Image forming apparatus

Abstract

The present invention provides an image forming apparatus capable of positioning a fixing unit with high precision and ensuring good attachability and detachability of the fixing unit with a small number of parts. One of a rotary fixing member (81) or a rotary pressure member (82) of a fixing unit (8) has an inner side end portion in a unit insertion direction connected to a driven gear (84). The driven gear (84) is engaged with a driving gear (14) provided on a main body of the image forming apparatus. A driving force (F) transmitted from a tooth surface of the driving gear (14) to a tooth surface of the driven gear (84) at an engagement position of the driving gear (14) and the driven gear (84) has a component that presses the fixing unit (8) toward a pair of supports (121, 122) in a horizontal direction. The fixing unit (8) is pressed by the pair of supports (121, 122) using the driving force in a state of being accommodated in a fixing unit accommodating portion (2e), and is thereby positioned in a direction perpendicular to the insertion direction.

Description

Technical Field

[0001] This invention relates to an image forming apparatus. Background Technology

[0002] Typically, electrophotographic image forming apparatuses include a fixing unit that uses a fixing roller and a pressure roller rotating in pressure contact with each other to fix a toner image onto a film. In this fixing unit, as the film passes through a gap formed between the fixing roller and the pressure roller, the toner image on the film is heated and pressurized before being fixed onto the film.

[0003] The fixing unit typically has a housing that houses the fixing roller and the pressure roller. The housing is detachably mounted to the main body of the image forming apparatus. Patent Document 1 discloses an example of a mounting and disassembling structure for the fixing unit relative to the main body of the image forming apparatus.

[0004] In the image forming apparatus, the mounting and dismounting direction of the fixing unit is set to be perpendicular to the long side direction of the housing (the axis direction of the fixing roller). Engaging pins protrude from both sides of the long side direction of the housing. A pushing member is provided in the main body of the image forming apparatus. When the fixing unit is installed into the main body, the pushing member engages with the engaging pins and, using the force of the force-applying member, pushes the fixing unit toward the mounting direction relative to the main body of the image forming apparatus. The pushing member is configured to rotate about a predetermined axis, and by operating the operating handle, the engagement between the pushing member and the engaging pins is released.

[0005] Existing technical documents

[0006] Patent Document 1: Japanese Patent Publication No. 2013-072987

[0007] As shown in Patent Document 1, in existing positioning structures where a locking pin on the fixing unit engages with a locking groove on the image forming apparatus body, the diameter of the locking groove relative to the locking pin needs to be increased to ensure the assembly and disassembly of the fixing unit. However, when the diameter of the locking groove relative to the locking pin is increased, the positioning accuracy of the fixing unit decreases.

[0008] Furthermore, in the existing positioning structure, the force-applying mechanism (force-applying member, etc.) for fixing the fixing unit to the main body of the image forming apparatus and the release mechanism (operating handle, etc.) for releasing the fixing need to be set separately. Therefore, the cost increases due to the increase in the number of parts. Summary of the Invention

[0009] In view of the above problems, the purpose of the present invention is to achieve high-precision positioning of the fixing unit with fewer parts and to ensure good assembly and disassembly of the fixing unit.

[0010] The image forming apparatus of the present invention includes an image forming apparatus body, the image forming apparatus body comprising: a fixing unit, wherein a toner image is fixed on the sheet body by passing the sheet body carrying the toner image through a slit formed by the pressure contact between the rotating fixing member and the rotating pressing member; and a fixing unit receiving portion, wherein the fixing unit is removably and insertably received.

[0011] Furthermore, the insertion / removal direction of the fixing unit relative to the fixing unit receiving portion is aligned with the axial direction of the rotary pressure member. The skeletal frame of the image forming apparatus includes: a pair of pillars, disposed adjacent to the fixing unit receiving portion and spaced apart in the insertion / removal direction of the fixing unit; and a pair of crossbeams, respectively connected at right angles to the pair of pillars when viewed from the insertion / removal direction, supporting the lower surface of the fixing unit. The image forming apparatus further includes: a driven gear, rotatably integrally connected to the inner end of one of the rotary fixing member or the rotary pressure member of the fixing unit in the insertion / removal direction; and a drive gear, disposed in the fixing unit. The inner end of the fixing unit receiving portion in the insertion / removal direction engages with the driven gear when the fixing unit is received in the fixing unit receiving portion; and a drive source that drives the drive gear to rotate, wherein the drive gear and the driven gear transmit power from the tooth surface of the drive gear to the tooth surface of the driven gear in their meshing position when transmitting power, having a component that presses the fixing unit toward the pair of pillars in the horizontal direction, wherein the fixing unit, in the state of being received in the fixing unit receiving portion, is pushed by the pair of pillars by the transmission force and positioned in a direction perpendicular to the insertion / removal direction.

