阅读说明：本技术 图像形成装置的框架和图像形成装置 (Frame of image forming apparatus and image forming apparatus ) 是由 松村拓也 于 2021-05-12 设计创作，主要内容包括：一种图像形成装置的框架,包括：第一框架；第二框架,其设置在第一框架上方,第二框架联接到第一框架；和联接构件,其联接第一支柱和第二支柱,第一支柱是第一框架的一部分,第一支柱包括：第一基部部分；第一板部分；和第二板部分,第二支柱是第二框架的一部分,第二支柱包括：第二基部部分,其设置在第一基部部分上方,第二基部部分与第一基部部分接触；第三板部分；和第四板部分,联接构件包括：与第一基部部分及第二基部部分相对并间隔开的第三基部部分；第五板部分；和第六板部分。(A frame of an image forming apparatus, comprising: a first frame; a second frame disposed above the first frame, the second frame being coupled to the first frame; and a coupling member that couples the first pillar and the second pillar, the first pillar being a part of the first frame, the first pillar including: a first base portion; a first plate portion; and a second plate portion, the second pillar being a part of the second frame, the second pillar including: a second base portion disposed above the first base portion, the second base portion in contact with the first base portion; a third plate portion; and a fourth plate portion, the coupling member including: a third base portion opposite and spaced apart from the first and second base portions; a fifth plate portion; and a sixth plate portion.)

1. A frame of an image forming apparatus, comprising:

a first frame configured to support: a sheet cassette configured to accommodate sheets; and a first conveyance roller configured to convey a sheet extracted from a sheet cassette;

a second frame disposed in a vertical direction above the first frame, the second frame coupled to the first frame, the second frame configured to support: a second conveyance roller configured to receive the sheet conveyed by the first conveyance roller and convey the sheet; and an image forming unit configured to form an image on the sheet conveyed by the second conveying roller; and

a first strut configured to be part of a first frame, the first strut comprising: a first base portion; a first plate portion extending substantially perpendicularly from the first base portion; and a second plate portion extending substantially perpendicularly from the first base portion, the second plate portion being opposite the first plate portion;

a second strut configured to be part of a second frame, the second strut comprising: a second base portion disposed vertically above the first base portion, the second base portion being in contact with the first base portion; a third plate portion extending substantially perpendicularly from the second base portion, the third plate portion being disposed vertically above the first plate portion; and a fourth plate portion extending substantially perpendicularly from the second base portion, the fourth plate portion being opposite the third plate portion, the fourth plate portion being disposed vertically above the second plate portion,

a coupling member coupling the first strut and the second strut, the coupling member comprising: a third base portion opposite and spaced apart from the first and second base portions; a fifth plate portion extending substantially perpendicularly from the third base portion, the fifth plate portion coupled to the first plate portion and the third plate portion; and a sixth plate portion extending substantially perpendicularly from the third base portion, the sixth plate portion being opposite the fifth plate portion, the sixth plate portion being coupled to the second plate portion and the fourth plate portion.

2. The frame of an image forming apparatus according to claim 1, wherein

The first pillar includes a reinforcement member that reinforces the first pillar, the reinforcement member being disposed below the coupling member in the vertical direction, the reinforcement member including: a fourth base portion; a seventh plate portion extending substantially perpendicularly from the fourth base portion; and an eighth plate portion extending substantially perpendicularly from the fourth base portion, the eighth plate portion being opposite the seventh plate portion,

the fourth base portion of the stiffening member is opposite and spaced apart from the first base portion of the first strut,

the seventh plate portion of the reinforcement member is coupled to the first plate portion of the first strut, an

The eighth plate portion of the reinforcement member is coupled to the second plate portion of the first strut.

3. The frame of an image forming apparatus according to claim 1, wherein

The second pillar includes a reinforcement member that reinforces the second pillar, the reinforcement member being disposed above the coupling member in the vertical direction, the reinforcement member including: a fourth base portion; a seventh plate portion extending substantially perpendicularly from the fourth base portion; and an eighth plate portion extending substantially perpendicularly from the fourth base portion, the eighth plate portion being opposite the seventh plate portion,

the fourth base portion of the stiffening member is opposite and spaced from the second base portion of the second strut,

the seventh plate portion of the reinforcement member is coupled to the third plate portion of the second strut, an

The eighth plate portion of the reinforcement member is coupled to the fourth plate portion of the second strut.

4. The frame of an image forming apparatus according to claim 3, wherein

The second frame includes: a side plate disposed opposite to the second pillar in a rotational axis direction of the second conveying roller; and a stay coupled to the second strut and the side plate, an

The stay is coupled to the second strut such that the stay forms a rectangular cross section together with the second base portion, the third plate portion, and the fourth plate portion of the second strut in the vertical direction at least between the coupling member and the reinforcing member.

5. The frame of an image forming apparatus according to claim 1, wherein

The third plate portion of the second strut includes an engaging portion that engages with the engaged portion at the first plate portion of the first strut, and

due to the engagement of the engaging portion with the engaged portion, the movement of the second stay relative to the first stay in the direction intersecting the vertical direction is regulated.

6. The frame of an image forming apparatus according to claim 5, wherein

The engaged portion is a concave portion that is depressed downward at a part of an upper end portion of the first plate portion of the first stay, an

The engaging portion is a projection at a lower end portion of the third plate portion of the second strut.

7. The frame of an image forming apparatus according to claim 1, wherein

The coupling member is coupled to each of the first and second struts by a screw.

8. The frame of an image forming apparatus according to claim 1, wherein

The coupling member is coupled to each of the first and second struts by welding.

9. The frame of an image forming apparatus according to claim 1, wherein

The first frame includes: a third pillar opposed to the first pillar in a direction orthogonal to a direction of a rotation axis of the first conveying roller and a vertical direction; a first rear plate opposed to the first pillar and the third pillar in a direction of a rotation axis of the first conveying roller; and a bottom plate provided at respective lower portions of the first stay, the third stay, and the first rear plate in the vertical direction such that the first stay, the third stay, and the first rear plate are fixed to the bottom plate, an

The second frame includes: a fourth stay that is opposite to the second stay in a direction orthogonal to the direction of the rotation axis of the second conveying roller and the vertical direction, the fourth stay being coupled to the third stay; and a second rear plate opposed to the second pillar and the fourth pillar in a direction of a rotation axis of the second conveying roller, the second rear plate being coupled to the first rear plate.

