JP2013015556A - Grounding structure, and electronic equipment including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grounding structure that reliably connects movable units or members to the ground with a simple configuration, and electronic equipment including the ground structure.SOLUTION: A leaf spring member 43 is a grounding member that establishes an electrical conduction between a first frame 40 on an image forming apparatus 100 body side and a second frame 41 on an image reading unit 20 side, and connects the image reading unit 20 to the ground; the leaf spring member 43 is fixed to the first frame 40 with a first screw 45. A compression coil spring 47 for bringing the leaf spring member 43 into a press-contact with the second frame 41 is fixed to the first frame 40 with a second screw 50.

Description

  The present invention relates to a grounding structure used in an electronic apparatus such as an image forming apparatus.

  Conventional image forming apparatuses are known in which a constituent unit is movable (detachable) with respect to the main body of the image forming apparatus in order to facilitate jam processing and maintenance work. Such a unit is electrically connected to the image forming apparatus main body through a protective earth wire necessary for safety standards, but no other grounding (earthing) measures have been taken.

  However, due to recent digitization of the apparatus, electromagnetic noise is emitted from the image forming apparatus, and the electromagnetic noise may affect other electronic devices around the image forming apparatus. Therefore, the importance of EMI (Electro Magnetic Interference) countermeasures has increased, and there is a demand for a more reliable grounding structure for members such as movable units and exterior covers.

  As a general grounding structure, a method is known in which a leaf spring is used as a grounding member, one end of the leaf spring is screw-fixed to one member, and the other end is pressed against the other member by the urging force of the leaf spring. . However, with this structure, the leaf spring may be deformed due to vibration, impact, or the like, or a displacement between members that need to be grounded may occur, leading to unstable leaf spring contact. Although a method using a coil spring as a grounding member is conceivable, a coil spring formed of a wire rod has high impedance and a small contact area, so that sufficient grounding cannot be performed.

  Therefore, a method for stabilizing the grounding property between the image forming apparatus main body and the unit or member has been proposed. For example, in Patent Document 1, one end of a leaf spring is screwed to one member and the other end of the leaf spring is fixed. A method of adsorbing to the other member by the magnetic force of a magnet or an electromagnet is disclosed.

JP-A-5-307282

  However, in the method of Patent Document 1, when the unit or member is moved, it is necessary to separate the leaf spring attracted by the magnetic force from the other member, and the leaf spring may be deformed depending on the strength of the attracting force. It was. In addition, when the electromagnet is used, the number of constituent members is increased and the wiring becomes complicated, and there is a problem that power consumption for energizing the electromagnet is also increased. In the above description, the problem of the grounding structure in the image forming apparatus has been described. However, the situation is the same in other electronic devices other than the image forming apparatus.

  In view of the above problems, an object of the present invention is to provide a grounding structure capable of reliably grounding a movable unit or member with a simple configuration and an electronic apparatus including the same.

  In order to achieve the above object, the present invention provides a grounding structure for an electronic device that grounds a first member and a second member that are arranged to face each other, and a fixing portion that is fixed to the first member; A leaf spring member having a contact portion that makes surface contact with the second member, and an elastically deformable connecting portion that connects the contact portion and the fixing portion, and is disposed substantially perpendicular to the contact portion. And a grounding structure for an electronic device having one end fixed to the first member and the other end having a compression coil spring that presses the contact portion toward the second member.

  According to the present invention, in the grounding structure configured as described above, the compression coil spring has a coil end surface that presses the contact portion, which is closed-end processed.

  Further, according to the present invention, in the grounding structure configured as described above, the compression coil spring is characterized in that a coil end surface that presses the contact portion is subjected to grinding end processing.

  Moreover, this invention is an electronic device provided with the ground structure of the said structure.

  According to the first configuration of the present invention, since the contact portion of the leaf spring member is pressed against the second member by the compression coil spring, the contact portion and the second member are surely brought into surface contact. Accordingly, the first member and the second member can be reliably grounded, and there is no possibility that the contact between the second member and the leaf spring member becomes unstable. Further, the contact pressure of the leaf spring member can be arbitrarily set by selecting the spring constant of the compression coil spring. Furthermore, the contact pressure of the leaf spring member can be maintained without using an expensive spring steel material as the material of the leaf spring member, which is advantageous in terms of cost. Therefore, the grounding structure is effective as an EMI countermeasure for electronic equipment.

