JP2006133317A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus capable of enhancing energy efficiency and shortening a warm-up time by accumulating generated heat, and to provide an image forming apparatus. <P>SOLUTION: Regarding the fixing apparatus 4 provided with a heat source 23, a heat transfer member 24 which is heated by the heat source 23, a pressure member 25 which is brought in press contact with the heat transfer member 24 and a housing 30 where at least the heat source 23 and the heat transfer member 24 are stored, respectively, the housing 30 is constituted so that it may be switched between a tightly closed state where the inside of the housing 30 is shielded from the outside and the heat transfer between the inside of the housing 30 and forced convection C generated outside the housing 30 is interrupted and an open state where at least a part of the housing 30 is opened and the heat transfer between the inside of the housing 30 and the forced convection C generated outside the housing 30 is performed, and in the case of an execution mode of fixing a toner image by heating and pressurizing while making a recording body X pass through a nip part 34 whose temperature is enough to fix the toner image on the recording body X, the housing 30 becomes an open state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device built in an electrophotographic image forming apparatus such as a laser printer, a laser fax machine, or a digital copying machine, and an image forming apparatus provided with the fixing device.

  In an electrophotographic image forming apparatus, the surface of a photosensitive drum is charged almost uniformly, and then the photosensitive drum is exposed by a laser scanning unit or the like to form an electrostatic latent image corresponding to an image signal. Then, the toner charged by the developing device is supplied onto the photosensitive drum to be visualized, and the toner image is transferred to a recording material such as transfer paper. Since the toner image transferred to the recording medium is only carried on the recording medium and is not fixed, the toner image is heated and pressurized by a fixing device provided in the image forming apparatus, and the toner image is melted by heat. An image fixed on the recording medium is formed by fixing.

  As a basic structure of a conventional fixing device, a structure in which a heat roller with a built-in halogen lamp, a press roller pressed against the heat roller, and a thermistor for detecting the temperature of the heat roller are provided inside the housing. It is made up of. According to this fixing device, the toner image passing through the nip portion formed by press-contacting the heat roller and the press roller is heated by the heat of the heat roller heated by the radiant heat of the halogen lamp, Pressure is applied by pressing with a press roller, and the toner is fixed on the recording medium. The housing is formed with a carry-in port through which the recording body is carried in and a carry-out port through which the recording body is carried out, and the recording body carrying the toner image is carried into the housing from the carry-in port and fixed from the carry-out port. The already-recorded body is carried out of the housing (see, for example, Patent Document 1).

  By the way, the storage temperature of toner (thermoplastic resin powder) used to form a toner image used in an electrophotographic image forming apparatus is about 50 ° C. to 70 ° C. or less, and the toner case or the like becomes higher than the storage temperature. In addition, the fluidity is deteriorated, the conveyance characteristics are deteriorated, and the sticking occurs, which causes a failure of the apparatus. In addition, the laser scanning unit is equipped with a resin lens, a laser diode, etc., but the shape and refractive index of the resin lens may change due to temperature rise, and the laser diode may cause oscillation failure at high temperatures. Therefore, when the laser scanning unit is exposed to a high temperature, the optical characteristics may deteriorate. Furthermore, when other components inside the image forming apparatus are also exposed to high temperatures, the component characteristics may be deteriorated.

  On the other hand, the temperature at which the toner image is thermally melted is about 150 ° C. to 200 ° C. When the toner image is fixed, it is necessary to heat the nip portion to the above temperature (fixing temperature). When the temperature is heated to the fixing temperature, the inside of the image forming apparatus may be heated to a high temperature state by radiation, heat transfer, convection, or the like from the fixing device. Therefore, conventionally, an image forming apparatus has a built-in fan or the like, and the inside of the image forming apparatus is cooled by generating forced convection particularly around the fixing device by the fan or the like.

2. Description of the Related Art In recent years, there has been provided an image forming apparatus that can save energy by controlling the temperature of a fixing device at a low temperature during standby or by lowering the temperature to room temperature. However, in the case of a large machine, the fuser becomes larger and its heat capacity increases, so the waiting time or the time required to heat from room temperature to the fixing temperature (warm-up time) becomes longer, and the waiting time until the start of use becomes longer. become longer. Therefore, a method of shortening the heating time by reducing the heat capacity such as thinning the heat roller of the fixing device has been proposed.
JP 2004-13024 A

  However, in the fixing device provided in the above-described conventional image forming apparatus, since the carry-in port and the carry-out port through which the recording body is carried in and out are formed in the case, it is generated around the case by a fan or the like. The forced convection that has passed passes through the vicinity of the carry-in inlet and the carry-out port, heat transfer is performed between the inside of the housing and the forced convection, and the heat in the housing is taken away by the forced convection. In other words, when the fixing device is heated to the fixing temperature, the inside of the housing is simultaneously performed by the heating by the halogen lamp and the cooling by the forced convection, resulting in poor energy efficiency and a long warm-up time. There is a problem. In addition, during standby, the heat inside the housing is actively taken away by forced convection, so when maintaining the standby temperature at a temperature slightly lower than the fixing temperature, heating by a halogen lamp and cooling by forced convection are required. It will be performed in parallel, and the energy efficiency will deteriorate. In addition, there is a limit in the method of reducing the heat capacity such as thinning the heat roller of the fixing device, and there is a problem that a large heat capacity is required in a recent large-sized image forming apparatus and the warm-up time is long. .

  The present invention has been made in consideration of the above-described conventional problems, and provides a fixing device and an image forming apparatus capable of improving energy efficiency and shortening warm-up time by storing generated heat. The purpose is to do.

  The invention described in claim 1 includes a heat source, a heat transfer member heated by the heat source, a pressure member pressed against the heat transfer member, and a housing in which at least the heat source and the heat transfer member are accommodated. A fixing device for fixing the toner image to the recording body by heating and pressing at a nip portion formed by pressure contact between the heat transfer member and the pressure member while sandwiching and conveying the recording body. The casing has a sealed state in which the inside of the casing is cut off from the outside and heat transfer between the inside of the casing and the forced convection generated outside the casing is hindered, and at least one of the casings. The nip portion is formed to be switchable between an open state where the portion is opened and heat transfer between the inside of the housing and the forced convection is performed, and the toner image is at a temperature at which the toner image can be fixed to the recording medium. Pass the recording medium and apply heat and pressure Wherein when the execution mode for fixing the toner image that, the housing is characterized by comprising the open state.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, when the temperature of the nip portion is increased to a level equivalent to the fixing temperature or maintained at a temperature similar to the fixing temperature. The housing is in the sealed state.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a standby mode in which the temperature of the nip portion is increased or decreased to a predetermined standby temperature or maintained at the standby temperature is the fixing temperature. The plurality of standby modes include a first standby mode for opening the housing and a first standby mode for closing the housing. It is characterized by being roughly divided into two standby modes.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the casing is in a sleep mode in which the temperature of the nip portion is cooled to or maintained at about room temperature. Is characterized by being in the open state.