10. The frame of an image forming apparatus according to claim 9, further comprising:

another coupling member coupling the third strut and the fourth strut, wherein

The third strut includes: a fifth base portion; a ninth plate portion extending substantially perpendicularly from the fifth base portion; and a tenth plate portion extending substantially perpendicularly from the fifth base portion, the tenth plate portion being opposite to the ninth plate portion,

the fourth pillar includes: a sixth base portion provided at an upper portion of the fifth base portion in the vertical direction, the sixth base portion being in contact with the fifth base portion; an eleventh plate part extending substantially perpendicularly from the sixth base part, the eleventh plate part being provided at an upper portion of the ninth plate part in the vertical direction; and a twelfth plate portion extending substantially perpendicularly from the sixth base portion, the twelfth plate portion being opposite to the eleventh plate portion, the twelfth plate portion being provided at an upper portion of the tenth plate portion in the vertical direction, and

the other coupling member includes: a seventh base portion opposite and spaced apart from the fifth and sixth base portions; a thirteenth plate portion extending substantially perpendicularly from the seventh base portion, the thirteenth plate portion being coupled to the ninth plate portion and the eleventh plate portion; and a fourteenth plate portion extending substantially perpendicularly from the seventh base portion, the fourteenth plate portion being opposite to the thirteenth plate portion, the fourteenth plate portion being coupled to the tenth plate portion and the twelfth plate portion.

11. The frame of an image forming apparatus according to claim 9, further comprising:

a first coupling stay coupling a first pillar and a first rear plate; and

a second linking stay coupling the third post and the first back plate, wherein

The first and second coupling stays guide a sliding movement of the sheet cassette.

12. The frame of an image forming apparatus according to claim 9, further comprising:

a support member configured to support the light conductor together with the second rear plate, the support member being coupled to the second and fourth pillars.

13. An image forming apparatus includes:

the frame of claim 1;

a sheet cassette configured to accommodate sheets;

a first conveyance roller configured to convey a sheet fed from a sheet cassette;

a second conveyance roller configured to convey the sheet conveyed by the first conveyance roller; and

an image forming unit configured to form an image on the sheet conveyed by the second conveying roller.

Technical Field

The present invention relates to an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer (e.g., a laser beam printer or an LED printer), and to a frame that supports each unit of the image forming apparatus.

Background

Conventionally, there is known a configuration in which a first frame and a second frame disposed above the first frame in the vertical direction are coupled together as a frame of an image forming apparatus, similarly to the configuration in japanese patent laid-open No. 2000-77858. The first frame supports a sheet cassette accommodating sheets and a first conveyance roller conveying the sheets extracted from the sheet cassette. The second frame supports a second conveying roller that receives the sheet from the first conveying roller and conveys the sheet, and an image forming unit that forms an image on the sheet conveyed by the second conveying roller.

In the image forming apparatus, the above-described sheet cassette and first conveyance roller are positioned on a first frame, and the image forming unit and second conveyance roller are positioned on a second frame. The first frame and the second frame each include a plurality of struts extending in a vertical direction and a plurality of stays coupling the plurality of struts together. The sheet cassette and the first conveying roller are positioned and fixed directly or indirectly to a plurality of posts of the first frame. The image forming unit and the second conveying roller are positioned and fixed directly or indirectly to a plurality of posts of the second frame. Therefore, a lower positional accuracy between the pillars of the first frame and the pillars of the second frame results in a larger deviation in the relative position between the first conveying roller and the second conveying roller.

According to the configuration in japanese patent laid-open No.2000-77858, the second frame is mounted on the first frame by fitting the pins provided at the stays of the first frame into the mounting holes provided at the stays of the second frame, which results in positioning and coupling between the first frame and the second frame. This coupling between the first frame and the second frame results in an indirect positioning between the struts of the first frame and the struts of the second frame.

With such a coupling between the first frame and the second frame as in japanese patent laid-open No.2000-77858, if the rigidity of the coupling portion is low, the coupling portion is deformed due to an impact applied at the time of conveyance of the image forming apparatus or a load of the apparatus itself, so that the relative positional accuracy between the first pillar and the second pillar may deteriorate.

The deterioration of the relative positional accuracy between the first and second pillars causes the deterioration of the relative positional accuracy between the first and second conveyance rollers depending on the positional accuracy between the first and second pillars. In this case, when the sheet is fed from the first conveyance roller to the second conveyance roller, the sheet is skewed, which causes an image position deviation of the sheet, so that image formation quality may be deteriorated.

Disclosure of Invention

It is desirable to provide a frame of an image forming apparatus that enables to enhance rigidity of a coupling portion between a first pillar of a first frame and a second pillar of a second frame, the second pillar being provided at an upper portion of the first pillar in a vertical direction.

According to a representative configuration of the present invention, there is provided a frame of an image forming apparatus, including:

a first frame configured to support: a sheet cassette configured to accommodate sheets; and a first conveyance roller configured to convey a sheet extracted from the sheet cassette;

a second frame disposed vertically above the first frame, the second frame coupled to the first frame, the second frame configured to support: a second conveyance roller configured to receive the sheet conveyed by the first conveyance roller and convey the sheet; and an image forming unit configured to form an image on the sheet conveyed by the second conveying roller; and

a first strut configured to be part of a first frame, the first strut comprising: a first base portion; a first plate portion extending substantially perpendicularly from the first base portion; and a second plate portion extending substantially perpendicularly from the first base portion, the second plate portion being opposite the first plate portion;

a second strut configured as part of a second frame, the second strut comprising: a second base portion disposed vertically above the first base portion, the second base portion being in contact with the first base portion; a third plate portion extending substantially perpendicularly from the second base portion, the third plate portion being disposed vertically above the first plate portion; and a fourth plate portion extending substantially perpendicularly from the second base portion, the fourth plate portion being opposite the third plate portion, the fourth plate portion being disposed vertically above the second plate portion,

a coupling member coupling the first strut and the second strut, the coupling member comprising: a third base portion opposite and spaced apart from the first and second base portions; a fifth plate portion extending substantially perpendicularly from the third base portion, the fifth plate portion coupled to the first plate portion and the third plate portion; and a sixth plate portion extending substantially perpendicularly from the third base portion, the sixth plate portion being opposite the fifth plate portion, the sixth plate portion being coupled to the second plate portion and the fourth plate portion.

Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Drawings

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. 3 is an exploded perspective view of a frame of the image forming apparatus;

fig. 4 is a perspective view of a frame of the image forming apparatus;

FIG. 5A is a perspective view of the upper right strut; FIG. 5B is a cross-sectional view of the right upper strut;

FIG. 6A is a perspective view of the lower right strut; FIG. 6B is a cross-sectional view of the lower right strut;

FIG. 7A is a sectional view taken along line K3-K3 of a frame of the image forming apparatus; FIG. 7B is a sectional view taken along line K4-K4 of the frame of the image forming apparatus; FIG. 7C is a sectional view taken along line K5-K5 of the frame of the image forming apparatus;

FIG. 8A is a perspective view of the upper right strut and the lower right strut before coupling; FIG. 8B is a perspective view of the upper right strut and the lower right strut coupled together; FIG. 8C is a perspective view of the upper right strut and the lower right strut coupled together;

FIG. 9A is a plan view of the upper right strut and the lower right strut before coupling; FIG. 9B is a plan view of the upper right strut and the lower right strut coupled together; FIG. 9C is a plan view of the upper right strut and the lower right strut coupled together;

FIG. 10A is a perspective view of the upper right strut and the lower right strut according to the second embodiment prior to coupling; FIG. 10B is a perspective view of the upper right strut and the lower right strut according to the second embodiment coupled together; FIG. 10C is a perspective view of the upper right strut and the lower right strut according to the second embodiment coupled together;

FIG. 11A is a plan view of the upper right strut and the lower right strut according to the second embodiment prior to coupling; FIG. 11B is a plan view of the upper right strut and the lower right strut according to the second embodiment coupled together; FIG. 11C is a plan view of the upper right strut and the lower right strut according to the second embodiment coupled together; and

fig. 12 is a schematic sectional view of an image forming apparatus according to another embodiment.

Detailed Description

(first embodiment)

< image Forming apparatus >

The overall configuration of the image forming apparatus according to the first embodiment of the present invention and the operation at the time of image formation will be described below with reference to the drawings. It should be noted that the scope of the present invention is not limited to the size, materials and shape of the following constituent elements and their relative configurations unless otherwise specified.

The image forming apparatus a according to the present embodiment is of an intermediate tandem type, which transfers four color toners of yellow Y, magenta M, cyan C, and black K to an intermediate transfer belt, and then transfers an image onto a sheet to form an image. Note that in the following description, members relating to yellow toner are denoted by Y as a suffix, members relating to magenta toner are denoted by M as a suffix, members relating to cyan toner are denoted by C as a suffix, and members relating to black toner are denoted by K as a suffix. However, the configuration and operation of the members are substantially the same except for the color of the toner. Therefore, when the distinction is not required, the suffix thereof will be appropriately omitted.

Fig. 1 is a schematic sectional view of an image forming apparatus a. As shown in fig. 1, the 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 to the image forming unit 10.

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

The feeding unit 20 includes: sheet cassettes 11a to 11c each accommodating a sheet S; and pickup rollers 12a to 12c each picking up the sheet S accommodated in the corresponding sheet cassette 11a, 11b, or 11 c. The feeding unit 20 includes: feed rollers 13a to 13c each of which feeds the sheet S picked up by the corresponding pickup roller 12a, 12b, or 12c to the conveying path; conveying rollers 14a to 14d each conveying the sheet S on the conveying path; and a registration roller 15.

When an image is formed by the image forming apparatus a, an imaging job signal is first input to a controller, not shown. This arrangement causes the sheet S accommodated in any of the sheet cassettes 11a to 11c to be picked up by the corresponding pickup roller 12a, 12b, or 12 c. Next, the sheet S is sent to the registration roller 15 by the corresponding feed roller 13a, 13b, or 13c and the conveying roller 14a, 14b, 14c, or 14 d. Thereafter, the sheet S is skew-corrected by the registration rollers 15. Then, at a predetermined time, the sheet S is sent to a secondary transfer portion formed by the secondary transfer roller 7 and the secondary transfer counter roller 8.

Meanwhile, in the image forming unit 10, first, the surface of the photosensitive drum 1Y is charged by the charging roller 2Y. Thereafter, the laser scanner unit 3 irradiates the surface of the photosensitive drum 1Y with laser light in accordance with image data transmitted from an unillustrated external equipment, thereby forming an electrostatic latent image on the surface of the photosensitive drum 1Y. Thereafter, the developing device 4Y attaches yellow toner to the electrostatic latent image formed on the surface of the photosensitive drum 1Y, thereby forming a yellow toner image on the surface of the photosensitive drum 1Y. In response to application of a primary transfer bias to the primary transfer roller 5Y, the toner image formed on the surface of the photosensitive drum 1Y is primarily transferred to the intermediate transfer belt 6.

In a similar process, a magenta toner image, a cyan toner image, and a black toner image are formed on the photosensitive drums 1M, 1C, and 1K, respectively. Then, in response to application of a primary transfer bias to each of the primary transfer rollers 5M, 5C, and 5K, the corresponding toner image is transferred so as to be superimposed on the yellow toner image on the intermediate transfer belt 6. This arrangement results in formation of a full-color toner image corresponding to an image signal on the surface of the intermediate transfer belt 6. Note that after the primary transfer, the toners adhering to the photosensitive drums 1Y, 1M, 1C, and 1K are each removed by a cleaning member, not shown, so that they are collected in the toner collection container 18.

