JP2010197502A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus with satisfactory operability when starting opening of a door while suppressing occurrence of noise and a shock at the end of opening of the door with a simple configuration by combining opening operation assitance when starting of opening of the door and a damper function at the end of opening of the door in one spring. <P>SOLUTION: The image forming apparatus has one spring member (door unit pressurization spring 85) which energizes a door opening/closing link member 86 so that rotational moment in an opening direction acts when a position of a door center is on a closing position side from a first position which becomes perpendicularly upward of a rotary shaft of a door unit D, and rotational moment in a closing direction acts when the position of the door center is on an opening position side from the first position, wherein the rotational moment in the opening direction which acts by the spring member is larger than the rotational moment in the closing direction which acts by door self-weight when the door unit D is located at a closed position, and the rotational moment in the closing direction which acts by the spring member is larger than the rotational moment in the opening direction which acts by the door self-weight when the door unit D is located at the opening position. <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.

  Conventionally, an electrophotographic image forming apparatus that forms an image on a recording material using an electrophotographic image forming process employs the following cartridge system. That is, the electrophotographic photosensitive member and the process means acting on the electrophotographic photosensitive member are integrated into a cartridge so that the cartridge can be attached to and detached from the main body of the electrophotographic image forming apparatus.

  According to this cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved. For this reason, this cartridge system is widely used in electrophotographic image forming apparatuses.

  Some electrophotographic image forming apparatuses using such a cartridge system have a mechanism for automatically opening and closing a process cartridge attaching / detaching door in order to improve user operability. As an example, there is an apparatus that includes a lock mechanism that locks the process cartridge attachment / detachment door in a closed state, and further includes a spring that constantly urges the locked open / closed body in the opening direction. In such an apparatus, when the locking means is released, the opening / closing body is automatically opened by the spring force of the spring member.

  By using such means, even a user unfamiliar with the operation of a printer or the like can easily operate the opening / closing unit of the image forming apparatus, and the opening / closing operation unit such as a door has a high-class feeling. Can be made.

  Patent Document 1 discloses the following technique in the electrophotographic image forming apparatus provided with the mechanism for automatically opening and closing the process cartridge attaching / detaching door as described above. It prevents deflection and creep of the resin support member caused by the spring that normally biases the opening and closing body, and prevents malfunction of the opening and closing body due to deformation and creep phenomenon of the resin support member. is there. Patent Document 2 discloses a configuration in which a backup spring of a damper means acts on the opening / closing cover in the closing direction of the opening / closing cover during the opening / closing operation of the opening / closing cover.

JP-A-9-26736 Japanese Patent Laid-Open No. 11-84982

  However, in the configuration described in Patent Document 1, since the opening / closing body is always urged in the opening direction, when the opening / closing body such as the door is fully opened at the position where the opening / closing operation is completed, the collision occurs with the parts on the apparatus main body side. However, there is a concern that noise and shock that are uncomfortable for the user may be generated.

  Further, in the configuration described in Patent Document 2, the backup spring acts in the closing direction of the opening / closing cover at the end of opening of the opening / closing cover and exhibits a damper effect. At the beginning of opening, the spring force is a resistance of the opening operation of the user. Therefore, there is a concern that the operability of the user is impaired.

  The object of the present invention is to reduce the generation of noise and impact at the end of the door opening with a simple structure by combining the opening action assist at the start of the door opening and the damper function at the end of the door opening. On the other hand, it is to provide a device with good operability when the door is opened.

