JP7479926B2 - Frame of image forming apparatus and image forming apparatus - Google Patents

Description

The present invention relates to a frame for an image forming device such as an electrophotographic copying machine or an electrophotographic printer (e.g., a laser beam printer, an LED printer, etc.).

Conventionally, a widely known configuration for the frame of an image forming apparatus includes support members such as side plates and pillars that support an image forming unit that forms an image, and a bottom plate to which the support members are fixed. The bottom plate is required to have high rigidity because it bears the entire weight of the image forming unit, the sheets on which images are formed, etc., via the support members.

In response to this, Patent Document 1 describes a configuration in which the bottom plate is made of two overlapping metal sheets, thereby increasing the rigidity of the bottom plate. In the configuration of Patent Document 1, one of the two metal sheets is provided with multiple frustum-shaped drawn portions formed by drawing, and the apexes of these drawn portions are connected to the other metal sheet, thereby further increasing the rigidity of the bottom plate.

JP 2002-16384 A

If bending or twisting occurs in the part of the bottom plate of the image forming device that supports the image forming unit, the relative positional accuracy between the components that make up the image forming unit may decrease, which may have a negative effect on image quality. In contrast, even if bending or twisting occurs in the part of the bottom plate that supports a component other than the image forming unit, such as the exterior cover, causing a decrease in positional accuracy, this does not have a direct effect on image formation, and therefore has little effect on image quality.

If the entire bottom plate is constructed by stacking two metal sheets together, as in the configuration of Patent Document 1, the weight of the bottom plate increases, and the weight of the entire frame also increases. Considering the transportability of the image forming device and the flexibility of the installation location, it is desirable to have a configuration that can reduce the weight of the entire frame while ensuring the rigidity of the part that supports the image forming unit and maintaining image quality.

In view of the current situation, the present invention aims to provide a frame for an image forming device that can reduce the weight of the entire frame while ensuring the rigidity of the portion of the bottom plate that supports the image forming unit.

A representative configuration of a frame of an image forming apparatus according to the present invention for achieving the above object includes a support member for supporting an image forming unit for forming an image on a sheet, and a bottom plate disposed vertically below the support member and to which the support member is fixed, the bottom plate being a first metal plate for supporting the support member, the first metal plate having a first base portion extending horizontally and a first bent portion formed by bending downward the entire circumference of an edge portion of the first base portion, and a second metal plate disposed vertically below the first metal plate, connected to the first metal plate, and supporting the support member together with the first metal plate. the second metal sheet extending horizontally and facing the first base, the second metal sheet being formed by bending the entire circumference of the edge of the second base upward and having a second bent portion in contact with the first bent portion, the second metal sheet being overlapped vertically on the first metal sheet so that a space is formed between the first base and the second base, and a third metal sheet being arranged adjacent to the first metal sheet and the second metal sheet in the horizontal direction and connected to at least one of the first metal sheet or the second metal sheet, and supporting an exterior cover of an image forming apparatus.

According to the present invention, it is possible to reduce the weight of the entire frame of the image forming device while ensuring the rigidity of the portion of the bottom plate that supports the image forming unit.

FIG. 1 is a schematic cross-sectional view of an image forming apparatus. FIG. 2 is a perspective view of a frame of the image forming apparatus. FIG. 2 is a perspective view of a frame of the image forming apparatus. FIG. 2 is an exploded perspective view of a frame of the image forming apparatus; FIG. 2 is a perspective view of a frame of the image forming apparatus. FIG. 2 is a perspective view of a frame of the image forming apparatus. FIG. FIG. FIG. 4 is an exploded perspective view of an upper member and a lower member of the bottom plate. FIG. 2 is a plan view of a frame of the image forming apparatus. FIG. 1 is a schematic cross-sectional view of an image forming apparatus.

<Image forming apparatus>
The overall configuration of the image forming apparatus according to the present invention will be described below together with the operation during image formation with reference to the drawings. Note that the dimensions, materials, shapes, relative positions, etc. of the components described below are not intended to limit the scope of the present invention unless otherwise specified.

The image forming apparatus A according to this embodiment is an intermediate tandem type image forming apparatus that transfers four colors of toner, yellow Y, magenta M, cyan C, and black K, to an intermediate transfer belt, and then transfers the image onto a sheet to form an image. In the following description, the components that use the above-mentioned toner colors are given the suffixes Y, M, C, and K, but the configuration and operation of each component are essentially the same except for the color of the toner used, so the suffixes will be omitted as appropriate unless a distinction is required.

