JP2018028584A - Carrier device, fixation device and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce generation of noise in a case of transferring from a nipping release state to a nipping state, compared to a case where braking is not applied to a shaft of a cam member, in a device configured to carry paper.SOLUTION: A carrier device includes: a first rotor rotating around its own axis; a second rotor rotating in contact with the first rotor; a carrying unit configured to hold and carry medium; a cam member configured to move a support part of the second rotor by rotationally driving a shaft provided in the own axis, to separate and contact the second rotor from/with the first rotor; and braking means of braking the shaft while the second rotor contacts with the first rotor with rotation of the cam member.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a conveyance device, a fixing device, and an image forming apparatus.

  As shown in FIG. 2, Patent Document 1 discloses a pressurizing mechanism 50 that pressurizes a pressurizing member 30 against a member to be pressed 40, including pressurizing members 51 and 51 d and the pressurizing member. First members 52 and 52d that pressurize the pressing member against the member to be pressed by the generated pressing force, and second members 55 and 55d that act to change the pressing force to the first member. And rotatable cams 58 and 58d disposed between the first member and the second member. The cam includes a plurality of outer peripheral portions P1 and P4 that cancel the rotational forces of the cams by the applied pressure when the cams are brought into contact with the first member and the second member by rotation of the cams. It is described that it is provided.

Japanese Patent Laying-Open No. 2015-87701

  SUMMARY OF THE INVENTION An object of the present invention is to reduce the occurrence of abnormal noise when shifting from a nip release state to a nip state in an apparatus for transporting paper, as compared with a case where the shaft of a cam member is not braked.

  The conveyance device according to claim 1 includes a conveyance unit that conveys a medium between a first rotation body that rotates around its own axis and a second rotation body that rotates in contact with the first rotation body, and the self-axis. A cam member configured to move a support portion of the second rotating body by rotating a shaft provided in a direction to move the second rotating body away from and approach the first rotating body; Braking means for braking the shaft while the second rotating body approaches the first rotating body as the member rotates.

  The conveying device according to claim 2, wherein the braking means includes a notch gear that rotates in synchronization with the shaft, and a suppression device that is connected to a gear and suppresses the rotational force of the shaft. As the cam member rotates, the second rotating body meshes with the gear while approaching the first rotating body.

  In the transport device according to claim 3, the cam member has a first surface where the distance increases at a position where the distance from the center of the shaft is the minimum when viewed from a predetermined rotation direction, and the distance is the maximum. A second surface that reduces the distance at a certain position, and a third surface that has a radial protrusion of the shaft on the side where the distance is minimum with respect to the first surface; Another cam member having a second surface, wherein the other cam member is provided in proximity to the braking means, and the braking means is adapted to rotate the cam member and the other cam member. Accordingly, while the second rotating body is approaching the first rotating body, and only the other cam member is separated from the first rotating body by the third surface. During this time, the shaft is braked.

  The conveying device according to claim 4, wherein the braking means includes a notch gear that rotates in synchronization with the shaft, and a suppression device that is connected to the gear and suppresses the rotational force of the shaft, and the notch gear includes the As the cam member and the other cam member rotate, the second rotating body approaches the first rotating body and only the other cam member rotates the second rotation by the third surface. While the body is separated from the first rotating body, the body meshes with the gear.

  6. The transport device according to claim 5, wherein the support portion includes an operation portion that contacts an outer peripheral surface of the cam member, and the cutout gear meshes with the gear when at least the outer peripheral surface and the operation portion do not contact each other. .

  A fixing device according to a sixth aspect includes the conveying device according to any one of the first to fifth aspects, wherein one of the first rotating body and the second rotating body is a heating body, and the other is the other. It is formed as a pressurized body.

  An image forming apparatus according to a seventh aspect includes the image forming unit and the fixing device according to the sixth aspect.

  9. The image forming apparatus according to claim 8, wherein the image forming apparatus is disposed so as to be able to contact with and separate from a driving unit that drives the shaft and a transmission gear connected to the shaft, and transmits power from the driving unit to the shaft. The movable gear is joined to the transmission gear when power is transmitted from the drive means to the shaft, and the power is transmitted when power is transmitted from the shaft to the drive means. Separate from the gears.

  According to the first aspect of the present invention, it is possible to provide a transport device that reduces the occurrence of abnormal noise when shifting from the nip release state to the nip state, as compared with the case where braking is not applied to the shaft of the cam member.

  According to invention of Claim 2, compared with the case where notched gear is not used, the time of cancellation | release of a nip state and the braking start by a suppression apparatus can be arrange | equalized.

  According to the invention of claim 3, it is possible to provide a transport device that reduces the occurrence of abnormal noise as compared with the case where the nip state is simultaneously released by two cam members.

  According to the fourth aspect of the present invention, it is possible to provide a transport device that reduces noise as compared with a case where a notched gear is used and the nip state is simultaneously released by two cam members.

  According to the fifth aspect of the present invention, it is possible to provide a conveying device that reduces noise compared to the case where the outer peripheral surface of the cam member does not contact the operating portion and the notch gear does not mesh with the gear.

  According to the sixth aspect of the present invention, it is possible to provide a fixing device that reduces the occurrence of abnormal noise when shifting from the nip release state to the nip state, compared to a case where braking is not applied to the shaft of the cam member.

  According to the seventh aspect of the present invention, it is possible to provide an image forming apparatus that can reduce the occurrence of abnormal noise when shifting from the nip release state to the nip state, compared to a case where braking is not applied to the shaft of the cam member. .

  According to the eighth aspect of the present invention, it is possible to provide an image forming apparatus that reduces abnormal noise compared to the case where no moving gear is used.

