JP2007057643A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely fit a heat insulating member to a fixing roller in a rotation stopping state in accordance with the thickness reduction of the fixing roller even when the fixing roller is made thin in thickness. <P>SOLUTION: In the fixing device 20, a paper P is supplied to a nip part N formed by the axially rotatable fixing roller 30 wherein a heating element 24 as a heating source is incorporated and a pressure roller 70 which is rotatable around a roller shaft 71 extending in the same direction as that of the shaft of the fixing roller 30 in a state that the circumferential surface of the roller 70 is brought in press contact with the circumferential surface of the fixing roller 30, then, a toner image on the paper P is thermally fixed. A first locking projection 44 which is protrusively formed from the inner circumferential surface toward a radius direction is arranged on the annular heat insulating member 40 which is concentrically fitted on the fixing roller 30, and also, a locking hole 31 into which the first locking projection 44 is fitted is formed in the fixing roller 30. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device that is applied to an image forming apparatus such as a copying machine or a facsimile machine and that performs a fixing process on a recording medium on a toner image transferred to a recording medium such as paper.

  Conventionally, a fixing device applied to an image forming apparatus as described in Patent Document 1 is known. The fixing device is for fixing the toner image on the paper on which the toner image formed on the peripheral surface of the photosensitive drum is transferred to the paper, a fixing roller having a heater built therein, A pressure roller that is pressed against the fixing roller. By supplying the paper toward the nip between the synchronously rotating fixing roller and the pressure roller, the fixing roller heats the paper. The toner image is subjected to a fixing process.

  An annular heat insulating member is externally fitted to both ends of the fixing roller in such a fixing device, and a bearing is externally fitted to each heat insulating member, and these bearings are respectively supported by mutually opposing side walls of a predetermined housing. Thus, the fixing roller is supported by the housing so as to be rotatable around the axis.

Such a fixing roller is provided with cut portions (referred to as a fixing roller side key surface) formed on the outer peripheral surface of both ends in parallel with the shaft center, while the fixing roller is provided on the inner peripheral surface of the heat insulating member. A flat surface portion (referred to as a heat insulating member side key surface) corresponding to the side key surface is provided, and the heat insulating member is fitted into the end of the fixing roller with the heat insulating member side key surface corresponding to the fixing roller side key surface. The heat insulating member is externally fitted to the fixing roller in a non-rotating state.
Japanese Patent Laid-Open No. 10-3223

  However, in the anti-rotation structure formed between the fixing roller and the heat insulating member composed of the fixing roller side key surface and the heat insulating member side key surface as described above, the end portion of the fixing roller is cut. Thus, the key surface of the fixing roller must be formed, and for this purpose, the fixing roller must have a thickness dimension enough to withstand cutting.

  By the way, in recent years, the thickness of the fixing roller can be adjusted to increase the heating speed of the fixing roller so that the image forming process can be performed in as short a time as possible after the image forming apparatus is turned on. Thinning as much as possible is done. If the thickness dimension of the fixing roller is reduced, the mechanical strength is reduced, so that it becomes difficult to form a fixing roller side key surface at the end by cutting, and this limits the thinning of the fixing roller. Inconvenience arises.

  The present invention has been made in view of such a situation. Even when the fixing roller is thinned, the fixing member can be attached to the fixing roller in a non-rotating state corresponding to the thinning. The object is to provide a device.

  According to the first aspect of the present invention, the fixing is performed by heating the toner image on the recording medium by supplying the recording medium to the peripheral surface of the fixing roller which is provided with a heating source and is rotatable about the axis. The fixing roller is provided with an annular heat insulating member that is concentrically fitted on the fixing roller, and the annular heat insulating member has a first locking protrusion protruding in a radial direction from an inner peripheral surface. On the other hand, the fixing roller is provided with a locking hole into which the first locking protrusion is inserted.

  According to this configuration, by supplying the recording medium to the peripheral surface of the fixing roller that rotates about the axis, the recording medium obtains heat from the fixing roller having a heat source therein and applies the heat to the toner image. The image is conveyed while being subjected to the fixing process, and is discharged from the fixing roller to complete the fixing process.

  In such a fixing device, the fixing roller has an annular heat insulating member that is concentrically fitted, and the annular heat insulating member is provided with a first locking protrusion that protrudes in the radial direction from the inner peripheral surface. On the other hand, since the fixing roller is provided with a locking hole into which the first locking projection is fitted, for example, the fixing roller is elastically deformed (specifically, for example, the diameter is increased) while being elastically deformed. And the first heat-insulating protrusion of the annular heat insulating member is fitted into the fixing hole of the fixing roller, whereby the annular heat insulating member is attached to the fixing roller in a non-rotating state.

  Therefore, even if the fixing roller has a small thickness dimension, and the conventional anti-rotation key surface cannot be cut on the fixing roller, the first locking projection is provided on the annular heat insulating member side, By providing a locking hole corresponding to the first locking projection on the fixing roller side, the annular heat insulating member can be securely attached to the fixing roller in a non-rotating state.

  According to a second aspect of the present invention, in the first aspect of the present invention, an annular gear is externally fitted to the annular heat insulating member so as to drive and rotate the fixing roller about its axis. A second locking projection is provided projecting in a radial direction from the surface, while the annular heat insulating member is fitted in the second locking projection, extends in the axial direction, and has one end A locking groove which is an open end is provided.

  According to such a configuration, the second locking projection protruding from the inner peripheral surface of the annular gear is fitted from the open end into the locking groove extending in the axial direction provided in the annular heat insulating member. Thus, the annular gear is attached to the annular heat insulating member in a non-rotating state. Then, the annular gear is attached to the fixing roller by fitting the second locking projection into the locking groove with respect to the annular heat insulating member that has been previously attached to the fixing roller. And are integrated so as to be able to rotate together with the fixing roller.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the annular heat insulating member is configured to be divided into a plurality of divided bodies in the circumferential direction.

