JP2023023111A - Drive transmission device, fixing device, and image forming apparatus - Google Patents

Abstract

To provide a drive transmission device that can easily maintain the constant center distance between gears that mesh with each other.SOLUTION: A drive transmission device 50 comprises: a drive gear 51 that receives a driving force from a drive motor and rotates centered on a drive shaft 52; a transmission gear 53 that meshes with the drive gear 51 and rotates centered on a transmission shaft 42 in association with the rotation of the drive gear 51; a drive contact member 60 that has a drive contact surface 63 curved in a concentric circular shape with the drive gear 51, and is provided non-rotatably on the same axis with the drive shaft 52; a transmission contact member 65 that has a transmission contact surface 67 curved in a concentric circular shape with the transmission gear 53, and is provided non-rotatably on the same axis with the transmission shaft 42 at a position where the transmission contact surface 67 is brought into contact with the drive contact surface 63; and an urging member 54 that urges the transmission shaft 42 toward the drive shaft 52, and maintains a state in which the transmission contact surface 67 and the drive contact surface 63 are in contact with each other.SELECTED DRAWING: Figure 4

Description

The present invention relates to a drive transmission device, a fixing device, and an image forming apparatus that maintain a constant distance between gears meshing with each other.

An image forming apparatus has been disclosed that maintains an inter-axis distance between gears that rotationally drive a developing sleeve (Patent Document 1). A rotating shaft of the developing sleeve extends outward from the developing container, and a sleeve gear is fixed to the tip side thereof. A development drive gear rotatably supported by a drive side plate is meshed with the sleeve gear. The rotation shaft of the developing sleeve extends further outside than the sleeve gear and is supported by bearings. Since the bearing rests on a base formed by cutting and raising a part of the driving side plate, the sleeve gear does not move away from the developing drive gear, and the axial distance between the sleeve gear and the developing drive gear is maintained.

JP-A-8-314215

However, in the above technique, sufficient consideration has not been given to the movement of the sleeve gear in the direction approaching the development driving gear. Also, in order to keep the distance between the shafts of the sleeve gear and the development drive gear accurate, the drive side plate must be formed with high accuracy and positioned accurately, such as the position where the development drive gear is supported and the position where the base is formed. is the premise, and there is a problem that the manufacturing of such a drive side plate requires a great deal of cost.

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a drive transmission device, a fixing device, and an image forming apparatus that can easily maintain a constant distance between gears that mesh with each other.

The drive transmission device of the present invention includes a drive gear that receives a driving force from a drive source and rotates about a drive shaft, and a transmission gear that meshes with the drive gear and rotates about the transmission shaft as the drive gear rotates. a gear; a drive contact member having a drive contact surface curved concentrically with the drive gear and non-rotatably provided on the same axis as the drive shaft; and a transmission contact curved concentrically with the transmission gear. a transmission contact member having a surface and non-rotatably provided on the same axis as the transmission shaft at a position where the transmission contact surface contacts the drive contact surface; and one of the drive shaft and the transmission shaft. toward the other of the drive shaft and the transmission shaft to keep the transmission contact surface and the drive contact surface in contact with each other.

In this case, the drive contact surface may have a curved surface that matches the pitch circle of the drive gear, and the transmission contact surface may have a curved surface that matches the pitch circle of the transmission gear.

In this case, the drive shaft is non-rotatably supported by a support member provided on one side in the axial direction, and the drive gear is rotatably supported by the drive shaft at a position facing the support member. The contact member may be fixed to the drive shaft between the regulating member provided on the other side in the axial direction and the drive gear.

The fixing device of the present invention includes the drive transmission device described above, a fixing member that heats a toner image on a medium while rotating around its axis, and a pressure area formed between the fixing member while rotating around its axis. a pressure member that presses toner on the medium passing through the pressure area; a discharge roller that rotates about the transmission shaft and conveys the medium that has passed through the pressure area; and the transmission gear. rotatably supports the transmission shaft to which is fixed, moves in the opening direction to disengage the transmission gear from the driving gear, and moves in the closing direction to connect the transmission gear to the driving gear. and an engaging fixing cover, wherein the biasing member biases the fixing cover toward the closing direction.

An image forming apparatus of the present invention includes the fixing device described above.

According to the present invention, it is possible to easily keep the distance between the axes of gears meshing with each other constant.

