JP2010060777A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent electrostatic charge by always grounding a guide member by using existing configuration. <P>SOLUTION: After transferring a toner image formed on an image carrier to a recording medium in an apparatus body, the toner image is fixed on the recording medium by a fixing means. The image forming apparatus includes: the guide member 23 which is provided turnably in the apparatus body 1, and forms a conveyance path to guide the recording medium on which the toner image has been fixed by the fixing means; and an biasing member which separates the guide member 23 from the conveyance path and biases it to turn to at least a jamming disposal position. The guide member 23 includes a conduction part, and the apparatus body 1 includes a grounded conduction part. The biasing member is arranged so as to always come into contact with the respective conduction parts regardless of the turning position of the guide member 23. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus characterized by a grounding structure for preventing charging of a guide member that guides a path of a recording medium.

  2. Description of the Related Art Conventionally, as an image forming apparatus, in order to prevent a member constituting a conveyance path for conveying a recording medium such as paper from being charged, for example, a configuration described in Patent Documents 1 to 3 is known.

  That is, in Patent Document 1, when the post-paper guiding member is positioned on the side frame, it is locked by the spring force of the torsion coil spring, and the drive roller shaft and the reinforcing frame are grounded from the torsion coil spring through the side frame. The configuration is disclosed.

  Further, in Patent Document 2, one end of a conductive elastic member is attached so as to be in pressure contact with the conductive member of the functional unit, and the other end of the elastic member is provided in the device when the functional unit is inserted into the device. A configuration in which the conductive member is pressed against the conductive member is disclosed.

  Further, in Patent Document 3, when a cartridge is mounted on the mounting portion, first, the door is closed, the cartridge is pushed by the pushing portion, and then pulled by a spring, and this spring is brought into contact with the electric board. A configuration in which the ground is made to be grounded is disclosed.

JP 2005-41610 A JP 2006-95963 A Japanese Patent Laid-Open No. 10-254328

  However, in any of the configurations of Patent Documents 1 to 3, the springs are elastically deformed and grounded by mounting the component parts (paper guiding rear member, functional unit, cartridge) on the apparatus main body. It has become. In other words, the grounding state is not always obtained, but only after installation.

  Further, in any of the configurations of Patent Documents 1 to 3, it is necessary to redesign some components other than the spring as a dedicated configuration. Therefore, it cannot be adopted in the existing configuration.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of preventing charging by always grounding a guide member using an existing configuration.

As a means for solving the above problems, the present invention provides:
An image forming apparatus in which a toner image transferred to a recording medium is fixed by fixing means provided in the apparatus main body,
A guide member which is rotatably provided in the apparatus main body and guides a recording medium on which a toner image is fixed by the fixing unit by forming a conveyance path;
An urging member that urges the guide member to move away from the conveyance path and rotate at least to the jam processing position;
The guide member includes a first conductive portion,
The apparatus main body includes a second conductive portion that is grounded,
The urging member is arranged so as to always come into contact with each conductive portion regardless of the rotation position of the guide member.

  With the above configuration, if a jam (paper jam) occurs in the conveyance path of the fixing unit, the guide member can be reliably rotated to the jam processing position by the urging member. Therefore, it is possible to eliminate the jam with high work efficiency. In addition, the guide member is always grounded by the biasing member regardless of the rotation position thereof, so that it is not charged by the conductive portion. As a result, it is possible to prevent electrical components provided in the fixing unit from being damaged and noise from being generated in the toner image to be fixed on the recording medium.

  It is preferable that positioning means for positioning the guide member at a mounting position that constitutes a part of the transport path is provided.

  The positioning means may be formed of a pressing portion that is formed on a door provided in the apparatus main body so as to be openable and closable, and presses the guide member to position the mounting member when the door is positioned at the closed position.

