JP2011232376A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively heat a great quantity of gas for peeling of recording paper without providing an exclusive heater or a power source for heating the gas and further more while suppressing more than necessary lowering of temperature in a fixing heat source.SOLUTION: The fixing device includes a heat roller which is heated by a prescribed heating member; a press roller pressing the heat roller; and a gas discharge means arranged on an ejection side of a nip section formed by the heat roller and the press roller for discharging the gas from a nozzle to a recording medium which passed the nip section and having the recording medium peeled off from the heat roller. In this case, the gas discharge means is composed, in at least one portion of a flow path for having the gas flow to the nozzle, regarding a surface adjacent to the heat roller (heat roller adjacent surface) and a different surface (heat roller non adjacent surface) from the heat roller adjacent surface in the same position in the flowing direction of the flow path, so that heat transmission on the heat roller adjacent surface is greater than the heat transmission in the heat roller non adjacent surface.

Description

  The present invention relates to a fixing device that heats and pressurizes unfixed toner on a recording medium such as recording paper and an image forming apparatus including the fixing device. The present invention relates to an improvement in technology for discharging a gas and peeling a recording medium from a fixing roller.

  2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions, a latent image corresponding to an original is formed on a photosensitive member, and toner is applied to the latent image. Thus, the visualized toner image is transferred onto the recording paper, and then the toner image transferred onto the recording paper is fixed and discharged.

  As a fixing device for fixing a toner image in this manner, a recording sheet on which a toner image is transferred is sandwiched between a nip portion formed by a heating roller incorporating a halogen heater and the like and a pressure roller that presses the heating roller. There is a fixing device of a heat roller fixing system that heats and pressurizes while conveying, and such a fixing device is widely used because of its simple configuration.

  Further, an endless fixing belt is stretched between a heating roller incorporating a halogen heater or the like and a fixing roller, and a pressure roller that presses the fixing roller through the fixing belt is provided. There is a belt-fixing type fixing device that heats and pressurizes while pinching and transporting the recording paper onto which the toner image is transferred at the formed nip part. Such a fixing device has a small heat capacity of the fixing belt, so it warms up. It has the advantage of reducing time and contributing to energy saving.

  In recent years, fixing devices that perform induction heating locally using an IH heater instead of a halogen heater have begun to be used.

  Here, since the toner of the toner image on the recording paper is heated when it passes through the nip portion, the toner acts like an adhesive, and the recording paper that has passed through the nip portion does not peel off, but the heating roller or fixing belt. There is a risk that it will adhere to the surface of the wrapping material and wrap around, causing jamming.

  In particular, when a thin paper with a small amount of paper or a coated paper for printing with a small amount of paper is used as the recording paper, the peeling performance tends to be further deteriorated.

  For this purpose, a fixing device is known in which a peeling claw is provided in the vicinity of the heating roller, and the sharp tip of the peeling claw is pressed against the surface of the heating roller. Therefore, even when the recording paper is wound around the heating roller and discharged, the peeling claw comes into contact with the leading end portion of the recording paper and the recording paper is peeled off from the heating roller, so that the above problem is solved.

  However, since the sharp tip of the peeling claw is in pressure contact with the surface of the heating roller, the release layer formed from a fluororesin or the like covering the surface of the heating roller is worn due to relatively short use, The tip of the peeling claw may be worn away, and if it is left as it is, defective fixing will occur.

  In order to solve such a problem, fixing is performed by ejecting compressed gas to the heating roller on the recording paper discharge side with respect to the nip portion, and peeling the leading end portion of the recording paper wound around the heating roller by the wind pressure of the compressed gas. An apparatus is known (see, for example, Patent Documents 1 and 2).

JP 2005-157179 A JP 2007-187715 A

  In the fixing device disclosed in Patent Document 1, a nozzle that discharges a compressed gas to the recording paper discharge side with respect to the nip portion to peel off the leading end portion of the recording paper wound around the heating roller, and the peeled recording paper do not contact the nozzle. A guide plate for guiding is provided. Further, when a low-temperature compressed gas hits a high-temperature recording paper that has just been fixed, uneven gloss may occur. Therefore, a heater is provided in the nozzle and the compressed gas is discharged in a heated state.

  However, only by providing the heater in the nozzle, only the compressed gas stored near the nozzle before discharge is heated, and the compressed gas stored in the back away from the heater is not heated. This Patent Document 1 describes that the compressed gas flows for a short time (for example, 0.01 to 0.1 sec) only once or intermittently at some time interval. In the case of feeding only one sheet, the heated compressed gas can be used, but if the recording paper cannot be peeled unless it is ejected intermittently, When a large number of recording sheets are continuously fed, the low-temperature compressed gas stored in the back is also discharged, and it is difficult to reliably prevent uneven gloss. Therefore, a large-capacity heater is required to continuously heat the compressed gas flowing during discharge.