In order to achieve the above object, the present invention provides:
An opening / closing member provided rotatably and opened / closed with respect to the apparatus main body;
A locking mechanism for locking the opening / closing member to the apparatus main body in the closed position;
Have
When the opening / closing member rotates in the opening direction from the closed position, the opening / closing member opens to a position rotated beyond a first position where the position of the center of gravity of the opening / closing member is vertically above the rotation axis of the opening / closing member. In the image forming apparatus in which the rotation direction is switched by the weight of the opening / closing member with the first position as a boundary,
A moving member provided so as to be interlocked with an opening / closing operation of the opening / closing member; a second position located when the opening / closing member takes the closed position; and a position when the opening / closing member takes the open position. A moving member movably provided between the third position and
One spring member having one end attached to the apparatus main body and the other end attached to the moving member,
When the position of the center of gravity of the opening / closing member is closer to the closed position than the first position, the moving member is attached in the direction of the third position so that a rotational moment in the opening direction acts on the opening / closing member. Vigorously,
When the position of the center of gravity of the opening / closing member is closer to the opening position than the first position, the moving member is attached in the direction of the second position so that a rotation moment in the closing direction acts on the opening / closing member. An energizing spring member;
Have
When the opening / closing member is located at the closed position, the spring member biases the moving member in the direction of the third position, rather than a rotational moment acting on the opening / closing member due to the weight of the opening / closing member. Therefore, the rotational moment in the opening direction acting on the opening / closing member is larger,
When the opening / closing member is located at the open position, the spring member biases the moving member toward the second position rather than the rotational moment in the opening direction that acts on the opening / closing member due to the weight of the opening / closing member. Thus, the magnitude of the biasing force of the spring member is set so that the rotational moment in the closing direction acting on the opening / closing member becomes larger.

  According to the present invention, one spring combines opening operation assistance at the start of door opening and a damper function at the end of door opening, thereby reducing noise and impact at the end of door opening with a simple configuration. On the other hand, it is possible to provide a device with good operability when the door is opened.

1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus to which the present invention can be applied. The schematic sectional drawing which shows the apparatus main body of the state in which the door unit opened in the Example. The schematic perspective view which shows the apparatus main body of the state in which the door unit opened in the Example. The schematic perspective view which shows the principal part of the apparatus main body of the state which opened the door unit in the Example. FIG. 3 is a schematic perspective view illustrating a process cartridge mounting portion of the apparatus main body in the embodiment. FIG. 2 is a schematic perspective view showing a process cartridge in the embodiment. FIG. 2 is a schematic perspective view showing a process cartridge in the embodiment. The schematic perspective view which shows the frame structure of a door unit in an Example. Schematic which showed the structure of the door lock and the lock release part in the Example. The figure which showed typically the principal part of the image forming apparatus in order to demonstrate operation | movement of a door unit pressurization spring in an Example. The figure for demonstrating the moment by the dead weight of a door unit, and the moment by a door unit pressurization spring in an Example. The figure which shows the relationship between the moment by the dead weight of a door unit, the moment by a door unit pressurization part, and a rotation angle in an Example.

  DETAILED DESCRIPTION Exemplary embodiments for carrying out the present invention will be 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.

  Here, an electrophotographic image forming apparatus as an image forming apparatus to which the present invention is applicable forms an image on a recording material using an electrophotographic image forming process, and includes the following apparatuses. Examples thereof include an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer, etc.), an electrophotographic facsimile apparatus, an electrophotographic word processor, and the like. The opening / closing member to which the present invention can be applied includes, for example, a toner cartridge that is detachable from the main body of the image forming apparatus, an access door to a recording material stacking unit that is opened and closed by the user when the recording material is replenished, and a service unit. An access door at the time of replacement is mentioned. Further, an access door when attaching or removing the accessory, an access door when the user cleans the inside of the electrophotographic image forming apparatus main body, an opening / closing portion during JAM processing, and the like can be given.

(Overall configuration of image forming apparatus)
FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus that forms an image by an electrophotographic process to which the present invention can be applied.

  The image forming apparatus according to the first exemplary embodiment includes an exposure apparatus 2 as an optical unit, a process cartridge P having a developing unit, and an electrical unit 30 that controls driving of the apparatus. The exposure apparatus 2 as optical means includes a laser diode (not shown) as a light source, a polygon mirror 21, and a reflection mirror 22.