  According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising: an image forming unit that electrostatically transfers a toner image to a recording body; and a forced convection generation unit that generates forced convection around at least the casing. A fixing device according to claims 1 to 4 is provided.

  According to the fixing device of the first aspect of the present invention, the housing includes a sealed state in which the inside of the housing is blocked from the outside and heat transfer between the inside of the housing and forced convection is inhibited, and the housing Since at least a part of the housing is open and can be switched to an open state in which heat transfer between the inside of the housing and forced convection is performed, when the housing is in a sealed state, Heat transfer is obstructed, and heat generated inside the housing can be stored without being deprived of forced heat by the forced convection. As a result, heating can be performed effectively, temperature drop when the heat source is turned off can be suppressed, energy efficiency can be improved, and warm-up time can be shortened. Further, at least in the execution mode, the casing is opened, so that the recording medium carrying the toner image can be taken into the casing and the recording medium on which the toner image is fixed is sent out of the casing. Can do.

  According to the fixing device described in claim 2 of the present invention, since the casing is in a sealed state in the preparation mode, heat transfer between the casing and the forced convection is hindered, The heat is not deprived by forced convection and can be heated efficiently until the fixing temperature is reached, and the warm-up time can be shortened. In addition, when the operation mode is switched to the preparation mode after the execution mode, the heat inside the housing is efficiently stored, so that when the operation mode is switched again to the execution mode, it can be heated to the fixing temperature in a short time.

  According to the fixing device described in claim 3 of the present invention, there are a plurality of standby modes stepwise within a temperature range lower than the fixing temperature and higher than the room temperature. Since it is roughly divided into a first standby mode that opens the body and a second standby mode that closes the housing, heat is stored in the housing in the second standby mode, and the efficiency In the first standby mode, the heat in the housing is taken away by heat transfer with forced convection, and the inside of the housing can be efficiently cooled.

  According to the fixing device described in claim 4 of the present invention, since the casing is in an open state in the sleep mode, the heat in the casing is taken away by heat transfer with forced convection, which is efficient. Thus, the inside of the housing can be cooled and temperature rise can be suppressed.

  According to the image forming apparatus described in claim 5 of the present invention, it is possible to provide an image forming apparatus with high energy efficiency and a short warm-up time.

  The first, second, and third embodiments of the fixing device and the image forming apparatus according to the present invention will be described below with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic diagram illustrating a schematic configuration of a main part of the image forming apparatus 1.
As shown in FIG. 1, in the image forming apparatus 1 according to the present embodiment, a toner image is electrostatically transferred to a transport unit 2 and a sheet (recording member) X such as paper disposed on the transport unit 2. A plurality of image forming units (image forming means) 3M, 3Y, 3C, and 3BK, and a fixing device that fixes and fixes (fixes) a toner image carried on the sheet X to the sheet X while nipping and conveying the sheet X A (fixing device) 4 and a fan (forced convection generating means) 5 that generates forced convection C inside the image forming apparatus 1 and suppresses temperature rise in the image forming apparatus 1 are provided.

Here, the image forming units 3M, 3Y, 3C, and 3BK will be described in advance.
The image forming units 3M, 3Y, 3C, and 3BK are formed by exposure by charging a photosensitive drum (image carrier) 6 and scanning the surface of the charged photosensitive drum 6 with a laser beam 11 to perform exposure. The latent image is developed, and a developed image (toner image) formed by the development is transferred onto a sheet X conveyed by a transfer belt 10 described later. Here, the plurality of image forming units 3M, 3Y, 3C, and 3BK are sequentially arranged in the transfer direction along a transfer belt 10 to be described later, and the most upstream side based on the transfer direction of the transfer belt 10 To magenta, yellow, cyan, and black toner images. The image forming units 3M, 3Y, 3C, and 3BK are provided with a photosensitive drum 6, an exposure device (exposure unit) 7, a developing device (development unit) 8, a charging roller 9, and a cleaning unit 19, respectively.

The photosensitive drum 6 is an example of an image carrier, and rotates about the direction of the arrow shown in FIG. 1. The photosensitive drum 6 is irradiated with the laser beam 11 from the exposure device 7 to form a latent image on the surface.
The exposure device 7 scans the laser beam 11 focused on a minute spot in a fixed direction on a straight line parallel to the rotation axis of the photosensitive drum 6 at the exposure position on the photosensitive drum 6.

  The developing device 8 develops the latent image to form a toner image, and triboelectrically charges the toner of a powder having a predetermined color so as to be negatively charged. Toner is supplied to the exposed portion of the photosensitive drum 6 having a relatively positive potential, and the toner adheres to the surface of the photosensitive drum 6. In the developing device 8, toner, a stirrer 12d that stirs and charges the toner, a supply roller 12c that conveys the charged toner to the developing roller 12a side, and a toner that is supplied by the supply roller 12c are electrified and charged. A developing roller 12a that adheres to the surface with the Coulomb force generated by the toner and conveys it to the vicinity of the photosensitive drum 6 and a developing blade 12b for regulating the toner layer thickness on the developing roller 12a are provided.

  The cleaning unit 19 contacts the photoconductive drum 6 and removes the toner on the surface of the photoconductive drum 6. The cleaning unit 19 is disposed near the cleaning roller 19 a and collects the toner removed by the cleaning roller 19 a. And a box (not shown).

  The charging roller 9 is for setting the surface potential of the photosensitive drum 6 to a predetermined potential at the time of image formation. The roller portion is constituted by an elastic body imparted with conductivity to the metal shaft, and downstream of the photosensitive drum cleaning roller 19. It contacts with the photosensitive drum 6 at the charging position on the side. The charging roller 9 is pressed against the photosensitive drum 6 with a predetermined pressure by pressing a bearing (not shown) by a biasing means such as a spring. As a result, the roller portion is deformed to form a nip portion that contacts the photosensitive drum 6 with a predetermined width in the circumferential direction, and when a DC voltage is applied to the charging roller 9, the surface of the photosensitive drum 6 is set to a predetermined potential. Can be charged. Further, a charging roller cleaning roller 21 is in contact with the charging roller 9 so as to remove dirt on the surface of the charging roller 9.

