JP2006072302A - Fixing device and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a heat energy, by directly performing heat absorption and transmission in absorbing heat from a recording medium after fixing and transmitting the heat to a recording medium, before fixing. <P>SOLUTION: A fixing device includes a fixing unit 1, and a heat absorbing and transmitting unit 2 that absorbs the heat of a recording medium 5 sent from the heat unit 1 and transmits the heat thus absorbed to the recording medium 5 to be sent to the fixing unit 1. The heat absorbing and transmitting unit 2 includes a belt member 3 stretched over and circulated around tensile members 4, while it passes through the fixing unit 1. The belt member 3 has a heat absorbing portion HC and a heat transmitting portion HT downstream and upstream from the heat unit 1, respectively. The heat absorbing portion HC contacts the recording medium 5 and absorbs heat in a state that periphery of a contact region is thermally insulated, and the heat transmitting portion HT contacts the recording medium 5 and transmits heat, in a state where the periphery of a contact region is thermally insulated. A drive source 6 for the belt member 3 is also used for other members relating to recording paper conveyance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system or an electrostatic recording system, and an improvement of an image forming apparatus using the same.

Conventionally, as this type of image forming apparatus, each color component toner image formed on a photoconductor or the like is sequentially primary transferred to an intermediate transfer member, and a multicolor toner image on the intermediate transfer member is transferred to a secondary transfer device (collective transfer device). Are known to be batch-transferred onto paper.
In these color image forming apparatuses, demands for speeding up, miniaturization, and energy saving have been strong in recent years. Among them, energy saving technology aimed at reducing the environmental impact of thermal fixing devices that consume the most energy in the image forming process. (Power saving technology) has been required.
In response to such a request, the heat of the fixed paper carried out from the fixing device is directly or indirectly transmitted to the paper before fixing, and the paper is preheated before fixing, which is necessary for the subsequent fixing. Technologies that reduce the heating energy or increase the fixing speed without increasing the heating power have been proposed (see, for example, Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 8-328412 (Example, FIGS. 2 to 15) JP 2000-338803 A (Embodiment of the Invention, FIG. 1)

However, in such a technique, the configuration in which the paper after fixing is brought into direct contact with the paper before fixing is limited to application only when the paper is continuous paper (roll paper), and the paper is cut. In the case of paper, it becomes impossible, and there is a problem that the versatility of applicable paper is lacking.
Further, as shown in FIG. 15, when the fixing device 203 fixes the sheet 202 onto which the toner image of the photosensitive member 201 is transferred, a block is provided between the upstream portion 204 and the downstream portion 205 of the fixing device 203. There has been proposed a system in which a heat pipe 206 is provided to transfer the heat of the sheet 202 after fixing in the downstream portion 205 to the upstream portion 204 (see, for example, Patent Document 1).
An example of such a heat pipe with a block, and furthermore, the heat of the paper after fixing through the heat transfer means such as a heat transfer block, a heat transfer plate, and a combination of a heat transfer roll and a belt. In the configuration in which the sheet is transmitted to the sheet, it is possible to apply a cut sheet, and the versatility of the sheet is ensured. However, the amount of heat in the heat transfer unit becomes steady, and a sufficient heat recovery / heat transfer effect can be obtained. The heat transfer means itself needs to repeatedly rise in temperature due to heat conduction from the paper and approach the paper temperature after fixing. That is, in this configuration, since it takes time to raise the temperature of the heat transfer means, there is a problem that the heating energy for fixing cannot be reduced immediately.

In particular, in such a case, it is difficult to obtain an effect in a small and medium-sized image forming apparatus that frequently performs printing and copying operations of several tens of sheets or less.
Furthermore, a method of adding auxiliary heating to the heat transfer means in an attempt to make the heat recovery / heat transfer effect immediately (make the start-up faster) may consume more energy, which is a good measure for energy saving. It can not be said.

In addition, as shown in FIG. 16, the transfer belt 301 and the sheet conveying belt 302 are arranged to face each other, and a heater 303 is provided inside the transfer belt 301, and the pressure contact plate 304 is provided on both sides (upstream and downstream) of the heater 303. In which the transfer belt 301 and the paper transport belt 302 are pressed against each other, and the paper 305 is transported between the transfer belt 301 and the paper transport belt 302. There has also been proposed to preheat the paper 305 by providing a heat transfer belt 306 that moves in the direction opposite to the direction of movement of the conveyor belt 302 and moving the heat absorption on the downstream side of the heater 303 to the upstream side ( For example, see Patent Document 2).
However, in such a configuration, the configuration is complicated and the heat transfer efficiency is poor because the transport belt for transporting the paper is not a heat transfer medium but uses the heat transfer belt 306 provided separately from the transport belt. Become.

As described above, in each of these prior arts, the heat of the sheet after fixing is merely transmitted indirectly to the sheet before fixing through the heat recovery transmission member.
The present invention is for solving the above-mentioned technical problems. When heat is recovered from a recording material after fixing and heat is transferred to the recording material before fixing, direct heat recovery is transmitted. By doing so, a fixing device with less heating energy and an image forming apparatus using the fixing device are provided.

That is, as shown in FIG. 1, the fixing device according to the present invention recovers the heat of the fixing unit 1 for heating the toner image on the recording material 5 and the recording material 5 sent from the fixing unit 1 to fix the fixing unit. In a fixing device including a heat recovery transmission unit 2 that transmits to a recording material 5 fed to 1, the heat recovery transmission unit 2 is stretched around a plurality of stretching members 4 and bypasses the fixing unit 1 and circulates. The belt member 3 moves, and heat is recovered in a state where the belt member 3 is in contact with the recording material 5 on the downstream side of the fixing unit 1 and insulates the periphery of the region facing the contact portion. A recovery unit HC is provided, and a heat transfer unit HT is provided on the upstream side of the fixing unit 1 so as to transfer heat in a state where the recording material 5 is in contact with the recording material 5 and the area surrounding the contact part is insulated. Drive source 6 Characterized in that it also serves as a drive source 6 of the members involved in the recording material conveyance of.
Therefore, in the prior art, in addition to the conveyance member having the conveyance function of the recording material 5, the heat recovery transmission is indirectly performed using a member having a heat recovery transmission function. The present embodiment is greatly different in that the belt member 3 has a conveyance function for the recording material 5 and a heat recovery transmission function, and directly performs heat recovery transmission.

In such technical means, the fixing device according to the present application is intended for the one that uses the fixing unit 1 when fixing the toner image formed on the recording material 5. At this time, the fixing unit 1 As long as it is promoted for fixing the toner image on the recording material 5, it includes a method for fixing by heating alone, for example, a method using heat and pressure together.
In addition, by using the belt member 3 as the heat recovery transmission unit 2, the contact area with the recording material 5 can be increased, so that efficient heat recovery transmission is possible.

