Image forming apparatus

Abstract

This mechanism prevents the mounting position of the retaining frame relative to the main frame, which has been adjusted by the position adjustment unit, from shifting when a strong external force is applied to the image forming apparatus. [Solution] An image forming apparatus comprising: a main frame 101a of the image forming apparatus; a holding frame 130 for holding components constituting the image forming apparatus; a position adjustment unit 140 for adjusting the mounting position of the holding frame relative to the main frame; and a fixing unit for fixing the holding frame to the main frame at the mounting position adjusted by the position adjustment unit, wherein the fixing unit includes a plurality of first fixing members 167a to 167d that fix from a first direction (X direction) perpendicular to the adjustment direction (Z direction) of the mounting position by the position adjustment unit, and a plurality of second fixing members 168a to 168d that fix from a second direction (Y direction) perpendicular to the adjustment direction, and the number of first fixing members and the number of second fixing members are the same.

Description

Technical Field

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

Background Art

[0002] Conventionally, an image forming apparatus having a main body frame of an image forming apparatus, a holding frame for holding components constituting the image forming apparatus, a position adjusting unit for adjusting an attachment position of the holding frame with respect to the main body frame, and a fixing unit for fixing the holding frame to the main body frame at the attachment position adjusted by the position adjusting unit is known.

[0003] For example, Patent Document1 discloses an electrophotographic image forming apparatus having a frame structure in which a writing frame (holding frame) for holding a latent image forming unit (component) is fixed to a main body frame with screws (fixing unit). The writing frame is screwed to two left and right front support columns and two left and right rear support columns constituting the main body frame, respectively, and is fixed to the main body frame. Further, a position adjusting member (position adjusting unit) for adjusting the height position (attachment position) of the writing frame with respect to the front support column is attached to one of the two left and right front support columns. By adjusting the height position of the writing frame with respect to the front support column with this position adjusting member, the writing frame is adjusted to a horizontal state.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional image forming apparatus, when a strong external force is applied to the image forming apparatus due to an impact received during transportation or use of the image forming apparatus, there is a problem that the attachment position of the holding frame with respect to the main body frame adjusted by the position adjusting unit is displaced.

Means for Solving the Problems

[0005] [[ID= 32]] To solve the above-mentioned problems, the present invention provides an image forming apparatus comprising: a main frame of the image forming apparatus; a holding frame for holding components constituting the image forming apparatus; a position adjustment unit for adjusting the mounting position of the holding frame with respect to the main frame; and a fixing unit for fixing the holding frame to the main frame at the mounting position adjusted by the position adjustment unit, wherein the fixing unit includes a plurality of first fixing members that fix the holding frame to the main frame from a first direction perpendicular to the adjustment direction of the mounting position by the position adjustment unit, and a plurality of second fixing members that fix the holding frame to the main frame from a second direction perpendicular to the adjustment direction, and the number of first fixing members and the number of second fixing members are the same. [Effects of the Invention]

[0006] According to the present invention, when a strong external force is applied to the image forming apparatus, it is possible to suppress the situation in which the mounting position of the retaining frame relative to the main body frame, which has been adjusted by the position adjustment unit, shifts. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram showing a color image forming apparatus according to an embodiment. [Figure 2] A perspective view showing the main frame. [Figure 3] Figure 2 shows the front support column at one end, viewed from the direction of arrow A1. [Figure 4] This diagram shows the front support column at the other end, viewed from the direction of arrow A2 in Figure 2. [Figure 5] Enlarged perspective view of the rear side panel. [Figure 6] Enlarged perspective view of region B1 in Figure 5. [Figure 7] Enlarged perspective view of area B2 in Figure 5. [Figure 8] Enlarged perspective view of area B3 in Figure 5. [Figure 9] Perspective view of the writing frame. [Figure 10] This is a view from the direction of arrow E in Figure 9. [Figure 11] An enlarged view seen from the C1 direction of FIG. 9. [Figure 12] An enlarged view seen from the direction of arrow C2 in FIG. 9. [Figure 13] An enlarged view of region D1 in FIG. 9. [Figure 14] An enlarged view of region D2 in FIG. 9. [Figure 15] An enlarged view of region D3 in FIG. 9. [Figure 16] An enlarged view of region D1 in the state where the writing frame is fixed to the rear side plate. [Figure 17] An enlarged view of region D2 in the state where the writing frame is fixed to the rear side plate. [Figure 18] An enlarged view of region D3 in the state where the writing frame is fixed to the rear side plate. [Figure 19] A perspective view showing the state where the writing frame is fixed to the main body frame. [Figure 20] (a) and (b) are perspective views of the position adjusting member constituting the position adjusting part in the embodiment, seen from the front and back respectively. [Figure 21] A view showing the periphery of the position adjusting member mounting hole in the state where the writing frame is positioned on the main body frame. [Figure 22] A view showing the periphery of the position adjusting member mounting hole in the state where the position adjusting member is attached. [Figure 23] A perspective view of the screw fastening portion at the attachment position of the writing frame to the front support on one end side of the main body frame, seen from the outside. [Figure 24] A perspective view of the same screw fastening portion, seen from the inside. [Figure 25] A front view showing the state where four process cartridges and a transfer device are positioned and fixed to the rear side plate. [Figure 26] The perspective view of FIG. 25 [Figure 27] A front view showing the state where the front side plate is positioned and fixed to the writing frame. [Figure 28] The perspective view of FIG. 27.

Mode for Carrying Out the Invention

[0008] Hereinafter, an embodiment in which the present invention is applied to a copying machine as an image forming apparatus will be described. First, the outline of the copying machine of this embodiment will be described using FIG. 1. The image forming apparatus of this embodiment has a function as a so-called digital color copier that scans and reads a document, digitizes it, and copies it onto paper. Further, this image forming apparatus also has a facsimile function for exchanging image information of a document with a remote location and a function of a so-called printer for printing image information handled by a computer onto paper.

[0009] In FIG. 1, the color image forming apparatus is a tandem type electrophotographic apparatus using an intermediate transfer belt 11, and a multi-stage paper feed unit 2 is provided at the bottom, an image forming unit 1 above it, and a scanner unit 3 further above it. Paper feed trays 21 as paper feed devices on which sheets (recording media) such as plain paper and OHP sheets are stacked are arranged on each stage of the paper feed unit 2.

