Image forming device

Abstract

To provide a frame configuration of an image forming apparatus that has high rigidity and reduces electromagnetic wave noise emitted to the outside, while reducing the size of the image forming apparatus.SOLUTION: An image forming apparatus of the present invention has a rotatable image carrier, a first sheet metal, a second sheet metal, a frame member, and a motor. The motor is located between the first sheet metal and the second sheet metal. The frame member includes a reinforcement surface extending over an area not provided with the motor; when seen in a rotation axis direction, the reinforcement surface and the motor partially overlap each other; the motor projects beyond the reinforcement surface toward the opposite side of the image carrier. The image forming apparatus has a shield sheet metal that is provided in an area provided with the motor and connected with the second sheet metal and the frame member, the shield sheet metal covering part of the motor on the opposite side of the image carrier when seen in the rotation axis direction.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] Image forming devices such as printers and copiers are equipped with many components, such as circuit boards and motors. From the perspectives of reducing the installation space required for image forming devices, reducing costs and saving resources during manufacturing, there has long been a demand for smaller and lighter image forming devices.

[0003] Patent Document 1 describes a configuration in which the image forming apparatus is made smaller by devising the layout positions of components such as a low-voltage power supply unit, a high-voltage power supply unit, and a motor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-20932 Summary of the Invention [Problem to be solved by the invention]

[0005] The configuration described in Patent Document 1 fully satisfied the size and weight requirements for image forming devices at the time, but in recent years, there has been a demand for even smaller and lighter devices. To further reduce the size and weight of image forming devices, it has been considered to reduce the size of the metal plates that make up the frame of the image forming device. However, this reduces the rigidity of the frame, which can cause shaking and vibration when an image is formed on a recording material, potentially reducing the quality of the image formed on the recording material.

[0006] Furthermore, electronic components such as motors generate electromagnetic waves. As image forming devices become smaller and lighter, the area of ​​the metal plate covering the motor becomes smaller, which can result in a large amount of electromagnetic noise being emitted outside the image forming device. Because electromagnetic noise can affect electronic devices around the image forming device, it is desirable to reduce the amount of electromagnetic noise emitted outside as much as possible.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a frame structure for an image forming apparatus that is highly rigid and suppresses electromagnetic noise emitted to the outside, while reducing the size of the image forming apparatus. [Means for solving the problem]

[0008] In order to achieve the above object, an image forming apparatus of the present invention includes a rotatable image carrier, a first metal plate supporting a first end of the image carrier in a direction of a rotation axis of the image carrier, a second metal plate supporting a second end of the image carrier opposite to the first end in the direction of the rotation axis, a frame member provided between the first metal plate and the second metal plate in the direction of the rotation axis and connected to each of the first metal plate and the second metal plate, and a motor provided on the second metal plate for driving at least one of the image carrier, a conveying member for conveying a recording material, and a process member for forming an image on the recording material, wherein the motor is The frame member is located between the first metal plate and the second metal plate in the direction of the rotation axis, and has a reinforcing surface that extends over an area in the direction of the rotation axis where the motor is not provided, and when viewed in the direction of the rotation axis, the reinforcing surface and the motor partially overlap, and the motor protrudes beyond the reinforcing surface toward the opposite side of the image carrier, and is characterized by having a shielding metal plate that is provided in the area in the direction of the rotation axis where the motor is provided and is connected to each of the second metal plate and the frame member, and the shielding metal plate covers a portion of the motor on the opposite side of the image carrier when viewed in the direction of the rotation axis. [Effects of the Invention]

[0009] As described above, according to the present invention, it is possible to provide a frame configuration for an image forming apparatus that is compact, has high rigidity, and suppresses electromagnetic noise emitted to the outside. [Brief explanation of the drawings]

[0010] [Figure 1] Perspective view of an image forming apparatus [Figure 2] Cross-sectional view of an image forming apparatus [Figure 3] A perspective view showing the frame structure and board position [Figure 4] A perspective view showing the frame configuration [Figure 5] Cross-sectional view showing the frame structure [Figure 6] A perspective view showing the frame structure and shielding sheet metal [Figure 7] Cross-section showing the frame structure and shielding sheet metal [Figure 8] Front view showing the frame structure and shielding sheet metal [Figure 9] Perspective view of the shield metal plate DETAILED DESCRIPTION OF THE INVENTION

[0011] The following describes in detail exemplary embodiments of the present invention with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiments.

