Drive transmission mechanism, and fixing device and image forming apparatus including same

Abstract

The invention provides a drive transmission mechanism, and a fixing device and an image forming apparatus including the same. The drive transmission mechanism includes a first ratchet mechanism, a second ratchet mechanism, and a link member. The first ratchet mechanism includes a first drive input gear, a first drive output gear, and a first coupling member. The second ratchet mechanism includes a second drive input gear, a second drive output gear, and a second coupling member. The link member moves in a direction away from the first drive output gear by the thrust of the first coupling member, moves the second coupling member in a direction close to the second drive output gear, and moves in a direction away from the second drive output gear by the thrust of the second coupling member. The first coupling member is moved in a direction approaching the first drive output gear.

Description

Technical Field

[0001] The present invention relates to a drive transmission mechanism for transmitting a driving force to a driven member, and to a fixing device and an image forming device including the drive transmission mechanism. Background Art

[0002] In the drive device of image forming devices such as copiers and printers, the prior art often uses the following method, that is, adopting a structure in which the forward and reverse rotations of the motor are transmitted to different units to reduce the switching mechanism such as the clutch. As the switching unit of the transmission object used in these drive devices, the ratchet mechanism and the planetary gear mechanism are representative. The ratchet mechanism is provided with a spiral bevel on the driving gear and the driven gear to perform thrust movement, and the planetary gear mechanism uses the tooth surface force of the transmission to move the position of the gear itself. Summary of the invention 1. Technical issues to be resolved

[0003] An object of the present invention is to provide a drive transmission mechanism and a fixing device and an image forming apparatus including the same, which can maintain the connection state between a ratchet drive portion and a driven member without using a brake using a biasing member such as a spring. (II) Technical solution

[0004] The drive transmission mechanism of the first structure of the present invention is characterized in that it comprises: a first ratchet mechanism, which transmits the rotational driving force from the driving source to the first driven component; a second ratchet mechanism, which transmits the rotational driving force from the driving source to the second driven component, the first ratchet mechanism having: a first drive input gear, which inputs the rotational driving force of the driving source; a first drive output gear, which is arranged on the same axis as the first drive input gear and outputs the rotational driving force of the driving source to the first driven component; and a first connecting component, which is arranged between the first drive input gear and the first drive output gear so as to be thrust-movable and rotate together with the first drive input gear, and the second ratchet mechanism The gear train is a gear train that is coupled to the second transmission gear and has a first gear that is coupled to the second transmission gear and a second gear that is coupled to the second transmission gear. The first ratchet mechanism is configured to engage with the first ratchet tooth and the second ratchet tooth, and when the driving source rotates in the positive direction, the first ratchet mechanism rotates in the direction in which the driving connecting surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other, thereby becoming a driven connecting state in which the driving force is transmitted to the first driven component, and the second ratchet mechanism rotates in the direction in which the non-driving connecting surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other, thereby becoming a non-driven connecting state in which the driving force is not transmitted to the second driven component. When the driving source rotates in the reverse direction, the first ratchet mechanism rotates in the direction in which the non-driving connecting surfaces mesh with each other, thereby becoming a non-driven connecting state in which the driving force is not transmitted to the first driven component, and the second ratchet mechanism rotates in the direction in which the non-driving connecting surfaces mesh with each other The driving connection surface rotates in the direction of meshing, thereby becoming a driving connection state for transmitting driving force to the second driven part. A connecting rod part is arranged between the first ratchet mechanism and the second ratchet mechanism. The connecting rod part assists in switching the driving connection state and the non-driving connection state of the first ratchet mechanism and the second ratchet mechanism. The connecting rod part utilizes the thrust of the first connecting part to move in the direction away from the first drive output gear, so that the second connecting part moves in the direction close to the second drive output gear, and utilizes the thrust of the second connecting part to move in the direction away from the second drive output gear, so that the first connecting part moves in the direction close to the first drive output gear. In addition, the present invention is a fixing device, comprising: a heated rotating body; a pressure member, which is pressed against the heated rotating body with a specified pressure to form a fixing roller gap portion, and transmits a rotational driving force to the heated rotating body to rotate it; a heating mechanism, which heats the heated rotating body; a pressure mechanism, which adjusts the pressure of the pressure member relative to the heated rotating body; a fixing drive gear, which serves as the first driven member and inputs a rotational driving force to the pressure member; an eccentric cam, which serves as the second driven member and drives the pressure mechanism; and a drive transmission mechanism of the above structure, which switches between the transmission of the rotational driving force to the fixing drive gear and the transmission of the rotational driving force to the eccentric cam. In addition, the present invention is an image forming device comprising: an image forming unit, which forms a colorant image on a recording medium; and a fixing device of the above-mentioned structure, which heats and pressurizes the recording medium on which the colorant image is formed by the image forming unit, so that the colorant image is fixed to the recording medium. (III) Beneficial effects