[0010] At substantially the center of the image forming unit 1, a transfer device 10 having an endless intermediate transfer belt 11 is provided, and the intermediate transfer belt 11 rotates (moves on the surface) in the clockwise direction in the figure. Above the intermediate transfer belt 11, four process cartridges 40Y, 40M, 40C, 40K for yellow, magenta, cyan, and black are provided along the surface movement direction of the intermediate transfer belt 11 (hereinafter, the color separation symbols Y, M, C, K are appropriately omitted).

[0011] Each process cartridge 40 is provided with a drum-shaped photoreceptor 41 as a latent image carrier. Each photoreceptor 41 is rotatably provided in the counterclockwise direction in the figure, and a charging device 42, a developing device 43, a primary transfer device 46 constituting the primary transfer means, a photoreceptor cleaning device 44, and a lubricant application device 45 are provided around it, respectively. Further, two writing units 20a and 20b as latent image writing units are provided above the four process cartridges 40.

[0012] A secondary transfer device 22, which constitutes a secondary transfer means, is provided below the intermediate transfer belt 11. This secondary transfer device 22 is positioned to press against the secondary transfer opposing roller 16 via the intermediate transfer belt 11. The secondary transfer device 22 then transfers the toner image on the intermediate transfer belt 11 to the sheet that is fed between the intermediate transfer belt 11 and the secondary transfer device 22 in one go. Downstream of the secondary transfer opposing roller 16 in the direction of movement of the intermediate transfer belt surface, a transfer cleaning device 17 is provided. This transfer cleaning device 17 removes any residual toner remaining on the surface of the intermediate transfer belt 11 after image transfer. The transfer cleaning device 17 also includes a lubricant application mechanism, which applies lubricant to the surface of the intermediate transfer belt 11.

[0013] Downstream of the secondary transfer device 22 in the sheet transport direction, there is a fixing device 25 for fixing the toner image formed on the sheet to the sheet. The fixing device 25 is constructed by pressing pressure rollers 27 against an endless fixing belt 26. After image transfer, the sheet is transported to the fixing device 25 by an endless transport belt 24 stretched between a pair of rollers 23. Also, below the secondary transfer device 22, there is a sheet reversing device 28 for reversing the sheet when forming images on both the front and back surfaces of the sheet.

[0014] When making a color copy with the color image forming apparatus configured as described above, the scanner unit 3 reads the contents of the original document placed on the contact glass. The intermediate transfer belt 11 is rotated to form toner images on each photoreceptor 41 through a predetermined image forming process. Next, the toner images formed on each photoreceptor are sequentially superimposed and transferred to the intermediate transfer belt 11, forming a full-color toner image on the intermediate transfer belt 11.

[0015] Meanwhile, in parallel with the image formation operation of the full-color toner image on the intermediate transfer belt 11, sheets are sequentially separated and fed one by one from the selected paper tray 21 of the paper feeding unit 2 and transported to the registration roller 29. The sheets separated and fed as described above are temporarily stopped from being transported and put into a waiting position when they come into contact with the nip of the registration roller 29. The registration roller 29 is controlled to start rotating at a time that ensures the positional relationship between the full-color toner image formed on the intermediate transfer belt 11 and the leading edge of the sheet is at a predetermined position. This rotation of the registration roller 29 causes the waiting sheets to be fed again. As a result, the full-color toner image formed on the intermediate transfer belt 11 is transferred to the predetermined position on this sheet by the secondary transfer device 22.

[0016] The sheet onto which the full-color toner image has been transferred is then fed to the fixing device 25 downstream of the transport path. The fixing device 25 fixes the full-color toner image transferred by the secondary transfer device 22 onto the sheet. The sheet with the fixed full-color toner image is then discharged to the outside of the device by the paper discharge roller 30. When image formation is to be performed on both sides of the sheet, the front and back sides of the sheet are reversed by passing it through the sheet reversal device 28. The reversed sheet then abuts against the nip of the registration roller 29, and after its skew is corrected, image formation is performed on the back side in the same manner as when image formation is performed on one side as described above.

[0017] Next, the frame structure of the image forming apparatus, which is a characteristic feature of this embodiment, will be described. Figure 2 is a perspective view showing the main frame 100 that forms the skeleton of the image forming apparatus. As shown in Figure 2, the main frame 100 consists of a bottom plate 103, four support columns 101a, 101b, 102a, and 102b which form the side frame, a partition plate 106 that separates the paper feeding section 2 from the image forming section 1, and multiple horizontal stays 104a, 104b, 104c, 104d, 104e, and 104f.

[0018] The four support columns 101a, 101b, 102a, and 102b extend vertically (in the Z direction in the figure) from the four corners of the rectangular base plate 103. Three horizontal stays 104a, 104b, and 104c are attached between the front support column 101a and the rear support column 102a at one end in the Y direction (left side in Figure 2). Similarly, three horizontal stays 104d, 104e, and 104f are attached between the front support column 101b and the rear support column 102b at the other end in the Y direction (right side in Figure 2). In addition, the upper rear stay 105 is fixed to the rear support column 102a and the rear support column 102b at the other end.

[0019] A rear paper feed plate 107 is attached to the rear side of the bottom plate 103. A partition plate support stay 108 for supporting the partition plate 106 is also attached to the bottom plate 103. A mounting stay 109 for attaching the partition plate 106 is provided between the front support columns 101a and 101b.

[0020] The rear support columns 102a and 102b of the main frame 100 are screwed to the four corners of the rear side plate 110. By fixing the four corners of the rear side plate 110 to the rear support column 102a on one end of the main frame 100 and the rear support column 102b on the other end in this way, the rigidity of the main frame 100 can be increased. As a result, when a force in the Y direction is applied to the main frame 100, deformation of the main frame 100 into a parallelogram can be suppressed.

