JP6064819B2 - Image forming apparatus and control program - Google Patents

Description

  The present invention relates to an image forming apparatus and a control program.

  2. Description of the Related Art Conventionally, an image forming apparatus including a fixing device that heats a fixing belt using electromagnetic induction is known. For example, in Patent Document 1, when the warming-up operation is started, the pressure roll is separated from the fixing belt, and when a predetermined temperature lower than the fixable temperature is reached, the pressure roll is brought into pressure contact with the fixing belt. An image forming apparatus is disclosed in which a toner image forming operation is started when a fixing belt pressed against a pressure roll reaches a fixable temperature.

JP 2011-118298 A

  An object of the present invention is to reduce the time required to reach a fixable state.

An image forming apparatus according to claim 1 is provided.
A toner image forming device for forming a toner image on a recording material;
A fixing member that is heated by electromagnetic induction and contacts a recording material on which an unfixed toner image is formed, and fixes the toner image to the recording material by heat;
A magnetic field generator for generating an alternating magnetic field for electromagnetically heating the fixing member;
A pressure member that is movable between a pressure position that pressurizes the fixing member and a spaced position that is separated from the fixing member, and through which the recording material passes between the fixing member when the pressure member is located;
A mover for moving the pressure member between the pressure position and the separation position;
Prior to toner image formation by the toner image forming device, the magnetic field generator generates the AC magnetic field when the pressure member is in the separated position, and the fixing member can fix the toner image. When the heating member is heated to a predetermined temperature lower than the fixing temperature, the pressing member is temporarily moved to the pressing position, and then the pressing member is returned to the separation position so that the fixing member reaches the fixing temperature. When heated, the pressure member is moved to the pressure position to start the toner image formation by the toner image forming device, and prior to the toner image forming by the toner image forming device, The magnetic field generator generates the AC magnetic field when the pressure member is in the separated position, and the fixing member is heated to a predetermined temperature lower than a fixing temperature at which the toner image can be fixed. And the pressure member at the pressure position The moved, and a control unit used depending the fixing member is heated to a fixing temperature and a second heating to initiate the formation of a toner image by the toner image forming device to the operating conditions,
It is provided with.

An image forming apparatus according to claim 2
The control unit selectively uses the first heating and the second heating according to the thickness of the recording material, and applies the second heating to the recording material thicker than the recording material on which the first heating is performed. It is what is executed.

An image forming apparatus according to claim 3
The control unit selectively uses the first heating and the second heating according to a power supply voltage, and causes the second heating to be executed under a power supply voltage lower than the power supply voltage at which the first heating is executed. It is characterized by being.

An image forming apparatus according to claim 4
The control unit uses the first heating and the second heating properly according to the environmental temperature, and causes the second heating to be executed under an environmental temperature lower than the environmental temperature at which the first heating is executed. It is characterized by being.

An image forming apparatus according to claim 5
The control unit selectively uses the first heating and the second heating according to the member temperature of the fixing member before heating, and the first heating is performed under a member temperature higher than the member temperature at which the first heating is performed. 2 heating is performed.

An image forming apparatus according to claim 6
The control unit selectively uses the first heating and the second heating depending on the gloss after the toner image is fixed, and causes the second heating to be executed for a gloss higher than the gloss for which the first heating is performed. It is characterized by being.

A control program according to claim 7 is:
On the computer,
A toner image forming device that forms a toner image on a recording material, and a fixing member that is heated by electromagnetic induction and contacts the recording material on which an unfixed toner image is formed, and fixes the toner image to the recording material with heat And a magnetic field generator that generates an alternating magnetic field for electromagnetically heating the fixing member, a pressurizing position that pressurizes the fixing member, and a spaced position that is spaced apart from the fixing member. A pressure member through which the recording material passes between the fixing member when in the pressure position, and a mover that moves the pressure member between the pressure position and the separation position. Control the image forming device
Prior to toner image formation by the toner image forming device, the magnetic field generator generates the AC magnetic field when the pressure member is in the separated position, and the fixing member can fix the toner image. When the heating member is heated to a predetermined temperature lower than the fixing temperature, the pressing member is temporarily moved to the pressing position, and then the pressing member is returned to the separated position. First heating for moving the pressure member to the pressure position and starting the toner image formation by the toner image forming device when heated to the fixing temperature;
Prior to toner image formation by the toner image forming device, the magnetic field generator generates the AC magnetic field when the pressure member is in the separated position, and the fixing member can fix the toner image. When the fixing member is heated to a predetermined temperature lower than the fixing temperature, the pressing member is moved to the pressing position, and when the fixing member is heated to the fixing temperature, the toner image forming device Second heating to initiate formation;
According to the operation status of the image forming apparatus.

  According to the image forming apparatus according to the first aspect and the control program according to the seventh aspect, it is possible to reduce the time required to reach the fixable state as compared with the case where the present configuration is not provided.

  According to the image forming apparatus of the second aspect, the time required to reach the fixable state can be reduced according to the thickness of the recording material.

  According to the image forming apparatus of the third aspect, the time required to reach the fixable state can be reduced according to the power supply voltage.

