JP2010107008A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain stable operation and an output image quality of an image forming apparatus, by providing a clutch mechanism for achieving higher stability and reliability. <P>SOLUTION: The image forming apparatus has looseness (clearance) arranged between a delay gear 52 and a clutch shaft 56, that is, looseness capable of rotating only the clutch shaft 56 up to engaging with the delay gear 52 when the clutch shaft 56 rotates in the rotational direction for transmitting driving, and an initial torque generating spring 53 for biasing the delay gear 52 in the rotational direction to the clutch shaft 56, and enables steady torque to act after predetermined initial torque smaller than the steady torque acts on a movable ratchet 50 and a fixed ratchet 51 for a specific time, after engaging the movable ratchet 50 and the fixed ratchet 51, when the clutch mechanism performs connecting operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer having a function of forming an image on a recording material such as a sheet.

  In an image forming apparatus, it is necessary to selectively supply driving to many elements constituting the apparatus. However, individually arranging motors for these elements and switching driving connection / disconnection with an electromagnetic clutch leads to adverse effects such as an increase in product cost and an increase in power consumption.

  Therefore, a clutch mechanism that mechanically switches connection / disconnection of the drive is generally used in a case that can be substituted.

  Two main specific examples are given below. FIG. 7 is a schematic diagram showing a schematic configuration of a conventional clutch mechanism, in which (a) shows a case where a pair of ratchets and (b) uses a pair of gears.

  One is to switch the engagement and separation of a pair of opposing ratchets 100 and 101 (coupling) by moving one of them 100 in the axial direction of the rotational drive to be transmitted (Patent Document 1, 2).

  The other is to switch the engagement / separation between the pair of gears 102 and 103 by moving one of them 103 (see Patent Document 3). Here, these gears and ratchet couplings that deliver the drive are hereinafter defined as drive transmission means (drive transmission member). A switching mechanism such as a control cam or a control link (not shown) is operated under some trigger to move the movable drive transmission means 100 and 103.

The moving configuration of the movable drive transmission means 100 and 103 is classified into the following three patterns. (1) Energize in the drive coupling direction and move in the separation direction by the switching means when the drive is disconnected.
(2) Energize in the drive cutting direction, and move in the connecting direction by the switching means at the time of driving connection.
(3) The urging is not performed, and the switch is forcibly moved in both the connecting and separating directions.

However, in the methods (2) and (3), even when the drive transmission means cannot be engaged with each other, the switching means forcibly pushes the drive transmission means on the movable side into the other party, so that the mechanism is damaged. There is a fear. For this reason, the actual product generally employs the configuration (1) that can ensure safety.
JP 2003-208024 A JP 2006-308007 A JP 2007-031023 A

  However, the clutch mechanism having the configuration (1) described above is in a state where the engagement between the drive transmission means is shallow when the drive transmission means on the input side is driven and connected while being rotationally driven. The problem that the connection operation stops due to the meshing resistance may occur. The cause of this is as described below.

  Normally, when designing the clutch mechanism, various parameters are set so that the propulsive force in the coupling direction is larger than the resistance force when coupling the drive transmission means. FIGS. 8A and 8B are diagrams for explaining mechanically when the clutch mechanism is engaged, wherein FIG. 8A is a schematic cross-sectional view, and FIG. 8B is an enlarged view of a main part. As shown in FIG. 8, N is the contact force acting on the engaging portion of the drive transmission means during drive transmission, F is the biasing force by the biasing means, θ is the pulling angle of the engaging portion, and When the friction coefficient is defined as μ, the conditional expression is as follows.

  Usually, if the engagement amount L at the moment when the engaging portions of the drive transmission means are engaged with each other is secured to some extent, the connecting operation is performed to the end according to this condition.

  However, when drive coupling is performed while the input side is rotationally driven, the phase relationship between the drive transmission means at the time when the coupling operation is started cannot be managed, and the engagement amount L at the moment of meshing is It can be any way.