1 is a configuration diagram illustrating an image forming apparatus according to a first embodiment. 1 is an external perspective view of a fixing device according to a first embodiment. 1 is a side cross-sectional view illustrating a fixing device and a driving device according to a first embodiment. It is a side view of the common cam which concerns on 1st Embodiment. FIG. 3 is an explanatory diagram illustrating a nip state in the fixing device according to the first embodiment. FIG. 6 is an enlarged view of the cam and the braking device of FIG. 5. FIG. 4 is an explanatory diagram illustrating a nip release state in the fixing device according to the first embodiment. It is an enlarged view of the cam and braking device of FIG. (A) The side view of a 1st cam which concerns on 2nd Embodiment, (B) The side view of a 2nd cam. It is explanatory drawing of the effect | action by the 1st cam which concerns on 2nd Embodiment. It is explanatory drawing of the effect | action by the 2nd cam which concerns on 2nd Embodiment.

(First embodiment)
An example of a conveyance device, a fixing device, and an image forming apparatus according to the first embodiment will be described.

〔overall structure〕
FIG. 1 shows an image forming apparatus 10 of the present embodiment. In the following description, the direction indicated by the arrow Y in FIG. 1 is the apparatus height direction, and the direction indicated by the arrow X is the apparatus width direction. In addition, a direction (indicated by Z) orthogonal to each of the apparatus height direction and the apparatus width direction is defined as an apparatus depth direction. Then, when the image forming apparatus 10 is viewed from the front, the apparatus height direction, the apparatus width direction, and the apparatus depth direction are described as a Y direction, an X direction, and a Z direction. Further, when it is necessary to distinguish one side and the other side in the X direction, the Y direction, and the Z direction, when the image forming apparatus 10 is viewed from the front, the upper side is the Y side, the lower side is the -Y side, and the right side is X side, left side is described as -X side, rear side is described as Z side, and front side is described as -Z side.

  As an example, the image forming apparatus 10 includes a transport unit 12 including a roll pair 13 that transports the paper P, and an image forming unit 14 that forms a toner image G using toner T on the paper P transported by the transport unit 12. And a fixing device 30 that heats and pressurizes the toner image G and fixes the toner image G on the paper P. A line indicated by a symbol K shown in FIG. The paper P is an example of a medium (recording medium).

  The image forming unit 14 includes an image forming unit 20 and a control unit 22 that controls the operation of each unit of the image forming unit 20 to form a toner image G on the paper P. For example, the image forming unit 20 is configured to perform each process of charging, exposure, development, and transfer, which are known electrophotographic methods.

[Main part configuration]
Next, the fixing device 30 will be described with reference to FIGS. 2 is an external perspective view of the fixing device 30, and FIG. 3 is a cross-sectional view of the fixing device 30 in the vicinity of the center in the Z direction, and is a side sectional view of the −Z direction observed from the Z direction.

  The fixing device 30 functions as a conveying device that conveys the paper P with a fixing roll 32 rotating around its own axis and a pressure belt 34 rotating in contact with the fixing roll 32. 2 and 3, the fixing device 30 includes a fixing roll 32, a pressure belt 34, a halogen heater 36, a bracket 38, a lever member 42, a tension spring 44, a cam follower 46, A common cam 50 and a braking device 60 are provided. In the fixing device 30 of the present embodiment, the bracket 38, the lever member 42, the tension spring 44, the cam follower 46, and the common cam 50 are formed one by one on both sides in the Z direction of the fixing device 30. The fixing roll 32 is an example of a first rotating body. The pressure belt 34 is an example of a second rotating body. The lever member 42 is an example of a support part. The common cam 50 is an example of a cam member. The braking device 60 is an example of a braking unit.

  The fixing roll 32, the pressure belt 34, the halogen heater 36, the bracket 38, the lever member 42, the tension spring 44, the cam follower 46, and the common cam 50 are a rectangular parallelepiped housing 31 (FIG. 1) that is a main body portion of the fixing device 30. See).

  Both ends of a cylindrical shaft 35 whose axial direction is the Z direction are fixed to the housing 31 by a bearing (not shown). The shaft 35 is rotationally driven by a motor 71 (see FIG. 2) controlled by the control unit 22 (see FIG. 1). A rotation driving method by the motor 71 will be described later.

<Fixing roll>
For example, the fixing roll 32 is configured such that an elastic body layer made of silicon rubber and a release layer made of fluororesin are formed on the outer peripheral surface of a cylindrical cored bar made of aluminum. A halogen heater 36 as a heating source is provided inside the core of the fixing roll 32. Further, the fixing roll 32 is disposed on the toner image G side (−X side) with respect to the conveyance path K (see FIG. 1) of the paper P. Further, the fixing roll 32 is rotatable around the axis with the Z direction as an axial direction. A gear (not shown) is provided on the Z side of the shaft portion of the fixing roll 32. This gear is rotated by a motor (not shown). In this way, the fixing roll 32 is heated by the halogen heater 36 and heats and pressurizes the paper P while rotating together with a pressure belt 34 described later, whereby the toner image G (toner T) on the paper P shown in FIG. ) Is fixed on the paper P. That is, in the present embodiment, the fixing roll 32 is formed as an example of a heating body.

(Halogen heater)
The halogen heater 36 shown in FIG. 2 generates heat when energized from a power source (not shown), and heats the entire fixing roll 32 by heating the cored bar. Whether the halogen heater 36 is energized is determined based on a detection result of a temperature sensor (not shown) that detects the temperature of the outer peripheral surface of the fixing roll 32.