  Further, the image forming apparatus according to the first embodiment includes the manual feed tray 4 and the feeding cassettes 5 and 6 as the recording material S stacking means, and a plurality of recording materials are stacked on these stacking means. Further, feeding rollers 7, 8 and 9 are provided for separating and transporting the stacked recording materials one by one, and a registration roller pair 10 for transporting the separated recording materials is provided. An inner discharge roller pair 16 and an outer discharge roller pair 17 for discharging the recording material S on which an image is formed are provided on the downstream side in the transport direction.

  A process for forming an image on the recording material S in the image forming apparatus main body (hereinafter referred to as the apparatus main body) 1 configured as described above will be described below.

  When an image formation start signal is input at a signal input unit (not shown), the recording material S in the manual feed tray 4 and the feed cassettes 5 and 6 are fed by feed rollers 7, 8, and 9 provided respectively. Sent. At this time, since the feeding rollers 7, 8, and 9 employ a frictional separation system that separates the recording materials one by one, the recording materials are separated and fed one by one by these rollers. The recording material S fed by the feeding rollers 7, 8, 9 is abutted against the nip portion of the registration roller pair 10 whose rotation is stopped. Then, the registration roller pair 10 is driven at a predetermined timing, and the skew of the recording material S is corrected in the registration roller pair 10.

  On the other hand, in the exposure apparatus 2 as an optical means, laser light emitted from a laser diode as a light source is scanned by the polygon mirror 21 and irradiated onto the surface of the photosensitive drum 31. Thereby, an electrostatic latent image is formed on the surface of the photosensitive drum 31. Then, toner as a developer is supplied to the electrostatic latent image formed on the surface of the photosensitive drum 31 from the developing means accommodated in the process cartridge P, so that the toner on the surface of the photosensitive drum 31 is supplied. An image is formed.

  The recording material S is corrected in skew by the registration roller pair 10 and then conveyed to a conveyance nip portion formed by the photosensitive drum 31 and the transfer roller 11 with timing. The recording material S is charged by a transfer charger (not shown), and then the toner image is transferred at the conveyance nip portion.

  The recording material S to which the toner image is transferred is conveyed along the conveyance guide 12 to the fixing device 13, and the image is permanently fixed on the recording material S. The fixing device 13 according to the first exemplary embodiment includes a pressure roller 14 and a fixing roller 15, and a heater (not shown) is provided inside the fixing roller 15. When the image is fixed, a heating heater applies heat to the image forming surface of the recording material S while the recording material S is nipped and conveyed by the nip portion formed by the pressure roller 14 and the fixing roller 15. The image can be fixed on the recording material S by applying heat to the image formed on the recording material S at the nip portion and further applying pressure by the pressure roller 14. The recording material S on which the image is fixed in the fixing device 13 is discharged to the discharge tray 18 by the inner discharge roller pair 16 and the outer discharge roller pair 17.

  Note that the image forming apparatus according to the present exemplary embodiment includes a double-sided print mode for performing double-sided printing on the recording material S and a single-sided print mode. In the single-sided print mode, the recording material S on which the image is fixed by the fixing device 13 is set to be conveyed to the discharge roller and discharged to the discharge tray 18 as it is. On the other hand, in the double-sided printing mode, the recording material S is conveyed to the refeed path 20 by the reverse driving of the pair of outer discharge rollers 17, and the recording material S is temporarily stacked on the intermediate tray 24. Then, the recording material S stacked on the intermediate tray 24 is conveyed again to the registration roller pair 10 by the refeed device 25, and thereafter an image is formed in the same manner as in the case of single-sided printing.

(Process cartridge mounting and dismounting part)
The attachment / detachment guide and attachment portion configuration of the process cartridge P will be described with reference to FIGS. FIG. 2 is a schematic view showing the apparatus main body 1 in a state where a cartridge access door (hereinafter referred to as a door unit) D as an opening / closing member that is rotatably provided and is opened and closed with respect to the apparatus main body 1 when the process cartridge is attached or detached. It is sectional drawing. FIG. 3 is a schematic perspective view showing the apparatus main body 1 with the door unit D opened. FIG. 4 is a schematic perspective view showing the main part of the apparatus main body 1 with the door unit D opened. FIG. 5 is a schematic perspective view showing a process cartridge mounting portion of the apparatus main body 1, and FIGS. 6 and 7 are schematic perspective views showing the process cartridge. Here, in the present embodiment, the vertical direction in the state where the apparatus main body 1 is installed is defined as the vertical direction. In FIG. 2, the right side is the front side (front side) of the apparatus body 1, and the left side is the rear side.

