Image forming apparatus

Abstract

To prevent vibration of an exposure unit and locate the exposure unit at an appropriate position, while reducing cost.SOLUTION: An image forming apparatus comprises: a rotating image carrier; a metal frame member that includes a support face; an exposure unit that irradiates the surface of the image carrier with light to form an electrostatic latent image, the exposure unit arranged such that the irradiation direction of the light with respect to the image carrier is inclined with respect to the support face when seen in the axis direction of rotation of the image carrier; a metal support member that supports the exposure unit in an attitude inclined with respect to the support face; and a resin positioning member that is in contact with the exposure unit and determines the position of the exposure unit. The support face of the frame member is in contact with at least one of the support member and the positioning member. The exposure unit is attached to the frame member with the support member and the positioning member therebetween.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus that forms an image on a sheet. [Background technology]

[0002] Generally, electrophotographic image forming apparatuses include an exposure unit (also called a laser scanner unit) that irradiates a charged photosensitive drum with laser light to form an electrostatic latent image on the photosensitive drum. The exposure unit is attached to a support frame such as a metal sheet metal stay that connects a pair of side plates arranged opposite each other at both ends in the width direction of the image forming apparatus (Patent Document 1). This is because vibration of the exposure unit during image formation can cause image defects, so by attaching the exposure unit to a highly rigid sheet metal stay, vibration of the exposure unit can be suppressed.

[0003] Conventionally, in order to attach an exposure unit to a sheet metal stay at a predetermined position during assembly of an image forming apparatus, a boss having a shaft is formed on one of the exposure unit and the sheet metal stay, and a boss hole that can fit into the boss is formed on the other. These bosses and boss holes are formed so that the shaft and the hole are oriented in the same direction so that the irradiation angle of the laser light from the exposure unit to the photosensitive drum is a predetermined angle when the exposure unit is attached to the sheet metal stay. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-042055 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in the past, the exposure unit and the metal stay were mounted in an appropriate position relative to the metal stay so that the laser beam irradiation angle was a predetermined angle using bosses and boss holes pre-formed on the exposure unit and the metal stay. However, depending on the model of the image forming apparatus or manufacturing errors, the positions of the exposure unit and the photosensitive drum within the image forming apparatus body may differ. In such cases, in the past, in order to properly position the exposure unit, it was necessary to prepare multiple types of exposure units and metal stays with different boss shaft directions or boss hole directions. In other words, the exposure unit and metal stay could not be shared across multiple models, which was costly.

[0006] SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image forming apparatus that can suppress vibration of an exposure unit and position the exposure unit at an appropriate position while reducing costs. [Means for solving the problem]

[0007] An image forming apparatus according to one embodiment of the present invention comprises a rotating image carrier, a metal frame member having a support surface, an exposure unit that forms an electrostatic latent image by irradiating light onto the surface of the image carrier, the exposure unit being arranged so that the direction of light irradiation onto the image carrier is inclined relative to the support surface when viewed in the direction of the rotation axis of the image carrier, a metal support member that supports the exposure unit in an inclined position relative to the support surface, and a resin positioning member that contacts the exposure unit and positions the exposure unit, characterized in that the support surface of the frame member contacts at least one of the support member and the positioning member, and the exposure unit is attached to the frame member via the support member and the positioning member. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress vibration of the exposure unit and position the exposure unit at an appropriate position while reducing costs. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an external perspective view showing an image forming apparatus. [Figure 2] FIG. 1 is a schematic diagram illustrating a configuration of an image forming apparatus. [Figure 3] FIG. 2 is a perspective view showing a support frame and an exposure unit. [Figure 4] FIG. 10A is a left side view illustrating the support of the support frame body, and FIG. 10B is an enlarged cross-sectional view showing contact points on the left rear side. [Figure 5] FIG. 10A is a right side view illustrating the support of the support frame body, and FIG. 10B is an enlarged cross-sectional view showing a contact point on the right rear side. [Figure 6] FIG. 2 is a perspective view showing the exposure unit, the mounting attachment, the exposure support member, and the metal stay. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. 10 is a top view showing the exposure unit attached to the metal stay by the attachment. [Figure 11] 4A and 4B are perspective views for explaining the first wire spring, in which FIG. 4A shows the first wire spring including a wire spring holding member, and FIG. 4B shows the first wire spring without the wire spring holding member. [Figure 12] FIG. 10 is a perspective view illustrating a second wire spring. [Figure 13] FIG. 10 is a top view illustrating the arrangement of the exposure support member relative to the metal stay. [Figure 14] FIG. 4 is a left side view for explaining the arrangement of the exposure unit. [Figure 15] FIG. 3 is a cross-sectional view for explaining an exposure unit and electrical components mounted on a circuit board. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail the 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.

[0011] <Image forming device> First, an overview of the image forming apparatus of this embodiment will be described with reference to Figures 1 and 2. Figure 1 is an external perspective view showing the image forming apparatus 1 according to this embodiment. Figure 2 is a cross-sectional view showing the configuration of the image forming apparatus 1. The image forming apparatus 1 of this embodiment is a monochrome laser beam printer that forms an image on a recording material P based on image information input from an external device (not shown) such as a personal computer. Examples of the recording material P on which the image is formed include sheet materials made of various materials such as paper such as plain paper and cardboard, plastic film such as a sheet for an overhead projector, and cloth.

[0012] 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, width direction) of the photosensitive drum 11 (see FIG. 2) 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.

[0013] As shown in FIG. 1, the image forming apparatus 1 is equipped with a cassette 4 that stores recording materials P, and a discharge tray 14 on which the discharged recording materials P are stacked. The cassette 4 is arranged so that it can be pulled out in the Y direction, allowing the user to replenish the cassette 4 with recording materials P. After an image is formed on the recording material P conveyed from the cassette 4, it is discharged from a discharge outlet 15 in the discharge direction (Y direction) and stacked on the discharge tray 14. The discharge outlet 15 through which the recording material P passes before being discharged to the discharge tray 14 is formed on the top surface of a support frame 78 (see FIG. 3), which will be described later. In other words, the image forming apparatus 1 of this embodiment is a top-discharge type device.

