desirable to use a material having little heat conduction to the pressure stay 104, and for example, a heat resistant resin such as heat resistant glass, polycarbonate, liquid crystal polymer or the like is used.

(3) Heater The heater 102 is a low heat capacity horizontally long plate-like heating element which rapidly raises its temperature by energization, and is a ceramic heater in this embodiment. The heater 102 forms a heating element by thick-film printing and firing an Ag / Pd paste on an AlN substrate having a thin and thin plate-like shape and good thermal conductivity. Then, a glass coating layer having a thickness of about 50 to 60 μm is integrally provided as a sliding insulating member on the heating element to constitute a ceramic heater. In the present embodiment, the heating resistance layer is formed on an AlN substrate having a thickness of 600 μm. The heater 102 is fitted and held in a groove formed on the outer surface of the heater holder 102 along the length of the holder.

  On the other hand, a chip-like thermistor TH1 is provided on the substrate opposite to the side where the heat generating body is provided with the AlN substrate interposed therebetween. The thermistor TH1 is adhesively fixed on the electrode pattern previously formed by thick film printing on the opposite side of the region where the heat generating body is present, and monitors the temperature of the AlN substrate. Furthermore, the thermistor TH2 is provided at a position near the end of the heat generating body. The thermistors TH1 and TH2 are fixed to the substrate at a predetermined pressure by pressing means such as a spring (not shown) in order to detect a temperature which exceeds the heat resistant temperature of the adhesive.

(4) Pressure Stay The pressure stay 104 is a rigid member that is long along the width direction of the belt 100 and receives a reaction force from the pressure roller 101, and is a material that is not easily bent even if high pressure is applied. In this embodiment, a SUS304 shaped material having a U-shaped cross section is used. The pressure stay 104 is disposed inside the heater holder 104 to support the heater holder 103.

(5) Flange member The belt 100 is loosely fitted (externally inserted) to the assembly of the heater holder 103, the heater 102, and the pressure stay 104 described above. Both end portions 104 a of the pressure stay 104 project outward from the openings at both end portions of the belt 100. The flange members 105A and 105B are fitted to both end portions 104a of the pressure stay 104, respectively. The belt 100 is located between the opposing flange portions 105a and 105a of the fitted flange members 105A and 105B. The flange members 105A and 105B are restricting members that restrict the longitudinal movement and circumferential shape of the belt 100 in the unit 110.

  The flange members 105A and 105B are molded products of heat-resistant resin such as PPS, liquid crystal polymer, phenol resin, etc., and have flange portions (seat portions) 105a, shelf portions 105b, and pressed portions 105c. .

  The flange portion 105 a is a portion that receives an end edge surface of the belt 100 and restricts the movement of the belt 100 in the thrust direction, and has an outer shape larger than the outer shape of the belt 100. The shelf portion 105b is provided in an arc shape on the inner surface side of the flange portion 105a, and holds the inner surface of the belt end portion to maintain the cylindrical shape of the belt 100. The pressed portion 105c is provided on the outer surface side of the flange portion 105a, and receives a pressing force by pressing mechanisms 118A and 118B described later.

(6) Pressure roller The pressure roller 101 uses a cylindrical core metal 101a made of metal such as iron or aluminum as a core material, and an elastic layer 101b of a flexible rubber material such as sponge or silicone rubber on the outer peripheral side of the core metal. The surface layer is provided with a PFA layer as a release layer 101c.

  In this embodiment, the surface of the core metal 101a of iron, aluminum or the like is subjected to surface roughening treatment such as blasting, and then cleaning is performed, and then the core metal 101a is inserted into a cylindrical shape, and liquid silicone rubber is contained in the mold. And the elastic layer 101b is formed by heating and curing. At this time, in order to form a resin tube layer such as a PFA tube or the like as the release layer 101c on the surface of the elastic layer 101b, a tube having a primer applied to the inner surface in advance is inserted into the mold. Thereby, the tube 101c and the rubber layer 101b are bonded simultaneously with heat curing of the rubber as the elastic layer 101b. The pressure roller 101 thus molded is subjected to secondary vulcanization after being demolded.

  In this embodiment, the diameter of the core metal 101a of the pressure roller 101 is φ15 mm, the thickness of the elastic layer 101b is 5 mm, silicone rubber of Asker hardness 64 °, the thickness of the PFA tube of the release layer 101c is 50 μm, and the outer diameter is about The pressure roller 101 has a diameter of 25 mm.

