JP2018056164A - Opening and closing mechanism and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an opening and closing mechanism and an image formation device capable of reducing the operating force when opening and closing an opening and closing door.SOLUTION: An opening and closing mechanism includes an opening and closing door rotary supported movably between a close position for closing the opening of the device body and an open position for opening the opening, a link member provided in the device body while having a revolving shaft on the proximal end side and supported rotatably, a guide member having a first guide face moving in contact with the link member when the opening and closing door moves to the close position, and a second guide face moving in contact with the link member when the opening and closing door moves to the open position, and a changeover member for guiding the link member from the first guide face to the second guide face.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an opening / closing mechanism and an image forming apparatus.

  From the sheet conveyance path for conveying the sheet to be sent to the image forming unit, the fixed guide plate provided along the one surface of the sheet conveyance path, and the state along the other surface of the sheet conveyance path and from the fixed guide plate A movable guide plate that is rotatably provided to be separated, a drive roller that is provided on the fixed guide plate side, and a drive that is provided in a state that can be rotationally displaced integrally with the movable guide plate side and the movable guide plate. A driven roller that can be brought into and out of contact with the roller, a door body that is rotatably provided facing the movable guide plate, and the movable guide plate conveys paper in conjunction with the opening and closing operation of the door body. A connecting member that connects the two so as to be rotationally displaced to a position along the road and a spaced position, and is slightly movable in the direction of the fixed guide plate integrally with the movable guide plate when the door is closed, and the connecting member Connected to the door and the door closed Oite driven Russia - la is driven Russia - the sheet feeding apparatus is known which is provided a biasing member for biasing the coupling member in rolling contact direction, against La (Patent Document 1).

  An apparatus main body, an opening / closing member provided on the apparatus main body so as to be openable / closable, and a fixing lever that is rotatably supported by either one of the apparatus main body or the opening / closing member via a support shaft and fixes the closed state of the opening / closing member And a holding means for movably holding the support shaft, and a connected portion to which the fixing lever is connected when the opening / closing member is closed, provided on the apparatus body or the opening / closing member on the other side of the side on which the fixing lever is supported And an elastic member for positioning the rotation angle position of the fixing lever at one of a fixed position where the opening / closing member is fixed by connecting to the connected portion and a standby position where the fixing member can be connected to the connected portion. When the open / close member is closed from the state where the open / close member is separated from the apparatus body and the open / close member is closed from the state where the open / close member is in the fixed position, Linkable to And connecting means for moving the location, also known opening and closing mechanism having a, a shaft biasing means for biasing the position corresponding to the standby position of the locking lever supporting shaft (Patent Document 2).

Japanese Patent Laid-Open No. 5-208737 JP 2011-53281 A

  SUMMARY An advantage of some aspects of the invention is that it provides an opening / closing mechanism and an image forming apparatus capable of reducing an operation force when opening / closing an opening / closing door.

In order to solve the above-described problem, the opening / closing mechanism according to claim 1 is:
An open / close door that is rotatably supported so as to be movable between a closed position that covers the opening of the apparatus main body and an open position that opens the opening;
A link member rotatably supported by a rotation shaft provided in the apparatus main body,
A first guide surface that moves while contacting the link member when the opening and closing door moves to the closed position, and a first guide surface that moves while contacting the link member when the opening and closing door moves to the open position. A guide member having two guide surfaces;
A switching member for guiding the link member from the first guide surface to the second guide surface,
It is characterized by that.

The invention according to claim 2 is the opening and closing mechanism according to claim 1,
The link member rotates about the rotation axis while receiving a rotation moment with an elastic member stretched on the tip side.
It is characterized by that.

The invention according to claim 3 is the opening / closing mechanism according to claim 1 or 2,
When the opening / closing door moves from the open position to the closed position, the link member has the tip side on which the elastic member is stretched at least at the terminal portion of the first guide surface, and the top dead center is exceeded. The direction of the rotational moment is reversed, and the guide member is pulled in the moving direction of the door.
It is characterized by that.