[0014] The image forming apparatus 1 has a support frame 78, to which are attached a front cover 70, a rear cover 701, and an exterior cover 71 that is disposed on the side and top surface of the image forming apparatus 1 and that, together with the front cover 70 and rear cover 701, constitutes the exterior of the image forming apparatus 1. The front cover 70 is provided on a part of the end surface on the front side of the image forming apparatus 1, and covers a circuit board 100, which will be described later.

[0015] 2, the image forming apparatus 1 includes an image forming section 20 (image forming unit) that forms a toner image on a recording material P, a feeding section 30 that feeds the recording material P, a fixing section 9 that fixes the toner image formed by the image forming section 20 onto the recording material P, and a pair of discharge rollers 10. The image forming section 20, the feeding section 30, the fixing section 9, and the pair of discharge rollers 10 are housed in a support frame 78.

[0016] The image forming section 20 has an exposure unit 50, an electrophotographic process unit 40, and a transfer unit 7 including a transfer roller 7a that transfers a toner image carried on a photosensitive drum 11 of the process unit 40 onto a recording material P. The process unit 40 has the photosensitive drum 11, a cleaning unit 13, a charging roller 17, a developing roller 12, and a developing container 18 that contains toner.

[0017] The photosensitive drum 11 is a cylindrically shaped photosensitive member that functions as an image carrier for carrying an electrostatic latent image and a toner image. The photosensitive drum 11 of this embodiment has a photosensitive layer formed of a negatively chargeable organic photosensitive material on a drum-shaped substrate made of aluminum. The photosensitive drum 11 is driven to rotate in a predetermined direction (the direction of arrow R) at a predetermined process speed by a motor (not shown).

[0018] The charging roller 17 contacts the photosensitive drum 11 with a predetermined pressure, and a predetermined charging voltage is applied to the charging roller 17 by a charging power source (not shown), thereby uniformly charging the surface of the photosensitive drum 11 to a predetermined potential.

[0019] The exposure unit 50 scans and exposes the surface of the photosensitive drum 11 by irradiating the photosensitive drum 11 with laser light corresponding to image information input from an external device. This exposure forms an electrostatic latent image corresponding to the image information on the surface of the photosensitive drum 11.

[0020] The developing roller 12 is rotatably supported in a developing container 18. A developer containing toner and a carrier is stored in the developing container 18. The developing roller 12 is disposed at the opening of the developing container 18 so as to face the photosensitive drum 11.

[0021] The process unit 40 uses a contact development method. That is, the toner carried by the development roller 12 comes into contact with the photosensitive drum 11 in a development section (development area) where the photosensitive drum 11 and the development roller 12 face each other. A development voltage is applied to the development roller 12 by a development power supply (not shown). Under the development voltage, the toner carried by the development roller 12 is transferred from the development roller 12 to the drum surface in accordance with the potential distribution on the surface of the photosensitive drum 11, thereby developing the electrostatic latent image into a toner image.

[0022] The fixing unit 9 fixes the image by heating and melting the toner on the recording material and applying pressure to it. The fixing unit 9 has a heating roller 9a incorporating a fixing heater 9c, and a pressure roller 9b that is in pressure contact with the heating roller 9a.

[0023] Next, we will explain the image forming operation of the image forming apparatus 1. When an image formation command is input to the image forming apparatus 1, the image forming unit 20 starts an image forming process based on image information input from an external device (not shown) connected to the image forming apparatus 1.

[0024] The exposure unit 50 irradiates the photosensitive drum 11 with laser light based on input image information. Although not shown, the exposure unit 50 includes a laser oscillator that outputs laser light, a polygon mirror and lens for irradiating the photosensitive drum 11 with the laser light, a scanner motor that rotates the polygon mirror, a housing that houses and integrally supports these components, and the like. The exposure unit 50 is configured as a unit housed in a roughly rectangular parallelepiped housing, and is also called an optical box.

[0025] The photosensitive drum 11 is charged by the charging roller 17, and is irradiated with laser light by the exposure unit 50, thereby forming an electrostatic latent image on the surface of the photosensitive drum 11. Thereafter, the electrostatic latent image is developed by the developing roller 12, which rotates while carrying a toner image, and a toner image is formed on the photosensitive drum 11.

[0026] The feeding section 30 has a cassette 4 on which recording materials P are stacked, a pickup roller 3, a feeding roller 5a, and a separation roller 5b. In parallel with the image forming process described above, the pickup roller 3 feeds the recording materials P supported by the cassette 4. The recording materials P fed by the pickup roller 3 are separated into individual sheets by the feeding roller 5a and the separation roller 5b and conveyed to a conveying roller pair 5c. The recording materials P are then conveyed by the conveying roller pair 5c toward a transfer nip N1 formed by a transfer roller 7a and a photosensitive drum 11.

[0027] A transfer voltage is applied to the transfer roller 7a from a transfer power supply (not shown), and the toner image carried on the photosensitive drum 11 is transferred to the recording material P being conveyed by the conveying roller pair 5c. The recording material P with the transferred toner image is conveyed to the fixing unit 9, and the toner image is heated and pressurized as it passes through the fixing nip N2 between the heating roller 9a and pressure roller 9b of the fixing unit 9. This melts the toner and then fixes it, thereby fixing the toner image to the recording material P. After passing through the fixing unit 9, the recording material P is discharged outside the apparatus from the discharge port 15 in the discharge direction (Y direction) by the discharge roller pair 10, and is stacked on the discharge tray 14.