Figure 1 is a schematic cross-sectional view of image forming apparatus A. As shown in Figure 1, image forming apparatus A includes an image forming unit 10 that forms an image on a sheet S, and a feeding unit 20 that feeds the sheet S toward the image forming unit 10.

The image forming unit 10 includes photosensitive drums 1 (1Y, 1M, 1C, 1K) as photosensitive members, charging rollers 2 (2Y, 2M, 2C, 2K), and developing devices 4 (4Y, 4M, 4C, 4K). The image forming unit 10 also includes primary transfer rollers 5 (5Y, 5M, 5C, 5K), a laser scanner unit 3, an intermediate transfer belt 6, a secondary transfer roller 7, and a secondary transfer opposing roller 8.

The feeding unit 20 includes sheet cassettes 11a to 11c in which sheets S are stored, and pick rollers 12a to 12c that pick up sheets S stored in the sheet cassettes 11a to 11c. It also includes feed rollers 13a to 13c that feed the sheets S picked up by the pick rollers 12a to 12c to a transport path, transport rollers 14a to 14d that transport the sheets S in the transport path, and a registration roller 15.

When forming an image using image forming device A, an image formation job signal is first input to a control unit (not shown). This causes sheet S stored in one of sheet cassettes 11a to 11c to be picked up by pick rollers 12a to 12c. Next, sheet S is sent to registration rollers 15 by feed rollers 13a to 13c and transport rollers 14a to 14d. After that, the sheet S is corrected for skew by registration rollers 15, and then sent to a secondary transfer section formed by secondary transfer roller 7 and secondary transfer opposing roller 8 at a predetermined timing.

Meanwhile, in the image forming unit 10, the surface of the photosensitive drum 1Y is first charged by the charging roller 2Y. Then, the laser scanner unit 3 irradiates the surface of the photosensitive drum 1Y with laser light according to image data sent from an external device (not shown), forming an electrostatic latent image on the surface of the photosensitive drum 1Y. Then, the developing device 4Y causes yellow toner to adhere to the electrostatic latent image formed on the surface of the photosensitive drum 1Y, forming a yellow toner image on the surface of the photosensitive drum 1Y. The toner image formed on the surface of the photosensitive drum 1Y is primarily transferred to the intermediate transfer belt 6 by applying a primary transfer bias to the primary transfer roller 5Y.

By a similar process, magenta, cyan and black toner images are formed on the photosensitive drums 1M, 1C and 1K. Then, by applying a primary transfer bias to the primary transfer rollers 5M, 5C and 5K, these toner images are transferred and superimposed on the yellow toner image on the intermediate transfer belt 6. As a result, a full-color toner image corresponding to the image signal is formed on the surface of the intermediate transfer belt 6. Note that the toner adhering to the photosensitive drums 1Y, 1M, 1C and 1K after the primary transfer is removed by a cleaning member (not shown) and collected in the collected toner container 18.

Then, as the intermediate transfer belt 6 rotates, the full-color toner image is sent to the secondary transfer section. Then, at the secondary transfer section, a secondary transfer bias is applied to the secondary transfer roller 7, so that the full-color toner image on the intermediate transfer belt 6 is transferred to the sheet S. The sheet S onto which the toner image has been transferred is transported by the transport roller 14e to the fixing device 9, where it is heated and pressurized, thereby fixing the toner image on the sheet S to the sheet S. The sheet S onto which the toner image has been fixed is then discharged by the discharge roller 17 onto the discharge tray 19.

<Frame of Image Forming Apparatus>
Next, the configuration of the frame 100 of the image forming apparatus A will be described.

2 is a perspective view of the frame 100 of the image forming apparatus A as seen from the front side. FIG. 3 is a perspective view of the frame 100 of the image forming apparatus A as seen from the rear side. FIG. 4 is an exploded perspective view of the frame 100 of the image forming apparatus A. As shown in FIGS. 2, 3, and 4, the frame 100 of the image forming apparatus A is configured by connecting an upper frame 50 and a lower frame 70. The upper frame 50 and the lower frame 70 are each made of sheet metal, and the upper frame 50 is disposed above the lower frame 70 in the vertical direction. The lower frame 70 is a standard mounting on the image forming apparatus A as the frame 100, and is different from the cassette pedestal unit that is optionally attached as an option for functional expansion such as increasing the number of sheets S that can be stored. The dashed line V shown in FIG. 1 indicates the boundary between the upper frame 50 and the lower frame 70.