  The pressure roller 101 is rotatably supported by bearings 114 at one end and the other end of the cored bar 101a between the side plates 116A and 116B at one end and the other end of the fixing frame 115, respectively.

  The unit 110 is arranged parallel to the pressure roller 101 with the side of the heater 102 facing the pressure roller 101 between the side plates 116A and 116B. The flange members 105A and 105B in the unit 110 are slidably fitted in the direction of the pressure roller 101 in guide holes 117 in which the respective pressed portions 105c are formed symmetrically in the side plates 116A and 116B.

  Then, the flange members 105A and 105B receive a predetermined pressing force in the direction toward the pressing roller 102 by pressing mechanisms 118A and 118B described later on the pressed portions 105c, respectively. In this example, the pressure was 125 N on each side and 250 N in total pressure.

  By the pressing force, all of the flange members 105A and 105B of the unit 110, the pressing stay 104 and the heater holder 103 are pressed in the direction of the pressing roller 101. Therefore, the heater holder 103 and the heater 102 are pressed against the pressure roller 101 via the belt 100 against the elasticity of the elastic layer 101 b with a predetermined pressure, so that the sheet is interposed between the belt 100 and the pressure roller 101. A nip portion N having a predetermined width in the transport direction X is formed.

(7) Fixing Operation A drive gear G1 is disposed concentrically and integrally on one end side of the cored bar 101a of the pressure roller 101. The driving force of the fixing motor (drive source) 92 controlled by the CPU 810 is transmitted to the gear G1 via the drive transmission mechanism of the fixing drive unit 90. Thus, the pressure roller 101 is rotationally driven at a predetermined speed in the counterclockwise direction of the arrow R101 in FIG. As the pressure roller 101 is rotationally driven, a rotational torque is exerted on the belt 100 at the nip portion N by the frictional force with the pressure roller 101.

  Thereby, the belt 100 is driven to rotate the outer circumference of the heater holder 103 and the pressure stay 104 in the clockwise direction indicated by the arrow R100 while the inner surface of the belt 100 slides in close contact with the heater 102 and a part of the heater holder 103 in the nip N. . The circumferential speed of the belt 100 substantially corresponds to the circumferential speed of the pressure roller 101. A lubricant (not shown) is applied to the sliding surfaces of the belt 100, the heater 102 and the heater holder 103 in order to reduce the frictional force. The lubricant is oil applied in this embodiment. As oil, silicone oil etc. which can be used under high temperature environment are preferred.

  Further, the CPU 810 starts energization of the heater 102 from a power supply unit (not shown). Although a feed path from the feed unit to the heater 102 is omitted in the figure, it is made via a wire and a connector electrically connecting the feed unit and the heater 102. The heater 102 rapidly rises in temperature by this energization. The thermistor TH1 outputs a signal corresponding to the temperature of the heater 102 to the CPU 810. The CPU 810 controls the power supplied from the power supply unit to the heater 102 so that the heater temperature is raised to a predetermined target set temperature and the temperature is adjusted based on the heater temperature detected by the thermistor TH1.

  In the fixing device state described above, the sheet P on which the unfixed toner image T is formed is introduced from the image forming unit 10 to the fixing device 40, and nipped and conveyed by the nip portion N. The heat of the heater 102 is applied via the belt 100 in the process of nipping and transporting the sheet P at the nip portion N. The unfixed toner image T is melted by the heat of the heater 102 and fixed to the sheet P by the pressure applied to the nip portion N.

(8) Pressing Mechanism On the outside of the side plates 116A and 116B at one end and the other end of the fixing frame 115, pressing mechanisms 118A and 118B at the one end and the other end are disposed, respectively. Since both the pressure applying mechanisms 118A and 118B have the same symmetrical structure, the pressure applying mechanism 118A on one end side will be described as a representative.

  The pressing mechanism 118 A has a pressing lever 112 and a pressing spring 113. The pressing lever 112 is attached to the side plate 116A so that the pressing lever 112 can pivot around the shaft 111. The pressing lever 112 extends from the shaft portion 111 to the opposite side to the shaft portion 111 side via the position of the pressed portion 105 c of the flange member 105A. The pressure spring 113 is an elastic member that rotationally urges the pressure lever 112 about the shaft portion 111 in a direction in which the pressure lever 112 abuts against the pressed portion 105c of the flange member 105A.