  Next, the transport unit 2 will be described. The transport unit 2 includes an endless transfer belt 10 that is circulated and moved in one direction by driven rollers 13 a, 13 b, 13 c and a tension roller 14 disposed on the inner peripheral portion, and an outer peripheral side of the transfer belt 10. A driving roller 15 that is pressed toward the driven roller 13a via the transfer belt 10, a transfer roller 16a that is held so that the transfer belt 10 is brought into contact with the photosensitive drum 6 at the transfer position, and a cleaning blade on the transfer belt 10. And a belt cleaning unit 17 having a space for scraping off deposits on the surface of the transfer belt 10 and collecting the scraped deposits.

The driving roller 15 is pressed toward the driven roller 13a by an urging means such as a spring. When the driving roller 15 is rotationally driven by a driving means (not shown), the transfer belt 10 sandwiched between the driving roller 15 and the driven roller 13a is circulated and moved in the direction of the arrow shown.
The material of the transfer belt 10 is such that when the sheet X is opposed to the photosensitive drum 6 with the sheet X interposed therebetween, the toner on the photosensitive drum 6 can be attracted by the transfer voltage applied to the transfer roller 16a contacting the back surface. A body sheet is used. Further, the transfer belt 10 has a light reflection characteristic for reflecting light.

The transfer roller 16a has a roller portion made of, for example, conductive or semi-conductive synthetic rubber on a metal rotation shaft, and a transfer high-voltage power supply (not shown) is connected to the rotation shaft. The surface potential of the part is controlled.
Here, the transfer roller 16a and the control unit 16 that controls the surface potential of the roller unit cause the visible image formed by the image forming units 3M, 3Y, 3C, and 3BK to be conveyed on the transfer belt 10 by the sheet X. A transfer unit 18 that electrostatically transfers the toner image is configured.

  Next, the fixing device 4 will be described. The fixing device 4 is disposed at the front of the transport unit 2 and is installed on a fixed base 22 formed in the image forming apparatus 1.

  FIGS. 2A and 2B are both schematic views showing the configuration of the fixing device 4, and FIG. 3 is a perspective view of the end portion of the fixing device 4. As shown in FIGS. 2A, 2B, and 3, the fixing device 4 includes a rod-shaped heat source 23, a round tubular heat transfer member 24 heated by the heat source 23, and a heat transfer member 24. A pressure member 25 having a cylindrical shape that is in pressure contact with it, a temperature control device (temperature control means) 26 for controlling the temperature of the heat transfer member 24, and a heat source 23 at a predetermined temperature by sensing the temperature inside a housing 28 described later. A safety device (temperature rise suppression means) 27 that forcibly turns off, a heat source 27, a heat transfer member 24, a pressure member 25, a temperature control device 26, and a safety device 27 are housed, and the sheet X is carried in and out. A box-shaped housing 30 formed with a carry-in port 28 and a carry-out port 29, a closing member 31 for closing the carry-in port 28 and the carry-out port 29, and an opening / closing mechanism 32 for opening and closing the two closing members 31, respectively. , Conveying the sheet X through the pressure member 25 And a drive mechanism 33 for pivoting is provided countercurrent.

  The heat source 23 is made of, for example, a halogen lamp or the like, and a main body portion 23 a that generates heat is inserted from one end side of the tubular heat transfer member 24 to the approximate center inside thereof. Further, the base portion (base end portion) 23b of the heat source 23 is provided so as to penetrate through one end surface of the housing 30, and is not shown at the end of the base portion 23b protruding outside the housing 30. A lead wire 23c connected to the power supply circuit is connected.

  The heat transfer member 24 is made of a material having excellent thermal conductivity, such as aluminum, stainless steel, or iron, and is heated by radiant heat from the heat source 23. The surface of the heat transfer member 24 is coated with a fluororesin excellent in heat resistance or a modified fluororesin (polytetrafluoroethylene or the like) in order to prevent toner adhesion. Further, the heat transfer member 24 is held so as to be rotatable about the shaft.

  The pressure member 25 is disposed in parallel with the axial direction of the heat transfer member 24 and is disposed so as to face the heat transfer member 24 while being pressed against the heat transfer member 24. The pressure member 25 has a configuration in which a heat resistant elastic layer 25b such as silicon rubber is wound around a metal core material 25a, and the surface of the pressure member 25 is made of fluororesin or fluorine having excellent heat resistance to prevent adhesion. It is coated with a modified resin (for example, polytetrafluoroethylene). The pressure member 25 mechanically pressurizes the heat transfer member 24, and the nip portion 34 is formed by the pressure contact between the heat transfer member 24 and the pressure member 25.

  The sheet X is nipped and conveyed by the heat transfer member 24 and the pressure member 25 described above. When the toner image carried on the sheet X passes through the nip portion 34, the toner image is heated and melted by the heat of the heat transfer member 24, and is pressed by the pressure of the pressing member 25, and is fixed to the sheet X.

  The temperature control device 26 includes a thermistor (temperature sensor) 35 that is disposed on the surface of the heat transfer member 24 and detects the current temperature of the heat transfer member 24, and a heat source based on information on the current temperature detected by the thermistor 35. And a control unit 36 that controls the control unit 23. The thermistor 35 is disposed at a temperature detection point A on the upstream side of the nip portion 34, and the temperature of the temperature detection point A is measured by the thermistor 35. The upstream side means the rear side in the rotation direction of the heat transfer member 24 that rotates the shaft, and the temperature detection point A is within the range of the right half of the heat transfer member 24 in FIGS. 2 (a) and 2 (b). is there. As a temperature control method in the temperature controller 26, the heat source 23 is turned on when the current temperature detected by the thermistor 35 is lower than the set target temperature, while the current temperature detected by the thermistor 35 is set. An on / off method is employed in which the heat source 23 is turned off when the temperature is higher than the target temperature. The target temperature is set in consideration of an error between the temperature at the temperature detection point A and the temperature of the nip portion 34 to be described later. The temperature is set in consideration of an error between the temperature of the temperature detection point A and the temperature of a nip portion 34 described later.