  In addition, in order to reliably peel the recording paper, it is necessary to provide at least about three nozzles in the width direction of the recording paper. When a large-capacity heater is provided for each of the plurality of nozzles, Therefore, there is a problem in that the apparatus becomes large and the cost increases.

  On the other hand, in Patent Document 2, instead of providing a large-capacity heater, a part of the flow path for sending the compressed gas to the nozzle is devised to heat the compressed gas using heat generated by the heating roller. Yes. In this case, a large-capacity heater is not necessary, and it appears as if it is efficient at first glance.

  However, by making this gas flow path approach the heating roller, heat from the heating roller can be efficiently received in the gas flow path, but heat from the heating roller is released to the outside through this gas flow path. In some cases, such a problem may occur. For this reason, the heat of the heating roller is taken more than necessary, and the temperature may be lowered.

  The present invention has been made in view of such a problem. When a gas flow is used for peeling a recording sheet in the vicinity of a fixing roller, a dedicated heater or a power source for gas heating is not provided, and the fixing heat source is more than necessary. It is an object of the present invention to propose a fixing device and an image forming apparatus that can efficiently heat a large volume of gas while suppressing a decrease in temperature.

  The object is achieved by the invention described below.

  The fixing device of the present invention is disposed on the discharge side of a nip portion formed by a heating roller heated by a predetermined heating member, a pressure roller for pressing the heating roller, and the heating roller and the pressure roller. And a gas discharge means for discharging gas from the nozzle to the recording medium that has passed through the nip portion and peeling the recording medium from the heating roller, wherein the gas discharge means causes the gas to flow to the nozzle. In at least a part of the path, a surface close to the heating roller (heating roller proximity surface) and a surface that is the same position in the flow direction of the path and is different from the heating roller proximity surface (heating roller non-proximity surface) The heat transfer property of the heating roller adjacent surface is configured to be higher than the heat transfer property of the heating roller non-adjacent surface.

  Further, the fixing device of the present invention includes a heating roller heated by a predetermined heating member, a fixing roller, an endless fixing belt stretched around the heating roller and the fixing roller and driven to circulate, A pressure roller that presses the fixing roller through a fixing belt; and a discharge side of a nip portion formed by the fixing belt and the pressure roller; Gas discharge means for discharging gas from a nozzle and peeling the recording medium from the fixing belt, and the gas discharge means is disposed on the heating member in at least a part of a path for flowing the gas to the nozzle. The heating roller is a surface that is close (heating roller proximity surface) and a surface that is the same position in the flow direction of the same path and that is different from the heating roller proximity surface (heating roller non-proximity surface). Heat conductivity of the contact surface is configured to be higher than heat conductivity of the heating roller non adjacent surface, characterized in that.

  In addition, an image forming apparatus of the present invention includes the above fixing device.

  According to the fixing device and the image forming apparatus of the present invention, in the fixing device that discharges the gas from the nozzle to the leading end portion of the recording paper that has passed through the nip portion and peels the recording medium from the heating roller or the fixing belt, the gas is supplied to the nozzle. A part of the flow path to be flown is arranged at a position where the heat of the heating member that heats the heating roller is transmitted by heat conduction or heat radiation, and the heat transfer property of the heating roller adjacent surface is the heat transfer property of the non-heating roller adjacent surface. Because it is configured to be higher than the heat source, it will not take away heat from the heat source more than necessary, and it will not dissipate, without providing a dedicated heater or power source for gas heating, and more than necessary for the fixing heat source It is possible to efficiently heat a large volume of gas for peeling the recording paper while suppressing the temperature drop. As a result, uneven gloss after fixing can be surely prevented, and an increase in size and cost of the apparatus can be avoided.

FIG. 2 is a configuration diagram illustrating a cross-sectional configuration of a fixing device according to an exemplary embodiment. 1 is a perspective view illustrating a configuration of a fixing device according to an exemplary embodiment. FIG. 2 is a configuration diagram illustrating a cross-sectional configuration of a fixing device according to an exemplary embodiment. FIG. 2 is a configuration diagram illustrating a configuration of a main part of a fixing device according to an exemplary embodiment. FIG. 2 is a configuration diagram illustrating a configuration of a main part of a fixing device according to an exemplary embodiment. FIG. 2 is a configuration diagram illustrating a configuration of a main part of a fixing device according to an exemplary embodiment. FIG. 2 is a configuration diagram illustrating a configuration of a main part of a fixing device according to an exemplary embodiment. FIG. 2 is a configuration diagram illustrating a configuration of a main part of a fixing device according to an exemplary embodiment. FIG. 2 is a configuration diagram illustrating a configuration of a main part of a fixing device according to an exemplary embodiment. 1 is a configuration diagram illustrating a configuration of an image forming apparatus having a fixing device.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings.