  According to such a configuration, since the annular heat insulating member is mounted on the fixing roller by assembling the divided members so as to surround the fixing roller, the mounting operation of the annular heat insulating member on the fixing roller is facilitated.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, each of the divided bodies is formed with a fitting structure that fits each other on the opposing surfaces.

  According to such a configuration, in a state where the divided bodies are assembled to form the annular heat insulating member, the combined state of the divided bodies is stabilized by the fitting structure provided on the contact surfaces of each other.

  According to a fifth aspect of the present invention, in the invention according to the third or fourth aspect, each of the divided bodies is dimensioned so that a gap is formed on the opposing surface in a state of being mounted on the fixing roller. It is a feature.

  According to such a configuration, each of the divided bodies is dimensioned so that a gap is formed on the opposite surface when mounted on the fixing roller, so that the divided bodies are adjacent to each other in a state of being assembled around the fixing roller. Spatial margins (ie, gaps) are created between the divided bodies, which causes problems in the mounting state due to dimensional errors during manufacturing (specifically, the inner surfaces of the divided bodies are fixed by contact of the opposing surfaces of the divided bodies) Inconveniences such as failure to adhere to the peripheral surface of the roller are prevented.

  According to a sixth aspect of the present invention, in the invention according to any one of the third to fifth aspects, each of the divided bodies has a curvature inner diameter dimension set smaller than an outer diameter dimension of the fixing roller. To do.

  According to such a configuration, each of the divided bodies has a large radius of curvature by pressing the annular gear into the annular heat insulating member in a state in which each divided body is mounted around the fixing roller to form the annular heat insulating member. Therefore, the elastic force closely contacts the peripheral surface of the fixing roller, thereby stabilizing the mounting state of each divided body (that is, the annular heat insulating member) on the fixing roller.

  The invention according to claim 7 is the invention according to any one of claims 3 to 6, wherein each of the divided bodies is subjected to chamfering treatment on a radially outer edge portion of each opposing surface. Is.

  According to such a configuration, in a state in which each divided body is assembled around the fixing roller, even if a step is formed between the outer surfaces of the adjacent divided bodies due to a manufacturing error, the divided bodies are mutually connected. Since the chamfering process is performed on the radially outer edge portion of the opposing surface of each of the adjacent surfaces, a steep step between the outer surfaces of the adjacent divided bodies is relieved, which makes it easy to fit the annular gear to the annular heat insulating member made of each divided body. .

  The invention according to an eighth aspect is the invention according to any one of the third to seventh aspects, wherein each of the divided bodies is formed flat on an outer surface side at a contact position. .

  According to such a configuration, even if there is a step due to a manufacturing error or the like on the outer surface side of the contact position of each divided body that is a component of the annular heat insulating member, this portion is formed flat, When other members such as bearings are externally fitted to the annular heat insulating member, there is no inconvenience that it is difficult to fit due to the presence of the step, and the other members are smoothly externally fitted to the annular heat insulating member.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein one end portion of the annular heat insulating member is an annular tapered portion inclined outward from the outer peripheral surface toward the axial center. Is formed.

  According to this configuration, when the annular gear is fitted into the annular heat insulating member attached to the fixing roller, the annular gear is guided to the annular tapered portion formed at one end of the annular heat insulating member. The workability of the mounting work with respect to the annular heat insulating member is improved.

  According to the first aspect of the present invention, the annular heat insulating member that is concentrically fitted to the fixing roller is provided with the first locking protrusion that protrudes in the radial direction from the inner peripheral surface. Since the roller is provided with a locking hole into which the first locking protrusion is inserted, the first locking protrusion of the annular heat insulating member is fixed after being externally fitted to the fixing roller while elastically deforming the annular heat insulating member. By fitting in the locking hole of the roller, the annular heat insulating member can be mounted on the fixing roller in a non-rotating state.

  Therefore, even if the fixing roller has a small thickness dimension, and the conventional anti-rotation key surface cannot be cut on the fixing roller, the first locking projection is provided on the annular heat insulating member side, By providing a locking hole corresponding to the first locking projection on the fixing roller side, the annular heat insulating member can be securely attached to the fixing roller in a non-rotating state, thereby making the thickness dimension of the fixing roller as thin as possible. Therefore, improvement in heat transfer efficiency can contribute to quick start-up after the image forming apparatus is turned on.

  According to the second aspect of the present invention, the second locking projection protruding from the inner peripheral surface of the annular gear is inserted into the locking groove provided in the annular heat insulating member and extending in the axial direction from the open end thereof. By fitting, the annular gear is attached to the annular heat insulating member in a non-rotating state, and therefore the second locking protrusion is fitted into the locking groove with respect to the annular heat insulating member that has been previously attached to the fixing roller. As a result, the annular gear can be integrated with the fixing roller via the annular heat insulating member, whereby the driving force of a predetermined driving means can be transmitted to the fixing roller via the annular gear.

  According to the invention of claim 3, since the annular heat insulating member is configured to be divided into a plurality of divided bodies in the circumferential direction, the annular heat insulating member is fixed to the fixing roller by assembling the divided bodies around the fixing roller. Therefore, the workability of the work of assembling the annular heat insulating member to the fixing roller can be improved.

  According to invention of Claim 4, since each division body is formed with the fitting structure which mutually fits in a mutually opposing surface, in the state which assembled | attached each division body and formed the annular heat insulation member The coupling state of each divided body can be stabilized by the fitting structure provided on the mutual contact surfaces.

