JP2018055027A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To normally drive a heating roller or suppress the generation of an abnormal sound.SOLUTION: A fixing device 18 includes a first bearing B1 and a second bearing B2 which rotatably support a heating roller 41. The first bearing B1 comes into contact with a first part 41A located on one side in the axial direction of the heating roller 41. The second bearing B2 comes into contact with a second part 41B located on the other side in the axial direction of the heating roller 41. The first part 41A has a first intermittent contact area 61 whose movement in the axial direction with respect to the first bearing B1 is regulated and which comes into intermittent contact with the first bearing B1. The second part 41B has a second intermittent contact area 71 which comes into intermittent contact with the second bearing B2. A distance from the second intermittent contact area 71 to the edge E2 on the other side of the second bearing B2 is larger than a distance from the first intermittent contact area 61 to the edge E1 on the other side of the first bearing B1.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fixing device for thermally fixing a toner image on a sheet.

  Conventionally, a fixing device including a heating roller, a bearing that rotatably supports an end portion of the heating roller, and a heat insulating material provided between the end portion of the heating roller and the bearing is known ( Patent Document 1). Specifically, in this technique, a groove is formed on the surface of the heat insulating material facing the bearing. Thereby, since the contact area of a heat insulating material and a bearing becomes small, it is suppressed that the heat of a heating roller escapes to a bearing through a heat insulating material.

Japanese Patent Laid-Open No. 2006-40599

  By the way, in order to increase the heat insulation efficiency of the heat insulating material, it is desirable to make the region where the groove of the heat insulating material is formed as large as possible in the axial direction of the heating roller. However, if the groove forming area is enlarged, for example, when the heating roller thermally expands in the axial direction, the groove may move outward in the axial direction with respect to the bearing. And when the groove moves in the axial direction outside of the bearing in this way, for example, a part of the end of the bearing overlaps with the groove, the end of the bearing is not reliably contacted and supported by the blank tube, and the bearing is tilted, etc. As a result, there is a possibility that problems such as failure of normal driving or generation of abnormal noise may occur. Further, in the prior art, since a heat insulating material is provided between the heating roller and the bearing, there is a problem that the cost increases.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of normally driving a heating roller or suppressing occurrence of abnormal noise. The second object of the present invention is to reduce the cost.

In order to solve the above problems, a fixing device according to the present invention includes a heat source, a heating roller heated by the heat source, and a first bearing and a second bearing that rotatably support the heating roller.
The first bearing contacts a first portion located on one side in the axial direction of the heating roller.
The second bearing contacts a second portion located on the other side of the heating roller in the axial direction.
The first portion has a first intermittent contact region that is restricted from moving in the axial direction with respect to the first bearing and intermittently contacts the first bearing.
The second portion has a second intermittent contact region that intermittently contacts the second bearing.
The distance from the second intermittent contact region to the other edge in the axial direction of the second bearing is the distance from the first intermittent contact region to the other edge in the axial direction of the first bearing. Is bigger than.

  According to this structure, when the heating roller is thermally expanded in the axial direction, the second portion on the free end side is more axially positioned than the first portion on the fixed end side by stacking of the thermal expansion of each part of the heating roller. Even if it moves largely to the other side, it is possible to prevent the concave portion constituting the second intermittent contact region from moving to the other edge of the second bearing, so that the heating roller can be driven normally or differently. Generation of sound can be suppressed.

  According to the present invention, the heating roller can be driven normally or abnormal noise can be suppressed.

1 is a cross-sectional view illustrating a laser printer including a fixing device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view (a) showing a fixing device and a view (b) showing an engagement ring. It is a perspective view which shows the groove | channel of a 1st intermittent contact area | region. It is sectional drawing (a) which expands and shows the circumference | surroundings of a 1st part, and sectional drawing (b) which expands and shows the circumference | surroundings of a 2nd part. It is a graph which shows distribution of the emitted-heat amount of a halogen lamp. It is sectional drawing which shows the relationship between the 2nd intermittent contact area | region at the time of thermal expansion, and a 2nd bearing. FIG. 9 is a cross-sectional view illustrating a fixing device according to Modification Example 1. FIG. 6 is a cross-sectional view (a) showing a fixing device according to Modification 2 and a cross-sectional view (b) showing a fixing device according to Modification 3.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the laser printer 1 includes a feeder unit 4 for feeding the paper 3 into the main body housing 2 and an image forming unit 5 for forming an image on the fed paper 3. I have.

