WO2013132572A1

WO2013132572A1 - Drive transmission unit

Info

Publication number: WO2013132572A1
Application number: PCT/JP2012/055529
Authority: WO
Inventors: 雄一田邉
Original assignee: キヤノン株式会社
Priority date: 2012-03-05
Filing date: 2012-03-05
Publication date: 2013-09-12

Abstract

The purpose of the invention is to provide a drive transmission unit, which has a small number of parts and a simple configuration and which is capable of limiting the sounds of impact between the input part and the output part in the coupling section. A drive transmission unit in which, when the input member is rotating in the forward direction, the output member receives the driving force from the input member via an intermediate member and rotates. The intermediate member is provided with a first receiving section, which receives a forward rotation driving force that has been input to the input member and has been converted to a force in the direction for moving the intermediate member along the direction of the rotation axis to the position for transmitting the driving force to the output member, and a second receiving section, which receives a reverse rotation driving force that has been input to the input member and has been converted to a force in the direction for withdrawing the intermediate member along the direction of the rotation axis from the position for driving the output member.

Description

Drive transmission unit

The present invention relates to a drive transmission unit that transmits or blocks a driving force input from a driving source to a driven body in accordance with the rotation direction.

In various apparatuses, it is desired that a plurality of rotating bodies (driven bodies) be rotationally driven by a smaller number of motors (driving sources). For example, in an electrophotographic image forming apparatus, it is desired to rotate a plurality of developing sleeves with a single motor, or to rotate both a developing sleeve and a photoreceptor with a single motor.

Here, even in a configuration in which a plurality of rotating bodies are rotated by one motor, there is a demand for selectively rotating a certain rotating body. For example, there is a demand to selectively rotate only the photoconductor while rotating both the developing sleeve and the photoconductor with one motor.

In response to this demand, a configuration has been devised in which a one-way unit is arranged in a drive transmission path from a motor to a rotating body and the rotating body is selectively driven by rotating the motor forward and backward (Patent Document 1).

Here, since a general one-way unit has a plurality of balls and needles arranged in the circumferential direction, the number of parts is large and the structure is complicated, so that a small one is expensive. On the other hand, Patent Document 2 proposes a drive transmission unit (one-way unit) having a relatively small number of parts and a simple configuration. Specifically, a configuration is disclosed that includes an input gear, an output gear that includes a ratchet portion, and a spring that is provided on the output gear surface of the input gear and contacts the ratchet portion of the output gear.

JP-A-6-118784 JP 2005-163826 A

Here, when the drive transmission unit described in Patent Document 2 is arranged in the drive transmission path from the motor to the rotating body and the rotating body is selectively rotated, the following problems occur. Specifically, when a drive in a direction (reverse rotation) in which the driving force is not transmitted to the output gear (output member) is input to the input gear (input member), there is a problem that periodic impact noise is generated. .

When a driving force in the positive direction is input to the input gear disclosed in Patent Document 2, a pawl constituted by a spring bites into the rotation suppression surface of the ratchet portion provided in the output gear, and the driving input to the input gear is performed. It is transmitted to the output gear. On the contrary, when a driving force in the reverse direction is input to the input gear, the pawl formed by the spring rides over the slope of the ratchet portion, so that the driving force is not transmitted to the output gear.

Here, since the claws that have crossed the slope of the ratchet are composed of springs, the claws that have overcome the slope will be restored to their original posture by their own elasticity. Therefore, when the driving force in the reverse rotation direction is continuously input to the input gear, the claw repeats the operation of overcoming the slope and restoring. Each time the claw gets over the slope, the claw (spring) collides with the output gear due to the restoring force, resulting in a periodic impact sound.

Therefore, the purpose of this case is to reduce the sound when the drive is cut off while realizing one-way transmission with a relatively small number of parts.

Therefore, the drive transmission unit of the present invention includes an “input member that can be rotated in both forward and reverse directions by receiving a driving force input from a drive source, an intermediate member that is movable in the rotational axis direction of the input member, and the input member. An output member that rotates by receiving a driving force from the input member via the intermediate member when the input member rotates in the forward direction, and the intermediate member is input to the input member. A first receiving portion that receives a force converted to a force in a direction to move the rotational driving force in the positive direction along the rotational axis direction to a position where the driving force is transmitted to the output member, and is input to the input member. A second receiving portion that receives a force converted from a position where the rotational driving force in the reverse direction is driven to the output member along the rotational axis direction to a force in the retracting direction.

This makes it possible to reduce the noise when the drive is cut off, while achieving one-way transmission with a relatively small number of parts.