  According to the second configuration of the present invention, in the grounding structure of the first configuration, the coil end surface of the compression coil spring that presses the contact portion is closed-end processed so that the coil end surface of the compression coil spring becomes the contact portion. The contact portion of the leaf spring member is brought into pressure contact with the second member on the surface, and the contact state between the contact portion and the second member can be stabilized.

  According to the third configuration of the present invention, in the grounding structure of the first configuration, the coil end surface of the compression coil spring that presses the contact portion is subjected to grinding end processing so that the coil end surface of the compression coil spring becomes the contact portion. Surface contact is possible, and the contact portion of the leaf spring member is pressed against the second member by the surface, and the contact state between the contact portion and the second member can be further stabilized.

  In addition, according to the fourth configuration of the present invention, the use of the ground structure having any one of the first to third configurations effectively suppresses the influence of electromagnetic noise emission on other electronic devices. The electronic device has an effective EMI countermeasure.

1 is a schematic cross-sectional view showing an internal configuration of an image forming apparatus 100 using a grounding structure of the present invention Side surface sectional view showing the internal structure of the image reading unit 20 Sectional drawing which shows one Embodiment of the earthing | grounding structure of the image reading part 20 and the image forming apparatus 100 main body The perspective view of the leaf | plate spring member 43 used for the earthing | grounding structure of this embodiment. The perspective view of the compression coil spring 47 used for the grounding structure of this embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing an internal configuration of an image forming apparatus having a grounding structure according to the present invention. The image forming apparatus 100 is a tandem type color copying machine, and four image forming portions Pa, Pb, Pc, and Pd are arranged in this order from the left side in FIG. The image forming portions Pa to Pd are provided corresponding to images of four different colors (magenta, cyan, yellow, and black), and magenta, cyan, yellow, and black are respectively performed by charging, exposure, development, and transfer processes. Are sequentially formed.

  These image forming portions Pa to Pd are provided with photosensitive drums 1a, 1b, 1c and 1d which carry visible images (toner images) of the respective colors, and further rotate counterclockwise in FIG. An intermediate transfer belt 8 is provided adjacent to each of the image forming portions Pa to Pd. The toner images formed on the photosensitive drums 1 a to 1 d are sequentially transferred and superimposed on the intermediate transfer belt 8 that moves while contacting the photosensitive drums 1 a to 1 d, and then the secondary transfer roller 9. Is transferred onto a sheet 26 as an example of a recording medium, and further fixed on the sheet 26 in the fixing device 7 and then discharged from the apparatus main body. An image forming process for each of the photosensitive drums 1a to 1d is executed while rotating the photosensitive drums 1a to 1d clockwise in FIG.

  A sheet 26 as a recording medium to which the toner image is transferred is accommodated in a sheet feeding cassette 10 at the lower part of the apparatus. The paper 26 is stacked on a paper stacking plate 28 of the paper feed cassette 10, and the paper 26 is fed by rotating the pickup roller 29 with the upper surface of the paper 26 being pressed against the pickup roller 29 with a predetermined pressure. Is started. Then, only the uppermost one of the plurality of sheets 26 is separated by the paper feed roller pair 30 constituted by the feed roller 30 a and the retard roller 30 b and conveyed toward the sheet conveyance path 11. The sheet 26 that has passed through the sheet conveying path 11 reaches the registration roller pair 14 and is conveyed to a nip between the secondary transfer roller 9 and a driving roller 13 of the intermediate transfer belt 8 described later in accordance with the image formation timing. .

  A sheet made of dielectric resin is used for the intermediate transfer belt 8, and a (seamless) belt mainly having no seam is used. Further, a blade-like belt cleaner 17 for removing toner remaining on the surface of the intermediate transfer belt 8 is disposed on the downstream side in the moving direction of the intermediate transfer belt 8 when viewed from the secondary transfer roller 9.

  The image reading unit 20 includes a scanner lamp that illuminates the document during copying, a scanning optical system equipped with a mirror that changes the optical path of reflected light from the document, and a condensing lens that focuses the reflected light from the document to form an image. And a CCD sensor or the like (both not shown) that converts the imaged image light into an electrical signal, and reads a document image and converts it into image data.