The heat recovery unit HC and the heat transfer unit HT are configured by a contact area between the belt member 3 and the recording material 5, and the heat recovery unit HC effectively recovers the heat so that the recording material 5 before heating is effective. Thus, heat transfer can be performed and thermal efficiency can be improved.
The “state in which the periphery of the area facing the contact portion is thermally insulated” means an aspect in which the belt member 3 and the recording material 5 are insulative by the atmosphere around the contact surface and the belt member 3 is in contact with the heat insulating member. including.

In particular, in the present invention, since the belt member 3 circulates around the fixing unit 1, heat resistance deterioration of the belt member 3 can be suppressed and a longer life can be achieved.
In addition, since the drive source 6 of the belt member 3 is also used as the drive source 6 of other members related to recording material conveyance, the configuration of the fixing device is simplified, the size is reduced, and the drive speed is stabilized. As a result, the conveyance of the recording material in the fixing device becomes stable.
Here, examples of the “members related to other recording material conveyance” include various conveyance members of the fixing unit 1 and the recording material 5. From the viewpoint of further miniaturization / stabilization, the heat recovery transmission unit. It is preferable that the second drive source 6 is also used as the drive source 6 of the fixing unit 1 that is involved in the conveyance of the recording material 5 in the vicinity of the heat recovery transmission unit 2.

Further, it is preferable that the belt member 3 and the fixing unit 1 are connected to and driven by only the gear from the driving source 6 and are configured to be supported and removable independently of each other except the gear. In this case, it is possible to further stabilize the recording material conveyance and to easily work on a jam or the like.
Furthermore, it is preferable that the belt member 3 is set to be driven for a predetermined time before the recording material 5 reaches the heat transfer portion HT. Thus, before the heat transfer to the recording material 5 is performed. In addition, by driving for a predetermined time, for example, the influence of the remaining shape of the belt member 3 can be eliminated. In order to reduce the size of the fixing device, the tension member 4 of the belt member 3 needs to be reduced in size. From this point, the remaining shape of the tension member 4 on the belt member 3 is likely to occur.

Further, from the viewpoint of reducing the remaining shape of the belt member 3, it is preferable to drive the belt member 3 at a predetermined speed for a predetermined time during a period in which the fixing device is on standby.
Furthermore, from the viewpoint of suppressing the remaining shape of the belt member 3, it is preferable to reduce the belt tension after the belt member 3 is stopped. Here, “reducing the belt tension” only needs to make the tension smaller than that during operation, and includes, for example, making the tension zero.

In the belt member 3 according to the present invention, the heat recovery unit HC performs sufficient heat recovery from the recording material 5 to the belt member 3, and maintains sufficient heat energy in the belt member 3, while the heat transfer unit HT. Then, from the viewpoint of sufficient heat transfer to the recording material 5, the heat capacity per unit area of the belt member 3 is preferably set to 450 J / (K · m ² ) or more.

  Furthermore, from the viewpoint of maintaining the heat resistance of the belt member 3 for a long period of time, the belt member 3 is an endless belt made of a heat resistant resin material or a heat resistant rubber material, or an endless belt in which a heat resistant resin material and a heat resistant rubber material are laminated. It is preferable that the heat resistance is about 100 to 120 ° C.

Furthermore, it is preferable that the tension member 4 on which the belt member 3 is stretched is rotatably supported by a support member made of a low thermal conductivity material. In this way, the low thermal conductivity material By using this, it is possible to suppress the heat dissipation from the stretching member 4 and to improve the thermal efficiency during heat recovery transmission. In order to prevent the stretching member 4 from absorbing heat energy collected by the belt member 3, it is preferable to provide a heat insulating layer 4 a on the surface of the stretching member 4.
Furthermore, from the viewpoint of improving thermal efficiency, it is preferable to provide a cover for preventing heat dissipation of the belt member 3 in the movement path of the belt member 3 from the heat recovery unit HC to the heat transfer unit HT.

  Furthermore, in the present invention, from the viewpoint of effectively maintaining the contact between the recording material 5 and the belt member 3 in the heat transfer unit HT and the heat recovery unit HC, the heat transfer unit HT and the heat recovery unit HC have an electrostatic force. It is preferable to provide an electrostatic adsorption device that adsorbs the recording material 5 to the belt member 3. At this time, from the viewpoint of preventing unnecessary charge accumulation on the belt member 3, the two electrostatic adsorption devices disposed in the heat transfer unit HT and the heat recovery unit HC have the charged polarity of the belt member 3 in opposite directions. It is preferable to be configured as follows.

The electrostatic adsorption device provided in the heat transfer unit HT is preferably arranged in a non-contact manner with the toner image surface of the recording material 5 from the viewpoint of eliminating the influence on the toner image surface and maintaining the image quality. In this case, there are an aspect in which the recording material 5 is electrostatically attracted from the toner image surface side by a corona charger, and an aspect in which the bias is applied to the stretching member 4 by applying a bias having a polarity different from the charging polarity of the toner.
On the other hand, as an electrostatic attraction device provided in the heat recovery unit HC, a corona charger that is arranged in a non-contact manner with respect to the recording material 5 or a plate-like or film-like charging member that is arranged in contact with the toner image surface The aspect of this is mentioned. In the embodiment using the plate-like or film-like charging member, from the viewpoint of reducing the frictional force with the recording material 5 and smoothing the feeding of the recording material 5 and preventing the adhesion of foreign matters such as floating toner. A release layer is preferably applied to the surface of the charging member.

  Further, from the viewpoint of stabilizing the adsorption condition of the recording material 5 to the belt member 3, it is preferable that the electrostatic adsorption device is driven at least while the belt member 3 is being driven. In this case, it is possible to prevent a part of the belt member 3 from being abnormally charged up.

  The present invention is intended not only for the fixing device described above but also for an image forming apparatus. In this case, an image forming means for forming a toner image on the recording material 5, A fixing device for fixing the formed toner image, and the fixing device described above may be disposed as the fixing device.

  According to the present invention, a fixing unit that heats a toner image on a recording material, and a heat recovery transmission unit that recovers heat of the recording material sent from the fixing unit and transmits the heat to the recording material sent to the fixing unit are provided. The fixing device includes a belt member that is stretched around a plurality of stretching members and circulates around the fixing unit, and contacts the recording material on the downstream side of the fixing unit and In addition to providing a heat recovery unit that performs heat recovery in a state where the area surrounding the contact area is insulated, the recording medium is in contact with the recording material on the upstream side of the fixing unit and the area surrounding the contact area is insulated. A heat recovery transfer unit provided with a heat transfer unit for heat transfer is provided, and the drive source of the belt member is also used as the drive source of other members related to the conveyance of the recording material. Combines heat recovery transfer function of the transmission function to the recording material, it is possible to perform a direct heat recovery transfer to the recording material efficiently, miniaturization of the apparatus is facilitated. Therefore, compared with the conventional indirect heat recovery transmission method, it is possible to greatly reduce the heating energy at the time of fixing, and it is possible to realize a power saving and downsized fixing device.