<Pressure belt>
As an example, the pressure belt 34 is an endless belt having a polyimide base layer and a fluororesin release layer laminated on the base layer. The pressure belt 34 is disposed on the opposite side (X side) to the toner image G side with respect to the conveyance path K (see FIG. 1) of the paper P. The pressure belt 34 is disposed so as to be rotatable around the axis with the Z direction as the axial direction. Specifically, a pad (not shown) supported by a lever member 42 described later contacts the inner peripheral surface of the pressure belt 34 and presses (presses) the pressure belt 34 against the outer peripheral surface of the fixing roll 32. The pressure belt 34 rotates in synchronism with the rotation of the fixing roll 32. That is, in the present embodiment, the pressure belt 34 is formed as an example of a pressure body. The pressure belt 34 is disposed on the X side with respect to the fixing roll 32.

  As shown in FIG. 3, the outer peripheral surface of the fixing roll 32 and the outer peripheral surface of the pressure belt 34 sandwich the paper P, and a portion where the toner T on the paper P is heated and pressed is defined as a nip portion N. Called. That is, the pressure belt 34 forms a nip portion N with the fixing roll 32 sandwiching the paper P. When there is no paper P, the fixing roll 32 and the pressure belt 34 are in contact with each other at the nip portion N. In this embodiment, as an example, the conveyance direction of the paper P in the fixing device 30 is a direction from the lower side (−Y side) to the diagonally upper side (−X side and Y side). It is arranged along the diagonal direction.

<Bracket>
A pair of brackets 38 are provided in the casing 31 (see FIG. 1), and face each other in the Z direction with the fixing roll 32 therebetween. The bracket 38 has the same configuration on the Z side and the −Z side of the fixing roll 32 and is disposed symmetrically with respect to the center of the fixing roll 32 in the Z direction.

  The bracket 38 is configured by a plate-like member that is disposed along the XY plane and has a Z direction as a thickness direction. A bearing (not shown) is attached to the bracket 38. A core metal of the fixing roll 32 is inserted into this bearing. That is, the bracket 38 supports the fixing roll 32.

  Further, both ends of the shaft 43 with the Z direction as the axial direction are fixed to the X side of the support portion of the fixing roll 32 of the bracket 38 by screws (not shown). A through hole 39 penetrating in the Z direction is formed at a position on the −X side of the support portion of the fixing roll 32 of the bracket 38. A lower end of a tension spring 44 described later is fixed to the through hole 39.

<Lever member>
A pair of lever members 42 are provided in the casing 31 (see FIG. 1), and face each other in the Z direction with the fixing roll 32 therebetween. The lever member 42 has the same configuration on the Z side and the −Z side of the fixing roll 32 and is arranged symmetrically with respect to the center of the fixing roll 32 in the Z direction.

  The lever member 42 is a plate-like member that is disposed along the XY plane and has a thickness direction in the Z direction. Further, the lever member 42 linearly extends from the lower side (−Y side) to the upper side (Y side) of the housing 31, and then gently arcs in the −X direction, and then linearly extends to the −X side. It extends to. A bearing (not shown) is attached to the lower end (−Y side end) of the lever member 42. A shaft 43 is inserted into this bearing. Thereby, the lever member 42 is supported so as to be rotatable around the axis of the shaft 43. In other words, the lever member 42 is rotatably supported by the bracket 38.

  Here, the pad (not shown) is in contact with the inner peripheral surface of the pressure belt 34 as described above. On the other hand, the lever member 42 supports both ends of the pad in the Z direction. Since the pad supports the pressure belt 34 so as to be movable in the circumferential direction, the lever member 42 supports the pressure belt 34.

A cam follower 46, which will be described later, is fixed to the linear portion at the top of the lever member 42. The cam follower 46 is formed at the lower end of the straight portion of the lever member 42. A common cam 50 is provided below the cam follower 46. That is, the straight portion of the lever member 42 is located above (Y side) the shaft 35 that supports the common cam 50.
A through hole 45 is formed at the base of the straight portion above the lever member 42. An upper end of a tension spring 44 described later is fixed to the through hole 45.

<Cam follower>
As an example, the cam follower 46 is configured by a member having a U-shaped cross section perpendicular to the longitudinal direction of the linear portion above the lever member 42. The cam follower 46 is provided on the lever member 42 by being stacked on the lower side (−Y side) of the straight portion of the lever member 42 in the X direction and fixed with a screw (not shown). Thus, the cam follower 46 constitutes a part of the lever member 42. In addition, the contact surface which contacts the outer peripheral surface of the common cam 50 mentioned later of the cam follower 46 is made into a plane.

<Tension spring>
The tension spring 44 is hooked into a through hole 45 formed in the lever member 42 at the upper end and hooked into a through hole 39 formed in the bracket 38 to connect the lever member 42 and the bracket 38. It is arranged to be elastically deformable in the direction. The tension spring 44 is provided for each lever member 42. The tension spring 44 presses the nip portion N formed by the fixing roll 32 and the pressure belt 34 in the rotation direction around the shaft 43. Further, the tension spring 44 applies an elastic force to the common cam 50 in a nip release state described later, and applies an elastic force to the nip portion N in a nip state described later.

<Cam member>
As shown in FIG. 2, the common cam 50 contacts the cam follower 46 and rotates to move the lever member 42 and move the lever member 42 relative to the bracket 38. In other words, the pressure belt 34 is separated from and approaches the fixing roll 32. The common cam 50 is disposed with the Z direction as the rotation axis direction. The common cam 50 is provided so that the crests of the lever members 42 face the same direction. Here, the common cam 50 is an example of a cam member.

As shown in FIG. 4, the common cam 50 is a component whose outer peripheral surface is a curved surface and whose Z direction is the thickness direction (see FIG. 2). Further, the common cam 50 is formed with a circular through hole 53 penetrating in the Z direction. The aforementioned shaft 35 (see FIGS. 2 and 3) is press-fitted into the through-hole 53 and fixed. Assuming that the center position when the through hole 53 is viewed in the Z direction is O, the common cam 50 has a maximum point H having the longest distance from the center position O to the outer peripheral surface, and a distance from the center position O to the outer peripheral surface. It has the shortest lowest point L. Here, the center position O is the rotation center position of the common cam 50.
The highest point H corresponds to the “position where the distance from the center of the axis is the maximum” in the present invention. The lowest point L corresponds to the “position where the distance from the center of the axis is minimum” in the present invention.