Thereafter, the full-color toner image is sent to the secondary transfer portion by the circumferential running of the intermediate transfer belt 6. Then, in response to application of a secondary transfer bias to the secondary transfer roller 7, the full-color toner image on the intermediate transfer belt 6 is transferred onto the sheet S at the secondary transfer portion. The sheet S to which the toner image is transferred is conveyed to the fixing device 9 by a conveying roller 14 e. Then, the sheet S is heated and pressed by the fixing device 9, so that the toner image on the sheet S is fixed onto the sheet S. Thereafter, the sheet S to which the toner image is fixed is discharged to a discharge tray 19 by a discharge roller 17.

< frame for image Forming apparatus >

Next, the configuration of the frame 100 for the image forming apparatus a will be described.

Fig. 2 is a perspective view of the frame 100 for the image forming apparatus a. Fig. 3 is an exploded perspective view of the frame 100 for the image forming apparatus a. As shown in fig. 2 and 3, the frame 100 for the image forming apparatus a includes an upper frame 50 and a lower frame 70 coupled together. The upper frame 50 and the lower frame 70 are each made of a metal plate. The upper frame 50 is provided at an upper portion of the lower frame 70 in the vertical direction. It should be noted that, as with the frame 100, the lower frame 70 is generally to be combined with the image forming apparatus a, and therefore is different from a cassette base unit that is optionally attached as an option for function expansion, such as increasing the number of sheets S to be accommodated. The dotted line shown in fig. 1 indicates the boundary between the upper frame 50 and the lower frame 70.

The upper frame 50 (second frame) includes a front plate 53, a rear plate 52, and stays 58, 59, 60, and 61 that couple the front plate 53 and the rear plate 52 together. The front plate 53 includes a right upper pillar 54 (second pillar), a left upper pillar 55, and stays 56 and 57 that couple the right and left upper pillars 54 and 55 together. Stays 56 and 57 are welded to right upper strut 54 and left upper strut 55. Brace 58 is welded to right upper brace 54 and back plate 52. Brace 59 is welded to left upper strut 55 and rear plate 52. Braces 60 and 61 are welded to brace 56 and back plate 52.

The lower frame 70 (first frame) includes a front plate 73, a rear plate 72, stays 77 and 78 that couple the front plate 73 and the rear plate 72 together, and a bottom plate 71. The front plate 73 includes a right lower pillar 74 (first pillar), a left lower pillar 75, and a stay 76 that couples the right lower pillar 74 and the left lower pillar 75 together. The stay 76 is welded to the right lower strut 74 and the left lower strut 75. Brace 77 is welded to right lower strut 74 and rear plate 72. The stay 78 is welded to the left lower stay 75 and the rear plate 72.

Fig. 4 shows a frame 100 for the image forming apparatus a to which members supporting the photosensitive drum 1 and the sheet cassette 11 are attached. As shown in fig. 4, the supporting member 81 that supports the photosensitive drum 1 and the developing device 4 is positioned and attached to the right upper post 54 and the left upper post 55 of the upper frame 50. The supporting member 81 rotatably supports one end portion in the rotational axis direction of each of the photosensitive drum 1 and a developing sleeve (not shown) included in the developing device 4. The other end portion in the rotational axis direction of each of the photosensitive drum 1 and the developing sleeve is rotatably supported by the rear plate 52.

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

A front plate as a frame on the front side of the fixing and conveying unit 84 including the fixing device 9 and the conveying roller 14e combined together is attached to the right and left upper support columns 54 and 55 of the upper frame 50. The position of the fixing and conveying unit 84 relative to the right and left upper stays 54 and 55 is determined by fitting pins (not shown) on the front plate of the fixing and conveying unit 84 one-to-one to fitting holes 54a2c formed on the right upper stay 54 and fitting holes 55a formed on the left upper stay 55.

The conveying roller 14d (second conveying roller) is supported by a frame of the fixing and conveying unit 84. That is, determining the positions of the fixing and conveying unit 84 with respect to the upper right and left stays 54 and 55 results in determining the position of the conveying roller 14 d. One end portion in the rotational axis direction of the conveying roller 14a (first conveying roller) which feeds the sheet S to the conveying roller 14d is positioned to the right lower stay 74 and is then rotatably supported by the right lower stay 74. The other end portion in the rotational axis direction of the conveying roller 14a is rotatably supported by the rear plate 52.

The support rail 83a supporting the sheet cassette 11a, the support rail 83b supporting the sheet cassette 11b, and the support rail 83c supporting the sheet cassette 11c are positioned and attached to each of the right and left lower posts 74, 75 of the lower frame 70. The support rails 83a, 83b, and 83c function as stays (first coupling stays and second coupling stays) that couple the right lower column 74, the left lower column 75, and the rear plate 72 together. At a position between the right lower stay 74 and the left lower stay 75, the sheet cassettes 11a to 11c are slidably moved while being guided by the support rails 83a to 83c, so as to be inserted in the direction of arrow Y or pulled out in the direction of arrow Y.

In the present embodiment, the front face of the image forming apparatus a is oriented in the direction of arrow Y, the sheet cassettes 11a to 11c can be pulled out in the direction of arrow Y, and the back face of the image forming apparatus a is oriented in the direction of arrow-Y, in which the sheet cassettes 11a to 11c can be inserted. The right side of the image forming apparatus a is oriented in the direction of arrow X, which is orthogonal to the directions of arrows Y and-Y and in the directions of vertical arrows Z and-Z. The left side face of the image forming apparatus a is oriented in the arrow-X direction opposite to the arrow X direction. That is, the right and left lower pillars 74, 75 are disposed opposite the rear plate 72 in the lower frame 70 in the moving direction of the sheet cassettes 11a to 11 c. The right and left lower pillars 74, 75 are disposed opposite to each other in a direction orthogonal to the moving direction and the vertical direction of the sheet cassettes 11a to 11 c.

< support column >

Next, the configuration of the support post for the frame 100 of the image forming apparatus a will be described in detail. Note that the right upper pillar 54 and the right lower pillar 74 will be described below, and are similar in configuration to the left upper pillar 55 (fourth pillar) and the left lower pillar 75 (third pillar), respectively.