  Next, the image forming units Pa to Pd will be described. There are charging devices 2a, 2b, 2c and 2d for charging the photosensitive drums 1a to 1d and image information on the photosensitive drums 1a to 1d around and below the photosensitive drums 1a to 1d, which are rotatably arranged. The exposure device 4 for exposing the toner, the developing devices 3a, 3b, 3c and 3d for forming toner images on the photosensitive drums 1a to 1d, and the developer (toner) remaining on the photosensitive drums 1a to 1d are removed. Cleaning devices 5a, 5b, 5c and 5d are provided.

  When image data is input from the image reading unit 20, first, the surfaces of the photosensitive drums 1 a to 1 d are uniformly charged by the charging devices 2 a to 2 d, and then a light beam is irradiated according to the image data by the exposure device 4. Then, electrostatic latent images corresponding to the image data from the image reading unit 20 are formed on the photosensitive drums 1a to 1d. Each of the developing devices 3a to 3d includes a developing roller (developer carrying member) disposed so as to face the photosensitive drums 1a to 1d, and a predetermined amount of two-component developer including toners of each color of magenta, cyan, yellow, and black, respectively. Filled. This toner is supplied onto the photosensitive drums 1a to 1d by the developing rollers of the developing devices 3a to 3d, and electrostatically adheres to the electrostatic latent image formed by exposure from the exposure device 4. A toner image is formed.

  The primary transfer rollers 6a to 6d apply an electric field at a predetermined transfer voltage between the primary transfer rollers 6a to 6d and the photosensitive drums 1a to 1d, and magenta, cyan, yellow, and yellow on the photosensitive drums 1a to 1d. A black toner image is primarily transferred onto the intermediate transfer belt 8. These four color images are formed with a predetermined positional relationship predetermined for forming a predetermined full-color image. Thereafter, the toner remaining on the surfaces of the photosensitive drums 1a to 1d is removed by the cleaning devices 5a to 5d in preparation for the subsequent formation of a new electrostatic latent image.

  The intermediate transfer belt 8 is stretched over the driven roller 12 and the drive roller 13, and when the intermediate transfer belt 8 starts to rotate counterclockwise as the drive roller 13 is rotated by a belt drive motor (not shown), The sheet 26 is conveyed from the registration roller pair 14 to the nip portion (secondary transfer nip portion) between the secondary transfer roller 9 and the intermediate transfer belt 8 provided close to the intermediate transfer belt 8 at a predetermined timing. A full color image is secondarily transferred onto the paper 26. The paper 26 onto which the toner image has been transferred is conveyed to the fixing device 7.

  The paper 26 conveyed to the fixing device 7 is heated and pressurized when passing through the nip portion (fixing nip portion) of the fixing roller pair 15 to fix the toner image on the surface of the paper 26, and a predetermined full-color image is formed. It is formed. The sheet 26 on which the full-color image is formed is distributed in the conveyance direction by the conveyance guide member 21 disposed in the branching portion of the sheet conveyance path 19 through the conveyance roller pair 16 and is sent as it is (or sent to the reverse conveyance path 23). After duplex copying, the paper is discharged to the discharge tray 18 via the discharge roller pair 24.

  Specifically, the sheet conveyance path 19 is bifurcated into the left and right forks on the downstream side of the conveyance roller pair 16, and one path (the path branched in the left direction in FIG. 1) communicates with the discharge tray 18. ing. The other path (the path branching rightward in FIG. 1) is configured to communicate with the reverse conveyance path 23.

  Next, the configuration of the image reading unit 20 for reading an image of a document as an electric signal will be described. FIG. 2 is a side sectional view showing the internal structure of the image reading unit 20. In the frame (second frame) 41 of the image reading unit 20, a lamp (light source) 61 that irradiates light toward the image surface of the document, and light from the lamp 61 is efficiently applied to the image surface of the document. Reflection plate 62, a first mirror 63 that directly receives and reflects the reflected light of the document, a second mirror 64 that receives and reflects the reflected light from the first mirror 63, and a reflection from the second mirror 64 A third mirror 65 that receives and reflects light is disposed. The image reading unit 20 is detachable from the main body of the image forming apparatus 100 for maintenance and replacement.