  When the common cam 50 is observed from the downstream side to the upstream side in the rotation direction (arrow R direction), the outer peripheral surface from the lowest point L to the highest point H is referred to as the rising surface 55, and the highest point H To the lowest point L is referred to as a descending surface 56. The vicinity of the highest point H is a surface having a constant distance from the center position O to the outer peripheral surface, and this surface is referred to as an arc surface P1. Further, a part of the rising surface 55 has a surface that stops in a state where the cam follower 46 is in contact with the thick paper P such as an envelope, and this surface is referred to as an intermediate surface P2.

In the following description, the rotation position of the common cam 50 is specified as follows.
(1) When the common cam 50 is not in contact with the cam follower 46 It is specified by the position of the upper end portion (Y side end portion) of the outer peripheral surface of the common cam 50.
(2) When the common cam 50 is in contact with the cam follower 46 It is specified by the contact position of the outer peripheral surface of the common cam 50 with the cam follower 46.

  As shown in FIG. 3, when the common cam 50 rotates clockwise and the ascending surface 55 rotates while contacting the cam follower 46, the lever member 42 rises (moves to the Y side). That is, the pressure belt 34 is separated from the fixing roll 32. On the other hand, when the descending surface 56 rotates while contacting the cam follower 46, the lever member 42 descends (moves to the -Y side). That is, the pressure belt 34 approaches the fixing roll 32. Here, “separation” and “approach” mean that the distance between the fixing point of the pressure belt 34 and the axis of the fixing roll 32 changes. Therefore, even if the pressure belt 34 is in contact with the fixing roll 32 and is pressed, it is “approach” if the distance between the two is shortened (when the pressure is increased), and the distance between the two is increased ( It is “separated” (if the applied pressure decreases). Further, the state of “separating” and “approaching” may be either a continuous change or a step change.

  The nip state occurs when the common cam 50 is located at the lowest point L and the common cam 50 is not in contact with the cam follower 46. Further, when the common cam 50 is in contact with the cam follower 46 on the circular arc surface P1, the nip is released. Further, when the common cam 50 is in contact with the cam follower 46 on the intermediate surface P2, the pressure applied at the nip portion is smaller than that in the nip state, which is suitable for forming an image on a thick paper P such as an envelope. It becomes a state.

<Braking device>
The braking device 60 brakes the shaft 35 while the lever member 42 is lowered as the common cam 50 rotates. That is, the braking device 60 brakes the rotation of the common cam 50 while the pressure belt 34 is approaching the fixing roll 32.

As shown in FIGS. 2 and 3, the braking device 60 is provided on one side (−Z side) of the pair of common cams 50, and includes a notch gear 61, an entire peripheral gear 63, and a torque limiter 64. have.
Here, the notch gear 61 is an example of a notch gear. The torque limiter 64 is an example of a suppression device.

  The notch gear 61 rotates in synchronization with the shaft 35. A circular through hole penetrating in the Z direction is formed in the notch gear 61, and the shaft 35 is fixed by being press-fitted into the through hole. The notch gear 61 is provided in the vicinity of the common cam 50 on the near side (−Z side), but since the common cam 50 is also fixed to the shaft 35 as described above, the common cam 50 and the notch gear are provided. 61 rotates together with the shaft 35.

  Here, the notch gear 61 has teeth formed only on a part of the circumferential direction of the shaft 35 (see FIG. 6). Specifically, it is partially formed along the rising surface 55 of the adjacent common cam 50. The notch gear 61 is a rotating shaft of a torque limiter 64 to be described later while the lever member 42 is lowered with the rotation of the common cam 50 and the shaft 35, that is, while the pressure belt 34 is approaching the fixing roll 32. It is formed so as to mesh with the all-around gear 63 connected to 66.

  The torque limiter 64 suppresses the rotational force of the shaft 35, in other words, gives a braking force to the shaft 35. Specifically, the torque limiter 64 generates a load torque by a spring provided therein. An all-around gear 63 is connected to the rotating shaft 66 of the torque limiter 64.

  When the notch gear 61 meshes with the entire circumference gear 63 along with the rotation of the shaft 35, a load torque is transmitted to the shaft 35. That is, the rotational force of the shaft 35 is suppressed.

<Rotation drive method of shaft>
A method for rotationally driving the shaft 35 to which the common cam 50 and the notch gear 61 are fixed will be described below. As shown in FIG. 3, a motor 71 for driving the shaft 35 is provided on the −X side from the fixing device 30, and the shaft 35 is connected to the motor 71 through a plurality of gears. Specifically, a pinion 72 is fixed to the output shaft of the motor 71. A moving gear 73 is connected to the pinion 72. The moving gear 73 is formed such that the rotation shaft can move depending on the rotation direction of the motor 71. In the present embodiment, when the motor 71 rotates in the forward direction, the moving gear 73 moves away from the transmission gear 74 toward the operating gear 76 and is joined to the operating gear 76 to drive the operating gear 76. On the other hand, when the motor 71 rotates in the reverse direction, the moving gear 73 moves away from the operating gear 76 and moves to the transmission gear 74 side and joins the transmission gear 74 to drive the transmission gear 74.

  Here, the operating gear 76 is connected to a conveying device for conveying the toner T from the container for the toner T formed in the image forming unit 20 toward the developing device. That is, when the motor 71 rotates in the forward direction, the toner T is supplied to the developing device.