[0012] According to the present invention, the fixing unit can be positioned with high precision with fewer parts and good assembly and disassembly of the fixing unit can be guaranteed. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the image forming apparatus in the embodiment.

[0014] Figure 2 This is a perspective view of the right end of the main frame, viewed from the oblique front right side, showing the state in which the fixing unit is installed in the fixing unit housing.

[0015] Figure 3 This is a front view of the right end of the main frame, showing the state in which the fixing unit is installed in the fixing unit housing.

[0016] Figure 4 This is a front view of the right end of the main frame, showing the state in which the fixing unit is removed from the fixing unit housing.

[0017] Figure 5 This is the front view of the discharge unit.

[0018] Figure 6 It is a cross-sectional view of the central part of the fixing unit cut by a vertical plane along the left and right direction.

[0019] Figure 7 This is a stereoscopic view of the fixing unit viewed from the right side at the front.

[0020] Figure 8 This is a stereoscopic view of the fixing unit viewed from the lower right angle.

[0021] Figure 9 This is a rear view of the right end of the main frame, viewed from the rear. The figure uses imaginary lines to represent part of the drive unit that drives the fixing unit, and solid lines to represent the drive gear.

[0022] Figure 10 It is an enlarged view showing the periphery of the meshing position between the drive gear and the pressure roller gear.

[0023] Figure 11 yes Figure 2 The cross-sectional view of the XI-XI line in the diagram.

[0024] Figure 12 It is a cross-sectional view showing the cross-sectional shape of the supports and beams that make up the protruding frame.

[0025] Figure 13 This indicates that the equivalent of variation 1 is... Figure 9 The image.

[0026] Figure 14 This indicates that variation 2 is equivalent to Figure 9 The image. Detailed Implementation

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0028] (Implementation Method)

[0029] Figure 1 A simplified structure of the image forming apparatus 1 in the embodiment is shown. In the following description, front side and rear side refer to the front side and rear side of the image forming apparatus 1, respectively. Figure 1 The left and right sides represent the left and right sides when viewing the image forming device 1 from the front (the side in front of the paper, perpendicular to the paper).

[0030] (Overall configuration of image forming apparatus 1)

[0031] The image forming apparatus 1 is a paper-ejecting copier, comprising an image forming apparatus body 2 and an image reading device 3 disposed on the upper side of the image forming apparatus body 2. The image reading device 3 generates image data by optically reading the original image.

[0032] The image forming apparatus body 2 is provided with an image forming section 4, which forms an image on paper P (an example of a sheet) based on the image data of the original document read by the image reading device 3. A transfer unit 6 is arranged above the image forming section 4. The transfer unit 6 has an annular intermediate transfer belt 6a extending in the left-right direction, and four primary transfer rollers 6b arranged side by side in the left-right direction inside the intermediate transfer belt 6a.

[0033] Below the image forming unit 4 is an exposure device 5 for irradiating with a laser. Below the exposure device 5 is a paper feeding unit 7 for storing paper P. Above the right side of the transfer unit 6 is a fixing unit 8 for fixing the image transferred onto the paper P. An internal paper output space S is provided between the image forming apparatus main body 2 and the image reading device 3, and the paper P that has undergone fixing treatment by the fixing unit 8 is discharged into the internal paper output space S.

[0034] The upper surface of the image forming apparatus body 2 has an output tray 9 for receiving paper P discharged into the internal paper output space S. The image forming apparatus body 2 has a paper feeding channel T extending from the paper supply section 7 toward the output tray 9. Below the fixing unit 8 in the paper feeding channel T, a secondary transfer roller 10 is provided, which is opposite to its drive roller 6c across an intermediate transfer belt 6a. Above the fixing unit 8 in the paper feeding channel T, an output roller pair 11 is provided to discharge paper P approximately horizontally toward the output tray 9.

[0035] A rectangular opening 2a is formed on the right side of the image forming apparatus body 2 adjacent to the paper feed channel T. The opening 2a can be opened and closed by an opening / closing cover 2b. The opening / closing cover 2b is supported in a manner that allows it to rotate relative to a support shaft 2f extending along the lower edge of the opening 2a. The opening / closing cover 2b is opened by rotating to the right from its closed state with the support shaft 2f as a fulcrum. By opening the opening / closing cover 2b, paper jams that obstruct the paper feed channel T can be cleared.

[0036] The image forming unit 4 includes a drum unit 20 and a developing unit 30, each configured for yellow, magenta, cyan, and black. The drum unit 20 has a rotatable photosensitive drum 21. An electrostatic latent image is formed on the surface of the photosensitive drum 21 by irradiating it with a laser based on predetermined image data by the exposure device 5.