The upper frame 50 is composed of a front plate 53, a rear plate 52, and stays 58, 59, 60, and 61 that connect the front plate 53 and the rear plate 52. The front plate 53 is composed of an upper right support column 54, an upper left support column 55, and stays 56 and 57 that connect the upper right support column 54 and the upper left support column 55. The stays 56 and 57 are welded to the upper right support column 54 and the upper left support column 55. The stay 58 is welded to the upper right support column 54 and the rear plate 52. The stay 59 is welded to the upper left support column 55 and the rear plate 52. The stays 60 and 61 are welded to the stay 56 and the rear plate 52.

The lower frame 70 is composed of a bottom plate 71, a front plate 73, a rear plate 72, and reinforcing plates 79a, 79b connected to the front plate 73, the rear plate 72, and the bottom plate 71. The front plate 73 is composed of a lower right support column 74, a lower left support column 75, and a stay 76 connecting the lower right support column 74 and the lower left support column 75. The lower right support column 74 is fixed to the upper right support column 54 of the upper frame 50 with a screw (not shown). The lower left support column 75 is fixed to the upper left support column 55 of the upper frame 50 with a screw (not shown). The stay 76 is welded to the lower right support column 74 and the lower left support column 75. The rear plate 72, the lower right support column 74, and the lower left support column 75 are fixed to the bottom plate 71 with screws (not shown).

As described below, the rear plate 52 has a support portion 52a that supports the photosensitive drum 1, a bent portion 52b where the end of the support portion 52a in the X direction is bent perpendicularly to the -Y direction, and a bent portion 52c where the end of the support portion 52a in the -X direction is bent perpendicularly to the -Y direction. The rear plate 72 has a support portion 72a that supports the sheet cassettes 11a to 11c, a bent portion 72b where the end of the support portion 72a in the X direction is bent perpendicularly to the -Y direction, and a bent portion 72c where the end of the support portion 72a in the -X direction is bent perpendicularly to the -Y direction. The support portion 52a of the rear plate 52 and the support portion 72a of the rear plate 72, the bent portion 52b of the rear plate 52 and the bent portion 72b of the rear plate 72, and the bent portion 52c of the rear plate 52 and the bent portion 72c of the rear plate 72 are each welded and connected.

Figure 5 is a diagram showing the state in which members supporting the photosensitive drum 1 and the sheet cassette 11 are attached to the frame 100 of the image forming apparatus A. As shown in Figure 5, a drum support member 81 supporting the photosensitive drum 1 and the developing device 4 is positioned and attached to the upper right support pillar 54 and the upper left support pillar 55 of the upper frame 50. The drum support member 81 rotatably supports one end in the rotational axis direction of the developing sleeve (not shown) provided on the photosensitive drum 1 and the developing device 4. The other end in the rotational axis direction of the photosensitive drum 1 and the developing sleeve is rotatably supported by the support portion 52a of the rear side plate 52.

A belt support member 82 that supports the intermediate transfer belt 6 is positioned and attached to the upper right support column 54 and upper left support column 55 of the upper frame 50. The belt support member 82 rotatably supports one end in the rotational axis direction of the secondary transfer opposing roller 8 and other rollers around which the intermediate transfer belt 6 is stretched. The other end in the rotational axis direction of the secondary transfer opposing roller 8 is rotatably supported by the support portion 52a of the rear side plate 52.

A front side plate, which is the front frame of the fixing transport unit 84 in which the fixing device 9 and transport roller 14e are unitized, is attached to the upper right support pillar 54 and upper left support pillar 55 of the upper frame 50. The position of the fixing transport unit 84 relative to the upper right support pillar 54 and upper left support pillar 55 is determined by fitting pins (not shown) of the front side plate of the fixing transport unit 84 into fitting holes 54a2c formed in the upper right support pillar 54 and fitting holes 55a formed in the upper left support pillar 55.