1 is a cross-sectional view (front view) schematically showing the interior of an image forming apparatus according to an embodiment of the present invention; FIG. 1 is a sectional view (front view) showing a fixing device, a conveying device, etc. of an image forming apparatus according to an embodiment of the present invention; FIG. 1 is a perspective view showing a fixing device according to an embodiment of the invention; FIG. 3 is a plan view showing the rear portion of the fixing device according to one embodiment of the present invention; FIG. 1 is a perspective view showing a drive contact member of a drive transmission device according to one embodiment of the present invention; FIG. 1 is a front view showing a drive transmission device according to an embodiment of the invention; FIG. 1 is a front view showing an enlarged part of a drive transmission device according to an embodiment of the present invention; FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings. Note that Fr, Rr, L, R, U, and D shown in the drawings indicate front, rear, left, right, up, and down. Terms indicating direction and position are used in this specification, but these terms are used for convenience of description and are not intended to limit the technical scope of the present invention.

An image forming apparatus 1 according to an embodiment will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a cross-sectional view (front view) showing the outline of the inside of the image forming apparatus 1. As shown in FIG. FIG. 2 is a sectional view (front view) showing the fixing device 12, the conveying device 13, and the like.

[Image forming apparatus]
The image forming apparatus 1 is a color printer that forms an image by transferring a full-color toner image formed by electrophotography onto a sheet S (medium). As shown in FIG. 1, the image forming apparatus 1 includes an apparatus main body 2 having a substantially rectangular parallelepiped appearance. A cassette 3 for containing sheets S is detachably provided at the bottom of the device main body 2 , and a paper discharge tray 4 for discharging the paper S on which an image has been formed is provided on the upper surface of the device main body 2 . Four toner containers 5 containing replenishment toner (developer) of four colors (magenta, cyan, yellow, and black) are detachably mounted below the discharge tray 4 . Note that the medium is not limited to the sheet S made of paper, and may be a resin sheet or the like.

A transport path 6 and a reversing transport path 7 serving as a path for transporting the sheet S are formed on the right side inside the apparatus main body 2 . The transport path 6 is formed in a substantially S-shape along the vertical direction, and is a path for transporting the sheet S from the cassette 3 to the discharge tray 4 . The reversing conveying path 7 branches rightward on the downstream side of the conveying path 6 and extends downward to merge with the upstream side of the conveying path 6 . The reversing conveying path 7 is a path for reversing the sheet S and reconveying it to the image forming device 11 which will be described later. In this specification, the terms "upstream" and "downstream" refer to "upstream" and "downstream" in the transport direction of the paper S (medium).

Further, inside the device main body 2, a paper feeding device 10, an image forming device 11, a fixing device 12, and a conveying device 13 are provided. The sheet feeding device 10 is provided at the upstream end of the transport path 6 and has a function of separating the sheets S accommodated in the cassette 3 one by one and feeding them to the transport path 6 . The fixing device 12 is provided on the downstream side of the transport path 6, and has a function of thermally fixing the toner image on the paper S by passing the paper S between the fixing belt 25 rotating around the axis and the pressure roller 26. have. The image forming device 11 is provided between the paper feeding device 10 and the fixing device 12 on the transport path 6 . The conveying device 13 is provided in the conveying path 6 and the reverse conveying path 7 and has a function of conveying the sheet S. As shown in FIG.

<Image forming device>
The image forming device 11 has an intermediate transfer belt 14 , four drum units 15 and an optical scanning device 16 . The intermediate transfer belt 14 is provided below the toner container 5, is stretched over a plurality of rollers, and rotates in the direction indicated by the arrow in FIG. The four drum units 15 are arranged horizontally below the intermediate transfer belt 14 , and the optical scanning device 16 is provided below the drum units 15 . Since the four drum units 15, which correspond to four colors of toner, have the same structure, one drum unit 15 will be described below.

The drum unit 15 has a photosensitive drum 20 , a charging device 21 , a developing device 22 , a primary transfer roller 23 and a cleaning device 24 . The photosensitive drum 20 rotates around its axis while contacting the lower side of the intermediate transfer belt 14 . The charging device 21, the developing device 22, the primary transfer roller 23, and the cleaning device 24 are arranged around the photosensitive drum 20 in order of the image forming process. The primary transfer roller 23 faces the photosensitive drum 20 from above with the intermediate transfer belt 14 interposed therebetween.

<Conveyor>
As shown in FIGS. 1 and 2, the transport device 13 has a transport main body 30, a registration roller pair 31, a secondary transfer roller 32, and a plurality of transport roller pairs 33-35.