[0037] The developing unit 30 includes a developing container 31 and a developing roller 32. Each developing container 31 contains developer, i.e., toner, supplied from a corresponding toner container (not shown). The developing roller 32 protrudes from the upper right side wall of the developing container 31 and rotates. The developing roller 32 causes toner to fly onto the surface of the photosensitive drum 21 by creating a potential difference between itself and the surface of the photosensitive drum 21. The electrostatic latent image on the surface of the photosensitive drum 21 is developed and visualized using the toner flying from the developing roller 32.

[0038] The toner images of each photosensitive drum 21, visualized by the developing unit 30, are sequentially transferred and overlapped onto the intermediate transfer belt 6a by a primary transfer roller 6b positioned above each photosensitive drum 21 under a bias applied pressure. The overlapped toner images are then transferred onto the paper P supplied from the paper feed unit 7 as it passes between the intermediate transfer belt 6a and the secondary transfer roller 10. The paper P with the transferred toner images is then fed to the fixing unit 8.

[0039] The fixing unit 8 has a fixing roller 81 and a pressure roller 82 that are opposed to each other in the left-right direction across the paper feed channel T. The fixing unit 8 uses the fixing roller 81 and the pressure roller 82 to clamp and feed a paper P carrying a toner image. The toner image on the paper P is heated and pressurized as it passes between the fixing roller 81 and the pressure roller 82, and is heat-fixed on the paper P. After the toner image has been heat-fixed, the paper P is discharged to the paper output tray 9 by the output roller pair 11 arranged on the upper side of the fixing unit 8.

[0040] (The containment structure of fixing unit 8)

[0041] Next, the housing structure of the fixing unit 8 of the relative image forming apparatus body 2 will be explained.

[0042] The image forming apparatus body 2 has a main frame 12 composed of multiple metal pillars and beams (see reference). Figure 2 (etc.), and encapsulation covers (not shown) covering each side of the main frame 12. The plurality of pillars and beams are, for example, constructed of hollow tubes with generally square cross sections.

[0043] On the upper right part of the encapsulation cover covering the front side of the main frame 12, there is an openable maintenance door 13 (only). Figure 1 (As shown). Opposite to the inner side of the maintenance door 13, there is a fixing unit receiving section 2e that can be easily inserted and removed to receive the fixing unit 8. The fixing unit receiving section 2e is composed of a hollow space extending in the front-back direction, and its front end (one side end) is provided with an insertion and removal opening 2g for inserting and removing the fixing unit 8.

[0044] (Specific composition of the fixing unit containment section 2e)

[0045] Reference Figures 2-4The fixing unit housing 2e is described in detail. The sealing cover and maintenance door 13 are omitted in the figures. Figure 2 This is a perspective view showing the state in which the fixing unit 8 is installed in the fixing unit housing 2e. Figure 3 This is the main view representing the state. Figure 4 This is a front view showing the state in which the fixing unit 8 has been removed from the fixing unit housing section 2e.

[0046] The fixing unit receiving part 2e is located in the lower part of the inner space K of the protruding frame part 120, which is mounted on the main frame 12. The protruding frame part 120 is adjacent to the right side of the paper output space S inside the body and is arranged across the entire front-rear direction of the main frame 12. The protruding frame part 120 and the frame components form a cuboid shape.

[0047] Specifically, the protruding frame portion 120, viewed from above, has a front right pillar 121, a rear right pillar 122, a front left pillar 123, and a rear left pillar 124 disposed at its four corners. The front right pillar 121 and the rear right pillar 122 are adjacent to the fixing unit receiving portion 2e and located to the right of the fixing unit receiving portion 2e, and are spaced apart in the front-back direction. Furthermore, the front left pillar 123 and the rear left pillar 124 are adjacent to the fixing unit receiving portion 2e and located to the left of the fixing unit receiving portion 2e, and are spaced apart side-by-side in the front-back direction. The front right pillar 121 and the rear right pillar 122 function as a pair of pillars for positioning the fixing unit 8 in the left-right direction.

[0048] The front right column 121 and the front left column 123 are connected by a lower connecting beam 125 and an upper connecting beam 126 extending in the left-right direction. The front right column 121, the front left column 123, the lower connecting beam 125, and the upper connecting beam 126 cooperate to form a rectangular frame extending in the vertical direction. Furthermore, the inner side of this rectangular frame forms an insertion port 2g for inserting the fixing unit 8 into the fixing unit receiving portion 2e. Additionally, the insertion port 2g also serves as the insertion / removal port for the ejection unit 40. The fixing unit 8 can be inserted and removed from the fixing unit receiving portion 2e via the insertion port 2g. The insertion / removal direction of the fixing unit 8 is consistent with the front-rear direction of the image forming apparatus 1.