  Further, a lens barrel 66 holding a lens group (not shown) for introducing and collecting the reflected light from the third mirror 65, and the original reflected light collected by the lens group of the lens barrel 66 are received. A line-type CCD (photoelectric conversion member) sensor 67 having a photoelectric conversion element for converting it into an electric signal is disposed on the base plate 70. The optical path of the original reflected light is indicated by a one-dot chain line.

  Here, the lamp 61, the reflector 62 and the first mirror 63 are integrally fixed on the first carriage 68, and the second mirror 64 and the third mirror 65 are integrally fixed on the second carriage 69. ing. These first and second carriages 68 and 69 constitute scanning means and are reciprocally movable in cooperation with each other although they are independent of each other.

  That is, when a document image reading operation is performed by a sheet-through method using an automatic document feeder (not shown), the first carriage 68 is the first image reading region (image reading position) of the automatic reading glass 25a. When the second carriage 69 is held at a predetermined position while being moved and held directly below R1, while the original image reading operation is performed by the original fixing method, the first carriage 68 and the second carriage 69 are While maintaining the optical path length of the reflected light of the original to each other, it reciprocates (scans) under the second image reading region R2 of the manually placed original glass 25b. The first carriage 68 and the second carriage 69 are driven by a carriage drive motor (not shown). The first and second carriages 68 and 69 have a home position directly below a white reference plate (not shown).

  Under such a configuration, the document reflected light irradiated from the lamp 61 and reflected by the image surface of the document is reflected by the first mirror 63 to the third mirror 65 and introduced into the lens group in the lens barrel 66. The light is condensed by the lens group and formed on the CCD sensor 67. The CCD sensor 67 performs photoelectric conversion processing, and the document image is read as an electrical signal.

  Next, the grounding structure of the present invention will be described. FIG. 3 is a cross-sectional view illustrating an embodiment of a grounding structure between the image reading unit 20 and the image forming apparatus 100 main body. The leaf spring member 43 is a grounding member that electrically connects the first frame 40 on the image forming apparatus 100 main body side and the second frame 41 on the image reading unit 20 side to ground the image reading unit 20. It is fixed to the first frame 40 by screws 45. In addition, a compression coil spring 47 for pressing the leaf spring member 43 against the second frame 41 is fixed to the first frame 40 by a second screw 50.

  FIG. 4 is a perspective view of the leaf spring member 43 used in the grounding structure of the present embodiment. As shown in FIG. 4, the plate spring member 43 is integrally formed by bending two portions of a single metal plate, and is divided into a fixed portion 43a, a connecting portion 43b, and a contact portion 43c by a folding line. The fixing portion 43a is a portion for attaching the leaf spring member 43 to the first frame 40, and is formed with a screw hole 46 to which the first screw 45 (see FIG. 3) is fastened. The connecting portion 43b is a portion that connects the fixing portion 43a and the contact portion 43c so as to be elastically deformable, and extends obliquely at a predetermined angle from one side of the connecting portion 43b and the fixing portion 43a. The contact portion 43c is a portion that makes surface contact with the second frame 41, and is formed to be substantially parallel to the fixed portion 43a.

  FIG. 5 is a perspective view of the compression coil spring 47 used in the grounding structure of the present embodiment. As shown in FIG. 5, the end portion 47 a of the compression coil spring 47 fixed to the first frame 40 is processed into a shape (pig tail end) wound inside the compression coil spring 47 in the radial direction, and the end portion 47 a The inner diameter is slightly larger than the shaft diameter of the second screw 50 (see FIG. 3). Accordingly, the end portion 47 a is fastened to the second frame 41 by the second screw 50.

  As a method of fixing the compression coil spring 47 to the first frame 40, in addition to a method of fixing the screw by processing the terminal portion 47a into a pigtail end, for example, a method of fixing the screw of the terminal portion 47a through a washer (washer), For example, a method of press-fitting a boss portion protruding from the first frame 40 into the end portion 47a may be used.