  The feeder unit 4 mainly includes a paper feed tray 6 that is detachably attached to the lower part of the main body housing 2 and a paper supply mechanism 7 that transports the paper 3 from the paper feed tray 6 to the image forming unit 5. Yes.

  The image forming unit 5 includes a scanner unit 16, a process cartridge 17, and a fixing device 18.

  The scanner unit 16 is provided in the upper part of the main body housing 2 and includes a laser light emitting unit (not shown), a polygon mirror 19 that is rotationally driven, lenses 20, 21 and reflecting mirrors 22, 23, 24, and the like. Yes. In the scanner unit 16, the laser beam is irradiated on the surface of the photosensitive drum 27 of the process cartridge 17 by high-speed scanning through a path indicated by a chain line in the drawing.

  The process cartridge 17 is disposed below the scanner unit 16 and is configured to be detachably attached to the main body housing 2. The process cartridge 17 includes a photosensitive drum 27, a charger 29, a transfer roller 30, a developing roller 31, a layer thickness regulating blade 32, a supply roller 33, a toner hopper 34, and the like.

  In the process cartridge 17, the surface of the photosensitive drum 27 charged by the charger 29 is exposed with a laser beam from the scanner unit 16, whereby an electrostatic latent image is formed on the photosensitive drum 27. A toner image is formed on the photosensitive drum 27 by supplying toner in the toner hopper 34 to the electrostatic latent image via the supply roller 33 and the developing roller 31. Thereafter, when the sheet 3 is conveyed between the photosensitive drum 27 and the transfer roller 30, the toner image on the photosensitive drum 27 is attracted to the transfer roller 30 and transferred to the sheet 3.

  The fixing device 18 mainly includes a halogen lamp 43 as an example of a heat source, a heating roller 41, and a pressure roller 42. The detailed structure of the fixing device 18 will be described in detail later.

  The halogen lamp 43 is disposed in a cylindrical heating roller 41 and heats the heating roller 41 from the inside.

  The heating roller 41 is a metal member formed in a substantially cylindrical shape, and is rotatably disposed above the pressure roller 42.

  The pressure roller 42 is in pressure contact with the heating roller 41, and is in contact with the rotating heating roller 41 to rotate following. As the pressure roller 42, for example, a silicon rubber provided around the core metal and the surface of the silicon rubber covered with a PTFE tube can be used.

  In the fixing device 18, the heating roller 41 is heated by the halogen lamp 43, so that the toner image transferred to the sheet 3 while the sheet 3 passes between the heating roller 41 and the pressure roller 42 is transferred. Heat-fixed. Thereafter, the sheet 3 is conveyed to a sheet discharge path 44 by a conveyance roller (not shown), and is discharged onto a sheet discharge tray 46 by a sheet discharge roller 45.

  As shown in FIG. 2A, in addition to the heating roller 41 and the halogen lamp 43 described above, the fixing device 18 includes a first bearing B1 and a second bearing B2 that rotatably support the heating roller 41, and a first bearing B1. A housing 50 that supports the bearing B1 and the second bearing B2 and a temperature detector TS that detects the temperature of the heating roller 41 are provided.

  The first bearing B1 is a metal ball bearing, and a plurality of annular outer races B11, an annular inner race B12 provided inside the outer race B11, and a plurality of portions provided between the outer race B11 and the inner race B12. And the ball B13. The outer race B11 is fixed to the housing 50. The inner race B12 is rotatable with respect to the outer race B11 by the rolling of the ball B13. The first bearing B1 is grounded via a metal member or wiring HW provided in the housing 50.

  The second bearing B2 is a metal ball bearing similar to the first bearing B1. Specifically, the dimension of the second bearing B2 in the axial direction is the same as the dimension of the first bearing B1 in the axial direction. The second bearing B2 mainly includes an outer race B21, an inner race B22, and a plurality of balls B23 similar to the first bearing B1. The first bearing B1 is disposed on one side of the heating roller 41 in the axial direction, and the second bearing B2 is disposed on the other side of the heating roller 41 in the axial direction. In the following description, for the sake of convenience, the axial direction is also referred to as “left-right direction”, one side in the axial direction is also referred to as “left side”, and the other side in the axial direction is also referred to as “right side”.