The conveying body portion 30 is provided between the conveying path 6 and the reverse conveying path 7, constitutes a part of the conveying path 6 and the reverse conveying path 7, and has a function of guiding the conveyed sheet S. there is An opening/closing cover 17 is provided on the device main body 2 so as to be able to be opened and closed. The opening/closing cover 17 is rotatably provided, for example, about one rear side thereof (not shown). The opening/closing cover 17 constitutes the right side surface of the apparatus main body 2 in a closed state, and constitutes the reverse conveying path 7 between itself and the conveying main body section 30 . By opening the opening/closing cover 17, the sheet S jammed in the transport path 6 or the reversing transport path 7 can be removed (jam processing can be performed). In addition, the opening/closing cover 17 may be provided so as to be rotatable about one lower side, for example.

The registration roller pair 31 is provided downstream of the confluence of the reversing transport path 7 and upstream of the secondary transfer roller 32 . The registration roller pair 31 temporarily blocks the sheet S conveyed on the conveying path 6 to correct the inclination of the sheet S (skew correction). The secondary transfer roller 32 is supported by the conveying main body 30 and contacts the right end of the intermediate transfer belt 14 to form a transfer nip N1. The conveying roller pairs 33 to 35 are arranged at appropriate positions on the reverse conveying path 7 . One roller of the pair of transport rollers 34 and 35 is supported by the transport main body 30 and the other roller is supported by the opening/closing cover 17 .

[Image formation processing]
Here, the operation of the image forming apparatus 1 will be described. For example, a control unit (not shown) executes image forming processing as follows based on image data input from an external terminal.

The charging device 21 charges the surface of the photosensitive drum 20 . The optical scanning device 16 exposes the photosensitive drum 20 to form an electrostatic latent image corresponding to image data on the surface of the photosensitive drum 20 . The developing device 22 uses the toner supplied from the toner container 5 to develop the electrostatic latent image on the photosensitive drum 20 into a toner image. The four color toner images carried on the four photosensitive drums 20 are sequentially primary-transferred onto the rotating intermediate transfer belt 14 by the primary transfer rollers 23 to which a primary transfer bias is applied. The intermediate transfer belt 14 rotates and carries a full-color toner image in which four color toner images are superimposed. The cleaning device 24 removes toner remaining on the surface of the photosensitive drum 20 after the primary transfer.

The paper feeder 10 takes out the paper S accommodated in the cassette 3 and sends it out to the transport path 6 . The registration roller pair 31 feeds the skew-corrected sheet S downstream. A secondary transfer roller 32 to which a secondary transfer bias is applied secondarily transfers the toner image on the intermediate transfer belt 14 onto the surface of the sheet S passing through the transfer nip N1. The fixing device 12 heats and presses the toner image transferred to the paper S to thermally fix it on the paper S. As shown in FIG. In the case of single-sided printing, the sheet S on which the toner image is fixed (on which the image is formed) is discharged to the discharge tray 4 .

When double-sided printing is performed, the sheet S that has passed through the fixing device 12 is switched back at the downstream end of the transport path 6 and sent to the reverse transport path 7 . A plurality of transport roller pairs 33 to 35 transport the sheet S along the reverse transport path 7 , and the sheet S enters the transport path 6 again from the reverse transport path 7 . Then, an image is formed on the back side of the sheet S in the same procedure as that for single-sided printing described above.

[Fixing device]
Next, the fixing device 12 will be described with reference to FIGS. 2 to 4. FIG. FIG. 3 is a perspective view showing the fixing device 12. FIG. FIG. 4 is a plan view showing the rear portion of the fixing device 12. As shown in FIG.

As shown in FIGS. 2 and 3 , the fixing device 12 has a fixing belt 25 , a pressure roller 26 , a heat generating section 27 , a pair of fixing conveying rollers 40 and a drive transmission device 50 .

<Fixing belt>
The fixing belt 25, which is an example of the fixing member, is made of a material in which metal and synthetic resin are laminated, and is formed in a substantially cylindrical shape elongated in the front-rear direction. As shown in FIG. 2, inside the fixing belt 25, a support member 25A, a pressing pad 25B, and a belt guide 25C are provided. The support member 25A passes through the fixing belt 25 in the axial direction, and both ends thereof are supported by the fixing frame 36 (see FIG. 1). The pressure pad 25B is made of synthetic resin having heat resistance, and is fixed to the support member 25A so as to face the pressure roller 26 with the fixing belt 25 interposed therebetween. The belt guide 25C is made of metal and is formed in a substantially semi-cylindrical shape elongated in the axial direction. The belt guide 25C is fixed to the support member 25A on the opposite side of the pressing pad 25B, contacts the inner surface of the fixing belt 25, and maintains the fixing belt 25 in a substantially cylindrical shape.