  First, an image forming apparatus having the fixing device of the present embodiment will be described with reference to the basic configuration diagram of FIG.

  In FIG. 10, a photosensitive drum 1 is an electrophotographic photosensitive member as an image carrier, and the photosensitive drum 1 is rotationally driven in a direction indicated by an arrow at a predetermined peripheral speed, and its surface is negatively charged by a charger 2. It is uniformly charged to a predetermined potential VH.

  The exposure device 3 is a device that exposes the photosensitive drum 1, and outputs a laser beam modulated in accordance with a time-series digital pixel signal of image information input from an image reading device (not shown), a computer, or the like. The uniformly charged surface of the photosensitive drum 1 is scanned and exposed by this laser beam. As a result, the absolute value of the potential of the exposed portion of the photosensitive drum 1 decreases to become the potential VL, and an electrostatic latent image is formed on the surface of the photosensitive drum 1.

  The developing unit 4 is a developing unit that visualizes the electrostatic latent image on the photosensitive drum 1, and includes a developing roller 4a that is driven to rotate. The developing roller 4a is disposed opposite to the photosensitive drum 1, and a thin layer of negatively charged toner is formed on the outer peripheral surface thereof. A developing bias voltage whose absolute value is smaller than the potential VH of the photosensitive drum 1 and larger than the potential VL is applied to the developing roller 4a, whereby the toner on the developing roller 4a becomes the potential of the photosensitive drum 1. Reversal development is performed only on the VL portion, and a toner image is formed.

  On the other hand, a recording medium (hereinafter referred to as recording paper P) as a transfer material fed from a paper supply unit (not shown) passes through a registration roller 61 and is synchronized with the rotation of the photosensitive drum 1 at an appropriate timing. And the transfer area formed by the charged transfer pole 5. The toner image on the photosensitive drum 1 is transferred to the recording paper P by the charged transfer pole 5 to which a transfer bias is applied.

  The fixing guide 62 is a conveying means for fixing, and the recording paper P onto which the toner image has been transferred is conveyed toward the fixing device 7 on the fixing guide 62 and the toner image transferred onto the recording paper P is transferred. Fixing is done. The recording paper P that has passed through the fixing device 7 and has been fixed with the toner image is discharged onto a paper discharge tray (not shown).

  On the other hand, the photosensitive drum 1 from which the recording paper P has been peeled is removed by the cleaning device 9 to remove transfer residue toner and the like adhering to the surface thereof, and the cleaned photosensitive drum 1 is repeatedly subjected to the next image formation. To be served.

  Although the above-described image forming apparatus is an apparatus that forms a monochrome image, the present invention is also applied to an apparatus that forms a color image.

  Next, the fixing device 7 of the present embodiment will be described in detail with reference to FIG. 1 and subsequent drawings. 1 is a configuration diagram showing a cross-sectional configuration of the fixing device of the present embodiment, and FIG. 2 is a perspective view showing a configuration of the fixing device of the present embodiment.

  In FIG. 1, the fixing device 7 includes a heating roller 71 that is heated by a heating member such as a halogen heater H, a pressure roller 72 that pressurizes the heating roller 71 from below, and the like.

  The heating roller 71 is formed of a halogen heater H built in the center, a cored bar 71a formed in a cylindrical shape with aluminum, iron, or the like, and a fluorine resin such as PFA (perfluoroalkoxy) or PTFE (polytetrafluoroethylene). And a release layer 71b that coats or coats the cored bar 71a with a tube.

  The pressure roller 72 is formed of a core metal 72a formed of a stainless steel or the like, an elastic layer 72b made of a foam of silicon rubber and positioned on the outer peripheral surface of the core metal 72a, a PFA tube, and the like. And a release layer 72c covering the outer peripheral surface of 72b. The pressure roller 72 is urged by a urging member (not shown) to press the heating roller 71 from below.

  As a heating member for heating the heating roller 71, an induction heating (IH) method may be used instead of the halogen heater H.

  With the above configuration, when the heating roller 71 heated by the halogen heater H and driven by a motor (not shown) rotates in the clockwise direction, the pressure roller 72 rotates in the counterclockwise direction. Accordingly, the recording paper P on which the toner image is formed by the image forming apparatus as shown in FIG. 10 is sandwiched and conveyed by the nip portion N formed by the heating roller 71 and the pressure roller 72, and is heated and pressurized. As a result, the toner image on the recording paper P is fixed.