[0028] When forming images 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 by the pair of double-sided conveying rollers 5d via the conveying path 19 toward the transfer roller 7a. After an image is formed on the second side of the recording material P by the transfer roller 7a, the recording material P is discharged outside the apparatus by the pair of discharge rollers 10. After the toner image is transferred onto the recording material P, any toner remaining on the photosensitive drum 11 is cleaned by the cleaning unit 13.

[0029] As shown in FIG. 2 , the image forming apparatus 1 also includes a circuit board 100. The circuit board 100 includes a wiring board 101 (printed circuit board) made of an insulating material, and one side of the wiring board 101 is equipped with, for example, soldered electrical components 111 and 121. Conductor wiring is provided on and inside the wiring board 101, and a large number of electrical components 111 and 121 are electrically connected to the wiring board 101. The circuit board 100 has functions such as converting AC current supplied to the image forming apparatus 1 from an external power source to DC current and converting voltage to obtain a predetermined voltage value required for the image formation process. The circuit board 100 is disposed in the gap formed between the front cover 70 and the exposure unit 50 in the ejection direction, and the surface of the wiring board 101 on which the electrical components 111 and 121 are mounted faces the inside of the support frame 78.

[0030] <Support frame> Next, the support frame 78 will be described. As shown in FIG. 3, the support frame 78 has a pair of metal plate frames, a left frame 73 and a right frame 74, which face each other in approximately parallel relation, and multiple metal plate stays 75, 76, and 77. The left frame 73 and the right frame 74 are arranged on both end sides of the photosensitive drum 11 in the width direction (a first end side and a second end side opposite to the first end side in the rotational axis direction of the photosensitive drum 11). The left frame 73 and the right frame 74 are supported by metal plate stays 75, 76, and 77, which are highly rigid metal plate members, spanning them. The metal plate stay 75 is an example of a frame member, and in particular an example of a third metal plate (metal plate frame, bridging frame) that extends in the rotational axis direction (X direction) of the photosensitive drum 11 and connects the right frame 74 (first metal plate) and the left frame 73 (second metal plate). In addition, the left side plate frame 73 and the right side plate frame 74 are provided with reinforcing members, left side plate pillar 73a and right side plate pillar 74a (see Figures 4(a) and 5(a)), which extend from below to above, thereby increasing the rigidity of the support frame body 78.

[0031] A left floor frame 79 and a right floor frame 80 made of resin are disposed below the support frame 78, and these left floor frame 79 and right floor frame 80 contact the floor surface to support the support frame 78. Specifically, as shown in FIG. 4(a), the left side plate frame 73 is supported by contact at least two locations, contact portion 79a and contact portion 79b of the left floor frame 79. The contact portion 79a contacts the left side plate frame 73 on the front side of the left side plate frame 73 relative to the center in the Y direction, so that it contacts the curved surface of the left side plate frame 73, as an emphasis on rigidity of the left side plate frame 73. On the other hand, the contact portion 79b contacts the abutment surface of the left side plate frame 73, as shown in FIG. 4(b), as it is located near units related to conveyance, such as the conveyance roller pair 5c and the transfer roller 7a (see FIG. 2). The contact portion 79b contacts the left side plate frame 73 on the rear side of the left side plate frame 73 relative to the center in the Y direction.

[0032] Similarly, as shown in Fig. 5(a), the right side plate frame 74 is supported by contact at least two locations, contact portion 80a and contact portion 80b, of the right floor frame 80. The contact portion 80a is in contact with the bent surface of the right side plate frame 74, with emphasis on the rigidity of the right side plate frame 74, and is in contact with the right side plate frame 74 on the front side of the center in the Y direction. On the other hand, as shown in Fig. 5(b), the contact portion 80b is in contact with the abutment surface of the right side plate frame 74, with emphasis on accuracy, and is in contact with the right side plate frame 74 on the rear side of the center in the Y direction.

[0033] <Positioning configuration> Next, the positioning configuration of the exposure unit 50 in the support frame 78 will be described using Figures 6 to 15 while also referring to Figures 2 and 3. Figure 6 is a perspective view showing the exposure unit 50, the mounting attachment 84, the exposure unit support members (83A, 83B, 83C), and the sheet metal stay 75. However, in Figure 6, to make the description easier to understand, the exposure unit 50, the mounting attachment 84, the first support member 83A, and the second support member 83B are rotated about the X axis from their actual mounting positions on the sheet metal stay 75.

[0034] In this embodiment, the exposure unit 50 is attached to the sheet metal stay 75 while being attached to an attachment attachment 84. The attachment attachment 84, which serves as a positioning member, is an intermediate member made of resin, and as shown in FIG. 6, the exposure unit 50 can be attached to one side of the attachment attachment 84, and the attachment attachment 84 can be attached to the sheet metal stay 75 on the other side. When attached to the sheet metal stay 75, the attachment attachment 84 positions the exposure unit 50 at an angle with respect to a surface 751 of the sheet metal stay 75 so that light can be irradiated at a predetermined angle with respect to the surface of the photosensitive drum 11 (see FIG. 2). In other words, when the exposure unit 50 is assembled to the image forming apparatus, the orientation of the exposure unit 50 when viewed in the direction of the rotation axis of the photosensitive drum 11 (X direction) is set so that the direction of irradiation of exposure light onto the photosensitive drum 11 forms a predetermined angle with respect to the surface 751 of the sheet metal stay 75. In this embodiment, the surface 751 of the sheet metal stay 75 is a support surface that comes into contact with at least one of the exposure support members (83A, 83B) and the mounting attachment 84 and supports the exposure support members (83A, 83B, 83C) and the mounting attachment 84. That is, the surface 751 of the sheet metal stay 75 comes into contact with and supports the first support member 83A, the second support member 83B, the mounting attachment 84, etc. of the sheet metal stay 75. In addition, holes such as insertion holes 75b1 and 75b2, first mounting holes 75c1 and 75c2, and screw holes 75d1, 75d2, 75e1, and 75e2, which will be described later, are formed on the surface 751 of the sheet metal stay 75.

