JP2009192704A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stop charging by having a guide member always grounded by using an existing composition. <P>SOLUTION: After transferring a toner image which is formed on an image carrier 12 to a recording medium 5 in an apparatus body 1, the toner image is fixed to the recording medium 5 by a fixing means 4. The image forming apparatus includes the guide member 24 which is turnably arranged in the apparatus body 1 for guiding the recording medium 5 which is transported from the fixing means 4 by forming a transporting path and a biasing member 29 for biasing the guide member 24 to be separated from the transporting path. A conducting section 27 which is grounded is formed in the guide member 24. The biasing member 29 is arranged to be always in contact with the conducting section 27 regardless of the turning position of the guide member 24. <P>COPYRIGHT: (C)2009,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 formed on an image carrier is transferred to a recording medium within the apparatus body, and then the toner image is fixed on the recording medium by a fixing unit,
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;
A biasing member that biases the guide member so as to be separated from the transport path;
The guide member includes a conductive portion,
The apparatus main body includes a 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 this configuration, even if the guide member is rotated to any position between the position where the guide path is formed and the position where the guide member is separated, the urging member always contacts each conductive portion and can maintain the grounded state. . Further, since the guide member can be grounded with a simple configuration in which only the urging member is attached, it is excellent in assemblability and can be manufactured at low cost.

The guide member is provided in the fixing means so as to be rotatable about a support shaft,
The biasing member is in pressure contact with the guide member, a coil portion that is externally mounted on the support shaft, a first biasing portion that is in pressure contact with the conductive portion of the guide member, and the guide member is separated from the conveyance path. It is preferable that the torsion coil spring includes a second urging portion on the other end side that is urged so as to be in pressure contact with the conduction portion of the apparatus main body.

The torsion coil spring is formed such that the first urging portion is bent in a substantially U shape and gradually spreads from the bent portion,
Preferably, the guide member includes a guide recess in which the first urging portion is press-fitted and the conductive portion is exposed to at least one of the press-fitted portions.

  With this configuration, it is possible to achieve electrical connection with the conductive portion simply by press-fitting the first urging portion into the guide recess.

  The guide recess is preferably formed of a part of the guide member and a part of the reinforcing member fixed to the guide member and made of a conductive material.

  The urging force by the urging member is preferably slightly larger than the weight of the guide member.

  According to the present invention, 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 be separated from the conveyance path. The parts can be manufactured at low cost without requiring significant design changes. Moreover, even if the guide member is rotated to any position, the grounding state can be maintained by the urging member.

  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.

  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 having a size selected on an operation panel (not shown) or automatically selected is discharged from the corresponding cassette 6.

  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 driving roller 9 and a driven roller 10, and rotates in the direction indicated by an arrow in FIG. 1 by driving a motor (not shown) to rotate the driving roller 9. ing. Each image forming unit 8 charges the photoconductor 12 (image carrier) with the charger 11, selectively exposes it with the exposure device 13 to form an electrostatic latent image, attaches toner with the developer 14, 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 photoreceptor 12 by the primary transfer roller 15. Further, the toner image transferred to the intermediate transfer belt 7 by the driving roller 9 and the secondary transfer roller 16 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, 2, 7, and 9, the fixing device 4 includes a pressure roller 17 and a fixing roller 18 that are rotatably supported by a support frame 19. The pressure roller 17 is covered with a cover 20 except for the fixing roller 18 side. As shown in FIG. 9, a fixing frame 21 (conducting portion) is disposed inside the top cover 20a and the side cover 20b. The fixing frame 21 is a metal plate having a substantially L-shaped cross section, is grounded, and has an upper surface exposed at a part of the upper surface cover 20a. A belt 23 is stretched between the fixing roller 18 and the heating roller 22. By rotating the pressure roller 17 with a motor (not shown), the fixing roller 18 and the heating roller 22 are rotated via the belt 23.

  In the fixing device 4, a conveyance path is formed by the guide member 24, and after the toner image is fixed on the passing paper 5, the toner image is guided to the discharge tray 25.

  As shown in FIGS. 5 and 6, the guide member 24 has a reinforcing plate 27 (conducting portion) fixed to the guide plate 26 and covered with a cover plate 28 as shown in FIG. It is supported so as to be rotatable about the support shaft 1a. A torsion coil spring 29 (biasing member) is attached to the support shaft 1a, and the guide member 24 is biased so as to be separated from the conveyance path. The guide member 24 is positioned by locking means (not shown) and constitutes a part of the transport path.

  The guide plate 26 is formed by molding a synthetic resin material, and forms a conveyance path with the support frame 19 side of the fixing device 4. The guide plate 26 is rotatably provided with a guide roller 26 a that guides the paper 5 so as to be conveyed by a guide roller 19 a that is rotatably provided on the support frame 19 side. A lever 30 is attached to the guide plate 26. The lever 30 detects the presence or absence of the sheet 5 passing through the transport path (between the guide rollers).

  The reinforcing plate 27 is provided integrally with the guide plate 26 so as to prevent the deformation (e.g., the sheet 5 cannot be properly conveyed) due to deformation such as warpage only with the resin guide plate 26. It is done. A conductive metal material is used for the reinforcing plate 27. In the guide plate 26, a photo switch (not shown) for detecting whether or not the lever 30 provided on the guide plate 26 is operated is mounted 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 27 is integrated with the guide plate 26, the upright wall 26b formed on a part of the guide plate 26 and the guide wall 27a formed by bending a part of the reinforcing plate 27 in a crank shape are cylindrical. The guide recess 31 is formed. 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 31 conventionally is formed. In other words, the torsion coil spring 29 described later can be attached without making any changes to the existing configuration.