  According to the fifth aspect of the present invention, each of the divided bodies is dimensioned so that a gap is formed on the opposing surface in a state of being mounted on the fixing roller, so that each divided body is assembled around the fixing roller. Spatial margins can be made between adjacent divided bodies in the state, which makes it possible to prevent problems in the mounting state due to dimensional errors during manufacturing and the like, and the annular heat insulating member can be securely mounted to the fixing roller. it can.

  According to the sixth aspect of the present invention, each of the divided bodies has a radius of curvature inner diameter dimension set smaller than the outer diameter dimension of the fixing roller. In this state, by pressing the annular gear into the annular heat insulating member, each divided body is elastically deformed so that the radius of curvature becomes large, and this elastic force closely contacts the peripheral surface of the fixing roller. Thus, it is possible to stabilize the mounting state of each divided body with respect to the fixing roller.

  According to the seventh aspect of the present invention, since each divided body is chamfered at the radially outer edges of the opposing surfaces, even if each divided body is assembled around the fixing roller, a manufacturing error may occur. Even if a step may be formed between the outer surfaces of the adjacent divided bodies, the steep step between the outer surfaces of the adjacent divided bodies is relaxed, so that the annular gear is made of the annular heat insulation composed of each divided body. It can be easily fitted into the member, and the workability of the assembly work can be improved.

  According to the eighth aspect of the present invention, even if there is a step on the outer surface side of the contact position of each divided body that is a constituent element of the annular heat insulating member due to a manufacturing error or the like, this portion is formed flat. Therefore, when other members such as gears and bearings are externally fitted to the annular heat insulating member, there is no inconvenience that it is difficult to fit due to the presence of the step, and other members can be smoothly externally fitted to the annular heat insulating member. it can.

  According to the ninth aspect of the present invention, the annular gear is attached to the fixing roller because the one end portion of the annular heat insulating member is formed with the annular tapered portion that is inclined outward from the outer peripheral surface toward the axial center. When fitted into the annular heat insulating member, the annular gear is guided by an annular tapered portion formed at one end of the annular heat insulating member, thereby improving the workability of the mounting operation of the annular gear to the annular heat insulating member. Can do.

  FIG. 1 is an explanatory front sectional view showing an outline of an internal structure of an embodiment of a printer 10 which is a kind of an image forming apparatus to which a fixing device according to the present invention is applied. As shown in FIG. 1, the printer 10 includes a sheet storage unit 12 that stores a sheet (recording medium) P to be used for printing processing, and a sheet bundle P1 that is fed out from the sheet bundle P1 stored in the sheet storage unit 12. The apparatus main body 11 includes an image forming unit 13 that performs image transfer processing on the paper P and a fixing unit 14 that performs fixing processing on the paper P on which transfer processing has been performed by the image forming unit 13. At the same time, a paper discharge unit 15 for discharging the paper P subjected to fixing processing by the fixing unit 14 is provided at the top of the apparatus main body 11. The paper discharge unit 15 is formed by recessing the top of the apparatus main body 11, and a paper discharge tray 151 for receiving the discharged paper P is provided at the bottom of the concave recess.

  A predetermined number (one in this embodiment) of paper cassettes 121 is provided in the paper storage unit 12 so as to be detachable from the apparatus main body 11. At the downstream end (left side in FIG. 1) of the paper cassette 121, a pickup roller 122 that feeds the paper P one by one from the paper bundle P1 is provided. The paper P fed out of the paper cassette 121 by driving the pickup roller 122 is supplied to the image forming unit 13 through the paper feed conveyance path 123 and the registration roller pair 124 provided at the downstream end of the paper feed conveyance path 123. It is supposed to be paper.

  The image forming unit 13 performs a transfer process on the paper P based on image information transmitted from a computer or the like, and is provided so as to be rotatable around an axis extending in the front-rear direction (a direction perpendicular to the paper surface of FIG. 1). The charger 132, the exposure device 133, the developing device 134, the transfer roller 135, and the cleaning device 136 are clockwise from the upper right position in FIG. 1 of the photosensitive drum 131 along the peripheral surface of the photosensitive drum 131. Is formed.

  The photosensitive drum 131, the charger 132, and the cleaning device 136 are housed in a predetermined housing and unitized as a photosensitive unit 130.

  The photosensitive drum 131 is for forming an electrostatic latent image and a toner image along the electrostatic latent image on the peripheral surface, and an amorphous silicon layer is laminated on the peripheral surface, whereby these images are displayed. It is suitable for forming.

  The charger 132 forms a uniform charge on the peripheral surface of the photosensitive drum 131 rotating clockwise around the axis, and imparts a charge to the peripheral surface of the photosensitive drum 131 by corona discharge. It is supposed to be. Note that a charging roller may be employed instead of the charger 132.

  The exposure device 133 irradiates the peripheral surface of the rotating photosensitive drum 131 with a laser beam to which intensity is applied based on image data transmitted from an external device such as a computer, and thereby the photosensitive drum 131 is irradiated with the laser beam. An electrostatic latent image is formed on the peripheral surface of the photosensitive drum 131 by erasing the electric charge in the portion where the laser light on the peripheral surface is checked.

  The developing device 134 supplies toner to the peripheral surface of the photosensitive drum 131 to attach the toner to a portion where the electrostatic latent image is formed on the peripheral surface, and thereby the toner image is formed on the peripheral surface of the photosensitive drum 131. Is formed.

  The transfer roller 135 transfers a positively charged toner image formed on the peripheral surface of the photosensitive drum 131 to the paper P with respect to the paper P sent to the position immediately to the left of the photosensitive drum 131. Thus, a negative charge having a polarity opposite to that of the toner image is applied to the paper P.

  Accordingly, the sheet P that has reached the lower left position of the photosensitive drum 131 is pressed and sandwiched between the transfer roller 135 and the photosensitive drum 131 while the toner image on the circumferential surface of the photosensitive drum 131 that is positively charged is negatively charged. The sheet P is peeled off toward the surface of P, whereby the transfer process is performed on the sheet P.