  Further, in an image forming apparatus comprising an image forming means for forming a toner image on a recording material and a fixing device for fixing the toner image formed on the recording material, the fixing device described above is provided as the fixing device. In this case, it is possible to provide a power saving and downsized image forming apparatus.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 is a schematic diagram showing the first embodiment of the image forming apparatus to which the present invention is applied.
In the figure, the image forming apparatus according to the present embodiment includes a document reading device 10 that reads a document on a platen 11 and four color components (in this embodiment, yellow, magenta, cyan, black, etc.) by electrophotography. ) The image forming unit 20 (20a to 20d) for forming an image (toner image) and the color component images formed by the image forming units 20 (20a to 20d) are sequentially transferred (primary transfer) and held. Intermediate transfer belt 30, secondary transfer device 31 that collectively transfers (secondary transfer) the superimposed image transferred onto intermediate transfer belt 30 onto a sheet (recording material), and fixes the secondary transferred image onto the sheet A fixing device 70 to be fed, paper feed trays 51 to 53 for supplying papers of various sizes, a paper discharge tray 55 for storing the paper on which toner image formation has been completed, and paper discharge trays 51 to 53 for paper discharge. Those having a plurality of sheet transport path for performing sheet conveyance until Lee 55.

  In the present embodiment, the document reading apparatus 10 includes, for example, a document reading unit 12 disposed below the platen 11 and an ADF (Auto Document Feeder) 13 disposed above the platen 11. The document reading unit 12 irradiates light on a document surface set on the platen 11, a photoelectric conversion element such as a CCD that converts reflected light from the document surface into an electrical signal, and reflected light from the document surface. An appropriate number of mirrors that form paths leading to the photoelectric conversion elements, an imaging lens that forms an image of reflected light from the original surface on the imaging surface of the photoelectric conversion elements, and the like are provided. For this reason, the document reading apparatus 10 reads a document set manually on the platen 11 or a document set via the ADF 13 and converts it into corresponding image data.

Each of the image forming units 20 (20a to 20d) has a photosensitive drum 21, and around each photosensitive drum 21, a charging device 22 such as a charging roll for charging the photosensitive drum 21, a charging device, and the like. A laser scanner or the like that writes an electrostatic latent image (mainly image data read by the document reading device 10 or image data taken from another recording medium) on the photosensitive drum 21 An exposure device 23, a developing device 24 that develops the electrostatic latent image written on the photosensitive drum 21 with each color component toner, a transfer roll that transfers the toner image on the photosensitive drum 21 onto the intermediate transfer belt 30, and the like. A drum cleaner 26 for removing residual toner on the primary transfer device 25 and the photosensitive drum 21 is provided.
Reference numeral 27 (27a to 27d) denotes a toner replenishing device that replenishes toner to the developing device 24, and each color toner is replenished to each developing device 24.

Further, the intermediate transfer belt 30 is made of a film-like endless belt having a volume resistivity of about 10 ⁹ to 10 ¹² Ω · cm, in which conductive carbon black is kneaded with polyimide resin, for example, and three tension rolls 32. ~ 34.
In this embodiment, the tension roll 33 is disposed below the tension roll 32 so that the intermediate transfer belt 30 is disposed obliquely downward, and each of the image forming units 20 (20a to 20d) is disposed. The intermediate transfer belt 30 is disposed below the intermediate transfer belt 30 along the intermediate transfer belt 30 between the tension roll 33 and the tension roll 34. Therefore, the scattering of toner in the image forming unit 20 does not affect the intermediate transfer belt 30, and a high-quality image with little contamination can be maintained.

  In this embodiment, the stretching roll 32 serves as a backup roll for the secondary transfer device 31, and the toner image formed on the intermediate transfer belt 30 by the image forming unit 20 is transferred to the secondary transfer device 31. In this way, it is designed to batch transfer onto paper. For this reason, since the toner image is formed on the intermediate transfer belt 30 and then secondarily transferred onto the paper, the toner image on the intermediate transfer belt 30 is prevented from being disturbed and the image quality is further improved. Formation is possible. Reference numeral 35 in the drawing is a belt cleaner that cleans residual toner on the intermediate transfer belt 30.

The fixing device 70 in the present embodiment is arranged in a substantially horizontal direction with respect to the secondary transfer position, and has a configuration as shown in FIG.
In the figure, a fixing device 70 recovers heat on the sheet S by a fixing unit 80 that melts and fixes the toner on the sheet S and a heat recovery unit HC on the downstream side of the fixing unit 80, and upstream of the fixing unit 80. Heat recovery transmission unit comprising a heat recovery belt 91 for transmitting heat recovered to the succeeding paper S in the side heat transfer section HT and seven stretching rolls 92 for stretching the heat recovery belt 91 The belt unit 90 is provided.

As shown in FIG. 4, the fixing unit 80 includes an upper unit 80a and a lower unit 80b. The upper unit 80a includes a pressure roll 81 and a heat insulating cover 82a provided so as to cover the pressure roll 81. The lower unit 80b includes a heating roll 86 in which a heater 87 is disposed, and the heating roll. And a heat insulating cover 82 b provided so as to cover 86. The heat insulating covers 82a and 82b have metal heat radiation plates 85a and 85b on the side of the pressure roll 81 and the heating roll 86, respectively, and the outer sides thereof are covered with the vacuum heat insulating materials 84a and 84b. Reference numerals 83a and 83b are exterior covers.
In the present embodiment, the pressure roll 81 and the heating roll 86 and the respective heat insulating covers 82a and 82b are arranged with a distance of, for example, 3 to 20 mm, and the heat insulating covers 82a and 82b are arranged with the pressure roll 81 and the heating roll. 86 is sandwiched from above and below. Further, in the present embodiment, the pressure roll 81 and the heating roll 86 are arranged to face each other in the vertical direction, so that the sheet S moves in a substantially horizontal direction in this nip area (see FIG. 3). However, the paper conveyance direction in the present application is not particularly limited to this.