  According to the image forming apparatus of the fourth aspect, the time required to reach the fixable state can be reduced according to the environmental temperature.

  According to the image forming apparatus of the fifth aspect, the time required to reach the fixable state can be reduced according to the member temperature of the fixing member before heating.

  According to the image forming apparatus of the sixth aspect, the time required to reach the fixable state can be reduced according to the gloss after the toner image is fixed.

1 is a schematic configuration diagram of a copying machine as an embodiment of an image forming apparatus of the present invention. It is sectional drawing which showed the structure of the fixing device. FIG. 6 is a diagram illustrating a state in which a fixing belt generates heat by an alternating magnetic field. FIG. 3 is a front view showing a driving mechanism of a fixing device. It is a figure which shows the state by which the pressurization roll was contacted with the heating belt by the retract mechanism. It is a figure which shows the state from which the pressure roll was separated from the heating belt by the retract mechanism. It is the block diagram which showed schematically the internal structure of the control part. It is a flowchart showing the main process in warm-up operation. It is a flowchart showing the warming-up operation | movement using heat storage start-up. It is a graph showing the temperature change in a fixing device in the heat storage start-up. It is a flowchart showing the warming-up operation | movement using the preheating starting. It is a graph showing the temperature change in a fixing device in preheating start-up.

  Embodiments of the present invention will be described below.

FIG. 1 is a schematic configuration diagram of a copying machine as an embodiment of an image forming apparatus of the present invention.
A copying machine 1 shown in FIG. 1 is a so-called tandem color copying machine, and also has a function as a printer that receives image data from a computer and outputs an image.

  The copying machine 1 includes an image forming process unit 10 that forms an image corresponding to image data of each color, a control unit 20 that controls the operation of the entire copying machine 1, and an image reading unit that reads an image of a document and generates image data. 30. For example, the image data is obtained from the communication unit 21, the image reading unit 30 or the communication unit 21 that is connected to an external device such as a personal computer (PC) 3 and receives image data, and image processing is performed on the image data. An image processing unit 25 to be applied, a user interface (UI) unit 22 for receiving operation input from the user and displaying various information to the user, an environment sensor 26 for detecting the temperature and humidity environment of the copying machine 1, and supplying power to each unit A main power supply 28 is provided.

  The image reading unit 30 includes a first platen glass 31 on which the document is placed in a stationary state and a second platen glass 32 that forms an optical opening for reading the document being conveyed.

  The document on the first platen glass 31 is covered with a platen cover 33 that can be opened and closed with respect to the first platen glass 31 and is in close contact with the first platen glass 31. The platen cover 33 is provided with an open / close detection sensor (not shown) that detects the open / closed state of the platen cover 33, and information related to the open / closed state of the platen cover 33 is transmitted to the control unit 20.

  Furthermore, the image reading unit 30 includes a feeder 34 that accommodates a plurality of documents and conveys each document so that one or both sides of the document pass through the second platen glass 32. The feeder 34 is provided with a document detection sensor (not shown) that detects that a document is stored, and information regarding the presence or absence of the document is transmitted to the control unit 20.

  The image forming process unit 10 includes four image forming engines 50Y, 50M, 50C, and 50K. These four image forming engines 50Y, 50M, 50C, and 50K are engines that form toner images with toners of yellow (Y), magenta (M), cyan (C), and black (K), respectively. In the following description, in a scene where it is not necessary to distinguish each color, the symbols Y, M, C, and K representing the colors are omitted, and the description is made using only numerals.

  Each image forming engine 50 includes a photosensitive drum 51 that rotates in the direction of arrow A. An electrostatic latent image is formed on the surface of the photosensitive drum 51 by electrostatic potential distribution. Further, around each photosensitive drum 51, a charger 52, an exposure device 53, a developing device 54, a primary transfer device 55, and a cleaner 56 are provided. Here, the primary transfer unit 55 is disposed inside the intermediate transfer belt 60 with the intermediate transfer belt 60 interposed between the primary transfer unit 55 and the photoreceptor 50. Further, the developer 54 stores a developer containing toner of a color corresponding to each image forming engine 50.

  The intermediate transfer belt 60 is an endless belt that is wound around a plurality of rolls 61 and circulates in the direction of arrow B. A secondary transfer device 70 and a cleaner 71 are disposed around the intermediate transfer belt 60.

  Three sheet trays T1, T2, and T3 are provided in the lower part of the image forming process unit 10. In each of the paper trays T1, T2, T3, the sheets before printing are stacked and stored. These paper trays T1, T2, T3 can be pulled out from the casing of the copying machine 1 for replenishing paper. Each of the paper trays T1, T2, and T3 can store papers of different paper quality (for example, thin paper, plain paper, coated paper, glossy paper, etc.) and papers of different sizes. The image forming process section 10 is provided with a pick-up roll 41 and a separating roll 42 corresponding to each of the paper trays T1, T2, and T3. 44 is also provided.