  The cleaning device 136 scatters when the toner remaining on the peripheral surface of the photosensitive drum 131 after the transfer process and the foreign material such as dust attached to the charging wire by the charger 132 are scattered and the photosensitive member. This is for removing and adhering things adhering to the peripheral surface of the drum 131. The cleaning device 136 is provided with a rubbing roller 136 a that rubs against the peripheral surface of the photosensitive drum 131, and residual toner and foreign matter adhering to the peripheral surface of the photosensitive drum 131 are rubbed by the rotation of the rubbing roller 136 a. (Ie, the peripheral surface of the photosensitive drum 131 is polished). The peripheral surface of the photosensitive drum 131 cleaned by the cleaning device 136 goes to the charger 132 again for the next image forming process.

  The fixing unit 14 performs a fixing process by heating the toner image of the paper P that has been subjected to the transfer process by the image forming unit 13, and includes a fixing device 20. The fixing device 20 includes a fixing roller 30 that applies heat to the paper P, and a pressure roller 70 that is disposed opposite to the left side of the fixing roller 30.

  Then, the sheet P after the transfer process is sent toward a nip portion N formed between the fixing roller 30 and the pressure roller 70 and passes through the nip portion N, so that the heat from the fixing roller 30 is transferred. And the fixing process is performed. The paper P subjected to the fixing process is discharged to the paper discharge unit 15 through the paper discharge conveyance path 141.

  A blower 16 having a filter 161 for taking in outside air at the upper right position in FIG. 1 in the apparatus main body 11 and the outside air taken in by the blower 16 through the filter 161 are directed toward the photosensitive unit 130. A blowing duct 17 for guiding is provided. The outside air blown toward the photoconductor unit 130 through the air duct 17 by driving the blower 16 penetrates the photoconductor unit 130, and thereby the photoconductor is not provided by a heater (not shown) provided in the photoconductor drum 131. When the inside of the unit 130 is overheated, the inside of the photoreceptor unit 130 is cooled.

  FIG. 2 is a perspective view showing the embodiment of the fixing device as seen from the back side. Therefore, in FIG. 2, the positional relationship between the left and right sides of the fixing device 20 shown in FIG. 1 is reversed (that is, in FIG. 1, the fixing roller 30 is located on the right side and the pressure roller 70 is located on the left side. In FIG. 2, the fixing roller 30 is located on the left side and the pressure roller 70 is located on the right side).

  As shown in FIG. 2, the fixing device 20 is configured by arranging a fixing roller 30 and a pressure roller 70 side by side in a housing 21. The casing 21 includes a rear plate 211 on the near side in FIG. 2, a front plate 212 on the opposite side, and a pair of side plate members 213 provided between the side edges of the rear plate 211 and the front plate 212. A mounting space V for mounting the fixing roller 30 and the pressure roller 70 is formed in a space surrounded by the back plate 211, the front plate 212, and the side plate member 213.

  In the mounting space V, the fixing roller 30 is mounted at the left position in FIG. 2 between the back plate 211 and the front plate 212, and the peripheral surface is contacted with the peripheral surface of the fixing roller 30 at the right position. The pressure roller 70 is attached in a state of contact.

  A bearing 60 is mounted on each end of the fixing roller 30 via an annular heat insulating member 40 to be described later. The bearing 60 of the fixing roller 30 is recessed in the back plate 211 and the front plate 212, respectively. By being fitted into the recess, it is mounted in the mounting space V of the housing 21 so as to be rotatable around the axis. The pressure roller 70 is pivotally supported by a roller shaft 71 provided between the back plate 211 and the front plate 212 at the right position of the fixing roller 30 in FIG. 2 in the mounting space V, and is driven by the rotation of the fixing roller 30. Thus, it rotates around the roller shaft 71.

  An annular gear 50, which will be described later, is fitted on the end of the fixing roller 30 on the front side of the bearing 60 in FIG. 2 so as to be integrally rotatable, while the back plate 211 is driven by a drive motor (not shown). A drive gear 22 that rotates around the gear shaft 221 is provided. The drive gear 22 is meshed with the annular gear 50, whereby the rotation of the drive gear 22 driven by the drive motor is transmitted to the fixing roller 30 via the annular gear 50.

  Further, the back plate 211 is provided with a terminal block 23 so as to face the end opening of the fixing roller 30, and extends from the terminal block 23 toward the inner part of the fixing roller 30. A heating element (heating source) 24 composed of a halogen lamp or the like is provided. The heating element 24 is dimensioned so as not to come into contact with the inner peripheral surface of the fixing roller 30. When power from an unillustrated power source is supplied to the heating element 24 via the connector 25 and the terminal block 23, the heating element 24 generates heat, and thereby the fixing roller 30 is heated. It has become.

  FIG. 3 is a view for explaining the first embodiment of the fixing roller 30. FIG. 3A is a perspective view showing a state in which the annular heat insulating member 40, the annular gear 50 and the bearing 60 are removed from the fixing roller 30. (B) is an enlarged perspective view showing the first embodiment of the annular heat insulating member 40. 4 is a perspective view showing a state in which the annular heat insulating member 40, the annular gear 50, and the bearing 60 are attached to the fixing roller 30, and FIG. 5 is a cross-sectional view taken along the line AA in FIG. As shown in these drawings, the fixing roller 30 is provided with an annular heat insulating member 40, an annular gear 50 and a bearing 60.