  When the engagement amount L at the moment of meshing is very small, the contact pressure acting on the engaging portion, that is, the stress increases, so that the engaging portion is deformed. When the deformation occurs, the value of θ changes, and as a result, when the conditional expression cannot be satisfied, the connecting operation is not normally performed. When the engagement amount L is very small, tooth skipping occurs at the time of connection. When the engagement amount L is within a certain range, the resistance and propulsive force of the connection operation are balanced, and the connection operation stops midway. When the coupling operation is stopped when the engagement between the engagement parts is shallow, if the driving torque on the driven side is stable, the clutch mechanism is in the coupled state while the balance between the resistance force and the propulsive force is maintained. To maintain.

  However, when the driving torque fluctuates in the increasing direction, the balance is lost and tooth skipping occurs, and the driving is instantaneously cut until the engaging portions become the meshing phase. Suddenly disconnecting the drive is a major problem in maintaining the stable operation of the image forming apparatus and the quality of the output image.

  The present invention has been made in view of the above circumstances, and maintains a stable operation of the image forming apparatus and the quality of the output image by providing a clutch mechanism that realizes higher stability and reliability. Objective.

In order to achieve the above object, the present invention provides:
A pair of drive transmission members that are rotatably provided and transmit drive by engaging each other;
By moving one of the pair of drive transmission members in the rotation axis direction, the state of the pair of drive transmission members includes an engagement state in which the pair of drive transmission members are engaged with each other, and a release state in which the engagement state is released. One of the moving means,
Switching to switch the state of the pair of drive transmission members between the engagement state and the release state by moving one of the pair of drive transmission members in the direction of the rotation axis by the moving means. Means,
An image forming apparatus for forming an image on a recording material,
A pair of rotating members configured to form a drive train from a drive source to the driven portion via the pair of drive transmission members and engaged with each other to transmit drive;
A gap provided between the pair of rotation members, wherein the first rotation member on the drive source side of the pair of rotation members transmits the drive transmission when the pair of drive transmission members are in the engaged state. A gap that allows only the first rotating member to rotate until it engages with the second rotating member on the driven portion side of the pair of rotating members
An urging means provided between the pair of rotating members and urging the second rotating member with respect to the first rotating member in the rotation direction;
It is characterized by providing.

  According to the present invention, it is possible to maintain the stable operation of the image forming apparatus and the quality of the output image by providing the clutch mechanism that realizes higher stability and reliability.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  A first embodiment to which the present invention can be applied will be described with reference to FIGS.

  FIG. 5 is a schematic cross-sectional view of an image forming apparatus to which the present invention is applied.

  In FIG. 5, reference numeral 1 denotes a printer main body. On the upper portion of the printer main body 1, primary images of a total of four colors of yellow, magenta, cyan, and black (hereinafter abbreviated as Y, M, C, and K) are displayed. The engine part for forming is laid out.

  Print data transmitted from an external device such as a PC is received by a controller that controls the printer main body 1, and is output as write image data to the laser scanners 10a and 10b corresponding to each color. The laser scanner irradiates the photosensitive drum 12 with a laser and draws an optical image according to the written image data.

  In the image forming apparatus of the present embodiment, an optical image is written by two laser scanners, a first scanner 10a that performs laser irradiation for yellow and magenta, and a second scanner 10b that performs laser irradiation for cyan and black. . In this embodiment, each laser scanner adopts a configuration in which laser light for two stations is scanned by one polygon mirror.

  The engine portion includes a toner cartridge 15 for supplying toner and a process cartridge 11 for forming a primary image in each of the Y, M, C, and K stations.

  The process cartridge 11 includes a photosensitive drum 12, a charger 13, a developing device 14, and a cleaner. Here, the charger 13 is for uniformly charging the surface of the photosensitive drum 12. The developing device 14 converts the electrostatic latent image created by the laser scanner 10 to draw an optical image on the surface of the photosensitive drum 12 charged by the charger 13 into a toner image to be transferred to the intermediate transfer belt 34. It is for developing. The cleaner is for removing the toner remaining on the photosensitive drum 12 after transferring the toner image.

  A primary transfer roller 33 for transferring the toner image developed on the surface of the photosensitive drum 12 to the intermediate transfer belt 34 is disposed at a position facing the photosensitive drum 12.