A fixing device 80, a transport roll 45, and a discharge roll 46 are provided in the upper part in the image forming process unit 10, and a paper stacking tray 47 is provided in the discharge unit that has come out of the image forming process unit 10 from the discharge roll 46. Is provided.
<Description of image forming process>
In the copying machine 1 of the present embodiment, when the UI unit 22 receives a copying instruction from a user regarding a document placed on the first platen glass 31 of the image reading unit 30 or a document stored in the feeder 34, the copying machine 1. The control unit 20 recognizes the copy instruction. When the communication unit 21 receives a print job (a series of image data), the control unit 20 of the copier 1 recognizes the reception. As a result of such recognition by the control unit 20, the copier 1 can perform image data generated by the image reading unit 30 and a print job received by the communication unit 21 under operation control by the control unit 20. Then, the following image forming process is executed.

  First, the image processing unit 25 performs predetermined image processing on the image data from the PC 3 and the image reading unit 30. As a result, the image data for each color is decomposed and sent to the image forming engines 50Y, 50M, 50C, and 50K of the image forming process unit 10. For example, in the image forming engine 50K that forms a black (K) toner image, the surface is uniformly charged by the charger 52 while the photosensitive drum 51 rotates in the direction of arrow A, and is transmitted from the image processing unit 25. The exposure device 53 emits exposure light modulated in accordance with the K-color image data to scan and expose the photosensitive drum 51. As a result, an electrostatic latent image relating to the K color image is formed on the photosensitive drum 51. The K-color electrostatic latent image formed on the photosensitive drum 51 is developed with the K-color toner in the developer by the developing unit 54, and a K-color toner image is formed on the photosensitive drum 51. Similarly, yellow (Y), magenta (M), and cyan (C) toner images are also formed in image forming engines 50Y, 50M, and 50C other than black (K).

  Each color toner image formed on the photoconductive drum 51 of each image forming engine 50 is sequentially electrostatically transferred (primary transfer) onto the intermediate transfer belt 60 moving in the direction of arrow B by the primary transfer unit 55, and each color toner is transferred. A superimposed toner image is formed. The toner remaining on the photosensitive drum 51 after the primary transfer is removed from the photosensitive drum 51 by the cleaner 56. Further, the superimposed toner image on the intermediate transfer belt 60 is conveyed to the location where the secondary transfer unit 70 is disposed as the intermediate transfer belt 60 moves.

  On the other hand, the pick-up roll 41 takes out one sheet from the sheet tray containing the sheet designated by the operation of the UI unit 22 among the three sheet trays T1, T2, and T33. When a plurality of sheets are taken out and overlapped, the separating roll 42 is surely separated into one sheet. Then, the sheet is conveyed in the direction of the arrow D1 by the conveyance roll 43 on the conveyance path indicated by a broken line in FIG. The sheet conveyed to the standby roll 44 is adjusted in timing so that the superimposed toner image on the intermediate transfer belt 60 reaches the position of the secondary transfer unit 70 so that the sheet reaches the secondary transfer unit 70 as well. It is sent out in the direction D2. The superimposed toner image is collectively electrostatically transferred (secondary transfer) onto the conveyed paper by the transfer electric field formed by the secondary transfer unit 70. The toner remaining on the intermediate transfer belt 60 after the secondary transfer is removed from the intermediate transfer belt 60 by the cleaner 71.

  A combination of elements from the image forming engine 50 to the secondary transfer device 70 corresponds to an example of a toner image forming device that forms a toner image on a recording material.

  The sheet on which the toner image is transferred by the secondary transfer unit 70 is conveyed in the direction of the arrow D3 while holding the unfixed toner image, and reaches the fixing unit 80. The toner image on the paper conveyed to the fixing device 80 receives heat and pressure by the fixing device 80 and is fixed on the paper. The sheet on which the fixed image is formed is conveyed in the direction of arrow D4, further conveyed in the direction of arrow D5 by the conveyance roll 45, and stacked on the sheet stacking tray 47 by the discharge roll 46.

In this manner, the image forming process in the copying machine 1 is repeatedly executed for the number of printed sheets.
<Description of fuser structure>
Next, the structure of the fixing device 80 will be described.

  FIG. 2 is a sectional view showing the structure of the fixing device.

  The fixing device 80 includes an induction heater 81, a heating belt 82, a pressure roll 83, and an excitation circuit 84. The induction heater 81 generates an alternating magnetic field and heats the heating belt 82 by electromagnetic induction. The excitation circuit 84 supplies the induction heater 81 with electric power for generating an alternating magnetic field. The heating belt 82 rotates in the direction of the arrow C1, holds the unfixed toner image, and contacts the sheet conveyed in the direction of the arrow D3 to heat the toner on the sheet.

  The induction heater 81 corresponds to an example of the magnetic field generator according to the present invention, the heating belt 82 corresponds to an example of the fixing member according to the present invention, and the pressure roll 83 corresponds to the pressure member according to the present invention. It corresponds to an example.

  Inside the heating belt 82, a magnetic heating member 821 is provided on the induction heater 81 side, and a pressing member 822 is provided on the pressure roll 83 side. Further, a support structure 823 that supports them is shown between the heat generating member 821 and the pressing member 822. Further, a temperature sensor 824 for measuring the temperature of the heating belt 82 in contact with the inner surface of the heating belt 82 is also shown here.