  On the other hand, a plurality of transmission gears 74 are connected between the moving gear 73 and the shaft 35. When the moving gear 73 rotates the transmission gear 74, the rotation is decelerated and transmitted to the shaft 35, and the shaft 35 rotates in the direction of arrow R.

  Here, regarding the torque received by the shaft 35, a case where the driving force is received from the motor 71 is a positive torque, and a case where the driving force is received from the common cam 50 is a negative torque. The motor 71 is an example of a driving unit. The moving gear 73 is an example of a moving gear. Furthermore, the transmission gear 74 is an example of a transmission gear.

(Operational effects of the first embodiment)
Next, the effect of this embodiment is demonstrated for every state.

(1) Nip State FIGS. 5 and 6 show the fixing device 30 in the nip state. In the nip state, the common cam 50 is not in contact with the cam follower 46, and the force to lift the lever member 42 upward (Y direction) does not work. That is, since the lever member 42 is tensioned downward (−Y direction) by the tension spring 44, the pressure belt 34 is pressed against the outer peripheral surface of the fixing roll 32, and the nip portion N is pressurized. Then, the paper P on which the toner image G is formed is passed through the nip portion N in the nip state, whereby the toner image G (toner T) on the paper P is fixed to the paper P.

  In the nip state, the notch gear 61 is slightly meshed with the entire circumference gear 63. Specifically, as shown in FIG. 6, the tooth at the rear end of the rotation direction (arrow R direction) of the notch gear 61 touches the entire circumferential gear 63.

  As described above, when the common cam 50 and the cam follower 46 do not contact each other, the notch gear 61 meshes with the entire peripheral gear 63, and when the common cam 50 rotates in the direction of arrow R in FIG. The meshing between 61 and the circumferential gear 63 is disengaged.

(2) Transition from the nip state to the nip release state First, when shifting to the nip release state, the motor 71 is driven to rotate reversely under the control of the control unit 22. Then, the common cam 50 starts to rotate in the direction of arrow R, and the rising surface 55 starts to contact the cam follower 46. As the common cam 50 rotates, the lever member 42 is lifted upward (Y direction) against the tension of the tension spring 44.

  Here, an elastic force is exerted on the common cam 50 by the tension spring 44. Therefore, in the common cam 50, torque that tends to rotate in the direction in which the distance from the center position O to the outer peripheral surface is reduced, that is, in the rising surface 55, in the direction opposite to the rotation direction of the common cam 50 (arrow R direction). Occur. Therefore, the motor 71 needs to drive the shaft 35 with a positive torque that is at least larger than this torque. Note that the notch gear 61 does not mesh with the all-around gear 63, so no braking force acts on the shaft 35. For this reason, the motor 71 does not require a driving force other than rotating the common cam 50, that is, a driving force that opposes the braking force of the torque limiter 64, and the motor 71 is not overloaded.

  Here, when the rotation of the common cam 50 is stopped in a state where the intermediate surface P2 is in contact with the cam follower 46, a state suitable for forming an image on a thick paper P such as an envelope is obtained.

(3) Nip release state After the common cam 50 starts rotating, when the highest point H (arc surface P1) is in contact with the cam follower 46, in other words, when the lever member 42 is in the most lifted state, the motor 71 rotates in the reverse direction. End driving. That is, the nip is released.
7 and 8 show the fixing device 30 in the nip released state. When the lever member 42 is lifted, the pressure belt 34 is separated from the fixing roll 32, so that the pressure applied to the nip portion N is reduced or eliminated.

  In the nip release state, the notch gear 61 is slightly meshed with the all-around gear 63 or is in a meshed state. Specifically, the foremost tooth in the rotational direction of the notch gear 61 (in the direction of arrow R) is in contact with the circumferential gear 63.

(4) Transition from the nip release state to the nip state First, when shifting to the nip state, the motor 71 is driven to rotate reversely under the control of the control unit 22. Then, the common cam 50 starts to rotate in the arrow R direction, and the descending surface 56 starts to contact the cam follower 46. Further, the notch gear 61 is completely meshed with the entire circumference gear 63. As the common cam 50 rotates, the lever member 42 descends downward (−Y direction). When the lever member 42 is lowered, the pressure belt 34 approaches the fixing roll 32 and the pressure applied to the nip portion N increases.

The fixing device 30 of the present embodiment formed as described above has the following effects.
First, as described above, the elastic force by the tension spring 44 is applied to the common cam 50. Therefore, in the common cam 50, torque that tends to rotate in the same direction as the rotation direction of the common cam 50 (the direction of the arrow R) in the direction in which the distance from the center position O to the outer peripheral surface is reduced, that is, in the descending surface 56. Occur. This torque is a torque for rotating the motor 71, that is, a negative torque. Therefore, when shifting from the nip release state to the nip state, the torque received by the shaft 35 reverses from positive to negative.

  On the other hand, the notch gear 61 meshes with the entire circumference gear 63, so that a braking force acts on the shaft 35. Therefore, the negative torque that acts on the shaft 35 is relaxed.

  A driving force is transmitted from the motor 71 toward the common cam 50 via gears such as a pinion 72, a moving gear 73, and a transmission gear 74, and backlash exists in the meshing of these gears. . When the torque is reversed from positive to negative, abnormal noise is generated due to the collision of the teeth of each gear. According to this embodiment, the negative torque is relieved by providing the braking device 60. That is, since the difference between the positive torque and the negative torque is reduced with respect to the torque received by the shaft 35, the collision energy between the gear teeth can be suppressed. And the collision sound between gear teeth becomes small. That is, the generation of abnormal noise can be suppressed compared to the case where the braking device 60 is not provided.