  The toner image (primary image) transferred to the intermediate transfer belt 34 is obtained by a secondary transfer roller 31 that also serves as a driving roller for the intermediate transfer belt 34 and a secondary transfer outer roller 24 that faces the secondary transfer roller 31. Retransferred onto the recording material. The toner remaining on the intermediate transfer belt 34 without being transferred to the recording material in the secondary transfer portion is collected by the intermediate transfer belt cleaner 18.

  The feeding unit 20 is located in the uppermost stream in the recording material conveyance direction, and is provided in the lower part of the printer main body 1. When the recording material loaded and stored in the feeding tray 21 is fed by the feeding unit 20, the recording material passes through the vertical conveyance path 22 and is conveyed downstream. The longitudinal conveyance path 22 is provided with a registration roller pair 23, where final skew correction of the recording material, and timing adjustment of image writing and recording material conveyance in the image forming unit are performed.

  A fixing device 25 for fixing the toner image on the recording material as a permanent image is provided downstream of the image forming unit in the recording material conveyance direction. Further, on the downstream side of the fixing device 25 in the recording material conveyance direction, a discharge conveyance path continuing to the discharge roller 26 for discharging the recording material from the printer main body 1 is provided. The recording material discharged by the discharge roller 26 is received by a discharge tray 27 provided outside the printer main body 1.

  Below, the application part of the clutch mechanism which concerns on a present Example, and the detail of a clutch mechanism are demonstrated.

  In this embodiment, the clutch mechanism is applied to the drive control unit of the developing device of the process cartridge in the printer main body 1.

  In general, the elements constituting the developing unit that controls image formation must minimize the drive time other than the image forming operation in order to maximize the durability life. For this reason, it is necessary to sequentially switch the driving of each station at a predetermined timing at the start or end of the image forming operation, including the contact / separation operation with respect to the photosensitive drum.

  In the image forming apparatus of this embodiment, four clutch mechanisms are provided corresponding to the developing devices of the respective stations, and connection / disconnection of the drive is mechanically controlled using a common link mechanism.

  In addition, this common link mechanism is configured to simultaneously control the contact / separation operation of the developing device with respect to the photosensitive drum. It is executed in a prescribed order and timing. Note that the abutment / separation configuration of the developing device and the relationship of the control timing between the stations are not the essence of the present embodiment, and thus the description thereof is omitted.

  FIG. 1 is a diagram illustrating the configuration of the clutch mechanism employed in the image forming apparatus of this embodiment.

  The clutch mechanism is roughly composed of the following four units. An input unit responsible for drive input, an output unit responsible for drive output to the driven part, a control unit for controlling drive connection / disconnection of both, and an initial torque lower than the steady torque for a predetermined time immediately after drive connection These are four of the initial torque generating units for causing Here, the steady torque is a torque necessary for driving the driven part.

  The input unit includes an input gear 54, a movable ratchet (coupling) 50, and a biasing spring 55 that biases the movable ratchet 50 toward the fixed ratchet (coupling) 51 of the output unit.

  The movable ratchet 50 is disposed inside the input gear 54 and is configured to rotate integrally with the input gear 54 and to be slidable in the axial direction of the clutch shaft 56. The input unit is provided so as to be rotatable with respect to the clutch shaft 56.

  The output unit includes a clutch shaft 56 that is rotatably supported by the printer main body 1 by a guide member 59 and a bearing 60, and a fixed ratchet 51 that is fixed to the clutch shaft 56 and rotates integrally.

  Here, the movable ratchet 50 and the fixed ratchet 51 correspond to a pair of drive transmission members. The movable ratchet 50 and the fixed ratchet 51 are rotatably provided, and the input unit and the output unit are drivingly coupled by engaging with each other to transmit driving.

  The control unit includes a guide member 59, a control cam 57, and a movable cam 58. Here, the guide member 59 is disposed coaxially with the clutch shaft 56 and is fixed to the printer main body 1. The control cam 57 is pivotally supported with respect to the guide member 59. The movable cam 58 is supported by the guide member 59 so that its rotation is slidable in the axial direction of the clutch shaft 56.