1 is a cross-sectional view schematically illustrating an image forming apparatus according to an embodiment. 1 is a schematic diagram of a fixing device and a driving path according to an embodiment. FIG. 6 is a diagram for explaining a contact / separation operation of the fixing device according to the embodiment. It is an external view of the drive transmission unit which concerns on an Example. It is the perspective view and sectional drawing of the drive transmission unit which concern on an Example. It is detail drawing of each element which comprises the drive transmission unit which concerns on an Example. It is a figure for demonstrating each state of the drive transmission unit which concerns on an Example. It is a figure for demonstrating the operation | movement at the time of forward rotation of the drive transmission unit which concerns on an Example. It is a figure for demonstrating the operation | movement at the time of reverse rotation of the drive transmission unit which concerns on an Example. It is a figure for demonstrating the structure of the drive transmission unit which concerns on an Example. It is a figure for demonstrating the schematic structure of a comparative example, and the generation principle of a periodic collision sound.

Hereinafter, the drive transmission unit and the image forming apparatus according to the embodiment will be described with reference to the drawings. The dimensions, materials, shapes, and relative arrangements of the components described in the embodiments should be changed as appropriate according to the configuration of the apparatus to which the idea is applied and various conditions. The present invention is not intended to be limited to the following embodiments.

Hereinafter, the outline of the image forming apparatus including the drive transmission unit will be described, and then the configuration of the drive transmission unit will be described in detail.

§1. {Explanation on schematic configuration of image forming apparatus}
The schematic configuration of the image forming apparatus according to the present embodiment will be briefly described below.

■ (About the overall configuration of the entire device)
FIG. 1A is a diagram for explaining a schematic configuration of a printer 1 as an image forming apparatus. The printer 1 as an image forming apparatus includes first to fourth stations S (Bk to Y), and forms images with different toners on the respective photosensitive drums. Each station is substantially the same except for the type (spectral characteristics) of the toner that develops the electrostatic image formed on the photosensitive drum, and therefore, one station (Bk) will be described as a representative.

The station S (Bk) as an image forming unit includes a photosensitive drum as an image carrier and a charging device for charging the photosensitive drum. The photosensitive drum charged by the charging device is exposed from the laser scanner LS, and an electrostatic image is formed on the photosensitive drum. The electrostatic image formed on the photosensitive drum is developed into a toner image with black toner accommodated in a developing device. The toner image developed on the photosensitive drum is transferred to an intermediate transfer belt ITB as an intermediate transfer member. A charging device, a developing device, and the like that are involved in forming a toner image on the photosensitive drum are referred to as an image forming unit.

The toner images transferred in the order of yellow (Y), magenta (M), cyan (C), and black (Bk) from the photosensitive drum provided in each station S are superimposed on the intermediate transfer belt. The superimposed toner images are transferred to the recording material conveyed from the cassette CA in the secondary transfer portion T.

The toner image transferred onto the recording material comes into contact with the toner and is fixed to the recording material by a fixing device F that heats and melts the toner and heat-fixes it on the recording material. Discharged.

■ (Fixing device configuration)
Next, the configuration of the fixing device F of this embodiment will be described in detail. FIG. 1B is a schematic cross-sectional view of the fixing device F. The fixing device F includes a heating film 1f as a film-shaped (belt-shaped) heating member that is heated in contact with unfixed toner. The heating film 1 f forms a nip portion for heating the pressure roller 4 f as a pressure member and the recording material P.

A release layer such as a fluororesin or an elastic layer is provided on the surface of the heating film 1f and the pressure roller 4f in order to realize preferable fixing conditions. Inside the heating film 1f, a support stay 3f and a plate-like heating element (ceramic heater) 2f that stably form a heating nip are disposed. The support stay 3f and the pressure roller 4f are pressed by a spring 3d at about 300N.

FIG. 2A is a perspective view of a driving train D for rotating and driving the fixing device F and the pressure roller 4f of this embodiment and for contacting and separating the heating film 1f and the pressure roller 4f. The rotational driving force transmitted from the motor M is transmitted to the pressure roller via the drive train D (forward rotation).

Here, it is preferable to separate the heating film 1f and the pressure roller 4f when a jam occurs. For this reason, the fixing device F of this embodiment includes a mechanism that enables the heating film 1f and the pressure roller 4f to contact and separate. In this embodiment, since the member on the side in contact with the unfixed toner is a film and is difficult to rotate, the pressure roller 4f is rotated and the heating film 1f can be moved in the contact / separation direction. Adopted.

§2. {About fixing device drive and contact / separation mechanism}
Subsequently, one drive source (motor) is rotated in the forward direction at the time of image formation to rotate the pressure roller 4f, and is reversely rotated even when a jam occurs, to release the pressure between the heating film 1f and the pressure roller 4f. The transmission path will be described. First, the outline of the connection relationship will be described with reference to the schematic diagram of the drive transmission path. Next, operations and postures of the heating film 1f and the pressure roller 4f during forward and reverse rotation will be described using external views.