As shown in FIG. 3, the fixing belt 25 is rotatably supported by a support member 25A through a pair of caps 25D attached to both front and rear ends. A gear (not shown) is integrally formed on the cap 25D, and the fixing belt 25 is rotated by receiving a driving force of a motor (not shown) connected to the gear.

<Pressure roller>
As shown in FIG. 2 , the pressure roller 26 , which is an example of a pressure member, is formed in a substantially cylindrical shape elongated in the front-rear direction, and is arranged on the right side of the fixing belt 25 . The pressure roller 26 is formed, for example, by laminating an elastic layer 26B made of synthetic resin on the outer peripheral surface of a metal core 26A. Both axial ends of the pressure roller 26 (core bar 26A) are rotatably supported by a pair of movable frames (not shown). The movable frame is supported by a fixing frame 36 (see FIG. 1) so as to be able to swing in the horizontal direction, and is connected to a pressure adjusting section (not shown) including a spring, an eccentric cam, and the like.

When the pressure adjustment unit rotates the movable frame toward the fixing belt 25 , the pressure roller 26 is pressed against the fixing belt 25 to form a pressure area N<b>2 between itself and the fixing belt 25 . The pressure roller 26 rotates following the fixing belt 25 while the pressure area N2 is pressed. On the other hand, when the pressure adjusting section rotates the movable frame in the direction away from the fixing belt 25, the pressing roller 26 is released from the fixing belt 25 and forms a pressure-reduced pressure area N2. Note that the fixing belt 25 is pressed by the pressure roller 26 and deformed in a state where the pressure area N2 is formed. The pressurized region N2 refers to a region from the upstream position where the pressure is 0 Pa to the downstream position where the pressure becomes 0 Pa again via the maximum pressure position.

<Exothermic part>
The heat generating portion 27 is arranged on the left side of the fixing belt 25 with a gap therebetween. The heating unit 27 is an induction heating heater that generates a magnetic field to cause the fixing belt 25 to generate heat by itself. The belt guide 25</b>C absorbs leakage magnetic flux that has passed through the fixing belt 25 and generates heat by itself, thereby assisting the heating of the fixing belt 25 . Although the induction heating type heat generating portion 27 is arranged outside the fixing belt 25 as a heat source, instead of this, a halogen heater, a carbon heater, or the like may be arranged inside the fixing belt 25 .

<Pair of Fixing and Conveying Rollers>
As shown in FIG. 2, the fixing transport roller pair 40 is arranged downstream (upper) than the pressure roller 26 and the like (pressure area N2). As shown in FIGS. 2 and 4 , the fixing/conveying roller pair 40 has a discharge roller 41 and a driven roller 45 .

(Ejection roller)
The ejection roller 41 is supported by a fixing cover 37 provided above the fixing frame 36 . The discharge roller 41 is formed, for example, by laminating a roller body 43 made of synthetic resin on the outer peripheral surface of a transmission shaft 42 made of metal. Both front and rear sides of the transmission shaft 42 are rotatably supported by the fixing cover 37 via bearing portions 66 (see FIG. 6A, which will be described later). The roller body 43 is fixed to the transmission shaft 42 and rotates around the axis together with the transmission shaft 42 .

(driven roller)
The driven roller 45 is supported above the fixing frame 36 . The driven roller 45 is formed, for example, by laminating a synthetic resin roller body 47 on the outer peripheral surface of a metal driven shaft 46 . Both front and rear ends of the driven shaft 46 are rotatably supported by the fixing frame 36 via bearings (not shown). The roller body 47 is fixed to the driven shaft 46 and rotates together with the driven shaft 46 around the axis.

(fixing cover)
As shown in FIG. 2, the fixing cover 37 is swingably supported above the fixing frame 36 via a pair of front and rear support shafts 37A. When the opening/closing cover 17 is opened, the fixing cover 37 has a separation position that separates the discharge roller 41 from the driven roller 45 in the opening direction (right direction in FIG. 2) and a separation position that separates the discharge roller 41 from the driven roller 45 in the closing direction (left direction in FIG. 2). ) to bring it into close contact with the driven roller 45 .

<Drive transmission device>
As shown in FIG. 4 , the drive transmission device 50 is arranged behind the pair of fixing/conveying rollers 40 . As shown in FIGS. 3 and 4, the drive transmission device 50 includes a drive gear 51, a transmission gear 53, and an urging member .