  The process cartridge P is detachably mounted on the cartridge mounting portion provided in the apparatus main body 1 by the user with the door unit D of the apparatus main body 1 opened. First, a guide member provided on the process cartridge P side will be described.

  A guide member on the process cartridge side is constituted by the outer diameters of the substantially cylindrical portions 70 and 71 on both outer side surfaces of the process cartridge P. Moreover, 72 and 73 which are rotation control contact parts are provided in the upper direction position at the time of mounting | wearing with the apparatus main body 1, and both ends, respectively.

  Next, the guide members 74 to 77 provided in the apparatus main body 1 will be described.

  The guide members 74 to 77 are configured to be inclined with respect to the mounting direction of the process cartridge P, and the substantially cylindrical portions 70 and 71 and the rotation restricting contact portions 72 and 73 of the process cartridge P are respectively inserted. The cartridge holding spring 78 attached to the inside of the apparatus main body 1 presses the outer peripheral portion of the substantially cylindrical portion 71 on one outer surface of the process cartridge P substantially vertically downward, so that the process cartridge P during the printing operation is pressed to the apparatus main body. 1 is held in the mounting position.

(Door unit configuration 1-frame configuration)
Next, the configuration of the door unit D that is opened and closed by the user when the process cartridge is attached / detached will be described with reference to FIGS. FIG. 8 is a schematic perspective view showing the frame configuration of the door unit D.

  The door unit D includes a door base frame 82, a door lock engaging portion (hereinafter referred to as an engaging portion) 83 (see FIG. 9), an exterior cover 84, and a manual feed tray 4. The door base frame 82 is attached to the main body frames 80a and 80b so as to be rotatable around the rotation support shafts (rotation shafts, rotation centers) 81, so that the door unit D can be opened and closed with respect to the apparatus body 1. It has become. The manual feed tray 4 can be opened and closed with respect to the door base frame 82, and also serves as an exterior cover (see FIG. 1).

  Reference numeral 85 denotes a door unit pressing spring as a spring member fixed to the main body frame side. The door unit pressure spring 85 is rotatably supported on the door unit D via a door opening / closing link member 86 as a moving member engaged with the main body frame 80a and an engagement portion 87 formed integrally with the door base frame 82. A biasing force is applied around the shaft 81. In this embodiment, as will be described later, the sum of rotational moments due to the door unit pressure spring 85 and the dead weight of the door is applied in the CW direction in FIG. Accordingly, when the door lock engaging portion (hereinafter referred to as engaging portion) 83 is released, the door unit D automatically rotates in the direction of CW to form a space as an access portion for the user to attach and detach the process cartridge. .

(Composition of door unit 2-structure of door lock and unlocking part)
FIG. 9 is a schematic diagram showing the configuration of the door lock portion and the lock release portion. FIGS. 9A and 9B are schematic perspective views of the vicinity of the cartridge access unit in a state where the door unit D is open. FIG. 9C is a top view for explaining the locked state of the door lock portion, and FIG. 9D is a front view for explaining the locked state of the door lock portion. FIG. 9E is a top view for explaining the unlocked state of the door lock unit, and FIG. 9F is a front view for explaining the unlocked state of the door lock unit.

  The engaging portion 83 provided on the door base frame 82 is engaged in a state where the lock engaging member 88 and the door unit D are closed (closed position). The door lock portion includes a lock engaging member 88, a door button 89, a spring 90, and a frame 91. The door lock portion and the engagement portion 83 correspond to a locking mechanism. Further, the door button 89 is formed with a tapered portion 92, and the lock engaging member 88 is formed with a tapered portion 93, and the tapered portion 92 and the tapered portion 93 are provided in contact with each other.