  The temperature detector TS is located near the right end of the heating roller 41. Specifically, the temperature detector TS is disposed on the left side of the second bearing B <b> 2 and is supported by the housing 50.

  The halogen lamp 43 includes a first coil part 43A disposed at the center in the left-right direction of the heating roller 41, a second coil part 43B disposed on the left side of the first coil part 43A, and a right side of the first coil part 43A. It has the 3rd coil part 43C arranged. The second coil part 43B is wound more densely than the first coil part 43A. The third coil portion 43C is wound more densely than the second coil portion 43B.

  As a result, as shown in FIG. 5, the heat generation amount on the left side of the heat generation amount (output heat amount) of the halogen lamp 43 is lower than the heat generation amount on the right side. Here, the left side (one side in the axial direction) and the right side (the other side in the axial direction) are bordered by the center of the heating roller 41 in the left-right direction and / or the paper transport center (the center in the left-right direction of the transported paper). Means one side and the other side.

  Returning to FIG. 2A, the heating roller 41 includes a metal base tube 411 and a heat insulating layer 412 having a higher heat insulating property than the base tube 411. The raw tube 411 is made of, for example, aluminum. The heat insulating layer 412 is formed on a part of the outer peripheral surface of the cylindrical element tube 411. Specifically, the heat insulating layer 412 is formed from a portion of the element tube 411 slightly away from the first bearing B1 to the right end of the element tube 411. In other words, the left end of the heat insulating layer 412 is disposed between the center of the heating roller 41 in the left-right direction and the first bearing B1, and closer to the first bearing B1 than the center of the heating roller 41. ing. The heat insulating layer 412 is a layer of fluororesin (polytetrafluoroethylene (PFA), polytetrafluoroethylene (PTFE), etc.), and may be a tube or a coating. The heat insulating layer 412 has a lower thermal conductivity than the base tube 411.

  When the heating roller 41 composed of such a raw tube 411 and the heat insulating layer 412 is considered as a plurality of parts divided in the left-right direction, the heating roller 41 is configured by a plurality of parts described below.

  The heating roller 41 extends from the first portion 41A to the second portion 41B, the first portion 41A that contacts the inner race B12 of the first bearing B1, the second portion 41B that contacts the inner race B22 of the second bearing B2. It has a third portion 41C, a fourth portion 41D extending to the left from the first portion 41A, and a fifth portion 41E extending to the right from the second portion 41B. The first portion 41A and the fourth portion 41D have a raw tube 411, and the third portion 41C, the second portion 41B and the fifth portion 41E have a raw tube 411 and a heat insulating layer 412. That is, the first portion 41 </ b> A does not have the heat insulating layer 412, and the second portion 41 </ b> B has the heat insulating layer 412. The first portion 41A is in direct contact with the inner race B12 of the first bearing B1. Of the second portion 41B, the portion made of the raw tube 411 is in contact with the inner race B22 of the second bearing B2 via the heat insulating layer 412.

  The first portion 41A is located near the left end of the heating roller 41 and is fitted to the inner peripheral surface of the inner race B12 of the first bearing B1. The second portion 41B is located near the right end of the heating roller 41 and is fitted to the inner peripheral surface of the inner race B22 of the second bearing B2. The strength of the fitting is such that the heating roller 41 can move relative to the inner races B12 and B22 when the heating roller 41 is thermally expanded in the left-right direction.

  The first portion 41 </ b> A is restricted from moving in the left-right direction with respect to the first bearing B <b> 1 by a gear G <b> 1, a washer W, and an engagement ring R provided on the heating roller 41. The gear G1, the washer W, and the engagement ring R are made of metal or resin.

  The gear G1 is disposed on the left side of the first bearing B1 and is fixed to the fourth portion 41D. The gear G1 has a main body part G11 having gear teeth formed on the outer peripheral part, and a protruding part G12 protruding from the right end surface of the main body part G11. And the front-end | tip of the protrusion part G12 is contacting the inner race B12 of the 1st bearing B1. This restricts the heating roller 41 (first portion 41A) from moving to the right.

  The washer W is an annular member that allows the heating roller 41 to pass through, and is disposed on the right side of the first bearing B1. As shown in FIG. 2B, the engagement ring R is a C-shaped member in plan view, and has a plurality of engagement portions R1 protruding inward in the radial direction.