[0021] In this embodiment, the four corners of the rear plate 110 are screwed to the main frame 100. However, by fixing the rear plate 110 in two or more places in the Y direction and fixing it to the main frame 100 in one or more places at a position offset in the Z direction from the line connecting these Y-direction fixing points, the rigidity against forces in the Y direction can be increased. In addition, although the rear plate 110 is fixed to the main frame 100 with screws, for example, fitting holes may be provided in the rear plate 110 and fitting protrusions may be provided in the main frame 100 to fit and fix the rear plate 110 to the main frame 100, or it may be fixed by other methods.

[0022] Figure 3 is an enlarged view of the front support column 101a at one end of Figure 2, as seen from the direction of arrow A1 in Figure 2. As shown in Figure 3, the XZ plane (left side) of the front support column 101a at one end of the main frame 100 has two vertically elongated holes 121a at one end. Positioning claws of the writing frame, which will be described later, are inserted into these elongated holes 121a. In addition, the XZ plane (left side) of the front support column 101a at one end has a mounting hole 122 for a position adjustment member, which will be described later, and into which the position adjustment member is fitted.

[0023] Figure 4 is a view of the other end front support column 101b of Figure 2, as seen from the direction of arrow A2 in Figure 2. As shown in Figure 4, two elongated holes 121b are provided vertically on the XZ plane (right side) of the other end front support 101b. Positioning claws for the writing frame, which will be described later, are inserted into these other end elongated holes 121b.

[0024] The vertical length of the elongated hole 121a on one end of the front support column 101a shown in Figure 3 is longer than the elongated hole 121b on the other end of the front support column 101b shown in Figure 4.

[0025] Figure 5 is an enlarged perspective view of the rear side plate 110. Figure 6 is an enlarged perspective view of region B1 in Figure 5. Figure 7 is an enlarged perspective view of area B2 in Figure 5. Figure 8 is an enlarged perspective view of area B3 in Figure 5.

[0026] As shown in Figure 5, the rear plate 110 is provided with rear photoreceptor positioning holes 111Y, 111M, 111C, and 111K for positioning the rear sides of the photoreceptors 41Y, 41M, 41C, and 41K relative to the main body of the device. In addition, as shown in Figures 6 to 8, the rear plate 110 is provided with four writing frame positioning holes 113 for positioning the writing frame, which will be described later, on the rear plate 110. Furthermore, as shown in Figure 5, the rear plate 110 is provided with three rear transfer positioning holes 112 for positioning the transfer device 10.

[0027] Figure 9 is a perspective view of the writing frame 130, which serves as a holding frame for positioning and holding the two writing units 20a and 20b, and Figure 10 is a view from the direction of arrow E in Figure 9. As shown in Figures 9 and 10, the writing frame 130 includes a front writing stay 131, two horizontal writing stays 132a and 132b, a partition stay 133 separating the two writing units 20a and 20b, a frame bottom plate 134 separating the writing units 20a and 20b from the process cartridge 40, and support stays 135a and 135b for positioning and supporting the writing units 20a and 20b.

[0028] The frame base plate 134 is provided with four scanning light transmission holes 134a for directing scanning light from the respective writing units 20a and 20b onto the photoreceptors 41Y, 41M, 41C, and 41K. A front writing stay 131 is attached to the front end (rear side in Figure 9) of the frame base plate 134. Horizontal writing stays 132a and 132b are attached to one and the other end of the front writing stay 131 in the Y direction, and to one and the other end of the frame base plate 134 in the Y direction, respectively. A partition stay 133 is fixed to the center of the frame base plate 134 in the Y direction in the figure, and to the center of the front writing stay 131 in the Y direction. Two support stays 135a for positioning and supporting the writing unit 20a and two support stays 135b for positioning and supporting the writing unit 20b are also attached to the frame base plate 134.

[0029] Figure 11 is an enlarged view of Figure 9, seen from the C1 direction. As shown in Figure 11, two one-end positioning claws 131a are provided on one end in the Y direction of the front writing stay 131 of the writing frame 130. In addition, a supported hole 131c is provided into which a support projection of a position adjustment member, which will be described later, is inserted and which is supported by the support projection of the position adjustment member. The supported hole 131c has an elongated shape that extends in the X direction.

[0030] Figure 12 is an enlarged view from the direction of arrow C2 in Figure 9. As shown in Figure 12, two other-end positioning claws 131b are provided on the other end of the pre-writing stay 131 in the Y direction.

[0031] Figure 13 is an enlarged view of region D1 in Figure 9. Figure 14 is an enlarged view of region D2 in Figure 9. Figure 15 is an enlarged view of region D3 in Figure 9.

[0032] As shown in Figures 13 to 15, each support stay 135a and 135b is provided with a rear positioning claw 136 for positioning on the rear plate 110. Each support stay 135a and 135b is also provided with a rear fixing portion 137 having a screw hole 137a for screw fastening to the rear plate 110. Furthermore, as shown in Figure 14, the rear end of the partition stay 133 is also provided with a rear fixing portion 133a having a screw hole 133b for screw fastening to the rear plate 110.

[0033] Next, we will explain how to attach the writing frame 130 to the main frame 100. First, as shown in Figures 16 to 18, the rear positioning claws 136 of each support stay 135a and 135b shown in Figures 13 to 15 are inserted into the writing frame positioning holes 113 of the rear side plate 110 shown in Figures 6 to 8. This positions the writing frame 130 on the rear side plate 110. Then, screws 165 are screwed into the screw holes 137a of the rear fixing portion 137 of each support stay 135 from the rear side plate 110 side, thereby fixing each support stay 135 to the rear side plate 110. Note that the partition stay 133 is not shown in Figure 17.

[0034] Furthermore, the partition stay 133 is fixed to the rear side plate 110 by screwing a screw into the screw hole 133b of the rear fixing part 133a of the partition stay 133 from the rear side plate 110 side. In addition, the writing horizontal stays 132a, 132b and the rear end of the frame bottom plate 134 are also screwed to the rear side plate 110.

[0035] Figure 19 is a perspective view showing the writing frame 130 fixed to the main frame 100. The rear plate 110 is to which the support stays 135, partition stays 133, writing horizontal stays 132a and 132b, and the rear end of the frame bottom plate 134 are fixed. As a result, the rear plate 110 functions as a rear writing stay (having the same function as the front writing stay 131) of the writing frame 130. With this configuration, the number of parts can be reduced compared to a configuration in which the writing frame 130 has a separate rear writing stay from the rear plate 110, thereby suppressing increases in the cost and weight of the device.