Fig. 5A is a perspective view of the upper right pillar 54. FIG. 5B is a cross-sectional view of the upper right strut 54 taken along line K1-K1 of FIG. 5A. As shown in fig. 5A and 5B, the right upper support column 54 includes an outer member 54a and an inner member 54B coupled by unshown screws. Note that a configuration in which the outer member 54a and the inner member 54b are coupled by welding, a configuration in which the outer member 54a and the inner member 54b are integrally molded by casting or punching, or a configuration in which the outer member 54a and the inner member 54b are integrally formed by cutting may be provided.

The outer member 54a includes: base portion 54a1 (second base portion); a curved portion 54a2 (third plate portion) which is one end portion of the base portion 54a1 that is bent substantially perpendicularly; and a bent portion 54a3 (fourth plate portion) which is the other end portion of the base portion 54a1 that is bent substantially perpendicularly and is opposed to the bent portion 54a 2. Therefore, the outer member 54a has a U shape as a whole. Note that, in the present embodiment, the U-shape of the exterior member 54a is obtained from one piece of metal plate subjected to bending. However, the substantially U-shape may be formed by combining two sheets of metal plates each having an L-shape. The meaning of "substantially perpendicular" herein includes not only that the bent portions 54a2 and 54a3 are at a 90 degree angle with respect to the base portion 54a1, but also, for example, 89 to 91 degree angles in view of dimensional tolerances and manufacturing tolerances. The curved portions 54a2 and 54a3 may each have a step, so long as the curved portions 54a2 and 54a3 oppose each other substantially perpendicular to the base portion 54a 1. Curved portions 54a2 and 54a3 may each have a shape that resembles an arc relative to base portion 54a 1.

The inner member 54b includes: base portion 54b1 (fourth base portion); a curved portion 54b2 (seventh plate portion) which is one end portion of the base portion 54b1 that is bent substantially perpendicularly; and a bent portion 54b3 (eighth plate portion) which is the other end portion of the base portion 54b1 that is bent substantially perpendicularly and is opposed to the bent portion 54b 2. The inner member 54b has a U-shape as a whole. Note that, in the present embodiment, the U-shape of the inner member 54b is obtained from one piece of metal plate subjected to bending. However, the substantially U-shape may be formed by combining two sheets of metal plates each having an L-shape. The meaning of "substantially perpendicular" herein includes not only that the bent portions 54b2 and 54b3 are at a 90 degree angle with respect to the base portion 54b1, but also, for example, 89 to 91 degree angles in view of dimensional tolerances and manufacturing tolerances. The curved portions 54b2 and 54b3 may each have a step, so long as the curved portions 54b2 and 54b3 oppose each other substantially perpendicular to the base portion 54b 1. Curved portions 54b2 and 54b3 may each have a shape that resembles an arc relative to base portion 54b 1.

The outer member 54a and the inner member 54b are arranged such that their U-shaped opening portions face each other. That is, the base portion 54b1 of the inner member 54b is spaced apart from and opposite the base portion 54a1 of the outer member 54 a. The curved portion 54b2 of the inner member 54b is coupled to the curved portion 54a2 of the outer member 54a by screws, not shown. The curved portion 54b3 of the inner member 54b is coupled to the curved portion 54a3 of the outer member 54a by screws, not shown. This arrangement ensures the rigidity of the right upper support 54 having a rectangular sectional shape. That is, the inner member 54b is a part of the right upper pillar 54, and functions as a reinforcing member that reinforces the outer member 54 a.

Curved portion 54a2 of outer member 54a has a threaded hole 54a2b and curved portion 54a3 of outer member 54a has a threaded hole 54a3 a. The lower end portion of the curved portion 54a2 of the exterior member 54a is provided with a protrusion 54a2a (engaging portion) that protrudes in the direction of the arrow Y. In the case where the lower end portion of the outer member 54a is located below the lower end portion of the inner member 54b, there is provided a receiving portion 54a4 which has a space due to a part of the outer member 54a protruding below the inner member 54b and which receives the right lower support 74.

Fig. 6A is a perspective view of the lower right pillar 74. FIG. 6B is a cross-sectional view of lower right strut 74 taken along line K2-K2 of FIG. 6A. As shown in fig. 6A and 6B, the lower right pillar 74 includes an outer member 74a and an inner member 74B coupled by unshown screws. It should be noted that a configuration in which the outer member 74a and the inner member 74b are coupled by welding, a configuration in which the outer member 74a and the inner member 74b are integrally molded by casting or stamping, or a configuration in which the outer member 74a and the inner member 74b are integrally formed by cutting may be provided.

The outer member 74a includes: base portion 74a1 (first base portion); a curved portion 74a2 (first plate portion) which is one end portion of the base portion 74a1 that is bent substantially perpendicularly; and a bent portion 74a3 (second plate portion) which is the other end portion of the base portion 74a1 that is bent substantially perpendicularly, and which is opposite to the bent portion 74a 2. The outer member 74a has a U-shape as a whole. Note that, in the present embodiment, the U-shape of the exterior member 74a is obtained from one piece of metal plate subjected to bending. However, the substantially U-shape may be formed by combining two sheets of metal plates each having an L-shape. The meaning of "substantially perpendicular" herein includes not only that the bent portions 74a2 and 74a3 are at a 90 degree angle relative to the base portion 74a1, but also, for example, 89 to 91 degree angles in view of dimensional tolerances and manufacturing tolerances. The curved portions 74a2 and 74a3 may each have a step, so long as the curved portions 74a2 and 74a3 oppose each other substantially perpendicular to the base portion 74a 1. Curved portions 74a2 and 74a3 may each have a shape that resembles an arc relative to base portion 74a 1.