  As shown in FIG. 2 (a), the engagement ring R is disposed on the right side of the washer W, and each engagement portion R 1 is engaged with a plurality of engagement holes 413 formed in the heating roller 41. Match. As a result, the engagement ring R is fixed to the heating roller 41, so that the engagement ring R contacts the inner race B12 of the first bearing B1 via the washer W even if the heating roller 41 tries to move to the left side. Thus, the movement of the heating roller 41 is restricted.

  In addition, the first portion 41A has a first intermittent contact region 61 that intermittently contacts the inner race B12 of the first bearing B1. As shown in FIG. 3, the first intermittent contact region 61 has a spiral groove 61 </ b> A along the circumferential direction of the heating roller 41. The groove 61A may be formed by cutting or may be formed by pressing. As shown in FIG. 4A, the first intermittent contact region 61 is a region from the left end to the right end of the spiral groove 61A in the outer peripheral surface of the first portion 41A. The area | region in which the groove | channel 61A is not formed among the 1st intermittent contact area | regions 61 becomes the spiral contact part 61B which contacts the inner peripheral surface of the inner race B12.

  In the cross-sectional view of FIG. 4A, that is, a cross-sectional view of the first portion 41A cut along a plane passing through the axis of the heating roller 41, the first intermittent contact region 61 includes a plurality of recesses arranged at intervals in the left-right direction. Have. Thereby, the 1st intermittent contact area | region 61 is contacting the inner peripheral surface of the inner race B12 intermittently. If the first intermittent contact region 61 is defined by the plurality of concave portions described above, the first intermittent contact region 61 is a region from the left end of the leftmost concave portion to the right end of the rightmost concave portion. .

  Of the outer peripheral surface of the first portion 41A, the left and right portions of the first intermittent contact region 61 are continuous contact portions 62 and 63 that continuously contact the inner peripheral surface of the inner race B12. And the part which match | combined each continuous contact parts 62 and 63 and the helical contact part 61B among the outer peripheral surfaces of 1st part 41A is the 1st contact surface F1 which contacts the inner race B12 of 1st bearing B1. It has become.

  As shown in FIG. 4B, the second portion 41B has a second intermittent contact region 71 that intermittently contacts the inner race B22 of the second bearing B2. The second intermittent contact region 71 has a spiral groove 71 </ b> A along the circumferential direction of the heating roller 41. The second intermittent contact region 71 is a region from the left end to the right end of the spiral groove 71A in the outer peripheral surface of the second portion 41B. The area | region where the groove | channel 71A is not formed among the 2nd intermittent contact area | regions 71 becomes the spiral contact part 71B which contacts the inner peripheral surface of the inner race B22. The groove 71A of the second intermittent contact region 71 is different from the groove 61A of the first intermittent contact region 61 in the left-right direction, and the other depth, width, and pitch are the same as the groove 61A of the first intermittent contact region 61. It has become.

  In the cross-sectional view of FIG. 4B, that is, a cross-sectional view of the second portion 41B taken along the plane passing through the axis of the heating roller 41, the second intermittent contact region 71 includes a plurality of concave portions arranged at intervals in the left-right direction. Have. Thereby, the 2nd intermittent contact area | region 71 is contacting the inner peripheral surface of the inner race B22 intermittently. If the second intermittent contact region 71 is defined by the plurality of concave portions described above, the region from the left end of the leftmost concave portion to the right end of the rightmost concave portion is the second intermittent contact region 71. .

  Of the outer peripheral surface of the second portion 41B, the left and right side portions of the second intermittent contact region 71 are continuous contact portions 72 and 73 that continuously contact the inner peripheral surface of the inner race B22, respectively. And the part which match | combined each continuous contact parts 72 and 73 and the helical contact part 71B among the outer peripheral surfaces of the 2nd part 41B is the 2nd contact surface F2 which contacts the inner race B22 of 2nd bearing B2. It has become.

  As shown in FIGS. 4A and 4B, the horizontal dimension L1 of the first intermittent contact region 61 is larger than the horizontal dimension L4 of the second intermittent contact region 71. Thereby, the area of the first contact surface F1 is smaller than the area of the second contact surface F2.