[0012] Example 1 [Overall configuration of image forming device] The overall configuration of the image forming apparatus 1 in this embodiment will be described. The image forming apparatus 1 in this embodiment is a monochrome laser beam printer that uses an electrophotographic process, and forms an image with a developer (toner) on a recording material P in accordance with image information transmitted from an external device such as a personal computer. Examples of the recording material P include recording paper, label paper, overhead projector sheets, and cloth.

[0013] In the following description, the height direction of the image forming apparatus 1 (the direction opposite to the vertical direction) when the image forming apparatus 1 is installed on a horizontal surface is referred to as the Z direction. The direction that intersects with the Z direction and is parallel to the rotation axis direction (main scanning direction) of the photosensitive drum 11, which will be described later, is referred to as the X direction. The direction that intersects with the X and Z directions is referred to as the Y direction. The X, Y, and Z directions preferably intersect perpendicularly with each other. For convenience, the positive side in the X direction is referred to as the right side and the negative side is referred to as the left side; the positive side in the Y direction is referred to as the front side or front side and the negative side is referred to as the rear side or back side; and the positive side in the Z direction is referred to as the upper side and the negative side is referred to as the lower side.

[0014] FIG. 1 shows a perspective view of image forming apparatus 1, and FIG. 2 is a diagram illustrating the internal configuration of image forming apparatus 1 as viewed from the X direction (the direction of the rotation axis of photosensitive drum 11). FIG. 2 shows only the components related to the image formation process. In FIG. 1, image forming apparatus 1 has a feed cassette 4 that stores recording materials P and an output tray 14 on which the discharged recording materials P are stacked. When feed cassette 4 is inserted into feed opening 81, the recording materials P stored in feed cassette 4 become ready to be fed into image forming apparatus 1. In addition, feed cassette 4 can be pulled out from feed opening 81 in the Y direction, allowing the user to replenish recording materials P. The recording materials P that have been fed from feed cassette 4 and on which images have been formed are discharged from output opening 15 in the discharge direction (positive direction of the Y axis) shown in FIG. 1 and stacked on output tray 14.

[0015] A front cover 70 is provided on a portion of the end face (part of the front face) of the image forming apparatus 1 on the downstream side in the discharge direction, covering a circuit board 100 (described later). An exterior cover 71 is provided on a portion of the front face other than the portion where the front cover 70 is provided, as well as on the side and top faces of the image forming apparatus 1. The front cover 70, the exterior cover 71, and the discharge tray 14 described above together form a housing 79 of the image forming apparatus 1. A rear cover (not shown) is provided on the rear side of the image forming apparatus 1, and this rear cover also forms part of the housing 79. Here, the housing 79 is a member that covers the entire image forming apparatus 1, and includes an optical box 50 (described later) and other components inside. The above-mentioned feed opening 81 and discharge opening 15 are openings formed in part of the housing 79. The recording material P is inserted into the image forming apparatus 1 through the feed opening 81 and is discharged to the outside of the image forming apparatus 1 through the discharge opening 15.

[0016] The flow of an image forming operation on a recording material P will be described using FIG. 2. The image forming operation is mainly performed by the image forming unit 45 (photosensitive drum 11, charging roller 17, developing roller 12, and storage section 18), the optical box 50, the transfer roller 7, and the fixing device 9. First, when image information is transmitted to the image forming apparatus 1, the photosensitive drum 11, which is a rotatable image carrier, is rotated in the direction of arrow R at a predetermined peripheral speed (process speed) based on a print start signal. The optical box 50 irradiates the photosensitive drum 11 with a laser beam based on the input image information. The optical box 50 is a box-shaped unit that includes components such as a laser oscillator that outputs the laser beam, a polygon mirror and lens for irradiating the photosensitive drum 11 with the laser beam, and a scanner motor for rotating the polygon mirror. The photosensitive drum 11 is pre-charged by the charging roller 17, and an electrostatic latent image is formed on the photosensitive drum 11 when irradiated with the laser beam. Thereafter, the toner contained in the container 18 is conveyed to the photosensitive drum 11 by the developing roller 12, whereby the electrostatic latent image is developed and a toner image is formed on the photosensitive drum 11.