  The heat generating member 821 is a member that increases the heating efficiency of the heating belt 82 by the induction heater 81. The pressing member 822 is disposed on the inner surface of the heating belt 82 at a position facing the pressure roll 83 with the heating belt 82 interposed therebetween, and the pressing surface 822a faces the inner surface of the heating belt 82 and is heated by the pressing surface 822a. A member that contacts the inner surface of the belt 82 and presses the heating belt 82 toward the pressure roll 83. The pressing member 822 forms a nip portion with the heating belt 82 sandwiched between the pressure roll 83 and the pressing member 822. The sheet passes while being sandwiched between the pressure roll 83 and the heating belt 82 at the nip portion. Heat from the heating belt 82 and pressure from the pressure roll 83 are applied to the sheet to fix the unfixed toner image.

  The support structure 823 is constructed of a material having high rigidity, and maintains the uniformity in the longitudinal direction in the pressure at the nip portion (nip pressure).

  The pressure roll 83 is pressed against the outer surface of the heating belt 82 and rotates in the direction of arrow C2, for example, at a process speed of 140 mm / s, and sandwiches the sheet conveyed in the direction of arrow D3 between the heating belt 82. For example, it is a roll that pressurizes with a load of 20 kgf. The surface of the pressure roll 83 is an elastic body that is deformed so as to follow the shape of the pressing surface 822a of the pressing member 822 when pressed.

  In the induction heater 81, an exciting coil 811 for induction heating is provided with a gap of, for example, 0.5 to 2 mm from the outer peripheral surface of the heating belt 82. The excitation coil 811 is a litz wire bundled with conductive wires wound in a closed loop shape. When an alternating current is supplied from the excitation circuit 84 to the excitation coil 811, the excitation coil 811 has a closed loop shape around it. An alternating magnetic field centered around the litz wire wound around is generated.

  The induction heater 81 is also provided with a magnetic core 812 that forms a magnetic path of an alternating magnetic field on the opposite side of the heating belt 82 with the excitation coil 811 interposed therebetween. The magnetic core 812 is formed of a material with high magnetic permeability such as ferrite resin. The magnetic core 812 has a magnetic force line such that a magnetic line of force generated by the alternating magnetic field generated by the exciting coil 811 crosses the heating belt 82 from the exciting coil 811 toward the heat generating member 821, passes through the heat generating member 821, and returns to the exciting coil 811. The passage (magnetic path) is formed. By forming a magnetic path with the magnetic core 812, an alternating magnetic field (line of magnetic force) generated by the excitation coil 811 is concentrated in a region facing the magnetic core 812 of the heating belt 82.

  FIG. 3 is a diagram illustrating a state in which the fixing belt generates heat due to an alternating magnetic field.

  As shown in FIG. 3, the heating belt 82 includes a base layer 825 made of a synthetic resin having high heat resistance, a conductive layer 826 stacked on the base layer 825, and an elastic layer 827 that improves the fixability of the toner image. A multilayer belt having a surface release layer 828 made of a material that is coated on the uppermost layer and has high releasability. The conductive layer 826 is a layer of a heating element that is electromagnetically heated by an alternating magnetic field generated by the induction heater 81. For example, a metal such as iron, cobalt, nickel, copper, or chromium is used.

When an alternating magnetic field (lines of magnetic force) emitted from the magnetic core 812 crosses the conductive layer 826 of the heating belt 82, an eddy current is generated in the conductive layer 826 so as to generate a magnetic field that prevents the change of the alternating magnetic field. Then, when the eddy current I flows through the conductive layer 826, Joule heat W (W = I ² R) proportional to the resistance value R of the conductive layer 826 is generated, and the heating belt 82 is heated.

Further, although it is weaker than the heating belt 82, the heating element 821 also generates heat due to an eddy current generated by an AC magnetic field. The heat of the heating element 821 stabilizes the temperature of the heating belt 82.
<Description of Fixing Unit Drive Mechanism>
FIG. 4 is a front view showing a driving mechanism of the fixing device.

  FIG. 4 shows the fixing device 80 as viewed from the paper entry side. The fixing device 80 includes a driving motor 85 as a driving source for the pressure roll 83 and the heating belt 82.

  The pressure roll 83 is rotationally driven from the drive motor 85 via a transmission gear 91 fixed to the shaft of the drive motor 85 and a transmission gear (not shown) fixed to the rotation shaft 96 of the pressure roll 83. Power is transmitted.

  On the other hand, when the pressure roller 83 is in contact with the heating belt 82, the pressure roller 83 is driven to rotate. Here, a drive system other than such driven rotation is also prepared.