[0005] According to the first structure of the present invention, by providing a connecting rod component that assists the switching of the driving force transmission of the first ratchet mechanism and the second ratchet mechanism, the thrust movement of the first connecting component and the second connecting component can be reliably performed. Therefore, the first connecting component or the second connecting component can be pushed up to the position where the first ratchet tooth meshes with the second ratchet tooth, and the first ratchet mechanism and the second ratchet mechanism can be reliably in a driving connection state. According to the second configuration of the present invention, a fixing device is obtained that can switch, with a simple configuration, between transmission of the rotational driving force to the fixing drive gear that inputs the rotational driving force to the pressure member and transmission of the rotational driving force to the eccentric cam that drives the pressure mechanism. According to the third configuration of the present invention, an image forming apparatus is obtained in which input of driving force to the pressing member and the pressing mechanism of the fixing device can be switched with a simple configuration. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a schematic diagram showing the internal structure of the image forming apparatus 100 . Figure 2 yes Figure 1 A side sectional view of the vicinity of the fixing device 13 in FIG. Figure 3 It is a side view showing the structure of the periphery of the pressure applying mechanism 21 of the fixing device 13 . Figure 41 is a diagram schematically showing the drive transmission mechanism 30 that transmits the drive force to the fixing device 13 , and shows the drive transmission state of the first ratchet mechanism 31 . Figure 5 It is a perspective view of the first ratchet mechanism 31 constituting the drive transmission mechanism 30 . Figure 6 It is a perspective view of the first drive input gear 40 a constituting the first ratchet mechanism 31 . Figure 7 It is a perspective view of the first connecting member 50 a constituting the first ratchet mechanism 31 . Figure 8 It is a perspective view of the first drive output gear 60 a constituting the first ratchet mechanism 31 . Fig. 9 1 is a diagram schematically showing the drive transmission mechanism 30 that transmits the drive force to the fixing device 13 , and shows the drive transmission state of the second ratchet mechanism 32 . DETAILED DESCRIPTION

[0007] (1. Structure of Image Forming Apparatus) Embodiments of the present invention will be described below with reference to the accompanying drawings. Figure 1 1 is a schematic cross-sectional view showing the internal structure of an image forming apparatus 100 equipped with a fixing device 13 according to an embodiment of the present invention. In the main body of the image forming apparatus 100 (here, a color printer), from the upstream side in the conveying direction (in Figure 1 The left side in the middle is provided with four image forming units Pa, Pb, Pc, and Pd in ​​sequence. These image forming units Pa to Pd correspond to different four-color (cyan, magenta, yellow, and black) image settings, and form cyan, magenta, yellow, and black images in sequence through charging, exposure, development, and transfer processes, respectively.

[0008] The image forming sections Pa to Pd are provided with photosensitive drums (image bearing bodies) 1a, 1b, 1c, and 1d for bearing visible images (toner images) of respective colors, and an intermediate transfer belt 8 is provided adjacent to each of the image forming sections Pa to Pd. Figure 1 The toner images formed on the photosensitive drums 1a to 1d are sequentially transferred to the intermediate transfer belt 8 that moves in contact with the photosensitive drums 1a to 1d and overlap each other. Thereafter, the toner images transferred to the intermediate transfer belt 8 are secondarily transferred to a sheet S as an example of a recording medium by a secondary transfer roller 9. Furthermore, the sheet S to which the toner images are secondarily transferred is fixed in the fixing device 13 and then discharged from the main body of the image forming device 100. The photosensitive drums 1a to 1d are moved in the direction shown in the figure by a main motor (not shown). Figure 1 The photosensitive drums 1a to 1d rotate in the clockwise direction as shown, and perform image forming processing on each of the photosensitive drums 1a to 1d.

[0009] The paper S with the toner image transferred thereon is stored in a paper cassette 16 disposed at the lower part of the main body of the image forming apparatus 100, and is transported to the roller gap between the secondary transfer roller 9 and the driving roller 11 of the intermediate transfer belt 8 via the paper feed roller 12a and the registration roller pair 12b. The intermediate transfer belt 8 is made of a sheet of dielectric resin and is mainly a seamless belt. In addition, a scraper-shaped belt cleaner 19 is disposed on the downstream side of the secondary transfer roller 9 to remove the toner and the like remaining on the surface of the intermediate transfer belt 8.

[0010] Next, the image forming units Pa to Pd are described. Around and below the rotatably arranged photosensitive drums 1a to 1d, there are provided charging devices 2a, 2b, 2c and 2d for charging the photosensitive drums 1a to 1d, an exposure device 5 for exposing image information on each photosensitive drum 1a to 1d, developing devices 3a, 3b, 3c and 3d for forming toner images on the photosensitive drums 1a to 1d, and cleaning devices 7a, 7b, 7c and 7d for removing residual developer (toner) and the like on the photosensitive drums 1a to 1d.

[0011] When image data is input from a host device such as a personal computer, first, the surface of the photosensitive drum 1a to 1d is uniformly charged by the charging device 2a to 2d. Then, the exposure device 5 irradiates light according to the image data to form an electrostatic latent image corresponding to the image data on each photosensitive drum 1a to 1d. The developing devices 3a to 3d are respectively filled with a predetermined amount of a two-component developer containing toners of cyan, magenta, yellow, and black. In addition, when the ratio of the toner in the two-component developer filled in each developing device 3a to 3d is lower than a predetermined value due to the formation of the toner image described later, the toner is replenished from the toner container 4a to 4d to each developing device 3a to 3d. The toner in the developer is supplied to the photosensitive drum 1a to 1d by the developing device 3a to 3d and electrostatically adheres to form a toner image corresponding to the electrostatic latent image formed by the exposure of the exposure device 5.