[0049] The rear right column 122 and the rear left column 124 are connected by a lower connecting beam 127 and an upper connecting beam 128 extending in the left-right direction. The rear right column 122, the rear left column 124, the lower connecting beam 127, and the upper connecting beam 128 cooperate to form a rectangular frame extending in the vertical direction. A drive unit 100 (see reference) for driving the pressure roller 82 of the fixing unit 8 to rotate is disposed inside the rectangular frame. Figure 9 (Double-dotted lines). The upper front connecting beam 126 and the upper rear connecting beam 128 in the protruding frame 120 are connected by the front and rear beams 130 extending in the front-rear direction (see reference). Figure 2 )connect.

[0050] Furthermore, the inner space K of the protruding frame portion 120 houses the discharge unit 40, which includes the output roller pair 11. The fixing unit housing portion 2e is formed by the lower space below the output roller pair 11 in the inner space K.

[0051] (Composition of discharge unit 40)

[0052] like Figure 5 As shown, the discharge unit 40 has a paper output roller pair 11 and a support frame 41 supporting the paper output roller pair 11. The support frame 41 includes: a pair of opposing plates 41a supporting the two axial ends of the paper output roller pair 11; a vertical plate 41b connecting the left end of the pair of opposing plates 41a and extending in the vertical direction; and a horizontal protruding plate 41c protruding horizontally to the right from the lower end of the vertical plate 41b. The upper surface of the horizontal protruding plate 41c supports an IH heating unit 50 for heating the fixing roller 81. An opening 41d is formed on the vertical plate 41b through which the IH heating unit 50 passes. The right end edge of the horizontal protruding plate 41c supports the left end edge of the lower surface of the fixing unit 8, and during the insertion and removal operation of the fixing unit 8, the left end edge of the lower surface of the fixing unit 8 can slide in the back-and-forth direction on the right end edge of the horizontal protruding plate 41c.

[0053] (Composition of fixing unit 8 and IH heating unit 50)

[0054] Figure 6 This is a longitudinal cross-sectional view of the central portion of the fixing unit 8 and the IH heating unit 50 in the front-rear direction. As described above, the fixing unit 8 includes a fixing roller 81, a pressure roller 82, and a fixing cover 83.

[0055] The fixing roller 81 and the pressure roller 82 are generally cylindrical in shape, elongated in the front-to-back direction. The fixing roller 81 has an elastic layer 81b laminated on the outer peripheral surface of a metal mandrel 81a, and a fixing belt 81c covering the outer peripheral surface of the elastic layer 81b. The pressure roller 82 has an elastic layer 82b laminated on the outer peripheral surface of the mandrel 82a, and a release layer 82c covering the outer peripheral surface of the elastic layer 82b.

[0056] The fuser housing 83 is generally rectangular in shape, elongated in the front-to-back direction. A paper inlet 83c is formed on the lower surface of the fuser housing 83 for receiving paper P fed from the upstream side of the paper feed channel T. An outlet 83d is formed on the upper surface of the fuser housing 83 for discharging paper P after it has passed through the fuser roller 81 and the pressure roller 82. A rectangular opening 83b extending in the left-to-right direction is formed on the left side wall of the fuser housing 83, through which the left half of the fuser roller 81 protrudes to the outside of the fuser housing 83.

[0057] The IH heating unit 50 is disposed on the side opposite to the N side of the slit portion (left side) across the fixing roller 81. The IH heating unit 50 includes: a semi-cylindrical support frame 50a that opens towards the fixing roller 81; a plurality of IH coils 50b supported by the support frame 50a; and an arched magnetic core 50c formed of a strong magnetic material such as ferrite and covering the IH coils 50b. A semi-cylindrical recess 50g is formed on the inner surface of the support frame 50a. When the IH heating unit 50 is in the heating position, the surface portion of the fixing roller 81 opposite to the N side of the slit portion enters the recess 50g. Both the support frame 50a and the arched magnetic core 50c are disposed opposite to the fixing roller 81 and extend across its entire front-to-back direction.

[0058] (The action of fixing unit 8)

[0059] During the fixing process, the pressure roller 82 receives driving force from the drive unit 100 (described later) and rotates about its axis. The fixing roller 81 rotates about its axis in response to the pressure roller 82. Each IH coil 50b receives power from a power source (not shown) to generate a high-frequency magnetic field and heats the fixing belt 81c. The fixing roller 81 heats the toner image on the paper P passing through the slit section N while rotating. The pressure roller 82 applies pressure to the paper P passing through the slit section N while rotating. In this way, the toner image is fixed on the paper P.

[0060] (Specific composition of the fixing cover 83)

[0061] like Figure 7 and Figure 8 As shown, a recessed handle portion 83a is formed on the front side of the fuser housing 83. The installer can slide the fuser housing 83 back and forth by hooking the handle portion 83a with their fingers to insert or remove the fuser unit 8 from the fuser unit receiving portion 2e.

[0062] like Figure 2 As shown, with the fixing unit 8 housed in the fixing unit housing section 2e (installed state), the front end of the fixing cover 83 is supported from below by the front lower connecting beam 125, and the rear end of the fixing cover 83 is supported from below by the rear lower connecting beam 127. The left end edge of the fixing unit 8 is supported by the horizontal protrusion 41c of the discharge unit 40 (only). Figure 5 (Display) support.