On the other hand, in the belt unit 90 in the present embodiment, the heat recovery belt 91 is configured by laminating a silicone rubber layer 91b on a 75 μm-thick polyimide resin base material 91a as shown in FIG. The heat capacity is 450 J / (K · m ² ) or more. The heat recovery belt 91 contacts the sheet S at the heat recovery unit HC on the downstream side of the fixing unit 80 to recover the heat of the sheet S, circulates as it is, and then transfers the heat on the upstream side of the fixing unit 80. The part HT comes into contact with the paper S and transfers the recovered heat to the paper S.

As the heat recovery belt 91 in the present embodiment, it is necessary to appropriately select the heat capacity when performing heat recovery from the paper S and heat transfer to the paper S.
That is, if the heat capacity of the heat recovery belt 91 is too small, the temperature of the heat recovery belt 91 itself rises quickly, but even if heat is recovered from the paper S, it is recovered before heat transfer to the subsequent paper S is performed. The heat thus dissipated is easily dissipated, and when the heat transfer to the paper S before fixing is performed, the paper S may not be heated sufficiently, making it difficult to perform effective heat transfer.
On the contrary, if the heat capacity of the heat recovery belt 91 is too large, the rise of the temperature of the heat recovery belt 91 is delayed, and it takes time to stabilize. For this reason, it takes time to transfer heat effectively to the sheet S before fixing. For example, in a use form in which printing of several sheets is repeated, preheating the sheet S before fixing can be effectively performed. Absent.
Therefore, in order to effectively perform heat recovery / heat transfer with the heat recovery belt 91, it is preferable that the heat capacity is about the paper S to be used (per unit area) to about several times the heat capacity. Therefore, the heat recovery belt 91 is not limited to the configuration shown in FIG. 5 and is particularly limited as long as it has a heat resistance of about 100 to 120 ° C. and a heat capacity of 450 J / (K · m ² ) or more. Alternatively, for example, a heat resistant resin such as PEN (polyethylene naphthalate) and a belt having a thickness of 200 μm may be applied, or a silicone rubber single layer having a thickness of 200 μm may be applied.

Further, in the belt unit 90, the stretching roll 92 that stretches the heat recovery belt 91 is placed on a thin stainless steel (SUS) pipe 921 as shown in the plan view of FIG. 6 and the sectional view of FIG. The surface is covered with a foam layer 922 made of a foamed material such as urethane resin or silicone resin having an uneven shape, and the concave portion 922a and the convex portion 922b of the foam layer 922 are in a direction perpendicular to the axis of the tension roll 92. Is formed. In FIG. 6, reference numerals 92 a and 92 b are rotating shafts provided at both ends of the tension roll 92.
In the present embodiment, the surface of the tension roll 92 is covered with the foam layer 922, and the surface of the foam layer 922 is made uneven, so that heat recovery is performed in the contact area between the heat recovery belt 91 and the tension roll 92. The heat of the belt 91 is reduced from being absorbed by the tension roll 92 side. Further, by using the thin SUS pipe 921, the heat capacity of the stretching roll 92 itself can be reduced, and even if the temperature of the stretching roll 92 rises due to heat conduction or the like, it can be saturated quickly. The extra heat absorption by the tension roll 92 is reduced.
Therefore, heat recovery / heat transfer by the heat recovery belt 91 can be performed more efficiently.
In the present embodiment, the foam layer 922 has a stepped shape, but is not particularly limited as long as the heat recovery belt 91 can be circulated. Further, by reducing the thickness of the SUS pipe 921, the heat capacity of the tension roll 92 is reduced, the heat absorption from the heat recovery belt 91 to the tension roll 92 is further reduced, and the thermal efficiency of the heat recovery belt 91 is further improved. Will be able to.

Further, in the present embodiment, as shown in FIG. 3, for example, from a corotron or the like at a position separated from the heat recovery belt 91 so as to face the stretching roll 92 at the entrance of the heat transfer unit HT and the heat recovery unit HC. Corona chargers 93 and 94 are arranged as electrostatic attraction devices.
The two corona chargers 93 and 94 are supplied with a power source (not shown) so that the charging potential of the heat recovery belt 91 is positive on the heat transfer portion HT (polarity different from the charged charge of the toner) and negative on the heat recovery portion HC. Try to be on the side. That is, since the heat recovery belt 91 acts in the direction of attracting toner before the sheet S enters the fixing unit 80, the toner image can be prevented from being disturbed. 91 does not cause unnecessary charge up.
The tension roll 92 that faces the corona chargers 93 and 94 constitutes the counter electrode of the corona chargers 93 and 94. Therefore, the thickness of the foam layer 922 of the tension roll 92 is appropriately selected, and the heat The recovery belt 91 is sufficiently charged, and the sheet S is effectively attracted to the heat recovery belt 91.
Furthermore, in this embodiment, voltage application to the corona chargers 93 and 94 is performed only within the time during which the heat recovery belt 91 is driven. There is no charge up.

Furthermore, in the present embodiment, the drive mechanism of the heat recovery belt 91 is as shown in FIG. 8 in order to reduce the size of the fixing device 70.
In the figure, an intermediate gear 113 meshed with a drive gear 112 mounted on the rotation shaft of the drive motor 111 and a roll gear 116 mounted on a heating roll 86 of the fixing unit 80 are arranged to mesh with each other. Further, the gears mesh with each other so that the roll gear 115 of the stretching roll 92 rotates from the intermediate gear 113 via the gear 114.
Therefore, in the present embodiment, the heating roll 86 of the fixing unit 80 and the stretching roll 92 of the heat recovery belt 91 are both driven and rotated by the rotation of the drive motor 111. And the heat recovery belt 91 are rotated or moved in synchronization. In FIG. 8, the tension roll 92 to be driven is the inlet of the heat recovery unit HC, but the invention is not limited to this, and other tension rolls 92 may be used. Further, the heat insulating cover on the heating roll 86 side of the fixing unit 80 in the drawing is omitted.

  In the present embodiment, a heat shield hood 100 as shown in FIG. 9 is provided on the upper part of the belt unit 90 in order to prevent heat dissipation from the belt unit 90. The heat shield hood 100 is provided so as to cover the belt unit 90, and two support plates 101 (101 a, 101 b) that rotatably support both ends of the tension roll 92 of the belt unit 90, and the belt unit 90. It is comprised with the two top plates 102 and 103 which cover from above. All of these heat shielding hoods 100 are made of polycarbonate resin, and heat conduction, convection, and radiation from the heat recovery belt 91 and the like are suppressed, and the heat of the heat recovery belt 91 is sufficiently maintained.

  The reason why the support plate 101 can be formed of a non-metallic material such as polycarbonate resin in the present embodiment is that the belt unit 90 can be configured independently of the fixing unit 80, and the belt unit 90 side has a high pressure system like the fixing unit 80. It is because it does not need. That is, in order to support the tension roll 92 as the support plate 101, for example, the heat recovery belt 91 having a width of 300 mm only needs to support a belt tension of about 30 N (3 kgf).