  In the present embodiment, a through hole (not shown) is provided in the pressure lever portion on the opposite side to the shaft portion 111 with the pressed portion 105c in between, and a long pressure adjusting screw 132 is provided in the through hole. The screw tip is inserted and screwed into the screw hole 133 on the side plate 116A side. Then, a coiled pressure spring 113 is externally fitted on a screw portion between a head (seating surface) 132 a of the screw 132 and the pressure lever 112 so as to be contracted. Therefore, in the free state, the pressure lever 112 abuts against the pressed portion 105c of the flange member 105A by the compression reaction force of the pressure spring 113 to apply pressure.

  By tightening the screw 132, the head 132a of the screw 132 can shorten the spring length of the pressure spring 113, and the spring load applied to the pressure lever 112 can be increased. Since the pressure lever 112 is rotatably supported by the side plate 116A, a rotational moment is generated around the shaft 111 by the compression reaction force of the pressure spring 113, and the flange member 105A is directed to the pressure roller 201. Is pressed with a predetermined pressure.

  The pressing mechanism 118A at one end has been described above, but the pressing mechanism 118B at the other end is the same as the pressing mechanism 118A at one end.

(9) Pressure Release Mechanism The pressure release mechanism 119 cancels the pressure applied by the pressure mechanisms 118A and 118B at one end and the other end. In the present embodiment, the pressure release mechanism 119 has cams 120 at one end and the other end for swinging the pressure levers 112 of the pressure mechanisms 118A and 118B at the one end and the other end.
The two cams 120 have the same shape with a predetermined amount of eccentricity, and one end of the cam shaft 123 rotatably supported by the bearings 131 and 131 between the side plates 116A and 116B and the other It is fixed to the end in the same phase, and rotates integrally with the cam shaft 123. The cams 120 at one end and the other end correspond to the tip end of the pressing lever 112 of the pressing mechanisms 118A and 118B at the one end and the other end, respectively.

  At one end side of the cam shaft 123, a drive gear G2 is coaxially integrally fixed. The driving force of the fixing motor 92 controlled by the CPU 810 is transmitted to the gear G 2 through the drive transmission mechanism of the cam drive unit 91.

  FIG. 10 shows a state in which the belt 100 and the pressure roller 101 are in pressure contact and a nip portion N having a predetermined width is formed therebetween. In this state, the cams 120 on the one end side and the other end side of the pressure release mechanism 119 have minimum protruding portions with respect to the pressure levers 112 of the pressure mechanisms 118A and 118B on the one end side and the other end, respectively. The opposing pressure lever 112 is in a non-contact rotation angle posture.

  Therefore, the pressing lever 112 is in a free state, and the flange members 105A and 105B at one end and the other end are respectively operated by the pressing spring 113 and the pressing lever 112 of the pressing mechanism 118A and 118B at the one end and the other end. It is pressurized. As a result, the belt 100 and the pressure roller 101 are in pressure contact with each other, and the nip portion N having a predetermined width is formed between the two (in the first position).

  FIG. 11 shows the pressure released state. In the pressurized state shown in FIG. 10, the driving force of the fixing motor 92 is transmitted to the gear G2 via the drive transmission mechanism of the cam drive unit 91 to rotate the cam shaft 123, and the cam 120 at one end and the other end. Are each rotated in the same phase. Then, the rotation angle attitude is such that the maximum protuberances face the pressing levers 112 on one end side and the other end side.

  Then, the pressure levers 112 at the one end and the other end move away from the pressed portions 105c of the flange members 105A and 105B at the one end and the other end by the cam 120 respectively. It is pushed up against. As a result, the pressing of the fixing belt 100 and the pressing roller 101 is released (second position).

(10) Press Release Control and Press Control The press release operation is performed to enhance the removal operability of the jammed sheet when the sheet P is jammed while the sheet P is being conveyed at the nip portion N. Further, the pressure of the belt 100 and the pressure roller 101 is released so that the pressure mark of the belt 100 and the pressure roller 101 is not attached in the pressure contact state for a predetermined time or more without driving the apparatus.

  Among the rotational operations of the cam 120, there is a sensor flag 121 coaxially with the cam shaft 123 which is a support shaft of the cam 120 as means for detecting the pressure contact position and the pressure release position. The rotational direction position is detected by the contact / separation sensor 122. The contact / separation sensor 122 transmits an infrared ray in the sensor, and the sensor flag 121 transmits a signal by blocking or transmitting the infrared ray.