■ (About drive transmission path)
FIG. 2B is a schematic diagram for explaining the drive transmission path. The controller CO as a control device controls the motor M so as to rotate forward during image formation and reverse during jamming. Specifically, the controller CO reversely controls the motor M when a sensor (not shown) that detects a jam of the fixing device F detects the jam. The rotation direction of each element when the motor rotates in the forward direction regardless of the rotation direction of each element is referred to as the forward rotation direction, and the rotation direction of each element when the motor rotates in the reverse direction is referred to as the reverse rotation direction.

As shown in FIG. 2B, the drive train D to which the driving force is transmitted from the motor M includes a one-way unit 100 as a drive transmission device (drive transmission unit), a peristaltic gear, in addition to the transmission gear that transmits the drive. 1d and a pressure release cam 2d. When the motor M rotates in the forward direction, the one-way unit 100 transmits driving force to both the first path and the second path. That is, the one-way unit 100 transmits the pressure roller 4f and the swinging gear 1d via the rotational driving force in the positive direction. Further, when the motor M rotates in the reverse direction, the one-way unit 100 transmits the driving force only to the second path without transmitting the driving force to the first path.

The oscillating gear 1d provided in the drive train D is configured to oscillate when forward rotation is transmitted and to block the downstream drive transmission, and to transmit the driving force downstream when the reverse rotation is transmitted. Has been. A pressure release cam 2d for separating the heating film 1f from the pressure roller 4f is provided on the downstream side along the drive transmission forward direction of the swing gear 1d.

In this way, by configuring the drive path, while the pressure roller 4f is rotated forward during image formation with one motor, a reverse driving force is transmitted to the pressure release cam 2d during jam detection and heating is performed. The film 1f and the pressure roller 4d can be separated.

■ (Operation of the fixing device during forward rotation and reverse rotation)
Next, the posture and operation of the fixing device F when the motor M is operated by switching the rotation in both forward and reverse directions will be described with reference to FIG.

A: (For forward rotation)
FIG. 3A is an external view for explaining the posture and operation of the fixing device F when the motor M is rotated in the forward direction. When forward rotation drive is transmitted from the motor M, the one-way unit 100 rotates the pressure roller 4f. On the other hand, the swing gear 1d is misaligned due to the long hole supporting the shaft, and the downstream transmission gear is non-rotating. Therefore, the pressure release cam 2d is not decentered, and the heating film 1f and the pressure roller 4f are brought into contact with each other and pressed by the spring 3d.

B: (during reverse rotation)
FIG. 3B is an external view for explaining the posture and operation of the fixing device F when the motor M is rotated in the reverse direction. When the reverse rotation drive is transmitted from the motor M, the one-way unit 100 does not transmit the driving force to the pressure roller 4f on the output gear side (downstream side). Therefore, the pressure roller 4f is in a stopped state. On the other hand, when the reverse rotation is transmitted to the swing gear 1d, the shaft moves through the elongated hole portion and transmits the driving force to the downstream transmission gear. As a result, the pressure release cam 2d is eccentric, and the heating film 1f and the pressure roller 4f are in a separated state. The pressure release cam 2d moves the arm that supports the heating film 1d with a force that exceeds the urging force of the spring 3d to the pressure roller 4f. When the arm moves downward in the figure, a separation sensor (not shown) detects the separation state of the fixing device F. When the separation sensor detects that the heating film 1f and the pressure roller 4f are separated, the controller CO stops the rotation of the motor M. When the jam processing is completed (when the jam paper is not detected in the fixing nip by the sensor), the controller CO rotates the motor M in the reverse direction until the separation sensor detects contact. As the pressure cam rotates in the reverse rotation direction, the arm is pulled by the spring 3d and returns to the pressure position.

In this way, by controlling forward and reverse rotation of the motor M, the pressure roller 4f can be rotated during image formation by one motor, and workability during jam processing can be improved. Although the fixing device has been described as an example, the present drive train can be applied to various uses such as a portion where a roller for conveying a sheet is selectively rotated, and a rotary developing device is rotationally driven.

§3. {About one-way unit}
Below, the one-way unit 100 as a drive transmission unit which is a characteristic mechanical element of a present Example is demonstrated. As described above, it is incorporated in the drive train D and switches between transmission and interruption of the driving force according to the rotation direction of the motor M.