[0063] The left-right position (perpendicular to the insertion / removal direction) of the fuser housing 83 is determined by its right side abutting against the front right post 121 and the rear right post 122. Specifically, two elongated rectangular abutment portions 83e protrude from the front-back ends of the right side of the fuser housing 83. The protruding end faces of the abutment portions 83e have a higher surface roughness and flatness than other parts of the right side of the fuser housing 83. Furthermore, the fuser housing 83 is positioned in the left-right direction by abutting against the front right post 121 and the rear right post 122 with the front and rear abutment portions 83e, respectively.

[0064] like Figure 8 As shown, a front supported portion 83f, supported by a front lower connecting beam 125, is formed on the front end of the lower surface of the fuser housing 83. The front supported portion 83f is composed of a plurality of reinforcing ribs 83h arranged at intervals in the left-right direction. A rear supported portion 83g, supported by a rear connecting beam 127, is formed on the rear end of the lower surface of the fuser housing 83. The rear supported portion 83g is composed of a plurality of reinforcing ribs 83i arranged at intervals in the left-right direction. By using a plurality of reinforcing ribs 83h and 83i to form each supported portion 83f and 83g respectively, the frictional force generated between the front connecting beam 125 and the rear connecting beam 127 and the fuser housing 83 during the insertion and removal of the fuser housing 83 can be reduced.

[0065] A front insertion limiting part 83j is provided on the portion of the fuser housing 83 adjacent to the front side of the front supported portion 83f. The front insertion limiting part 83j is formed by the lower end of the front sidewall of the fuser housing 83 and protrudes downward from the lower end edge of each reinforcing rib 83h. In addition, a rear insertion limiting part 83k is formed on the portion of the fuser housing 83 adjacent to the front side of the rear supported portion 83g, which protrudes further downward from the lower end edge of each reinforcing rib 83i. When the fuser unit 8 is inserted into the fuser unit receiving portion 2e, the front insertion limiting part 83j and the rear insertion limiting part 83k abut against the lower connecting beam 125 on the front side and the lower connecting beam 127 on the rear side, respectively, to limit the excessive pushing (insertion) of the fuser unit 8 and restrict the fuser unit 8 to a predetermined front-rear position. With the fixing unit 8 confined to a predetermined front-rear position, the rear end of the fixing unit 8 is connected to the drive unit 100 (see reference 100) in a power-transmitting manner. Figure 9 Connect the two dots and dashes.

[0066] (Composition of the drive unit 100)

[0067] Reference Figure 9The drive unit 100 includes: a flat outer cover member 101 in the front-rear direction; a drive gear 14 supported by a shaft portion 102 protruding from the front sidewall of the outer cover member 101 to the front side; a drive gear set (not shown) housed in the outer cover member 101; and a motor (not shown) that drives the drive gear 14 to rotate by means of the drive gear set.

[0068] By housing the fixing unit 8 in the fixing unit housing section 2e, the drive gear 14 meshes with the pressure roller gear 84 (an example of a driven gear). The pressure roller gear 84 is rotatably and integrally fixed on the spindle 82a of the pressure roller 82.

[0069] Figure 10 This is a schematic diagram showing the meshing state of the drive gear 14 and the pressure roller gear 84 as viewed from the axial direction. The straight line shown by the double-dotted line in the figure is the common tangent line of the meshing position M of the tooth surface 14a of the drive gear 14 and the tooth surface 84a of the pressure roller gear 84. The solid arrow represents the transmission force F transmitted from the tooth surface 14a of the drive gear 14 to the tooth surface 84a of the pressure roller gear 84 in the normal direction of the common tangent line.

[0070] The power transmission F is directed towards the lower right ( Figure 9 and Figure 10 The left side of the plane and the side where the front right column 121 and the rear right column 122 are located are inclined. Therefore, the transmission force F has: a horizontal component Fh that pushes the fixing unit 8 to the front right column 121 and the rear right column 122 in the horizontal direction; and a vertical component (vertically downward force component) Fv that pushes the fixing unit 8 to the lower connecting beam 125 and the lower connecting beam 127. Figure 9 and Figure 10 In the example, the horizontal component Fh and the vertical component Fv of the transmission force F are equal.

[0071] The extension line of the transmission force F passes through the intersection point C of the vertical plane A and the horizontal plane B, and is positioned vertically upwards at a predetermined distance δ. The vertical plane A includes the surface of the fixing unit housing 2e side of the front right column 121 and the rear right column 122, and the horizontal plane B includes the upper surfaces of the front and rear lower connecting beams 125 and 127. The predetermined distance δ is, for example, set to be more than 1 / 6 and less than 1 / 5 of the height of the fixing cover 83.