[0017] In parallel with the image formation process described above, recording materials P are fed from the feed cassette 4. A pickup roller 3, a feed roller 5a, and a pair of conveying rollers 5c are provided on the conveying path 19 of the image forming apparatus 1. The pickup roller 3 (feeding member) comes into contact with the uppermost recording material P stored in the feed cassette 4, and the roller itself rotates to feed the recording material P in the feeding direction (the negative Y-axis direction). The feed roller 5a and the separation roller 5b that comes into pressure contact with it form a separation nip. If multiple sheets of recording materials P are fed into the separation nip due to the influence of friction between the recording materials P, the feed roller 5a and the separation roller 5b separate the multiple sheets of recording materials P and feed only the uppermost one downstream.

[0018] The recording material P fed from the feeding cassette 4 is conveyed by a pair of conveying rollers 5c through a conveying path 19 toward a transfer roller 7. A transfer bias is applied to the transfer roller 7, so that the toner image formed on the photosensitive drum 11 is transferred onto the recording material P. The recording material P onto which the toner image has been transferred by the transfer roller 7 is heated and pressurized by a fixing device 9, so that the toner image is fixed onto the recording material P. The fixing device 9 is composed of a heating roller 9a incorporating a fixing heater 9c, and a pressure roller 9b urged toward the heating roller 9a. Then, the recording material P onto which the toner image has been fixed is discharged onto a discharge tray 14 by a pair of discharge rollers 10.

[0019] When an image is formed on both sides of the recording material P, the pair of discharge rollers 10 switches back the recording material P with the image formed on the first side, thereby guiding the recording material P to the double-sided conveying path 16. The recording material P guided to the double-sided conveying path 16 is conveyed again toward the transfer roller 7 by the pair of double-sided conveying rollers 5d. After an image is formed on the second side of the recording material P by the transfer roller 7, the recording material P is discharged outside the apparatus by the pair of discharge rollers 10. After the toner image is transferred to the recording material P, any toner remaining on the photosensitive drum 11 is cleaned by the cleaning unit 13.

[0020] As shown in Fig. 2, the image forming apparatus 1 has a circuit board 100. The circuit board 100 is composed of a printed circuit board 101 made of an insulating material and electronic component groups 111 and 121 soldered to the printed circuit board 101. The printed circuit board 101 is provided with conductive wiring, so that the electronic component groups 111 and 121 are electrically connected. The circuit board 100 is equipped with a converter circuit (not shown) that rectifies a voltage supplied from outside the image forming apparatus 1 and converts the voltage to obtain a predetermined voltage value required for the image formation process.

[0021] 2, the circuit board 100 is oriented such that the surface of the printed circuit board 101 on which the electronic component groups 111 and 121 are mounted intersects with the ejection direction. Furthermore, the printed circuit board 101 is provided between the front cover 70 and the optical box 50 in the ejection direction. The electronic component groups 111 and 121 are provided on the surface of the printed circuit board 101 facing the optical box 50.

[0022] [Frame Configuration] The frame structure of the image forming apparatus 1 will be described in detail with reference to Figures 3 to 5. Figure 3 is a perspective view of the image forming apparatus 1 equipped with a circuit board 100, and unlike Figure 1, the front cover 70 and the exterior cover 71 are omitted. Note that Figure 3 also newly shows a supply unit 200 for replenishing toner. In the image forming apparatus 1 of this embodiment, a user or service person can attach a supply container (not shown) to the supply unit 200. Then, developer can be replenished from the supply unit 200, which is connected to the storage unit 18 inside the apparatus. Note that a user or service person can access the supply unit 200 by opening the discharge tray 14 upward.

[0023] As shown in Fig. 3, the circuit board 100 is installed on the front side, and the optical box 50 and the drive motor 60 are provided further back (on the negative side in the Y direction) of the circuit board 100. Note that the optical box 50 and the drive motor 60 are shown by dotted lines in Fig. 3 because they are not actually visible.

[0024] The photosensitive drum 11, charging roller 17, developing roller 12, pickup roller 3, feed roller 5a, conveying roller pair 5c, transfer roller 7, pressure roller 9b, and discharge roller pair 10 described above are rotated by a single drive motor 60. The driving force from the drive motor 60 is transmitted to the respective process members and conveying members via a gear train (not shown) provided on the right side panel frame 72.