The invention according to claim 4 is the opening and closing mechanism according to any one of claims 1 to 3,
The switching member comes into contact with the link member whose direction of the rotational moment is reversed at least at the end portion of the first guide surface and swings while receiving the rotational moment of the link member, thereby moving the link member to the first direction. 2 guide to the guide surface,
It is characterized by

The invention according to claim 5 is the opening and closing mechanism according to any one of claims 1 to 4,
The second guide surface has a first guide part having a gentle inclination angle along the moving direction of the door and a steeper inclination angle than the first guide part in a direction intersecting the moving direction of the door. When the open / close door moves from the closed position to the open position, the link member rotates along the first guide portion and moves to the open position of the open / close door. The tip side on which the elastic member is stretched by rotating along the second guide part exceeds the top dead center, and the direction of the rotational moment is reversed.
It is characterized by that.

In order to solve the above-mentioned problem, an image forming apparatus according to claim 6,
An image forming unit for forming an image on paper;
A paper transport unit that transports the paper toward the image forming unit;
An opening / closing mechanism according to any one of claims 1 to 5.
It is characterized by that.

According to the first and sixth aspects of the invention, it is possible to reduce the operating force for closing the opening / closing door and to suppress an increase in the operating force for opening / closing the opening / closing door.
According to invention of Claim 2, the rotation direction of a link member can be switched.
According to the third aspect of the present invention, it is possible to reduce the operating force for closing the door.
According to the fourth aspect of the present invention, the pulling force of the open / close door can be received from the link member.
According to the fifth aspect of the present invention, it is possible to suppress an increase in the operating force for opening the door.

2 is a schematic vertical sectional view showing an internal configuration of the image forming apparatus. FIG. It is a cross-sectional schematic diagram showing the internal configuration of the paper transport unit and paper transport. It is a cross-sectional schematic diagram of a paper transport unit. (A) is a schematic diagram showing the positional relationship between the open / close door and the paper transport unit when the paper transport unit is opened, and (b) is a schematic diagram of the paper transport unit showing the movement of the paper transport unit by the closing operation of the open / close door. is there. (A) is a schematic diagram which shows the structure of an opening-and-closing mechanism, (b) is a schematic diagram which shows the opening-and-closing mechanism of the state in which the opening-and-closing door is locked in the closed position. It is a schematic diagram explaining the drawing-in operation | movement of the opening / closing door by a link member when an opening / closing door moves to a closed position. It is a schematic diagram explaining the return operation | movement of a link member when an opening-and-closing door moves to an open position.

Next, the present invention will be described in more detail with reference to the drawings with reference to embodiments and specific examples. However, the present invention is not limited to these embodiments and specific examples.
Also, in the description using the following drawings, it should be noted that the drawings are schematic and the ratio of each dimension and the like are different from the actual ones, and are necessary for the description for easy understanding. Illustrations other than the members are omitted as appropriate.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, and the up-down direction is the Z-axis direction.

(1) Overall Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic longitudinal sectional view showing the internal configuration of the image forming apparatus 1 according to this embodiment.
Hereinafter, the overall configuration and operation of the image forming apparatus 1 will be described with reference to the drawings.

  The image forming apparatus 1 is configured to include a control device 10, a paper feeding device 20, a photosensitive unit 30, a developing unit 40, a transfer unit 50, a paper transport unit 60, a fixing unit 70, and the like in a housing 100. . On the upper surface (Z direction) of the image forming apparatus 1, there is formed a discharge tray portion T for discharging and storing a sheet on which an image is recorded. Further, on the side surface (−X direction) of the image forming apparatus 1, an opening / closing door 210 that opens the inside of the image forming apparatus 1 is rotatably supported when removing or inspecting when the paper P is jammed. Has been.

  The control device 10 includes an image forming device control unit 11 that controls the operation of the image forming device 1, a controller unit 12 that prepares image data according to a print processing request, an exposure control unit 13 that controls lighting of the exposure head LH, It has a power supply device 14 and the like. The power supply device 14 applies a high voltage to a charging roller 32, a developing roller 42, a primary transfer roller 52, a secondary transfer roller 62 and the like, which will be described later, and includes an exposure head LH, a paper feeding device 20, a fixing unit 70, and the like. Power is supplied to each sensor.