  At both ends of the support structure 823 (see FIG. 3) provided inside the heating belt 82, end caps that rotationally drive the heating belt 82 in the circumferential direction while maintaining a circular cross-sectional shape of both ends of the heating belt 82. A member 86 is rotatably supported. Then, the heating belt 82 directly receives the rotational driving force from the both end portions via the end cap member 86 and rotates. The rotational driving force from the drive motor 85 is transmitted to the shaft 93 via the transmission gears 91 and 92, and is transmitted from the transmission gear 94 coupled to the shaft 93 to the gear portions 95 of the end cap members 86 at both ends. Thereby, the rotational driving force is transmitted from the end cap member 86 to the heating belt 82, and the end cap member 86 and the heating belt 82 are integrally rotated. Note that a torque limiter (not shown) is disposed between the transmission gear 92 and the shaft 93, and when the heating belt 82 is driven by the pressure roll 83, a rotational driving force is applied from the transmission gear 91 to the shaft 93. Is not transmitted.

Further, the fixing device 80 is provided with a retract mechanism that moves the pressure roll 83 toward and away from the heating belt 82. The retract mechanism includes a rotary shaft 98 rotatably supported by a support 97, a displacement motor 90 that displaces the rotary shaft 98 within a predetermined angle range, and pressure rollers 83 at both ends of the rotary shaft 98. There is provided a cam 99 which is fixed at a position facing the rotary shaft 96 and swings when the rotary shaft 98 is displaced. Further, a spring 88 that urges the pressure roll 83 in a direction away from the heating belt 82 (downward in the drawing) is also provided. This retract mechanism corresponds to an example of a mobile device according to the present invention.
<Description of retract operation>
FIGS. 5 and 6 are diagrams for explaining the operation when the retract mechanism brings the pressure roll 83 into and out of contact with the heating belt 82.

  FIG. 5 shows a state where the pressure roll is brought into contact with the fixing belt by the retract mechanism, and FIG. 6 shows a state where the pressure roll is separated from the heating belt.

  As shown in FIG. 5, when the displacement motor 90 (see FIG. 4) displaces the rotary shaft 98 so that the top F0 of the cam 99 faces the center of the heating belt 82, the top F0 of the cam 99 is pressurized. The rotating shaft 96 of the roll 83 is pushed into the heating belt 82 against the urging force of the spring 88 (see FIG. 4). Thereby, the pressure roll 83 is pressed against the outer surface of the heating belt 82.

  On the other hand, as shown in FIG. 6, when the displacement motor 90 (see FIG. 4) displaces the rotary shaft 98 so that the top F0 of the cam 99 is inclined by an angle θ with respect to the central direction of the heating belt 82, the additional force is increased. The rotary shaft 96 of the pressure roll 83 moves in the direction of arrow E in FIG. 6 from the heating belt 82 side along the side face F1 of the cam 99 by the biasing force of the spring 88 (see FIG. 4). Thereby, the pressure roll 83 is separated from the heating belt 82.

  The position of the pressure roll 83 shown in FIG. 5 corresponds to an example of the pressure position according to the present invention, and the position of the pressure roll 83 shown in FIG. 6 corresponds to an example of the separation position according to the present invention.

In the present embodiment, the movement of the pressure roll 83 by such a retract mechanism is appropriately executed during a so-called warm-up operation, thereby shortening the warm-up time for raising the heating belt 82 to a fixable temperature. Such a warm-up operation is controlled by the control unit 20 shown in FIG. The control unit 20 corresponds to an example of a control unit referred to in the present invention.
<Description of internal configuration of control unit>
FIG. 7 is a block diagram schematically showing the internal configuration of the control unit.

  The control unit 20 controls the warm-up operation and the like. The main CPU 110 executes digital arithmetic processing according to a predetermined control program, the RAM 112 used as a work memory for the main CPU 110, and the main CPU 110 are used for processing. ROM 113 for storing various setting values to be stored, nonvolatile memory (NVM) 114 such as a flash memory backed up by a battery that can be rewritten and can retain data even when power supply is interrupted, and control unit 20 And an interface (I / F) unit 115 that inputs and outputs signals to and from each component unit (for example, a temperature sensor 824).

  Then, the main CPU 110 reads a control program from an external storage device (not shown) into the main storage device (RAM 112) and executes it, thereby realizing control such as a warm-up operation. This control program corresponds to an embodiment of the control program of the present invention.

In addition, as another provision form regarding this control program, there is a form that is provided in a state stored in the ROM 113 in advance and loaded into the RAM 112. Further, when a rewritable ROM 113 such as an EEPROM is provided, after the main CPU 110 is set, only a program is installed in the ROM 113 and loaded into the RAM 112. Further, there is a mode in which a program is transmitted to the control unit 31 via a network such as the Internet, installed in the ROM 113 of the control unit 31, and loaded into the RAM 112. Furthermore, there is a form in which the RAM 112 is loaded from an external recording medium such as a DVD-ROM or a flash memory.
<Description of warm-up operation>
Next, specific contents of the warm-up operation will be described. In the following description, the elements described in FIG. 1 and the like may be referred to by reference numerals without particular reference to the figure numbers as necessary. In addition, by describing the contents of the warm-up operation below, it also serves as a specific description of the above-described control program.

  FIG. 8 is a flowchart showing main processing in the warm-up operation.