[0012] Then, the primary transfer rollers 6a to 6d are used to apply an electric field between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d at a predetermined transfer voltage, and the cyan, magenta, yellow, and black toner images on the photosensitive drums 1a to 1d are primarily transferred to the intermediate transfer belt 8. These four-color images are formed in a predetermined positional relationship to form a predetermined full-color image. After that, in preparation for the subsequent formation of a new electrostatic latent image, the toners and the like remaining on the surfaces of the photosensitive drums 1a to 1d after the primary transfer are removed by the cleaning devices 7a to 7d.

[0013] The intermediate transfer belt 8 is mounted on the driven roller 10 on the upstream side and the driving roller 11 on the downstream side. The driving roller 11 is rotated by a belt driving motor (not shown). When the intermediate transfer belt 8 starts to rotate counterclockwise with the rotation of the driving roller 11, the paper S is transported from the registration roller pair 12b to the roller gap portion (secondary transfer roller gap portion) between the driving roller 11 and the secondary transfer roller 9 disposed adjacent thereto at a predetermined timing, and the full-color image on the intermediate transfer belt 8 is secondarily transferred to the paper S. The paper S to which the toner image is secondarily transferred is transported to the fixing device 13.

[0014] The fixing roller 131 and the pressure roller 132 (see Figure 2 ) heats and pressurizes the paper S conveyed to the fixing device 13, so that the toner image is fixed on the surface of the paper S to form a predetermined full-color image. The paper S with the full-color image formed thereon is assigned a conveying direction by a branching portion 14 that branches in multiple directions, and is discharged to a discharge tray 17 directly (or after being conveyed to a double-sided conveying path 18 and having images formed on both sides) by a discharge roller pair 15.

[0015] (2. Structure of the fixing device) Figure 2 yes Figure 1 1 is a side cross-sectional view of the periphery of the fixing device 13 in the image forming apparatus 100. The fixing device 13 is a fixing device that uses a heat source of an electromagnetic induction heating method, and includes: a fixing roller 131 as a heating member, a pressure roller 132 as a pressure rotating body, an induction heating portion 133 disposed opposite to the outer periphery of the fixing roller 131, and a temperature sensor 134. The temperature sensor 134 is composed of a thermistor or the like, and detects the surface temperature of the fixing roller 131. The induction heating portion 133 and the temperature sensor 134 are fixed to the main body of the image forming apparatus 100, and the fixing roller 131 and the pressure roller 132 are rotatably held in the housing of the fixing device 13.

[0016] The fixing roller 131 comprises: a base material, which is made of cylindrical stainless steel; an elastic layer, which is made of silicone rubber sponge and is used to impart elasticity to the fixing roller gap portion N that is pressed against the pressure roller 132; and a release layer, which is made of fluorine-based resin and imparts release properties to the elastic layer (neither of which is shown in the figure). Between the base material and the elastic layer, an insulating layer and an induction heating layer are provided in sequence from the base material side (neither of which is shown in the figure).

[0017] The pressure roller 132 includes: a shaft 132a, which is made of aluminum; an elastic layer 132b, which is formed on the base material 132a and consists of silicone rubber, and is used to impart elasticity to the fixing roller gap portion N; and a release layer (not shown), which covers the surface of the elastic layer 132b and is composed of a fluororesin tube, and is used to improve the release property when the unfixed colorant image is melted and fixed through the fixing roller gap portion N.

[0018] The pressure roller 132 is driven by the fixing drive motor 20 (see Figure 4 ) is driven to rotate, and the pressurizing mechanism 21 (refer to Figure 3 ) is pressed toward the radial center of the fixing roller 131. Thus, when the pressure roller 132 is pressed against the fixing roller 131 and the pressure roller 132 rotates, the fixing roller 131 is driven to rotate in the same direction in the fixing nip portion N.

[0019] The temperature sensor 134 is disposed so as to face the following regions, and detects the temperature of each region: the paper feeding region in the central portion in the axial direction (width direction) of the fixing roller 131 and the axial ends which become non-paper feeding regions when conveying small-sized paper such as A4 longitudinal size. The power supplied to the induction heating portion 133 is controlled based on the temperature detected by the temperature sensor 134, so that the surface of the fixing roller 131 is kept at a predetermined temperature.

[0020] The induction heating unit 133 includes an exciting coil 133a, a winding shaft 133b, and an iron core 133c, and heats the fixing roller 131 by electromagnetic induction. The induction heating unit 133 extends in the axial direction of the fixing roller 131 and is disposed opposite to the fixing roller 131 so as to surround a portion of the outer circumference of the fixing roller 131.