[0036] Next, the one-end positioning claw 131a shown in Figure 11 is inserted into the one-end elongated hole 121a of the one-end front support 101a shown in Figure 3, and the other-end positioning claw 131b shown in Figure 12 is inserted into the other-end elongated hole 121b shown in Figure 4, thereby positioning the front side of the writing frame 130 on the front supports 101a and 101b of the main frame 100.

[0037] As shown in Figure 2 above, the upper part of the front support column 101a at one end and the upper part of the front support column 101b at the other end are not connected by a stay, so they can bend outward in the Y direction to a certain extent. This allows the positioning claws 131a and 131b of the writing frame 130, which protrude in the Y direction, to be inserted into the elongated holes 121a and 121b of the front supports 101a and 101b, respectively.

[0038] As shown in Figure 9 above, since the frame base plate 134 is long in the Y and X directions, the frame base plate 134 can twist or bend, making it easy for twisting and bending to occur in the writing frame 130. For example, if the flatness of the base plate 103 of the main frame 100 shown in Figure 2 is poor, and the height positions of the four support columns 101a, 101b, 102a, and 102b extending from the base plate 103 are inconsistent, twisting and bending will occur in the writing frame 130, which is positioned relative to these four support columns 101a, 101b, 102a, and 102b. When the writing frame 130 is fixed to the main frame 100 in this twisted or bent state, the flatness (horizontalness) of the support stays 135a and 135b that position and support the writing units 20a and 20b will deteriorate. As a result, the writing units 20a and 20b cannot be accurately positioned within the main body of the device.

[0039] To suppress such twisting and bending of the writing frame 130, one could, for example, increase the thickness of the frame base plate 134 to increase the rigidity of the writing frame 130, or improve the flatness of the base plate 103 of the main frame 100. However, in this case, material costs and manufacturing costs would increase, potentially leading to an increase in the cost of the device. In addition, the weight of the device would increase, potentially increasing the transportation costs of the image forming apparatus.

[0040] Therefore, in this embodiment, a position adjustment unit is provided to fix the writing frame 130 to the main frame in a state where such twisting and bending are eliminated. This position adjustment unit eliminates twisting and bending of the writing frame 130 by adjusting the mounting position of the writing frame 130 relative to the main frame 100 at some of the multiple locations where the writing frame 130 is positioned relative to the main frame 100. As a result, the flatness of the support stays 135a and 135b on the writing frame 130 is adjusted, so that the writing units 20a and 20b are positioned and supported on the device body in a horizontal state.

[0041] Figures 20(a) and (b) are perspective views of the position adjustment member 140, which constitutes the position adjustment section of this embodiment, as viewed from the front and back, respectively. As shown in Figure 20(b), the position adjustment member 140 is provided with a fitting portion 141 that fits into the position adjustment member mounting hole 122 shown in Figure 3. A cylindrical support projection 142 is provided at a location off-center from the axis of the fitting portion 141, so as to protrude axially from the fitting portion 141.

[0042] Furthermore, as shown in Figure 20(a), the position adjustment member 140 has screw insertion holes 143 extending along the circumferential direction, provided on the left and right sides of the position adjustment member 140 in the figure. In addition, the position adjustment member 140 has hooks 144 at two locations, top and bottom, in the figure, for rotating the position adjustment member 140 around its axis. To rotate the position adjustment member 140 around its axis, a tool such as needle-nose pliers is hooked onto these hooks 144 and the position adjustment member 140 is rotated around its axis.

[0043] The position adjustment member 140 can be made of resin, stainless steel, or the like, but in this embodiment, a resin one is used for ease of manufacturing.

[0044] The diameter of the fitting portion 141 is the same as or slightly smaller than the diameter of the mounting hole 122 for the position adjustment member shown in Figure 3. Furthermore, the diameter of the support projection 142 is approximately the same as the short-side length of the elongated hole-shaped supported hole 131c shown in Figure 11.

[0045] Figure 21 shows the area around the mounting hole 122 for the position adjustment member when the writing frame 130 is positioned on the main frame 100. Note that this positioning state is the state before the writing frame 130 is fixed to the main frame 100.

[0046] As shown in Figure 21, when the writing frame 130 is positioned on the main frame 100, the supported hole 131c is positioned to overlap with the mounting hole 122 of the position adjustment member. From this state, the support projection 142 of the position adjustment member 140 is inserted into the supported hole 131c, and the fitting portion 141 of the position adjustment member 140 is fitted into the mounting hole 122 of the position adjustment member. As a result, one end of the writing frame 130 in the Y direction on the front side is supported (placed) on the front support column 101a of the main frame 100 via the support projection 142. The position adjustment member 140 is fastened to the front support column 101a by inserting a screw into the screw insertion hole 143 of the position adjustment member 140 and screwing the screw into the front support column 101a.

[0047] Figure 22 shows the area around the mounting hole 122 for the position adjustment member 140 when it is installed. When adjusting the flatness (horizontalness) of the writing frame 130 with the position adjustment member 140, first, a measuring instrument for measuring horizontality is installed on the support stays 135a and 135b to which the writing units 20a and 20b are positioned and supported. Next, after loosening the screws 166 that fasten the position adjustment member 140, a tool such as needle-nose pliers is hooked onto the hook portion 144 and the position adjustment member 140 is rotated around its axis (around the Y axis). As the position adjustment member 140 rotates around its axis, the support projection 142, which is positioned eccentrically with respect to that axis, moves within the elongated hole 131c, displacing one end of the front side of the writing frame 130 in the Y direction vertically (in the Z direction).

[0048] At this time, as shown in Figure 21, the vertical length of the elongated hole 121a formed in the front support column 101a at one end of the main frame 100 is longer than the vertical length of the positioning claw 131a at one end of the writing frame 130. Therefore, even when the positioning claw 131a is inserted into the elongated hole 121a and positioned, the positioning claw 131a can be displaced vertically along the elongated hole 121a. Thus, when the position adjustment member 140 displaces the front Y-side of the writing frame 130 vertically (Z-direction), the positioning claw 131a is not restricted by the elongated hole 121a, and the writing frame 130 can be displaced vertically (Z-direction).