[0072] Furthermore, the fixing unit 8 is positioned by being pressed by the front right column 121 and the rear right column 122 using the horizontal component Fh of the power transmission F from the drive gear 14 to the pressure roller gear 84.

[0073] (Description of location status)

[0074] Figure 11This is a top view showing the state in which the fixing unit 8 is pressed by the front right column 121 and the rear right column 122. As shown in the figure, the fixing unit 8 is positioned in the left-right direction by the front and rear abutting seats 83e of the fixing cover 83 abutting against the front right column 121 and the rear right column 122 from the left side, respectively.

[0075] The front right pillar 121 and the rear right pillar 122 form line contact rather than surface contact with the front and rear abutment portions 83e, respectively. That is, the front right pillar 121 and the rear right pillar 122... Figure 12 As shown, when viewed in a cross-section perpendicular to the column length, the four corners W form an arc shape, and the central part of each side in the width direction has an arched recess V. Furthermore, at both ends of each recess V of each right column 121, 122 (the boundary positions of the arc shape between the recess V and the corner W), ridge lines R extending in the column length direction are formed. Therefore, when the fixing unit 8 is pressed by the front right column 121 and the rear right column 122, since the ridge lines R of each right column 121, 122 are in line contact with the fixing cover 83, the fixing unit 8 can be positioned with high precision compared to surface contact.

[0076] Furthermore, in this embodiment, all the pillars and beams constituting the main frame 12 can be made of square tubes with the same cross-sectional shape as the front right column 121 and the rear right column 122. Therefore, for example, through the lower front connecting beam 125 (see reference...) Figure 2 The lower connecting beam 127 on the rear side can also improve the positioning accuracy of the fixing unit 8 in the vertical direction.

[0077] (Effects of this implementation method)

[0078] As described above, in this embodiment, the insertion / removal direction (front-to-back direction) of the fixing unit 8 relative to the fixing unit receiving portion 2e is aligned with the axial direction of the pressure roller 82. The skeleton frame of the image forming apparatus 1 includes: a front right column 121 and a rear right column 122 arranged adjacent to the fixing unit receiving portion 2e and spaced apart in the insertion / removal direction of the fixing unit 8; and a lower connecting beam 125 and a lower connecting beam 127 that are perpendicularly connected to the front right column 121 and the rear right column 122 respectively when viewed from the insertion / removal direction, and support the lower surface of the fixing unit 8. The image forming apparatus 1 includes: a pressure roller gear 84 that is rotatably integrated with the inner end of the pressure roller 82 of the fixing unit 8 in the insertion / removal direction; a drive gear 14 disposed at the inner end of the fixing unit receiving portion 2e in the insertion / removal direction and meshing with the pressure roller gear 84 when the fixing unit 8 is housed in the fixing unit receiving portion 2e; and a drive source (not shown) that drives the drive gear 14 to rotate. When the drive gear 14 and the pressure roller gear 84 transmit power, the transmission force F transmitted from the tooth surface 14a of the drive gear 14 to the tooth surface 84a of the pressure roller gear 84 at their meshing position M has a horizontal component Fh that presses the fixing unit 8 toward the front right post 121 and the rear right post 122 in the horizontal direction. Moreover, when the fixing unit 8 is housed in the fixing unit housing 2e, it is pressed by the front right post 121 and the rear right post 122 by the horizontal component Fh of the transmission force F and is positioned in the direction perpendicular to the insertion and removal direction (left and right direction).

[0079] With the above configuration, by inserting the fixing unit 8 into the fixing unit receiving part 2e from the front and performing printing processing on the image forming apparatus 1, the fixing unit 8 can be positioned by using the power F transmitted from the drive gear 14 to the pressure roller gear 84, pressing it against the front right column 121 and the rear right column 122. Therefore, compared with the positioning structure of conventional image forming apparatuses that uses a locking groove and a locking pin, the structure can be simplified. Furthermore, since it is not necessary to separately provide a force-applying mechanism for fixing the fixing unit 8 and a release mechanism for releasing the fixing, the number of parts can be reduced, and cost reduction can be achieved.

[0080] Furthermore, in this embodiment, when the drive gear 14 and the pressure roller gear 84 transmit power, when viewed from the insertion and removal direction of the fixing unit 8, the extension line of the transmission power F passes above the intersection point C of the vertical plane A of the surface of the fixing unit receiving part 2e (including the front and rear right columns 121, 122) and the horizontal plane B of the upper surface of the lower connecting beams 125, 127 (including the front and rear). Figure 9 ).

[0081] According to the above configuration, the power transmission F generates a fixing unit 8 that, with the intersection position C as the fulcrum, faces... Figure 9The torque that rotates counterclockwise. This ensures that the right side of the fixing unit 8 ( Figure 9 Press the front right column 121 and the rear right column 122 on the left side to maximize the positioning accuracy of the fixing unit 8 in the left and right directions.