  Further, in the present embodiment, as shown in FIG. 10, as a device for preventing the remaining shape of the heat recovery belt 91, one of the tension rolls 92 (specifically, on the most downstream side of the belt unit 90). A tension spring 98 is provided on the tension roll 92), and one end of the tension spring 98 is fixed to a stopper 99 that can be moved by a solenoid or the like. Then, while the heat recovery belt 91 is moving, the tension spring 98 is caused to act by the stopper 99. After the heat recovery belt 91 is stopped, the stopper 99 is moved in the direction B in FIG. Is not added to the tension roll 92.

Here, the remaining shape of the heat recovery belt 91 will be described.
FIG. 11 is a perspective view of the belt unit 90 and shows that a part (C portion) of the heat recovery belt 91 is raised outward.
Usually, the heat recovery belt 91 is operated at a high temperature, while the tension roll 92 is reduced in diameter in order to reduce the size of the fixing device 70. Therefore, when the heat recovery belt 91 is stopped, the high temperature heat recovery belt 91 is gradually cooled while being wound around the small-diameter tension roll 92, and the heat recovery belt 91 has a remaining shape of the tension roll 92. appear. At this time, the remaining shape is likely to occur particularly in a portion wound around the tension roll 92. When the heat recovery belt 91 in which the shape residue is generated reaches the heat transfer portion HT or the heat recovery portion HC as it is, the close contact with the paper is impaired and the heat efficiency is lowered.
Therefore, in the present embodiment, after the heat recovery belt 91 is stopped, the tension roll 92 is moved to loosen the tension on the heat recovery belt 91.

  In this embodiment, the tension spring 98 is controlled by the stopper 99. However, the method of reducing the tension of the heat recovery belt 91 is not limited to this, and for example, a tension roll using a solenoid or the like is used. 92 may be moved directly to reduce the tension.

  Further, in the present embodiment, as shown in FIG. 2, the paper feed trays 51 to 53 are separately provided above and below the image forming apparatus, and the high-frequency paper is provided in the paper feed tray 51 provided above. If this is applied, when the paper is replenished to the paper feed tray 51, the user can respond with a comfortable posture. Furthermore, in the present embodiment, since the paper discharge tray 55 is provided above the paper feed tray 51, the user can handle the paper with a comfortable posture when collecting the paper discharged to the paper discharge tray 55. It is like that. In the figure, reference numeral 54 denotes a manual feed tray that can be loaded with manual paper provided on the side of the image forming apparatus.

Furthermore, the paper transport path in the present embodiment is configured as follows. There are a first transport path 61 extending substantially vertically downward from the paper feed tray 51, a second transport path 62 extending upward from the paper feed trays 52 and 53, and a third transport path 63 extending from the manual feed tray 54. The conveyance path merges at the secondary transfer site, is connected to the main conveyance path 64, and extends to the paper discharge tray 55.
Further, a reversal conveyance path 65 is connected from the middle of the main conveyance path 64 to reverse the sheet and return it to the secondary transfer portion. In these conveyance paths, a large number of conveyance rolls are installed so that the conveyance of the sheet is performed reliably.

Next, a basic image forming process of the image forming apparatus according to the present embodiment will be described with reference to FIG. Now, when the image data of each color component image (yellow, magenta, cyan, black) read by the document reading device 10 is sent to the exposure device 23 of each image forming unit 20 (20a to 20d), each image formation is performed. An electrostatic latent image for each color component is formed on the photosensitive drum 21 of the unit 20, and the electrostatic latent image is visualized by the developing device 24 containing the corresponding color toner. An unfixed toner image of each color is formed on 21.
The unfixed toner images of the respective color components are sequentially primary transferred and superimposed on the intermediate transfer belt 30 by the primary transfer device 25 at the primary transfer portion where each photosensitive drum 21 and the intermediate transfer belt 30 are in contact with each other.

The unfixed toner image primarily transferred to the intermediate transfer belt 30 in this way is at the junction of the first conveyance path 61, the second conveyance path 62, and the third conveyance path 63 as the intermediate transfer belt 30 rotates. It is conveyed to a certain secondary transfer site.
At the secondary transfer portion, the intermediate transfer belt 30 is transferred onto a sheet conveyed from, for example, the sheet feeding tray 51 by a transfer bias (not shown) applied between the secondary transfer device 31 and the stretching roll 32. The unfixed toner image is transferred at once. The unfixed toner image that is collectively transferred onto the paper is fixed by the fixing device 70 and then discharged to the paper discharge tray 55 through the main conveyance path 64.

The operation of the fixing device 70 in such an image forming process will be described in detail with reference to FIG.
The sheet S on which the secondary transfer and the unfixed toner image have been transferred reaches the position of the heat recovery belt 91 charged by the corona charger 93 provided in the heat transfer portion HT, and is adsorbed to the heat recovery belt 91 side. The In this embodiment, since the unfixed toner image is transferred to the vertically lower side of the paper S, even if the paper S is attracted to the heat recovery belt 91 side, the toner image is not particularly deteriorated.

Then, before reaching the fixing unit 80, the sheet S is peeled off from the heat recovery belt 91 by using the waist of the sheet S or by using a peeling claw or the like, and is directed toward the fixing unit 80. The unfixed toner image on the paper S is fixed by passing through the nip region between the pressure roll 81 and the heating roll 86 in 80. The sheet S that has been fixed is adsorbed again to the heat recovery belt 91 charged by the corona charger 94 provided in the heat recovery section HC, and is conveyed as it is. Then, the sheet S is peeled off from the heat recovery belt 91 using the waist of the sheet S or using a peeling claw or the like, and is conveyed to the process after the fixing device 70.
At this time, since the heating roll 86 and the heat recovery belt 91 are rotated or moved in synchronization, the moving speed of the heat recovery belt 91 and the pressure roll 81 and the heating roll 86 of the fixing unit 80 Since the paper speed in the nip region is the same, there is no particular problem in the transportability of the paper S.