[0021] The excitation coil 133a made of copper wire is wound around the winding shaft 133b and is arranged in a spiral shape around a part of the outer periphery of the fixing roller 131 in a manner that it is axially wound around the central part of the iron core 133c. The excitation coil 133a is connected to a high-voltage power supply (not shown) and generates magnetic flux using the high-frequency current supplied by the power supply. The magnetic flux generated by the induction heating unit 133 is Figure 2 The magnetic flux is emitted in a direction parallel to the paper surface and penetrates the induction heating layer of the fixing roller 131. Eddy current is generated around the magnetic flux of the induction heating layer. When the eddy current flows, Joule heat is generated due to the resistance in the induction heating layer, so that the induction heating layer is heated.

[0022] The power of the high voltage power source is controlled according to the temperature detected by the temperature sensor 134 so that the fixing roller 131 reaches a predetermined temperature by the induction heating portion 133. When the fixing roller 131 is heated and raised to a predetermined temperature, the paper S sandwiched by the fixing nip portion N is heated and pressed by the pressure roller 132, so that the unfixed toner image on the paper S is melted and fixed.

[0023] The paper S with the toner image fixed thereon is discharged from the discharge roller pair 15 to the discharge tray 17 (see also Figure 1 ). The linear velocity of the fixing conveying roller pair 135 is set to be slightly faster than the linear velocity of the fixing roller 131 and the pressure roller 132 to avoid deflection of the conveyed paper S.

[0024] Figure 3 1 is a side view showing the structure of the pressure mechanism 21 and the surroundings of the fixing device 13. A fixing drive gear 136 is fixed to the rotating shaft 132a of the pressure roller 132. The drive transmission mechanism 30 (see FIG. 1 ) is connected to the fixing drive gear 136. Figure 4 )'s first drive output gear 60a.

[0025] The pressure mechanism 21 includes a pressure plate 211, a pressure spring 212, and an eccentric cam 213. The pressure plate 211 is disposed opposite to the bearing portion 137 of the pressure roller 132. The fulcrum portion 211a of the pressure plate 211 is fixed to a housing (not shown) of the fixing device 13, and the pressure plate 211 can swing in a direction approaching or separating from the bearing portion 137. The pressure spring 212 is disposed on the opposite side of the bearing portion 137 across the pressure plate 211, and applies force in a direction approaching the bearing portion 137.

[0026] The eccentric cam 213 is disposed on the opposite side of the pressure spring 212 across the pressure plate 211. The eccentric cam 213 is integrally formed with the drive transmission mechanism 30 (see Figure 4 ) When the eccentric cam 213 rotates together with the second drive output gear 60b, the diameter of the eccentric cam 213 abutting against the pressure plate 211 changes.

[0027] More specifically, if Figure 3 When the small diameter portion of the eccentric cam 213 faces the pressure plate 211, a certain pressure is applied from the pressure plate 211 to the bearing portion 137 due to the force of the pressure spring 212. Figure 3 The eccentric cam 213 is rotated a predetermined amount from the state of being in contact with the pressure plate 211, and as the outer diameter of the eccentric cam 213 in contact with the pressure plate 211 increases, the pressure plate 211 overcomes the force of the pressure spring 212 and is pressed in the direction away from the bearing portion 137. As a result, the pressure spring 212 is compressed, and the pressure acting from the pressure plate 211 to the bearing portion 137 is weakened. That is, the pressing force of the pressure roller 132 relative to the fixing roller 131 can be adjusted by the rotation amount (rotation angle) of the eccentric cam 213.

[0028] (3. Structure of drive transmission mechanism) Figure 4 2 is a diagram schematically showing a drive transmission mechanism 30 for transmitting a driving force to the fixing device 13. Figure 4 As shown, the drive transmission mechanism 30 includes a first ratchet mechanism 31 , a second ratchet mechanism 32 , and a link member 33 .

[0029] The first ratchet mechanism 31 includes a first drive input gear 40a, a first connecting member 50a, and a first drive output gear 60a. Regarding the first ratchet mechanism 31, the first drive input gear 40a is connected to the fixing drive motor 20, and the first drive output gear 60a is connected to the fixing drive gear 136, and transmits the rotational drive force to the pressure roller 132 via the fixing drive gear 136.

[0030] The second ratchet mechanism 32 includes a second drive input gear 40b, a second connecting member 50b, and a second drive output gear 60b. Regarding the second ratchet mechanism 32, the second drive input gear 40b is connected to the fixing drive motor 20, and further connected to the pressure mechanism 21 via the eccentric cam 213 integrally formed on the second drive output gear 60b (both refer to Figure 3 ), transmitting driving force to the pressurizing mechanism 21.

[0031] The link member 33 is arranged between the first link member 50a of the first ratchet mechanism 31 and the second link member 50b of the second ratchet mechanism 32. The link member 33 has both ends that swing in the vertical direction around a swing support shaft 33a provided at the center in the longitudinal direction. The link member 33 swings by the thrust movement of the first link member 50a and the second link member 50b, thereby assisting the switching of the driving force transmission between the first ratchet mechanism 31 and the second ratchet mechanism 32.

[0032] Figure 5 It is a perspective view of the first ratchet mechanism 31 constituting the drive transmission mechanism 30 . Figure 6 to Figure 8 1 is a perspective view of the first drive input gear 40a, the first connecting member 50a, and the first drive output gear 60a that constitute the first ratchet mechanism 31. Figures 5 to 8 The structure of the first ratchet mechanism 31 will be described. In addition, the second drive input gear 40b, the second connecting member 50b, and the second drive output gear 60b (all refer to Figure 4 ) is also related to Figure 6 to Figure 8 Exactly the same structure.