The inner member 74b includes: base portion 74b1 (third base portion); a bent portion 74b2 (fifth plate portion) which is one end portion of the base portion 74b1 that is bent substantially perpendicularly; and a bent portion 74b3 (sixth plate portion) which is the other end portion of the base portion 74b1 that is bent substantially perpendicularly, and which is opposite to the bent portion 74b 2. The inner member 74b has a U-shape as a whole. Note that, in the present embodiment, the U-shape of the inner member 74b is obtained from one piece of metal plate subjected to bending. However, the substantially U-shape may be formed by combining two pieces of metal plates each having an L-shape. The meaning of "substantially perpendicular" herein includes not only that the bent portions 74b2 and 74b3 are at a 90 degree angle relative to the base portion 74b1, but also, for example, 89 to 91 degree angles in view of dimensional tolerances and manufacturing tolerances. The curved portions 74b2 and 74b3 may each have a step, so long as the curved portions 74b2 and 74b3 oppose each other substantially perpendicular to the base portion 74b 1. Curved portions 74b2 and 74b3 may each have a shape that resembles an arc relative to base portion 74b 1.

The outer member 74a and the inner member 74b are arranged such that their U-shaped opening portions face each other. That is, the base portion 74b1 of the inner member 74b is spaced apart from and opposite the base portion 74a1 of the outer member 74 a. The curved portion 74b2 of inner member 74b is coupled to the curved portion 74a2 of outer member 74a by screws, not shown. The curved portion 74b3 of inner member 74b is coupled to the curved portion 74a3 of outer member 74a by screws, not shown. This arrangement ensures the rigidity of the right lower pillar 74 having a rectangular sectional shape. That is, the inner member 74b is a part of the right lower pillar 74, and it serves as a reinforcing member that reinforces the right lower pillar 74.

Curved portion 74b2 of inner member 74b has a threaded hole 74b2a, and curved portion 74b3 of inner member 74b has a threaded hole 74b3 a. The upper end portion of the curved portion 74a2 of the outer member 74a is provided with a concave portion 74a2a (engaged portion) that is concave downward in the vertical direction. With the upper end portion of the inner member 74b located above the upper end portion of the outer member 74a, the portion of the inner member 74b projecting above the outer member 74a serves as a projecting portion 74b4 that is received by the receiving portion 54a4 of the right upper strut 54.

Fig. 7A is a sectional view of the frame 100 of the image forming apparatus a taken along line K3-K3 of fig. 2. Fig. 7B is a sectional view of the frame 100 of the image forming apparatus a taken along line K4-K4 of fig. 2. Fig. 7C is a sectional view of the frame 100 of the image forming apparatus a taken along line K5-K5 of fig. 2.

As shown in FIG. 7A, the cross-sectional shape at the location of line K3-K3 of FIG. 2 is rectangular due to the outer member 54a and the inner member 54b of the right upper strut 54. Specifically, the base portion 54a1, curved portion 54a2 and curved portion 54a3 of the outer member 54a and the base portion 54b1 of the inner member 54b serve as sides of a rectangular cross-section. It should be noted that the curved portion 54a2 of the outer member 54a and the curved portion 54b2 of the inner member 54b are disposed to overlap each other, and the curved portion 54a3 of the outer member 54a and the curved portion 54b3 of the inner member 54b are disposed to overlap each other.

As shown in fig. 7B, the sectional shape at the position of line K4-K4 of fig. 2 is rectangular due to the outer member 54a and the stay 58 of the right upper strut 54. Specifically, base portion 54a1, curved portion 54a2 and curved portion 54a3 of outer member 54a and brace 58 serve as the sides of the rectangular cross-section. That is, the stay 58 is coupled to the right upper pillar 54 such that between the inner member 54b of the right upper pillar 54 and the inner member 74b of the right lower pillar 74, the stay 58 forms a rectangular cross section in the vertical direction together with the base portion 54a1, the bent portion 54a2, and the bent portion 54a3 of the outer member 54 a.

As shown in fig. 7C, the cross-sectional shape at the position of line K5-K5 of fig. 2 is rectangular due to the outer member 54a of the right upper strut 54 and the inner member 74b of the right lower strut 74. Specifically, the base portion 54a1, the bent portion 54a2 and the bent portion 54a3 of the outer member 54a in the right upper support pillar 54 and the base portion 74b1 of the inner member 74b in the right lower support pillar 74 serve as sides of a rectangular cross section. It is to be noted that the bent portion 54a2 of the outer member 54a in the right upper pillar 54 and the bent portion 74b2 of the inner member 74b in the right lower pillar 74 are disposed so as to overlap each other, and the bent portion 54a3 of the outer member 54a in the right upper pillar 54 and the bent portion 74b3 of the inner member 74b in the right lower pillar 74 are disposed so as to overlap each other.

As described above, as the pillar on the right side of the frame 100 of the image forming apparatus a, most of the right upper pillar 54 and the right lower pillar 74 are rectangular in sectional shape regardless of the position, thereby enhancing the rigidity. Similarly, as the pillar on the left side of the frame 100 of the image forming apparatus a, most of the left upper pillar 55 and the left lower pillar 75 are rectangular in cross-sectional shape regardless of position, thereby enhancing rigidity. It should be noted that the coupling portion between the right upper strut 54 and the right lower strut 74 is located at the position of line K5-K5 of fig. 2. As described above, the cross-sectional shape of the coupling portion between the right upper strut 54 and the right lower strut 74 is rectangular, so that the rigidity of the coupling portion between each strut is enhanced. Note that, in the present embodiment, the sectional shape of each pillar is rectangular. However, any quadrangle (such as a square) enables to enhance rigidity, and thus the sectional shape may be square.

< arrangement of coupling struts >

As described above, the image forming unit 10, the sheet cassettes 11a to 11c, and the conveying rollers 14a and 14d are directly or indirectly positioned by the right upper support 54, the right lower support 74, the left upper support 55, and the left lower support 75. Therefore, in coupling the upper frame 50 and the lower frame 70, a low relative positional accuracy between the right upper pillar 54 and the right lower pillar 74 or a low relative positional accuracy between the left upper pillar 55 and the left lower pillar 75 causes deterioration in the relative positional accuracy between the conveying roller 14a and the conveying roller 14 d. In this case, when the sheet S is fed from the conveying roller 14a to the conveying roller 14d, the sheet S is skewed, which causes an image position deviation of the sheet S, so that image formation quality may be deteriorated. Note that the registration rollers 15 perform skew correction on the sheet S, but a certain degree of skew of the sheet S may cause the skew correction to fail. Therefore, in the present embodiment, the following configuration suppresses deterioration in the relative positional accuracy between each of the pillars.