In such a fixing device 70, the sheet S discharged from the fixing unit 80 is heated by the heating roll 86 and has a high temperature (usually, it becomes equal to or higher than the melting point of the toner used for fixing). Although the same temperature is maintained immediately after being discharged from the fixing unit 80), the heat of the sheet S is heated by the heat recovery unit HC on the downstream side of the fixing unit 80 because the sheet S is in contact with the heat recovery belt 91. Heat conduction is performed to the recovery belt 91 side, and the temperature of the heat recovery belt 91 is increased. At this time, a belt having a heat capacity per unit area of 450 J / (K · m ² ) or more is used as the heat recovery belt 91, so that the heat capacity of the heat recovery belt 91 can be reduced to some extent, and the temperature increase rate ( (By heat recovery) can be made faster. At this time, since one side of the sheet S is exposed to the atmosphere, the heat of the sheet S is effectively transferred to the heat recovery belt 91 side having a low thermal resistance and is recovered.
Further, the heat recovery belt 91 that has finished recovering heat at the heat recovery unit HC contacts the sheet S that is next conveyed by the heat transfer unit HT on the upstream side of the fixing unit 80 through the circulation path as it is, and recovers heat. Heat collected in advance in the section HC is transferred to the paper S and preheated.

That is, in the present embodiment, the heat recovery belt 91 having a heat capacity per unit area shown in FIG. 5 having a heat capacity of 450 J / (K · m ² ) or more can be used to perform heat recovery and heat transfer to the paper S. A collection belt 91 is realized. Furthermore, by using a tension roll 92 having a foam layer 922 (see, for example, FIG. 6) as the tension roll 92 that supports the heat recovery belt 91, the tension roll 92 to which the heat recovery belt 91 contacts can be obtained. Heat absorption (heat is taken to the tension roll 92 side and the temperature of the heat recovery belt 91 is excessively reduced).
Therefore, in the present embodiment, the heat recovery belt 91 that has finished heat recovery in the heat recovery unit HC circulates as it is in the circulation path, and is subsequently conveyed by the heat transfer unit HT on the upstream side of the fixing unit 80. The heat recovered in advance by the heat recovery unit HC is transferred to the paper S, and effective preheating is performed.

  In addition, since the polarity applied to the corona chargers 93 and 94 and the application timing are taken into consideration, unnecessary charge-up on the heat recovery belt 91 can be suppressed, and stable adsorption performance of the paper S can be ensured over a long period of time. Effective preheating can be performed. Further, since the sheet S is adsorbed to the heat recovery belt 91 and conveyed, the posture of the sheet S when entering the fixing unit 80 can be stabilized, and the sheet in the fixing unit 80 due to skew or undulation of the sheet before fixing. It is also possible to prevent wrinkles.

Furthermore, in the present embodiment, the heat insulating hood 100 is also provided in consideration of the heat insulating property of the stretching roll 92 that stretches the heat recovery belt 91, so that heat can be recovered and transmitted more effectively. The heat insulating hood 100 is not limited to polycarbonate resin, but may be other resin materials as long as heat resistance and heat insulating properties are obtained.
Thus, in order to suppress the heat dissipation by the radiant heat from the surface of the heat recovery belt 91 or convection, the thermal efficiency is increased by providing the heat shield hood 100. Further, the heat shield hood 100 has an effect of taking in and maintaining the heat of the fixing unit 80 during standby to the belt unit 90 side, and also has an effect of easily obtaining a high heat recovery / transfer performance from the beginning of paper feeding. .

  Furthermore, in the present embodiment, after the heat recovery belt 91 is stopped, the belt tension is reduced, so that the occurrence of a residual shape in the heat recovery belt 91 can be prevented and the thermal efficiency during operation can be ensured. become.

As described above, in the present embodiment, since the sheet S before fixing can be effectively preheated, the thermal energy at the time of fixing can be reduced, and an image forming apparatus suitable for power saving and downsizing can be realized. It becomes like this.
In addition, since the driving mechanism of the fixing unit 80 and the belt unit 90 is only a gear arrangement, and the fixing unit 80 and the belt unit 90 are easily separated from each other, there is an advantage that processing such as a jam can be easily performed.
Further, in the method in which an unfixed toner image is formed on the lower surface of the sheet at the time of fixing as in the present embodiment, the advantage is that heat from the fixing unit 80 is effectively supplemented to the belt unit 90 side and heat is easily stored. There is also.

  In the present embodiment, the contact time between the heat recovery unit HC on the downstream side of the fixing unit 80 and the paper S at the heat transfer unit HT on the upstream side is substantially equal. The contact time between the heat recovery unit HC and the sheet S at the heat transfer unit HT may be changed depending on the temperature difference between the two and the device configuration.

FIG. 12 shows a tension roll 92 that differs only in shape from the tension roll 92 (see, for example, FIG. 6) used in the above-described embodiment, and the surface shape (uneven shape) of the foam layer 922 as a heat insulating layer. Is processed as shown in the figure.
This stretch roll 92 is provided with a convex portion 922b obliquely with respect to the roll axis. If the rotary shafts 92a and 92b are set so that the convex portion 922b rotates in the direction of arrow A in the figure, the tension roll 92 is stretched. When the gantry roll 92 rotates, a force can be applied in a direction in which the heat recovery belt 91 (see, for example, FIG. 3) is continuously stretched toward the outside of the belt (a direction orthogonal to the moving direction of the belt). The circulation posture of 91 can be further stabilized.
At this time, since the foam layer 922 similar to that of the above-described embodiment is formed, the heat absorption from the heat recovery belt 91 can be suppressed also in this example, and an image forming apparatus suitable for power saving is possible. become.

Embodiment 2
FIG. 13 shows a second embodiment of a fixing device 70 used in the image forming apparatus according to the present invention. Since the basic configuration of the image forming apparatus according to the present embodiment is the same as that of the first embodiment, it is omitted and only the fixing device 70 is shown. The fixing device 70 according to the present embodiment is configured in substantially the same manner as the fixing device according to the first embodiment, but instead of the corona charger as the electrostatic adsorption device used in the fixing device 70 according to the first embodiment. The charging member is different from the first embodiment. Components similar to those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and detailed description thereof is omitted here.

The fixing device 70 according to the present embodiment uses a tension roll 92 at the entrance of the heat transfer unit HT as a charging member. Therefore, a bias power source 95 with the tension roll 92 as a positive side is connected to the tension roll 92.
Further, immediately after the downstream of the fixing unit 80 at the entrance of the heat recovery unit HC, a plate charger 96 having a bias power source 97 connected to the outside of the heat recovery belt 91 is arranged so as to lightly contact the heat recovery belt 91. It is installed. A bias power source 97 is connected to the plate charger 96 so that the plate charger 96 side is a plus side. The plate charger 96 is made of a conductive member such as metal, and the surface thereof is provided with a highly releasable coating layer such as a fluororesin so as not to offset the toner of the sheet S after fixing. Has been.