  First, as shown in FIG. 3A, the fixing roller 30 is a thin metal cylinder, and in the present embodiment, the outer diameter is set to 31.4 mm in diameter, and the thickness is set. The dimension is set to 0.35 mm, whereby the heating process of the fixing roller 30 by the heating element 24 is performed quickly, and the fixing device 20 is quickly started up when the power switch of the printer 10 is turned on. ing. The fixing roller 30 is provided with locking holes 31 at appropriate positions on both ends. These locking holes 31 are used to lock an annular heat insulating member 40 (described later) fitted on the fixing roller 30 in a non-rotating state.

  An annular heat insulating member 40, an annular gear 50, and a bearing 60 are fitted on the front side of the fixing roller 30 in FIG. 3, while the annular heat insulating member 40 and the bearing 60 are provided on the opposite side. Are externally fitted (see FIG. 5). On the front side of the fixing roller 30 in FIG. 3, the annular gear 50 and the bearing 60 that are loosely fitted to the fixing roller 30 in advance after the annular heat insulating member 40 is fitted to the fixing roller 30 are outside the annular heat insulating member 40. It is designed to be fitted. On the other hand, on the other side of the fixing roller 30 in FIG. 3, only the bearing 60 that is loosely fitted in advance to the fixing roller 30 after the annular heat insulating member 40 is fitted to the fixing roller 30 is attached to the annular heat insulating member 40. It is designed to be fitted.

  As shown in FIG. 3B, the annular heat insulating member 40 includes a heat insulating member main body 41 having an inner diameter dimension slightly smaller than the outer dimension of the fixing roller 30, and one end of the heat insulating member main body 41. And a flange 42 formed concentrically on the part. In the present embodiment, a slit 43 formed by cutting a part of the annular heat insulating member 40 over the entire length in the cylinder center direction is provided, and the slit 43 is provided in the middle of the slit 43. The 1st latching protrusion 44 protruded toward the inner side of radial direction from the inner peripheral surface of the heat insulation member main body 41 in the state of being bisected via is provided.

  The installation position of the first locking projection 44 is set corresponding to the locking hole 31 of the fixing roller 30. Then, the annular heat insulating member 40 is fitted into the fixing roller 30 with the annular heat insulating member 40 being slightly opened through the slit 43 and the first locking projections 44 that are split into two are inserted into the locking holes 31. Is attached to the fixing roller 30 in a non-rotating state.

  Further, the peripheral surface of the heat insulating member main body 41 is formed by being recessed from the edge opposite to the flange 42 until it substantially reaches the flange 42 in parallel with the cylindrical direction, and one end is an open end. A locking groove 45 is provided. The locking groove 45 is used to prevent the annular gear 50 fitted on the heat insulating member main body 41 from rotating.

  Further, an annular taper portion 411 ((b) in FIG. 3) that is inclined outward from the outer peripheral surface toward the axial center is formed at the end edge of the heat insulating member main body 41 opposite to the side on which the flange 42 is provided. The annular gear 50 and the bearing 60 are formed, and can be easily fitted into the heat insulating member main body 41 by being guided by the annular tapered portion 411.

  The annular gear 50 is set to have an inner diameter dimension slightly larger than an outer diameter dimension of the heat insulating member main body 41, so that the annular gear 50 can be fitted onto the heat insulating member main body 41 in a sliding state. On the inner peripheral surface of the annular gear 50, as shown in FIG. 3A, a second locking projection 51 corresponding to the locking groove 45 of the annular heat insulating member 40 protrudes toward the center. ing. The annular gear 50 is pushed into the heat insulating member main body 41 toward the flange 42 in a state where the second locking protrusions 51 are made to correspond to the locking grooves 45 of the annular heat insulating member 40, whereby the annular gear 50 is moved as shown in FIG. As shown in FIG. 4, the annular heat insulating member 40 fitted on the fixing roller 30 is attached in a non-rotating state.

  The bearing 60 is supported by the back plate 211 and the front plate 212 of the housing 21 (FIG. 2) in a state where the fixing roller 30 is rotatably supported around the cylinder center via the annular heat insulating member 40. It is. The bearing 60 is press-fitted into the annular heat insulating member 40 in a state where the inner diameter dimension is set to be substantially the same as the outer dimension of the heat insulating member body 41 and the annular gear 50 is fitted over the fixing roller 30 via the annular heat insulating member 40. It has become so.

  The annular heat insulating member 40 and the bearing 60 are fitted on both ends of the fixing roller 30 on the near side and the far side in FIG. 2, whereas the annular gear 50 is on the near end of the fixing roller 30. It is externally fitted only to the part, and is not externally fitted to the other end.

  In the state in which the annular heat insulating member 40 and the annular gear 50 and the bearing 60 are externally fitted through the annular heat insulating member 40 on the front side of the fixing roller 30 in FIG. 3, as shown in FIG. The first locking projection 44 is fitted in the locking hole 31 of the fixing roller 30 and the second locking projection 51 of the annular gear 50 is fitted in the locking groove 45 of the annular heat insulating member 40. Eventually, the fixing roller 30 and the annular gear 50 are coupled to each other via the annular heat insulating member 40 in a non-rotating state. Accordingly, when the driving roller 22 is driven and rotated by driving of a driving motor (not shown) with the fixing roller 30 mounted on the casing 21, the annular gear 50 meshing with the driving gear 22 also rotates, thereby the fixing roller. 30 will also rotate.

  According to the fixing roller 30 of the first embodiment and the annular heat insulating member 40 and the annular gear 50 mounted on the fixing roller 30, the first locking protrusion corresponding to the locking hole 31 of the fixing roller 30 is provided on the annular heat insulating member 40. 44 and a locking groove 45 corresponding to the second locking projection 51 of the annular gear 50, the fixing roller 30 is made of a thin wall, thereby preventing the fixing roller 30 from rotating. Even if it is difficult to perform various processes, the annular gear 50 can be attached to the fixing roller 30 through the annular heat insulating member 40 in a non-rotating state.