An operation of opening the door unit D is performed when the user pushes down the door button 89 on the door unit D and the door lock portion in the closed state. When the door button 89 is pushed down, the taper portion 92 formed integrally with the door button 89 presses the taper portion 93 on the lock engagement member 88 side, so that the lock engagement member 88 is shown in FIGS. Move to the right in (f). As a result, the lock engaging member 88 is separated from the engaging portion 83 of the door base frame 82.

  As a result, the door unit D can be rotated and automatically rotated by the moment generated by the door unit pressure spring 85. That is, by configuring in this way, the door unit D is automatically opened when the door button 89 is pressed, so that an operation method can be easily understood by a user who does not know how to open the door.

  When it is desired to close the door unit D, the opened door unit D is rotated in the CCW direction around the rotation support shaft 81 by a user operation. Here, a taper portion 94 is provided on the front end side (downstream side) of the door base frame 82 in the closing direction, and the taper portion 95 with which the taper portion 94 abuts the lock engagement member 88 when the door unit D is closed. Is provided. When the door unit D is closed, the taper portion 94 of the door base frame 82 comes into contact with the taper portion 95 of the lock engaging member 88, so that the lock portion is moved by the component of the door rotational force. ) Move right. When the door unit D is further rotated in the CCW direction and rotated to a position where the door unit D is fully closed, the lock engaging member 88 is inserted into the engaging portion 83 of the door base frame 82 by the force of the spring 90, and the door base frame 82 is inserted. And the lock engaging member 88 are engaged. As a result, the door unit D is locked to the apparatus main body 1 in the closed position. In the present embodiment, the above-described door locking and unlocking methods are used. However, other methods may be adopted as long as the door unit D can be held and opened in a closed position with respect to the main body frame. Good.

(Configuration of door unit 3-Configuration of door unit pressure spring)
The door unit of this embodiment is used as an urging means for automatically opening the door when the lock is released by the door unit pressurizing spring mechanism, and a brake means for gently opening the door before the door is fully opened. Used as

  When the door unit D of the present embodiment rotates in the opening direction from the closed position, the door unit D rotates beyond the door opening / closing position (first position) where the position of the center of gravity of the door unit D is vertically above the rotation support shaft 81. The open position of the door unit D exists at the position. Accordingly, there is a range where the rotational moment due to the weight of the door unit D acts in the CW direction and the CCW direction in a part of the movable range. In other words, the rotation direction in which the self-weight acts is switched at the door opening / closing position where the center of gravity of the door unit D is vertically above (vertically above) the rotation support shaft 81.

  For this reason, when the door unit D is in the closed state, and in a range (door closed position side) from when the door lock is released and the center of gravity of the door unit D reaches the rotation spindle 81 after the door starts to open. The following moment of rotation is given by the door unit pressure spring 85. That is, in order to automatically rotate the door, the door unit pressurizing spring 85 gives a rotational moment in the CW direction that exceeds the rotational moment in the CCW direction due to the action of the weight of the door unit D.

  Further, when the center of gravity of the door unit D is on the door opening side (door opening position side) from above the rotation support shaft 81, the moment due to the weight of the door unit D acts in the CW direction. Increases as the rotation angle increases. On the other hand, in this embodiment, a moment in the CCW direction is applied around the rotation support shaft 81 by the door unit pressing spring 85. In the open position of the door unit D or in the movable range near the door unit D, the door unit pressurizing spring 85 gives a rotational moment larger than the rotational moment in the CW direction due to the weight of the door unit D in the CCW direction. ing. Thus, by setting the magnitude of the spring force (biasing force, elastic force) of the door unit pressing spring 85, the door unit D resists an excessively large moment due to its own weight, and the door unit D is opened when the door unit D is opened. Can alleviate the impact of opening.