■ (A perspective view in an assembled state and a perspective view in an exploded state)
FIG. 4A is a perspective view for explaining the appearance of the one-way unit 100 as a drive transmission unit. The one-way unit 100 is provided in a loosely fitted state on the support shaft SH. FIG. 4B is a perspective view for explaining a state in which the one-way unit 100 is disassembled. The one-way unit 100 includes an input gear 100i as a rotatable input member, a cam surface as a first receiving portion, a ratchet surface as a second receiving portion, an intermediate body 100m as an intermediate member, and an output as an output member. It is comprised from the gear 100o. Here, the intermediate body 100m is supported by the support shaft so as to be movable in the axial direction in a closed space between the input gear 100i and the output gear 100o. That is, the one-way unit 100 includes an input gear 100i, an output gear 100i, and an intermediate body 100m interposed between the input gear 100i and the output gear 100o so as to be movable in the axial direction in the axial direction of the support shaft SH. ing. Next, each element will be described in detail. In the present embodiment, the shape (joint shape) for transmitting drive from the intermediate body 100m to the output gear 100o is not limited to the ratchet shape. That is, any shape may be used as long as it has both a portion that converts the rotational driving force input to the input gear 100i into a force in the rotational axis direction and a portion that transmits the rotational driving force by meshing.

■ (Relationship between each element)
FIG. 5A is a perspective view showing a state in which each element (100i, 100m, 100o) constituting the one-way unit 100 is detached from the support shaft SH. FIG. 5B is a cross-sectional view of each element.

As shown in FIG. 5, an input gear 100i as an input member includes a plurality of tooth surfaces (tooth surfaces 101i and 102i). Moreover, the sliding rib 103i which contacts the end surface cam 101m provided in the intermediate body 100m is provided. The input gear 100i includes a guide surface 104i that is guided in a loosely fitted state with the intermediate body 100m, and a guide surface 105i that is guided in a loosely fitted state with the output gear 100o. That is, the input gear 100i has a fitting relationship with a gap (play) in the radial direction of the support shaft SH, and the intermediate body 100m and the output gear 100o have a fitting relationship with a gap (play) in the radial direction. ing.

The surface of the intermediate body 100m facing the input gear is provided with an end face cam 101m that contacts the sliding rib 103i. The surface of the intermediate body 100m facing the output gear is provided with a ratchet surface 102m that transmits drive to the output gear. The intermediate body 100m includes a cylindrical projection surface 103m that can be retracted into a space of the guide surface 104i (concave shape) of the input gear 100i and a peripheral surface 104m that is guided by the guide surface 104o of the output gear.

The output gear 100o includes a tooth surface 101o for transmitting a driving force transmitted from the input gear 100i through the intermediate body 100m. Further, a ratchet surface 102o is provided as a drive receiving portion that engages with the ratchet surface 102m as a drive transmission portion of the intermediate body 100m and receives a rotational driving force.

Also, the outer diameter of the surface 103o of the output gear 100o that contacts the input gear 100i is such that it can idle (relatively rotate) with respect to the input gear 100i. In addition, the output gear 100o includes a concave guide surface 104o that guides the peripheral surface 104m of the intermediate body 100m.

A brief description of each element of the one-way unit 100 was given. Next, the connection relationship between each tooth surface (101i, 102i, 101o) and another gear will be briefly described. It is the tooth surface 102 i that meshes with the gear provided in the motor M. When the motor M rotates, the input gear 100i rotates by the torque received from the tooth surface 102i. Here, when the input gear 100i rotates, a driving force is transmitted from the tooth surface 101i toward the swing gear 1d (second path: see FIG. 2). Similarly, the tooth surface 101o provided on the output gear 100o transmits driving force to the pressure roller 4f (first path: see FIG. 2).

Here, the cam surface (end face cam) of the intermediate body 100m of the present embodiment has an outer diameter of 8.2 mm, a thickness of 1.6 mm, and rotates about 104 ° around the support shaft SH, whereby the axial direction of the support shaft SH It has an inclination to displace the height of 2.3 mm. At both ends of the end face cam, there are two faces substantially parallel to the rotation axis direction. Of the two surfaces, the surface with the shorter length in the axial direction is referred to as the A surface, and the surface with the longer length is referred to as the B surface (see FIG. 6B). When the A surface rotates forward, the B surface contacts the circumferential surface of the sliding rib 103 i when rotating reversely, and receives driving force from the input gear.

Further, the ratchet shape provided in the output gear 100o and the intermediate body 100m has eight claw shapes arranged at equal intervals around the support shaft SH. Each nail shape has an outer diameter of 14.8 mm, a thickness of 3.5 mm, and the slope of the ratchet surface has a slope of about 12 ° (see FIG. 6B). The abutment surface (drive transmission surface) with which the ratchets come into contact is a slope of 2 mm in the axial direction of the support shaft SH and inclined by 5 ° in the direction of biting each other. That is, drive transmission from the intermediate body 100m to the output gear 100o is performed between slopes having a slope of 5 °. Thereby, a force acts on the ratchet portions in a direction to bite each other, and the intermediate body 100m is attracted to the output gear 100o. Therefore, the ratchet portions are not disconnected from each other while the rotation in the positive direction is transmitted to the input gear, and reliable drive transmission can be performed.