The biasing member is
A winding portion that is externally mounted on a support shaft that is the rotation center of the guide member;
A first urging portion that extends from one end of the winding portion, is formed in a substantially U shape, and is in pressure contact with the first conductive portion;
A second urging portion extending from the other end of the winding portion and in pressure contact with the second conductive portion;
Is preferably provided.

  With the above configuration, if the winding portion of the urging member is externally mounted on the support shaft, the first urging portion can be brought into pressure contact with the first conductive portion, and the second urging portion can be brought into pressure contact with the second conductive portion. Easy assembly workability with simple configuration.

The guide member has a configuration in which a reinforcing plate is attached to a guide plate and covered with a covering plate,
The first conductive portion is a reinforcing plate attached to the guide plate, and the first biasing portion is inserted into and brought into contact with a locking recess formed by the guide plate and the reinforcing plate,
The second conductive portion is a support frame provided in the fixing unit, and is preferably in contact with a latch receiving portion formed between the second conductive portion and the cover.

  With the above configuration, the guide member can be grounded via the biasing member while using the existing locking recess and locking receiving portion. In addition, regardless of the rotation position of the guide member, the urging member can be conducted to the conductive portion to maintain the grounded state.

  According to the present invention, even when a jam occurs in the conveyance path of the fixing unit, the guide member can be reliably rotated to the jam processing position by the urging member and can be easily eliminated. In addition, a conductive portion that is grounded is formed on the guide member, and it is only necessary to contact a biasing member provided to bias the guide member so as to separate the guide member from the conveyance path. No design change is required, and it can be manufactured at low cost. Further, even if the guide member is rotated to any position, the urging member can maintain the grounded state, and the electric component provided in the fixing unit can be damaged, or the toner image to be fixed on the recording medium. It is possible to prevent noise from occurring.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram of an image forming apparatus according to the present embodiment. In this image forming apparatus, a sheet feeding unit 2, an image forming device 3, a fixing device 4 (fixing means), and the like are provided in an apparatus main body 1.

  On the side surface of the apparatus main body 1, a door 100 is provided for opening and closing an area in which the image forming device 3, the fixing device 4, and the like are accommodated. A pressing portion 101 (see FIG. 9 and the like) is formed above the inner surface of the door 100 to press the guide member 23 of the fixing device 4 and position it at the mounting position constituting the conveyance path as will be described later. Yes.

  The paper feed unit 2 is composed of a plurality of cassettes 6 in which different sizes of paper 5 (recording media) are accommodated. A sheet 5 of a size selected on an operation panel (not shown) or automatically selected is discharged from the corresponding cassette 6 and conveyed by a conveyance roller (not shown).

  The image forming apparatus 3 includes an intermediate transfer belt 7 and four image forming units 8 arranged along the intermediate transfer belt 7. The intermediate transfer belt 7 is stretched between a pair of support rollers 9, and rotates in the direction of the arrow in FIG. 1 by driving a motor (not shown) to rotate one of the support rollers 9. Yes. Each image forming unit 8 charges the photosensitive member 11 (image carrier) with the charger 10, selectively exposes with the exposure device 12 to form an electrostatic latent image, and attaches the toner with the developing device 13, A toner image is formed.

  The toner image formed by each image forming unit 8 is transferred to the intermediate transfer belt 7 by pressing the intermediate transfer belt 7 against the photoconductor 11 by the primary transfer roller 14. Further, the toner image transferred to the intermediate transfer belt 7 by the support roller 9 and the secondary transfer roller 15 is transferred to the paper 5. Each image forming unit 8 is supplied with toner of each color of yellow (Y), magenta (M), cyan (C), and black (Bk) from the toner cartridge.

  As shown in FIGS. 1 to 11, the fixing device 4 is a device in which a pressure roller 16 and a fixing roller 17 are rotatably supported by support frames 18 provided at both ends. As shown in FIG. 8, the support frame 18 is connected by a mounting plate 20, and the upper surface side is covered with a cover 19. A guide piece 19 a extending upward is formed on a part of the cover 19. The guide piece 19a constitutes a locking receiving portion 18a with which the second urging portion 34 of the torsion coil spring 28 described later is locked with the support frame 18. As shown in FIG. 11, a belt 22 is stretched between the fixing roller 17 and the heating roller 21. By rotating the pressure roller 16 with a motor (not shown), the fixing roller 17 and the heating roller 21 are rotated via the belt 22.