  FIG. 10 is a diagram schematically showing the main part of the image forming apparatus in order to explain the operation of the door unit pressure spring. FIG. 10A is a diagram showing a state where the door unit D is closed (a state where the door opening / closing link member 86 is located at the second position). FIG. 10B is a diagram illustrating a state where the center of gravity of the door unit D is vertically above the rotation support shaft 81 (a state where the door opening / closing link member 86 is located at the fourth position). FIG. 10C shows a state where the door unit D is fully opened (a state where the door opening / closing link member 86 is located at the third position). As shown in FIGS. 10A to 10C, one end of the door unit pressure spring 85 is locked to the spring hooking portion 101 of the main body frame 80a, and the other end thereof is attached to the mounting portion 86a of the door opening / closing link member 86. One tension coil spring attached. Here, in the second to fourth positions where the door opening / closing link member 86 is located, the distances from the rotation support shaft 81 (rotation center 105) are the third position, the fourth position, and the second position. It is provided to increase in order.

  The door opening / closing link member 86 is provided with a guide long hole shape (first long hole shape portion) 102. And the inner peripheral part of the long hole shape 102 is provided so that it may engage with the two guide pins 103 provided as an engaging part in the main body frame 80a. Here, the long hole shape 102 is a long hole whose longitudinal direction is the horizontal direction (one direction) when the door opening / closing link member 86 is attached to the apparatus main body 1 (when engaged with the main body frame 80a). It is provided in the shape. Thus, the door opening / closing link member 86 can reciprocate in the left-right direction (horizontal direction, one direction) in FIGS. 10A to 10C with respect to the apparatus main body 1. Further, the door opening / closing link member 86 has a long hole shape (second long shape) whose longitudinal direction is a direction intersecting the longitudinal direction of the long hole shape 102 (in the present embodiment, a direction orthogonal to the vertical direction). (Hole shape portion) 104. An engagement portion 87 formed integrally with the door base frame 82 is movably engaged with the long hole shape 104. With such a configuration, the door is formed. The rotation operation of the unit D is converted into a horizontal reciprocating motion of the door opening / closing link member 86, and the door opening / closing link member 86 moves (reciprocates) in the horizontal direction in conjunction with the opening / closing operation of the door unit D. .

  In the range from the closed position of the door unit D to the center of gravity of the door unit D reaching the rotation support shaft 81, the horizontal direction of the tension spring load of the door unit pressurizing spring 85 as shown in FIG. The component acts to the right. As a result, a moment in the CW direction due to the door unit pressing spring 85 is generated (acted) on the door unit D. Further, when the center of gravity of the door unit D is on the door opening side from above the rotation support shaft 81, as shown in FIG. 10C, the horizontal component of the tension spring load of the door unit pressurizing spring 85 is Acts to the left. Accordingly, a moment in the CCW direction is generated (acted) by the door unit pressurizing spring 85 in the door unit D. Further, as shown in FIG. 10C, when the rotational moment due to the dead weight of the door unit D becomes zero, that is, when the center of gravity of the door unit D is vertically above the rotation support shaft 81, the door unit pressurization is performed. The spring pressure (biasing force, elastic force) of the spring 85 is minimized. This is because the distance between the spring hooking portion 101 to which the door unit pressurizing spring 85 is attached and the attachment portion 86a of the door opening / closing link member 86 when the center of gravity of the door unit D is vertically above the rotation support shaft 81. It is because it is configured so that is minimized.