That is, the photosensitive drum 1, developing device 4, intermediate transfer belt 6, etc., which constitute part of the image forming unit 10, are supported by the rear side plate 52, upper right support pillar 54, and upper left support pillar 55 via the drum support member 81 and belt support member 82. The rear side plate 72, lower right support pillar 74, and lower left support pillar 75, which are connected vertically below the rear side plate 52, upper right support pillar 54, and upper left support pillar 55, receive the load of the photosensitive drum 1, developing device 4, and intermediate transfer belt 6, and indirectly support these members. That is, the drum support member 81, belt support member 82, the rear side plate 52, upper right support pillar 54, and upper left support pillar 55 of the upper frame 50, and the rear side plate 72, lower right support pillar 74, and lower left support pillar 75 of the lower frame 70 are each support members that support the image forming unit 10. The bottom plate 71 is also positioned vertically below the support member that supports the image forming unit 10, and a rear side plate 72, a lower right support column 74, and a lower left support column 75, which are part of the support member that supports the image forming unit 10, are fixed to the bottom plate 71.

The frame of the fixing transport unit 84 supports the transport roller 14d. That is, the position of the fixing transport unit 84 relative to the upper right support column 54 and the upper left support column 55 determines the position of the transport roller 14d. In addition, one end of the rotation axis direction of the transport roller 14a, which delivers the sheet S to the transport roller 14d, is positioned and rotatably supported by the lower right support column 74. The other end of the rotation axis direction of the transport roller 14a is rotatably supported by the support portion 52a of the rear side plate 52.

Support rails 83a supporting sheet cassette 11a, 83b supporting sheet cassette 11b, and 83c supporting sheet cassette 11c are positioned and attached to the lower right support pillar 74 and lower left support pillar 75 of the lower frame 70. The support rails 83a, 83b, and 83c are stays that connect the lower right support pillar 74 and lower left support pillar 75 to the rear plate 72. The sheet cassettes 11a to 11c slide while being guided by the support rails 83a to 83c, and are inserted in the -Y direction and pulled out in the Y direction. The inserted sheet cassettes 11a to 11c are supported by the support rails 83a to 83c and the support portion 72a of the rear plate 72.

In this embodiment, the front of image forming device A is located in the direction of arrow Y, which is the direction in which sheet cassettes 11a to 11c are pulled out, and the back of image forming device A is located in the direction of arrow -Y, which is the direction in which sheet cassettes 11a to 11c are inserted. The right side of image forming device A is located in the direction of arrow X, which is perpendicular to the directions of arrows Z and -Z, which are vertical to the directions of arrows Y and -Y, and the left side of image forming device A is located in the opposite direction, the direction of arrow -X. In other words, in the direction of movement of sheet cassettes 11a to 11c, the lower right support pillar 74 and lower left support pillar 75 of lower frame 70 and the rear plate 72 are arranged opposite each other. The lower right support pillar 74 and lower left support pillar 75 are also arranged opposite each other in a direction perpendicular to the direction of movement of sheet cassettes 11a to 11c and the vertical direction.

6 is a diagram showing the duct 41 and the power supply unit 42 attached to the frame 100 of the image forming apparatus A. As shown in FIG. 6, the duct 41, the power supply unit 42, and the exterior cover 43 on the rear side of the image forming apparatus A are attached to the extended bottom plate portion 71c that constitutes a part of the bottom plate 71 of the frame 100. The duct 41 has a fan (not shown) therein, and the air around the image forming unit 10 is discharged to the outside of the image forming apparatus A by the airflow generated by the fan, thereby suppressing the temperature rise of the image forming unit 10. The duct 41 may be configured to discharge the air around the fixing device 9 to the outside of the image forming apparatus A, thereby suppressing the temperature rise of the fixing device 9. The power supply unit 42 has a power supply board (not shown) that receives power from a commercial power source, generates power used in the image forming unit 10, and supplies power to the image forming unit 10. The lower end of the exterior cover 43 is fixed to the end face of the extended bottom plate portion 71c in the arrow -Y direction by a screw 99. The portion of the exterior cover 43 other than the lower end is fixed to the rear side plate 52 with screws. The exterior cover 43 on the rear side of the image forming device A may be formed as a single piece as in the configuration of this embodiment, or may be divided in the vertical direction.

<Bottom plate>
Next, the configuration of the bottom plate 71 will be described in detail.