  Here, the urging spring 55 and the movable cam 58 correspond to a moving unit that moves the movable ratchet 50 in the rotation axis direction (the axial direction of the clutch shaft 56). The control cam 57 corresponds to switching means.

  When the control cam 57 rotates by the action of a clutch control mechanism (control means) (not shown), the movable cam 58 engaged with the control cam 57 moves in the axial direction of the clutch shaft 56. The movable cam 58 is in a slidable contact state with the movable ratchet 50 of the input unit, and the movable ratchet 50 also moves in conjunction with the movement of the movable cam 58. The movable ratchet 50 and the fixed ratchet 51 are disposed on the same rotation shaft and have engaging claws that protrude toward the opposing surfaces. Therefore, when the movable ratchet 50 moves to the fixed ratchet 51 side, both engaging claws are engaged, and the movable ratchet 50 and the fixed ratchet 51 are in an engaged state.

  By this mechanism, the clutch cam can be switched between connection and disconnection by controlling the phase of the control cam 57.

  The initial torque generating unit includes a delay gear 52 and an initial torque generating spring 53.

  The delay gear 52 is supported with a backlash of a predetermined angle in the rotational direction with respect to a clutch shaft 56 that is engaged with each other to transmit drive. This play is a gap provided between the delay gear 52 and the clutch shaft 56 (between a pair of rotating members), and when the clutch shaft 56 rotates in the rotational direction for transmitting drive, the delay gear 52. This is a gap that allows only the clutch shaft 56 to rotate until it is engaged. Here, the delay gear 52 and the clutch shaft 56 constitute a drive train from the drive source to the driven part via the pair of drive transmission members, and a pair of rotating members that perform drive transmission by engaging with each other. It corresponds to. The delay gear 52 corresponds to the second rotating member on the driven part side of the pair of rotating members, and the clutch shaft 56 corresponds to the first rotating member on the driving source side of the pair of rotating members.

The initial torque generating spring 53 urges the delay gear 52 in the play expansion direction (the direction in which the gap increases) with respect to the rotational drive transmission direction in order to increase the play of the delay gear 52. Here, the initial torque generating spring 53 corresponds to an urging means. The magnitude of the biasing force of the initial torque generating spring 53 is smaller than the steady torque required to drive the driven part.

  Next, the operation of the clutch mechanism of the present embodiment will be described with reference to FIGS.

  In this embodiment, when the clutch mechanism performs the coupling operation, the movable ratchet 50 and the fixed ratchet 51 are engaged, and then a predetermined initial torque smaller than the steady torque is applied to the movable ratchet 50 and the fixed ratchet 51 for a certain period of time. Later, steady torque is applied.

  2A and 2B are operation explanatory views of the clutch mechanism in this embodiment, where FIG. 2A shows a standby state, FIG. 2B shows a connection operation, and FIG. 2C shows a connection completion. 2A to 2C, a schematic cross-sectional view is shown on the left side, and a schematic perspective view is shown on the right side. Note that, in the cross-sectional view shown in FIG. 2, only the minimum parts necessary for explanation are shown for easy understanding of the operation.

  FIG. 3 is an explanatory diagram of the operation of the initial torque generating unit in the clutch mechanism according to the present embodiment, where (a) shows a standby state, (b) shows a connecting operation, and (c) shows a completed connection.

  In the standby state (the state shown in FIGS. 2A and 3A), the movable ratchet 50 is in a position where it is pushed by the movable cam 58 and retracted from the fixed ratchet 51. At this time, the driving of the input unit and the output unit is disconnected (the movable ratchet 50 and the fixed ratchet 51 are in a released state where they are not engaged).

  When the connecting operation is started and the control cam 57 starts rotating, the movable ratchet 50 moves to the fixed ratchet 51 side, the engaging claws of both engage, and the movable ratchet 50 and the fixed ratchet 51 are in the engaged state. (The state shown in FIGS. 2B and 3B). At this time, although the input unit and the output unit are drivingly connected, the drive is not yet transmitted to the gear 61 on the driven portion side (driven side), and first, relative delay between the delay gear 52 and the clutch shaft 56 at a predetermined angle. Begins to be consumed. Until the relative play becomes completely zero, the torque generated by the initial torque generating spring 53 (a predetermined initial torque smaller than the steady torque) is the movable ratchet 50 and the fixed ratchet 51, that is, the drive train of the clutch mechanism. Is in a state of acting on. During this time, the movable ratchet 50 moves to a position where the meshing with the fixed ratchet 51 is greater than or equal to the engagement amount necessary for stable operation of the clutch mechanism.