[0035] Furthermore, when the mounting attachment 84 is attached to the sheet metal stay 75, the exposure unit 50 is supported by a first support member 83A, a second support member 83B, and a third support member 83C provided on the sheet metal stay 75. These exposure support members (83A, 83B, 83C) are formed of a metal or the like that is more rigid than the mounting attachment 84, and support the exposure unit 50 attached to the mounting attachment 84 when the mounting attachment 84 is attached to the sheet metal stay 75. The exposure support members (83A, 83B, 83C) form a support plane as an imaginary plane on which the exposure unit 50 is supported at three points, and this support plane is inclined with respect to the surface 751 of the sheet metal stay 75. In other words, the support portions of the first support member 83A, the second support member 83B, and the third support member 83C that support the exposure unit 50 respectively define a support plane that is inclined at a predetermined angle with respect to the surface 751 of the sheet metal stay 75. A mounting attachment 84 is provided to determine the position of the exposure unit 50 on this support plane, and the exposure unit 50 is also supported by the mounting attachment 84 .

[0036] In this embodiment, the first support member 83A and the second support member 83B are formed separately from the mounting attachment 84 and can be attached to the sheet metal stay 75. In contrast, the third support member 83C is formed integrally with the sheet metal stay 75. The third support member 83C is formed, for example, by making a cut in a part of the surface 751 of the sheet metal stay 75 and bending it in the Z direction.

[0037] <Exposure unit> Figure 7 is a perspective view showing the exposure unit 50 as seen from the mounting attachment 84 side. As shown in Figure 7, the exposure unit 50 has a first support receiving portion 50a1, a second support receiving portion 50a2, and a third support receiving portion 50a3 on the mounting attachment 84 side. The first support receiving portion 50a1, the second support receiving portion 50a2, and the third support receiving portion 50a3 are support receiving portions or contacted portions that come into contact with and are supported by the first support member 83A, the second support member 83B, and the third support member 83C described above.

[0038] The first support receiving portion 50a1 and the second support receiving portion 50a2 are provided upstream of the center in the irradiation direction (negative Y direction) of light irradiated from the exposure unit 50 to the photosensitive drum 11 and are spaced apart from each other in the width direction. In contrast, the third support receiving portion 50a3 is provided downstream of the center in the irradiation direction of light and between the first support receiving portion 50a1 and the second support receiving portion 50a2 in the width direction.

[0039] Furthermore, the exposure unit 50 has a plurality of first bosses 50b1, 50b2 on the mounting attachment 84 side that fit with the mounting attachment 84. The first bosses 50b1, 50b2 are provided downstream of the center in the light irradiation direction and at positions spaced apart from each other on both ends of the widthwise direction that sandwich the third support receiving portion 50a3.

[0040] <Mounting attachment> 8 is a perspective view showing the mounting attachment 84 as seen from the exposure unit 50 side. The mounting attachment 84 has second mounting holes 84b1 and 84b2 on the exposure unit 50 side (one side). The second mounting holes 84b1 and 84b2 are provided downstream of the center in the light irradiation direction and at positions spaced apart from both ends in the width direction so that they can fit into the first boss portions 50b1 and 50b2 of the exposure unit 50. In this embodiment, the second mounting hole 84b2 on the right side in the X direction does not restrict the first boss portion 50b2, but the second mounting hole 84b1 on the left side determines the position of the exposure unit 50, and the second mounting hole 84b2 on the right side restricts the rotation of the exposure unit 50.

[0041] Furthermore, the mounting attachment 84 has second boss portions 84c1, 84c2, which are, for example, cross-shaped bosses, on the sheet metal stay 75 side (two-face side) in order to determine the position of the mounting attachment 84 relative to the sheet metal stay 75. The orientation of the shaft portions of the second boss portions 84c1, 84c2 formed on these two-face sides is different from the orientation of the second mounting holes 84b1, 84b2 formed on the one-face side described above.

[0042] For example, the shafts of the second bosses 84c1 and 84c2 on the two surfaces are formed in a first direction perpendicular to the surface 751 of the sheet metal stay 75 to which the mounting attachment 84 is attached. In contrast, the second mounting holes 84b1 and 84b on the one surface are formed in a second direction different from the first direction. In this embodiment, the second mounting holes 84b1 and 84b2 are formed in an inclined shape, as shown by the dotted lines in FIG. 8 , so that the entrances of the second mounting holes 84b1 and 84b2 are located downstream in the Y direction relative to the innermost portion. Because of the high degree of freedom in shape, which is an advantage of plastic parts over metal parts, the mounting attachment 84 can easily have the second mounting holes 84b1 and 84b2 and the second bosses 84c1 and 84c2 on the one and second surfaces, respectively, oriented in different directions, as described above.

[0043] <Exposure support member> FIG. 9 is a perspective view showing the first support member 83A. The second support member 83B may have a similar configuration to the first support member 83A, and therefore will not be illustrated or described here. As shown in FIG. 9, the first support member 83A has a support portion 831 that supports the exposure unit 50. The first support member 83A also has an insertion portion 83b for determining its position relative to the sheet metal stay 75 and abutting portions 83c1 and 83c2 that abut against the sheet metal stay 75. The first support member 83A also has a fixing portion 83c3 for fixing to the sheet metal stay 75. In this embodiment, the support portions 831 of the first support members 83A and 83B, which have the same shape, are fixed to the sheet metal stay 75 with screws (or bolts) or the like so that they are parallel to the left plate frame 73 and the right plate frame 74. To this end, the thin-plate fixing portion 83c3 has a screw hole 83c4 for inserting a screw or the like.