  Further, as shown in FIGS. 1 to 3, a conveyance path is formed in the fixing device 4 by the guide member 23 so that the toner image is fixed on the passing paper 5 and then guided to the discharge tray 24. It has become.

  As shown in FIG. 5, the guide member 23 has a reinforcing plate 26 (conductive portion) fixed to the guide plate 25 and is covered with a covering plate 27 as shown in FIG. Is supported so as to be rotatable around the center. A torsion coil spring 28 (biasing member) is attached to the support shaft 1a, and the guide member 23 is biased away from the transport path. The guide member 23 is positioned by locking means (not shown) and constitutes a part of the transport path.

  The guide plate 25 is formed by molding a synthetic resin material, and forms a transport path with the apparatus body 4a side of the fixing device 4 as shown in FIG. The guide plate 25 is rotatably provided with a guide roller 26a that guides the sheet 5 so as to be conveyed by a guide roller 19b that is rotatably provided on the apparatus main body 4a side. A pair of levers 29 are attached to the guide plate 25. These levers 29 are configured to detect the presence or absence of the sheet 5 passing through the transport path (between the guide rollers).

  As shown in FIG. 5, the reinforcing plate 26 has a problem (e.g., the paper 5 cannot be properly conveyed) due to deformation such as warpage only with the resin guide plate 25, so that the guide can be used to prevent this deformation. Provided integrally with the plate 25. A conductive metal material is used for the reinforcing plate 26. In the guide plate 25, a photoswitch (not shown) for detecting whether or not the lever 29 is operated is attached as an electrical component. A detection signal from the photoswitch is output to a control device (not shown) so that the passing state of the paper 5 is detected.

  In the state in which the reinforcing plate 26 is integrated with the guide plate 25, as shown in FIG. 6, the standing wall 25a formed on a part of the guide plate 25 and a part of the reinforcing plate 26 are bent in a crank shape. A cylindrical guide recess 30 is formed by the guide wall 26b. The reason why the guide wall is bent in a crank shape is to obtain a desired strength with a simple structure without making it thick. And in order to obtain this reinforcement structure, the space which can be utilized as the guide recessed part 30 conventionally is formed. That is, the torsion coil spring 28 to be described later can be attached without making any changes to the existing configuration.

  As shown in FIG. 4, the covering plate 27 is fixed to a guide plate 25 in which a reinforcing plate 26 is integrated, and the entire portion excluding the surface of the guide plate 25 that constitutes the conveyance path, including a photo switch and the like. cover. A gap is originally formed between the guide piece 19a of the cover 19 and the support frame 18, as shown in FIG. The gap is used as the attachment portion 31 as an engagement receiving portion 18a for engaging a second urging portion 34 of the torsion coil spring 28 described later. Further, as shown in FIGS. 9 and 10, a press receiving portion 102 that is pressed by a pressing portion 101 formed on the door 100 of the apparatus main body 1 is formed at one end portion of the cover plate 28. The pressure receiving portion 102 can be pressed by the pressing portion 101 in a state where the guide member 23 is located at an open position separated from the conveyance path. Then, as shown in FIG. 11, with the door 101 completely closed with respect to the apparatus main body 1, the pressing portion 101 presses the pressing receiving portion 102 against the urging force of the torsion coil spring 28. The member 23 is positioned at a guide position that constitutes a part of the transport path, and is positioned by locking means (not shown).