In the present embodiment, the bias power supply 95 is connected to the stretching roll 92 at the entrance of the heat transfer section HT, so that the heat recovery belt 91 side is set to be positive, and the sheet S on which the negative toner is transferred is transferred to the heat recovery belt 91. Can be adsorbed to the side.
On the other hand, in the heat recovery unit HC, the heat recovery belt 91 is charged by the plate charger 96 so as to have a polarity different from that of the heat transfer unit HT. Then, the sheet S that has passed through the fixing unit 80 is directly adsorbed to the heat recovery belt 91 by the heat recovery unit HC. At this time, the charging of the heat recovery belt 91 is stabilized by grounding the stretching roll 92 at the entrance of the heat recovery unit HC.

Therefore, the heat recovery belt 91 and the sheet S can be closely contacted with each other in a state where both the heat transfer unit HT and the heat recovery unit HC are secured, and the same effects as those of the first embodiment can be obtained. Play. Also in the present embodiment, since the heat recovery belt 91 has different polarities in the heat transfer section HT and the heat recovery section HC, unnecessary charge-up is caused in a part of the heat recovery belt 91. It is preventing.
Further, in the present embodiment, since there are few components around the heat recovery belt 91 in particular, the size can be particularly reduced. Further, this has an advantage that it is easy to remove the paper when a jam such as a paper jam occurs.

Example 1
In this example, it is confirmed how the heat recovery efficiency from the paper changes depending on the heat capacity of the heat recovery belt with the same configuration as in the first embodiment. However, no thermal insulation hood is used.
Various conditions at this time were as follows.
As shown in FIG. 5, the heat recovery belt was formed by laminating a silicone rubber layer on a 75 μm polyimide resin base material, and changing the thickness of the silicone rubber layer to change the heat capacity per unit area. .
The stretch roll is a SUS pipe surface with an outer diameter of 13 mm and a wall thickness of 0.5 mm coated with a hard urethane foam with a thickness of 3 mm (thermal conductivity 0.01 to 0.05 W / (m · K)). It was used. In the present example, for the sake of simplicity, the surface of the stretched foam layer was not made uneven, but a flat foam layer was covered.
Under such conditions, the surface temperature of the heating roll of the fixing unit is maintained at 160 ° C., and A4 size, C2 paper (basis weight 70 gsm) manufactured by Fuji Xerox Co., Ltd. is fed as a sheet by lateral feed (LEF). Then, printing was performed 30 sheets per minute (paper feed speed at the fixing unit was 210 mm / s).

As shown in FIG. 14, the result shows that the heat recovery efficiency increases in proportion to the increase in the heat capacity until the heat capacity of the belt reaches 450 J / (K · m ² ), and if the heat capacity exceeds 450 J / (K · m ² ), the heat A tendency for the recovery efficiency to stabilize (become constant) at about 20% was confirmed. Moreover, it was confirmed that this tendency is the same up to 850 J / (K · m ² ).

  The contact time between the paper and the heat recovery belt was as follows. Usually, the heat exchange time between the paper and the heat recovery belt is determined by the heat capacity of the paper, and in the case of plain paper, the equilibrium is reached in 0.5 seconds or less. Therefore, in this embodiment, the contact time between the sheet before and after the fixing unit and the heat recovery belt is set to the same 0.5 seconds.

Example 2
This example evaluates the heat recovery efficiency (the reduction ratio when heat recovery is performed from the power consumption during continuous paper feeding when heat recovery is not performed) in the configuration of the first embodiment.
Various conditions were performed as follows.
The heat recovery belt was formed by laminating all silicone rubber on a polyimide resin layer of 75 μm to a total thickness of 250 μm (the heat capacity per unit area was 750 J / (K · m ² )).
The heating roll diameter of the fixing unit was 26.9 mm, and the surface speed was 160 mm / s.

Further, as a drive source, a heating roll and a tension roll (a tension roll disposed immediately after the fixing unit) are driven from the same drive motor using a gear train, and the surface speed of the heating roll and the heat recovery belt are The gear ratio was set so that the moving speed at the center of the thickness would be the same. The gear ratio in this example was 2.22.
At this time, the speeds of the two are not exactly the same, and the heat recovery belt side is set faster by 0.07%. However, within the range in which 420 mm in the A3 vertical direction passes, the image quality of the fixed image and the conveyance of the paper are set. It has been confirmed that there is no particular problem in the performance and heat recovery performance. It has been confirmed that by using the same drive source, it is not necessary to control the speed of the heating roll and the heat recovery belt, and the fixing device can be realized with a simple configuration and a stable sheet feeding speed.

Under such conditions, the surface temperature of the heating roll of the fixing unit is maintained at 160 ° C., and A4 size, C2 paper (basis weight 70 gsm) manufactured by Fuji Xerox Co., Ltd. is fed as a sheet by lateral feed (LEF). Then, printing of 30 sheets per minute (paper feeding speed at the fixing unit is 210 mm / s) was performed for 2 minutes.
As a result, when heat recovery was not performed, the power consumption during fixing was 13.26 Wh, but by performing heat recovery, it was reduced to 9.75 Wh, and the heat recovery efficiency was about 26%. .
In this embodiment, no heat insulating hood is used.

Example 3
In this example, the conditions for eliminating the influence of the remaining shape of the heat recovery belt in the configuration of the first embodiment were confirmed.
After performing continuous image formation using a belt unit tension roll with a 0.5 mm thick polyacetal resin (POM) layer formed on the surface of a SUS pipe having an outer diameter of 11 mm and a wall thickness of 0.5 mm After one night, the heat recovery belt was driven for a predetermined time before the paper reached the belt unit, and the paper was supplied to the belt unit after the influence of the remaining shape disappeared.
At this time, as a heat recovery belt, a single layer product of polyimide (75 μm) and a single layer product of silicone rubber (200 μm) were used for comparison.
As a result, in the single layer product of polyimide, the remaining shape is eliminated by rotating about 5 laps in the belt unit, and in the single layer product of silicone rubber, the remaining shape itself is small, and there is no effect with one rotation. It was.
Further, after these rotations, continuous image formation similar to that of Example 2 was performed, and it was confirmed that sufficient heat recovery and a good image were obtained with any belt material.

Example 4
In this embodiment, in order to prevent the remaining shape of the heat recovery belt, the effect of moving the heat recovery belt during standby when image formation is not performed has been confirmed.
In this example, in the configuration of the first embodiment, in order to reduce the load on the heat recovery belt and the load on the drive source, the drive was performed at a speed of 30 mm / s for 1 minute every 30 minutes.
It was confirmed that the remaining shape on the heat recovery belt can be suppressed by performing such control.
Needless to say, the driving interval, driving time, and driving speed may be appropriately selected depending on the belt material.

Example 5
This example was performed in order to confirm the effect of the tension spring in the configuration of the first embodiment.
First, the relationship between the belt tension and the remaining shape was examined. At a tension of about 4.9 N (0.5 kgf) or less, the driving of the belt itself becomes unstable. Little occurred.
From this, it was confirmed that, for example, a belt having a width of about 300 mm has an effect of sufficiently preventing the remaining shape by making the tension about 4.9 N (0.5 kgf) or less.