  FIG. 6 is an exploded perspective view showing a second embodiment of the fixing roller 30a, the annular heat insulating member 40a, and the annular gear 50a. In this embodiment, a pair of locking holes 31 are formed at positions opposed to the end of the fixing roller 30a, and the annular heat insulating member 40a is formed by combining the pair of divided bodies 46 together. It has become. Further, the annular gear 50 a has a pair of second locking protrusions 51 that respectively project from opposing positions on the inner peripheral surface so as to correspond to the pair of divided bodies 46.

  Each of the divided bodies 46 includes a semicircular divided body 41a and a semicircular flange 42a formed on one end edge of the divided body 41a. A first locking projection 44 corresponding to the locking hole 31 of the fixing roller 30a is projected at the central portion in the circumferential direction of curvature on the inner surface side of the divided body 41a, and the central portion in the circumferential direction of curvature on the outer surface side. A locking groove 45 into which the second locking projection 51 of the annular gear 50a is fitted is recessed in the part.

  Further, chamfered edges 411b extending in the cylinder center direction formed by the chamfering process are provided on the radially outer edges of the opposing surfaces of the respective divided bodies 46, whereby the pair of divided bodies 46 are combined. In the annular heat insulating member 40a formed as a result, a steep step is prevented from being formed at the opposing portion of both.

  In addition, an arcuate taper portion 411a corresponding to the annular taper portion 411 of the first embodiment is provided at the end edge portion of the heat insulating member main body 41 on the side opposite to the semicircular flange 42a. The annular gear 50a and the bearing 60 are easily fitted into the annular heat insulating member 40a formed by being attached to the fixing roller 30a.

  Further, the inner diameter of the curvature of each divided body 46 is set slightly smaller than the outer diameter of the fixing roller 30a. In this manner, the annular gear 50a and the bearing 60 are externally fitted to each divided body 41a in a state where the pair of divided bodies 46 are respectively covered with the fixing roller 30a to form the annular heat insulating member 40a. Is elastically deformed and expanded in diameter, and thereby the inner surface of each divided body 41a is pressed and brought into close contact with the peripheral surface of the fixing roller 30a. Therefore, the annular gear 50a and the fixing roller of the bearing 60 via the annular heat insulating member 40a. The mounting state to 30a is stabilized.

  In addition, each of the divided body bodies 41a is set so that the central angle of curvature is slightly smaller than 180 °, so that the pair of divided bodies 46 are mounted on the fixing roller 30a. A slight gap is formed. By doing so, a problem in the mounting state due to a dimensional error at the time of manufacturing the divided body 46, specifically, the inner surface of the divided body 46 comes into close contact with the peripheral surface of the fixing roller 30a due to the contact of the opposing surfaces of the divided bodies 46. Occurrence of problems such as disappearance can be prevented.

  According to the fixing roller 30a, the annular heat insulating member 40a, and the annular gear 50a of the second embodiment configured as described above, each divided body 46 can be attached to the fixing roller 30a so that the annular heat insulating member can be mounted. The mounting operation for the fixing roller 30a of 40a is facilitated.

  FIG. 7 is an exploded perspective view showing a third embodiment of the annular heat insulating member 40b. The fixing roller 30a and the annular gear 50a to which the annular heat insulating member 40b of the third embodiment is applied are the same as those of the second embodiment.

  As shown in FIG. 7, the annular heat insulating member 40b according to the third embodiment is formed by combining a pair of divided bodies 46a. Although it is the same as that of 2nd Embodiment in which the cyclic | annular heat insulation member 40a is formed, each edge part 46a has opposing edge parts in each edge part extended in a cylinder center direction, when the said pair of division body 46a is match | combined. The point from which the fitting structure 47 which mutually fits is provided differs from the thing of 2nd Embodiment.

  That is, the fitting structure 47 includes a rectangular fitting protrusion 471 projecting outward in the circumferential direction from one end edge surface extending in the cylinder center direction of the divided body 46a, and the other end. And a fitting recess 472 corresponding to the fitting protrusion 471 that is recessed from the edge surface inward in the circumferential direction. The fitting recess 472 is shaped slightly larger than the fitting protrusion 471, so that the fitting protrusion 471 of the other divided body 46a is fitted into the fitting recess 472 of one divided body 46a with a margin. ing. The structure of the other division body 46a is the same as that of the division body 46 of 2nd Embodiment.

  According to the annular heat insulating member 40b of the third embodiment configured as described above, a pair of divided bodies 46a are mounted on the fixing roller 30a, thereby forming one of the divided bodies 46a. Since the fitting protrusions 471 are fitted into the fitting recesses 472 of the other divided body 46a, the displacement of each divided body 46a toward the cylinder center direction is reliably prevented, thereby the fixing roller 30a and the annular gear. The mounting state of the annular heat insulating member 40b interposed between the fixing roller 30a and the annular heat insulating member 40b is stabilized.

  As described above in detail, the fixing device 20 according to the present invention includes a fixing roller 30 and 30a that is rotatable about an axis and includes a heating element 24 that is a heating source, and a fixing roller 30 and 30a that have a peripheral surface. The sheet P is supplied to a nip portion N formed between a pressure roller 70 rotatable around a roller shaft 71 extending in the same direction as the axis of the fixing rollers 30 and 30a in a state of being pressed against the peripheral surface of As a result, the toner image on the paper P is subjected to a fixing process by heating. Therefore, between the fixing rollers 30 and 30a and the pressure roller 70 rotating the paper P in opposite directions. By feeding the sheet P to the nip portion N formed in the sheet P, the sheet P is conveyed while being subjected to fixing processing for the toner image by obtaining heat from the fixing rollers 30 and 30a having heat sources therein. Discharged from Fixed by the ends.