[0025] As described above, the drive motor 60 applies a heavy load to the motor shaft because it drives many components within the image forming apparatus 1. A DC brush motor is used for the drive motor 60 in this embodiment because it is inexpensive and capable of rotating and driving a heavy load.

[0026] A DC brush motor rotates when the motor brushes come into contact with a commutator, which is divided in the direction of rotation, causing a continuous current to flow through the coil. A characteristic of DC brush motors is that sparks are generated when the motor brushes begin to come into contact with the commutator, emitting radio frequency electromagnetic noise. Radio frequency electromagnetic noise can cause noise in audio equipment or malfunction of meters. Because electromagnetic noise can cause interference with equipment installed around the image forming apparatus 1, it is necessary to prevent radio frequency electromagnetic noise from leaking to the outside.

[0027] FIG. 4 is a perspective view showing the frame configuration of the image forming apparatus 1 with the circuit board 100 removed. As shown in FIG. 4, the image forming apparatus 1 has a right side frame 72 (first metal plate), a left side frame 73 (second metal plate), a base frame 74, a bridging frame 75 (frame member), and a lower frame 76. The right side frame 72 supports the right end (first end) of the photosensitive drum 11 in the X direction, and the left side frame 73 supports the left end (second end) of the photosensitive drum 11 in the X direction. The base frame 74 is provided on the bottom surface and supports the right side frame 72 and the left side frame 73 from below. The lower frame 76 is provided between the right side frame 72 and the left side frame 73 and extends toward the rear side approximately in the XY plane. The right side frame 72, the left side frame 73, the bridging frame 75, and the lower frame 76 are made of metal, and the base frame 74 is a resin member.

[0028] Bent portions 72a, 73a provided for reinforcement are formed at the Y-direction ends of the right side plate frame 72 and the left side plate frame 73. The bent portion 72a is bent toward the positive side of the X direction so as to be approximately parallel to the XZ plane, and the bent portion 73a is bent toward the negative side of the X direction so as to be approximately parallel to the XZ plane.

[0029] The bridging frame 75 is provided between the right side plate frame 72 and the left side plate frame 73 in the X direction, and supports the optical box 50 via the support base 51. The bridging frame 75 has a support surface 75a that supports the optical box 50, a reinforcing surface 75b formed by bending the support surface 75a downward on the front side, and a reinforcing surface 75c formed by bending the support surface 75a upward on the front side. The support surface 75a extends approximately in the XY plane, and the reinforcing surfaces 75b and 75c extend approximately in the XZ plane.

[0030] The reinforcing surface 75b of the bridging frame 75 is arranged to overlap a portion of the bent portion 73a of the left side plate frame 73 when viewed from the front side, and the back side of the reinforcing surface 75b is welded to the bent portion 73a, thereby connecting the bridging frame 75 and the left side plate frame 73. In addition, the reinforcing surface 75c of the bridging frame 75 is arranged to overlap a portion of the bent portion 72a of the right side plate frame 72 when viewed from the front side, and the reinforcing surface 75c is welded to the bent portion 72a, thereby connecting the bridging frame 75 and the right side plate frame 72.

[0031] Furthermore, in region R1, the support surface 75a of the bridging frame 75 is connected to the right side plate frame 72. A plurality of protrusions 750-1 that fit into openings 720-1 formed in the right side plate frame 72 are provided at the end of the support surface 75a on the positive side in the X direction. In FIG. 4, some of the openings 720-1 are not actually visible and are therefore shown with dotted lines. Furthermore, in region R3, the support surface 75a of the bridging frame 75 is connected to the left side plate frame 73. A protrusion (not shown) similar to protrusion 750-1 is provided at the end of the support surface 75a on the negative side in the X direction, and fits into an opening (not shown) formed in the left side plate frame 73.

[0032] As will be described in more detail below, the bridging frame 75 includes a support surface 75a, a reinforcing surface 75b, and a reinforcing surface 75c, as well as a reinforcing surface 75d (not shown in FIG. 4) formed by bending the support surface 75a downward on the back side. In region R2, the reinforcing surface 75d of the bridging frame 75 is connected to the right side plate frame 72. A protrusion 750-2 is provided at the end of the reinforcing surface 75d on the positive side in the X direction, which fits into an opening 720-2 formed in the right side plate frame 72. In FIG. 4, part of the opening 720-2 is shown by a dotted line because it is not actually visible. Furthermore, in region R4, the reinforcing surface 75d of the bridging frame 75 is connected to the left side plate frame 73. A protrusion (not shown) similar to the protrusion 750-2 is provided at the end of the reinforcing surface 75d on the negative side in the X direction, which fits into an opening (not shown) formed in the left side plate frame 73.