[0049] Then, while checking the horizontality with measuring instruments installed on support stays 135a and 135b, the position adjustment member 140 is rotated. Once the measuring instruments indicate horizontality, the rotation of the position adjustment member 140 is stopped, and the position adjustment member 140 is fastened to the front support column 101a on one end of the main frame 100 with a screw 166. This prevents the position adjustment member 140 from rotating and causing the flatness (horizontality) of the writing frame 130 to shift when the device is subjected to impact or other forces after adjustment.

[0050] Next, the writing frame 130 is screwed to the front support columns 101a and 101b. Specifically, the writing frame 130 is screwed to the front support columns 101a and 101b from the X direction. As a result, the writing frame 130 is sandwiched and fixed in the X direction by the rear plate 110 and the front support columns 101a and 101b, thereby suppressing vibration of the writing frame 130 relative to the main frame 100 in the X direction.

[0051] Furthermore, the writing frame 130 is screwed to the front support column 101a at one end and the front support column 101b at the other end from the Y direction, and also screwed to the rear support column 102a at one end and the rear support column 102b at the other end from the Y direction. As a result, even if an impact is applied in the Y direction, the writing frame 130 can be prevented from vibrating in the Y direction relative to the main frame 100.

[0052] In general, image forming apparatuses can be subjected to strong external forces due to large impacts during transport or use. When such strong external forces are applied, if the screw fastening force (fixing force) of the writing frame 130 to the front support column 101a at one end is insufficient, the mounting position of the writing frame 130 to the front support column 101a at one end may shift. More specifically, when strong external forces are applied, the mounting position of the writing frame 130 to the main frame 100 (front support column 101a at one end), which has been adjusted by the position adjustment member 140, may shift in the direction of adjustment by the position adjustment member 140 (Z direction).

[0053] Specifically, if the screw fastening force (fixing force) of the writing frame 130 to the front support column 101a at one end is insufficient, a strong external force may be applied that deforms the support projection 142 in the Z direction at the contact point between the support projection 142 of the position adjustment member 140 and the supported hole 131c of the writing frame 130. As a result, the position of the writing frame 130 moves relative to the front support column 101a at one end, while the support projection 142 is deformed in the Z direction. Consequently, the mounting position of the writing frame 130 on the main frame 100 (front support column 101a at one end), which has been adjusted by the position adjustment member 140, shifts in the direction of adjustment by the position adjustment member 140 (Z direction), causing a misalignment of the writing units 20a and 20b.

[0054] In particular, as in this embodiment, if the position adjustment member 140 is made of resin, the support projection 142 of the position adjustment member 140 is prone to deformation due to insufficient strength, and misalignment of the mounting position is likely to occur.

[0055] Furthermore, if at least one of the frames, the front support column 101a on one end of the main frame 100 and the writing frame 130, is made of electric furnace steel plate, it is difficult to obtain a high fixing force by screw fastening, making misalignment of the mounting position likely to occur. In other words, electric furnace steel plate is used for purposes such as increasing the rigidity of the main frame 100 and the writing frame 130 because of its high rigidity. However, because the surface of a frame made of electric furnace steel plate is hard, it is difficult to increase the static friction force between the contact surface (the surface that contacts by screw fastening) of the front support column 101a on one end of the main frame 100 and the writing frame 130. Therefore, it is difficult to ensure sufficient fixing force of the writing frame 130 to the front support column 101a by screw fastening.

[0056] To ensure sufficient fixing force of the writing frame 130 to the main frame 100 (front support column 101a at one end), increasing the number of screw fastening points (number of screws) is effective. However, in the limited space around the mounting position adjusted by the position adjustment member 140 (the contact position between the support projection 142 and the supported hole 131c), there is a limit to the number of screws that can be placed.

[0057] Figure 23 is an external perspective view of the screw fastening location at the mounting position of the writing frame 130 to the front support column 101a at one end of the main frame 100. Figure 24 is a perspective view from the inside of the screw fastening location at the mounting position of the writing frame 130 to the front support column 101a at one end of the main frame 100.

[0058] In this embodiment, the writing frame 130 is fixed to the front support column 101a at one end of the main frame 100 by screw fastening from two directions, the X direction (first direction) and the Y direction (second direction), which are perpendicular to the adjustment direction (Z direction) by the position adjustment member 140, as described above. Specifically, the writing frame 130 is fixed to the front support column 101a at one end from the X direction by first screws 167a to 167d, which are screw fastening members that serve as the first fixing member, and the writing frame 130 is also fixed to the front support column 101a at one end from the Y direction by second screws 168a to 168d, which are screw fastening members that serve as the second fixing member.

[0059] In this way, by fixing the writing frame 130 to the front support column 101a on one end using screws 167a-167d and 168a-168d from two directions, the X and Y directions, which are perpendicular to the adjustment direction (Z direction), the number of screws that can be placed in a limited space can be increased compared to fixing with screws from only one direction, thereby improving the fixing force.

[0060] However, even with a configuration that secures from two directions, the number of screws that can be placed in the limited space around the mounting position (the contact position between the support projection 142 and the supported hole 131c) is insufficient to ensure adequate fixing force, and the fixing force may be insufficient. Specifically, if the number of first screws 167a to 167d that secure from the X direction is different from the number of second screws 168a to 168d that secure from the Y direction, the fixing force from all of the limited number of screws will be biased towards either the X or Y direction. As a result, the fixing force from the direction with less fixing force (X or Y) will be insufficient, and when a strong external force occurs, it can cause the mounting position to shift.

[0061] Therefore, in this embodiment, as shown in Figures 23 and 24, the number of first screws 167a to 167d that fix from the X direction and the number of second screws 168a to 168d that fix from the Y direction are set to the same number (four of each). This allows the fixing force from the limited number of screws (eight) to be distributed with little bias to the X and Y directions, thus avoiding a situation where the fixing force from either the X or Y direction is insufficient. As a result, it is possible to suppress the situation in which the mounting position shifts when a strong external force occurs.