  As shown in FIGS. 6 and 7, the torsion coil spring 28 includes a coil portion 32 that is externally mounted on the support shaft 1 a of the cover plate 27, and a first urging portion 33 and a second attachment portion that are respectively formed at both ends thereof. It consists of a force unit 34. The first urging portion 33 has a so-called hairpin shape that is bent in a substantially U shape and is formed so as to gradually spread from the bent portion. The first urging portion 33 has a narrow insertion tip side and can be easily inserted into the guide recess 30. Moreover, when inserted to a predetermined position, the expanded portion is elastically deformed inward, so that a grounded state can be reliably obtained. Further, the first urging portion 33, the second urging portion 34, and the coil portion 32 are formed by attaching the first urging portion 33 to the guide recess 30 in a state where the coil portion 32 is attached to the support shaft of the cover plate 27. In addition, the second urging portion 34 is inserted into the mounting portion 31 so as to be in contact with each other. Therefore, it is possible to simply attach the coil portion 32 to the support shaft, and the assembly workability is not deteriorated. In the attached state, the guide member 23 is biased by the torsion coil spring 28 so as to be separated from the conveyance path side. In this case, the urging force by the torsion coil spring 28 is set to be slightly larger than the weight of the guide member 23. Therefore, if the locked state by the locking means is released, the guide member 23 can be automatically rotated or easily rotated, and the conveyance path can be easily opened.

  Next, the operation of the image forming apparatus having the above configuration will be described.

  At the time of image formation, color print data obtained by reading an image with the image reading unit or image data output from a personal computer or the like is subjected to predetermined signal processing by the control unit, and then yellow (Y), magenta (M), cyan (C), and black (Bk) are supplied to each image forming unit 8 as image signals of respective colors. Each image forming unit 8 projects a laser beam modulated by an image signal onto each photosensitive drum 7 to form an image latent image. A yellow, magenta, cyan, and black toner image is formed on each photosensitive drum 7. The formed yellow, magenta, cyan, and black toner images are sequentially primary-superimposed on the moving intermediate transfer belt 7 by the action of the primary transfer roller 14. The superimposed toner image formed on the intermediate transfer belt 7 in this way moves to the secondary transfer roller 15 side as the intermediate transfer belt 7 moves.

  Further, the paper 5 is supplied from the paper supply unit 2. The supplied paper 5 is conveyed between the secondary transfer roller 15 and the intermediate transfer belt 7 by a conveyance roller (not shown), and the toner image formed on the intermediate transfer belt 7 is transferred. The sheet 5 to which the toner image has been transferred is further conveyed to the fixing device 4 where the transferred toner image is fixed. When the paper 5 passes through the fixing device 4, the paper 5 may be charged by friction or the like, and the reinforcing plate 26 made of a metal material may be charged. However, as described above, the torsion coil spring 28 is in contact with the reinforcing plate 26, and the torsion coil spring 28 is in contact with the grounded support frame 18. Therefore, the reinforcing plate 26 is discharged through the torsion coil spring 28 and the support frame 18, and the reinforcing plate 26 is not charged. As a result, the electrical components provided on the guide member 23 are damaged due to the adverse effects of charging, or noise is generated when the toner image is fixed on the paper 5 and proper image formation cannot be performed. Occurrence can be prevented.

  Further, when a paper jam or the like occurs in the fixing device 4, the conveying state is released by releasing the locking state by a locking unit (not shown) and rotating the guide member 23 about the support shaft 1 a. . During this time, the conductive state between the reinforcing plate 26 and the support frame 18 is maintained by the torsion coil spring 28, and the grounded state is not released. That is, not only during image formation but also when the guide member 23 is opened, the grounding state is always maintained, charging can be prevented, and the occurrence of the above-described problems can be reliably prevented.

  In addition, this invention is not limited to the structure described in the said embodiment, A various change is possible. For example, the guide member 23 is provided integrally with the fixing device 4, but may be provided separately. Moreover, although the torsion coil spring 28 is provided only at one end side of the support shaft 1a, it may be provided at both ends, or may be provided at an intermediate portion if possible.