  The horizontal dimensions L2, L3, L6 of the continuous contact portions 62, 63 in the first portion 41A and the continuous contact portion 73 on the left side in the second portion 41B are substantially the same, and the dimensions of the second intermittent contact region 71 are the same. It is sufficiently smaller than L4. Specifically, the dimensions L2, L3, and L6 of the continuous contact portions 62, 63, and 73 are substantially the same as the pitches of the plurality of recesses in the cross-sectional view of FIG. That is, the relationship between the dimensions is L3 <L5, L6 <L5, L1> L2, L1> L3, L5 <L4, L6 <L4. Grooves 61 </ b> A and 71 </ b> A are not formed in the range of dimensions L <b> 2, L <b> 3, L <b> 5, and L <b> 6, and the surface is smoother than the intermittent contact regions 61 and 71. This surface has a large amount of heat conduction to the bearings B1 and B2.

  The left-right dimension L5 of the right continuous contact portion 72 in the second portion 41B is larger than the left-right dimension L2 of the right continuous contact portion 62 in the first portion 41A. Thereby, the distance (L5) from the second intermittent contact region 71 to the right edge E2 of the second bearing B2 is the distance (L2) from the first intermittent contact region 61 to the right edge E1 of the first bearing B1. ) Is larger than. Here, the right edge E1, E2 of each bearing B1, B2 means the right edge of the inner peripheral surface of each inner race B12, B22, respectively. The relationship between the dimensions and distances described above is established at room temperature.

Next, the effect of this embodiment is demonstrated.
When the heating roller 41 is heated by the halogen lamp 43, the heating roller 41 is thermally expanded in the left-right direction. At this time, the first portion 41A, whose movement in the left-right direction is restricted, hardly moves due to thermal expansion and remains at the position shown in FIG. On the other hand, the second portion 41B that is not restricted to move in the left-right direction is placed on the right side from the position shown in FIG. 4B to the position shown in FIG. Move a lot. Even in this case, since the right and left dimension L5 of the right continuous contact portion 72 in the second portion 41B at the normal temperature is sufficiently large, the groove 71A (the rightmost portion of the second intermittent contact region 71) ) Can be suppressed from moving to the right edge E2 of the second bearing B2. As a result, it is possible to prevent the groove 71A from overlapping the right edge E2 of the second bearing B2 when the heating roller 41 is thermally expanded, so that the heating roller is driven normally or abnormal noise is generated. Can be suppressed. Here, that the groove 71A overlaps with the end edge E2 of the second bearing B2 means that a part of the groove 71A and the end edge E2 are located at the same position in the left-right direction.

As described above, according to the present embodiment, the following effects can be obtained in addition to the effects described above.
Since the area of the first contact surface F1 is smaller than the area of the second contact surface F2, it is possible to prevent heat from escaping from the first portion 41A to the first bearing B1.

  Of the calorific value of the halogen lamp 43, the calorific value on the left side is lower than the calorific value on the right side, so that a large amount of heat is given from the halogen lamp 43 to the second portion 41B side of the heating roller 41, that is, on the right side. . Therefore, even if heat escapes from the second portion 41B having the second contact surface F2 larger than the first contact surface F1 to the second bearing B2, the second portion 41B can be heated satisfactorily. Can reduce the heat bias in the horizontal direction

  Since the temperature detector TS is disposed on the right side of the heating roller 41 where a large amount of heat is applied from the halogen lamp 43, the temperature of the heating roller 41 can be detected well.

  Since the base tube 411 of the heating roller 41 has the first portion 41A and the second portion 41B, the number of parts is reduced as compared with, for example, a configuration in which a member different from the heating roller 41 as described later has the first portion and the like. be able to.

  Since the second portion 41B includes the heat insulating layer 412, heat dissipation from the second portion 41B to the second bearing B2 can be suppressed by the heat insulating layer 412.

  Since the 2nd part 41B with a large contact area with 2nd bearing B2 has the heat insulation layer 412, the thermal radiation from the heating roller 41 to the 2nd bearing B2 can be suppressed efficiently. In addition, since the first portion 41A does not have the heat insulating layer 412, the first portion 41A can be brought into direct contact with the first bearing B1, so that the electric charge charged in the base tube 411 of the heating roller 41 is changed to the first portion 41A. It can be dropped to the ground via the portion 41A and the first bearing B1.

  Since the heating roller 41 has the first intermittent contact region 61 and the second intermittent contact region 71, the number of parts can be reduced as compared with a mode in which the first intermittent contact region or the like is provided on a member different from the heating roller 41 as described later, for example. Can be reduced.