(drive gear)
The drive gear 51 is a so-called spur gear (involute gear) that rotates about a drive shaft 52 and is arranged in the upper rear portion of the fixing frame 36 . The drive shaft 52 (rear end) is non-rotatably supported (fixed) by a support member 38A erected on the upper rear side (one side in the axial direction) of the fixing frame 36 . The drive gear 51 is rotatably supported by the drive shaft 52 at a position facing (the front surface of) the support member 38A. A drive motor 28 (drive source) is connected to the drive gear 51 via another gear train (not shown) (see FIG. 3). The driving gear 51 receives driving force from the driving motor 28 and rotates around its axis.

A portion of the drive shaft 52 that rotatably supports the drive gear 51 has a circular cross section, and a portion of the drive shaft 52 that protrudes forward from the drive gear 51 (hereinafter also referred to as a “D-cut portion”) is substantially D-shaped. (see FIG. 6A to be described later). At the top of the fixing frame 36, a regulating member 38B is erected in front of the support member 38A (the other side in the axial direction). The regulating member 38B is erected to face the front of the supporting member 38A with a space for arranging the drive gear 51 interposed therebetween.

(transmission gear)
The transmission gear 53 is a so-called spur gear (involute gear) that rotates about the transmission shaft 42 and meshes with the drive gear 51 from the right side. The transmission shaft 42 of the discharge roller 41 extends rearward from the roller body 43 , and the transmission gear 53 is non-rotatably supported (fixed) on the rear portion of the transmission shaft 42 . In other words, the transmission gear 53 is supported by the fixing cover 37 via the transmission shaft 42 . The fixing cover 37 moves (rotates) in the opening direction (rightward direction in FIGS. 3 and 4) to disengage the transmission gear 53 from the drive gear 51, and closes in the closing direction (leftward direction in FIGS. 3 and 4). direction) to mesh the transmission gear 53 with the driving gear 51 . The transmission gear 53 meshes with the drive gear 51 and rotates around the axis as the drive gear 51 rotates.

(biasing member)
As shown in FIG. 4 , the biasing member 54 is, for example, a compression coil spring and is provided at the upper rear portion of the fixing cover 37 . In a state in which the fixing cover 37 is arranged at the closed position and the opening/closing cover 17 is closed (hereinafter also simply referred to as the “closed state”), the biasing member 54 is pushed leftward and compressed by the opening/closing cover 17 . . The biasing member 54 compressed in this manner biases the fixing cover 37 in the closing direction (leftward). As a result, the discharge roller 41 supported by the fixing cover 37 via the transmission shaft 42 is pressed against the right side of the driven roller 45 to form the discharge nip N3 (see FIG. 2). Further, the transmission gear 53 supported by the fixing cover 37 via the transmission shaft 42 meshes firmly with the driving gear 51 .

[Fixing process]
Here, the operation of the fixing device 12 will be described. The control unit executes the fixing process while appropriately controlling the fixing device 12 during the image forming process described above.

Specifically, the heat generating section 27 heats the fixing belt 25 . The fixing belt 25 heats the toner image on the sheet S passing through the pressure area N2 while rotating about its axis. The pressure roller 26 presses the toner on the paper S passing through the pressure area N2 while rotating about its axis. The toner image on the sheet S is melted and fixed to the sheet S while the sheet S passes through the pressure area N2.

Further, the drive transmission device 50 transmits the driving force (rotational force) of the drive motor 28 to the transmission shaft 42 (discharge roller 41). The discharge roller 41 rotates about the transmission shaft 42 by the driving force of the drive motor 28 , and the driven roller 45 rotates about the driven shaft 46 following the discharge roller 41 . The pair of fixing and conveying rollers 40 (discharge roller 41 and driven roller 45) sandwiches the sheet S that has passed through the pressure area N2 and conveys it by rotating around its axis. If the sheet S is jammed in the pressure area N2 or the discharge nip N3, the jammed sheet S can be removed (jammed) by rotating the fixing cover 37 from the closed position to the separated position. can be done. Further, the pressure adjusting section described above is configured to be interlocked with the fixing cover 37. When the fixing cover 37 is rotated from the closed position to the separated position, the movable frame rotates away from the fixing belt 25, The pressurized area N2 is decompressed (not shown). On the contrary, when the fixing cover 37 is rotated from the separated position to the closed position, the movable frame rotates in the direction of approaching the fixing belt 25, and the pressure area N2 is pressed (not shown). .

By the way, in order to properly transmit the driving force of the drive motor 28 to the discharge roller 41, it is necessary to maintain a defined interaxial distance D between the drive gear 51 and the transmission gear 53. FIG. For example, if the shaft-to-shaft distance D is longer than the prescribed value, tooth jumping occurs and normal transmission of driving force cannot be ensured. Further, for example, if the distance D between the shafts is shorter than the prescribed distance D, both the gears 51 and 53 cannot rotate normally. Therefore, the drive transmission device 50 according to the present embodiment has a structure for keeping the distance D between the shafts of the driving gear 51 and the transmission gear 53 constant.