[0033] like Figure 6 As shown in FIG. 1 , the first drive input gear 40a includes: a gear body 41, a boss portion 42, a slope 43, a first rotation limiting portion 44, and a second rotation limiting portion 45. Gear teeth (not shown) are formed on the outer peripheral surface of the gear body 41. The boss portion 42 is formed on the rotation axis of the gear body 41 for the shaft portion 62 (see FIG. 1 ) of the first drive output gear 60a. Figure 8 ) is inserted in a rotatable manner.

[0034] The inclined surface 43 is a surface facing the first connection member 50a and is formed in a spiral shape between the gear body 41 and the boss portion 42. The first rotation restricting portion 44 and the second rotation restricting portion 45 are vertical surfaces formed at the uppermost and lowermost portions of the inclined surface 43, respectively.

[0035] The first drive input gear 40a and the pinion gear 22 (see Figure 4 ) is engaged with the pinion gear 22, which is fixed to the output shaft of the fixing drive motor 20. The first drive input gear 40a is also engaged with the second drive input gear 40b (refer to FIG. 1 ) constituting the second ratchet mechanism 32. Figure 4 ) engagement.

[0036] like Figure 7 As shown, the first connection member 50a includes a main body 51, a first ratchet tooth 52, a leg 53, a first rotation restricting surface 54, a second rotation restricting surface 55, and a flange 56. The main body 51 is cylindrical and has a through hole 51a.

[0037] A plurality of first ratchet teeth 52 (six in this embodiment) are formed at the upper end of the main body 51. Each first ratchet tooth 52 has a substantially vertical drive coupling surface 52a and a non-drive coupling surface 52b inclined downward at a predetermined angle from the upper end of the drive coupling surface 52a.

[0038] The leg portion 53 is formed at the lower end of the main body portion 51. The leg portion 53 contacts the inclined surface 43 of the first drive input gear 40a. As the first drive input gear 40a rotates, the leg portion 53 moves in the vertical direction along the inclined surface 43. Thus, the first connecting member 50a is configured to be capable of thrust movement relative to the first drive input gear 40a.

[0039] The first rotation restricting surface 54 and the second rotation restricting surface 55 are respectively formed at one end side and the other end side in the circumferential direction of the leg portion 53. The first rotation restricting surface 54 abuts against the first rotation restricting portion 44 of the first drive input gear 40a. The second rotation restricting surface 55 abuts against the second rotation restricting portion 45 of the first drive input gear 40a.

[0040] The flange portion 56 is formed in an annular shape on the outer peripheral surface of the main body portion 51. Figure 4 ) abuts against the lower surface of the flange portion 56.

[0041] like Figure 8 As shown, the first drive output gear 60a includes a gear body 61, a shaft portion 62, and a second ratchet tooth 63. A toothed portion 64 is formed on the outer peripheral surface of the gear body 61 to be aligned with the fixing drive gear 136 (see Figure 4) meshing gear teeth (not shown). The shaft portion 62 is formed on the rotation axis of the gear body 61 and is rotatably inserted into the through hole 51a of the first connecting member 50a and the boss portion 42 of the first drive input gear 40a.

[0042] A plurality of second ratchet teeth 63 (six in this embodiment) are formed at the lower end of the gear body 61. The second ratchet teeth 63 mesh with the first ratchet teeth 52 of the first connecting member 50a. Each second ratchet tooth 63 has a substantially vertical drive connecting surface 63a and a non-drive connecting surface 63b that is inclined upward at a predetermined angle from the lower end of the drive connecting surface 63a.

[0043] The shaft portion 62 of the first drive output gear 60a is inserted into the through hole 51a of the first connecting member 50a and the boss portion 42 of the first drive input gear 40a, so that the first drive input gear 40a, the first connecting member 50a, and the first drive output gear 60a are arranged coaxially.

[0044] The first drive output gear 60a utilizes the thrust movement of the first connecting member 50a to switch to the following states, namely: a driven connection state in which the drive connection surface 52a of the first ratchet tooth 52 is meshed with the drive connection surface 63a of the second ratchet tooth 63, and a non-driven connection state in which the non-driven connection surface 52b of the first ratchet tooth 52 is opposite to the non-driven connection surface 63b of the second ratchet tooth 63.

[0045] (4. Switching process of drive transmission using drive transmission mechanism) Next, the switching process of the drive transmission to the fixing device 13 using the drive transmission mechanism 30 will be described. When the pressure roller 132 of the fixing device 13 is driven to rotate, as shown in FIG. Figure 4 As shown, the fixing drive motor 20 is rotated forward to move the first drive input gear 40a of the first ratchet mechanism 31 to the Figure 6 Clockwise direction (outer surface is Figure 4 As the first drive input gear 40a rotates, the leg portion 53 of the first connecting member 50a begins to rise along the inclined surface 43 of the first drive input gear 40a.