  Here, the toner image on the recording paper P is pressed against the surface of the heating roller 71, and the recording paper P is prevented from being wrapped around the heating roller 71 due to the adhesiveness of the softened toner. A gas discharge means 700 is provided for discharging the gas and peeling the leading end of the recording paper P wound around the heating roller 71 by the wind pressure of the gas. A nozzle 720 for discharging the gas is provided on the discharge side of the recording paper P with respect to the nip N. Is provided.

  The gas supply unit 800 generates a predetermined pressure or a predetermined amount of gas flow (gas flow) at a predetermined timing in accordance with the fixing timing of the recording paper P, and the gas from the gas supply unit 800 flows in a cylindrical flow path. It is discharged from the nozzle 720 via 710.

  In the present embodiment, the gas flow (gas flow) is a flow generated by discharging a compressed gas that has been compressed by a compressor such as a pump or a compressor or previously compressed and stored in a cylinder or the like. And the case of the flow of uncompressed gas generated by a blowing means such as a fan is included.

  That is, the gas supply unit 800 includes a compressor that generates a compressed gas, a cylinder in which the compressed gas is stored, a blowing unit such as a fan that causes a flow to flow in an uncompressed gas such as air, a valve or a blowing unit of a compressor or a cylinder. It is comprised by the drive part etc. which drive.

  The gas may be air existing around the gas supply unit 800 or the fixing device 7, or may be a gas other than air when a cylinder is used.

  Furthermore, the gas supply unit 800 may reuse the air used for heat dissipation in each part of the image forming apparatus, such as a CPU or a power supply circuit. In this case, the gas supply unit 800 may have a fan common to the device that radiates heat of each unit.

  Note that a plurality of flow paths 710 and nozzles 720 may be provided in accordance with the axial direction of the heating roller 71 (in the direction perpendicular to the paper surface of FIG. 1), but as shown in FIG. It is desirable that the cross section be a rectangular cylinder with the axial direction as the longitudinal direction.

  When the recording paper P passes through the nip portion N, gas is discharged from the nozzle 720, and the leading end of the recording paper P wound around the heating roller 71 is peeled off from the heating roller 71. Note that the time for ejecting the gas from the nozzle 720 may be a short time for peeling off the leading end of the recording paper, and it may be either continuously ejected or intermittently ejected in pulses.

  Here, in the gas discharge means 700, between the gas supply part 800 and the nozzle 720, the flow path 710 as a path | route through which gas flows is comprised. A surface adjacent to the heating roller 71 or an IH heating source (not shown) in at least a part of the flow path 710 is a heating roller proximity surface 711. Also in the nozzle 720, if structurally possible, at least a part of the nozzle close to the heating roller 71 or an IH heating source (not shown) may be used as the heating roller proximity surface 721. In addition, a surface different from the heating roller proximity surface 711 in at least a part of the flow path 710 is a heating roller non-adjacent surface 712. In addition, in the nozzle 720, if structurally possible, a surface different from the surface (heating roller proximity surface 721) of at least a part of the nozzle adjacent to the heating roller 71 or an IH heating source (not illustrated) is provided on the heating roller. The non-proximity surface 722 may be used. Here, the heating roller non-proximity surface 712 includes a heating roller non-proximity surface 712 facing the heating roller proximity surface 711, side surfaces 700a and 700b (see FIG. 2) of the heating roller proximity surface 711, and a heating roller proximity surface 711. A surface 712 ′ that is the same surface but is not close to the heating roller 71 corresponds to this.

  In this embodiment, the gas discharge means 700 is configured such that the heat transfer property of the heating roller proximity surface 711 is higher than the heat transfer property of the heating roller non-adjacent surface 712. As a result, the gas discharge means 700 does not take away the heat of the heating source more than necessary and dissipates it, and without further providing a dedicated heater or power source for heating the gas, the temperature of the heating source is further lowered than necessary. This makes it possible to efficiently heat a large volume of gas for peeling the recording paper. As a result, uneven gloss after fixing can be surely prevented, and an increase in size and cost of the apparatus can be avoided.

  FIG. 3 is a configuration diagram showing a cross-sectional configuration when the fixing device of the present embodiment is applied to a belt fixing type fixing device. In addition, the same code | symbol is attached | subjected to the same thing as FIG.

  The fixing belt 74 is formed in an endless manner. For example, a heat-resistant resin belt made of PI (polyimide) or the like is used as a base, the outer peripheral surface of the base is covered with heat-resistant silicon rubber, and further, as a release layer. It is covered with a PFA (perfluoroalkoxy) tube.

  The heating roller 71 incorporates a halogen heater H as a heating member for heating the fixing belt 74. For example, the outer peripheral surface of a cylindrical hollow rotating body formed of aluminum or the like is covered with a heat-resistant PFA tube, It is configured as a hard roller.

  The fixing roller 73 is configured as a soft roller by covering a solid core 73a made of metal such as iron with a heat-resistant silicone rubber 73b and further covering with a sponge 73c.