(Door unit rotation moment)
Next, the rotational moment of the door unit D will be described. FIG. 11 is a diagram for explaining the moment due to the dead weight of the door unit D and the moment due to the door unit pressure spring 85. As shown in FIG. 11, the parameters around the door unit D and the door unit pressure spring 85 are set as follows.
・ Moment by the dead weight of the door unit: MD (CW direction is positive)
-Moment by door unit pressurizing part (door unit pressurizing spring 85): MS (CW direction is positive)
・ Door unit rotation angle: θ (closed position is 0 °, CW direction is positive)
-Door unit mass: mD
・ Gravity acceleration: g
The distance between the rotation center 105 (rotation support shaft 81) and the center of gravity G of the door unit: RD
The angle formed by the straight line connecting the door unit center of gravity G and the rotation center 105 (rotation support shaft 81) when the door unit is closed with the vertical direction: θD
The horizontal movement amount of the door opening / closing link member 86 when the door unit rotates by θ: Xθ
The distance between the center of the engaging portion 87 formed integrally with the door base frame 82 and the rotation center 105 (rotation support shaft 81): r
The angle formed by the vertical direction between the center of the engaging portion 87 when the door unit is closed and the straight line connecting the rotation center 105 (rotation support shaft 81): α
A vertical distance between the center of the engaging portion 87 and the rotation center 105 (rotation support shaft 81): Q
-Spring constant of door unit pressure spring 85: k
The length of the door unit pressure spring 85 when the door unit rotates by θ: Lθ
-Natural length of door unit pressure spring 85: L0
・ Horizontal component of door unit pressure spring 85: P (Positive right)
Between the spring hooking portion 101 of the main body frame 80a and the spring opening portion of the door opening / closing link member 86 when the horizontal position of the spring hooking portion of the door opening / closing link member 86 is directly below the spring hooking portion 101 of the main body frame 80a Length: LV
The spring when the horizontal position of the door opening / closing link member 86 side spring hooking portion and the door opening / closing link member 86 side spring hooking portion when the door unit is closed is directly below the spring hooking portion 101 of the main body frame 80a. Distance to the hook: X0
Then, MD and MS have the following relationship.
MD = −mD · g × sin (θD−θ)
MS = P × Q
Further, the horizontal direction component P of the door unit pressurizing spring 85 and the vertical distance Q between the center of the engaging portion 87 and the rotation center 105 (rotation support shaft 81) are as follows.
P = k (Lθ−L0) × (X0−Xθ) / Lθ
Q = r · cos (α−θ)
Also,
Xθ = r (sin α−sin (α−θ))
Lθ = | {(X0−Xθ) ² + LV ² } ^1/2 |
It is.

  FIG. 12 shows the relationship between MD and MS in rotation of the door unit D and the rotation angle θ when design values such as mD, r... are selected as suitable values for this embodiment. In FIG. 12, the sum of moments acting around the door unit D (MD + MS) acts in the CW direction in the range indicated by A (MD + MS> 0), and acts in the CCW direction in the range indicated by B (MD + MS <0).

  As described above, in this embodiment, the door unit pressurizing spring 85 serves as the first urging means so that the center of gravity of the door unit D is the vertical true of the rotation axis from the first door movable range, that is, the door closed state. In the upper section, the following rotational moment is given. That is, a rotational moment that is opposite to the rotational moment due to the dead weight of the door unit D and greater than the rotational moment due to the dead weight of the door unit D is given. Further, as the second urging means, the following rotation is performed in the second door movable range, that is, in the section until the center of gravity of the door unit D is fully opened from the position directly above the rotation axis. Giving moment. That is, a rotational moment greater than the rotational moment due to the dead weight of the door unit D is given in the opposite direction to the rotational moment due to the dead weight of the door unit D and in the open position of the door unit D.

  With such a configuration, it becomes possible for one spring to have both an opening operation assist when the door unit D is opened and a damper function when the door unit D is opened. As a result, it is possible to provide an image forming apparatus that has a simple configuration and has good operability at the beginning of opening the door while suppressing noise and impact at the end of opening the door.

  Here, the first door movable range is more preferably a section where the center of gravity of the door unit D rotates a slightly larger angle than the position directly above the rotation axis from the closed state of the door. In this case, the second movable range of the door is after the time when the center of gravity of the door unit D rotates a slightly larger angle than the position directly above the rotation axis until the door unit D is fully opened. It becomes the section. In the second door movable range, it is more preferable to divide into two sections and change the magnitude of the rotational moment applied by the urging means. That is, in the first half of the second door movable range (the first half of the rotation section after the time when the center of gravity of the door unit D rotates a slightly larger angle than the position directly above the rotation axis), It is better to give a moment slightly smaller than the rotational moment due to its own weight. Further, in the second half of the second door movable range, that is, in the movable range in the vicinity of the door unit D opening, it is preferable to give a rotational moment larger than the rotational moment due to the dead weight of the door unit D. This is because the rotational position at which the rotational moment due to the dead weight of the door unit D becomes zero, that is, the position where the center of gravity of the door unit D is directly above the rotational axis, and the spring pressure of the door unit pressure spring 85 is minimized. This can be done by adjusting (making it near) the point.