  The safety device 27 has a configuration in which the terminals 27b of the two lead wires 27a are connected via a fusible member 27c. The safety device 27 is interposed in a power supply circuit (not shown) of the heat source 23, and the temperature in the housing 30 is increased. When the temperature rises abnormally, the encapsulated fusible body 27c is melted and the power supply circuit of the heat source 23 is shut off. The temperature at which the fusible body 27c is melted can be appropriately changed. For example, when the fixing temperature E6 is 180 ° C., the set temperature of the safety device 27 is set to 240 ° C. In this case, when the temperature in the housing 30 abnormally rises to 240 ° C., the fusible body 27c is melted and the power source of the heat source 23 is turned off.

  The housing 30 includes a structure 37 formed in a box shape and a heat insulating material 38 provided on the inner surface of the structure 37. The heat insulating material 38 is made of silicon foam containing gas bubbles, and is spread on the inner surface of the structure 37 without any gap. The heat source 23, the heat transfer member 24, and the pressure member 25 housed inside the housing 30. The temperature control device 26 and the safety device 27 are disposed around. As the heat insulating material 38, a silicon foam containing substantially vacuum bubbles may be used.

  The carry-in port 28 and the carry-out port 29 formed in the housing 30 are respectively formed on opposite side surfaces in the longitudinal direction of the housing 30, and the carry-in port 28 is formed on the rear side of the nip portion 34. A carry-out port 29 is formed on the front side of the portion 34. The carry-in port 28 and the carry-out port 29 extend in directions parallel to the axial direction of the heat transfer member 23 and the pressure member 24, respectively. Thin plate-like guides 39 for guiding the conveyed sheet X are attached to the upper and lower ends of the carry-in entrance 28 and the carry-out exit 29, respectively. The guides 39 provided at the upper ends of the carry-in entrance 28 and the carry-out exit 29 are respectively installed obliquely downward from the upper ends of the carry-in entrance 28 and the carry-out exit 29, and provided at the lower ends of the carry-in entrance 28 and the carry-out exit 29. The guide 39 is installed obliquely upward from the lower ends of the carry-in entrance 28 and the carry-out exit 29.

  As with the case 30 described above, the closing member 31 is a silicon foam containing gas bubbles provided on the inner surface of the plate-like structure 40 and the structure 40 facing the carry-in port 28 and the carry-out port 29. It is comprised from the heat insulating material 41 which consists of. Further, the closing member 31 is formed larger than the carry-in port 28 and the carry-out port 29 and is held so as to be slidable in the vertical direction while being in close contact with the side surface of the housing 30. In addition, as the heat insulating material 41, a silicon foam containing substantially vacuum bubbles may be used.

  The opening / closing mechanism 32 that opens and closes the closing member 31 is a mechanism that moves the closing member 31 up and down to open and close it. As the opening / closing mechanism 32, for example, a mechanism capable of appropriately stopping the closing member 31 and adjusting the opening degree (opening degree) of the closing member 31 such as a mechanism using a rack and a pinion or a cam mechanism is preferable. A mechanism that selectively selects whether the closing member 31 is opened or closed, such as a mechanism using a spring or a solenoid mechanism, may be used. The opening / closing mechanisms 32 are provided on both sides of the closing member 31 so as to sandwich the closing member 31, and the opening / closing mechanisms 32 on both sides are driven synchronously.

  When the closing member 31 is opened / closed by the opening / closing mechanism 32, the housing 30 is blocked from the outside by the forced convection C as shown in FIG. And a closed state in which heat transfer between the housing 30 and the forced convection C is performed by opening both side surfaces of the housing 30 as shown in FIG. Can be switched to. That is, when the closing member 31 is closed, the inside of the housing 30 is in a sealed state, and when the closing member 31 is opened, the inside of the housing 30 is in an open state.

  As shown in FIG. 3, the drive mechanism 33 is engaged with the first gear 42 provided at the end of the heat transfer member 24 and the first gear 42 provided at the end of the pressure member 25. The second gear 43 and a transmission unit 45 that transmits the power of the power source 44 built in the image forming apparatus 1 to the pressing member 25 are configured. The power source 44 is a gear that is rotated by a gear 46, a belt 47, and the like disposed in the image forming apparatus 1. The transmission unit 45 is disposed in the housing 30 and meshed with the second gear 43, and the fourth gear 49 disposed outside the housing 30 and meshed with the power source 44. The shaft 30 includes a shaft member 50 penetrating through one end face of the housing 30 so as to be axially rotatable and connecting the third gear 48 and the fourth gear 49. The shaft member 50 is interposed between the center portion of the third gear 48 and the center portion of the fourth gear 49, and the power of the fourth gear 49 is transmitted through the shaft member 50 to the third gear. 48.

Next, the fan 5 that cools the inside of the image forming apparatus 1 will be described.
As shown in FIG. 1, the fan 5 is installed around the fixing device 4, and generates forced convection C particularly around the housing 30. When the casing 30 is exposed to the forced convection C, the heat of the casing 27 is cooled by the heat transfer with the forced convection C. Further, as shown in FIGS. 2A and 2B, when the closing member 31 is opened and the housing 30 is in the open state, the housing 30 and the forced convection C transfer heat to the housing. The heat inside the body 30 is taken away and the inside of the housing 30 is cooled.

  Next, the operation of the above-described fixing device 4 will be described. FIG. 4 is a flowchart showing the operation of the fixing device 4, and FIG. 5 is a table showing the temperature change of the fixing device 4, and is a table showing an example of the operation of the fixing device 4.

  As shown in FIGS. 2A, 2B, 4 and 5, the operation state of the fixing device 4 includes a preparation mode R prepared for operating the fixing device 4 and a short operation time. Standby modes W1, W2, W3, and W4 for waiting in a ready state, a sleep mode S in which the function of the image forming apparatus 1 is stopped, and an execution mode for fixing the toner image on the sheet X by operating the fixing device 4 There is P.

Here, first, each mode will be described.
The preparation mode R is a state in which the temperature of the nip portion 34 is raised to a temperature (preparation temperature) E5 that is approximately equal to the fixing temperature E6 or is maintained at the preparation temperature E5. The preparation temperature E5 is a temperature range that can be immediately adjusted (in about 1 to 2 seconds) to the fixing temperature E6, for example, in the range of (fixing temperature E6-70 ° C.) to (fixing temperature E6-30 ° C.). is there. In the preparation mode R, both the closing members 31 are closed, and the inside of the housing 30 is in a sealed state. Further, in the preparation mode R, the target temperature of the temperature control device 26 is set on the basis of the fixing temperature E6 in consideration of an error between the temperature at the temperature detection point A and the temperature of the nip portion 34.