  When the relative play between the delay gear 52 and the clutch shaft 56 is completely consumed, a steady torque acts on the movable ratchet 50 and the fixed ratchet 51, that is, the drive train of the clutch mechanism, and the drive of the driven gear 61 is started. (The state shown in FIGS. 2C and 3C).

  In a series of drive coupling processes, the relationship between the drive torque acting on the drive train and time is as shown in the graph of FIG. FIG. 4 is a diagram showing drive torque transition during the coupling operation of the clutch mechanism of the present embodiment.

  In the figure, A is a point where the engaging claws of the movable ratchet 50 and the fixed ratchet 51 are engaged with each other, and B is a point where consumption of relative play between the delay gear 52 and the clutch shaft 56 is completed.

  Similarly, the drive disconnection is performed when the movable ratchet 50 moves and the engagement relation with the fixed ratchet 51 is released. At the moment when the drive is cut and the fixed ratchet 51 is released, the clutch shaft 56 is reversed by the action of the delay gear 52 and the initial torque generating spring 53 to recover a predetermined relative play relative to the delay gear 52.

  As described above, according to the present embodiment, a clutch mechanism having higher stability and reliability can be realized.

  In the conventional clutch mechanism, the steady torque on the driven side acts on the drive transmission means from the moment of driving connection. On the other hand, in the clutch mechanism of this embodiment, when the clutch mechanism performs the coupling operation, the engagement portion on the drive input side and the drive output side abuts, and then the engagement portion has a predetermined initial value smaller than the steady torque. After the torque acts for a certain time, the steady torque acts. By setting the initial torque to a value that can guarantee the stability of the drive connection operation, the drive connection operation can be surely completed without depending on the conditions at the time of connection. As a result, the problem of operational stability that the conventional clutch mechanism has has been dramatically improved.

  In Example 1, although the example which used the ratchet (coupling) as a drive transmission member was shown, this invention is not limited to this. Further, the present invention is not limited to the first embodiment with respect to the configuration of the drive connection / disconnection switching means. In the second embodiment, a configuration using a gear as a drive transmission member will be described as another embodiment.

  Example 2 will be described with reference to FIG.

  6A and 6B are operation explanatory views of the clutch mechanism in the present embodiment, where FIG. 6A shows a standby state, FIG. 6B shows a connection operation, and FIG. 6C shows a connection completion. The configuration of the image forming apparatus and the location where the clutch mechanism is applied are the same as those in the first embodiment, and the description thereof is omitted. In FIG. 6, the same numbers are assigned to components having the same functions as those in the first embodiment.

  Similarly to the first embodiment, the clutch mechanism of the present embodiment is roughly composed of four units. It consists of an input unit responsible for drive input, an output unit responsible for drive output to the driven side, a control unit for controlling drive connection / disconnection of both, and an initial torque lower than the steady torque for a predetermined time immediately after drive connection. It is an initial torque generating unit for acting.

  The input unit includes an input gear 70 that is rotatably supported by a shaft (not shown) and is rotated by a drive supply from a drive source.

  The output unit includes a clutch shaft 75 that is rotatably supported by the printer body 1, a movable gear 71 that rotates integrally with the clutch shaft 75 and that is slidable in the axial direction of the clutch shaft 75, and a movable gear 71. The urging spring 76 is urged in the sliding direction.

  The control unit includes a control mechanism (not shown) and a control arm 77 that is controlled to swing by the control mechanism. The front end of the control arm 77 can be brought into contact with and separated from a contact rib provided on the side surface of the movable gear 71.

  As in the first embodiment, the initial torque generating unit has a delay gear 52 that is fixed with a backlash of a predetermined angle in the rotational direction with respect to the clutch shaft 75, and the backlash of the delay gear 52 is increased in the backlash transmission direction. It comprises an initial torque generating spring 53 that biases in the direction.