4, 5, 6A and 6B, the structure for keeping the distance D between the axes constant will be specifically described. FIG. 5 is a perspective view showing the drive contact member 60. FIG. 6A is a front view showing the drive transmission device 50, and FIG. 6B is a front view showing a part of the drive transmission device 50 in an enlarged manner.
6A and 6B, the addendum circles of the driving gear 51 and the transmission gear 53 are indicated by solid lines or dashed lines, and the pitch circles P1 and P2 of the driving gear 51 and the transmission gear 53 are indicated by dashed lines. The pitch circles P1 and P2 are the points of intersection of the trajectory of the contact points of the tooth surfaces of the drive gear 51 and the transmission gear 53 and the line segment connecting the rotation centers of the gears 51 and 53. It refers to a circle that passes through (pitch point P0) and has the same axis as both gears 51 and 53 .

As shown in FIG. 4 , the drive transmission device 50 further includes a drive contact member 60 and a transmission contact member 65 .

(drive contact member)
The drive contact member 60 is made of, for example, a resin material or a metal material, and is non-rotatably provided on the same axis as the drive shaft 52 . The drive contact member 60 is arranged in front of the drive gear 51 (see FIG. 4). As shown in FIG. 5 , the drive contact member 60 has a tubular sleeve portion 61 and a projecting portion 62 projecting from the sleeve portion 61 .

An insertion hole 61A is formed through the sleeve portion 61 in the front-rear direction. The rear end portion of the insertion hole 61A is formed in a substantially circular shape, and the portion of the insertion hole 61A excluding the rear end portion is formed in a substantially D shape. The drive contact member 60 is non-rotatably supported (fixed) on the drive shaft 52 by inserting the D cut portion of the drive shaft 52 through the insertion hole 61A of the sleeve portion 61 . The drive contact member 60 is fixed to the drive shaft 52 between the regulating member 38B and the drive gear 51 (see FIG. 4).

The projecting portion 62 is integrally formed from the right side of the sleeve portion 61 to the lower side thereof. A drive contact surface 63 curved concentrically with the drive gear 51 is formed on the right side surface of the projecting portion 62 . As shown in FIG. 6A, the drive contact surface 63 has a curved surface that matches the pitch circle P1 of the drive gear 51 when viewed from the front (axial direction). In other words, the drive contact surface 63 has the same curvature as the pitch circle P1.

As shown in FIG. 5, an engagement recess 62A is formed in a substantially triangular notch on the lower front side of the projecting portion 62. As shown in FIG. The driving contact member 60 is sandwiched between the restricting member 38B and the driving gear 51 in a state in which the driving shaft 52 passes through the driving contact member 60, and the right end of the restricting member 38B is fitted in the engaging recess 62A (see FIG. 4). reference). This restricts the movement of the drive gear 51 in the front-rear direction (axial direction).

(Transmission contact member)
The transmission contact member 65 is made of, for example, a resin material or a metal material, and is non-rotatably provided on the same axis as the transmission shaft 42 . The transmission contact member 65 is arranged on the front side of the transmission gear 53 (see FIG. 4). As shown in FIG. 6A, the transmission contact member 65 is formed in a substantially U-shape with the left side opened when viewed from the front, and is fitted into the fitting recess 37B formed in the fixing cover 37 (fixed). is being used). The fitting recess 37</b>B is formed at the left end of the fixing cover 37 and forward of the transmission gear 53 . A bearing portion 66 is fitted (fixed) in the U-shaped portion of the transmission contact member 65 , and the transmission shaft 42 is inserted through the bearing portion 66 and rotatably supported by the transmission contact member 65 via the bearing portion 66 .

A transmission contact surface 67 curved concentrically with the transmission gear 53 is formed on the upper left side surface of the transmission contact member 65 . The transmission contact surface 67 has a curved surface that matches the pitch circle P2 of the transmission gear 53 . In other words, the transmission contact surface 67 has the same curvature as the pitch circle P2.

It should be noted that both the contact surfaces 63 and 67 matching the pitch circles P1 and P2 (having the same curvature) does not mean strictly matching (identical), but allowing for manufacturing errors. Meaning.