  The pressure roller 72 includes a cored bar formed of stainless steel or the like, an elastic layer made of silicon rubber foam and positioned on the outer peripheral surface of the cored bar, and an outer peripheral surface of the elastic layer formed of a PFA tube or the like. And a release layer for coating. The pressure roller 72 is urged by a urging member (not shown) to press the heating roller 71 from below.

  Note that any heating member may be used as a heating member for heating the fixing belt 74, for example, an induction heating heating element using an exciting coil may be used. Further, the heating member is not necessarily arranged in the heating roller 71 or the like, and may be arranged anywhere.

  In the above configuration, when the fixing roller 73 is rotated clockwise by a driving unit (not shown), the fixing belt 74 and the heating roller 71 are rotated clockwise, and the pressure roller 72 is rotated counterclockwise. Further, since the heating roller 71 can be heated by the halogen heater H, the fixing belt 74 in contact with the heating roller 71 is also heated.

  Since the pressure roller 72 is urged in the direction of the fixing roller 73 by an urging means (not shown), the nip portion N between the fixing belt 74 wound around the fixing roller 73 and the pressure roller 72. Thus, the fed recording paper P is heated and pressurized, and the toner image on the recording paper P is fixed.

  Here, the toner image on the recording paper P is pressed against the surface of the heating roller 71 and the recording paper P is prevented from being wound around the fixing belt 74 due to the adhesiveness of the softened toner. A gas discharge means 700 is provided for discharging gas and peeling the leading end portion of the recording paper P wound around the fixing belt 74 by the wind pressure of the gas flow, and the nozzle 720 for discharging the gas is the discharge side of the recording paper P with respect to the nip portion N. Is provided.

  The gas supply unit 800 generates a predetermined pressure or a predetermined amount of gas flow (gas flow) at a predetermined timing in accordance with the fixing timing of the recording paper P, and the gas from the gas supply unit 800 flows in a cylindrical flow path. It is discharged from the nozzle 720 via 710.

  Note that a plurality of flow paths 710 and nozzles 720 may be provided in accordance with the axial direction of the heating roller 71 (the direction perpendicular to the paper surface of FIG. 3). However, as shown in FIG. It is desirable that the cross section be a rectangular cylinder with the axial direction as the longitudinal direction.

  When the recording paper P passes through the nip portion N, gas is discharged from the nozzle 720, and the leading end portion of the recording paper P wound around the fixing belt 74 is peeled off from the fixing belt 74. Note that the time for discharging the gas from the nozzle 720 may be short, and it may be either continuously discharged or intermittently discharged in pulses.

  Here, the fixing device of FIG. 3 also includes the same gas discharge means 700 as in FIG. 1 so that the heat transfer property of the heating roller proximity surface 711 is higher than the heat transfer property of the heating roller non-contact surface 712. Therefore, the heat source is not deprived of heat more than necessary, and the heat source is no longer dissipated. It is possible to efficiently heat a large volume of gas for peeling the recording paper while suppressing it. As a result, uneven gloss after fixing can be surely prevented, and an increase in size and cost of the apparatus can be avoided.

  Hereinafter, referring to FIG. 4 and the subsequent drawings, a large capacity gas for removing the recording paper can be efficiently removed without providing a dedicated heater or power source for gas heating, and further suppressing a temperature drop more than necessary for the fixing heat source. A fixing device that can be heated will be described.

  FIG. 4 is a configuration diagram showing a cross-sectional configuration of the flow path 710 disposed in the vicinity of the heating roller 71 and the nozzle 720 in the gas discharge means 700. Here, the difference in heat conductivity described above can be considered as a difference between the thermal conductivity of the heating roller proximity surface 711 and the thermal conductivity of the heating roller non-proximity surface 712. In this case, in the gas discharge means 700, the heat conductivity of the heating roller proximity surface 711 is configured to be higher than the heat conductivity of the heating roller non-proximity surface 712. It is desirable that the heat conductivity of the heating roller proximity surface 721 is also configured to be higher than that of the heating roller non-proximity surface 722.

  In this case, since the heat conductivity of the heating roller proximity surfaces 711 and 721 is higher than that of the heating roller non-proximity surfaces 712 and 722, heat is easily absorbed from the heating roller 71, and a large capacity for peeling the recording paper. The gas can be heated efficiently.

  Furthermore, since the heat conductivity of the heating roller non-proximity surfaces 712 and 722 is lower than that of the heating roller proximity surfaces 711 and 721, it is difficult to dissipate the heat of the heated gas from the heating roller non-proximity surfaces 712 and 722 to the outside. Therefore, it becomes possible to waste heat of the heating roller 71 and to suppress a temperature drop of the heating roller 71.