  The standby modes W1, W2, W3, and W4 are states in which the temperature of the nip portion 34 is increased or decreased to a predetermined standby temperature E1, E2, E3, E4, or maintained at the standby temperatures E1, E2, E3, E4. . In the standby modes W1, W2, W3, W4, a plurality of standby temperatures E1, E2, E3, E4 are set in stages, and the standby temperatures E1, E2, E2, E3, W4 of the standby modes W1, W2, W3, W4 are set. E2, E3, and E4 are set within a temperature range that is lower than the fixing temperature E6 and higher than the room temperature E0. In the standby modes W1, W2, W3, and W4, the target temperature of the temperature control device 26 is determined based on the set standby temperatures E1, E2, E3, and E4, and the temperature of the temperature detection point A and the temperature of the nip portion 34. Set with error in mind.

  Further, the plurality of standby modes W1, W2, W3, and W4 include the first standby modes W1 and W2 that open both the closing members 31 to open the inside of the housing 30, and the both blocking members 31. They are roughly divided into second standby modes W3 and W4 that are closed and the inside of the housing 30 is sealed. The standby temperatures E1 and E2 of the first standby modes W1 and W2 are lower than the standby temperatures E3 and E4 of the second standby modes W3 and W4. That is, in the standby modes W3 and W4 in which the standby temperatures E3 and E4 are higher than a certain temperature, both the closing members 31 are closed and the inside of the housing 30 is sealed, and the standby temperatures E1 and E2 are constant. In the standby modes W1 and W2 that are lower than the above temperature, both the closing members 31 are opened, and the inside of the housing 30 is opened. At this time, only one of the both closing members 31 may be opened to open the housing 30, and at least one of the both closing members 31 may be opened.

  The sleep mode S is a state in which the temperature of the nip portion 34 is cooled to about room temperature E0 or maintained at about room temperature E0. In the sleep mode S, both the closing members 31 are opened, and the inside of the housing 30 is in an open state. Further, in the sleep mode S, the heat source 23 is turned off and the heat source 23 is turned off, and the temperature control device 26 is also deactivated and is not operating. At this time, only one of the both closing members 31 may be opened to open the housing 30, and at least one of the both closing members 31 may be opened.

  In the execution mode P, the sheet X is passed through the nip portion 34 heated to the fixing temperature E6, and the toner is heated by the heat of the heat transfer member 24 and pressed by the pressure contact between the heat transfer member 24 and the pressure member. In this state, the image is fixed. In the execution mode P, both the closing members 31 are opened, and the inside of the housing 30 is opened. The closing member 31 only needs to be opened when the sheet X passes through the carry-in entrance 28 and the carry-out exit 29. For example, at the beginning of the execution mode P, the closing member 31 on the carry-out exit 29 side is closed. The closing member 31 on the carry-out port 29 side is opened when the fixed sheet X is carried out from the carry-out port 29, and when the sheet X passes through the carry-in port 28, the closing member 31 on the carry-in port 28 side is opened. You may close it.

  Further, when the main power supply of the image forming apparatus 1 is turned off, the function of the fixing device 4 is stopped, and the temperature of the nip portion 34 is cooled to about room temperature E0 or maintained at about room temperature E0. Become. At this time, both the closing members 31 are opened, and the inside of the housing 30 is opened. Further, the power source of the heat source 23 is turned off and the heat source 23 is turned off, and the temperature control device 26 is also deactivated and is not operating. At this time, only one of the both closing members 31 may be opened to open the housing 30, and at least one of the both closing members 31 may be opened.

Next, the operation of the fixing device 4 will be specifically described.
First, when the main power of the image forming apparatus 1 is turned on, the fixing device 4 enters the standby mode W4, and the nip portion 34 having a temperature of about room temperature E0 is heated to the highest standby temperature E4 by heating from the heat source 23. In addition, the temperature is adjusted so as to be maintained at the standby temperature E4. The temperature adjustment is performed using the temperature control device 26, and the heat source 23 is switched on and off as necessary. At this time, both the closing members 31 are closed, and the inside of the housing 30 is sealed.

  Next, when the image forming apparatus 1 is operated to prepare for the start of use, the fixing device 4 in the standby mode W4 is switched to the preparation mode R. At this time, the nip portion 34 is heated to the preparation temperature E5 by heating from the heat source 23, and the preparation temperature E5 is maintained by the temperature control device 26. At this time, both the closing members 31 remain closed, and the inside of the housing 30 is sealed.

  Next, when the image forming apparatus 1 is operated and printing is started, the fixing device 4 is switched to the execution mode P. At this time, the nip portion 34 is heated to the fixing temperature E6 by heating from the heat source 23, and the fixing temperature E6 is maintained by the temperature control device 26. At this time, both the closing members 31 are opened, and the sheet X carrying the toner image is conveyed from the carry-in entrance 28 into the housing 30, and the fixed sheet X that has passed through the nip portion 34 is fed from the carry-out exit 29. It is conveyed outside the housing 30.

  When printing is completed, the fixing device 4 switches to the preparation mode R. When the mode is switched to the preparation mode R, the heat source 23 is turned off and the temperature of the nip portion 34 is lowered to the preparation temperature E5. Then, the preparation temperature E5 is maintained by the temperature control device 26. Thereafter, when an operation to perform printing is performed subsequently, the fixing device 4 switches again to the execution mode P described above, and both the closing members 31 are opened to perform the fixing operation. On the other hand, after switching to the preparation temperature E5, printing is not continued and when the predetermined mode switching time T1 elapses without the image forming apparatus 1 being operated, the fixing device 4 switches to the standby mode W4. When the mode is switched to the standby mode W4, the heat source 23 is turned off, and the temperature of the nip portion 34 gradually decreases to the standby temperature E4. Then, the standby temperature E4 is maintained by the temperature control device 26.

  After the switching to the standby mode W4, when the predetermined mode switching time T2 has elapsed without the image forming apparatus 1 being operated, the fixing device 4 switches to the standby mode W3 where the standby temperature is one step lower. When the mode is switched to the standby mode W3, the heat source 23 is turned off and the temperature of the nip portion 34 gradually decreases to the standby temperature E3. Then, the standby temperature E3 is maintained by the temperature control device 26. At this time, both the closing members 31 remain closed, and the inside of the housing 30 is sealed.