  The torque generated by the initial torque generating spring 53 is set to the minimum necessary value that can guarantee the stable operation of the clutch mechanism.

  In the standby state (FIG. 6A), the movable gear 71 is retracted to a position where it is pushed by the control arm 77 and does not mesh with the input gear 70, and the drive is cut off.

  When the connecting operation is started and the control arm 77 starts to rotate, the movable gear 71 starts to move toward the input gear 70, and both tooth surfaces engage with each other (FIG. 6B).

  At this time, although the input unit and the output unit are drivingly connected, the drive is not yet transmitted to the driven gear 78, and the relative backlash of the delay gear 52 and the clutch shaft 75 starts to be consumed first. Until this relative play becomes completely zero, the torque generated by the initial torque generating spring 53 is in a state of acting on the drive train of the clutch mechanism. During this time, the movable gear 71 completes its movement to a position where the meshing of the tooth surface with the input gear 70 becomes the amount of engagement necessary for stable operation of the clutch mechanism.

  When the relative play between the delay gear 52 and the clutch shaft 75 is completely consumed, the drive of the driven gear 78 is started (FIG. 6C). In a series of drive coupling processes, the relationship between the drive torque acting on the drive train and time is the same as that shown in the graph of FIG.

  Similarly, the drive disconnection is performed by moving the movable gear 71 to disengage the tooth surface from the input gear 70. At the moment when the drive is cut and the movable gear 71 is released, the clutch shaft 75 is reversed by the action of the delay gear 52 and the initial torque generating spring 53 to recover a predetermined relative play relative to the delay gear 52.

  According to the present embodiment, it is possible to obtain the same effect as in the first embodiment.

FIG. 3 is a configuration explanatory diagram of a clutch mechanism in Embodiment 1. FIG. 6 is an operation explanatory diagram of the clutch mechanism in Embodiment 1. FIG. 6 is an operation explanatory diagram of an initial torque generating unit in the clutch mechanism of the first embodiment. The figure which shows drive torque transition during the connection operation | movement of the clutch mechanism of Example 1. FIG. 1 is a schematic sectional view of an image forming apparatus to which the present invention is applied. FIG. 9 is an operation explanatory diagram of a clutch mechanism in Embodiment 2. Schematic of a conventional clutch mechanism. FIG. 6 is an explanatory diagram of mechanics when the clutch mechanism is engaged.

Explanation of symbols

DESCRIPTION OF SYMBOLS 50 Movable ratchet 51 Fixed ratchet 52 Delay gear 53 Initial torque generating spring 55 Energizing spring 56 Clutch shaft 57 Control cam 58 Movable cam

Claims (4)

A pair of drive transmission members that are rotatably provided and transmit drive by engaging each other;
By moving one of the pair of drive transmission members in the rotation axis direction, the state of the pair of drive transmission members includes an engagement state in which the pair of drive transmission members are engaged with each other, and a release state in which the engagement state is released. One of the moving means,
Switching to switch the state of the pair of drive transmission members between the engagement state and the release state by moving one of the pair of drive transmission members in the direction of the rotation axis by the moving means. Means,
An image forming apparatus for forming an image on a recording material,
A pair of rotating members configured to form a drive train from a drive source to the driven portion via the pair of drive transmission members and engaged with each other to transmit drive;
A gap provided between the pair of rotation members, wherein the first rotation member on the drive source side of the pair of rotation members transmits the drive transmission when the pair of drive transmission members are in the engaged state. A gap that allows only the first rotating member to rotate until it engages with the second rotating member on the driven portion side of the pair of rotating members
An urging means provided between the pair of rotating members and urging the second rotating member with respect to the first rotating member in the rotation direction;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein an urging force by the urging unit is smaller than a steady torque necessary for driving the driven part.   The image forming apparatus according to claim 1, wherein the pair of drive transmission members are a pair of gears.   3. The image according to claim 1, wherein the pair of drive transmission members are couplings or ratchets having engagement claws that are disposed on the same rotation shaft and protrude toward the opposing surfaces. 4. Forming equipment.

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