[0046] When the leg portion 53 rises to the highest point along the inclined surface 43, the first rotation limiting surface 54 of the first connecting member 50a contacts the first rotation limiting portion 44 of the first drive input gear 40a, and the rotational driving force is transmitted from the first drive input gear 40a to the first connecting member 50a. Figure 7 Clockwise direction (outer surface is Figure 4 direction of movement from right to left).

[0047] In addition, since the first connecting member 50a rises along the inclined surface 43, the first ratchet mechanism 31 enters a drive connection state in which the drive connection surface 52a of the first ratchet tooth 52 meshes with the drive connection surface 63a of the second ratchet tooth 63. Figure 7 Clockwise direction (outer surface is Figure 4 The fixing drive gear 136 rotates (in the direction of movement from right to left), transmitting the rotational driving force to the fixing drive gear 136.

[0048] On the other hand, the second drive input gear 40b of the second ratchet mechanism 32 rotates toward the Figure 6 Counterclockwise direction (outer surface is Figure 4 As the second drive input gear 40b rotates, the leg portion 53 of the second connecting member 50b begins to descend along the inclined surface 43 of the second drive input gear 40b.

[0049] When the leg 53 descends to the lowest position along the inclined surface 43, the second rotation limiting surface 55 of the second connecting member 50b contacts the second rotation limiting portion 45 of the second drive input gear 40b, and the rotational driving force is transmitted from the second drive input gear 40b to the second connecting member 50b. Figure 7 Counterclockwise direction (outer surface is Figure 4 The direction of movement from left to right) rotates.

[0050] In addition, since the second connecting member 50b descends along the inclined surface 43, the second ratchet mechanism 32 is in a non-driven connection state in which the non-driven connection surface 52b of the first ratchet tooth 52 and the non-driven connection surface 63b of the second ratchet tooth 63 are opposite to each other. As a result, the rotational driving force is not transmitted from the second connecting member 50b to the second drive output gear 60b, and the driving force is not transmitted to the pressurizing mechanism 21.

[0051] In addition, the non-drive connecting surface 52b and the non-drive connecting surface 63b are both inclined toward the downstream side in the rotation direction. Therefore, when the second connecting member 50b rotates in a state where the non-drive connecting surface 52b and the non-drive connecting surface 63b are in contact, the second connecting member 50b uses the vertical downward component of the resistance force acting between the non-drive connecting surface 52b and the non-drive connecting surface 63b to move in a direction away from the second drive output gear 60b (downward).

[0052] Thus, the flange portion 56 formed on the second connecting member 50b is connected to the one end side ( Figure 4 As a result, the other end side ( Figure 4 The left end of the first connecting member 50a is pushed up with the flange portion 56 thereof.

[0053] Next, a case where the pressing mechanism 21 of the pressing roller 132 is driven will be described. Fig. 9 FIG. 2 is a diagram schematically showing the drive transmission mechanism 30 for transmitting the driving force to the fixing device 13, and shows the drive transmission state of the second ratchet mechanism 32. Figure 4 The fixing drive motor 20 is reversed to move the first drive input gear 40a of the first ratchet mechanism 31 to the Figure 6 Counterclockwise direction (outer surface is Fig. 9 As the first drive input gear 40a rotates, the leg portion 53 of the first connecting member 50a begins to descend along the inclined surface 43 of the first drive input gear 40a.

[0054] When the leg portion 53 descends to the lowest position along the inclined surface 43, the second rotation limiting surface 55 of the first connecting member 50a contacts the second rotation limiting portion 45 of the first drive input gear 40a, and the rotational driving force is transmitted from the first drive input gear 40a to the first connecting member 50a. Figure 7 Counterclockwise direction (outer surface is Fig. 9 The direction of movement from left to right) rotates.

[0055] In addition, since the first connecting member 50a descends along the inclined surface 43, the first ratchet mechanism 31 is in a non-driven connection state in which the non-driven connection surface 52b of the first ratchet tooth 52 faces the non-driven connection surface 63b of the second ratchet tooth 63. As a result, the rotational driving force is not transmitted from the first connecting member 50a to the first drive output gear 60a, and the driving force is not transmitted to the fixing drive gear 136.

[0056] In addition, the non-drive connecting surface 52b and the non-drive connecting surface 63b are both inclined toward the downstream side in the rotation direction. Therefore, when the first connecting member 50a rotates in a state where the non-drive connecting surface 52b and the non-drive connecting surface 63b are in contact, the first connecting member 50a uses the vertical downward component of the resistance force acting between the non-drive connecting surface 52b and the non-drive connecting surface 63b to move in a direction away from the first drive output gear 60a (downward).

[0057] Thus, the flange portion 56 formed on the first connecting member 50a is connected to the other end side ( Fig. 9 As a result, one end side ( Fig. 9 The flange portion 56 of the second connecting member 50b is pushed up.

[0058] On the other hand, the second drive input gear 40b of the second ratchet mechanism 32 rotates toward the Figure 8Clockwise direction (outer surface is Fig. 9 As the second drive input gear 40b rotates, the leg portion 53 of the second connecting member 50b begins to rise along the inclined surface 43 of the second drive input gear 40b.