  The control unit 20 is preset with an operation performed by the user (hereinafter referred to as “user operation”) as a pre-stage of the execution of the toner image forming operation. The control unit 20 controls the image reading unit 30, the UI unit 22, and the communication. The “operation by the user” is monitored based on the signal from the unit 21 (step S02). This “operation by the user” includes, for example, an operation of opening the platen cover 33 of the image reading unit 30 and is recognized by the main CPU 110 of the control unit 20 by acquiring information from the open / close detection sensor of the platen cover 33. Is done. In addition, an operation for storing a document in the feeder 34 of the image reading unit 30 is included, and information is acquired from the document detection sensor and is recognized by the main CPU 110. Furthermore, a user input operation to a liquid crystal touch panel and a numeric keypad provided in the UI unit 22 is also included, and the operation input information is acquired from the UI unit 22 and is recognized by the main CPU 110. Furthermore, reception of a print job by the communication unit 21 is also included, and the main CPU 110 recognizes the print job from the communication unit 21.

  When the control unit 20 recognizes such an operation by the user (Y in step S02), the control unit 20 (main CPU 110) confirms various operating conditions as described below. On the other hand, when the operation by the user is not recognized (No in Step 02), the control unit 20 continues to monitor the operation by the user (Step 02).

In order to confirm the operation status, first, in step S04, the environmental temperature in the installation environment of the copying machine 1 is acquired from the environmental sensor 26 and confirmed. If the environmental temperature is 20 ° C. or higher, the process proceeds to step S 06, and the temperature of the heating belt 82 at the start of warm-up (startup) is acquired from the temperature sensor 824 and confirmed. If the temperature of the heating belt 82 is less than 100 ° C., the process proceeds to step S08, and the voltage value is acquired from the main power supply 28 and confirmed. If the voltage value is 98 V or more, the process proceeds to step S10, and the paper quality of the paper instructed by the user from the UI unit 22 is acquired and confirmed. If the sheet has a thickness of less than 100 g / m ² , the process proceeds to step S12, and the image forming mode instructed by the user is acquired from the UI unit 22, and it is confirmed whether it is the gloss mode. If not in the gloss mode, the process proceeds to step S14, and a warm-up operation using “preheating start-up” described later is executed. This “preheating start-up” corresponds to an example of the first heating referred to in the present invention.

On the other hand, whether the environmental temperature is less than 20 ° C., the temperature of the heating belt 82 at the start of start-up is 100 ° C. or higher, and the voltage value of the main power supply 28 is less than 98V in the operation status confirmation If it is determined that the sheet thickness is 100 g / m ² or more or the gloss mode is instructed, the process proceeds to step S16, and “heat storage start-up” described later is performed. The warm-up operation using “is performed. This “heat storage start-up” corresponds to an example of the second heating referred to in the present invention.

  When the warm-up operation by either “preheating start-up” or “heat storage start-up” is completed, the control unit 20 instructs the image forming process unit 10 to start the toner image forming operation (step S18). When the control unit 20 recognizes the completion of a series of image forming processes (step S20), the control unit 20 returns to step S02 again and monitors the operation by the user.

  FIG. 9 is a flowchart showing a warm-up operation using heat storage start-up.

  The control unit 20 instructs the fixing device 80 to turn on the displacement motor 90 and separates the pressure roll 83 from the heating belt 82 by the retract mechanism so that the pressure roll 83 is not pressed against the heating belt 82. Then, the driving motor 85 is turned on to rotate the heating belt 82 (step 102). Thereafter, the control unit 20 instructs execution of heating of the heating belt 82 by the induction heater 81 (step 104).

  At this stage, since the pressure roll 83 is separated from the heating belt 82, heat does not flow from the heating belt 82 to the pressure roll 83 outside the heating belt 82. As a result, the outflow of heat from the heating belt 82 having a small heat capacity is suppressed, and the warm-up time for raising the heating belt 82 to the fixable temperature is reduced.

  Then, when the heating belt 82 reaches a predetermined temperature lower than the fixable temperature by heating (Yes in Step 106), the control unit 20 presses the pressure roll 83 against the heating belt 82 by a retract mechanism (Step S106). 108). Then, when the heating belt 82 to which the pressure roll 83 is in pressure contact reaches the fixable temperature (Yes in step 110), the warm-up operation using the heat storage start is finished, and the process proceeds to step S18 in the flowchart of FIG.

  At the end of the warm-up operation, since the pressure roll 83 is in pressure contact with the heating belt 82, it is predetermined between the heating belt 82 and the pressure roll 83 by the elastic force of both the pressing member 822 and the pressure roll 83. A nip portion having a high nip pressure is formed. That is, a state where fixing is possible with respect to both heat and pressure is realized.

  FIG. 10 is a graph showing a temperature change in the fixing device at the start of heat storage.

  The horizontal axis in FIG. 10 represents time, and the vertical axis represents temperature. Further, the thick solid line in the graph represents the temperature change of the heating belt 82, the thin solid line represents the temperature change of the heat generating member 821, and the dotted line represents the temperature change of the pressure roll 83.