[0062] In particular, in this embodiment, the four first screws 167a to 167d that fix from the X direction are arranged in equal numbers in two regions (i.e., the region above and the region below the dashed line Ly in Figure 23) that are divided in the adjustment direction (Z direction) at the contact position (mounting position) between the support projection 142 and the supported hole 131c. That is, two of the four first screws 167a to 167d are arranged on the upper and lower sides of the contact position (mounting position) between the support projection 142 and the supported hole 131c.

[0063] According to this, the fixing force by the first screws 167a to 167d can be equalized between two regions that are divided in the adjustment direction (Z direction) with respect to the contact position (mounting position) between the support projection 142 and the supported hole 131c. Therefore, the occurrence of misalignment of the contact position between the support projection 142, which serves as the reference for the mounting position, and the supported hole 131c can be effectively suppressed.

[0064] Furthermore, in this embodiment, the four first screws 167a to 167d are positioned symmetrically with respect to the region division line Ly that passes through the contact position (mounting position) between the support projection 142 and the supported hole 131c, as shown in Figure 23. This allows the fixing force between the two regions to be equalized at each position along the region division line Ly, thereby further effectively suppressing the occurrence of misalignment of the contact position between the support projection 142, which serves as the reference for the mounting position, and the supported hole 131c.

[0065] Similarly, in this embodiment, the four second screws 168a to 168d that fix from the Y direction are also arranged in equal numbers in two regions (i.e., the region above and the region below the dashed line Lx in Figure 23) that are divided in the adjustment direction (Z direction) at the contact position (mounting position) between the support projection 142 and the supported hole 131c. In other words, the four second screws 168a to 168d are arranged two on the upper side and two on the lower side, flanking the contact position (mounting position) between the support projection 142 and the supported hole 131c.

[0066] According to this, the fixing force by the second screws 168a to 168d can be equalized between two regions that are divided in the adjustment direction (Z direction) with respect to the contact position (mounting position) between the support projection 142 and the supported hole 131c. Therefore, the occurrence of misalignment of the contact position between the support projection 142, which serves as the reference for the mounting position, and the supported hole 131c can be effectively suppressed.

[0067] Furthermore, in this embodiment, the four second screws 168a to 168d are also positioned symmetrically with respect to the region division line Lx that passes through the contact position (mounting position) between the support projection 142 and the supported hole 131c, as shown in Figure 23. This allows the fixing force between the two regions to be equalized at each position along the region division line Lx, thereby further effectively suppressing the occurrence of misalignment of the contact position between the support projection 142, which serves as the reference for the mounting position, and the supported hole 131c.

[0068] In this embodiment, we have described an example where there are four first screws 167a to 167d and four second screws 168a to 168d. However, as long as the number of first screws 167a to 167d and second screws 168a to 168d are the same, their numbers can be set arbitrarily, but it is preferable that there be an even number of four or more.

[0069] Furthermore, it is preferable that the first screws 167a to 167d and the second screws 168a to 168d have an outer diameter of 3.5 mm or more. This allows for a higher fixing force from a single screw compared to screws with an outer diameter of less than 3.5 mm, making it easier to secure sufficient fixing force with fewer screws.

[0070] Furthermore, it is preferable to place anti-loosening members such as washers at the screw fastening points of the first screws 167a to 167d and the second screws 168a to 168d. This suppresses loosening of the screws due to vibrations of the device, allowing the writing frame 130 to be fixed to the main frame 100 more stably.

[0071] Furthermore, in this embodiment, the fixing member for securing the writing frame 130 to the front support column 101a on one end was described as a screw fastening member consisting of first screws 167a to 167d and second screws 168a to 168d, but other fixing members may be used. For example, the frame may be fixed by welding instead of screws.

[0072] After fixing the writing frame 130 to the main frame 100 as described above, the photoreceptor shafts of the four process cartridges 40 are then inserted into the rear photoreceptor positioning holes 111 shown in Figure 5, thereby positioning each process cartridge 40 on the rear plate 110. Additionally, the rear transfer positioning projection of the transfer device 10 is inserted into the rear transfer positioning hole 112 of the rear plate 110, thereby positioning the transfer device 10 on the rear plate 110.

[0073] Figure 25 is a front view showing the four process cartridges 40 and the transfer device 10 positioned and fixed to the rear plate 110, and Figure 26 is a perspective view thereof. As shown in Figures 25 and 26, the front writing stay 131 of the writing frame 130 is provided with two front plate positioning protrusions 131e at predetermined intervals in the Y direction for positioning the front plate. The front writing stay 131 of the writing frame is also provided with two screw holes 131f for screwing the front plate in place. The transfer device 10 is also provided with three front transfer positioning protrusions 161.

[0074] Figure 27 is a front view showing the front plate 150 positioned and fixed to the writing frame 130, and Figure 28 is a perspective view thereof. As shown in Figure 27, the front plate 150 is provided with four front photoreceptor positioning holes 152Y, 152M, 152C, and 152K into which the front axis of each photoreceptor is positioned and inserted. In addition, there are three front transfer positioning holes 153 into which the front transfer positioning projections 161 of the transfer device 10 are inserted. The front axis of each photoreceptor is inserted into the four photoreceptor positioning holes 152Y, 152M, 152C, and 152K, respectively, and positioned. The photoreceptors (process cartridges) are positioned on the front plate 150 and the rear plate 110 within the main body of the device. Furthermore, the three front transfer positioning projections 161 of the transfer device 10 are inserted into the front transfer positioning holes 153 of the front plate 150, respectively, and the transfer device 10 is positioned on the front plate 150 and the rear plate 110. Once the process cartridge 40 and transfer device 10 are positioned on the front plate 150 and rear plate 110, the front plate 150 is fastened to the front writing stay 131 of the writing frame 130 with screws 163.