Furthermore, since the intermediate body 100m is loosely fitted to the support shaft SH, the intermediate body 100m is parallel to the support shaft SH when the intermediate body 100m meshes with a substantially vertical surface of the ratchet surface of the output gear 100o. Supported. As a result, the driving force input to the input gear from the motor M can be transmitted to the output gear while suppressing loss. In addition, the intermediate body 100m of a present Example has an engaging part of 6.5 mm with respect to the support shaft SH in the axial direction of the support shaft SH. The engaging part has a relationship of 1.5 mm at the cam surface side end of the intermediate body 100 m and a fitting part of 211 ° around the support shaft SH, and the other 5 mm having a clearance of 0.1 mm with respect to the support shaft SH. It has become.

As described above, the intermediate body 100m has a cam surface on the input gear 100i side in the axial direction and a ratchet shape as a joint shape on the output gear 100o side. A sliding rib for pushing up the cam surface of the intermediate body 100m is provided in the input gear 100i, and a ratchet shape for receiving the ratchet shape of the intermediate body 100m is provided in the output gear 100o. Yes. Here, in consideration of the influence of the driving load of the pressure roller 4f, the sliding resistance of each gear, and the like, the end face cam shape and the ratchet shape are adopted in this embodiment, but this configuration is limited as long as the same function can be ensured. It is not a thing. In addition, the one-way unit 100 of this example was made by casting acetal resin (POM).

■ (Detailed explanation about the shape of each element)
Then, each element (100i, 100m, 100o) is demonstrated using a side view. FIG. 6A is a side view of the input gear 100i. The tooth surfaces 101i and 102i are provided concentrically. Moreover, the sliding rib 103i is provided in a part of recessed part by the side of the intermediate body 100m.

Subsequently, FIG. 6B is a side view of the intermediate 100m. It can be seen that an end face cam 101m in which a part of the cylinder is cut out is provided on the surface on the input gear side of the intermediate body 100m. Note that the surface of the sliding rib 103i on the intermediate body 100m side comes into contact with the inclined surface of the end face cam 101m, and pushes the intermediate body 100m toward the output gear 100o. Further, both ends of the cylindrical notch are substantially parallel to the axial direction, and the rotational force in the circumferential direction input to the input gear 100i is good to the intermediate body 100m by contacting the circumferential surface of the sliding rib 103i. To communicate.

Finally, (c) of FIG. 6 is a side view of the output gear 100o. Eight claws that mesh with the ratchet surface 102m are arranged on the surface on the intermediate body 100m side of the output gear 100o in the circumferential direction. When the input gear 100i rotates in the reverse direction, the slope of the output gear 100o releases the role of pushing the intermediate body 100m toward the input gear in the rotation axis direction.

Here, consideration is given to the situation in which the frictional resistance of the contact portion at the drive cutoff position of the cam surface of the input gear 100i and the intermediate body 100m is increased due to the viscosity of the grease. When the frictional resistance at the contact portion is large, the input gear 100i and the intermediate body 100m are rotated together, and there is a possibility that the drive cannot be transmitted to the output gear 100o. However, as described above, the intermediate body 100m and the support shaft SH have a gap in the radial direction of the support shaft SH. For this reason, the intermediate body 100m and the output portion 100o have a fitting (free fitting) relationship in the radial direction of the support shaft SH. Specifically, there is a relationship having a gap of 0.1 mm between the intermediate body 100m of the present embodiment and the support shaft SH.

Thereby, the intermediate body 100m can be inclined with respect to the axial direction of the support shaft SH in the gap provided in the radial direction with the support shaft SH. Furthermore, the intermediate body 100m and the output gear 100o are in a fitting relationship in the radial direction of the support shaft SH. Therefore, when the intermediate body 100o is inclined, the frictional resistance between the intermediate body 100o and the output gear 100o becomes very large, and the contact between the input gear 100i and the intermediate body 100m on the cam surface can be reliably separated. Therefore, even if the frictional resistance at the contact portion between the cam surface of the input gear 100i and the intermediate body 100m becomes large, the rotation of the input gear 100i and the intermediate body 100m is suppressed, and a reliable one-way operation is achieved. Drive transmission is possible.

§4. {Operation of the one-way unit during forward and reverse rotation}
First, the positional relationship of each element at the time of driving transmission and driving interruption of the one-way unit 100 will be described with reference to FIG. Then, the positional change of the intermediate body 100m accompanying switching of a rotation direction is demonstrated using FIG. 8, FIG.

■ (About the positional relationship of each element at the time of drive interruption and drive transmission)
First, the state in which the ratchet surface of the intermediate body 100m is separated from the ratchet surface of the output gear and the state in contact with the ratchet surface will be described.