  In this way, by using the toggle spring as the urging means, the urging means for applying the rotational moment to the door unit D in the entire range of the movable range of the door is a single spring member (in this embodiment, the door unit pressure spring 85). Can be realized.

  In this embodiment, an electrophotographic image forming apparatus has been described as an image forming apparatus that forms an image on a recording material. However, the present invention is not limited to this. That is, the present invention can be suitably applied to an image forming apparatus using an image forming process such as an electrostatic recording process or a magnetic recording process.

DESCRIPTION OF SYMBOLS 1 Apparatus main body 83 Engagement part 85 Door unit pressurization spring 86 Door opening / closing link member 88 Lock engagement member 89 Door button 90 Spring 91 Frame D Door unit G Center of gravity

Claims (4)

An opening / closing member provided rotatably and opened / closed with respect to the apparatus main body;
A locking mechanism for locking the opening / closing member to the apparatus main body in the closed position;
Have
When the opening / closing member rotates in the opening direction from the closed position, the opening / closing member opens to a position rotated beyond a first position where the position of the center of gravity of the opening / closing member is vertically above the rotation axis of the opening / closing member. In the image forming apparatus in which the rotation direction is switched by the weight of the opening / closing member with the first position as a boundary,
A moving member provided so as to be interlocked with an opening / closing operation of the opening / closing member; a second position located when the opening / closing member takes the closed position; and a position when the opening / closing member takes the open position. A moving member movably provided between the third position and
One spring member having one end attached to the apparatus main body and the other end attached to the moving member,
When the position of the center of gravity of the opening / closing member is closer to the closed position than the first position, the moving member is attached in the direction of the third position so that a rotational moment in the opening direction acts on the opening / closing member. Vigorously,
When the position of the center of gravity of the opening / closing member is closer to the opening position than the first position, the moving member is attached in the direction of the second position so that a rotation moment in the closing direction acts on the opening / closing member. An energizing spring member;
Have
When the opening / closing member is located at the closed position, the spring member biases the moving member in the direction of the third position, rather than a rotational moment acting on the opening / closing member due to the weight of the opening / closing member. Therefore, the rotational moment in the opening direction acting on the opening / closing member is larger,
When the opening / closing member is located at the open position, the spring member biases the moving member toward the second position rather than the rotational moment in the opening direction that acts on the opening / closing member due to the weight of the opening / closing member. Thus, the magnitude of the biasing force of the spring member is set so that the rotational moment acting on the opening / closing member in the closing direction becomes larger.   The said spring member is provided so that the urging | biasing force of the said spring member may become the minimum when the position of the gravity center of the said opening / closing member is located in the said 1st position. Image forming apparatus. The moving member is
When the position of the center of gravity of the opening / closing member is located at the first position, the attachment portion of the apparatus main body to which one end of the spring member is attached and the attachment portion of the moving member to which the other end of the spring member is attached Is located at the fourth position where the distance between
3. The image forming apparatus according to claim 1, wherein a distance from the rotation axis is set to increase in the order of the third position, the fourth position, and the second position. The moving member is provided to be movable in one direction with respect to the apparatus main body,
A first elongated hole-shaped portion that is movably engaged in an engagement portion provided in an apparatus main body so as to be movable in the one direction;
A direction intersecting the one direction as a longitudinal direction, and a second elongated hole-shaped portion with which an engagement portion provided on the opening / closing member is movably engaged;
The image forming apparatus according to claim 3, further comprising:

Images