  In the operation from the pressure contact state of FIG. 10 to the pressure release state of FIG. 11, the CPU (ENG) 810 causes the fixing motor 92 of the fixing drive unit 90 to stop in response to a pressure release instruction signal from the engine controller 802. After the stop, the fixing motor 92 is rotationally driven in the motor reverse direction V (FIG. 5) which is the CCW direction, and the cam 120 starts rotating in the W direction by drive transmission of the drive path of the cam drive unit 91. Along with that, the sensor flag 121 coaxially located on the cam shaft 123 is simultaneously rotated.

  The contact / separation sensor 122 is in the transmission state before the rotation operation of the sensor flag 121, and while the transmission state is maintained, the sensor flag 121 blocks the infrared radiation area of the contact / separation sensor 122 and the contact / separation sensor 122 shields the light. In this state, the cam 120 is at the pressure release completion position. The pressure release state is detected by the transition of the output signal of the contact / separation sensor 122 at this time, and the fixing motor 92 is stopped to complete the pressure release.

  A pressure release command signal from the engine controller 802 is output when each sheet detection sensor detects a jam, when the door 80 is opened, when the copying machine shifts to the low power mode M4, or the like. .

  Further, the pressure contact operation from the pressure released state of FIG. 11 to the pressure applied state of FIG. 10 is for the belt 100 and the pressure roller to return the fixing device 40 to the image forming state by the pressure contact command signal from the engine controller 802. The pressure welding operation of 101 is started.

  First, the CPU (ENG) 810 rotationally drives the fixing motor 92 in the motor reverse direction V which is the CCW direction, and the cam 120 starts rotating in the W direction by drive transmission of the drive path of the cam drive unit 92. Along with this, the sensor flag 121 coaxially located on the cam shaft 123 is simultaneously rotated.

  When releasing the pressure, the contact and separation sensor 122 is in the light shielding state, and while the light shielding state is maintained while the sensor flag 121 is rotating, the sensor flag 121 rotates in the infrared irradiation area of the contact and separation sensor 122 when rotating to the pressure release completion position. Then, the contact / separation sensor 122 is in the transmission state. The nip portion N is detected as a pressure contact state by the transition of the output signal of the contact / separation sensor 122 at this time, and the fixing motor 92 is stopped to complete the pressure contact.

  The press-contact command signal from the engine controller 802 is output when the copying machine enters an image forming mode while shifting to the image forming mode M1. The state in which the image formation is performed is a state such as when the copy button 720 is pressed or an image formation signal is input from an external device such as a PC (personal computer).

  By moving the pressing mechanism to the position where the fixing motor 92, the cam drive unit 91, the cam 120, etc. are in the pressure contact state and the release state as described above, the fixing device 40 is in the pressure contact state. , And can be taken off. That is, the fixing motor 92, the cam driving unit 91, the cam 120 and the like function as a moving mechanism for moving the pressing mechanism.

(11) Mode Transition Next, the mechanism involved in the operation of the copying machine to transition to the image forming mode M1, the standby mode M2 and the low power mode M4 will be described based on FIG. 2 and FIG. 12 to FIG. FIG. 12 is a flowchart of the image forming mode. FIG. 13 is a flowchart of the standby mode. FIG. 14 is a flowchart of the low power recovery mode. FIG. 15 is a flowchart of the low power mode.

  When the copying machine A finishes image formation from the state of the image forming mode M1 in the image forming operation state and passes the transition time to the standby mode M2 stored in the RAM (ENG) 812, the copying machine shifts to the standby mode M2 (FIG. 12: S1 to S4). In the present embodiment, the setting value of the standby mode M2 transition time is set to 15 seconds (S4).

  The state of the standby mode M2 is the first stage of the standby state of the copying machine, and each image forming unit is in an image forming preparation state in which image forming can be performed as soon as an image forming signal is input to the engine controller 802. (FIG. 13: S5 to S13). At this time, in the fixing device 40, the belt 100 and the pressure roller 101 are in a pressure contact state, and the heater 102 and the fixing motor 92 are in a non-operating state (non-energized state).

  When the transition time from the standby mode M2 to the low power mode M4 stored in the RAM (ENG) 812 passes, the copying machine A shifts to the low power mode M4 (S7, S14, S15). In the present embodiment, the setting value of the transition time to the low power mode M4 is one minute (S7).

  Further, in response to pressing the low power mode button 712 from the standby mode M2 state, the copying machine A shifts to the low power mode M4 (S8, S14, S15).