Figure 7 is a view of the bottom plate 71 as seen from the direction of the arrow -Z. Figure 8 is a schematic cross-sectional view of the bottom plate 71 cut at the K-K cross section shown in Figure 7. Figure 9 is an exploded perspective view of the upper member 71a and lower member 71b of the bottom plate 71. As shown in Figures 7, 8, and 9, the bottom plate 71 is composed of three metal sheets: the upper member 71a (first metal sheet), the lower member 71b (second metal sheet), and the extended bottom plate portion 71c (third metal sheet). In this embodiment, the thickness of the upper member 71a is 1.2 mm, the thickness of the lower member 71b is 1.6 mm, and the thickness of the extended bottom plate portion 71c is 0.8 mm.

The rear plate 72, lower right support 74, and lower left support 75 are fixed to the upper member 71a with screws, and support the image forming unit 10 via these members. The lower member 71b is disposed vertically below the upper member 71a, is connected to the upper member 71a, and supports the image forming unit 10 together with the upper member 71a. Note that the method of connecting the rear plate 72, lower right support 74, and lower left support 75 to the upper member 71a is not limited to fixing with screws, and may be other methods such as welding. Also, the rear plate 72, lower right support 74, and lower left support 75 may be configured to be connected to the lower member 71b.

The upper member 71a has a base 71a1 (first base) that extends horizontally, and a bent portion 71a2 (first bent portion) that is formed by bending the entire circumference of the edge of the base 71a1 downward by edge drawing. The base 71b1 has a rectangular shape. The bent portion 71a2 is a surface that extends approximately perpendicular to the base 71a1.

The lower member 71b has a base 71b1 (second base) extending horizontally, and a bent portion 71b2 (second bent portion) formed by bending the entire circumference of the edge of the base 71b1 downward by edge-drawing. The base 71b1 is rectangular, and casters 90a to 90d used to move the image forming device A are attached to each of its four corners. The bent portion 71b2 is a surface that extends approximately perpendicular to the base 71b1.

The upper member 71a and the lower member 71b are stacked vertically to form a box shape. Specifically, the bent portion 71a2 of the upper member 71a and the bent portion 71b2 of the lower member 71b face each other in the direction of the arrow X or the direction of the arrow Y, are in contact with each other, and are welded at the welded portion 30 (FIG. 8). That is, each of the four sides forming the approximately rectangular shape of the base 71a1 of the upper member 71a and each of the four sides forming the approximately rectangular shape of the base 71b1 of the lower member 71b are connected at the bent portion 71a2 of the upper member 71a and the bent portion 71b2 of the lower member 71b. The welded portion 30 is provided at a constant interval over the entire area of the bent portions 71a2 and 71b2. The base 71a1 of the upper member 71a and the base 71b1 of the lower member 71b face each other in the direction of the arrow Z, and a space is formed between them.

By stacking the upper and lower members 71a and 71b that support the image forming unit 10 vertically to form a box shape in this manner, the rigidity of the portion of the bottom plate 71 that supports the image forming unit 10 can be increased. Therefore, even if the upper and lower members 71a and 71b bear the weight of the image forming unit 10 and the sheet S, the upper and lower members 71a and 71b are prevented from bending or twisting. This prevents the relative positional accuracy between the members that make up the image forming unit 10 from decreasing, and image quality can be maintained.

The base 71b1 of the lower member 71b is provided with a plurality of squeezing portions 71b1a (protrusions) that are deformed into a truncated cone shape by drawing. The squeezing portions 71b1a are formed to protrude vertically upward from the base 71b1 toward the space between the bases 71a1 and 71b1. The squeezing portions 71b1a are arranged so as to be approximately parallel to each of the four sides of the rectangle of the base 71b1 of the lower member 71b. The squeezing portions 71b1a are also arranged diagonally on the rectangle of the base 71b1 of the lower member 71b. The vertices 71b1a1 of the squeezing portions 71b1a contact the base 71a1 of the upper member 71a and are welded to the base 71a1 at the welded portion 31 (Figure 8).