  The controller unit 12 converts print information input from an external information transmitting apparatus (for example, a personal computer) into image information for forming a latent image and outputs a drive signal to the exposure head LH at a preset timing. . The exposure head LH of the present embodiment is configured by an LED head in which a plurality of light emitting elements (LEDs) are linearly arranged along the main scanning direction.

  A paper feeding device 20 is provided at the bottom of the image forming apparatus 1. The sheet feeding device 20 includes a sheet stacking plate 21, and a plurality of sheets P as recording media are stacked on the upper surface of the sheet stacking plate 21. The sheets P stacked on the sheet stacking plate 21 are drawn forward (−X direction) one by one from the upper side by the sheet pulling portion 22, and then are driven by a driving roller 25 a and a driven roller 25 b via a sheet guide guide 23. To the nip portion of the registration roller pair 25 made of

  The photosensitive unit 30 is provided in parallel above the sheet feeding device 20 (Z direction) and includes a photosensitive drum 31. Around the photosensitive drum 31, a charging roller 32, an exposure head LH, a developing unit 40, a primary transfer roller 52, and a cleaning blade 33 are arranged along the rotation direction.

The developing unit 40 has a developing housing 41 in which a developer is accommodated. In the developing housing 41, a developing roller 42 disposed to face the photosensitive drum 31, and a pair of augers 44 that stir and convey the developer to the developing roller 42 side obliquely below the back side of the developing roller 42, 45 is arranged. A layer regulating member 46 that regulates the layer thickness of the developer is disposed in proximity to the developing roller 42.
Each of the developing units 40 is configured in substantially the same manner except for the developer contained in the developing housing 41, and each forms a toner image of yellow (Y), magenta (M), cyan (C), and black (K). To do.

  The surface of the rotating photosensitive drum 31 is charged by the charging roller 32, and an electrostatic latent image is formed by the latent image forming light emitted from the exposure head LH. The electrostatic latent image formed on the photosensitive drum 31 is developed as a toner image by the developing roller 42.

  The transfer unit 50 includes an intermediate transfer belt 51 to which each color toner image formed on the photoconductive drum 31 of each photoconductor unit 30 is transferred, and each color toner image formed on each photoconductor unit 30 to the intermediate transfer belt. A primary transfer roller 52 that sequentially transfers (primary transfer) to 51 is provided. Further, an intermediate transfer belt cleaner 54 that removes residual toner adhering to the intermediate transfer belt 51 is provided.

  The paper transport unit 60 corrects the posture of the paper P fed from the paper feeding device 20 and sends the paper P to the secondary transfer portion TR in accordance with the secondary transfer timing, and a driven roller 25b of the registration roller pair 25, A secondary transfer roller 62 is provided that collectively transfers (secondary transfer) each color toner image transferred onto the intermediate transfer belt 51 onto a sheet P as a recording medium. Further, the sheet P on which the transferred toner image is held is guided to the fixing nip portion N of the fixing unit 70 via the conveyance guide 65.

  Each color toner image formed on the photosensitive drum 31 of each photosensitive unit 30 is transferred to an intermediate transfer belt by a primary transfer roller 52 to which a predetermined transfer voltage is applied from a power supply device 14 or the like controlled by the image forming apparatus control unit 11. Electrostatic transfer (primary transfer) is sequentially performed on 51, and a superimposed toner image in which toners of respective colors are superimposed is formed.

The superimposed toner image on the intermediate transfer belt 51 is conveyed to the secondary transfer unit TR as the intermediate transfer belt 51 moves. When the superimposed toner image is conveyed to the secondary transfer unit TR, the paper P is supplied from the registration roller pair 25 to the secondary transfer unit TR in accordance with the timing.
A predetermined transfer voltage is applied to the secondary transfer roller 62 from the power supply device 14 or the like controlled by the image forming apparatus control unit 11, and the sheet P sent out from the registration roller pair 25 is applied to the intermediate transfer belt 51. Multiple toner images are batch transferred.

  Residual toner on the surface of the photosensitive drum 31 is removed by the cleaning blade 33 and collected in a waste toner collection container (not shown). The surface of the photosensitive drum 31 is recharged by the charging roller 32.