  The low power mode M4 is the second stage of the standby state of the copying machine, and the standby power of the copying machine is reduced as much as possible to save energy. Therefore, the engine controller 802 including the engine unit 600 and the CPU (ENG) 810 and the image reading unit 601 are paused to be in the image formation impossible state (S15).

  Since the engine unit 600 and the operation unit 700 have a return function from the low power mode M4, the functional units other than the function are suspended. The CPU (CNT) 820 of the main controller 801 is in the operating state in the nightly operating state in which the CPU (CNT) 820 is operable for the return operation from the low power mode M4. At this time, in the fixing device 40, the belt 100 and the pressure roller 101 are in the pressure released state, and the heater 102 and the fixing motor 92 are in the non-operating state (non-energized state).

  Next, the mechanism involved in the operation of the copying machine A returning from the low power mode M4 will be described. In the low power mode M4 state (during the execution of the first mode), the functional units other than the return condition from the low power mode M4 are in the inactive state. Here, in order to recover from the low power mode M4, the recovery operation is performed from the recovery condition function unit, and when the recovery condition signal is output, the copying machine A shifts from the low power mode M4 to the low power recovery mode M3 ( Figure 15: S27 to S28).

In the present embodiment, the return condition from the low power mode M4 is as follows: [Condition 1]: The sheet of the manual feed sensor 203 by setting the sheet (sheet) P to the manual feed unit (manual tray) 23 Detection (Fig. 15: S27)
That is, condition 1 is that the manual feed sensor 203 detects that the sheet P has been set in the manual feed unit 23. For example, when the operator sets the sheet P to the manual feed portion 23 in a state where the sheet P is not placed, the manual feed sensor 203 detects the manual feed based on the detection result of the sensor. It can be detected that the sheet P on the section 23 has changed from the non-present state to the present state.

  The state in which the copying machine A shifts from the low power mode M4 to the low power recovery mode M3 (during execution of the second mode) is different from the state in which the state of the image forming mode M1 shifts to the standby mode M2. In the standby mode M2, each image forming unit is ready for image formation so that an image can be formed as soon as an image forming signal is input to the engine controller 802, but the low power recovery mode M3 is fixed. The device 40 remains inactive. At this time, in the fixing device 40, the belt 100 and the pressure roller 101 are in the pressure released state, and the heater 102 and the fixing motor 92 are in the non-operating state (non-energized state).

  The reason why the fixing device 40 is in the inactive state in the mode M3 after power recovery is as follows. As described above, in the standby mode M2, the image forming unit stands by in a state where image formation can be started. Therefore, assuming that the low power mode M4 shifts to the standby mode M2, the image forming unit performs an initial operation for returning to a state where image formation can be started. At this time, since the belt 100 and the pressure roller 101 are in the pressure release state in the low power mode M4, if the transition to the standby mode M2 is temporarily made, the fixing device 40 changes from the pressure release state to the pressure contact state. Become.

  However, there is also a possibility that the state recovery from the low power mode M4 is recovery of the copying machine A for purposes other than image formation. In the present embodiment, the purpose other than the image formation is, for example, document scanning, FAX transmission, or the like by digitizing the document. Also, for example, a user often sets paper that is frequently used in the manual feed tray on the manual feed tray and does not immediately form an image. For these purposes, since the image formation on the sheet P is not performed, the fixing device 40 is also not used.

  Therefore, when returning from the low power mode M4 for the purpose other than image formation, it is useless to change the fixing device 40 from the pressure release state to the pressure contact state.

  As described above, even when the low-power mode M4 may be restored for purposes other than image formation, when the fixing device 40 is changed from the pressure release state to the pressure contact state each time, members of the change mechanism (for example, It may lead to the deterioration of the cam 120).

  Therefore, in the copying machine A, when returning to the low power recovery mode M3 from the low power recovery mode M4 in the pressure release state, in the low power recovery mode M3, as described below, the belt 100 and the pressure roller 101 are Leave in the pressure released state. Thereafter, when shifting to the image forming mode M1 or the standby mode M2, under the control of the CPU (ENG) 810, the belt 100 and the pressure roller 101 are changed from the pressure release state to the pressure contact state.

  Further, the fixing device 40 is in a state in which the image formation can be started (that is, the fixing process can be started) only under the condition that the signal as the image forming condition is input. As soon as an image formation signal is input to the engine controller 802, the image formation ready state in which image formation is possible is made.