A: The ratchet surfaces are separated from each other (when the drive is cut off)
FIG. 7A is a diagram for explaining a state in which the intermediate body 100m is in a separated position where the ratchet surface of the intermediate body 100m and the ratchet surface of the output gear 100o do not contact each other. In this state, the ratchet surface of the intermediate body 100m and the ratchet surface of the output gear 100o are in a positional relationship such that they do not contact each other. At this time, the sliding rib of the input gear 100i is at a deep position (blocking position) of the end face cam. In this state, when the input member rotates in the reverse direction, the sliding rib comes into contact with the B surface of the intermediate body 100m, and when the input member rotates in the forward direction, the sliding rib comes into contact with the end face cam of the intermediate body. Move to the side (output member side).

B: The ratchet surfaces are in contact (meshing) with each other (during drive transmission)
FIG. 7B is a view for explaining a state in which the intermediate body 100m is in a contact position where the ratchet surface of the intermediate body 100m meshes with the ratchet surface of the output gear 100o. In this state, the sliding rib of the input gear 100i is in contact with the A surface of the intermediate body. When the input gear rotates in the forward direction, the sliding rib contacts the surface A to transmit the driving force, and the driving force is transmitted to the output gear through the meshing ratchet surface. In the state where the ratchet surfaces mesh with each other, the sliding rib is in a shallow position (transmission position) of the end face cam. Even if reverse rotation is driven by the input gear from this state, the intermediate body 100m does not move in the axial direction until the sliding rib 103i contacts the B surface of the intermediate body.

■ (About the movement of the intermediate in the axial direction when the rotation direction is changed)
Subsequently, the movement of the intermediate body accompanying the switching of the rotation direction will be described in detail.

A: Movement of intermediate body to contact state (during forward rotation)
FIG. 8 is a diagram for explaining how the intermediate body 100m moves when the input gear 100i rotates in the forward direction. (A) of FIG. 8 is a figure which shows the state which the ratchet surface of the intermediate body 100m and the ratchet surface of the output gear 100o have not meshed | engaged. At this time, the sliding rib 103i is positioned at the blocking position of the end face cam, and the peripheral surface of the sliding rib is in contact with the B surface of the intermediate body. When the input gear 100i rotates in the forward direction in this state, the sliding rib 103i moves away from the B surface of the end cam, and the intermediate rib side surface of the sliding rib comes into contact with the cam surface.

FIG. 8B is a diagram for explaining what force the sliding rib 103i applies to the end face cam surface as it rotates in the forward direction. The sliding rib 103i rotates integrally with the input gear 100i in the positive direction. At this time, the sliding rib applies a force in the direction of a thin arrow in the figure to the end face cam. The intermediate body 100m receives an axial component force (thick arrow in the figure) from the sliding rib and moves from the separated position toward the contact position.

(C) of FIG. 8 is a diagram for explaining that the driving force is transmitted from the input gear 100i to the output gear 100o through the intermediate body 100m. When the input gear 100i rotates in the forward direction, the sliding rib 103i comes into contact with the A surface of the intermediate body 100m. The intermediate body 100m that receives the force transmitted from the sliding rib on the A surface transmits the rotational force in the positive direction to the output gear 100o through the ratchet surface. As described above, when the input gear 100i rotates forward, the intermediate body 100m moves to the contact position, and the rotational driving force is transmitted to the downstream side of the output gear. Thus, when the input gear rotates in the forward direction, the resultant force of the force applied to the intermediate body by the input gear and the force applied to the intermediate body by the output gear is a direction toward the output gear along the axial direction.

B: Movement of intermediate body to retracted position (during reverse rotation)
FIG. 9 is a diagram for explaining how the intermediate body 100m moves when the input gear 100i rotates in the reverse direction.

FIG. 9A is a view showing a state in which the ratchet surface of the intermediate body 100m and the ratchet surface of the output gear 100o are in contact (engaged). At this time, the sliding rib 103i is positioned at the transmission position of the end face cam, and the peripheral surface of the sliding rib is in contact with the A surface of the intermediate body. When the input gear 100i rotates in the reverse direction in this state, the sliding rib 103i moves away from the B surface of the end cam. Since the intermediate body 100m is not biased by a spring or the like, the intermediate body does not rotate or move until the sliding rib 103i contacts the A surface of the intermediate body.

(B) of FIG. 9 is a diagram for explaining what force is applied to the intermediate body by the ratchet surface of the output gear 100o. When the sliding rib 103i comes into contact with the B surface, the intermediate body 100m rotates in the reverse direction integrally with the input gear 100i. When the intermediate body 100m rotates in the reverse direction, the ratchet surface of the output gear comes into contact with the inclined surface of the intermediate body ratchet surface. At this time, the ratchet surface of the output gear applies a force in the direction of a thin arrow in the figure to the ratchet surface of the intermediate body. The intermediate body 100m receives an axial component force (thick arrow in the figure) from the ratchet surface of the output gear 100o, and moves from the contact position toward the separation position.