[0082] Furthermore, in this embodiment, when the drive gear 14 and the pressure roller gear 84 transmit power, the horizontal component Fh and the vertical component Fv of the transmitted power F are equal.

[0083] With the above configuration, the fixing unit 8 can be pressed evenly on the right side in the horizontal direction and the lower side in the vertical direction. Therefore, it can prevent the fixing unit 8 from excessively pressing the front right column 121 and the rear right column 122, thereby causing the fixing unit 8 to float from the lower connecting beams 125 and 127. Furthermore, the positioning accuracy of the fixing unit 8 in both the left-right and up-down directions can be improved.

[0084] Furthermore, in this embodiment, the surfaces of the fixing unit receiving portion 2e of the front right column 121 and the rear right column 122 have two ridges R that extend in the vertical direction and are spaced apart in the insertion / removal direction. When the front right column 121 and the rear right column 122 are pushed by the horizontal component Fh of the transmission force F, the fixing unit 8 abuts against the two ridges R formed on the front right column 121 and the rear right column 122, respectively.

[0085] According to the above configuration, since the fixing unit 8 abuts against the front right column 121 and the rear right column 122 by using line contact, it can perform left and right positioning with high precision compared with the case of abutting by surface contact.

[0086] Furthermore, on the surface of the fixing unit 8 in this embodiment that is pressed by the front right column 121 and the rear right column 122 (the right side surface of this embodiment), a pair of abutment portions 83e are provided to abut against the front right column 121 and the rear right column 122 respectively. When the fixing unit 8 is pressed by the front right column 121 and the rear right column 122, each abutment portion 83e can abut against the two edges R of the front right column 121 and the rear right column 122. Specifically, the width of the abutment portion 83e is set to be greater than the interval between the two edges R.

[0087] According to the above configuration, by making the surface accuracy of the protruding side of the abutment seat 83e higher than that of other parts, and by making the protruding side of the abutment seat 83e with high surface accuracy abut against the ridge line R of the front right column 121 and the rear right column 122, the positioning accuracy of the fixing cover 83 in the left and right directions can be improved as much as possible.

[0088] (Variation Example 1)

[0089] Figure 13This represents a variation 1 of the above-described embodiment. Furthermore, in the following variations, for and Figure 9 The same structural elements are labeled with the same reference numerals and specific descriptions are omitted.

[0090] In the modified example, when the drive gear 14 and the pressure roller gear 84 transmit power, when viewed from the insertion and removal direction of the fixing unit 8, the extension line of the transmission power F passes through the intersection point C of the vertical plane A of the surface of the fixing unit receiving part 2e including the front right column 121 and the rear right column 122 and the horizontal plane B of the upper surface of the lower connecting beams 125 and 127 including the front and rear.

[0091] According to the above configuration, since the extension line of the transmission force F passes through the intersection C when viewed from the insertion / removal direction of the fixing unit 8, no torque is generated around the intersection C on the fixing unit 8. Therefore, the posture of the fixing unit 8 is prevented from dynamically changing due to the torque load caused by the transmission force F, thereby improving the positioning accuracy of the fixing unit 8 in the left-right and up-down directions.

[0092] (Variation Example 2)

[0093] Figure 14 This represents a variation 2 of the above-described embodiment. In this variation, when the drive gear 14 and the pressure roller gear 84 transmit power, the horizontal component Fh of the transmitted power F is greater than the vertical component Fv.

[0094] According to the above configuration, compared with the case where the horizontal component Fh and the vertical component Fv are equal, the fixing unit 8 can press the front right column 121 and the rear right column 122 more forcefully, thereby improving the positioning accuracy of the fixing unit 8 in the left and right directions. In addition, in this case, although the vertical component Fv pressed down by the fixing unit 8 is reduced, even if the vertical component Fv is small, the gravity acting on the fixing unit 8 can still press the lower connecting beams 125 and 127 at the front and rear, so the positioning accuracy of the fixing unit 8 in the up and down directions will not be compromised.

[0095] (Other implementation methods)

[0096] In the above embodiments and variations, the pressure roller 82 is used as the driving roller and the fixing roller 81 is used as the driven roller. However, it is not limited to this. The fixing roller 81 can also be used as the driving roller and the pressure roller 82 as the driven roller. In this case, it is sufficient to connect the driven gear to the drive shaft of the fixing roller 81 in a rotating integral manner and make the driving gear 14 mesh with the driven gear.

[0097] In the above embodiments and variations, a fixing roller 81 is illustrated as an example of a rotating fixing member, but it is not limited thereto; the rotating fixing member may also be an annular fixing belt. Furthermore, in the above embodiments, a pressure roller 82 is illustrated as an example of a rotating pressure member, but it is not limited thereto; the rotating pressure member may also be an annular pressure belt.