[0044] 6, first mounting holes 75c1 and 75c2, insertion holes 75b1 and 75b2, and screw holes 75d1, 75d2, 75e1, and 75e2 are formed on a surface 751 of the sheet metal stay 75. The first mounting holes 75c1 and 75c2 are provided for fitting with second boss portions 84c1 and 84c2 of the mounting attachment 84, and the insertion holes 75b1 and 75b2 are provided for inserting the insertion portions 83b of the first support member 83A and the second support member 83B.

[0045] The exposure unit 50 is attached to one surface of the mounting attachment 84 by fitting the first boss portions 50b1, 50b2 into second mounting holes 84b1, 84b2 (see FIG. 8) of the mounting attachment 84. The mounting attachment 84 is attached to the sheet metal stay 75 by fitting the second boss portions 84c1, 84c2 provided on the second surface opposite to the one surface into the first mounting holes 75c1, 75c2 of the sheet metal stay 75.

[0046] The insertion portions 83b of the first support member 83A and the second support member 83B are inserted into the insertion holes 75b1 and 75b2 of the sheet metal stay 75, and the abutment portions 83c1 and 83c2 (see FIG. 9) abut against the sheet metal stay 75. The fixing portion 83c3 comes into contact with the surface 751 of the sheet metal stay 75, and a screw is passed through the screw hole 83c4 of the fixing portion 83c3 and fastened in the screw fastening holes 75d1 and 75d2 of the sheet metal stay 75. In this way, the first support member 83A and the second support member 83B are fixed to the sheet metal stay 75.

[0047] A portion of the mounting attachment 84 rides on the fixing portions 83c of the first support member 83A and the second support member 83B. A second boss portion 84c1 of the mounting attachment 84 passes through a hole 83c5 formed in the fixing portion 83c of the first support member 83A and is fitted into a first mounting hole 75c1 of the sheet metal stay 75. A second boss portion 84c2 of the mounting attachment 84 passes through a hole 83c5 formed in the fixing portion 83c of the second support member 83B and is fitted into a first mounting hole 75c2 of the sheet metal stay 75. Furthermore, the mounting attachment 84 is formed with screw holes 84e1 and 84e2 for passing screws or the like. The screws passed through the screw holes 84e1 and 84e2 further pass through holes 83c6 formed in the fixing portions 83c of the first support member 83A and the second support member 83B, and are fastened to the screw fastening holes 75e1 and 75e2 of the sheet metal stay 75. In this way, the mounting attachment 84 is fixed to the sheet metal stay 75.

[0048] In this way, the first support member 83A and the second support member 83B (more specifically, the fixing portion 83c3) are sandwiched between the mounting attachment 84 and the sheet metal stay 75 and are fixed to the sheet metal stay 75 together with the mounting attachment 84 by screws. As a result, the exposure unit 50 attached to the mounting attachment 84 is positioned in an inclined state with respect to the surface 751 of the sheet metal stay 75 so that the irradiation angle of the laser light from the exposure unit 50 to the photosensitive drum 11 is a predetermined angle.

[0049] With the mounting attachment 84 fixed to the sheet metal stay 75, the exposure unit 50 is supported by the support portions 831 of the first support member 83A and the second support member 83B via the first support receiving portion 50a1 and the second support receiving portion 50a2, respectively. In addition, the third support receiving portion 50a3 is supported by the third support member 83C. In this way, all three support points of the exposure unit 50 are supported by the metal exposure support members (83A, 83B, 83C) which have higher rigidity than the resin mounting attachment 84, thereby making it possible to suppress vibration of the exposure unit 50.

[0050] That is, if the exposure unit 50 were supported only by the mounting attachment 84 made of resin, vibrations from a motor or the like provided inside the support frame 78 would be transmitted to the exposure unit 50, causing the laser light to blur and potentially resulting in poor images. Therefore, in this embodiment, in order to provide support that makes the exposure unit 50 less susceptible to vibration, exposure support members (83A, 83B, 83C) made of highly rigid metal are used. On the other hand, the mounting attachment 84 is made of resin because resin has a higher degree of freedom in shape than metal, making it easier to form the attachment into a shape that allows the exposure unit 50 to be mounted at different angles and that avoids the support portions 831 of the exposure support members (83A, 83B).

[0051] The exposure unit 50 is supported by exposure support members (83A, 83B, 83C) and is biased by first and second wire springs 81 and 82 as biasing means, as shown in Fig. 10. One first wire spring 81 is provided at each of the left and right positions on the front side, and one second wire spring 82 is provided on the rear side, and each biases the exposure unit 50 toward the sheet metal stay 75.

[0052] 11(a) and 11(b) show the first sheave spring 81. Here, the first sheave spring 81 that biases the right side of the exposure unit 50 will be described as an example. That is, in this embodiment, another first sheave spring 81 that biases the left side of the exposure unit 50 is provided, but since the left and right sides have the same configuration, the first sheave spring 81 that biases the right side will be shown as an example here.

[0053] 11(a) and 11(b), one end of the first wire spring 81 is connected to a wire spring holding member 85 that is sandwiched and held between a first support member 83A and a second support member 83B (see FIG. 6). A locking portion 81a is provided on the other end of the first wire spring 81, and the locking portion 81a is locked with a first support receiving portion 50a1 of the exposure unit 50, thereby biasing the exposure unit 50. Note that, as shown in FIG. 11(a), it is preferable that the wire spring holding member 85 be formed with an abutting portion 85a that abuts against the tip surface of the first support receiving portion 50a1 so that the locking portion 81a does not come off the first support receiving portion 50a1.