  In addition, this invention is not limited to the said embodiment, It can utilize with various forms so that it may illustrate below. In the following description, the same reference numerals are given to members having substantially the same structure as in the above embodiment, and the description thereof is omitted.

  In the above embodiment, the heating roller 41 has a structure having the first portion 41A and the second portion 41B. However, the present invention is not limited to this, and members other than the heating roller are the first portion and the second portion. You may have. That is, the first portion may be provided on any member as long as it is disposed on one side in the axial direction of the heating roller. The second portion may be provided on any member as long as it is disposed on the other side in the axial direction of the heating roller.

  Specifically, for example, as shown in FIG. 7, the first heat insulating member 81 provided between the first bearing B <b> 1 and the heating roller 41 has a first portion 81 </ b> A, and the second bearing B <b> 2 and the heating roller 41. The 2nd heat insulation member 82 provided between may have the 2nd portion 82A.

  The first heat insulating member 81 and the second heat insulating member 82 are substantially cylindrical members, and are configured with members having higher heat insulating properties than the heating roller 41. The first heat insulating member 81 is fitted to the outer peripheral surface of the heating roller 41 and is fitted to the inner race B12 of the first bearing B1. The strength of fitting the first heat insulating member 81 with the heating roller 41 is greater than the strength of fitting with the inner race B12.

  The second heat insulating member 82 is fitted to the outer peripheral surface of the heating roller 41 and is fitted to the inner race B22 of the second bearing B2. The strength of fitting the second heat insulating member 82 with the heating roller 41 is greater than the strength of fitting with the inner race B22. Thereby, the 2nd heat insulation member 82 moves with respect to the inner race B22 with the site | part of the heating roller 41 which moves to the left-right direction by thermal expansion.

  The first heat insulating member 81 includes a first portion 81A that contacts the inner race B12 of the first bearing B1, and a first flange portion 81B provided on the left side of the first portion 81A. The first flange portion 81B protrudes radially outward from the first portion 81A and is in contact with the left side surface of the inner race B12. The first portion 81A has a first intermittent contact region 61 and continuous contact portions 62 and 63 similar to those in the above embodiment.

  The second heat insulating member 82 includes a second portion 82A that comes into contact with the inner race B22 of the second bearing B2, and a second flange portion 82B that is provided on the right side of the second portion 82A. The second flange portion 82B protrudes radially outward from the second portion 82A and is in contact with the right side surface of the inner race B22. And the 2nd part 82A has the 2nd intermittent contact area | region 71 and the continuous contact parts 72 and 73 similar to the said embodiment.

  Also in this embodiment, the distance (L5) from the second intermittent contact region 71 to the right edge E2 of the second bearing B2 is the distance from the first intermittent contact region 61 to the right edge E1 of the first bearing B1 ( Since it is larger than L2), the same effect as the above embodiment can be obtained.

  In the said embodiment, although the dimension of the left-right direction of each bearing B1, B2 was made into the same dimension, this invention is not limited to this. For example, as shown to Fig.8 (a), you may make the dimension of the left-right direction of 2nd bearing B2 larger than the dimension of the left-right direction of 1st bearing B1. Further, for example, as shown in FIG. 8B, the horizontal dimension of the first bearing B1 may be larger than the horizontal dimension of the second bearing B2. In either case, the distance (L5) from the second intermittent contact area 71 to the right edge E2 of the second bearing B2 is the distance from the first intermittent contact area 61 to the right edge E1 of the first bearing B1. By making it larger than the distance (L2), it is possible to obtain the same effect as in the above embodiment.

  In the said embodiment, although the heat insulation layer 412 was provided in a part of outer peripheral surface of the raw tube 411, this invention is not limited to this, For example, you may provide a heat insulating layer in the whole outer peripheral surface of a raw tube, The heat insulating layer may not be provided on the entire outer peripheral surface of the raw tube.

  In the above embodiment, the concave portions constituting the intermittent contact regions 61 and 71 are the spiral grooves 61A and 71A, but the present invention is not limited to this. For example, the concave portion may be a plurality of spherical concave portions, or may be a plurality of annular grooves along the outer peripheral surface of the heating roller, and these annular grooves are arranged in the circumferential direction of the heating roller. It may be parallel. In the above embodiment, the intermittent contact region has a plurality of recesses arranged at intervals in the axial direction in a cross-sectional view of the heating roller cut along a plane passing through the axial line. However, the present invention is not limited to this. Instead, in the cross-sectional view, the intermittent contact region may have one recess. In this case, since the opening edge of the concave portion is a portion that intermittently contacts the bearing, the intermittent contact region is a region from the opening edge on one side in the axial direction of the concave portion to the opening edge on the other side.