  After the switching to the standby mode W3, when the predetermined mode switching time T3 elapses without further operation of the image forming apparatus 1, the fixing device 4 switches to the standby mode W2 in which the standby temperature is further lowered. When the mode is switched to the standby mode W2, the heat source 23 is turned off, both the closing members 31 are opened, the inside of the housing 30 is opened, and the temperature of the nip portion 34 is lowered to the standby temperature E2. Then, the standby temperature E2 is maintained by the temperature control device 26.

  After the switching to the standby mode W2, when the predetermined mode switching time T4 elapses without further operation of the image forming apparatus 1, the fixing device 4 switches to the standby mode W1 in which the standby temperature is further lowered. When the mode is switched to the standby mode W1, the heat source 23 is turned off, and the temperature of the nip portion 34 is lowered to the standby temperature E1. Then, the standby temperature E1 is maintained by the temperature control device 26. At this time, both the closing members 31 are left open, and the inside of the housing 30 is open.

  After the switching to the standby mode W1, the fixing device 4 switches to the sleep mode S when a predetermined mode switching time T5 elapses without further operation of the image forming apparatus 1. When the mode is switched to the sleep mode S, the heat source 23 is turned off, and the temperature of the nip portion 34 is lowered to the room temperature E0. At this time, both the closing members 31 are left open, and the inside of the housing 30 is open.

  In addition, as shown in FIG. 4, when the image forming apparatus 1 is operated and preparations for starting use are made in each of the standby modes W1, W2, W3, W4 and the sleep mode S, the standby mode W4 is set. A certain fixing device 4 is switched to the preparation mode R, both the closing members 31 shown in FIG. 2 are closed, and the nip 34 is heated to the preparation temperature E5 and maintained at the preparation temperature E5.

FIG. 6 is a table showing a temperature change of the fixing device 4, and is a table showing an example of the operation of the fixing device 4 at the time of abnormality.
As shown in FIG. 6, the temperature inside the fixing device 4 may rise abnormally. In such a case, when the temperature inside the fixing device 4 reaches the set temperature (fuse temperature E7) of the safety device 27, the safety device 27 is activated. When the safety device 27 is activated, the power source of the heat source 23 is forcibly turned off, and the temperature inside the fixing device 4 gradually decreases. At this time, when both of the blocking members 31 are opened, the cooling is effectively performed.

  According to the fixing device 4 and the image forming apparatus 1 having the above-described configuration, the housing 30 is formed so as to be switchable between a sealed state and an open state. Heat transfer between the convection C and the forced convection C is inhibited, and the heat generated in the housing 30 can be stored without the heat in the housing 30 being taken away by the forced convection C. As a result, heating can be performed effectively, temperature drop when the heat source 23 is turned off can be suppressed, energy efficiency can be improved, and warm-up time can be shortened. At least in the execution mode P, the housing 30 is opened, so that the sheet X carrying the toner image can be taken into the housing 30 and the sheet X to which the toner image is fixed is housed. It can be sent out of the body 30.

  Moreover, since the housing | casing 30 will be in a sealing state at the time of the preparation mode R, the heat transfer between the housing | casing 30 and forced convection C is inhibited, and the heat | fever inside a housing | casing 30 is not taken by forced convection, Heating can be efficiently performed until the fixing temperature E6 is reached, and the warm-up time can be shortened. Further, when the mode is switched to the preparation mode R after the execution mode P, the heat inside the housing 30 is efficiently stored. Therefore, when the mode is switched again to the execution mode P, the heat can be heated to the fixing temperature E6 in a short time.

  Further, the operation state of the fixing device 4 includes a plurality of standby modes W1, W2, W3, W4 stepwise within a temperature range lower than the fixing temperature E6 and higher than the room temperature E0. Since W2, W3, and W4 are broadly divided into first standby modes W1 and W2 that make the housing 30 open, and second standby modes W3 and W4 that make the housing 30 sealed, the second In the standby modes W3 and W4, heat is stored in the housing 30 and the temperature can be maintained efficiently. In the first standby modes W1 and W2, the heat in the housing 30 is forced. It is taken away by heat transfer with the convection C, and the inside of the housing 30 can be efficiently cooled.

  In addition, when the sleep mode S and the main power supply of the image forming apparatus 1 are turned off, the housing 30 is in an open state, so that heat in the housing 30 is taken away by heat transfer with the forced convection C, which is efficient. Thus, the inside of the housing 30 can be cooled, and the temperature rise inside the image forming apparatus 1 can be suppressed.

  Further, the fixing device 4 accommodates a housing 30 in which a heat source 23, a heat transfer member 24, and a pressure member 25 are respectively housed, and a carry-in port 28 and a carry-out port 29 for carrying in and out the sheet X are formed, and a carry-in unit Since the closing member 31 that respectively closes the mouth 28 and the outlet 29 and the opening / closing mechanism 32 that opens and closes the closing member 31 are provided, when the closing member 31 is closed, the inside of the housing 30 and the forced convection C Heat transfer is hindered, and heat generated in the housing 30 can be stored without the heat in the housing 30 being taken away by the forced convection C. Thereby, energy efficiency can be improved and warm-up time can be shortened. Further, in the execution mode P, when the closing member 31 attached to the carry-in entrance 28 is opened, the sheet X can be taken into the housing 30 from the carry-in entrance 28, and the closing member 31 attached to the carry-out exit 29. Is opened, the sheet X can be sent out of the housing 30 from the carry-out port 29.

  Moreover, since the heat insulating material 38 is installed around the heat source 23 and the heat transfer body 24, the heat in the housing 30 passes through the housing 30 and is radiated to the outside due to the heat insulating performance of the heat insulating material 38. And energy efficiency can be further improved.

  Further, since the silicon foam containing gas bubbles or substantially vacuum bubbles is used as the heat insulating material 38, the heat resistance of the housing 30 is ensured and the heat insulating performance of the housing 30 is increased, and the inside of the housing 30 is increased. Can be reduced from passing through the housing 30 and being radiated to the outside, and energy efficiency can be improved.

  Moreover, since the heat insulating material 38 is provided inside the structure 39, the amount of heat transferred to the structure 39 is reduced, and deterioration of the structure 39 due to heat can be suppressed.

[Second Embodiment]
Next, a second embodiment will be described. Note that in the second embodiment, description of portions having the same configuration as in the first embodiment is omitted.