[0033] The drive motor 60 is provided on the right side plate frame 72, and is disposed between the right side plate frame 72 and the left side plate frame 73 in the X direction. The rotation shaft 60a of the drive motor 60 passes through the right side plate frame 72 and is exposed on the positive side in the X direction. In addition to the above-mentioned bent portion 72a, the right side plate frame 72 also has bent portions 72b and 72c, which are located closer to the front than the bent portion 72a.

[0034] 5 is a cross-sectional view of the image forming apparatus 1 cut along the YZ plane at the position where the optical box 50 is provided. That is, it shows a cross-sectional view when cross section P1 in FIG. 4 is viewed in the X direction (the direction of the rotation axis of the photosensitive drum 11). Note that because FIG. 5 shows a view of cross section P1 when viewed from the negative side to the positive side in the X direction, the left side plate frame 73 is not shown.

[0035] 5, the position of the drive motor 60 in the front-rear direction within the image forming apparatus 1 is forward of the photosensitive drum 11 and rear of the circuit board 100, and is determined by the positions of these two components. Furthermore, a portion of the drive motor 60 protrudes forward beyond the bent portion 72a of the right side plate frame 72. Therefore, the bent portion 72a for reinforcing the right side plate frame 72 cannot be provided near the drive motor 60. Therefore, the bent portion 72a is present only in the region above the drive motor 60.

[0036] As described above, the bent portion 72a is provided to reinforce the right side plate frame 72. Therefore, the area of ​​the right side plate frame 72 where the drive motor 60 is attached (the mounting surface of the drive motor 60) has lower rigidity than other areas.

[0037] As shown in FIG. 5, the drive motor 60 is positioned in the image forming apparatus 1 in the up-down direction below the support surface 75a of the bridging frame 75 and above the lower frame .

[0038] A pinion gear (not shown) is attached to the rotating shaft 60a (shown in FIG. 4) of the drive motor 60. The pinion gear meshes with another gear and receives force in the radial direction of the rotating shaft 60a. Therefore, if the rigidity of the mounting surface of the drive motor 60 is low, the mounting surface will be deformed by the driving force of the drive motor 60. If the mounting surface deforms and the mounting posture of the drive motor 60 changes, the meshing with the pinion gear deteriorates, causing uneven rotation of the gear. As a result, image defects such as uneven shading at a specific pitch occur in the image formed on the recording material P. In other words, if the rigidity of the mounting surface of the drive motor 60 is low, there is a risk of image quality deteriorating.

[0039] In order to prevent the drive motor 60 from protruding forward beyond the bent portion 72a of the right side plate frame 72, one method is to increase the size of the right side plate frame 72, but increasing the size of the right side plate frame 72 results in adverse effects such as increased costs and weight.

[0040] 4, the bridging frame 75 has reinforcing surfaces 75b and 75c formed by bending the support surface 75a toward the front side. Reinforcing surface 75b is formed by bending the support surface 75a downward, and reinforcing surface 75c is formed by bending the support surface 75a upward. If the entire support surface 75a is bent upward in the X direction, part of the bridging frame 75 will interfere with the optical box 50. If the entire support surface 75a is bent downward in the X direction, part of the bridging frame 75 will interfere with the drive motor 60.

[0041] As shown in Figure 5, the reinforcing surface 75b partially overlaps with the drive motor 60. This also shows that if the entire support surface 75a were bent downward, a portion of the bridging frame 75 would interfere with the drive motor 60. If the entire support surface 75a were bent downward to avoid interference between a portion of the bridging frame 75 and the drive motor 60, the bridging frame 75 would cover the drive motor 60 from the front side. With this configuration, after the bridging frame 75 is welded to the right side plate frame 72 and the left side plate frame 73, the drive motor 60 cannot be attached or detached to the right side plate frame 72, significantly reducing assembly and service replaceability.

[0042] For this reason, in the region in the X direction where drive motor 60 is not present, support surface 75a is bent downward to form reinforcing surface 75b, and in the region where drive motor 60 is present, support surface 75a is bent upward to form reinforcing surface 75c. In other words, the bend in support surface 75a of bridging frame 75 is broken halfway, making it less rigid than if the bend were continuous. The portion where the bend is broken is near optical box 50, and if the rigidity at this location decreases, it will become difficult to stably support optical box 50.