In this way, the lower member 71b is provided with a drawing portion 71b1a, and the upper member 71a and the lower member 71b are connected at the drawing portion 71b1a. With this configuration, the section modulus of the portion of the bottom plate 71 that supports the image forming unit 10 is increased, and the rigidity of the portion of the bottom plate 71 that supports the image forming unit 10 can be further increased. The shape of the drawing portion 71b1a is not limited to a truncated cone shape, and may be another truncated cone shape. Furthermore, the rigidity of the lower member 71b can be increased if the drawing portion 71b1a is subjected to drawing even if it is not a truncated cone shape. Furthermore, a drawing portion that protrudes downward in the vertical direction and has a shape similar to that of the drawing portion 71b1a may be provided at the base 71a1 of the upper member 71a, and this drawing portion may be connected to the base 71b1 of the lower member 71b by welding or the like.

In this embodiment, the upper member 71a and the lower member 71b are connected by welding, but other methods such as crimping or screwing may be used. Also, in this embodiment, the upper member 71a is fitted onto the outside of the lower member 71b so as to cover the lower member 71b, but the relationship between the two may be reversed.

Figure 10 is a view of the frame 100 as viewed from the direction of the arrow X. Note that the reinforcing plates 79a and 79b are omitted in Figure 10. As shown in Figures 6 and 10, the extended bottom plate portion 71c is positioned closer to the rear side of the image forming device A than the upper member 71a and the lower member 71b. In other words, the extended bottom plate portion 71c is positioned adjacent to the upper member 71a and the lower member 71b in the horizontal direction. As described above, the extended bottom plate portion 71c supports the duct 41, the power supply unit 42, and the exterior cover 43 of the image forming device A.

The extended bottom plate portion 71c has a base portion 71c1 (third base portion) extending horizontally, and a bent portion 71c2 (third bent portion) formed by bending a part of the edge of the base portion 71c1 upward by edge drawing. A part of the bent portion 71c2 of the extended bottom plate portion 71c is further bent in the direction of the arrow Y so as to overlap with the base portion 71a1 of the upper member 71a to form a fixed portion 71c2a. The upper member 71a and the extended bottom plate portion 71c are connected by fixing with screws at the part where the fixed portion 71c2a of the extended bottom plate portion 71c and the base portion 71a1 of the upper member 71a overlap. The extended bottom plate portion 71c may be connected to the lower member 71b, or to both the upper member 71a and the lower member 71b. Furthermore, the base 71c1 of the extended bottom plate portion 71c does not have a cone-shaped frustum-shaped cone that protrudes vertically.

The portion where the fixed portion 71c2a of the extended bottom plate portion 71c and the base portion 71a1 of the upper member 71a overlap is located closer to the rear of the image forming device A than the support portion 72a of the rear plate 72. In other words, the connecting portion of the extended bottom plate portion 71c with the upper member 71a is located closer to the rear of the image forming device A than the support portion 72a of the rear plate 72. With this configuration, the support portion 72a of the rear plate 72 that supports the image forming unit 10 can be supported by the highly rigid upper member 71a and lower member 71b, rather than by the extended bottom plate portion 71c which is made up of a single layer.

A reinforcing plate 79a (connecting member) is connected to the end face of the bent portion 71c2 of the extended bottom plate portion 71c in the X direction. The reinforcing plate 79a is fixed with screws to the extended bottom plate portion 71c, upper member 71a, lower member 71b, lower right support 74, and rear plate 72. A reinforcing plate 79b (connecting member) is connected to the end face of the bent portion 71c2 of the extended bottom plate portion 71c in the -X direction. The reinforcing plate 79b is fixed with screws to the extended bottom plate portion 71c, upper member 71a, lower member 71b, lower left support 75, and rear plate 72. By connecting the extended bottom plate portion 71c to the upper member 71a and lower member 71b in this way with the reinforcing plates 79a and 79b, the rigidity of the extended bottom plate portion 71c can be increased. The reinforcing plates 79a and 79b only need to be fixed to at least the extended bottom plate portion 71c and at least one of the upper member 71a or the lower member 71b.

In this manner, in this embodiment, the portion of the bottom plate 71 that supports the image forming unit 10 is constructed by stacking two metal sheets, the upper member 71a and the lower member 71b, in a box shape. In addition, the portion of the bottom plate 71 that supports the duct 41, the power supply unit 42, and the exterior cover 43, i.e., the portion that supports the members other than the image forming unit 10, is constructed from a single piece of metal sheet, the extended bottom plate portion 71c. This ensures the rigidity of the portion that supports the image forming unit 10 and maintains image quality, while making it possible to reduce the overall weight of the frame 100 compared to a configuration in which the entire bottom plate 71 is made of two metal sheets stacked together, and also reduces material costs and manufacturing costs.