Fig. 8A, 8B, and 8C are each perspective views of the right upper support 54 and the right lower support 74. The coupling process of the right upper pillar 54 and the right lower pillar 74 is shown in the order of fig. 8A, 8B, and 8C. Fig. 9A, 9B, and 9C each show the right upper strut 54 and the right lower strut 74 as viewed in the direction of arrow-X. The coupling process of the right upper pillar 54 and the right lower pillar 74 is shown in the order of fig. 9A, 9B, and 9C.

As shown in fig. 8A, 8B, 9A, and 9B, in coupling the right upper pillar 54 and the right lower pillar 74, first, the worker moves the right upper pillar 54 downward in the vertical direction to insert the protruding portion 74B4 of the right lower pillar 74 into the receiving portion 54a4 of the right upper pillar 54. At this time, as the bent portions 54a2 and 54a3 of the right upper strut 54 come into contact with the bent portions 74b2 and 74b3 of the right lower strut 74, the right upper strut 54 is guided to move in the vertical direction. The spacing L1 between the inner surface of the curved portion 54a2 and the inner surface of the curved portion 54a3 of the right upper strut 54 is 0.5 mm wider than the spacing L2 between the outer surface of the curved portion 74b2 and the outer surface of the curved portion 74b3 of the right lower strut 74. Therefore, when the protruding portion 74b4 of the right lower pillar 74 is inserted into the receiving portion 54a4 of the right upper pillar 54, the position of the right upper pillar 54 in the arrow Y direction with respect to the right lower pillar 74 is determined with a play of 0.5 mm.

Next, as shown in fig. 8C and 9C, the worker further moves the right upper support column 54 downward in the vertical direction. Therefore, the abutting portion 54a1a as the lower end portion of the base portion 54a1 of the right upper strut 54 abuts on the abutting portion 74a1a as the upper end portion of the base portion 74a1 of the right lower strut 74, thereby determining the position of the right upper strut 54 in the vertical direction with respect to the right lower strut 74. The protrusion 54a2a at the curved portion 54a2 of the right upper strut 54 mates with (engages with) the recessed portion 74a2a at the curved portion 74a2 of the right lower strut 74. Therefore, the position of the right upper pillar 54 in the direction of the arrow X (i.e., the movement in the direction orthogonal to (intersecting with) the vertical direction) with respect to the right lower pillar 74 is regulated, thereby determining the position in the direction orthogonal to (intersecting with) the vertical direction.

Due to this positioning between the right upper strut 54 and the right lower strut 74, the base portion 74a1 of the outer member 74a of the right lower strut 74 is disposed adjacent to the base portion 54a1 of the outer member 54a of the right upper strut 54 in the vertical direction. The upper end portion of the base portion 74a1 of the outer member 74a is in contact with the lower end portion of the base portion 54a1 of the outer member 54 a. The curved portion 74a2 of the outer member 74a of the right lower strut 74 is disposed adjacent in the vertical direction to the curved portion 54a2 of the outer member 54a of the right upper strut 54. The curved portion 74a3 of the outer member 74a of the right lower strut 74 is disposed adjacent in the vertical direction to the curved portion 54a3 of the outer member 54a of the right upper strut 54.

Next, the worker inserts screws (not shown) into the screw holes 54a2b at the bent portion 54a2 of the outer member 54a of the right upper pillar 54 and the screw holes 74b2a at the bent portion 74b2 of the inner member 74b of the right lower pillar 74, thereby performing fastening. The worker inserts screws (not shown) into the screw holes 54a3a at the bent portion 54a3 of the outer member 54a of the right upper pillar 54 and the screw holes 74b3a at the bent portion 74b3 of the inner member 74b of the right lower pillar 74, thereby fastening. Thus, right upper strut 54 and right lower strut 74 are coupled together. Thus, the position of the right upper pillar 54 in the arrow Y direction, that is, the position in the direction orthogonal (intersecting) to the vertical direction, with respect to the right lower pillar 74 is determined. As described above, due to the fitting between the protrusion 54a2a of the right upper pillar 54 and the concave portion 74a2a of the right lower pillar 74 and the screw fastening between the right upper pillar 54 and the right lower pillar 74, the right upper pillar 54 and the right lower pillar 74 are fixed with all-directional position determination in the direction orthogonal to the vertical direction. That is, in the present embodiment, the inner member 74b of the right lower pillar 74 is a part of the right lower pillar 74, and serves as a coupling member that couples the right upper pillar 54 and the right lower pillar 74. It should be noted that the inner member 74b of the right lower strut 74 and the outer member 54a of the right upper strut 54 may be coupled by welding.

As described above, in the present embodiment, the positioning between the right upper support 54 and the right lower support 74 is directly performed by the two supports. Therefore, compared with a configuration in which positioning between right upper pillar 54 and right lower pillar 74 is performed indirectly by a member attached to right upper pillar 54 and right lower pillar 74, the influence of tolerance is low, so that deterioration in the accuracy of the relative position between right upper pillar 54 and right lower pillar 74 can be suppressed. Therefore, when the sheet S is fed from the conveying roller 14a to the conveying roller 14d, the sheet S is suppressed from skewing, so that deviation of the image position of the sheet S can be suppressed.

(second embodiment)

Next, a frame of an image forming apparatus a according to a second embodiment of the present invention will be described with reference to the drawings. The same components as those according to the first embodiment are denoted by the same reference numerals, and thus the description thereof will be omitted.

Fig. 10A, 10B, and 10C are each a perspective view of the right upper support column 54 and the right lower support column 74 according to the present embodiment. The coupling process of the right upper pillar 54 and the right lower pillar 74 is shown in the order of fig. 10A, 10B, and 10C. Fig. 11A, 11B, and 11C each show the right upper support column 54 and the right lower support column 74 according to the present embodiment as viewed in the arrow-X direction. The coupling process of the right upper pillar 54 and the right lower pillar 74 is shown in the order of fig. 11A, 11B, and 11C.