[0075] In this embodiment, the writing frame 130 is positioned and fixed directly to the rear plate 110 without going through the main frame 100. This eliminates the accumulation of mounting tolerances of the main frame, unlike when the rear plate 110 and the writing frame are each positioned and fixed to the main frame. This improves the positional accuracy between the writing frame 130 and the rear plate 110. Furthermore, since the front plate 150 is positioned and fixed directly to the writing frame 130, this eliminates the accumulation of mounting tolerances of the main frame, unlike when the front plate 150 and the writing frame 130 are each positioned and fixed to the main frame. This improves the positional accuracy between the writing frame 130 and the front plate 150. As a result, positional deviations between the two writing units 20a and 20b positioned and fixed to the writing frame 130 and the four photoreceptors 41Y, 41M, 41C, and 41K positioned and fixed to the rear plate 110 and the front plate 150 can be suppressed, thereby suppressing color misalignment. Furthermore, since the front and rear plates position the four photoreceptors, positional deviations between each photoreceptor can be suppressed. Also, since the front and rear plates that position the four photoreceptors position the transfer device 10, positional deviations between each photoreceptor and the intermediate transfer belt can be suppressed.

[0076] The above is just one example; each of the following embodiments produces its own unique effects. [First aspect] The first embodiment is an image forming apparatus comprising: a main frame 100 of the image forming apparatus; a holding frame (e.g., writing frame 130) for holding components constituting the image forming apparatus (e.g., writing units 20a, 20b); a position adjustment unit (e.g., position adjustment member 140) for adjusting the mounting position of the holding frame with respect to the main frame; and a fixing unit for fixing the holding frame to the main frame at the mounting position adjusted by the position adjustment unit, wherein the fixing unit includes a plurality of first fixing members (e.g., first screws 167a to 167d) for fixing the holding frame to the main frame from a first direction (e.g., X direction) perpendicular to the adjustment direction of the mounting position by the position adjustment unit (e.g., Z direction); and a plurality of second fixing members (e.g., second screws 168a to 168d) for fixing the holding frame to the main frame from a second direction (e.g., Y direction) perpendicular to the adjustment direction, and the number of first fixing members is the same as the number of second fixing members. Image forming apparatuses may be subjected to strong external forces due to significant impacts during transportation or use. When such strong external forces are applied, if the fixing force of the fixing part that secures the retaining frame to the main frame at the mounting position adjusted by the position adjustment unit is insufficient, the mounting position adjusted by the position adjustment unit may shift in the direction of the adjustment made by the position adjustment unit. To suppress such shifts in the mounting position, it is necessary to ensure sufficient fixing force at the fixing part. To ensure sufficient fixing force at the fixing point, it is effective to increase the number of fixing members that secure the retaining frame to the main frame. However, in the limited space around the mounting position adjusted by the position adjustment unit, there is a limit to the number of fixing members that can be placed. In this embodiment, the fixing section uses not only a plurality of first fixing members that fix the retaining frame to the main frame from a first direction perpendicular to the adjustment direction of the mounting position, but also a plurality of second fixing members that fix the retaining frame to the main frame from a second direction (a direction different from the first direction) perpendicular to the adjustment direction. By fixing the retaining frame to the main frame using fixing members from two directions, the first and second directions, the number of fixing members that can be placed in the limited space around the mounting position can be increased compared to when fixing with fixing members from only one direction, and the fixing force of the fixing section can be improved. However, even with a configuration that uses fixing members to secure the mounting from two directions, the number of fixing members that can be placed in the limited space around the mounting position is insufficient to ensure adequate fixing force at the mounting point, and the fixing force at the mounting point may be insufficient. Specifically, if the number of first fixing members that secure from the first direction differs from the number of second fixing members that secure from the second direction, the fixing force from the limited number of fixing members will be biased towards one of the two directions. As a result, the fixing force from the direction with less fixing force will be insufficient, and when a strong external force occurs, it can cause the mounting position to shift. Therefore, in this embodiment, the number of first fixing members that fix from the first direction and the number of second fixing members that fix from the second direction are set to be the same. This allows the fixing force from a limited number of fixing members to be distributed with minimal bias to the first and second directions, thus avoiding a situation where the fixing force from either the first or second direction is insufficient. Thus, it is possible to suppress the situation in which the mounting position shifts when a strong external force occurs.

[0077] [Second aspect] The second embodiment is characterized in that, in the first embodiment, the position adjustment unit adjusts the mounting position by displacing the retaining frame relative to the main frame by bringing a position adjustment member 140 attached to the main frame into contact with the retaining frame, and at least one of the first fixing member and the second fixing member (for example, first screws 167a to 167d and second screws 168a to 168d) is arranged in equal numbers in two regions that are divided in the adjustment direction by the contact position between the position adjustment member and the retaining frame (the contact position between the support projection 142 and the supported hole 131c). According to this, for at least one of the first and second fixing members, the fixing force provided by the fixing members positioned in two regions separated in the adjustment direction by the contact position between the position adjustment member and the retaining frame can be equalized between the two regions. Therefore, the occurrence of misalignment of the contact position between the position adjustment member, which serves as the reference for the mounting position, and the retaining frame can be effectively suppressed.

[0078] [Third aspect] The third embodiment is characterized in that, in the second embodiment, at least one of the fixing members is positioned symmetrically with respect to the dividing line between the two regions passing through the contact position. According to this, the fixing force between the two regions can be equalized at each position along the dividing line of the two regions, so that the occurrence of misalignment of the contact position between the position adjustment member, which serves as the reference for the mounting position, and the retaining frame can be suppressed even more effectively.

[0079] [Fourth aspect] The fourth embodiment is characterized in that, in the third embodiment, at least one of the fixing members is arranged in an even number of four or more units. According to this, an arrangement that is symmetrical with respect to the dividing line between the two regions can be easily realized.

[0080] [Fifth aspect] The fifth embodiment is characterized in that, in any of the first to fourth embodiments, the plurality of first fixing members and the plurality of second fixing members are composed of screw fastening members (for example, first screws 167a to 167d and second screws 168a to 168d). According to this method, the retaining frame can be fixed to the main frame using a simple method, thereby reducing manufacturing costs.

[0081] [Sixth aspect] The sixth aspect is an image forming apparatus according to the fifth aspect, characterized in that the screw fastening member has an outer diameter of 3.5 mm or more. According to this, the fixing force of a single screw fastening member can be increased compared to screw fastening members with an outer diameter of less than 3.5 mm, and sufficient fixing force can be ensured with fewer fastening members.