[0043] As described above, the bridging frame 75 has a reinforcing surface 75d formed by bending the support surface 75a downward on the rear side. The reinforcing surface 75d extends substantially in the XZ plane and is located between the photosensitive drum 11 and the drive motor 60 in the Y direction. That is, in FIG. 5, the bridging frame 75 has a substantially U-shaped configuration including the support surface 75a, the reinforcing surface 75b, and the reinforcing surface 75d. Note that the reinforcing surface 75c is not shown in FIG. 5 because it is hidden from view by the optical box 50. The bridging frame 75 also has an attachment surface 75e formed by further bending the reinforcing surface 75d toward the rear side. The attachment surface 75e is welded to the lower frame 76, thereby fixing the bridging frame 75 to the lower frame 76.

[0044] High rigidity is required for the bridging frame 75 to support the optical box 50. If the bridging frame 75 were not rigid enough, the optical box 50 would be more susceptible to vibration due to external vibrations or vibrations caused by the drive motor 60, resulting in blurring of the exposure position and image degradation. To increase its rigidity, the bridging frame 75 that supports the optical box 50 has three main bent portions to provide the reinforcing surfaces 75b, 75c, and 75d described above, and is shaped to increase the second moment of area. In other words, the rigidity of the bridging frame 75 is ensured by bending a single metal sheet.

[0045] [Shield metal placement and shape] The arrangement and fastening method of the shielding sheet metal 77, which are characteristic of the present invention, will now be described with reference to Figures 6 to 9. First, the arrangement of the shielding sheet metal 77 and the method of shielding electromagnetic noise radiated from the drive motor 60 will be described.

[0046] As mentioned above, the DC brush motor used in this embodiment has the characteristic of emitting electromagnetic noise. In this embodiment, the drive motor 60, which is the noise radiation source, is covered with a metal plate that is impermeable to electromagnetic waves, thereby preventing the electromagnetic noise from escaping outside the image forming apparatus 1. In order to suppress the emission of this electromagnetic noise, a new shielding metal plate 77 is added.

[0047] FIG. 6 is a perspective view of the frame configuration of FIG. 4 to which a shielding metal plate 77 has been added. The shielding metal plate 77 has a base surface 77a, a curved surface 77b, and a shielding surface 77c. The shielding metal plate 77 is made of a single metal plate and has been subjected to a drawing process. The base surface 77a and the shielding surface 77c both extend substantially in the XZ plane, with the shielding surface 77c being located on the positive side of the Y direction relative to the base surface 77a. The curved surface 77b connects the base surface 77a and the shielding surface 77c and is curved by drawing so as to bulge out in the positive side of the Y direction. The shielding metal plate 77 covers a portion of the drive motor 60 and serves to suppress the emission of electromagnetic noise.

[0048] As will be described in detail later, a shielding metal plate 77 is provided in the region in the X direction where the drive motor 60 is provided, and is connected to both the bridge frame 75 and the right side plate frame 72 .

[0049] 7 is a cross-sectional view of the image forming apparatus 1 cut along the YZ plane at the position where the drive motor 60 is provided. That is, it shows a cross-sectional view of cross section P2 in FIG. 6 as seen in the X direction (the direction of the rotation axis of the photosensitive drum 11). Note that, as in FIG. 5, the left side plate frame 73 is not shown.

[0050] As shown in Fig. 7, the drive motor 60 is surrounded in the Z direction by the support surface 75a of the bridging frame 75 and the lower frame 76. In addition, the drive motor 60 is surrounded in the Y direction by the reinforcing surface 75d of the bridging frame 75, a shielding sheet metal 77, and a board stay 78. The board stay 78 is a metal sheet metal, and is provided outside the circuit board 100 (on the positive side in the Y direction). In addition, as shown in Figs. 4 and 6, the drive motor 60 is surrounded in the X direction by the right plate frame 72 and the left plate frame 73. In this way, electromagnetic noise emitted from the drive motor 60 is shielded in all directions.