  Further, the end portion 47b of the compression coil spring 47 that presses the contact portion 43c of the leaf spring member 43 has a shape in which the coil end surface (the upper surface of the compression coil spring 47 in FIG. 5) is in contact with the adjacent coil in the coil axial direction (closed end). ). As a result, the end portion 47b can come into contact with the contact portion 43c in a ring shape, and the contact state between the end portion 47b and the contact portion 43c can be stabilized. In addition, if the coil end surface of the end portion 47b is processed into a flatly ground shape (grinding end) so that the end portion 47b comes into surface contact with the contact portion 43c, the contact between the end portion 47b and the contact portion 43c is achieved. The state becomes more stable.

  According to the grounding structure of the present embodiment, the contact portion 43c of the leaf spring member 43 is pressed against the second frame 41 by the compression coil spring 47, so the surface contact between the contact portion 43a and the second frame 41 is ensured. As a result, the image reading unit 20 can be reliably grounded to the first frame 40 of the image forming apparatus 100, and the leaf spring member 43 can be brought into contact with the attachment / detachment operation of the image reading unit 20 or the vibration caused by the movement of the image forming apparatus 100. There is no risk of becoming unstable. Accordingly, it is possible to effectively suppress leakage of electromagnetic noise from the cable that transmits the high-frequency signal of the CCD sensor 67 (see FIG. 2).

  Further, the contact pressure of the leaf spring member 43 can be arbitrarily set by selecting the spring constant of the compression coil spring 47. Furthermore, the contact pressure of the leaf spring member 43 can be maintained without using an expensive spring steel material as the material of the leaf spring member 43, which is advantageous in terms of cost.

  Here, a cylindrical compression coil spring 47 having a constant outer diameter from the end portion 47a to the end portion 47b is used, but a trapezoid spring (the outer diameter from the end portion 47a to the end portion 47b gradually decreases). A conical spring can also be used. It is preferable to use a trapezoidal spring for the compression coil spring 47 because the compression coil spring 47 is less likely to buckle when the contact portion 43c of the leaf spring member 43 is pressed.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, the leaf spring member 43 in which the fixing portion 43a and the contact portion 43c are substantially parallel is used. However, when the opposing surfaces (grounding surfaces) of the two members to be grounded are not parallel, the angle of the opposing surfaces Accordingly, the angle between the fixed portion 43a and the contact portion 43c is adjusted, and the compression coil spring 47 may be disposed so as to press the contact portion 43c vertically.

  In the above-described embodiment, the grounding structure between the image reading unit 20 and the image forming apparatus 100 main body has been described as an example. However, the grounding structure of the present invention includes the exposure device 4, the fixing device 7, and the like. It can be used as a grounding structure for a unit that can be attached to and detached from the main body of the image forming apparatus 100 or a member that can move relative to the main body of the image forming apparatus 100 such as a side cover of the image forming apparatus 100.

  Also, the grounding structure of the present invention. The present invention is not limited to the tandem type color copying machine as shown in FIG. 1, but can be applied to other types of image forming apparatuses such as monochrome copying machines, digital multifunction machines, monochrome and color printers, and ink jet printers. Of course, it can also be applied to the earth structure of electronic equipment.

  The present invention can be used for a grounding structure used in an electronic apparatus such as an image forming apparatus. By utilizing the present invention, it is possible to provide a grounding structure capable of reliably grounding a movable unit or member with a simple configuration, and an electronic apparatus including the same.

20 Image reader 40 First frame (first member)
41 Second frame (second member)
43 leaf spring member 43a fixed portion 43b connecting portion 43c contact portion 45 first screw 47 compression coil spring 47a, 47b end portion 50 second screw 100 image forming apparatus (electronic device)

Claims (4)

A grounding structure of an electronic device for grounding a first member and a second member that are arranged to face each other,
A leaf spring member having a fixed portion fixed to the first member, a contact portion in surface contact with the second member, and an elastically deformable connection portion connecting the contact portion and the fixed portion. When,
A compression coil spring disposed substantially perpendicular to the contact portion, one end of which is fixed to the first member and the other end presses the contact portion toward the second member;
A grounding structure for an electronic device.   The ground structure according to claim 1, wherein the compression coil spring has a closed end processed at a coil end surface that presses the contact portion.   The grounding structure according to claim 1, wherein the compression coil spring has a ground end processed on a coil end surface that presses the contact portion.   The electronic device provided with the grounding structure in any one of Claims 1 thru | or 3.

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