(C) of FIG. 9 is a figure for demonstrating that the intermediate body 100m which moved to the separation position does not move to a contact position during reverse rotation. In this embodiment, the intermediate body 100m is not biased so as to move to the contact position by a biasing means such as a spring. Therefore, if the ratchet surfaces move to a position where the ratchet surfaces do not mesh with each other due to the component force from the ratchet surface of the output gear 100o, the inclined surfaces do not collide again. In this state, since the sliding rib 103i and the B surface of the intermediate body are in contact with each other, the intermediate body 100m rotates integrally with the input gear 100i in the reverse direction. Thus, when the input gear rotates in the reverse direction, the resultant force of the force applied to the intermediate body by the input gear and the force applied to the intermediate body by the output gear is in the direction toward the input gear along the axial direction.

§5. {Operation sound during reverse rotation of one-way unit}
Finally, the operation sound when the one-way unit of the comparative example and the present embodiment is reversely rotated (drive cut off) is compared.

■ (Comparative example)
FIG. 11 is a view for explaining the configuration of a one-way clutch of a comparative example. The ratchet surface provided in the intermediate body 100m of this example was provided on the input side, and was biased by a spring so as to contact the ratchet surface on the output side. Here, the one-way clutch of the comparative example was also pressurized with 1N by a spring using POM as in the present example.

When the drive transmission is cut off in the configuration as in the comparative example, the input side and the output side move up on the slope of the ratchet against the spring force (see idle rotation in the figure). And every time it gets over the slope of the ratchet, the input side and the output side collide by the spring, and a periodic impact sound (collision sound) continues to sound.

■ (Comparison result)
Below, the comparison result of a present Example and a comparative example is shown briefly. Table 1 compares the sound pressure levels measured in the vicinity of the exterior of the printer 1 when the input side is rotated in the reverse direction (drive cutoff direction) at 220 rpm.

As shown in Table 1, it was possible to reduce the sound pressure level during reverse rotation compared to the configuration of the comparative example. Note that when the configuration of the comparative example is rotated in the reverse direction, the increase in the sound pressure level due to the periodic impact sound generated from the one-way unit is about 15 dB (the remaining 35 dB is a sound generated from other elements). That is, it can be said that the sound generated during reverse rotation from the one-way unit 100 according to the present embodiment is a level (substantially 0 dB) generated by the meshing of the gears.

In this way, the one-way unit of this embodiment makes the operation noise when the drive is shut down quieter than the configuration (comparative example) in which the pawl that has overcome the ratchet surface by the biasing by the spring is always biased to the meshing position. Can do. In this way, it is possible to reduce the impact noise at the connecting portion while selectively transmitting the drive with a relatively small number of parts. In addition, since an intermediate body can be comprised with a resin material (POM) compared with a prior art (patent document 2), it becomes possible to transmit high load. This is because in the configuration in which the rotational driving force is transmitted by the spring material as in the prior art, if a spring material that can withstand a high load is used, deformation becomes difficult and the function of selectively transmitting the drive is impaired. Further, the configuration of the present embodiment has an advantage that the occupied space can be reduced because a portion for holding the other end is not required for biasing the output side with a spring as compared with the comparative example.

Hereinafter, the configuration of this embodiment will be described. Note that a description of the same parts as those in the first embodiment will be omitted.

FIG. 10 is a diagram for explaining the configuration of the one-way unit of this embodiment. In the first embodiment, the intermediate body 100m is pushed to the contact position by the sliding rib 103i during the forward rotation, and is pushed toward the separation position by the ratchet surface 102o during the reverse rotation. On the other hand, the one-way unit 100 of the present embodiment employs a configuration in which the sliding rib 103i pulls the intermediate body 100m toward the separation position during reverse rotation (see FIG. 10A).

Also, the shape of the drive transmission portion that transmits to the output gear 100o when a positive rotational driving force is transmitted to the input gear 100i has been changed from a ratchet shape having a slope to a protruding shape. Naturally, since the configuration in which the intermediate body 100m is pulled in as in this embodiment is adopted, the joint shape is not limited to the protrusion shape as long as the circumferential rotational driving force can be transmitted.