  The fixing unit 70 includes a heating module 71 and a pressure module 72, and a fixing nip portion N (fixing area) is formed by a pressure contact area between the heating module 71 and the pressure module 72. The sheet P on which the toner image is transferred in the secondary transfer unit TR is transported to the fixing unit 70 via the transport guide 65 in a state where the toner image is not fixed. The toner image is fixed on the sheet P conveyed to the fixing unit 70 by a pair of heating module 71 and pressure module 72 by the action of heating and pressure bonding.

  The sheet P on which the fixing toner image is formed is discharged from the discharge roller pair 79 to the discharge tray portion T on the upper surface of the image forming apparatus 1 via the conveyance roller pair 78. In the case of duplex printing, when the rear end of the sheet P on which the surface is fixed passes through the transport roller pair 78, the discharge roller pair 79 is driven reversely so that the reverse transport formed in the open / close door 210 is reversed. From the path, the sheet is conveyed to the registration roller pair 25 and image formation is performed on the back surface.

(2) Configuration and operation of the paper transport unit FIG. 2 is a schematic cross-sectional view showing the internal configuration of the paper transport unit and paper transport, FIG. 3 is a schematic cross-sectional view of the paper transport unit 60, and FIG. FIG. 5B is a schematic diagram showing the positional relationship between the open / close door 210 and the paper transport unit 60 when opened, and FIG. 5B is a schematic diagram of the paper transport unit showing the movement of the paper transport unit 60 due to the closing operation of the open / close door 210. ) Is a schematic diagram showing a configuration of the opening / closing mechanism 200, and FIG. 9B is a schematic diagram showing the opening / closing mechanism 200 in a state where the opening / closing door 210 is locked at the closed position.
Hereinafter, the configuration and operation of the paper transport unit of the image forming apparatus 1 will be described with reference to the drawings.

  The paper transport unit includes a housing 100, an opening / closing mechanism 200 including an opening / closing door 210, and a paper transport unit 60.

(2.1) Housing The housing 100 has an opening on the side (−X direction), and accommodates the photoreceptor unit 30, the developing unit 40, the transfer unit 50, and the like.
A bearing 101 serving as a rotation center of the opening / closing door 210 is formed at the lower end on the opening side of the housing 100 and rotatably supports a rotation shaft 211 of the opening / closing door 210 described later.

Lock pins 103 are provided at the upper part on the opening side of the housing 100 so as to protrude in a direction intersecting with the opening / closing direction of the opening / closing door 210.
And the recessed part 215a of the latch lever 215 rotatably provided above the opening-and-closing door 210 fits, and the opening-and-closing door 210 is fixed to the housing | casing 100 in the state which obstruct | occluded the opening part.

(2.2) Opening / Closing Door The opening / closing door 210 rotatably supports the paper transport unit 60 and is closed with the rotation shaft 211 supported by the bearing portion 101 of the housing 100 to block the opening of the housing 100. Rotating movement between the position and the open position that opens the opening.
On the inner surface of the opening / closing door 210 facing the housing 100, the outer side which is one of the reverse conveyance paths through which the paper P whose conveyance direction has been reversed after the surface has been fixed passes again before joining the registration roller pair 25 again. A conveyance guide 213 is formed.

The outer conveyance guide 213 forms a reverse conveyance path while maintaining a predetermined gap with the inner conveyance guide 631 formed in the paper conveyance unit 60.
A plurality of conveyance roller pairs 120, 130, and 140 are arranged in the reverse conveyance path, and driving-side conveyance rollers 120 a, 130 a, and 140 a that constitute the conveyance roller pairs 120, 130, and 140 are arranged in the outer conveyance guide 213. ing.

(2.3) Paper Conveying Unit The paper conveying unit 60 includes a registration unit unit 610, a secondary transfer unit unit 620, and a duplex unit unit 630.