[0098] Furthermore, while a photocopier has been described as an example of image forming apparatus 1 in the above embodiment, it is not limited thereto. Image forming apparatus 1 may also be a printer, fax machine, photocopier, or digital multifunction printer (MFP), etc.

[0099] Industrial applicability

[0100] As described above, the present invention is applicable to image forming apparatuses, and in particular to printers, fax machines, copiers or digital multifunction printers (MFPs).

[0101] Explanation of reference numerals in the attached figures

[0102] 1: Image forming apparatus

[0103] 2: Main body of the image forming apparatus

[0104] 2e: Fixing Unit Containment Department

[0105] 8: Fixing unit

[0106] 14: Drive gear

[0107] 14a: Tooth surface

[0108] 81: Fusing roller (rotating fusing component)

[0109] 82: Pressure roller (rotating pressure component)

[0110] 83e: Abutting seat

[0111] 84: Pressure roller gear (driven gear)

[0112] 84a: Tooth surface

[0113] 121: Front right pillar (support column)

[0114] 122: Rear right pillar (support column)

[0115] 125: Lower connecting beam (crossbeam)

[0116] 127: Lower connecting beam (crossbeam)

[0117] C: Intersection position

[0118] F: Power transmission

[0119] Fh: Horizontal components

[0120] Fv: Vertical component

[0121] M: Engagement position

[0122] N: Gap

[0123] P: Paper (thin sheet)

[0124] R: Edge

Claims

1. An image forming apparatus comprising an image forming apparatus main body, the image forming apparatus main body including: The image forming apparatus is characterized by a fixing unit that fixes the toner image onto a thin sheet body by passing the sheet body through a slit formed by the pressure contact between a rotating fixing member and a rotating pressure member; and a fixing unit receiving portion that can be inserted and removed to receive the fixing unit. The insertion and extraction direction of the fixing unit relative to the fixing unit receiving portion is consistent with the axial direction of the rotating pressure member. The skeletal frame of the image forming apparatus includes: a pair of pillars disposed adjacent to the fixing unit receiving portion and spaced apart in the insertion / removal direction of the fixing unit, which position the fixing cover by abutting against the side of the fixing cover of the fixing unit; and a pair of crossbeams connected at right angles to the pair of pillars when viewed from the insertion / removal direction, supporting the lower surface of the fixing unit. The image forming apparatus further comprises: The driven gear is rotatably and integrally connected to the inner end of one of the rotating fixing member or the rotating pressurizing member of the fixing unit in the insertion and extraction direction. A drive gear is disposed at the inner end of the fixing unit receiving portion in the insertion / removal direction, and meshes with the driven gear when the fixing unit is received in the fixing unit receiving portion; as well as The drive source that drives the drive gear to rotate. When the driving gear and the driven gear transmit power, the power transmitted from the tooth surface of the driving gear to the tooth surface of the driven gear in their meshing position has a component that presses the fixing unit toward the pair of pillars in the horizontal direction. The fixing unit, in the state of being housed in the fixing unit housing, is positioned in a direction perpendicular to the insertion / removal direction by being pushed by the pair of pillars using the transmission force.

2. The image forming apparatus according to claim 1, characterized in that, When the driving gear and the driven gear transmit power, when viewed from the insertion and extraction direction of the fixing unit, the extension line of the transmission force passes above the intersection of the vertical plane of the surface of the fixing unit receiving part containing the pair of pillars and the horizontal plane of the upper surface containing the pair of crossbeams.

3. The image forming apparatus according to claim 1, characterized in that, When the driving gear and the driven gear transmit power, when viewed from the insertion and extraction direction of the fixing unit, the extension line of the transmission force passes through the intersection of the vertical plane of the surface of the fixing unit receiving part containing the pair of pillars and the horizontal plane of the upper surface containing the pair of crossbeams.

4. The image forming apparatus according to claim 1, characterized in that, When the driving gear and the driven gear transmit power, the horizontal component of the transmitted force is equal to the vertical component.

5. The image forming apparatus according to claim 1, characterized in that, When the driving gear and the driven gear transmit power, the power is transmitted in such a way that the horizontal component of the transmitted power is greater than the vertical component.

6. The image forming apparatus according to any one of claims 1 to 5, characterized in that, The surface of each pair of pillars on the side of the fixing unit receiving portion has two ridges that extend in the vertical direction and are spaced apart in the insertion and removal direction of the fixing unit. When the fixing unit is pushed against the pair of pillars by the transmission force, it abuts against the two ridges provided on each of the pillars.

7. The image forming apparatus according to claim 6, characterized in that, On the surface of the fixing unit that is pressed against the pair of pillars, there are protruding abutment portions that abut against the pair of pillars respectively. When the fixing unit is pressed against a pair of pillars, each of the abutting seats can abut against the two ridges formed on the pillars respectively.

Images