As shown in FIGS. 6A and 6B, in the closed state, the transmission contact member 65 is positioned to bring the transmission contact surface 67 into contact with the drive contact surface 63 . In the closed state, the biasing member 54 biases the transmission shaft 42 toward the drive shaft 52 via the fixing cover 37 (see arrow F shown in FIG. 6A), and the transmission contact surface 67 and the drive contact surface 63 are separated. are kept in contact with each other. The transmission contact surface 67 and the drive contact surface 63 are in contact with each other at one point when viewed from the front (approximately one line when viewed from the top). This contact portion (contact point) substantially coincides with the pitch point P0 of both gears 51 and 53 when viewed from the front.

In the drive transmission device 50 according to the present embodiment described above, the transmission shaft 42 is biased toward the drive shaft 52 through the fixing cover 37, and the curved transmission contact surface 67 and the drive contact surface 63 partially contact each other. was maintained in pristine condition. According to this configuration, it is possible to restrict the drive gear 51 and the transmission gear 53 from approaching or separating from each other. Further, since the drive contact member 60 and the transmission contact member 65 are provided on both shafts 42 and 52, it is possible to form separate parts with high precision to support both the contact members 60 and 65 and to position them accurately. Therefore, the manufacturing cost of the drive transmission device 50 can be reduced. As a result, the distance D between the axes of the two gears 51 and 53 that mesh with each other can be easily kept constant. Further, since the drive contact member 60 and the transmission contact member 65 do not rotate, it is possible to prevent the transmission contact surface 67 and the drive contact surface 63 from rubbing and being worn. Thereby, the center distance D can be kept constant over a long period of time.

In addition, in the drive transmission device 50 according to the present embodiment, the contact surfaces 63 and 67 are formed on the pitch circles P1 and P2 of the gears 51 and 53, so the drive contact surface 63 and the transmission contact surface 67 are located in front ( axial direction), contact approximately at the pitch point P0 (see FIGS. 6A and 6B). According to this configuration, the force component Fc (see FIG. 6B) of the biasing force F of the biasing member 54 can be directed in the normal direction of the contact portion between the contact surfaces 63 and 67 . As a result, the force Fc is applied in the direction orthogonal to the contact portions of the contact surfaces 63 and 67, so that the state in which the contact surfaces 63 and 67 are in contact with each other can be stabilized.

Further, according to the drive transmission device 50 according to the present embodiment, the drive contact member 60 is fixed to the drive shaft 52 between the regulating member 38B and the drive gear 51. It can also be used as a retainer. As a result, the number of parts can be reduced and the manufacturing cost of the drive transmission device 50 can be reduced as compared with the case where the drive gear 51 is provided with a separate part.

By the way, if the drive shaft 52 and the transmission shaft 42 are supported by one support plate (not shown), the positions of both shafts 42, 52 are determined, so the distance D between the shafts is also kept constant. However, if both shafts 42 and 52 are supported by one support plate, the gears 51 and 53 cannot be disengaged from each other. Therefore, in a structure such as the fixing device 12 described above, in which it is necessary to open the fixing cover 37 and disengage the gears 51 and 53 in order to clear a jam, the two shafts 42 and 52 are attached to one supporting plate. Supporting structures cannot be adopted. On the other hand, according to the fixing device 12 according to the present embodiment, even if the transmission shaft 42 is configured to move together with the fixing cover 37, the contact surfaces 63 and 67 are separated by arranging the fixing cover 37 at the closed position. The distance D between the axes of the gears 51 and 53 that contact and mesh with each other can be made constant.

In the drive transmission device 50 according to this embodiment, the drive contact surface 63 of the drive contact member 60 has the same curvature as the pitch circle P1 of the drive gear 51, but the present invention is not limited to this. For example, the driving contact surface 63 may be a curved surface having a curvature larger or smaller than the curvature of the pitch circle P1 (not shown). Similarly, the transmission contact surface 67 of the transmission contact member 65 may be a curved surface having a curvature larger or smaller than the curvature of the pitch circle P2 (not shown). In other words, both contact surfaces 63 and 67 may be formed substantially along the pitch circles P1 and P2 of the gears 51 and 53, respectively.

In addition, in the drive transmission device 50 according to the present embodiment, the drive contact member 60 is a separate member from the fixing frame 36 and the regulating member 38B. (not shown). Similarly, for example, the transmission contact member 65 may be integrally formed with the fixing cover 37 (not shown).

Also, in the drive transmission device 50 according to the present embodiment, the drive gear 51 is rotatably supported by the drive shaft 52 , but the drive gear 51 may be fixed to the drive shaft 52 . In this case, the drive contact member 60 is arranged on the same axis as the drive shaft 52, but is preferably fixed to the fixing frame 36 or the like without contacting the drive shaft 52 (not shown).