1 is a schematic view of an image forming apparatus according to an embodiment. FIG. 2 is a perspective view of the fixing device in FIG. 1. It is a perspective view which shows the state which rotated the guide member from FIG. 2, and opened the conveyance path | route. It is a perspective view of the guide member of FIG. FIG. 5 is a perspective view of a guide plate and a reinforcing plate showing a state where a covering plate is removed from FIG. 4. It is a perspective view which shows the attachment part of the torsion coil spring of FIG. FIG. 3 is a front view showing a main body side of a fixing device to which the guide plate of FIG. 2 is mounted, a torsion coil spring, and a locking portion thereof. FIG. 3 is a partial perspective view of a main body side of a fixing device to which the guide plate of FIG. 2 is attached. It is a perspective view which shows the fixing device and door of FIG. It is front sectional drawing which shows the fixing device of FIG. 1, and the door of an open position. It is front sectional drawing which shows the fixing device of FIG. 1, and the door of a closed position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Main body 1a ... Spindle 2 ... Paper feed unit 3 ... Image forming device 4 ... Fixing device 5 ... Paper 6 ... Cassette 7 ... Intermediate transfer belt 8 ... Image forming unit 9 ... Support roller 10 ... Charger 11 ... Photoconductor DESCRIPTION OF SYMBOLS 12 ... Exposing device 13 ... Developing device 14 ... Primary transfer roller 15 ... Secondary transfer roller 16 ... Pressure roller 17 ... Fixing roller 18 ... Support frame 18a ... Locking receiving part 19 ... Cover 19a ... Guide piece 19b ... Guide roller DESCRIPTION OF SYMBOLS 20 ... Fixing frame 21 ... Heating roller 22 ... Belt 23 ... Guide member 24 ... Discharge tray 25 ... Guide plate 25a ... Standing wall 26 ... Reinforcement plate 26a ... Guide roller 26b ... Guide wall 27 ... Cover plate 28 ... Torsion coil spring 29 ... Lever DESCRIPTION OF SYMBOLS 30 ... Guide recessed part 31 ... Attachment part 32 ... Coil part 33 ... 1st urging | biasing part 34 ... 2nd urging | biasing part

Claims (5)

An image forming apparatus in which a toner image transferred to a recording medium is fixed by fixing means provided in the apparatus main body,
A guide member which is rotatably provided in the apparatus main body and guides a recording medium on which a toner image is fixed by the fixing unit by forming a conveyance path;
An urging member that urges the guide member to move away from the conveyance path and rotate at least to the jam processing position;
The guide member includes a first conductive portion,
The apparatus main body includes a second conductive portion that is grounded,
The image forming apparatus according to claim 1, wherein the urging member is arranged so as to always come into contact with each of the conductive portions regardless of a rotation position of the guide member.   The image forming apparatus according to claim 1, further comprising a positioning unit that positions the guide member at a mounting position that constitutes a part of the transport path.   The positioning means is formed on a door provided to be openable and closable on the apparatus main body, and is configured by a pressing portion that presses the guide member and positions the mounting member by positioning the door at a closed position. The image forming apparatus according to claim 2. The biasing member is
A winding portion that is externally mounted on a support shaft that is the rotation center of the guide member;
A first urging portion that extends from one end of the winding portion, is formed in a substantially U shape, and is in pressure contact with the first conductive portion;
A second urging portion extending from the other end of the winding portion and in pressure contact with the second conductive portion;
The image forming apparatus according to claim 1, further comprising: The guide member has a configuration in which a reinforcing plate is attached to a guide plate and covered with a covering plate,
The first conductive portion is a reinforcing plate attached to the guide plate, and the first biasing portion is inserted into and brought into contact with a locking recess formed by the guide plate and the reinforcing plate,
The image forming apparatus according to claim 4, wherein the second conductive portion is a support frame provided in the fixing unit, and is in contact with a latch receiving portion formed between the second conductive portion and the cover.