[0054] 12 shows the second wire spring 82. As shown in FIG. 12, one end of the second wire spring 82 is connected to a mounting hole 75d formed in the sheet metal stay 75. Meanwhile, the other end of the second wire spring 82 is detachably hooked onto a hook 75e formed on the sheet metal stay 75. When the other end of the second wire spring 82 is not hooked onto the hook 75e, the second wire spring 82 can swing with the mounting hole 75d side as a swing axis relative to the sheet metal stay 75. When the other end of the second wire spring 82 is hooked onto the hook 75e, the second wire spring 82 engages with the third support receiving portion 50a3 of the exposure unit 50, thereby biasing the exposure unit 50.

[0055] As described above, in this embodiment, the exposure unit 50 is biased by the first sheave spring 81 and the second sheave spring 82 at the support receiving portions (50a1-50a3) where it is supported by the exposure unit support members (83A, 83B, 83C). There are two reasons for biasing the exposure unit 50. The first reason is to stabilize the support of the exposure unit 50. The exposure unit 50 is only supported by the exposure unit support members (83A, 83B, 83C) and is not fixed to the exposure unit support members (83A, 83B, 83C) with screws, bolts, or the like. Therefore, without biasing, the support by the exposure unit support members (83A, 83B, 83C) would not be stable. Therefore, the exposure unit 50 is biased by the first wire spring 81 and the second wire spring 82 so that the contact portions (support receiving portions 50a1 to 50a3) of the exposure unit 50 do not move away from the exposure unit support members (83A, 83B, 83C). This makes it possible to stably support the exposure unit 50.

[0056] The second reason is to improve image quality. For example, if the image forming apparatus 1 is shaken by ambient vibrations during image formation, the biasing force prevents the vibrations from being transmitted to the exposure unit 50. Even if the exposure unit 50 does vibrate, the first sheave spring 81 and the second sheave spring 82 quickly damp the vibrations, thereby minimizing the impact on the image.

[0057] 13, the first support member 83A and the second support member 83B (specifically, the support portion 831) support the exposure unit 50 upstream of the upstream end 75a of the sheet metal stay 75 in relation to the direction of light irradiation from the exposure unit 50. In this way, as shown in FIG. 14, the exposure unit 50 is positioned such that the upstream end 501 of the exposure unit 50 is located upstream of the upstream ends 700 of the pair of left and right plate frames 73 and 74 in relation to the direction of light irradiation (opposite the Y direction) when viewed in the width direction.

[0058] By positioning the exposure unit 50 so that a portion of the exposure unit 50 protrudes forward beyond the left and right plate frames 73 and 74, as shown in FIG. 15 , space can be secured below the exposure unit 50, and this space can be utilized. That is, the first support member 83A and the second support member 83B are used not only to suppress vibration of the exposure unit 50 attached to the mounting attachment 84, but also to secure space below the exposure unit 50. In this embodiment, by arranging some of the electrical components 111 mounted on the circuit board 100 in the space secured below the exposure unit 50, the size of the main body on the front side of the image forming apparatus 1 can be reduced. Placing components that are larger in size in the Y direction, such as a low-voltage power transformer, a heat sink, and an electrolytic capacitor, in this space can reduce the overall size.

[0059] Furthermore, in this embodiment, since the mounting attachment 84 is formed from resin, its flexibility in shape can be utilized to form a heat-shielding wall 84d on the front side, as shown in FIG. 15 . The heat-shielding wall 84d is formed to block heat generated by the electrical components 111 mounted on the circuit board 100 from being transmitted to the exposure unit 50. The heat-shielding wall 84d extends approximately horizontally and is provided vertically between the exposure unit 50 and the electrical components 111. Because the temperature of the exposure unit 50 also rises due to self-heating, not receiving heat from other sources is a significant advantage in terms of heat control. Forming this heat-shielding wall 84d integrally with the mounting attachment 84, as shown in FIG. 8 , not only reduces the number of components but also makes it easier to form the heat-shielding wall 84d in an optimal shape and at an optimal position to match the layout of the circuit board 100.

[0060] In this embodiment, the shafts of the first bosses 50b1 and 50b2 of the exposure unit 50 and the first mounting holes 75c1 and 75c2 of the sheet metal stay 75 are oriented in the same direction (first direction). In other words, the first bosses 50b1 and 50b2 and the first mounting holes 75c1 and 75c2 are formed to be engageable with each other, and depending on the model of image forming apparatus, the exposure unit 50 can be attached directly to the sheet metal stay 75 without the attachment attachment 84.

[0061] As described above, in this embodiment, the exposure unit 50 is attached to the sheet metal stay 75 while attached to the mounting attachment 84, and the exposure unit 50 is supported by the exposure support members (83A, 83B, 83C) provided on the sheet metal stay 75. The mounting attachment 84 is made of resin, and the exposure support members (83A, 83B, 83C) are made of metal or other material that is more rigid than the mounting attachment 84. By attaching the exposure unit 50 to the mounting attachment 84, the exposure unit 50 is positioned at an angle with respect to the surface 751 of the sheet metal stay 75 so that the irradiation angle of the laser light from the exposure unit 50 to the photosensitive drum 11 is a predetermined angle. In other words, by changing the mounting attachment 84 to be attached, it is possible to change the positioning of the exposure unit 50 without changing the shape of the exposure unit 50. In such a case, by supporting the exposure unit 50 with highly rigid metal exposure support members (83A, 83B, 83C), it is possible to suppress vibration of the exposure unit 50 attached to the mounting attachment 84. In this way, in this embodiment, the exposure unit and sheet metal stays can be shared by many models without having to prepare multiple types of exposure units or sheet metal stays with different boss shaft directions or boss hole directions, thereby reducing costs.

[0062] As a comparative example to this embodiment, a configuration is conceivable in which a boss having an axis is formed on one of the exposure unit or the sheet metal stay, and a boss hole into which the boss can fit is formed on the other, in order to attach the exposure unit to a predetermined position on the sheet metal stay when assembling the image forming apparatus. These bosses and boss holes are formed so that the axis and the hole are oriented in the same direction, so that the irradiation angle of the laser light from the exposure unit to the photosensitive drum is a predetermined angle when the exposure unit is attached to the sheet metal stay.