As shown in fig. 10A and 11A, in the present embodiment, the upper end portion of the outer member 74a is located above the upper end portion of the inner member 74b in the right lower pillar 74. A receiving portion 74a4 is provided that has space due to a portion of the outer member 74a protruding above the inner member 74b and receives the right upper strut 54. With the lower end portion of the inner member 54b located below the lower end portion of the outer member 54a in the right upper leg 54, the portion of the inner member 54b that protrudes below the outer member 54a serves as a protruding portion 54b4 that is received by the receiving portion 74a4 of the right lower leg 74. That is, in contrast to the first embodiment, in the present embodiment, the right lower support pillar 74 has the receiving portion 74a4, and the right upper support pillar 54 has the protruding portion 54b 4. The other configuration is similar to that according to the first embodiment.

As shown in fig. 10B and 11B, in coupling the right upper pillar 54 and the right lower pillar 74, first, the worker moves the right upper pillar 54 downward in the vertical direction to insert the protruding portion 54B4 of the right upper pillar 54 into the receiving portion 74a4 of the right lower pillar 74. At this time, the right upper pillar 54 is guided to move in the vertical direction as the curved portions 54b2 and 54b3 of the right upper pillar 54 come into contact with the curved portions 74a2 and 74a3 of the right lower pillar 74. The spacing L3 between the outer surface of the curved portion 54b2 and the outer surface of the curved portion 54b3 of the right upper strut 54 is 0.5 mm narrower than the spacing L4 between the inner surface of the curved portion 74a2 and the inner surface of the curved portion 74a3 of the right lower strut 74. Therefore, when the protruding portion 54b4 of the right upper strut 54 is inserted into the receiving portion 74a4 of the right lower strut 74, the position of the right upper strut 54 in the arrow Y direction with respect to the right lower strut 74 is determined with a play of 0.5 mm.

Next, as shown in fig. 10C and 11C, the worker further moves the right upper column 54 downward in the vertical direction. Therefore, the abutting portion 54a1a as the lower end portion of the base portion 54a1 of the right upper strut 54 abuts on the abutting portion 74a1a as the upper end portion of the base portion 74a1 of the right lower strut 74, thereby determining the position of the right upper strut 54 in the vertical direction with respect to the right lower strut 74. The protrusion 54a2a at the bent portion 54a2 of the right upper strut 54 is fitted to the recessed portion 74a2a at the bent portion 74a2 of the right lower strut 74. Thus, the position of the right upper pillar 54 relative to the right lower pillar 74 in the arrow X direction is determined.

Due to this positioning between the right upper strut 54 and the right lower strut 74, the base portion 74a1 of the outer member 74a of the right lower strut 74 is disposed adjacent to the base portion 54a1 of the outer member 54a of the right upper strut 54 in the vertical direction. The upper end portion of the base portion 74a1 of the outer member 74a is in contact with the lower end portion of the base portion 54a1 of the outer member 54 a. The curved portion 74a2 of the outer member 74a of the right lower strut 74 is disposed adjacent in the vertical direction to the curved portion 54a2 of the outer member 54a of the right upper strut 54. The curved portion 74a3 of the outer member 74a of the right lower strut 74 is disposed adjacent in the vertical direction to the curved portion 54a3 of the outer member 54a of the right upper strut 54.

Next, the worker inserts screws (not shown) into the screw holes 54b2a at the bent portion 54b2 of the inner member 54b of the right upper pillar 54 and the screw holes 74a2b at the bent portion 74a2 of the outer member 74a of the right lower pillar 74, resulting in fastening. The worker inserts screws (not shown) into the screw holes 54b3a at the bent portion 54b3 of the inner member 54b of the right upper support column 54 and the screw holes 74a3a at the bent portion 74a3 of the outer member 74a of the right lower support column 74, thereby causing fastening. Thus, right upper strut 54 and right lower strut 74 are coupled together. That is, in the present embodiment, the inner member 54b of the right upper pillar 54 is a part of the right upper pillar 54, and functions as a coupling member that couples the right upper pillar 54 and the right lower pillar 74. Note that the inner member 54b of the right upper pillar 54 and the outer member 74a of the right lower pillar 74 may be coupled by welding.

As described above, in the present embodiment, the positioning between the right upper support 54 and the right lower support 74 is directly performed by the two supports. Therefore, the influence of the tolerance is lower than in a configuration in which positioning is performed by members attached to right upper pillar 54 and right lower pillar 74, so that deterioration in the accuracy of the relative position between right upper pillar 54 and right lower pillar 74 can be suppressed. Therefore, when the sheet S is fed from the conveying roller 14a to the conveying roller 14d, the sheet S is suppressed from skewing, so that deviation of the image position of the sheet S can be suppressed.

It should be noted that, in the present embodiment, the configuration has been given in which the image forming unit 10, the sheet cassettes 11a to 11c, and the conveying rollers 14a and 14d are positioned by the front plate 53 of the upper frame 50 and the front plate 73 of the lower frame 70. However, the present invention is not limited thereto. That is, these members may be positioned by the rear plate 52 of the upper frame 50 and the rear plate 72 of the lower frame 70. In this case, the coupling between the pillar of the rear plate 52 of the upper frame 50 and the pillar of the rear plate 72 of the lower frame 70 is performed similarly to the coupling between the right upper pillar 54 and the right lower pillar 74, so that a similar effect can be obtained.

The arrangement of each member supported by the upper frame 50 or the lower frame 70 may be changed as appropriate. For example, as shown in fig. 12, the sheet cassette 11a supported by the lower frame 70 can be miniaturized to accommodate small-sized sheets S. Further, the toner collecting container 18 may be disposed in a space resulting from miniaturization.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

The present application claims the benefit of Japanese patent application laid-open No.2020-086346, filed 5/15/2020, which is incorporated herein by reference in its entirety.