  In the present embodiment, the conditions for shifting to the next mode are as follows. The mode transitioned by the following operation is transitioned to either the image forming mode M1 or the standby mode M2.

[Condition 2]: After pressing the copy button 720 of the touch panel 702, press the copy start button 710 of the operation unit 700. [Condition 3]: Press the copy button 720 of the touch panel 702, then press each setting button of the screen. Under the [condition 2] and [condition 3], the copy button 702 is displayed on the touch panel 702.

When the user presses the copy start button 710 under the image forming conditions of [condition 2], the image forming mode M1 is entered. The fixing device 40 rotationally drives the fixing motor 92 in the motor reverse direction V, which is the CCW direction, and performs a pressure contact operation between the fixing belt 100 and the pressure roller 101. Then, in order to perform an image forming operation after pressure contact, power supply to the heating member 102 and the fixing motor 92 are rotationally driven in the motor reverse direction Y which is the CW direction. (FIG. 14: S17, S20, S21, S23)
After the copy button 720 is pressed under the image forming condition of [condition 3], when each setting button on the screen is pressed and input is performed, the mode is shifted to the standby mode M2. That is, when the copy button 702 is pressed, a screen displaying each setting button is displayed on the touch panel 702. When one of the setting buttons displayed on the screen after the copy button 720 is pressed is pressed (that is, a predetermined instruction is input), the mode shifts to the standby mode M2. The fixing device 40 causes the fixing motor 92 to rotate in the motor reverse direction V, which is the CCW direction, and performs a pressure contact operation between the belt 100 and the pressure roller 101. (FIG. 14: S17, S20, S22, S24)
Then, in order to perform the standby initial operation in the image formation preparation state after pressure contact, the energization of the heater 102 and the fixing motor 92 are rotationally driven in the motor reverse direction Y which is the CW direction, and the belt 100 and the pressure roller 101 are rotated. Put in a preheated condition. When an image formation instruction is received during the transition to the preheating state, the image forming operation is performed by switching from the standby mode M2 to the image formation mode M1 (S25).

  The characteristic configuration of the image forming apparatus of the above embodiment is summarized as follows. An image forming unit 10 for forming a toner image T on a recording material P, and a pair of rotating members 100 for heating by sandwiching and conveying the recording material P on which the toner image T is formed by the image forming unit 10 by a nip N A fixing unit 40 provided with a fixing unit 101 is provided.

  In addition, pressing mechanisms 118A and 118B for pressing the pair of rotating bodies 100 and 101, a pressure releasing mechanism 119 for releasing the pressing of the pair of rotating bodies 100 and 101 by the pressing mechanisms 118A and 118B, and a pressure releasing mechanism And driving units 91 and 92 for driving the driving unit 119. The control unit 800 also controls the operations of the drive units 91 and 92 and controls the image forming unit 10 at the time of image formation.

  In addition, a manual feed tray 23 of a recording material to be fed to the image forming unit 10 is provided. In the non-image forming state, the low power mode is provided to put the control unit 800 in the inactive state by reducing the power. When transitioning to the low power mode, in conjunction with the transition, the control unit 800 is put into the resting state while the pair of rotating bodies 100 and 101 are put in the pressure releasing state. Then, when returning from the low power mode, the control unit 800 returns to the operable state while maintaining the pressure release state of the pair of rotating bodies 100 and 101.

  Here, when shifting to the low power mode, it is not limited to a control mode in which the pair of rotating bodies 100 and 101 are released from pressure in conjunction with the transition. It is possible to adopt a control mode in which the pressure is released in 2 hours.

  The return from the low power mode is performed based on the recording material set in the manual feed tray 23.

  The copying machine A has an operation unit 700 provided with a touch panel 702 for displaying an original copy setting screen and an original reading start button 710. The copying machine A releases the pressure on the pair of rotating bodies 100 and 101 in response to pressing of the document reading start button 710 in a state where the setting screen is displayed on the touch panel 702 after returning from the low power mode. Switch from state to pressure.

  The copying machine A has an operation unit 700 provided with a touch panel 702 for displaying an original copy setting screen and an original reading start button 710. In response to the setting screen being operated while the setting screen is displayed on the touch panel 702 after returning from the low power mode, the copying machine A adds the pair of rotating bodies 100 and 101 from the pressure release state. Switch to pressure state.

  That is, the pressing operation of the fixing unit is not performed even if the trigger for returning from the low power mode is performed. Then, by displaying the copy screen on the operation unit and not performing the pressing operation except when the setting button or the start key is pressed, the unnecessary pressing operation is avoided.