  FIG. 5 is a configuration diagram showing a cross-sectional configuration of the flow path 710 disposed in the vicinity of the heating roller 71 and the nozzle 720 in the gas discharge means 700. Here, the difference in heat conductivity described above can be considered as a difference between the heat capacity of the heating roller proximity surface 711 and the heat capacity of the heating roller non-proximity surface 712. Here, the heat roller non-proximity surfaces 712 and 722 are provided with outer surfaces 712b and 722b having a large heat capacity so as to cover the outer sides of the flow path inner surfaces 712a and 722a. In the configuration shown in FIG. 4 described above, the heat capacity of the heating roller non-proximity surface 712 may be larger than the heat capacity of the heating roller proximity surface 711. In addition to the configuration shown in FIG. 4 described above, outer surfaces 712b and 722b having a large heat capacity as shown in FIG. 5 may be mounted.

  In this case, in the gas discharge means 700, the heat capacity of the heating roller adjacent surface 711 is configured to be smaller than the heat capacity of the heating roller non-adjacent surface 712. It is desirable that the heat capacity of the heating roller proximity surface 721 is also configured to be smaller than the heat capacity of the heating roller non-proximity surface 722.

  In this case, since the heat capacity of the heating roller proximity surfaces 711 and 721 is smaller than that of the heating roller non-proximity surfaces 712 and 722, a change in heat from the heating roller 71 is easily transmitted in a short time, and for recording paper peeling. A large volume of gas can be heated efficiently.

  Furthermore, since the heat capacity of the heating roller non-proximity surfaces 712 and 722 is larger than that of the heating roller proximity surfaces 711 and 721, it is difficult to dissipate the heat of the heated gas from the heating roller non-proximity surfaces 712 and 722 to the outside. The heat of the heating roller 71 can be wasted and the temperature drop of the heating roller 71 can be suppressed.

  FIG. 6 is a configuration diagram showing a cross-sectional configuration of the flow path 710 disposed in the vicinity of the heating roller 71 and the nozzle 720 in the gas discharge means 700. Here, the difference in heat conductivity described above can be considered as a difference between the heat capacity of the heating roller proximity surface 711 and the heat capacity of the heating roller non-proximity surface 712.

  Here, although the heating roller proximity surface 711 and the heating roller non-proximity surface 712 are made of the same material, the thickness of the heating roller non-proximity surface 712 is greater than the thickness of the heating roller proximity surface 711. As a result, in the gas discharge means 700, the heat capacity of the heating roller proximity surface 711 is configured to be smaller than the heat capacity of the heating roller non-proximity surface 712. It is desirable that the heat capacity of the heating roller proximity surface 721 is also configured to be smaller than the heat capacity of the heating roller non-proximity surface 722.

  In this case, since the heat capacity of the heating roller proximity surfaces 711 and 721 is smaller than that of the heating roller non-proximity surfaces 712 and 722, a change in heat from the heating roller 71 is easily transmitted in a short time, and for recording paper peeling. A large volume of gas can be heated efficiently.

  Furthermore, since the heat capacity of the heating roller non-proximity surfaces 712 and 722 is larger than that of the heating roller proximity surfaces 711 and 721, it is difficult to dissipate the heat of the heated gas from the heating roller non-proximity surfaces 712 and 722 to the outside. The heat of the heating roller 71 can be wasted and the temperature drop of the heating roller 71 can be suppressed.

  It should be noted that good results can be obtained by further applying the configuration of FIG. 6 to the configuration of FIG. 4 or the configuration of FIG. 5 and further to the configuration having both FIG. 4 and FIG.

  FIG. 7 is a configuration diagram showing a cross-sectional configuration of the flow path 710 disposed in the vicinity of the heating roller 71 and the nozzle 720 in the gas discharge means 700. Here, the difference in heat conductivity described above can be considered as a difference between the surface state of the heating roller proximity surface 711 and the surface state of the heating roller non-proximity surface 712.

  In this case, in the gas ejection means 700, the surface state of the heating roller proximity surface 711 is configured to have more irregularities 711a than the surface state of the heating roller non-adjacent surface 712. On the other hand, the surface state of the heating roller non-proximity surface 712 is smoother with less unevenness than the surface state of the heating roller proximity surface 711. Although not shown, it is desirable that the surface states of the heating roller proximity surface 721 and the heating roller non-proximity surface 722 are similarly configured.

  In this case, in the gas discharge means 700, the surface state of the heating roller proximity surface 711 has more irregularities on the surface than the heating roller non-proximity surfaces 712 and 722, and heat is easily absorbed from the heating roller 71. A large volume of gas for peeling can be efficiently heated. In addition, as this surface state with many unevenness | corrugations, the thing like a fin generally used as a heat radiator is made to act as a heat absorber in this embodiment.