Further, in the drive transmission device 50 according to this embodiment, the biasing member 54 is a compression coil spring, but the present invention is not limited to this. For example, the biasing member 54 may be an elastic body such as rubber, or may be a tension spring that biases the fixing cover 37 toward the closed position. Alternatively, a torsion coil spring may be provided on the support shaft 37A. Further, in the drive transmission device 50 according to the present embodiment, the biasing member 54 biases the transmission shaft 42 toward the drive shaft 52 via the fixing cover 37, but the invention is not limited to this. For example, biasing member 54 may be provided to bias drive shaft 52 toward transmission shaft 42 (not shown).

Further, although the drive transmission device 50 according to this embodiment is provided for the drive transmission to the ejection roller 41 of the fixing device 12, the present invention is not limited to this. The drive transmission device 50 can be applied as long as it has a structure in which two or more gears are used to transmit the drive force to the rotating body. Further, when the transmission shaft 42 is not used as a rotating shaft of another member, the transmission gear 53 may be rotatably supported by the transmission shaft 42 without being fixed to the transmission shaft 42 .

Further, in the fixing device 12 according to the present embodiment, the ejection roller 41 and the driven roller 45 constitute the pair of fixing and conveying rollers 40 . A configuration may be adopted in which the sheet S contacts a sliding platen (not shown).

Further, in the fixing device 12 according to the present embodiment, the fixing belt 25 is used as an example of the fixing member, but the fixing belt 25 is not limited to this, and a roller member similar to the pressure roller 26 may be used (not shown). figure). Further, although the pressure roller 26 is used as an example of the pressure member, it is not limited to this, and a belt member similar to the fixing belt 25 may be used (not shown).

Further, although the image forming apparatus 1 according to the present embodiment is a color printer, the present invention is not limited to this, and may be applied to, for example, a monochrome printer, copier, facsimile machine, multifunction machine, or the like.

It should be noted that the description of the above embodiment shows one aspect of the drive transmission device, the fixing device, and the image forming apparatus according to the present invention, and the technical scope of the present invention is not limited to the above embodiment. . The present invention may be changed, replaced, and modified in various ways without departing from the spirit of the technical idea, and the claims include all embodiments that can be included within the scope of the technical idea.

1 image forming apparatus 12 fixing device 25 fixing belt (fixing member)
26 pressure roller (pressure member)
28 drive motor (drive source)
37 fixing cover 38A support member 38B regulation member 41 discharge roller 42 transmission shaft 50 drive transmission device 51 drive gear 52 drive shaft 53 transmission gear 54 biasing member 60 drive contact member 63 drive contact surface 65 transmission contact member 67 transmission contact surface N2 addition Pressure area P1, P2 Pitch circle S Paper (medium)

Claims (5)

a drive gear that rotates around a drive shaft by receiving a drive force from a drive source;
a transmission gear that meshes with the drive gear and rotates around a transmission shaft as the drive gear rotates;
a drive contact member having a drive contact surface curved concentrically with the drive gear and non-rotatably provided on the same axis as the drive shaft;
a transmission contact member having a transmission contact surface curved concentrically with the transmission gear, and non-rotatably provided on the same axis as the transmission shaft at a position where the transmission contact surface contacts the drive contact surface;
One of the drive shaft and the transmission shaft is biased toward the other of the drive shaft and the transmission shaft to maintain the transmission contact surface and the drive contact surface in contact with each other. A drive transmission device comprising: a force member; the drive contact surface has a curved surface that matches the pitch circle of the drive gear;
2. A drive transmission device according to claim 1, wherein said transmission contact surface has a curved surface that matches the pitch circle of said transmission gear. The drive shaft is non-rotatably supported by a support member provided on one side in the axial direction,
the drive gear is rotatably supported by the drive shaft at a position facing the support member;
3. The drive transmission device according to claim 1, wherein said drive contact member is fixed to said drive shaft between said drive gear and a regulating member provided on the other side in the axial direction. a drive transmission device according to claim 3;
a fixing member that heats the toner image on the medium while rotating about its axis;
a pressure member that forms a pressure region between itself and the fixing member while rotating about an axis and presses the toner on the medium passing through the pressure region;
a discharge roller that rotates about the transmission shaft and conveys the medium that has passed through the pressure area;
The transmission shaft to which the transmission gear is fixed is rotatably supported around the axis, moves in the opening direction to release the meshing of the transmission gear with the driving gear, and moves in the closing direction to engage the driving gear. a fixing cover that meshes with the transmission gear,
The fixing device, wherein the biasing member biases the fixing cover toward the closing direction. An image forming apparatus comprising the fixing device according to claim 4 .

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