[0082] [Seventh aspect] The seventh embodiment is characterized in that, in the fifth or sixth embodiment, the screw fastening member has a loosening prevention member (e.g., a washer). According to this, loosening of screw fastening members due to vibrations of the device is suppressed, so the retaining frame can be fixed to the main frame more stably.

[0083] [8th aspect] The eighth aspect is characterized in that, in any of the fifth to seventh aspects, at least one of the main frame and the retaining frame is made of electric furnace steel plate. In some cases, at least one of the main frame and the retaining frame may be made of electric furnace steel plate for purposes such as increasing its rigidity. However, because the surface of a frame made of electric furnace steel plate is hard, it is difficult to increase the static friction force between the contact surfaces of the main frame and the retaining frame. Therefore, even if the contact pressure between the contact surfaces of the main frame and the retaining frame is increased by screw fastening members, the static friction force between the contact surfaces remains low, making it difficult to ensure sufficient fixing force by the screw fastening members. According to this embodiment, as described above, even with a limited number of fixing members, displacement of the mounting position when a strong external force occurs can be suppressed, so a frame formed from such electric furnace steel plate can be adopted.

[0084] [Ninth aspect] The ninth aspect is characterized in that, in any of the first to fourth aspects, the plurality of first fixing members and the plurality of second fixing members are fixed by welding. This allows the retaining frame to be more securely fixed to the main frame.

[0085] [Tenth aspect] The tenth embodiment is characterized in that, in any of the first to ninth embodiments, the main frame comprises two or more lateral frames extending in the vertical direction (e.g., front support columns 101a, 101b, rear support columns 102a, 102b, etc.), the position adjustment unit adjusts the mounting position of the retaining frame to one of the two or more lateral frames (e.g., one-end front support column 101a), and the retaining frame is fixed to a predetermined position on the remaining lateral frames of the two or more lateral frames. According to this, the retaining frame can be fixed to the main frame while eliminating any twisting or bending of the retaining frame. [Explanation of Symbols]

[0086] 1: Image forming unit 2:Paper feed section 3: Scanner section 10: Transfer device 11: Intermediate transfer belt 16: Secondary transfer opposing roller 17: Transfer cleaning device 20a, 20b: Writing Unit 21: Paper feed tray 22: Secondary transfer device 24: Conveyor belt 25: Fixing device 28: Sheet reversing device 29: Registroller 40: Process cartridge 41: Photoreceptor 42: Charging device 43: Developing equipment 44: Photoconductor cleaning device 45: Lubricant application device 46: Primary transfer device 100: Main frame 101a, 101b: Front pillar 102a, 102b: Rear strut 103: Bottom plate 104a~104f: Horizontal stays 105: Upper rear stay 106: Partition plate 107: Paper feed section rear side plate 108: Partition plate support stay 109: Mounting bracket 110: Rear side plate 111: Rear photoreceptor positioning hole 112: Positioning hole for rear transfer 113: Writing frame positioning hole 121a: One end side long hole 121b:Other end side long hole 122: Mounting hole for position adjustment member 130: Write frame 131: Previously written stay 131a, 131b: Positioning claws 131c: Supported hole 131e: Positioning projection for front side plate 132a, 132b: Writing horizontal stay 133: Partition Stay 134: Frame base plate 135a, 135b: Support stays 136: Rear positioning claw 137: Rear fixed part 140: Position adjustment member 141: Fitting part 142: Support protrusion 143: Screw insertion hole 144: Hook part 150: Front side panel 152: Photoreceptor positioning hole 153: Front transfer positioning hole 161: Front transfer positioning projection 167a~167d: First Screw 168a~168d: Second screw [Prior art documents] [Patent Documents]

[0087] [Patent Document 1] Patent No. 6037203

Claims

1. The main frame of the image forming apparatus, A retaining frame that holds the components constituting the image forming apparatus, A position adjustment unit for adjusting the mounting position of the retaining frame to the main frame, An image forming apparatus having a fixing part that fixes the retaining frame to the main body frame at an attachment position adjusted by the position adjustment part, The fixing portion includes a plurality of first fixing members that fix the retaining frame to the main body frame from a first direction perpendicular to the adjustment direction of the mounting position by the position adjustment portion, and a plurality of second fixing members that fix the retaining frame to the main body frame from a second direction perpendicular to the adjustment direction. An image forming apparatus characterized in that the number of first fixing members and the number of second fixing members are the same.

2. In the image forming apparatus according to claim 1, The position adjustment unit adjusts the mounting position by displacing the retaining frame relative to the main frame by bringing a position adjustment member attached to the main frame into contact with the retaining frame. An image forming apparatus characterized in that at least one of the first fixing member and the second fixing member is arranged in equal numbers in two regions that are divided in the adjustment direction at the contact position between the position adjustment member and the holding frame.

3. In the image forming apparatus according to claim 2, The image forming apparatus is characterized in that at least one of the fixing members is positioned symmetrically with respect to the dividing line between the two regions passing through the contact position.

4. In the image forming apparatus according to claim 3, The image forming apparatus is characterized in that at least one of the fixing members is arranged in an even number of four or more units.

5. In the image forming apparatus according to any one of claims 1 to 4, An image forming apparatus characterized in that the plurality of first fixing members and the plurality of second fixing members are made of screw fastening members.

6. In the image forming apparatus according to claim 5, The image forming apparatus is characterized in that the screw fastening member has an outer diameter of 3.5 mm or more.

7. In the image forming apparatus according to claim 5, An image forming apparatus characterized by having a member to prevent loosening of the screw fastening member.

8. In the image forming apparatus according to claim 5, An image forming apparatus characterized in that at least one of the main frame and the holding frame is made of electric furnace steel plate.

9. In the image forming apparatus according to any one of claims 1 to 4, An image forming apparatus characterized in that the plurality of first fixing members and the plurality of second fixing members are fixed by welding.

10. In the image forming apparatus according to any one of claims 1 to 4, The main frame comprises two or more lateral frames extending in the vertical direction. The position adjustment unit adjusts the mounting position of the retaining frame to one of the two or more lateral frames, The image forming apparatus is characterized in that the holding frame is fixed to a predetermined position on the remaining lateral frame among the two or more lateral frames.

Images