Subsequently, the configuration in which the input gear 100i as the input member pulls in the intermediate body 100m as the intermediate member to the input member side during reverse rotation will be described in detail. FIG. 10B is a diagram in which a contact portion between the input gear 100i and the intermediate body 100m is cut in the axial direction and developed in the circumferential direction. In addition, the shape for drawing in the intermediate body 100m as in the present embodiment is a relatively complicated shape compared to the configuration of the sliding rib 103i and the end face cam in the first embodiment, and there is a demerit that the manufacturing costs increase. . On the other hand, since the constraints on the shape of the drive transmission surface are relaxed, a joint shape that can improve the idling distance and drive transmission accuracy can be employed. Specifically, in the present embodiment, the number of pins that perform drive transmission is larger than the number of claws (eight) of the drive transmission section of the first embodiment.

As in the first embodiment, when the input gear 100i rotates in the forward direction, the sliding rib 103i comes into contact with the A surface of the intermediate body 100m, and the intermediate body 100m moves to the contact position. On the contrary, when the input gear 100i rotates in the reverse direction, the sliding rib 103i comes into contact with the B surface of the intermediate body. In the present embodiment, the shape of the side of the sliding rib 103i that contacts the B surface is a hook shape. Similarly, the B surface of the intermediate body 100m is tapered in the axial direction, and the intermediate body 100m is drawn toward the input gear by the sliding rib 103i during reverse rotation. By configuring in this way, the one-way unit of this embodiment produces an operating sound when the drive is cut off, compared to a configuration (comparative example) in which the pawl that has overcome the ratchet surface by the biasing by the spring is always biased to the meshing position. Can be quiet.

The present invention is not limited to the above embodiment, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to make the scope of the present invention public, the following claims are attached.

1 Printer (image forming device)
F fixing device 1f heating film (heating member)
4f Pressure roller (pressure member)
M motor (drive source)
D Gear train (drive transmission path)
1d Swing gear 2d Pressure release cam 100 One-way unit (drive transmission unit)
100i input gear (input member)
103i sliding rib 100m intermediate (intermediate member)
101m end face cam (circumferential cam)
102m ratchet surface (drive transmission part)
100o output gear (output member)
102o Ratchet surface (drive receiving part)

Claims

An input member that can be rotated by receiving forward and reverse driving forces input from a driving source;
An intermediate member movable in the rotational axis direction of the input member;
An output member that rotates by receiving a driving force from the input member via the intermediate member when the input member rotates in the positive direction;
The intermediate member receives a force converted from a rotational drive force in the positive direction input to the input member into a force in a direction to move the drive force to the output member along the rotational axis direction. A receiving portion, and a second receiving portion that receives a force obtained by converting a rotational driving force in the reverse direction input to the input member into a force in a direction of retreating from a position of driving force to the output member along the rotational axis direction. A drive transmission unit comprising:
When the input member rotates in the forward direction, the resultant force of the force applied by the input member to the intermediate body and the force applied by the output member to the intermediate body is directed toward the output member along the rotational axis direction. The drive transmission unit according to claim 1, wherein the drive transmission unit is a direction.
When the input member rotates in the reverse direction, the resultant force of the force applied by the input member to the intermediate body and the force applied by the output member to the intermediate body is directed toward the input member along the rotational axis direction. The drive transmission unit according to claim 1, wherein the drive transmission unit is a direction.
The first receiving portion is a cam provided on a surface of the intermediate member facing the input member;
The said cam receives the force of the direction which moves the said intermediate member to the position which transmits a driving force to the said output member along the rotating shaft direction from the said input member rotated to a positive direction. Drive transmission unit.
The second receiving portion is a ratchet provided on a surface of the intermediate member facing the output member;
The ratchet is retracted from a position where the intermediate member rotated integrally with the input member rotating in the reverse direction and the output member rotate relative to each other, and the intermediate member is driven along the rotational axis direction to the output member. The drive transmission unit according to claim 1, wherein the drive transmission unit receives a force in a direction of moving.
The drive transmission unit according to claim 1, wherein the intermediate member moves in a space surrounded by the input member and the output member.
An input member that can be rotated by receiving forward and reverse driving forces input from a driving source;
An intermediate member movable in the rotational axis direction of the input member;
An output member that rotates by receiving a driving force from the input member via the intermediate member when the input member rotates in the positive direction;
When the input member rotates in the forward direction, the intermediate member receives a force in the direction of moving from the input member toward the output member from the input member, and when the output member rotates in the reverse direction. The drive transmission unit, wherein the intermediate member receives force from the output member in a direction of moving from the output member toward the input member.
An input member that can be rotated by receiving forward and reverse driving forces input from a driving source;
An intermediate member movable in the rotational axis direction of the input member;
An output member that rotates by receiving a driving force from the input member via the intermediate member when the input member rotates in the positive direction;
When the input member rotates in the forward direction, the intermediate member receives a force in the direction of moving from the input member toward the output member from the input member, and when the output member rotates in the reverse direction. The drive transmission unit, wherein the intermediate member receives a force in a direction of moving from the output member toward the input member from the input member.