Example 6
In this example, the same evaluation as in Example 1 was performed. At this time, a heat insulating hood was provided on the upper part of the fixing device, and an effect of the heat insulating hood was confirmed.
In this example, the heat recovery belt was a belt having a heat capacity per unit area of 600 J / (K · m ² ) (total thickness 200 μm), and the heat shield hood was made of polycarbonate resin.
Under such conditions, the surface temperature of the heating roll of the fixing unit is maintained at 160 ° C., and A4 size, C2 paper (basis weight 70 gsm) manufactured by Fuji Xerox Co., Ltd. is fed as a sheet by lateral feed (LEF). Then, printing was performed 30 sheets per minute (paper feed speed at the fixing unit was 210 mm / s).
For comparison, when compared with the state without the heat shield hood, the heat recovery efficiency without the heat shield hood is about 21%, and with the heat shield hood, the heat recovery efficiency is about 25% (both (2 minute value) was obtained, and an efficiency increase of about 4 points was confirmed as an effect of the heat shield hood.

FIG. 2 is an explanatory diagram showing an outline of a fixing device according to the present invention. 1 is an explanatory diagram showing an overview of an image forming apparatus according to Embodiment 1. FIG. FIG. 2 is an explanatory diagram illustrating a fixing device according to a first embodiment. FIG. 2 is an explanatory diagram illustrating a fixing unit in the fixing device according to the first embodiment. FIG. 3 is an explanatory diagram illustrating a heat recovery belt of the fixing device according to the first embodiment. FIG. 3 is an explanatory diagram illustrating an overview of a tension roll of the fixing device according to the first embodiment. FIG. 3 is an explanatory diagram showing a cross section of the tension roll according to the first embodiment. FIG. 3 is an explanatory diagram illustrating a driving mechanism of the fixing device according to the first embodiment. FIG. 3 is an explanatory diagram showing a heat shield hood according to the first embodiment. 3 is an explanatory diagram illustrating a tension applying method according to Embodiment 1. FIG. It is explanatory drawing which shows the shape remainder of a heat recovery belt. It is explanatory drawing which shows the modification of the tension roll of Embodiment 1. FIG. FIG. 6 is an explanatory diagram illustrating an outline of a fixing device according to a second embodiment. It is explanatory drawing which shows the heat recovery efficiency of Example 1. FIG. It is explanatory drawing which shows the fixing device using the conventional heat pipe. It is explanatory drawing which shows the fixing device using the conventional heat transfer belt.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fixing unit, 2 ... Heat recovery transmission unit, 3 ... Belt member, 4 ... Stretch member, 4a ... Thermal insulation layer, 5 ... Recording material, 6 ... Drive source, HC ... Heat recovery part, HT ... Heat transfer part

Claims (21)

In a fixing device comprising: a fixing unit that heats a toner image on a recording material; and a heat recovery transmission unit that recovers heat of the recording material sent from the fixing unit and transmits it to the recording material sent to the fixing unit.
The heat recovery transmission unit has a belt member that is stretched around a plurality of stretching members and circulates around the fixing unit,
Of this belt member, on the downstream side of the fixing unit, there is provided a heat recovery unit that performs heat recovery in a state of contacting the recording material and insulating the periphery of the area facing the contact portion, and on the upstream side of the fixing unit. Is provided with a heat transfer portion that is in contact with the recording material and heat transfer is performed in a state where the area surrounding the contact portion is insulated.
A fixing device characterized in that a driving source of a belt member is also used as a driving source of a member related to conveyance of another recording material. The fixing device according to claim 1.
A fixing device characterized in that the driving source of the belt member also serves as the driving source of the fixing unit. The fixing device according to claim 2.
The belt device and the fixing unit are connected to each other by a gear from a driving source and are driven, and the belt member and the fixing unit are independently supported and removable except for the gear. The fixing device according to claim 1.
The fixing device, wherein the belt member is set to be driven for a predetermined time before the recording material reaches the heat transfer section. The fixing device according to claim 1.
A fixing device, wherein the belt member is driven at a predetermined speed for a predetermined time during a period in which the fixing device is on standby. The fixing device according to claim 1.
A fixing device that reduces belt tension after the belt member stops. The fixing device according to claim 1.
A fixing device, wherein the heat transfer unit and the heat recovery unit are provided with an electrostatic adsorption device for adsorbing the recording material to the belt member by electrostatic force. The fixing device according to claim 7.
The fixing device, wherein the two electrostatic adsorption devices disposed in the heat transfer unit and the heat recovery unit are configured such that the charging polarities of the belt members are opposite to each other. The fixing device according to claim 8.
An electrostatic adsorption device provided in a heat transfer unit is disposed in a non-contact manner with a toner image surface of a recording material. The fixing device according to claim 8.
The fixing device, wherein the electrostatic adsorption device provided in the heat transfer unit is a corona charger. The fixing device according to claim 10.
The electrostatic adsorption device provided in the heat transfer unit applies a bias having a polarity different from the charged polarity of the toner to the tension member of the belt member. The fixing device according to claim 8.
The fixing device, wherein the electrostatic adsorption device provided in the heat recovery unit is a corona charger disposed in a non-contact manner with respect to the recording material. The fixing device according to claim 8.
The fixing device, wherein the electrostatic adsorption device provided in the heat recovery unit is a plate-like or film-like charging member disposed in contact with the toner image surface of the recording material. The fixing device according to claim 13.
A fixing device, wherein a surface of the charging member is provided with a release layer. The fixing device according to claim 8.
The fixing device characterized in that the electrostatic attraction device is driven at least while the belt member is driven. The fixing device according to claim 1.
A fixing device having a heat capacity per unit area of a belt member of 450 J / (K · m ² ) or more. The fixing device according to claim 1.
The fixing device, wherein the belt member is an endless belt made of a heat-resistant resin material or a heat-resistant rubber material. The fixing device according to claim 1.
The fixing device, wherein the belt member is an endless belt in which a heat-resistant resin material and a heat-resistant rubber material are laminated. The fixing device according to claim 1.
A fixing device, wherein a tension member that stretches a belt member is supported by a support member that is formed of a low thermal conductivity member. The fixing device according to claim 1.
A fixing device characterized in that a cover for preventing heat dissipation of the belt member is provided in a moving path of the belt member from the heat recovery unit to the heat transfer unit. An image forming engine for forming a toner image on a recording material;
An image forming apparatus comprising: a fixing device according to claim 1 for fixing a toner image formed on the recording material.

Images