  Furthermore, since the surface state of the heating roller non-proximity surfaces 712 and 722 is smoother than that of the heating roller proximity surface 711, it is difficult to dissipate the heat of the heated gas from the heating roller non-proximity surfaces 712 and 722 to the outside. Therefore, it is possible to waste heat of the heating roller 71 and to suppress a temperature drop of the heating roller 71.

  It should be noted that good results can also be obtained by further applying the configuration of FIG. 7 to the configuration of FIG. 4, the configuration of FIG. 5, the configuration of FIG. 6, or the combination of the configurations of FIGS.

  FIG. 8 is a configuration diagram showing a cross-sectional configuration of the flow path 710 disposed in the vicinity of the heating roller 71 and the nozzle 720 in the gas discharge means 700. Here, the difference in heat conductivity described above can be considered as a difference between the surface state of the heating roller proximity surface 711 and the surface state of the heating roller non-proximity surface 712.

  In this case, the heating roller proximity surface 711 is provided with an uneven member 711B so as to cover the outside of the flow path inner side surface 711A, and has more unevenness than the surface state of the heating roller non-adjacent surface 712.

  On the other hand, the surface state of the heating roller non-proximity surface 712 is smoother with less unevenness than the surface state of the heating roller proximity surface 711. Although not shown, it is desirable that the surface states of the heating roller proximity surface 721 and the heating roller non-proximity surface 722 are similarly configured.

  In this case, in the gas discharge means 700, the surface state of the heating roller proximity surface 711 has more irregularities on the surface than the heating roller non-proximity surfaces 712 and 722, and heat is easily absorbed from the heating roller 71. A large volume of gas for peeling can be efficiently heated. In addition, as this surface state with many unevenness | corrugations, the uneven | corrugated member 711B like a fin generally used as a heat radiator is made to act as a heat absorber in this embodiment.

  Furthermore, since the surface state of the heating roller non-proximity surfaces 712 and 722 is smoother than that of the heating roller proximity surface 711, it is difficult to dissipate the heat of the heated gas from the heating roller non-proximity surfaces 712 and 722 to the outside. Therefore, it is possible to waste heat of the heating roller 71 and to suppress a temperature drop of the heating roller 71.

  It should be noted that good results can be obtained by further applying the configuration of FIG. 8 to the configuration of FIG. 4, the configuration of FIG. 5, the configuration of FIG. 6, or the combination of the configurations of FIGS.

  FIG. 9 is a configuration diagram showing a cross-sectional configuration of the flow path 710 disposed in the vicinity of the heating roller 71 and the nozzle 720 in the gas discharge means 700. Here, as the difference in heat conductivity described above, it can be considered as a difference between substances added to the heating roller proximity surface 711 and the heating roller non-adjacent surface 712.

  In this case, on the heating roller proximity surface 711, another substance 711b having a higher thermal conductivity than the inner surface 711A of the flow path is added outside the inner surface 711A of the flow path without covering the entire surface. On the other hand, on the heating roller non-proximity surface 712, another substance 712b having a lower thermal conductivity than the flow path inner side surface 712A is added outside the flow path inner side surface 712A without covering the entire surface. Here, the different substance means a substance having a thermal conductivity different from that of the substance constituting the flow path 710.

  As a result, in the gas discharge means 700, the heat conductivity of the heating roller proximity surface 711 is configured to be higher than the heat conductivity of the heating roller non-proximity surface 712. In addition, it is desirable that the heat conductivity of the heating roller proximity surface 721 is higher than that of the heating roller non-proximity surface 722 by adding another similar material.

  In this case, since the heat conductivity of the heating roller proximity surfaces 711 and 721 is higher than that of the heating roller non-proximity surfaces 712 and 722, heat is easily absorbed from the heating roller 71, and a large capacity for peeling the recording paper. The gas can be heated efficiently. Furthermore, since the heat conductivity of the heating roller non-proximity surfaces 712 and 722 is lower than that of the heating roller proximity surfaces 711 and 721, it is difficult to dissipate the heat of the heated gas from the heating roller non-proximity surfaces 712 and 722 to the outside. Therefore, it becomes possible to waste heat of the heating roller 71 and to suppress a temperature drop of the heating roller 71.

  In this case, in the heating roller proximity surface 711, another substance 711b having a smaller heat capacity than the flow path inner side surface 711A may be added outside the flow path inner side surface 711A without covering the entire surface. On the other hand, in the heating roller non-proximity surface 712, another substance 712b having a larger heat capacity than the flow path inner side surface 712A may be added outside the flow path inner side surface 712A without covering the entire surface. Here, the different substance means a substance having a heat capacity different from that of the substance constituting the flow path 710.