  At the start of heating due to the start of heat storage, the pressure roll 83 is separated from the heating belt 82 as described above, so that the temperature of the heating belt 82 quickly rises as indicated by the thick solid line. Further, as indicated by the thin solid line, the temperature of the heat generating member 821 also rises, but is slower than that of the heating belt 82.

  Thereafter, at the latch timing when the pressure roll 83 comes into pressure contact with the heating belt 82, the temperature of the pressure roll 83 rapidly increases as indicated by the dotted line. On the other hand, the temperature rise of the heating belt 82 indicated by the thick solid line is dull, and the temperature of the heat generating member 821 indicated by the thin solid line is raised. At the timing when the temperature of the heating belt 82 reaches the fixable temperature and the image forming operation is started and the sheet enters the nip portion, the temperature of the heating member 821 catches up with the temperature of the heating belt 82. As a result, the heating belt 82 is thermally supplemented by the heat generating member 821, and the temperature necessary for fixing is maintained even when the image forming speed is high.

  In addition, since the pressure roller 83 is sufficiently heated at the paper entry timing, a sudden temperature drop (so-called droop) of the heating belt 82 due to paper entry is also avoided.

  FIG. 11 is a flowchart showing a warm-up operation using preheating start-up.

  The control unit 20 instructs the fixing device 80 to turn on the displacement motor 90 and separates the pressure roll 83 from the heating belt 82 by the retract mechanism so that the pressure roll 83 is not pressed against the heating belt 82. Then, the heating belt 82 is rotated by instructing the drive motor 85 to be turned on (step 202). Thereafter, the control unit 20 instructs execution of heating of the heating belt 82 by the induction heater 81 (step 204).

  At this stage, the warm-up time is reduced because the pressure roll 83 is separated from the heating belt 82 as in the case of the heat storage start-up.

  Then, when the heating belt 82 reaches a predetermined temperature lower than the fixable temperature by heating (Yes in Step 206), the controller 20 presses the pressure roll 83 against the heating belt 82 by the retract mechanism (Step S20). 208). However, in the preheating start-up, the pressurization of the pressure roll 83 is temporary, and the pressure roll 83 is separated from the heating belt 82 again at a predetermined timing.

  In the case of preheating start-up, since the pressure roll 83 is separated from the heating belt 82 even at this stage, the warm-up time is further reduced.

  Thereafter, when the heating belt 82 from which the pressure roll 83 is separated reaches the fixing possible temperature (Yes in Step 210), the control unit 20 presses the pressure roll 83 against the heating belt 82 by the retract mechanism (Step 212). Then, the warm-up operation using the preheating start is completed, and the process proceeds to step S18 in the flowchart of FIG.

  Even at the end of the warm-up operation using the preheating start-up, since the pressure roller 83 is in pressure contact with the heating belt 82, a nip portion having a predetermined nip pressure is formed, and both heat and pressure can be fixed. Is realized.

  FIG. 12 is a graph showing a temperature change in the fixing device during the preheating start-up.

  Also in FIG. 12, the horizontal axis represents time, and the vertical axis represents temperature. Further, the thick solid line in the graph represents the temperature change of the heating belt 82, the thin solid line represents the temperature change of the heat generating member 821, and the dotted line represents the temperature change of the pressure roll 83.

  Even at the start of heating by the preheating start-up, the pressure roll 83 is separated from the heating belt 82 as described above, so that the temperature of the heating belt 82 quickly rises as indicated by the thick solid line. Further, as indicated by the thin solid line, the temperature of the heat generating member 821 also rises, but is slower than that of the heating belt 82.

  Thereafter, at the first latch-on timing when the pressure roll 83 comes into pressure contact with the heating belt 82, the temperature of the pressure roll 83 rapidly increases as indicated by the dotted line. On the other hand, the temperature rise of the heating belt 82 indicated by the thick solid line is dull, and the temperature of the heat generating member 821 indicated by the thin solid line is raised.

  In the preheating start-up, the pressure roll 83 is separated from the heating belt 82 at the latch-off timing before the temperature of the heat generating member 821 catches up with the temperature of the heating belt 82, and the temperature rise of the pressure roll 83 is almost as shown by the dotted line. Stop. On the other hand, the temperature rise of the heating belt 82 is accelerated as indicated by a thick solid line. Then, the heat of the heating belt 82 is transferred to the pressure roll 83 somewhat at the second latch-on timing when the temperature of the heating belt 82 reaches the fixable temperature and the pressure roll 83 comes into pressure contact with the heating belt 82. At the timing when the forming operation is started and the sheet enters the nip portion, the temperature of the heat generating member 821 almost catches up with the temperature of the heating belt 82. As a result, the heating belt 82 is thermally supplemented by the heat generating member 821, and the temperature necessary for fixing is maintained even when the image forming speed is high.

  Thus, in the preheating start-up, the temperature of the heating belt 82 rises quickly from the latch-off timing to the second latch-on timing, so that the warm-up time is further reduced compared to the heat storage start-up.