The registration unit 610 includes a first paper guide guide 611, a driven roller 25 b of the registration roller pair 25, and a second paper guide guide 612. The driving roller 25a of the registration roller pair 25 is disposed on the apparatus main body side.
The first sheet guide 611 guides the sheet P fed from the sheet feeding device 20 and the sheet P conveyed through the duplex unit 630 to the nip portion of the registration roller pair 25. The second sheet guide 612 guides the sheet P fed out from the registration roller pair 25 with its posture corrected to the secondary transfer unit TR.

  The secondary transfer unit section 620 includes a secondary transfer roller 62 and a conveyance guide 65, and a secondary transfer roller that is urged toward the intermediate transfer belt 51 to the sheet P that is fed in accordance with the secondary transfer timing. At 62, the toner image held on the intermediate transfer belt 51 is batch transferred (secondary transfer). The sheet P on which the toner image has been transferred is guided to the fixing nip N of the fixing unit 70 via the conveyance guide 65.

The duplex unit 630 has an inner conveyance guide 631 that constitutes the other surface side of the reverse conveyance path so as to face the outer conveyance guide 213 formed on the inner surface side of the opening / closing door 210, and is used for printing paper P to be printed on both sides. It is conveyed to the registration roller pair 25.
In the inner conveyance guide 631, a pinch roller 130 b of the conveyance roller pair 130 and a pinch roller 140 b of the conveyance roller pair 140 are rotatably disposed.

  Further, a pair of left and right rotating shafts 632 are formed on the lower side of the inner conveyance guide 631. The rotary shaft portion 632 is fitted into a bearing portion 212 formed on both side plates 210 a of the opening / closing door 210, and the paper transport unit 60 is rotatably supported with respect to the opening / closing door 210.

  As shown in FIG. 4, one end of the compression coil spring S is fixed to both sides of the inner conveyance guide 631, and the other end is fixed to the inner surface side of the opening / closing door 210 facing the inner conveyance guide 631. Thereby, when the door 210 is fixed at the closed position, the urging force of the compression coil spring S acts between the paper transport unit 60 and the door 210.

Therefore, when the opening / closing door 210 moves to the open position, the paper transport unit 60 rotates with the movement of the opening / closing door 210, the nip of the registration roller pair 25 is released, and the secondary transfer section TR The nip between the transfer roller 62 and the intermediate transfer belt 51 is also released.
Then, the inner conveyance guide 631 and the outer conveyance guide 113 forming the reverse conveyance path are released from each other by the urging force of the compression coil spring S, and the nip of the conveyance roller pair 120, 130, 140 is also released.

When returning the open / close door 210 from the open position to the closed position, the open / close door 210 is rotated to the housing 100 side.
As the opening / closing door 210 rotates toward the housing 100, the paper transport unit 60 also rotates toward the housing 100, and the nip of the registration roller pair 25 and the nip of the secondary transfer roller 62 in the secondary transfer portion TR. The recess 215a of the latch lever 215 is fitted into the lock pin 103 and fixed in a state where the reaction force is received.

(2.4) Opening / Closing Mechanism The opening / closing mechanism 200 is configured to apply the rotational moment M to the opening / closing door 210, the guide member 220 disposed in the opening / closing door 210, the switching member 230, the link member 240 disposed in the housing 100, and the link member 240. It is comprised from the tension coil spring 250 as an example of the elastic member to provide.

  The guide member 220 is disposed above the open / close door 210 and fixed below the latch lever 215. As shown in FIG. 5A, the guide member 220 includes a first guide surface 221 that moves while contacting the link member 240 described later when the door 210 is moved to the closed position, and the door 210 is opened. It has the 2nd guide surface 222 which moves, contacting the link member 240, when moving to a position.

  The first guide surface 221 forms a trajectory that moves obliquely downward from the start end 221a to the end 221b that receives the stud 242 of the link member 240 when the open / close door 210 moves to the closed position.

  The second guide surface 222 is formed below the first guide surface 221, and intersects the moving direction of the opening / closing door 210 with the first guiding portion 222 </ b> A having a gentle inclination angle along the moving direction of the opening / closing door 210. The second guide part 222B has a steeper inclination angle than the first guide part 222A in the direction, and forms a movement trajectory that moves while contacting the stud 242 of the link member 240 when the door 210 moves to the open position. ing.