In the present embodiment, the moving gear 73 can also suppress abnormal noise caused by the collision between gear teeth.
As described above, in the present embodiment, when the motor 71 rotates in the reverse direction, the moving gear 73 moves from the operating gear 76 side to the transmission gear 74 side to drive the transmission gear 74. That is, when the shaft 35 receives a positive torque, the moving gear 73 meshes with the transmission gear 74. When the transition from the nip release state to the nip state occurs and the torque received by the shaft 35 is reversed from positive to negative, when the moving gear 73 receives torque from the transmission gear 74, the moving gear 73 operates from the transmission gear 74 side. Move to the gear 76 side. That is, the meshing between the moving gear 73 and the transmission gear 74 is released.

  Further, when the meshing between the moving gear 73 and the transmission gear 74 is disengaged, torque is not transmitted to other gears such as the pinion 72 and the operating gear 76. That is, the gear teeth do not collide with each other on the motor 71 side from the transmission gear 74. Further, in the transmission gear 74, since the collision energy between the gear teeth is released, the collision noise that is abnormal noise is suppressed. That is, the generation of abnormal noise can be suppressed as compared with the case where the moving gear 73 is not provided.

(Second Embodiment)
In the first embodiment, the fixing device 30 is formed by a pair of common cams 50 having the same shape. In the second embodiment, the fixing device 30 is fixed by cams having different shapes (a first cam 51 and a second cam 52). A device 30 is formed.
In the following description, differences from the first embodiment will be described.

<Cam member>
The fixing device 30 of the present embodiment includes a first cam 51 that is close to the notch gear 61 and a second cam 52 that is on the opposite side of the first cam 51 in the Z direction. FIG. 9A shows the first cam 51 and FIG. 9B shows the second cam 52. In the present embodiment, the second cam 52 is an example of a cam member. Also. The first cam 51 is an example of another cam member.
The first cam 51 has the same shape as the common cam 50.

  On the other hand, the second cam 52 is partly different from the first cam 51 in shape. Specifically, as shown in FIG. 9B, a circular through-hole 53 that penetrates in the Z direction is formed as in the first cam 51, and the shaft 35 is press-fitted into the through-hole 53. It is fixed. Assuming that the center position when the through hole 53 is viewed in the Z direction is O, the second cam 52 has the highest point H and the lowest point L at the same position as the first cam 51. The distance from the center position O to the outer peripheral surface at the highest point H of the second cam 52 is the same as the distance of the first cam 51. Further, the distance from the center position O to the outer peripheral surface at the lowest point L of the second cam 52 is the same as the distance of the first cam 51.

  When the second cam 52 is observed from the downstream side to the upstream side in the rotation direction (arrow R direction), the outer peripheral surface from the highest point H to the lowest point L of the second cam 52 is the first. It is formed as the same descending surface 56 as the cam 51. The shape of the circular arc surface P <b> 1 of the second cam 52 is the same as that of the first cam 51.

  On the other hand, when the second cam 52 is observed from the downstream side to the upstream side in the rotation direction (arrow R direction), the outer peripheral surface from the lowest point L to the highest point H of the second cam 52 is the first. One cam 51 is formed as a rising surface 54 that is partly different in shape. Specifically, the shape of the outer peripheral surface from the lowest point L of the second cam 52 to the intermediate surface P2 is shorter than the first cam 51 from the center position O to the outer peripheral surface. Is formed low. In addition, the shape of the outer peripheral surface from the intermediate surface P2 of the second cam 52 and the intermediate surface P2 to the highest point H is the same as that of the first cam 51.

  As described above, when the differences in the shapes of the first cam 51 and the second cam 52 are summarized, there is a difference in the shape of the outer peripheral surface on the rising surfaces (54, 55). Here, when the different portion on the first cam 51 side is called a first different surface P3 and the different portion on the second cam 52 side is called a second different surface P4, in FIG. The shape is as indicated by the dotted line, and it can be said that the first different surface P3 protrudes from the second different surface P4.

  That is, when the first cam 51 is observed with reference to the second cam 52, the first cam 51 has a rising surface 55 having a radial protrusion of the shaft 35 on the lowest point L side of the rising surface 54 of the second cam 52. And a lowering surface 56 having the same shape as the second cam 52. In the second embodiment, the rising surface 54 is an example of the first surface. The descending surface 56 is an example of a second surface. Furthermore, the rising surface 55 is an example of a third surface.

<Braking device>
In the braking device 60 of the second embodiment, the shape of the notch gear 61 is different from that of the first embodiment. Specifically, the notch gear 61 of the second embodiment is similar to the notch gear 61 of the first embodiment in that teeth are partially formed along the rising surface 55 of the adjacent first cam 51. It is. In the notch gear 61 of the second embodiment, the position where the foremost tooth in the rotational direction (arrow R direction) is formed is the same as that of the first embodiment. On the other hand, in the notch gear 61 of the second embodiment, the position where the rearmost tooth in the rotational direction (arrow R direction) is formed is located further rearward than in the first embodiment. That is, when compared with the notch gear 61 of the first embodiment, the notch gear 61 of the second embodiment is configured such that the cam follower 46 contacts the rising surface 55 (first different surface P3) and slightly rotates. It is formed so that the mesh with the all-around gear 63 is disengaged.

  In the second embodiment, the notch gear 61 is moved while the lever member 42 is lowered with the rotation of the first cam 51 and the shaft 35, that is, while the pressure belt 34 is approaching the fixing roll 32. It forms so that it may mesh with the all-around gear 63 connected to the rotating shaft of the torque limiter 64 mentioned later.

  On the other hand, the notch gear 61 is formed so that the engagement with the circumferential gear 63 is released after the lever member 42 is slightly lifted with the rotation of the first cam 51 and the shaft 35. Specifically, the notch gear 61 is formed so as to be disengaged from the entire peripheral gear 63 between the time when the first cam 51 contacts the cam follower 46 and the time when the second cam 52 contacts the cam follower 46. In other words, while only the first cam 51 causes the pressure belt 34 to be separated from the fixing roll 32 by the rising surface 55, the notch gear 61 meshes with the entire peripheral gear 63.