[0063] In this comparative example, the exposure unit and the metal stay are mounted in an appropriate position so that the laser beam irradiation angle is a predetermined angle relative to the metal stay using bosses and boss holes pre-formed on the exposure unit and the metal stay. However, depending on the model of the image forming apparatus or manufacturing errors, the positions of the exposure unit and the photosensitive drum within the image forming apparatus body may differ. In such cases, in order to properly position the exposure unit, the comparative example requires the preparation of multiple types of exposure units and metal stays with different boss shaft directions or boss hole directions. In other words, the exposure unit and metal stay cannot be shared across multiple models, which increases costs.

[0064] According to this embodiment, as described above, the exposure unit and the metal plate stays can be shared by many different models, thereby reducing costs.

[0065] In the above-described embodiment, the second mounting holes 84b1 and 84b2 are provided on one side of the mounting attachment 84, and the second bosses 84c1 and 84c2 are provided on the other side (see FIG. 8 ). However, this is not limiting. For example, a boss may be provided on one side and a mounting hole on the other side. In this case, the exposure unit 50 would have a hole that fits into the boss provided on the one side, and the sheet metal stay 75 would have a boss that fits into the mounting hole provided on the other side. However, when fitting the boss to the exposure unit 50, the boss must be fitted so as to avoid the laser oscillator, polygon mirror, lens, scanner motor, and other components disposed within the exposure unit 50, which may result in an increase in the size of the exposure unit 50. Furthermore, providing a boss on the sheet metal stay 75 is more difficult than drilling a hole, and the boss may get in the way during assembly of the image forming apparatus 1, making assembly difficult. Therefore, as described above, it is preferable to provide a boss portion on the exposure unit 50, provide mounting holes on the sheet metal stay 75, and provide second mounting holes 84b1, 84b2 and second boss portions 84c1, 84c2 on the mounting attachment 84 so that they fit into these.

[0066] In this embodiment, by replacing the mounting attachment 84, it is possible to easily change the widthwise position of the exposure unit 50 relative to the sheet metal stay 75. That is, a number of mounting attachments 84 are prepared in which the positions of the second mounting holes 84b1, 84b2 on one side relative to the second boss portions 84c1, 84c2 on two sides in the widthwise direction are different, and the mounting attachment 84 selected when assembling the image forming apparatus 1 is used. In this way, it is possible to easily change the widthwise position of the exposure unit 50 relative to the sheet metal stay 75.

[0067] In the present embodiment, the first support member 83A, the second support member 83B, and the mounting attachment 84 each come into contact with the sheet metal stay 75 and are fixed to the sheet metal stay 75. However, the present invention is not limited to this. For example, the mounting attachment 84 may be fixed to the first support member 83A and the second support member 83B, and only the first support member 83A and the second support member 83B come into contact with the sheet metal stay 75 and are fixed to the sheet metal stay 75. Alternatively, the first support member 83A and the second support member 83B may be fixed to the mounting attachment 84, and only the mounting attachment 84 comes into contact with the sheet metal stay 75 and is fixed to the sheet metal stay 75. In the configuration of the present embodiment, the first support member 83A, the second support member 83B, and the mounting attachment 84 are each fixed to the sheet metal stay 75, and therefore, they can be positioned with high accuracy relative to the sheet metal stay 75 without being affected by the intersection of parts interposed between them. Therefore, although there is a certain degree of freedom in the configuration in which the first support member 83A, the second support member 83B, and the mounting attachment 84 are supported by the sheet metal stays 75, the configuration of this embodiment is desirable in order to take into account component tolerances and support the exposure unit 50 with greater precision.

[0068] Summary of the Disclosure The present disclosure includes at least the following configurations.

[0069] (Configuration 1) a rotating image carrier; a metal frame member having a support surface; an exposure unit that irradiates a surface of the image carrier with light to form an electrostatic latent image, the exposure unit being disposed such that the irradiation direction of the light onto the image carrier is inclined with respect to the support surface when viewed in the direction of the rotation axis of the image carrier; a metal support member that supports the exposure unit in an inclined position relative to the support surface; a resin positioning member that comes into contact with the exposure unit and positions the exposure unit; An image forming apparatus comprising: the support surface of the frame member contacts at least one of the support member and the positioning member; the exposure unit is attached to the frame member via the support member and the positioning member; An image forming apparatus characterized by:

[0070] (Configuration 2) the support member defines a support plane, which is an imaginary plane on which the exposure unit is supported; the positioning member contacts the exposure unit supported by the support member to determine the position of the exposure unit on the support plane; 2. The image forming apparatus according to claim 1,

[0071] (Configuration 3) the support member is a first support member, the image forming apparatus further includes a second support member and a third support member that support the exposure unit together with the first support member at positions different from each other when viewed in a vertical direction, the support plane is defined by support portions of the first support member, the second support member, and the third support member, each of which supports the exposure unit; 3. The image forming apparatus according to configuration 2.

[0072] (Configuration 4) the exposure unit has a contact portion that is contacted and supported by the support member, the image forming apparatus includes a biasing means for biasing the exposure unit so that the contacted portion does not move away from the support member attached to the frame member; 4. The image forming apparatus according to any one of configurations 1 to 3.

[0073] (Configuration 5) the exposure unit has a first boss portion on which a shaft portion is formed, the frame member has a first mounting hole formed in a first direction so as to be fittable with the first boss portion, the positioning member has, on one surface on which the exposure unit is attached, a second mounting hole formed in a second direction different from the first direction so as to be engageable with the first boss portion, and a second boss portion, on a second surface opposite to the one surface, having a shaft portion formed in the first direction so as to be engageable with the first mounting hole; 5. The image forming apparatus according to any one of configurations 1 to 4.