  As a result, in the gas discharge means 700, the heat capacity of the heating roller proximity surface 711 is configured to be smaller than the heat capacity of the heating roller non-proximity surface 712. In addition, it is desirable that the heat capacity of the heating roller proximity surface 721 is configured to be smaller and higher than the heat capacity of the heating roller non-proximity surface 722 by adding another similar material.

  In this case, since the heat capacity of the heating roller proximity surfaces 711 and 721 is smaller than that of the heating roller non-proximity surfaces 712 and 722, a change in heat from the heating roller 71 is easily transmitted in a short time, and for recording paper peeling. A large volume of gas can be heated efficiently. Furthermore, since the heat capacity of the heating roller non-proximity surfaces 712 and 722 is larger than that of the heating roller proximity surfaces 711 and 721, it is difficult to dissipate the heat of the heated gas from the heating roller non-proximity surfaces 712 and 722 to the outside. The heat of the heating roller 71 can be wasted and the temperature drop of the heating roller 71 can be suppressed.

  In the configuration of FIG. 9, it is possible to add different substances on both the heating roller proximity surface 711 and the heating roller non-adjacent surface 712, or to add another material only on the heating roller proximity surface 711 side, Another substance may be added only on the proximity surface 712 side.

  Alternatively, a recess may be provided in advance on the additional material addition surface of the heating roller proximity surface 711 and the heating roller non-adjacent surface 712, and the additional material may be added to the recess so as not to protrude from the surface. Good. In particular, on the heating roller non-proximity surface 712 side, it is desirable to make the surface smooth and uniform in order to suppress heat dissipation.

  It should be noted that good results can also be obtained by further applying the configuration of FIG. 9 to the configuration of FIG. 4, the configuration of FIG. 5, the configuration of FIG. 6, or the configuration of FIGS. Further, in the configuration of FIG. 8, good results can also be obtained by applying the configuration of FIG. 9 to the heating roller non-proximity surface 712 side.

7 Fixing Device 71 Heating Roller 72 Pressing Roller 73 Fixing Roller 74 Fixing Belt 710 Flowing Path 711 Heating Roller Proximity Surface 712 in Flowing Path Heating Roller Non-Proximity Surface 720 Nozzle 721 Heating Roller Proximity Surface 722 in Nozzle Heating Roller in Nozzle Non-proximity surface 800 Gas supply part H Halogen heater N Nip part P Recording paper

Claims (7)

A heating roller heated by a predetermined heating member;
A pressure roller for pressing the heating roller;
Disposed on the discharge side of the nip part formed by the heating roller and the pressure roller, gas is discharged from the nozzle to the recording medium passing through the nip part, and the recording medium is peeled off from the heating roller. Means,
With
The gas discharge means is
In at least a part of the path for flowing the gas to the nozzle, the heating is performed by a surface close to the heating roller (heating roller proximity surface) and a surface different from the heating roller proximity surface (heating roller non-proximity surface). The heat transfer property of the roller proximity surface is configured to be higher than the heat transfer property of the heating roller non-contact surface,
A fixing device. A heating roller heated by a predetermined heating member;
A fixing roller;
An endless fixing belt that is stretched around the heating roller and the fixing roller and is circulated and driven;
A pressure roller for pressing the fixing roller via the fixing belt;
Disposed on the discharge side of the nip portion formed by the fixing belt and the pressure roller, gas is discharged from the nozzle to the tip of the recording medium that has passed through the nip portion, and the recording medium is peeled off from the fixing belt. Gas discharge means for causing;
With
The gas discharge means is
In at least a part of the path for allowing the gas to flow to the nozzle, the heating is performed by a surface close to the heating member (heating roller proximity surface) and a surface different from the heating roller proximity surface (heating roller non-proximity surface). The heat transfer property of the roller proximity surface is configured to be higher than the heat transfer property of the heating roller non-contact surface,
A fixing device. The heat transfer is thermal conductivity,
The heat conductivity of the heating roller adjacent surface is configured to be higher than the heat conductivity of the heating roller non-adjacent surface,
The fixing device according to claim 1, wherein the fixing device is a magnetic head. The heat transfer is heat capacity,
The heat capacity of the heating roller adjacent surface is configured to be smaller than the heat capacity of the heating roller non-adjacent surface,
The fixing device according to claim 1, wherein the fixing device is a magnetic head. The heat transfer is realized by the surface shape,
The heating roller proximity surface has a shape with higher heat transfer than the heating roller non-proximity surface.
The fixing device according to claim 1, wherein The heat transfer is realized by another substance added to the members constituting the flow path,
The different material is added to at least one of the heating roller proximity surface or the heating roller non-proximity surface so that the heat roller proximity surface is higher in heat transfer than the heating roller non-proximity surface.
The fixing device according to claim 1, wherein   An image forming apparatus comprising the fixing device according to claim 1.

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