  FIGS. 7A and 7B are schematic views showing the configuration of the fixing device 100. As shown in FIGS. 7A and 7B, the closing member 103 that closes the carry-in port 101 and the carry-out port 102 provided in the fixing device 100 is a lower end portion of the closing member 103 by an opening / closing mechanism (not shown). An angle that is held in a vertically rotatable manner around the rotation shaft 104 formed in the direction and is in close contact with the side surface of the housing 104 and parallel to the conveyance direction of the sheet X (in the figure, relative to the side surface of the housing 104) Can be opened and closed up to approximately right angle). As shown in FIG. 7B, the closing member 103 is opened to an angle parallel to the conveyance direction of the sheet X in the execution mode P, and the inner side surface 103a of the closing member 103 is conveyed in the conveyance direction of the sheet X. It is arranged along. The conveyed sheet X is slid on the inner surface 103a of the closing member 103 and guided in a certain direction.

  According to the fixing device 100 configured as described above, in the execution mode P, the opened inner surface of the closing member 103 is arranged along the transport direction of the sheet X, and the conveyed sheet X is moved by the closing member 103. Since the sheet is guided, the sheet X can be reliably conveyed in a predetermined conveyance direction, and the sheet X can be prevented from being jammed.

[Third embodiment]
Next, a third embodiment will be described. In the third embodiment, the description of the parts having the same configurations as those of the first and second embodiments is omitted.

  FIG. 8A and FIG. 8B are schematic views showing the configuration of the fixing device 200. As shown in FIGS. 7A and 8B, the fixing device 200 accommodates a heat source 201, a heat transfer member 202, a temperature control device 203, and a safety device 204, and is an externally disposed heating device. A casing 207 in which an opening 206 is formed to move the pressure member 205 to press contact with the heat transfer member 202 accommodated therein, and a closing member 208 that closes the opening 206 are provided.

  The housing 207 is formed so as to surround the heat source 201 other than the pressurizing member 205, the heat transfer member 202, the temperature control device 203, and the safety device 204. The pressure member 205 is provided outside the housing 207 and is disposed at a position facing the opening 206 of the housing 207. The pressure member 205 is provided so as to be movable up and down, and the fixing device 200 is provided with a moving mechanism 209 that moves the pressure member 205. The moving mechanism 209 includes, for example, a mechanism that uses a rack and a pinion, a cam mechanism, a mechanism that uses a spring, a solenoid mechanism, and the like. This is a mechanism that can be moved toward the heat member 202 and that can move the pressure member 205 to the outside of the housing 207 when the closing member 208 is closed.

  The closing member 208 is composed of two door members 208a and 208b that are opened in a double-opening manner by an opening / closing mechanism (not shown). As shown in FIG. 7B, the closing member 208 is opened to an angle that is parallel to the conveyance direction of the sheet X in the execution mode P, and the inner side surface of the blocking member 208 is the conveyance direction of the sheet X. It is arranged along. The conveyed sheet X is guided in a certain direction by the inner surface of the opened closing member 208.

  Further, in the first standby modes W1 and W2 for opening the inside of the housing 207 and in the sleep mode S, the closing member 208 is opened. At this time, the two door members 208a and 208b may be opened, or only one of the two door members 208a and 208b may be opened.

  According to the fixing device 200 having the above-described configuration, the housing 207 in which the heat source 201 excluding the pressure member 205, the heat transfer member 202, and the like are accommodated and the opening 206 is formed, and the closing member 208 that closes the opening 206 are provided. Therefore, when the closing member 208 is closed, heat transfer between the inside of the housing 207 and the forced convection C is hindered, and the heat inside the housing 207 is not taken away by the forced convection C. 207 can store heat generated inside. Thereby, energy efficiency can be improved and warm-up time can be shortened. In the execution mode P, the closing member 208 is opened, the heat transfer member 202 and the pressure member 205 are brought into pressure contact with each other, and the toner image carried on the sheet X can be fixed. Further, since the pressurizing member 205 is disposed outside the housing 207, the housing 207 itself can be reduced in size, the heat transfer member 202 can be efficiently heated, and the pressurization by heat is performed. Deterioration of the member 205 can be prevented.

  Although the embodiments of the fixing device and the image forming apparatus according to the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention. For example, in the first, second, and third embodiments described above, the casings 30, 104, and 207 are provided with the inlets 28 and 101, the outlets 29 and 102, and the opening 206, and are fixed. The containers 4, 100, and 200 are provided with blocking members 31, 103, and 208 for closing them, but the present invention has two housings as shown in FIGS. 9 (a) and 9 (b). The fixing device 300 may include a housing 301 divided into members 302a and 302b and an opening / closing mechanism (not shown) that moves at least one of the housing members 302a and 302b. The two casing members 302a and 302b are formed in a U-shaped cross-sectional shape, and are sealed when the two casing members 302a and 302b are fitted, and one casing member 302a is illustrated. It is opened by being separated by the opening / closing mechanism. In addition, even if the pressure member is arranged outside the casing as in the third embodiment, by using the casing divided into two casing members, the opening and closing The member can be omitted.

  In the first, second, and third embodiments described above, the casings 30, 104, and 207 include the structure body 37 formed in a box shape and the heat insulating material provided on the inner surface of the structure body 37. As shown in FIG. 10, the present invention includes a heat insulating material 401 formed in a box shape in a fixing device 400 and a holding body 402 that holds the shape of the heat insulating material 401. A housing 403 may be provided. The holding body 402 is formed in a lattice shape on the outer periphery of the heat insulating material 401, and the heat insulating material 401 is provided inside the holding body 402.

  In the first, second, and third embodiments described above, a silicon foam containing gas bubbles or substantially vacuum bubbles is used as the heat insulating material 38. However, in the present invention, ceramics are used as the heat insulating material. May be used. As a result, the heat resistance of the housing itself is ensured, the heat insulation performance of the housing is enhanced, and the heat in the housing is reduced from being radiated to the outside through the housing, thereby improving the energy efficiency. Can do.

  In the present invention, glass wool may be used as a heat insulating material. As a result, the heat resistance of the housing itself is ensured, the heat insulation performance of the housing is enhanced, and the heat in the housing is reduced from being radiated to the outside through the housing, thereby improving the energy efficiency. Can do.

  Further, in the third embodiment described above, in the execution mode P, the pressure member 205 arranged outside the housing 207 moves from the opening 206 into the housing 207, and the heat transfer member in the housing 207. However, in the present invention, in the execution mode, the heat transfer member arranged inside the housing moves from the opening to the outside of the housing and is brought into pressure contact with the pressure member arranged outside the housing. Alternatively, the heat transfer member and the pressure member may be moved and brought into pressure contact with each other.