  As described above, in the transition from the pressure release state after returning to the low power mode to the pressure contact state in the pressure contact portion of the fixing portion, the pressure release state is maintained except for the image forming condition. Then, the pressure mechanism is operated only when pressure welding is required. Thus, the number of useless pressing operations of the fixing device can be reduced.

  Further, as described above, in the standby mode M2 in which the fixing device 40 is in the pressure contact state, when the transition time to the low power mode M4 is passed, the low power mode M4 is entered and the fixing device 40 is in the pressure release state. If an unnecessary pressure contact operation is performed when the low power mode is restored, the fixing device 40 may shift to the pressure release state again after the transition time without inputting the image forming signal. Therefore, as described above, by reducing the number of useless pressing operations when returning from the low power mode M4, it is possible to reduce the number of useless pressure release operations.

  As a result, it is possible to provide an image forming apparatus having a fixing device capable of suppressing the deterioration of the pressing mechanism and the operation mechanism thereof and prolonging the life.

  In this embodiment, as the fixing device 40, an endless rotating member not stretched on the heater side and a roller on the pressure side are used, but the fixing method is not limited to this fixing method. For example, an endless rotating body may be used on the pressure roller side, or a tension type endless rotating body fixing system may be used on the heater side.

  Further, in the embodiment, as shown in FIG. 11, although the pressure release of the belt 100 and the pressure roller 101 is released, the present invention is not limited to this. A low pressure contact or the like may be used as long as the applied pressure is not applied.

  That is, in the above-described embodiment, the pressure release state is described by taking as an example the case where the belt 100 and the pressure roller 101 are separated or in contact with each other at zero pressure. It may be a configuration. That is, the contact pressure at the nip portion is smaller (that is, the pressing force is smaller than the pressure contact state) than the pressure contact state where the nip portion N for fixing the belt 100 and the pressure roller 101 is formed. It may be in a pressure released state.

  In the above description, an apparatus for heating and fixing an unfixed toner image formed on a sheet as a fixing apparatus has been described as an example, but the present invention is not limited thereto. For example, it may be a device (also referred to as a fixing device in this case) that increases the gloss (glossiness) of the image by heating and re-fixing the toner image temporarily attached to the sheet.

  The heating means for heating the rotating body is not limited to the ceramic heater of the embodiment. An apparatus configuration using a heater such as an electromagnetic induction heating means, a halogen heater, an infrared lamp, a nichrome wire heater, or the like of an internal heating type or an external heating type can also be employed.

  The image forming apparatus is not limited to the electrophotographic full color image apparatus of the embodiment, and may be an image forming apparatus for forming a monochrome image. Further, the present invention is not limited to the electrophotographic method, and may be an image forming apparatus that forms a toner image using another method such as an electrostatic recording method or a magnetic recording method.

  A · · Image forming apparatus, 10 · · · Image forming unit, 40 · · · Fixing unit (fixing device), 100 · 101 · · · A pair of rotating members (fixing belt and pressure roller), N · · Nip portion, P · · · · Recording material (paper), T · · · Toner image, 118A · 118B · · Pressure mechanism, 119 · · Pressure release mechanism, 91 · 92 · · · Drive unit for pressure release mechanism, 800 · · Control unit

Claims (10)