The switching member 230 has arm portions 232 protruding on both sides of the rotation shaft 231, and is rotatably provided below the terminal end 221 b of the first guide surface 221 and above the start end 222 a of the second guide surface 222. ing.
When the stud 242 of the link member 240 that rotates by the movement of the first guide surface 221 exceeds the top dead center at the terminal end 221b of the first guide surface 221, the switching member 230 has one arm portion 232 linked. The rotation moment M which the member 240 reversed is received. As a result, a pulling force toward the housing 100 acts on the opening / closing door 210, and an operation force to the closing position of the opening / closing door 210 is reduced.

  A stopper 225 is formed below the rotation shaft 231 of the switching member 230 and contacts the arm portion 232 of the switching member 230 to restrict the rotation of the switching member 230.

  The link member 240 is supported by the housing 100 so that the base end side 240a is the rotation shaft 104 and is rotatable. The distal end side 240 b has a stud 242 that protrudes in a direction intersecting the rotation direction, and a tension coil spring 250 is stretched around the stud 242. As a result, the link member 240 rotates clockwise or counterclockwise with the position where the tension direction of the tension coil spring 250 and the virtual line c1 connecting the rotation shaft 104 and the stud 242 overlap on the same straight line as the top dead center. The rotation moment M by the tension coil spring 250 is reversed and applied (see the arrow M in FIGS. 5A and 5B).

(3) Opening / Closing Operation of Opening / Closing Door FIG. 6 is a schematic diagram for explaining the retracting operation of the opening / closing door 210 by the link member 240 when the opening / closing door 210 moves to the closed position, and FIG. 7 shows the opening / closing door 210 moving to the open position. It is a schematic diagram explaining the return operation | movement of the link member 240 at the time. Hereinafter, the operation of the opening / closing mechanism 200 will be described with reference to the drawings.

When returning the open / close door 210 from the open position to the closed position, the user rotates the open / close door 210 to the housing 100 side.
As the opening / closing door 210 rotates toward the housing 100, the guide member 220 fixed to the opening / closing door 210 also rotates toward the housing 100, and the stud 242 of the link member 240 disposed in the housing 100 moves. It contacts from the start end 221a side of the 1st guide surface 221 (refer Fig.6 (a)).
When the door 210 is further rotated to the closed position, the stud 242 of the link member 240 rotates along the movement locus of the first guide surface 221 and reaches the top dead center at the end 221b of the first guide surface 221. It will be in the state where the rotational moment M does not act (refer FIG.6 (b)).

Then, the link member 240 whose stud 242 has reached the top dead center contacts the arm portion 232 of the switching member 230 and rotates the switching member 230 at the same time as the direction of the rotational moment M is reversed.
When the rotation of the switching member 230 is restricted by the stopper 225, the switching member 230 receives the rotational moment M of the link member 240 whose direction of the rotational moment M is reversed, and the opening / closing door 210 receives the rotational moment M of the link member 240 in the closed position direction. The pull-in force F by (see FIG. 6C).
Thereby, a part of the reaction force caused by the nip of the registration roller pair 25 and the nip of the secondary transfer roller 62 can be offset to reduce the operating force.

  When the opening / closing door 210 is further rotated to the closed position, the stud 242 of the link member 240 passes through the arm portion 232 of the switching member 230, the switching member 230 returns to the standby position, and the link member 240 is moved to the closed position. To reach. Then, the recess 215a of the latch lever 215 fits into the lock pin 103 provided in the housing 100, and the open / close door 210 is fixed in the closed position (see FIG. 5B).

  When the door 210 is moved from the closed position to the open position, the user lifts the latch lever 215 provided above the door 210 to release the engagement with the lock pin 103 provided on the housing 100. The opening / closing door 210 is rotated and moved to the side of the main body of the image forming apparatus 1 (the −X direction in FIG. 1).

  When the rotational movement of the opening / closing door 210 is started, the stud 242 of the link member 240 rotates along the first guide portion 222 </ b> A of the second guide surface 222 of the guide member 220. Since the first guide portion 222A of the second guide surface 222 has a gentle inclination angle along the moving direction of the opening / closing door 210, the first guide portion 222A is in the same direction as the direction of action of the pull-in force F due to the rotational moment M (see FIG. 7 (a)), an increase in the operating force of the opening operation of the door 210 is suppressed.