  However, since the time during which the pressure roll 83 is heated is shorter than the heat storage start-up, depending on the operation situation, a rapid temperature drop (so-called droop) of the heating belt 82 due to the entry of the paper may occur. Therefore, the operation state is confirmed in steps S04 to S12 of the flowchart shown in FIG. 8, and preheating start-up is used in an operation state where droop is avoided. As a result, the warm-up time is shortened according to the operating condition. Specifically, in the confirmation in step S04, the warm-up time is shortened according to the environmental temperature, and in the confirmation in step S06, the warm-up time is shortened according to the temperature of the heating belt 82 at the start of startup, and in step S08. In the confirmation in step S10, the warm-up time is shortened according to the voltage value of the main power supply 28. In the confirmation in step S10, the warm-up time is shortened according to the sheet thickness. In the confirmation in step S12, the warm-up time is reduced. It is shortened according to the mode.

  In the above description, a tandem type color copying machine is illustrated as an embodiment of the present invention, but the image forming apparatus of the present invention may be a revolver type color copying machine or a monochrome copying machine. The image forming apparatus of the present invention may be applied to a facsimile or a printer.

DESCRIPTION OF SYMBOLS 1 Copier 10 Image formation process part 20 Control part 22 User interface (UI) part 26 Environmental sensor 28 Main power supply 50Y, 50M, 50C, 50K Image formation engine 80 Fixing device 81 Induction heater 82 Heating belt 824 Temperature sensor 83 Pressurization roll

Claims (7)

A toner image forming device for forming a toner image on a recording material;
A fixing member that is heated by electromagnetic induction and contacts a recording material on which an unfixed toner image is formed, and fixes the toner image to the recording material by heat;
A magnetic field generator for generating an alternating magnetic field for electromagnetically heating the fixing member;
A pressure that is movable between a pressure position that pressurizes the fixing member and a position that is spaced apart from the fixing member, and that allows the recording material to pass between the fixing member when the pressure is at the pressure position. Members,
A mover for moving the pressure member between the pressure position and the separation position;
Prior to toner image formation by the toner image forming device, the magnetic field generator generates the AC magnetic field when the pressure member is in the separated position, and the fixing member can fix the toner image. When the heating member is heated to a predetermined temperature lower than the fixing temperature, the pressing member is temporarily moved to the pressing position, and then the pressing member is returned to the separated position. When heated to the fixing temperature, the pressure member is moved to the pressure position to start the toner image formation by the toner image forming device, and the toner image forming device precedes the toner image formation. Then, when the pressure member is in the separated position, the magnetic field generator generates the AC magnetic field, and the fixing member is set to a predetermined temperature lower than a fixing temperature at which the toner image can be fixed. When heated, the pressure member is Is moved to the position, a control unit used depending a second heating to initiate the formation of the toner image and the fixing member is heated to a fixing temperature by the toner image forming device to the operating conditions,
An image forming apparatus comprising:   The control unit selectively uses the first heating and the second heating according to the thickness of the recording material, and performs the second heating on the recording material thicker than the recording material on which the first heating is performed. The image forming apparatus according to claim 1, wherein the image forming apparatus is executed.   The control unit selectively uses the first heating and the second heating according to a power supply voltage, and causes the second heating to be executed under a power supply voltage lower than the power supply voltage at which the first heating is executed. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.   The control unit uses the first heating and the second heating properly according to the environmental temperature, and causes the second heating to be executed under an environmental temperature lower than the environmental temperature at which the first heating is executed. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided.   The control unit selectively uses the first heating and the second heating according to the member temperature of the fixing member before heating, and the first heating is performed under a member temperature higher than a member temperature at which the first heating is performed. The image forming apparatus according to claim 1, wherein two heating is performed.   The control unit selectively uses the first heating and the second heating according to the gloss after the toner image is fixed, and causes the second heating to be executed for a gloss higher than the gloss for which the first heating is performed. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. On the computer,
A toner image forming device that forms a toner image on a recording material, and a fixing member that is heated by electromagnetic induction and contacts the recording material on which an unfixed toner image is formed, and fixes the toner image to the recording material with heat And a magnetic field generator that generates an alternating magnetic field for electromagnetically heating the fixing member, a pressurizing position that pressurizes the fixing member, and a spaced position that is spaced apart from the fixing member. A pressure member through which the recording material passes between the fixing member when in the pressure position, and a mover that moves the pressure member between the pressure position and the separation position. Control the image forming device
Prior to toner image formation by the toner image forming device, the magnetic field generator generates the AC magnetic field when the pressure member is in the separated position, and the fixing member can fix the toner image. When the heating member is heated to a predetermined temperature lower than the fixing temperature, the pressing member is temporarily moved to the pressing position, and then the pressing member is returned to the separated position. First heating for moving the pressure member to the pressure position and starting the toner image formation by the toner image forming device when heated to the fixing temperature;
Prior to toner image formation by the toner image forming device, the magnetic field generator generates the AC magnetic field when the pressure member is in the separated position, and the fixing member can fix the toner image. When the fixing member is heated to a predetermined temperature lower than the fixing temperature, the pressing member is moved to the pressing position, and when the fixing member is heated to the fixing temperature, the toner image forming device Second heating to initiate formation;
According to the operation status of the image forming apparatus.

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