In the configuration of this embodiment, it is physically possible to extend either the upper member 71a or the lower member 71b to provide the function of the extended bottom plate portion 71c. In this case, however, welding cannot be performed between the end face of the bent portion 71a2 of the upper member 71a in the -Y direction and the end face of the bent portion 71b2 of the lower member 71b in the -Y direction, and the rigidity of the portion of the bottom plate 71 that supports the image forming unit 10 is reduced. Therefore, it is preferable to configure the upper member 71a, the lower member 71b, and the extended bottom plate portion 71c as independent metal plates.

The arrangement of the members supported by the upper frame 50 and the lower frame 70 can be changed as appropriate. For example, as shown in FIG. 11, the sheet cassette 11a supported by the lower frame 70 can be made smaller to store small-sized sheets S, and the collected toner container 18 can be placed in the space formed thereby.

1...Photosensitive drum (photoconductor)
10: Image forming unit 41: Duct 43: Exterior cover 71: Bottom plate 71a: Upper member (first metal plate)
71b...Lower member (second metal plate)
71b1a...throttled portion (protruding portion)
71c...extended bottom plate portion (third metal plate)
72...Rear plate (support member)
74...Lower right support (support member)
75...Lower left support (support member)
79a, 79b...reinforcing plates (connecting members)
90a to 90d: Casters 100: Frame A: Image forming apparatus

Claims (11)

a support member for supporting an image forming unit for forming an image;
a bottom plate disposed vertically below the support member and to which the support member is fixed;
Equipped with
The bottom plate is
A first metal plate supporting the support member, the first metal plate having a first base portion extending in a horizontal direction and a first bent portion formed by bending an entire periphery of an edge portion of the first base portion downward;
a second metal sheet arranged vertically below the first metal sheet, connected to the first metal sheet, and supporting the support member together with the first metal sheet, the second metal sheet extending horizontally and having a second base portion facing the first base portion, and a second bent portion formed by bending an entire periphery of an edge portion of the second base portion upward and contacting the first bent portion, the second metal sheet being overlapped vertically with the first metal sheet so that a space is formed between the first base portion and the second base portion;
a third metal plate that is disposed adjacent to the first metal plate and the second metal plate in the horizontal direction and is connected to at least one of the first metal plate and the second metal plate, and supports an exterior cover of an image forming apparatus;
A frame body of an image forming apparatus comprising: The frame of the image forming apparatus according to claim 1, characterized in that the first bent portion of the first metal plate and the second bent portion of the second metal plate are connected. 3. The frame of the image forming apparatus according to claim 1, wherein at least one of the first base portion and the second base portion has a drawn portion formed by drawing. The image forming frame according to claim 3, characterized in that the diaphragm portion is a plurality of protrusions deformed into a frustum shape so as to protrude vertically toward the space, and the first base and the second base are connected at the apex of each of the plurality of protrusions. The frame of the image forming device according to any one of claims 1 to 4, characterized in that the third metal plate has a third base portion extending in the horizontal direction and a third bent portion formed by bending an edge of the third base portion, and the third base portion does not have a cone portion deformed into a frustum shape so as to protrude in the vertical direction. The third metal plate has a third base portion extending in a horizontal direction and a third bent portion formed by bending an edge of the third base portion,
A frame body of an image forming apparatus as described in any one of claims 1 to 5, characterized in that it is provided with a connecting member that connects the third bent portion of the third sheet metal to at least one of the first bent portion of the first sheet metal or the second bent portion of the second sheet metal. The frame of an image forming device according to any one of claims 1 to 6, characterized in that casters are attached to the second metal plate. 8. The frame of the image forming apparatus according to claim 1, wherein the third metal plate supports a duct for discharging air around the image forming unit to the outside of the image forming apparatus. The frame of an image forming apparatus according to any one of claims 1 to 8, characterized in that the third metal plate supports a power supply board that supplies power to the image forming unit. The image forming unit has a photoconductor,
10. The frame of the image forming apparatus according to claim 1, wherein the support member includes a side plate that rotatably supports the photoconductor. A frame of the image forming apparatus according to any one of claims 1 to 10,
an image forming unit supported by the frame and configured to form an image on a sheet;
An image forming apparatus comprising:

Images