[0051] As described above, the drive motor 60 is disposed so as to protrude forward (toward the opposite side from the photosensitive drum 11) from the bent portion 72a of the right side plate frame 72 and the reinforcing surface 75b (not shown in FIG. 7) of the bridging frame. Therefore, the shielding sheet metal 77 has a three-dimensional shape formed by squeezing a portion forward, and covers the front side of the drive motor 60.

[0052] At this time, the shielding sheet metal 77 and the circuit board 100 need to be spaced a predetermined distance apart so that the current flowing through the circuit board 100 does not leak to the shielding sheet metal 77, and the drawing height position of the shielding sheet metal 77 is determined by this distance. Therefore, the shielding sheet metal 77 is unable to cover the lower front part of the drive motor 60. The area that is not covered by the shielding sheet metal 77 is covered by the board stay 78.

[0053] By attaching the shielding metal plate 77 close to the drive motor 60 and covering the upper front part of the drive motor 60, there is no need to extend the board stay 78 upward. In other words, the electromagnetic noise that needs to be shielded by the board stay 78 can be limited to the electromagnetic noise emitted from the lower part of the drive motor 60, so the board stay 78 can be made smaller, leading to weight and cost reductions for the image forming apparatus 1.

[0054] Next, the method for fastening the shielding metal plate 77 and the rigidity of the frame will be described with reference to Figures 8 and 9. Figure 8 is a front view of a portion of the image forming apparatus 1 to which the shielding metal plate 77 is attached, and Figure 9 is a perspective view of the shielding metal plate 77.

[0055] As described above, the bridging frame 75 has its bent portion cut off midway in the X direction to avoid interference with the drive motor 60, and the separation into reinforcing surfaces 75b and 75c results in locally reduced rigidity. In addition, the bent portion 72a of the right side plate frame 72 is also cut off by the seating surface of the drive motor 60, resulting in locally reduced rigidity.

[0056] In other words, the reinforcing surface 75b is not formed over the entire X-direction area of ​​the bridging frame 75, and the bent portion 72a is not formed over the entire Z-direction area of ​​the right side plate frame 72. In other words, compared to a configuration in which bent portions are formed continuously over the entire area, the bridging frame 75 and the right side plate frame 72 have locally reduced rigidity.

[0057] As shown in Fig. 8, a bent portion 77-1 is formed in the left-hand region of the base surface 77a of the shielding sheet metal 77. As shown in Fig. 9, the bent portion 77-1 is configured to be partially bent toward the rear side. This bent portion 77-1 is inserted into a square hole formed in the reinforcing surface 75b of the bridging frame 75, thereby determining the vertical positions of the shielding sheet metal 77 and the bridging frame 75. In this state, the shielding sheet metal 77 is fastened to the reinforcing surface 75b of the bridging frame 75 with screws B1.

[0058] Furthermore, bent portions 77-2, 77-3, and 77-4 are formed in the right-hand region of the base surface 77a of the shielding sheet metal 77. As shown in Fig. 9, the bent portions 77-2, 77-3, and 77-4 are configured to be partially bent toward the rear surface. These bent portions 77-2, 77-3, and 77-4 are inserted into square holes formed in the reinforcing surface 75c (shown in Fig. 4) of the bridging frame 75, thereby determining the vertical and horizontal positions of the shielding sheet metal 77 and the bridging frame 75. In this state, the shielding sheet metal 77 is fastened to the reinforcing surface 75c of the bridging frame 75 with screws B2 and B3.

[0059] Furthermore, a bent portion 77-5 is formed in the upper region of the shielding surface 77c of the shielding sheet metal 77. As shown in Fig. 9, the bent portion 77-5 is configured to be partially bent toward the rear side. This bent portion 77-5 is inserted into a square hole formed in the bent portion 72b (shown in Fig. 4) of the right side frame plate 72, thereby determining the left-right positions of the shielding sheet metal 77 and the right side frame plate 72. In this state, the shielding sheet metal 77 is fastened to the bent portion 72b of the right side frame plate 72 with a screw B5.

[0060] Furthermore, a bent portion 77-6 is formed in the area below the shield surface 77c of the shielding sheet metal 77. As shown in Fig. 9, the bent portion 77-6 is configured to be partially bent toward the rear side. This bent portion 77-6 is inserted into a square hole formed in the bent portion 72c (shown in Fig. 4) of the right side frame plate 72, thereby determining the left-right positions of the shielding sheet metal 77 and the right side frame plate 72. In this state, the shielding sheet metal 77 is fastened to the bent portion 72c of the right side frame plate 72 with a screw B4.