(Operational effects of the second embodiment)
The operation and effect when the first cam 51 and the second cam 52 formed as described above are shifted from the nip state to the nip release state are as follows.

  That is, the present embodiment is characterized in that the timing of lifting the lever member 42 by the first cam 51 and the second cam 52 is different.

  First, when shifting to the nip release state, the motor 71 is reversely driven by the control of the control unit 22. Then, the first cam 51 and the second cam 52 start to rotate in the direction of arrow R, and first, the rising surface 55 of the first cam 51 starts to contact the cam follower 46. At this time, the rising surface 54 of the second cam 52 is not yet in contact with the cam follower 46.

  Furthermore, the state which rotated the 1st cam 51 and the 2nd cam 52 to the arrow R direction is shown in FIG.10 and FIG.11. Here, FIG.10 and FIG.11 has shown the state of the cam in the same rotational position. As shown in FIG. 10, in the first cam 51, the lever member 42 is lifted on the first different surface P <b> 3 (see FIG. 9A) of the rising surface 55. On the other hand, as shown in FIG. 11, in the second cam 52, the second different surface P <b> 4 (see FIG. 9B) of the rising surface 54 starts to contact the cam follower 46.

  Here, in the second embodiment, as described above, while only the first cam 51 separates the pressure belt 34 from the fixing roll 32 by the ascending surface 55, the notch gear 61 and the circumferential gear 63. It is formed to mesh.

According to 2nd Embodiment, there exist the following effects.
First, as in the case of the notch gear 61 of the first embodiment, when the meshing of the notch gear 61 with the entire peripheral gear 63 is disengaged with the transition from the nip state to the nip released state, the following two problems have occurred.

First, the first problem is as follows.
When the notch gear 61 and the circumferential gear 63 are engaged with each other, strain energy is accumulated in the notched gear 61 and the circumferential gear 63 due to the elastic force of the tension spring 44 received by the first cam 51 and the braking force of the torque limiter 64. Has been. Here, when the lowering of the lever member 42 is finished and the meshing of the notch gear 61 with the entire circumferential gear 63 is released, the strain energy accumulated in the notched gear 61 and the entire circumferential gear 63 is instantaneously released. Here, a backlash exists in the meshing of the notch gear 61 and the circumferential gear 63. When the strain energy accumulated in the notch gear 61 and the entire peripheral gear 63 is released instantaneously, the entire peripheral gear 63 rotates reversely due to the reaction, and the teeth of the notch gear 61 and the peripheral peripheral gear 63 are geared together. Collide, and abnormal noise is generated.

The second problem is as follows.
As described above, when the notch gear 61 and the entire circumference gear 63 are engaged with each other and strain energy is accumulated, the bearing 35 that supports the shaft 35 and the deflection of the shaft 35 cause the shaft 35 that is the axis of the notch gear 61 to The rotary shaft 66 of the torque limiter 64, which is the axis of the circumferential gear 63, is separated. That is, the distance between the shafts is widened by trying to escape the shafts of the notch gear 61 and the entire peripheral gear 63. When the notch gear 61 and the entire circumference gear 63 are disengaged and the strain energy is released instantaneously, the distance between the axes returns instantaneously, so that the shaft 35, the axis of the torque limiter 64, etc. A collision noise is generated from the bearing that supports the bearing and the bracket 38 that holds the bearing. That is, abnormal noise is generated.

  With respect to the above problems, the second embodiment is formed so that the meshing of the notch gear 61 with the entire peripheral gear 63 is released while only the first cam 51 lifts the lever member 42. That is, the notch gear 61 and the entire peripheral gear 63 are disengaged in a state where less strain energy is accumulated than when both the lever members 42 are lifted by the first cam 51 and the second cam 52. Therefore, by reducing the amount of strain energy that is released when the notch gear 61 and the circumferential gear 63 are disengaged, the reaction between the gears is suppressed, the collision of the gear teeth is suppressed, and the noise is suppressed. .

  Further, by reducing the amount of strain energy released when the notch gear 61 and the entire peripheral gear 63 are disengaged, the amount of change in the inter-axis distance between the notch gear 61 and the entire peripheral gear 63 can be suppressed. It is possible to suppress the occurrence of a collision sound when the mesh is disengaged.

  According to the second embodiment, since the braking force of the torque limiter 64 is released before the second cam 52 lifts the lever member 42, the increase in driving force required by the motor 71 can be suppressed. . That is, the overload of the motor 71 can be minimized.

(Supplement)
As described above, the present invention has been described in detail with respect to specific embodiments. However, the present invention is not limited to the above-described embodiments, and other embodiments are possible within the scope of the technical idea of the present invention. It is.

For example, in each embodiment, an example of the present disclosure has been described as the fixing device 30. However, the present invention may be used as a transport device that transports the paper P in addition to the fixing device 30 as long as the device transports the paper P. For example, a part of the transfer unit in the image forming apparatus 10 may be used as a transfer device of the present invention, and may be used as a transfer device that also has a function of transferring paper P. In addition to the electrophotographic image forming apparatus 10, the apparatus may be used for an apparatus that conveys a sheet material.
The present invention is not limited to the configuration in which the nip portion N is formed by the fixing roll 32 and the pressure belt 34 by the rotation around the shaft 43 as in the fixing device 30 of each embodiment. The nip portion N may be formed by horizontally moving the pressure belt 34.

  In each embodiment, the bracket 38 supports the fixing roll 32 and the lever member 42 supports the pressure belt 34. However, as long as one of them is rotatable with respect to the other, the bracket 38 may support the pressure belt 34 and the lever member 42 may support the fixing roll 32.