[0074] (Configuration 6) a support frame having a pair of side plates disposed on both end sides of the image carrier in a direction of a rotation axis of the image carrier and supporting the frame member; the support member is a first support member, a second support member provided opposite to the first support member at a position spaced apart from the first support member in the direction of the rotation axis, the second support member supporting the exposure unit attached to the positioning member; the first support member and the second support member support the exposure unit upstream of an upstream end of the frame member with respect to an irradiation direction of light irradiated from the exposure unit onto the image carrier. 6. The image forming apparatus according to any one of configurations 1 to 5.

[0075] (Configuration 7) a third support member that supports the exposure unit downstream of the first support member and the second support member in the irradiation direction; 7. The image forming apparatus according to configuration 6,

[0076] (Configuration 8) When viewed in the direction of the rotation axis, an upstream end of the exposure unit is located upstream of upstream ends of the pair of side plates in the irradiation direction. 8. The image forming apparatus according to configuration 6 or 7.

[0077] (Configuration 9) A circuit board having a plurality of electrical components mounted thereon is provided. the circuit board is arranged such that at least one of the plurality of electrical components is located upstream of upstream ends of the pair of side plates in the irradiation direction and below the exposure unit in the vertical direction, as viewed in the rotation axis direction. 9. The image forming apparatus according to configuration 8,

[0078] (Configuration 10) the positioning member has a shielding wall disposed so as to shield the exposure unit from the electrical component mounted below the exposure unit in the vertical direction; 10. The image forming apparatus according to configuration 9,

[0079] (Configuration 11) a first metal plate disposed on a first end side of the image carrier in a direction of a rotation axis of the image carrier; a second metal plate arranged on a second end side opposite to the first end side in the rotation axis direction, The frame member is a third metal plate extending in the rotation axis direction between the first metal plate and the second metal plate and connected to each of the first metal plate and the second metal plate. 11. The image forming apparatus according to any one of configurations 1 to 10. [Explanation of symbols]

[0080] 1...image forming apparatus, 11...image carrier (photosensitive drum), 50...exposure unit, 50a1...contact portion (first support receiving portion), 50a2...contact portion (second support receiving portion), 50a3...contact portion (third support receiving portion), 50b1 (50b2)...first boss portion, 73...side plate (left side plate frame), 74...side plate (right side plate frame), 75...frame member (sheet metal stay), 751...support surface (surface), 75c1 (75c2)...first mounting hole, 7 8...support frame body, 81...urging means (first wire spring), 82...urging means (second wire spring), 83A...support member (first support member), 83B...support member (second support member), 83C...support member (third support member), 84...positioning member (mounting attachment), 84b1 (84b2)...second mounting hole, 84c1 (84c2)...second boss portion, 84d...shielding wall (heat shielding wall), 100...circuit board, 111 (121)...electrical component, P...recording material

Claims

1. a rotating image carrier; a pair of side plates disposed on both end sides of the image carrier in a direction of a rotation axis of the image carrier; a metal frame member having a support surface and supported by the pair of side plates; an exposure unit that irradiates a surface of the image carrier with light to form an electrostatic latent image, the exposure unit being disposed such that the irradiation direction of the light onto the image carrier is inclined with respect to the support surface when viewed in the direction of the rotation axis, and including a first supported portion and a second supported portion; a first supporting member made of metal that abuts against the first supported portion and supports the exposure unit; a second support member made of metal that abuts against the second supported portion and supports the exposure unit, the second support member being provided at a position separated from the first support member in the rotation axis direction and facing the first support member; a resin positioning member that comes into contact with the exposure unit and positions the exposure unit; An image forming apparatus comprising: the first supported portion and the second supporting member are fixed to the frame member and support the exposure unit in an inclined position relative to the supporting surface; the support surface of the frame member contacts at least one of the first support member and the positioning member; the exposure unit is attached to the frame member via the first support member, the second support member, and the positioning member; An image forming apparatus characterized by:

2. A biasing means is provided for biasing the exposure unit so that the first supported portion does not separate from the first supporting member.

2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. the exposure unit has a first boss portion on which a shaft portion is formed, The frame member has a first mounting hole formed in a first direction, the positioning member has, on one surface on which the exposure unit is attached, a second mounting hole formed in a second direction different from the first direction so as to be engageable with the first boss portion, and a second boss portion, on a second surface opposite to the one surface, having a shaft portion formed in the first direction so as to be engageable with the first mounting hole; 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

4. The first support member and the second support member support the exposure unit upstream of the upstream end of the frame member in the irradiation direction.

3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

5. a third support member that supports the exposure unit downstream of the first support member and the second support member in the irradiation direction; 5. The image forming apparatus according to claim 4.

6. The third support member is integrally formed with the frame member.

6. The image forming apparatus according to claim 5,

7. When viewed in the direction of the rotation axis, an upstream end of the exposure unit is located upstream of upstream ends of the pair of side plates in the irradiation direction.

5. The image forming apparatus according to claim 4.

8. A circuit board having a plurality of electrical components mounted thereon is provided. the circuit board is arranged such that at least one of the plurality of electrical components is located upstream of upstream ends of the pair of side plates in the irradiation direction and below the exposure unit in the vertical direction, as viewed in the rotation axis direction.

8. The image forming apparatus according to claim 7,

9. the positioning member has a shielding wall disposed so as to shield the exposure unit from the electrical component mounted below the exposure unit in the vertical direction; 9. The image forming apparatus according to claim 8,

10. The pair of side plates includes a first metal plate arranged on a first end side of the image carrier in the direction of the rotation axis, and a second metal plate arranged on a second end side opposite the first end in the direction of the rotation axis, the frame member is a third metal plate extending in the rotation axis direction between the first metal plate and the second metal plate and connected to each of the first metal plate and the second metal plate; 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

Images