[0059] When the leg portion 53 rises to the highest point along the inclined surface 43, the first rotation limiting surface 54 of the second connecting member 50b contacts the first rotation limiting portion 44 of the second drive input gear 40b, and the rotational driving force is transmitted from the second drive input gear 40b to the second connecting member 50b. Figure 7 Clockwise direction (outer surface is Fig. 9 direction of movement from right to left).

[0060] In addition, since the second connecting member 50b rises along the inclined surface 43, the second ratchet mechanism 32 enters a drive connection state in which the drive connection surface 52a of the first ratchet tooth 52 meshes with the drive connection surface 63a of the second ratchet tooth 63. Figure 8 Clockwise direction (outer surface is Fig. 9 The second drive output gear 60b rotates (in the direction of movement from right to left), and transmits the rotational driving force to the pressing mechanism 21 of the pressing roller 132 via the eccentric cam 213 integrally formed on the second drive output gear 60b.

[0061] According to the structure of this embodiment, the drive transmission mechanism 30 switches the transmission of the driving force to the fixing drive gear 136 and the pressure mechanism 21 by using the first ratchet mechanism 31 and the second ratchet mechanism 32, so that the transmission of the driving force to the fixing drive gear 136 and the pressure mechanism 21 can be switched by rotating the fixing drive motor 20 forward or reverse. Therefore, the rotation drive of the pressure roller 132 and the adjustment of the pressing force with respect to the fixing roller 131 can be performed by using one fixing drive motor 20, and compared with the structure in which the motors are provided separately, the cost can be reduced and the control path can be simplified.

[0062] Furthermore, by providing the link member 33 that assists the switching of the drive force transmission between the first ratchet mechanism 31 and the second ratchet mechanism 32 , the thrust movement of the first connection member 50 a and the second connection member 50 b can be reliably performed.

[0063] Therefore, regardless of the posture of the connecting rod part 33, even if the first connecting part 50a or the second connecting part 50b rotates following the first drive input gear 40a or the second drive input gear 40b without rising along the inclined surface 43, the first connecting part 50a or the second connecting part 50b can be pushed up to the position where the first ratchet tooth 52 and the second ratchet tooth 63 engage with each other, so that the first ratchet mechanism 31 and the second ratchet mechanism 32 can be reliably put into a drive connection state.

[0064] In addition, for example, when the pinion 22 is arranged between the first drive input gear 40a and the second drive input gear 40b, the first drive input gear 40a and the second drive input gear 40b rotate in the same direction. In this case, it is necessary to make the phases of the first drive input gear 40a and the first connecting member 50a constituting the first ratchet mechanism 31 and the second drive input gear 40b and the second connecting member 50b constituting the second ratchet mechanism 32 opposite to each other.

[0065] Therefore, in the present embodiment, the first drive input gear 40a of the first ratchet mechanism 31 and the second drive input gear 40b of the second ratchet mechanism 32 are connected so that the first drive input gear 40a and the second drive input gear 40b rotate in opposite directions, and the pinion 22 of the fixing drive motor 20 is connected to the first drive input gear 40a. As a result, the first drive input gear 40a and the first connecting member 50a constituting the first ratchet mechanism 31 can be used in common with the second drive input gear 40b and the second connecting member 50b constituting the second ratchet mechanism 32, and the number of components can be reduced.

[0066] In addition, the present invention is not limited to the above-mentioned embodiment, and various changes can be made within the scope of the present invention. For example, although the eccentric cam 213 is integrally formed on the second drive output gear 60b in the above-mentioned embodiment, the second drive output gear 60b can also be fixed to the rotating shaft of the eccentric cam 213. Alternatively, gear teeth can be formed on the outer peripheral surface of the eccentric cam 213 and connected to the second drive output gear 60b directly or via an idler gear.

[0067] Although the description has been made of a case where the drive transmission mechanism 30 is used to switch the drive force transmission between the fixing drive gear 136 of the fixing device 13 and the pressing mechanism 21, the present invention is not limited to the fixing device 13. For example, the drive transmission mechanism 30 may be used to switch the toner replenishment operation between two developing units and two toner containers.

[0068] The present invention can be used for a drive transmission mechanism for transmitting driving force to a driven component. By using the present invention, a drive transmission mechanism and a fixing device having the same can be provided, which can maintain the connection state between the ratchet drive unit and the driven component without using a brake based on a force applying component such as a spring.