  In such a fixing device 20, the first heat-insulating protrusions projecting in the radial direction from the inner peripheral surface of the annular heat insulating members 40, 40a, 40b concentrically fitted to the fixing rollers 30, 30a. 44, the fixing rollers 30 and 30a are provided with the locking holes 31 into which the first locking projections 44 are fitted. Therefore, the annular heat insulating members 40, 40a and 40b are connected to the fixing rollers 30 and 30a. And the first heat-insulating members 40, 40a, 40b are fitted into the retaining holes 31 of the fixing rollers 30, 30a to prevent the heat-insulating members 40, 40a, 40b from rotating. It can be attached to the fixing rollers 30 and 30a in a state.

  Therefore, even if the fixing rollers 30 and 30a are thin, and the conventional anti-rotation key surface cannot be cut on the fixing rollers 30 and 30a, the annular heat insulating members 40, 40a and 40b are provided. While the first locking projection 44 is provided on the side, the annular heat insulating member 40, 40a, 40b is reliably prevented from rotating by providing the locking hole 31 corresponding to the first locking projection 44 on the fixing roller 30, 30a side. Can be attached to the fixing rollers 30 and 30a, thereby making it possible to reduce the thickness of the fixing rollers 30 and 30a as much as possible. Therefore, the heat transfer efficiency can be improved and the image forming apparatus can be quickly turned on. Can contribute to a successful start-up.

  Further, annular gears 50, 50a are fitted on the annular heat insulating members 40, 40a, 40b so as to drive and rotate the fixing rollers 30, 30a around the axis, and the annular gears 50, 50a are provided from the inner peripheral surface. On the other hand, the second locking projections 51 projecting in the radial direction are provided, while the annular locking members 40, 40a, 40b are fitted with the second locking projections 51, extend in the axial direction, and Since the locking groove 45 having an open end is provided, the second locking projection 51 protruding from the inner peripheral surface of the annular gears 50, 50a is formed on the annular heat insulating members 40, 40a, 40b. The annular gears 50 and 50a are attached to the annular heat insulating members 40, 40a, and 40b in a non-rotating state by being fitted into the provided locking grooves 45 extending in the axial direction from the open ends. Thus, the annular gears 50, 50a are fitted into the annular heat insulating members by fitting the second locking projections 51 into the locking grooves 45 with respect to the annular heat insulating members 40, 40a, 40b in the state of being previously attached to the fixing rollers 30, 30a. The fixing rollers 30 and 30a can be integrated with each other through 40, 40a and 40b, whereby the driving force of a predetermined driving means can be transmitted to the fixing rollers 30 and 30a through the annular gears 50 and 50a. .

  Particularly in the second and third embodiments, the annular heat insulating members 40a and 40b are configured to be divided into a plurality of divided bodies 46 and 46a in the circumferential direction. By assembling the bodies 46 and 46a, the annular heat insulating members 40a and 40b are attached to the fixing roller 30a, and the workability of assembling the annular heat insulating members 40, 40a and 40b to the fixing roller 30a can be improved. it can.

  Since each of the divided bodies 46a is formed with a fitting structure 47 that is fitted to each other on the opposing surfaces of the one divided body 46a and the other divided body 46a, the combined state of the divided bodies 46a is stabilized. Can be made.

  In addition, since each of the divided bodies 46a is dimensioned so that a gap is formed on the opposite surface when mounted on the fixing roller 30a, the divided bodies 46a are adjacent to each other with the divided bodies 46a assembled around the fixing roller 30a. Spatial margins can be made between the divided bodies 46a, which can prevent problems in the mounting state due to dimensional errors during manufacturing and the like, and the annular heat insulating members 40a and 40b are securely mounted to the fixing roller 30a. Can do.

  Further, since each of the divided bodies 46a is set so that the inner diameter of the curvature is smaller than the outer diameter of the fixing roller 30a, the divided bodies 46a are mounted around the fixing roller 30a to form the annular heat insulating members 40a and 40b. In this state, the annular gears 50, 50a are press-fitted into the annular heat insulating members 40, 40a, 40b, so that each divided body 46a is elastically deformed so that the radius of curvature becomes large, and the fixing roller 30a is caused by this elastic force. This makes it possible to stabilize the mounting state of each divided body 46a on the fixing roller 30a.

  In addition, since each divided body 46a has a chamfered edge 411b formed at the radially outer edge portion of the opposing surface, even if the divided bodies 46a are assembled around the fixing roller 30a, adjacent divided parts due to manufacturing errors. Even if a step is formed between the outer surfaces of the body 46a, the steep step between the outer surfaces of the adjacent divided bodies 46a is alleviated by the chamfered edge 411b, and the annular gears 50 and 50a are connected. It can be easily fitted into the annular heat insulating members 40a, 40b made up of the respective divided bodies 46a, and the workability of the assembling work can be improved.

  In addition to these, at one end of the annular heat insulating members 40, 40a, 40b (the end on the side where the annular gears 50, 50a are fitted), an annular taper inclined outward from the outer peripheral surface toward the axis. Since the portions 411, 411a are formed, when the annular gears 50, 50a are fitted into the annular heat insulating members 40, 40a, 40b attached to the fixing roller 30a, the annular gears 50, 50a are connected to the annular heat insulating members 40, 40a. , 40b is guided by an annular tapered portion 411 formed at one end of the annular gears 50, 50b, thereby improving the workability of the mounting operation of the annular gears 50, 50a on the annular heat insulating members 40, 40a, 40b.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the printer 10 is described as an example of the image forming apparatus to which the fixing device 20 is applied. However, the present invention is limited to the printer 10 as the image forming apparatus. Instead, it may be a copying machine or a facsimile machine.