An image forming apparatus for forming an image;
With a manual feed tray,
A detection unit that detects whether a sheet is placed on the manual feed tray;
An image forming unit for forming an image on a sheet supplied from the manual feed tray;
An endless belt for heating an image formed on the sheet at the nip portion by pre-Symbol image forming unit,
A heater for heating the endless belt;
A driving rotating body which cooperates with the endless belt to form the nip portion and which rotationally drives the endless belt ;
A pressure mechanism for pressing the endless belt toward the drive rotating body;
A first position at which the nip portion is formed by the endless belt and the drive rotating body;
The pressing mechanism can take a second position in which a force applied between the endless belt and the drive rotating body is smaller by the pressing mechanism than when the pressing mechanism is positioned at the first position. A moving mechanism for moving the pressure mechanism, and
A control unit that controls the operation of the movement mechanism;
A reception unit that receives an input of an instruction regarding an image forming operation for forming an image on a sheet by the image forming unit;
The image forming apparatus selectively selects one of a plurality of modes including a first mode in which the control unit is in a resting state, and a second mode in which power is supplied to the control unit. Is viable and
When the first mode is being executed and the pressing mechanism is in the second position, the detection unit detects that the sheet has been placed on the manual feed tray. The image forming apparatus shifts the mode to be executed to the second mode, and the receiving unit receives an input of a predetermined instruction regarding the image forming operation while the second mode is being executed, The image forming apparatus, wherein the control unit controls the moving mechanism such that the pressing mechanism moves from the second position to the first position. The reception unit includes a display unit, and a display control unit that controls display of the display unit.
The display control unit is configured to display the setting screen on the display unit in response to an instruction from the operator to display the setting screen of the image forming operation , and the predetermined instruction is operator while displaying the setting screen is to manually on the display unit, the image forming apparatus according to claim 1, characterized in that. It has a reading unit that reads the image of a document,
2. The image forming apparatus according to claim 1, wherein the predetermined instruction is an instruction to start reading by the reading unit for a copying operation in which the image forming unit forms an image read by the reading unit on a sheet. Image forming apparatus. The image forming apparatus is capable of executing a third mode in which power is supplied to the control unit and the pressing mechanism is at the first position.
In conjunction with the transition of the mode executed by the image forming apparatus from the second mode to the third mode, the control unit causes the pressure mechanism to be at the first position. The image forming apparatus according to any one of claims 1 to 3, wherein the movement mechanism is controlled. The image forming apparatus is capable of executing a third mode in which power is supplied to the control unit and the pressing mechanism is at the first position.
The receiving unit can receive an input of an instruction to shift from the second mode to the third mode,
The control unit causes the pressure mechanism to move to the first position in response to the reception unit receiving an input of an instruction to shift from the second mode to the third mode. The image forming apparatus according to any one of claims 1 to 3, wherein the mechanism is controlled. An image forming apparatus for forming an image;
With a manual feed tray,
A detection unit that detects whether a sheet is placed on the manual feed tray;
An image forming unit for forming an image on a sheet supplied from the manual feed tray;
An endless belt which heats an image formed on a sheet by the image forming unit at a nip portion;
A heater for heating the endless belt;
A driving rotating body which cooperates with the endless belt to form the nip portion and which rotationally drives the endless belt;
A pressure mechanism for pressing the endless belt toward the drive rotating body;
The pressing mechanism can take a first position where the nip portion is formed by the endless belt and the drive rotating body , and a second position where the endless belt and the drive rotating body are separated. A moving mechanism for moving the pressure mechanism;
A control unit that controls the operation of the movement mechanism;
A reception unit that receives an input of an instruction regarding an image forming operation for forming an image on a sheet by the image forming unit;
The image forming apparatus selectively selects one of a plurality of modes including a first mode in which the control unit is in a resting state, and a second mode in which power is supplied to the control unit. Is viable and
When the first mode is being executed and the pressing mechanism is in the second position, the detection unit detects that the sheet has been placed on the manual feed tray. The image forming apparatus shifts the mode to be executed to the second mode, and the receiving unit receives an input of a predetermined instruction regarding the image forming operation while the second mode is being executed, The image forming apparatus, wherein the control unit controls the moving mechanism such that the pressing mechanism moves from the second position to the first position. The reception unit includes a display unit, and a display control unit that controls display of the display unit.
The display control unit is configured to display the setting screen on the display unit in response to an instruction from the operator to display the setting screen of the image forming operation , and the predetermined instruction is operator while displaying the setting screen is to manually on the display unit, the image forming apparatus according to claim 6, characterized in that. It has a reading unit that reads the image of a document,
7. The image forming apparatus according to claim 6, wherein the predetermined instruction is an instruction to start reading by the reading unit for a copying operation in which the image forming unit forms an image read by the reading unit on a sheet. Image forming apparatus. The image forming apparatus is capable of executing a third mode in which power is supplied to the control unit and the pressing mechanism is at the first position.
In conjunction with the transition of the mode executed by the image forming apparatus from the second mode to the third mode, the control unit causes the pressure mechanism to be at the first position. The image forming apparatus according to any one of claims 6 to 8, which controls a moving mechanism. The image forming apparatus is capable of executing a third mode in which power is supplied to the control unit and the pressing mechanism is at the first position.
The receiving unit can receive an input of an instruction to shift from the second mode to the third mode,
The control unit causes the pressure mechanism to move to the first position in response to the reception unit receiving an input of an instruction to shift from the second mode to the third mode. The image forming apparatus according to any one of claims 6 to 8, which controls a mechanism.