  In the embodiment, the bearings B1 and B2 are ball bearings. However, the present invention is not limited to this, and the bearing may be, for example, a roller bearing or a cylindrical sliding bearing.

  In the embodiment, the halogen lamp 43 is adopted as an example of the heat source. However, the present invention is not limited to this, and may be a carbon heater, for example. Further, the heat source may heat the heating roller from the outside. The heat source may be an induction heating type IH coil.

  In the embodiment, the gear G1, the washer W, and the engagement ring R are exemplified as the restricting portions that restrict the movement of the first portion 41A in the left-right direction with respect to the first bearing B1, but the present invention is not limited to this. The structure of the restricting portion that restricts the movement of the first portion in the axial direction may be any structure. For example, instead of the gear, a ring member interposed between the gear and the bearing may be used, or instead of the washer, a part of the base tube of the heating roller may be protruded by pressing or the like. Good.

  The relationship between the areas of the first contact surface and the second contact surface is not limited to the relationship in the embodiment. For example, the area of the first contact surface and the area of the second contact surface may be the same, or the area of the first contact surface may be larger than the area of the second contact surface.

  The distribution of the amount of heat output from the heat source is not limited to the distribution as in the embodiment, and may be any distribution. The position of the temperature detector is not limited to the position as in the above embodiment, and may be any position.

  In the above embodiment, the present invention is applied to the laser printer 1. However, the present invention is not limited to this, and the present invention may be applied to other image forming apparatuses such as a copying machine and a multifunction machine. The image forming apparatus may be a printer using an LED head as an exposure apparatus, for example.

  You may implement combining each element demonstrated by embodiment mentioned above and the modification arbitrarily.

18 Fixing Device 41 Heating Roller 41A First Part 41B Second Part 43 Halogen Lamp 61 First Intermittent Contact Area 71 Second Intermittent Contact Area B1 First Bearing B2 Second Bearing E1 Edge E2 Edge

Claims (9)

A heat source,
A heating roller heated by the heat source;
A first bearing and a second bearing that rotatably support the heating roller,
The first bearing contacts a first portion located on one side of the heating roller in the axial direction;
The second bearing contacts a second portion located on the other side of the heating roller in the axial direction;
The first portion has a first intermittent contact region that is restricted from moving in the axial direction with respect to the first bearing and intermittently contacts the first bearing;
The second portion has a second intermittent contact region that intermittently contacts the second bearing;
The distance from the second intermittent contact region to the other edge in the axial direction of the second bearing is the distance from the first intermittent contact region to the other edge in the axial direction of the first bearing. Larger than the fixing device.   The area of the first contact surface in contact with the first bearing in the first portion is smaller than the area of the second contact surface in contact with the second bearing in the second portion. The fixing device according to 1.   3. The fixing device according to claim 2, wherein, of the amount of heat output from the heat source, the amount of heat on one side in the axial direction is lower than the amount of heat on the other side. A temperature detector for detecting the temperature of the heating roller;
The fixing device according to claim 3, wherein the temperature detector is located on the other side of the heating roller. The heating roller has a metal base tube,
5. The fixing device according to claim 1, wherein the first portion and the second portion have at least a part of the raw tube. 6. At least a part of the outer peripheral surface of the element pipe is provided with a heat insulating layer having higher heat insulation than the element pipe,
The fixing device according to claim 5, wherein at least one of the first portion and the second portion includes the heat insulating layer.   The fixing device according to claim 6, wherein the first portion does not include the heat insulating layer, and the second portion includes the heat insulating layer.   The fixing device according to claim 1, wherein the first intermittent contact region and the second intermittent contact region have a groove along a circumferential direction of the heating roller. A heat source,
A heating roller heated by the heat source;
A first bearing and a second bearing that rotatably support the heating roller,
The heating roller has a metal base tube,
The raw tube has a first portion that contacts the first bearing, and a second portion that contacts the second bearing,
The first portion has a first intermittent contact region that intermittently contacts the first bearing;
The fixing device according to claim 1, wherein the second portion has a second intermittent contact region that intermittently contacts the second bearing.

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