When the opening and closing door 210 is further rotated, the stud 242 of the link member 240 rotates while reaching the top dead center by rotating along the second guide part 222B having a steeper inclination angle than the first guide part 222A. The moment M does not act (see FIG. 7B).
Then, along with the rotational movement of the opening / closing door 210, the link member 240 reverses the direction of the rotational moment M and returns to the standby position that accepts the rotational movement of the opening / closing door 210 to the closed position (see FIG. 7C).

  In this way, when returning the open / close door 210 from the opened open position to the closed position, the link member 240 disposed in the housing 100 rotates along the first guide surface 221 of the guide member 220 while rotating the first. The direction of the rotational moment M is reversed at the terminal end 221b of the guide surface 221, and the pulling force F by the link member 240 acts on the open / close door 210 to reduce the operating force.

  On the other hand, when the opening / closing door 210 is moved from the closed position to the open position, the link member 240 that assists the closing operation of the opening / closing door 210 has a gentle inclination angle of the second guide surface 222 different from that during the closing operation. By rotating along the first guide part 222A, the increase in the operating force during the opening operation is suppressed.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Control apparatus 20 ... Paper feed apparatus 25 ... Registration roller pair 30 ... Photoconductor unit 40 ... Development unit 50 ... Transfer unit 60 ... Sheet transport unit 610: Registration unit section 611: First sheet guide guide 612: Second sheet guide guide 620: Secondary transfer unit section 630: Duplex unit section 631: Inside transport Guide 62 ... Secondary transfer roller 70 ... Fixing unit 100 ... Housing 103 ... Lock pin 104 ... Rotating shaft 210 ... Opening / closing door 213 ... Outer conveyance guide 215 ... Latch lever 220 ... guide member 221 ... first guide surface 222 ... second guide surface 225 ... stopper 230 ... switching member 240 ... link member 24 · Studs 250 ... the tension coil spring (link member 240)
S: Compression coil spring (paper transport unit 60)

Claims (6)

An open / close door that is rotatably supported so as to be movable between a closed position that covers the opening of the apparatus main body and an open position that opens the opening;
A link member rotatably supported by a rotation shaft provided in the apparatus main body,
A first guide surface that moves while contacting the link member when the opening and closing door moves to the closed position, and a first guide surface that moves while contacting the link member when the opening and closing door moves to the open position. A guide member having two guide surfaces;
A switching member for guiding the link member from the first guide surface to the second guide surface,
An opening / closing mechanism characterized by that. The link member rotates about the rotation axis while receiving a rotation moment with an elastic member stretched on the tip side.
The opening / closing mechanism according to claim 1. When the opening / closing door moves from the open position to the closed position, the link member has the tip side on which the elastic member is stretched at least at the terminal portion of the first guide surface, and the top dead center is exceeded. The direction of the rotational moment is reversed, and the guide member is pulled in the moving direction of the door.
The opening / closing mechanism according to claim 1 or 2. The switching member comes into contact with the link member whose direction of the rotational moment is reversed at least at the end portion of the first guide surface and swings while receiving the rotational moment of the link member, thereby moving the link member to the first direction. 2 guide to the guide surface,
The opening / closing mechanism according to any one of claims 1 to 3. The second guide surface has a first guide part having a gentle inclination angle along the moving direction of the door and a steeper inclination angle than the first guide part in a direction intersecting the moving direction of the door. When the open / close door moves from the closed position to the open position, the link member rotates along the first guide portion and moves to the open position of the open / close door. The tip side on which the elastic member is stretched by rotating along the second guide part exceeds the top dead center, and the direction of the rotational moment is reversed.
The opening / closing mechanism according to any one of claims 1 to 4, wherein the opening / closing mechanism is provided. An image forming unit for forming an image on paper;
A paper transport unit that transports the paper toward the image forming unit;
An opening / closing mechanism according to any one of claims 1 to 5.
An image forming apparatus.

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