  The cover plate 28 is fixed to the guide plate 26 in which the reinforcing plate 27 is integrated, and covers the entire portion excluding the surface of the guide plate 26 that constitutes the transport path, including a photo switch and the like. Support shafts are provided at both ends of the cover plate 28, and the guide member 24 is supported by the support frame 19 so as to be rotatable about the support shaft. Further, as shown in FIGS. 8 and 9, a gap is originally formed between the cover plate 28 and the apparatus main body 1. The gap is used as a mounting portion 32 for mounting a torsion coil spring 29 described later.

  The torsion coil spring 29 includes a coil portion 33 that is externally mounted on the support shaft of the cover plate 28, and a first urging portion 34 and a second urging portion 35 that are formed at both ends thereof. The first urging portion 34 has a so-called hairpin shape that is bent into a substantially U shape and is formed so as to gradually spread from the bent portion. The first urging portion 34 has a narrow insertion tip side, and can be easily inserted into the guide recess 31. 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 34, the second urging portion 35, and the coil portion 33 are formed by attaching the first urging portion 34 to the guide recess 31 in a state where the coil portion 33 is attached to the support shaft of the cover plate 28. In addition, the second urging portion 35 can be press-fitted into the mounting portion 32. Therefore, it is possible to simply attach the coil portion 33 to the support shaft, and the assembly workability is not deteriorated. In the attached state, the guide member 24 is urged so as to be separated from the conveyance path side by the torsion coil spring 29. In this case, the urging force by the torsion coil spring 29 is set to be slightly larger than the weight of the guide member 24. Therefore, if the latching state by the latching means is released, the guide member 24 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 primarily transferred onto the moving intermediate transfer belt 7 by being sequentially superimposed by the action of the primary transfer roller 15. The superimposed toner image formed on the intermediate transfer belt 7 in this way moves to the secondary transfer roller 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 16 and the intermediate transfer belt 7 by the conveyance roller, 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 due to friction or the like, and the reinforcing plate 27 made of a metal material may be charged. However, as described above, the torsion coil spring 29 is in contact with the reinforcing plate 27, and the torsion coil spring 29 is in contact with the grounded support frame 19. Therefore, the reinforcing plate 27 is discharged via the torsion coil spring 29 and the support frame 19, and the reinforcing plate 27 is not charged. As a result, the electrical components provided on the guide member 24 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 locking state by a locking means (not shown) is released, and the guide member 24 is rotated around the support shaft 1a as shown in FIG. This opens the transport path. During this time, the conductive state between the reinforcing plate 27 and the support frame 19 is maintained by the torsion coil spring 29, and the grounded state is not released. That is, not only during image formation but also when the guide member 24 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 24 is provided integrally with the fixing device 4, but may be provided separately. Further, although the torsion coil spring 29 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. It is a perspective view in the state which removed the coating board from FIG. FIG. 6 is a partially enlarged perspective view of FIG. 5. FIG. 4 is a partially enlarged plan view of FIG. 3. It is a figure which shows the state which removed the guide member in FIG. FIG. 2 is a schematic cross-sectional view of the vicinity including the fixing device of FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Apparatus main body 1a ... Spindle 2 ... Paper feed unit 3 ... Image forming apparatus 4 ... Fixing device (fixing means)
5 ... paper (recording medium)
6 ... cassette 7 ... intermediate transfer belt 8 ... image forming unit 9 ... driving roller 10 ... driven roller 11 ... charger 12 ... photoconductor (image carrier)
DESCRIPTION OF SYMBOLS 13 ... Exposing device 14 ... Developing device 15 ... Primary transfer roller 16 ... Secondary transfer roller 17 ... Pressure roller 18 ... Fixing roller 19 ... Support frame 19a ... Guide roller 20 ... Cover 20a ... Top cover 20b ... Side cover 21 ... Fixing frame 22 ... heating roller 23 ... belt 24 ... guide member 25 ... discharge tray 26 ... guide plate 26a ... guide roller 26b ... stand wall 27 ... reinforcing plate (conductive portion)
27a ... guide wall 28 ... cover plate 29 ... torsion coil spring (biasing member)
DESCRIPTION OF SYMBOLS 30 ... Lever 31 ... Guide recessed part 32 ... Mounting part 33 ... Coil part 34 ... 1st biasing part 35 ... 2nd biasing part

Claims (5)

An image forming apparatus in which a toner image formed on an image carrier is transferred to a recording medium within the apparatus body, and then the toner image is fixed on the recording medium by a fixing unit,
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;
A biasing member that biases the guide member so as to be separated from the transport path;
The guide member includes a conductive portion,
The apparatus main body includes a 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 guide member is provided in the fixing means so as to be rotatable about a support shaft,
The biasing member is in pressure contact with the guide member, a coil portion that is externally mounted on the support shaft, a first biasing portion that is in pressure contact with the conductive portion of the guide member, and the guide member is separated from the conveyance path. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus includes a torsion coil spring including a second urging portion on the other end side that is urged to be pressed and is in pressure contact with a conduction portion of the apparatus main body. The torsion coil spring is formed such that the first urging portion is bent in a substantially U shape and gradually spreads from the bent portion,
The image forming apparatus according to claim 2, wherein the guide member includes a guide concave portion into which the first urging portion is press-fitted and the conductive portion is exposed to at least one of the press-fitted portions.   The image forming apparatus according to claim 3, wherein the guide concave portion is formed by a part of the guide member and a part of a reinforcing member fixed to the guide member and made of a conductive material.   The image forming apparatus according to claim 1, wherein a biasing force by the biasing member is slightly larger than a weight of the guide member.

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