Claims

1. A drive transmission mechanism, comprising: a first ratchet mechanism that transmits a rotational driving force from a driving source to a first driven member; a second ratchet mechanism that transmits the rotational driving force from the driving source to the second driven member, The drive transmission mechanism is characterized in that: The first ratchet mechanism has: a first drive input gear which inputs the rotational drive force of the drive source; a first drive output gear, which is coaxially arranged with the first drive input gear and outputs the rotational drive force of the drive source to the first driven member; as well as a first connecting member which is disposed between the first drive input gear and the first drive output gear so as to be thrust movable and rotates together with the first drive input gear; The second ratchet mechanism has: a second drive input gear which inputs the rotational drive force of the drive source; a second drive output gear, which is coaxially arranged with the second drive input gear and outputs the rotational drive force of the drive source to the second driven member; as well as a second connecting member which is disposed between the second drive input gear and the second drive output gear so as to be thrust movable and rotates together with the second drive input gear; The first connecting member and the second connecting member each have a first ratchet tooth formed on a surface facing the first drive output gear or the second drive output gear. The first drive output gear and the second drive output gear each have a second ratchet tooth formed on a surface facing the first connecting member or the second connecting member and meshing with the first ratchet tooth. When the driving source rotates in the positive direction, The first ratchet mechanism is rotated in a direction in which the drive connection surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other, thereby being in a drive connection state in which a drive force is transmitted to the first driven member. The second ratchet mechanism is rotated in a direction in which the non-driving connection surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other, thereby being in a non-driving connection state in which the driving force is not transmitted to the second driven member. When the driving source rotates in the reverse direction, The first ratchet mechanism is rotated in a direction to mesh with the non-driving coupling surface, thereby being in a non-driving coupling state in which a driving force is not transmitted to the first driven member. The second ratchet mechanism is rotated in a direction to mesh with the drive coupling surface, thereby being in a drive coupling state in which a driving force is transmitted to the second driven member. A link member is disposed between the first ratchet mechanism and the second ratchet mechanism, and the link member assists in switching between the drive connection state and the non-drive connection state of the first ratchet mechanism and the second ratchet mechanism. The connecting rod component utilizes the thrust of the first connecting component to move in the direction away from the first drive output gear, so that the second connecting component moves in the direction close to the second drive output gear, and utilizes the thrust of the second connecting component to move in the direction away from the second drive output gear, so that the first connecting component moves in the direction close to the first drive output gear.

2. The drive transmission mechanism according to claim 1, characterized in that: The first connecting member and the second connecting member have flange portions protruding from the outer peripheral surface in an annular shape. The two ends of the connecting rod member in the longitudinal direction are arranged opposite to the surfaces of the first drive output gear and the second drive output gear of the flange portion, and the connecting rod member is supported so as to be able to swing in the axial direction with the central portion in the longitudinal direction as a swing fulcrum. When the first connecting member is thrust-moved in a direction away from the first drive output gear, the flange portion of the first connecting member pushes one end portion of the link member toward the first drive input gear, so that the second connecting member is pushed toward the second drive output gear. When the second connecting member is thrust-moved in a direction away from the second drive output gear, the flange portion of the second connecting member pushes the other end of the link member toward the second drive input gear, so that the first connecting member is pushed toward the first drive output gear.

3. The drive transmission mechanism according to claim 1, characterized in that: The first and second connecting members are thrust-moved in a direction away from the first drive output gear or the second drive output gear by utilizing a component of a resistance force of the first and second ratchet teeth acting on the non-drive connecting surface that acts vertically downward.

4. The drive transmission mechanism according to claim 1, characterized in that: The first drive input gear and the second drive input gear each have an inclined surface on a surface facing the first connecting member or the second connecting member, wherein the inclined surface extends in the circumferential direction and is inclined in the vertical direction. The first connecting member and the second connecting member have legs at their lower ends facing the inclined surface. The first connecting member and the second connecting member are moved in the thrust direction by rotating relative to the first drive input gear and the second drive input gear in a state in which the leg portions are in contact with the inclined surfaces.

5. The drive transmission mechanism according to claim 4, characterized in that: A first rotation limiting portion and a second rotation limiting portion consisting of vertical surfaces are respectively formed at the uppermost portion and the lowermost portion of the inclined surface. The leg portion is formed with a first rotation restricting surface facing the first rotation restricting portion and a second rotation restricting surface facing the second rotation restricting portion. When the first rotation limiting portion contacts the first rotation limiting surface and the first connecting member and the second connecting member rotate together with the first drive input gear or the second drive input gear, the drive connecting surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other. When the second rotation restricting portion contacts the second rotation restricting surface and the first and second connecting members rotate together with the first drive input gear or the second drive input gear, the non-drive connecting surfaces of the first ratchet tooth and the second ratchet tooth mesh with each other.

6. The drive transmission mechanism according to claim 1, characterized in that: The first drive input gear is meshed with the second drive input gear, The rotational driving force of the driving source is directly input to the first driving input gear, and the rotational driving force of the driving source is input to the second driving input gear via the first driving input gear.

7. A fixing device comprising: A heated rotating body; a pressurizing member that is pressed against the heated rotating body at a predetermined pressure to form a fixing nip portion, and transmits a rotational driving force to the heated rotating body to rotate; A heating mechanism, which heats the heated rotating body; A pressing mechanism that adjusts the pressing force of the pressing member relative to the heated rotating body; a fixing drive gear, which serves as the first driven member and inputs a rotational driving force to the pressing member; an eccentric cam, which serves as the second driven component and drives the pressurizing mechanism; as well as The drive transmission mechanism according to any one of claims 1 to 6 switches between transmission of the rotational driving force to the fixing drive gear and transmission of the rotational driving force to the eccentric cam.

8. An image forming device comprising: an image forming unit that forms a toner image on a recording medium; and The fixing device according to claim 7, wherein the recording medium on which the toner image is formed by the image forming section is heated and pressurized to fix the toner image to the recording medium.

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