  (2) In the first embodiment described above, the first locking projections 44 are provided in a divided state with the slits 43 sandwiched between the inner peripheral surface of the annular heat insulating member 40. The protrusion 44 is not limited to being provided in a divided state with the slit 43 interposed therebetween, and may be provided in a state where the protrusion 44 is not divided at a position away from the slit 43.

  (3) In the third embodiment described above, the shape of the fitting projection 471 and the fitting recess 472 of the fitting structure 47 is set to a rectangular shape. The shape 472 is not limited to a rectangular shape, and may be other shapes such as a triangular shape or a semicircular shape.

  (4) In the second and third embodiments, the annular heat insulating members 40a and 40b can be divided into two parts 46 and 46a. However, in the present invention, the annular heat insulating members 40a and 40b are divided into two parts. It is not limited to being able to divide into two division bodies 46 and 46a, and may be divided into three or more.

  (5) FIG. 8 is a perspective view showing a modification of the annular heat insulating member 40b (FIG. 7) of the third embodiment. In this modified example, the contact positions of the respective divided bodies 46a, 46a (specifically, the positions at which the fitting protrusions 471 of one divided body 46a and the fitting recesses 472 of the other divided body 46a fit each other) The flat portion 48 formed flat is provided on the outer surface side in ().

  By providing such a flat portion 48, even if a step is present on the outer surface side of the contact position of each of the divided bodies 46a and 46a, which are constituent elements of the annular heat insulating member 40b, this portion is flat. Therefore, when the annular gear 50 and the bearing 60 are externally fitted to the annular heat insulating member 40b, there is no inconvenience that it is difficult to fit the annular gear 50 and the bearing 60 to the annular heat insulating member 40b. It can be externally fitted, and as a result, can contribute to the improvement of workability of the assembling work of the fixing device 20.

1 is a front sectional view illustrating an outline of an internal structure of an embodiment of a printer that is a type of an image forming apparatus to which a fixing device according to the invention is applied. FIG. 3 is a perspective view illustrating the embodiment of the fixing device as viewed from the back side. 2A and 2B are views for explaining a first embodiment of a fixing roller, in which FIG. 1A is a perspective view showing a state in which a bearing, an annular gear, and an annular heat insulating member are removed from the fixing roller, and FIG. It is an expansion perspective view which shows 1st Embodiment of this. FIG. 3 is an assembled perspective view of a fixing roller. It is the sectional view on the AA line of FIG. It is a disassembled perspective view which shows 2nd Embodiment of a fixing roller, a cyclic | annular heat insulation member, and a cyclic | annular gear. It is a disassembled perspective view which shows 3rd Embodiment of an annular heat insulation member. It is a perspective view which shows the modification of the cyclic | annular heat insulation member of 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printer 11 Apparatus main body 12 Paper storage part 121 Paper cassette 122 Pickup roller 123 Paper feed conveyance path 124 Registration roller pair 13 Image forming part 130 Photosensitive unit 131 Photosensitive drum 132 Charger 133 Exposure device 134 Developing device 135 Transfer roller 136 Cleaning Device 136a Rub roller 14 Fixing unit 141 Paper delivery path 15 Paper delivery unit 151 Paper delivery tray 16 Blower 161 Filter 17 Air duct 20 Fixing device 21 Housing 211 Rear plate 212 Front plate 213 Side plate member 22 Drive gear 221 Gear shaft 23 Terminal block 24 Heating element (heating source)
25 Connector 30, 30a Fixing roller 31 Locking hole 40 Annular heat insulating member 40a, 40b Annular heat insulating member 41 Heat insulating member main body 41a Divided body main body 411 Annular taper part 411a Arc-shaped taper part 411b Chamfered edge 42 Flange 42a Semicircular flange 43 Slit 44 Locking protrusion 45 Locking groove 46, 46a Divided body 47 Fitting structure 471 Fitting protrusion 472 Fitting recess 48 Flat part 50 Ring gear 50a Ring gear 51 Locking protrusion 60 Bearing 70 Pressure roller 71 Roller shaft N Nip part P Paper (recording medium) P1 Paper bundle V Installation space

Claims (9)

A fixing device that heats a toner image on a recording medium by supplying the recording medium to a peripheral surface of a fixing roller that is rotatable about an axis and includes a heating source,
The fixing roller is provided with an annular heat insulating member fitted concentrically,
The annular heat insulating member is provided with a first locking protrusion protruding in the radial direction from the inner peripheral surface, while the fixing roller is engaged with the first locking protrusion. A fixing device having holes. An annular gear is externally fitted to the annular heat insulating member so as to drive and rotate the fixing roller about its axis.
The annular gear is provided with a second locking projection protruding in the radial direction from the inner peripheral surface, while the annular heat insulating member is fitted with the second locking projection. The fixing device according to claim 1, further comprising a locking groove extending in a direction and having an open end at one end.   The fixing device according to claim 1, wherein the annular heat insulating member is configured to be divided into a plurality of divided bodies in a circumferential direction.   The fixing device according to claim 3, wherein each of the divided bodies is formed with a fitting structure that fits to each other on mutually facing surfaces.   5. The fixing device according to claim 3, wherein each of the divided bodies is dimensioned so that a gap is formed on an opposing surface in a state of being mounted on the fixing roller.   6. The fixing device according to claim 3, wherein each of the divided bodies has a curvature inner diameter dimension smaller than an outer diameter dimension of the fixing roller.   The fixing device according to claim 3, wherein each of the divided bodies is subjected to chamfering treatment on a radially outer edge portion of a surface facing each other.   The fixing device according to claim 3, wherein each of the divided bodies is formed to have a flat outer surface side at a contact position.   9. The fixing according to claim 1, wherein an annular taper portion that is inclined outwardly from the outer peripheral surface toward the axial center is formed at one end portion of the annular heat insulating member. apparatus.

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