  In the first, second, and third embodiments described above, the fixing devices 4, 100, and 200 press the roll-shaped heat transfer member 24 and the roll-shaped heating member 25, and these heat transfer members. Fixing is performed by passing the sheet X between the heating member 25 and the heating member 25, but the present invention has a fixing structure in which a flexible belt-like heat transfer member and a pressure member in the form of a roll are pressed against each other. A fixing device comprising a structure in which a cylindrical material made of a soft material is arranged in the vicinity of a roll-shaped heat transfer member, and the cylindrical material is pressed against the heat transfer member from the inside by a pressing member provided in the cylindrical material. It may be a fixing device or a fixing device having another configuration.

  In the first, second, and third embodiments described above, a heat source 23 made of a halogen heater or the like is provided in the heat transfer member 24, and the heat source 23 is spaced from the inner peripheral surface of the heat transfer member 24. Although the heat transfer member 24 is heated by radiant heat from the heat source 23, the present invention uses the magnetic field generation means as a heat source, and provides the magnetic field generation means inside the heat transfer member having a conductive layer. An electromagnetic induction heating type fixing device that generates heat by inducing current by magnetic flux may be used. Further, the present invention may be a fixing device having a configuration in which a heat source is brought into contact with the nip portion of the inner peripheral surface of the heat transfer member to directly heat the heat transfer member, or the heat source is disposed outside the heat transfer member. It may be a fixing device having a configuration in which the heat source is in contact with the outer peripheral surface of the heat transfer member on the upstream side of the nip portion.

In the first, second, and third embodiments described above, the safety devices 27 and 204 are provided in the housings 30, 104, and 207. However, in the present invention, the safety devices 27 and 204 are provided. It may be a case where it is not provided.
In the first, second, and third embodiments described above, the guides 39 are provided at the carry-in ports 28 and 101, the carry-out ports 29 and 102, and the opening 206, respectively. May not be provided.

In the above-described embodiment, the image forming apparatus 1 for color printing including a plurality of image forming units 3M, 3Y, 3C, and 3BK has been described. However, the image forming apparatus according to the present invention includes an image forming unit. May be for monochrome printing provided with only one. The present invention is particularly effective for color printing compatible models that fix a color toner image that is difficult to melt because the fixing nip portion is wide and the heat-melting time can be increased.
The recording body is not limited to the sheet X, and may be a plate-like recording body, and the shape and material of the recording body can be changed as appropriate.

1 is a schematic view of an image forming apparatus for explaining a first embodiment of a fixing device and an image forming apparatus according to the present invention. (A) and (b) are schematic views of the fixing device for explaining the first embodiment of the fixing device and the image forming apparatus according to the present invention, and (a) shows the sealed fixing device. , (B) represents the fixing device in the open state. 1 is a partial perspective view of a fixing device for explaining a first embodiment of a fixing device and an image forming apparatus according to the present invention. FIG. 3 is a flowchart showing the operation of the fixing device for explaining the first embodiment of the fixing device and the image forming apparatus according to the present invention. 6 is a table showing an example of a temperature change in the fixing device at a normal time for explaining the first embodiment of the fixing device and the image forming apparatus according to the present invention. 6 is a table showing an example of a temperature change in the fixing device at the time of abnormality for explaining the first embodiment of the fixing device and the image forming apparatus according to the present invention. (A) and (b) are schematic views of a fixing device for explaining a second embodiment of the fixing device and the image forming apparatus according to the present invention, and (a) represents the hermetically sealed fixing device. , (B) represents the fixing device in the open state. (A) and (b) are schematic views of a fixing device for explaining a third embodiment of a fixing device and an image forming apparatus according to the present invention, and (a) shows a sealed fixing device. , (B) represents the fixing device in the open state. (A) and (b) are schematic views of a fixing device for explaining other embodiments of the fixing device and the image forming apparatus according to the present invention, and (a) shows the sealed fixing device, (B) represents the fixing device in the open state. FIG. 5 is a schematic view of a fixing device for explaining another embodiment of the fixing device and the image forming apparatus according to the present invention.

Explanation of symbols

1 Image forming apparatus 3M, 3Y, 3C, 3BK Image forming unit (image forming means)
4,100,200,300,400 Fixing device (fixing device)
5 Fan (Forced convection generating means)
23, 201 Heat source 24, 202 Heat transfer member 25, 205 Pressure member 30, 104, 207, 301, 403 Housing 34 Nip part X Sheet (recording body)
C Forced convection E0 Room temperature E1, E2, E3, E4 Standby temperature E5 Preparation temperature E6 Fixing temperature P Execution mode R Preparation mode W1, W2 First standby mode (standby mode)
W3, W4 Second standby mode (standby mode)
S Sleep mode

Claims (5)

A heat source, a heat transfer member heated by the heat source, a pressure member pressed against the heat transfer member, and a housing in which at least the heat source and the heat transfer member are respectively housed,
A fixing device that fixes the toner image to the recording medium by heating and pressing at a nip portion formed by pressure contact between the heat transfer member and the pressure member while sandwiching and conveying the recording body;
The casing is sealed with the inside of the casing being blocked from the outside, and the heat transfer between the inside of the casing and the forced convection generated outside the casing is inhibited, and at least a part of the casing Is opened and can be switched to an open state in which heat is transferred between the inside of the housing and forced convection generated outside the housing,
In the execution mode in which the toner image is fixed to the recording medium by heating and pressing the recording medium through the nip portion at a temperature at which the toner image can be fixed to the recording medium. A fixing device which is in an open state. The fixing device according to claim 1.
The fixing device is characterized in that the casing is in the sealed state in a preparation mode in which the temperature of the nip portion is raised to the same level as the fixing temperature or maintained at the same level as the fixing temperature. . The fixing device according to claim 1 or 2,
There are a plurality of standby modes in which the temperature of the nip is increased or decreased to a predetermined standby temperature, or maintained at the standby temperature, stepwise within a temperature range lower than the fixing temperature and higher than room temperature,
The plurality of standby modes are roughly classified into a first standby mode in which the casing is opened and a second standby mode in which the casing is sealed. The fixing device according to any one of claims 1 to 3,
The fixing device is characterized in that the housing is in the open state in a sleep mode in which the temperature of the nip portion is cooled to or maintained at about room temperature. In an image forming apparatus provided with image forming means for electrostatically transferring a toner image to a recording medium and forced convection generating means for generating forced convection at least around the casing,
An image forming apparatus comprising the fixing device according to claim 1.

Images