[0061] Although the bridge frame 75 and the right side plate frame 72 each have low rigidity as individual components, their rigidity can be maintained high by providing a shielding metal plate 77 between them to block electromagnetic noise. In other words, the shielding metal plate 77 serves to block electromagnetic noise from the drive motor 60 and to improve the rigidity of the frame of the image forming apparatus 1.

[0062] As described above, according to this embodiment, it is possible to provide a frame configuration for an image forming apparatus that is compact, has high rigidity, and suppresses electromagnetic noise from being emitted to the outside.

[0063] More specifically, by providing a shielding metal plate 77 to shield electromagnetic noise emitted from the drive motor 60, it is possible to maintain high rigidity of the frame and suppress vibration of the optical box 50 and deformation of the mounting surface of the drive motor 60. [Explanation of symbols]

[0064] 1. Image forming device 11 Photosensitive drum 60 Drive motor 72 Right side panel frame 73 Left side board frame 75 Bridging Frame 77 Shield Plate

Claims

1. a rotatable image carrier; a first metal plate supporting a first end of the image carrier in a direction of a rotation axis of the image carrier; a second metal plate supporting a second end of the image carrier opposite to the first end in the rotation axis direction; a frame member provided between the first metal plate and the second metal plate in the rotation axis direction and connected to each of the first metal plate and the second metal plate; an image forming apparatus including a motor provided on the first metal plate for driving at least one of the image carrier, a conveying member for conveying a recording material, and a process member for forming an image on the recording material, the motor is located between the first metal plate and the second metal plate in the direction of the rotation axis, the frame member has a reinforcing surface extending over an area in the rotation axis direction where the motor is not provided, the reinforcing surface and the motor partially overlap each other when viewed in the rotation axis direction, and the motor protrudes beyond the reinforcing surface toward an opposite side to the image carrier, An image forming apparatus characterized in that it has a shielding metal plate provided in the area in the direction of the rotation axis where the motor is provided, connected to each of the first metal plate and the frame member, and the shielding metal plate covering a portion of the motor on the opposite side of the image carrier when viewed in the direction of the rotation axis.

2. an exposure means for exposing the image carrier to light, 2. The image forming apparatus according to claim 1, wherein the frame member has a support surface extending in the direction of the rotation axis, and the frame member supports the exposure unit on the support surface.

3. 3. The image forming apparatus according to claim 2, wherein the frame member has a second reinforcing surface extending in the direction of the rotation axis, and when viewed in the direction of the rotation axis, the second reinforcing surface is located between the motor and the image carrier.

4. 4. The image forming apparatus according to claim 3, wherein the frame member has a third reinforcing surface extending over the area in the direction of the rotation axis where the motor is provided, and the shielding metal plate is fixed to the reinforcing surface and the third reinforcing surface.

5. 5. The image forming apparatus according to claim 4, wherein the frame member is a single piece of metal plate, and the reinforcing surface, the support surface, the second reinforcing surface, and the third reinforcing surface are formed by bending the single piece of metal plate.

6. The image forming apparatus described in claim 4 or 5, characterized in that the support surface of the frame member has a protrusion protruding in the rotation axis direction, and the frame member is connected to each of the first sheet metal and the second sheet metal by fitting the protrusion into openings formed in the first sheet metal and the second sheet metal.

7. The image forming apparatus described in claim 4 or 5, characterized in that the first sheet metal and the second sheet metal each have a bending portion, and the reinforcing surface of the frame member is fixed to the bending portion of the second sheet metal, and the third reinforcing surface of the frame member is fixed to the bending portion of the first sheet metal, thereby connecting the frame member to each of the first sheet metal and the second sheet metal.

8. When viewed in the direction of the rotation axis, the motor protrudes beyond the bent portion of the first metal plate toward an opposite side to the image carrier, 8. The image forming apparatus according to claim 7, wherein the first metal plate has a second bent portion provided vertically below the bent portion.

9. 9. The image forming apparatus according to claim 8, wherein the shielding metal plate is fixed to the reinforcing surface and the third reinforcing surface of the frame member, and is fixed to the second bent portion of the first metal plate.

10. 10. The image forming apparatus according to claim 1, wherein the shielding metal plate is a single metal plate, and a portion of the shielding metal plate is curved to match the shape of the motor.

Images