  In each embodiment, the fixing roll 32, which is an example of a heating body, is used as a first rotating body, and the pressure belt 34, which is an example of a pressing body, is used as a second rotating body. The 32 side may be configured as a second rotating body, and the pressure belt 34 side may be configured as a first rotating body. In each embodiment, the pressure belt 34 has been described as an example of a pressure body. However, an example of the pressure member is not limited to the pressure belt 34 as long as it has a function of pressing the toner on the paper P. For example, instead of the pressure belt 34, a configuration like the fixing roll 32, in other words, a cylindrical pressure roll may be used.

  Moreover, in the braking device 60 of each embodiment, the shaft 35 was braked using the torque limiter 64, but the braking method is not limited to this. For example, a method of braking the shaft 35 by directly pressing a rubber material against the shaft 35 or a method of braking the shaft 35 using a viscous resistance of a fluid like a fluid coupling may be employed.

  In the braking device 60 of each embodiment, the notch gear 61 is meshed with the entire circumference gear 63 and the braking force is applied to the shaft 35 while the pressure belt 34 approaches the fixing roll 32. It is not always necessary to brake while approaching. If abnormal noise is suppressed, it is sufficient to apply braking at any timing while the pressure belt 34 approaches the fixing roll 32.

  In each embodiment, the fixing device 30 is described as constituting the image forming apparatus 10. Further, the fixing device 30 has been described as fixing the toner image on the paper P formed by the image forming unit 14. However, if the fixing device 30 fixes an image on the paper P, the image formed on the paper P by the image forming unit may not be a toner image. For example, the fixing device 30 may be used for fixing an image formed on the paper P by ejecting droplets onto the paper P by a droplet ejection device. In this case, the image forming unit is an ink jet type image forming unit, and the image forming apparatus is an ink jet type image forming apparatus. Further, the image forming unit may be an image forming unit of a so-called offset printing apparatus, and the fixing device 30 may be used for fixing an image formed by the image forming unit. In this case, the image forming unit is an offset type image forming unit, and the image forming apparatus is an offset type image forming apparatus. The inkjet image forming unit and the offset image forming unit are examples of the image forming unit. Even in an image forming apparatus including other image forming units, an image is formed on the paper P, and then The image forming apparatus is not particularly limited as long as it is an image forming apparatus that fixes an image on the paper P by heating and pressing.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14 Image forming part 20 Image forming unit 22 Control part 30 Fixing apparatus (an example of a conveying apparatus)
32 fixing roll (an example of a first rotating body or a second rotating body, an example of a heating body)
34 Pressure belt (an example of a second rotating body or a first rotating body, an example of a pressing body)
35 Shaft (example of shaft)
42 Lever member (an example of a support part)
44 Tension spring 46 Cam follower (example of actuator)
50 Common cam (an example of cam member)
51 1st cam (an example of another cam member)
52 Second cam (an example of a cam member)
54 Ascending surface (example of first surface)
55 Ascending surface (example of third surface)
56 Lowering surface (example of second surface)
60 Braking device (an example of braking means)
61 Notch gear (an example of a notch gear)
64 Torque limiter (example of suppression device)
71 Motor (an example of drive means)
73 Moving gear (an example of moving gear)
74 Transmission gear (an example of a transmission gear)
N nip P paper (example of media)
H Highest point L Lowest point

Claims (8)

A transport unit that transports the medium between a first rotating body that rotates about its own axis and a second rotating body that rotates in contact with the first rotating body;
A cam member configured to move a support portion of the second rotating body by rotating a shaft provided in the own axis direction and move the second rotating body away from and approach the first rotating body; ,
Braking means for braking the shaft while the second rotating body approaches the first rotating body as the cam member rotates;
Conveying device equipped with. The braking means includes
A notch gear that rotates in synchronization with the shaft;
A suppressor connected to a gear and suppressing the rotational force of the shaft,
2. The transport device according to claim 1, wherein the notch gear meshes with the gear while the second rotating body approaches the first rotating body as the cam member rotates. The cam member has a first surface where the distance increases from a position where the distance from the center of the shaft is minimum when viewed from a predetermined rotation direction, and the distance from the position where the distance is maximum. A second surface that decreases,
Another cam member having a third surface having a protruding portion in the radial direction of the shaft on the side where the distance is minimum with respect to the first surface, and the second surface; The other cam member provided in the vicinity,
The braking means includes
With the rotation of the cam member and the other cam member, the second rotating body is approaching the first rotating body and only the other cam member is the second by the third surface. The conveying apparatus according to claim 1, wherein the shaft is braked while the rotating body is separated from the first rotating body. The braking means includes
A notch gear that rotates in synchronization with the shaft;
A suppressor connected to a gear and suppressing the rotational force of the shaft,
The notch gear is connected to the other cam member while the second rotating body is approaching the first rotating body with the rotation of the cam member and the other cam member and by the third surface. The conveying device according to claim 3, wherein only the second rotating body is engaged with the gear while the second rotating body is separated from the first rotating body. The support portion includes an operating portion that comes into contact with the outer peripheral surface of the cam member,
5. The transport device according to claim 2, wherein at least the outer peripheral surface and the operating portion do not contact each other, the notch gear meshes with the gear. The transport apparatus according to any one of claims 1 to 5,
One of the first rotating body and the second rotating body is formed as a heating body, and the other is formed as a pressure body.   An image forming apparatus comprising: an image forming unit; and the fixing device according to claim 6. Driving means for driving the shaft;
A movable gear disposed so as to be able to contact with and separate from a transmission gear connected to the shaft and transmitting power from the driving means to the shaft;
The moving gear is joined to the transmission gear when power is transmitted from the driving means to the shaft, and is separated from the transmission gear when power is transmitted from the shaft to the driving means. The image forming apparatus described in 1.

Images