Image forming apparatus

Abstract

The present invention provides an image forming apparatus that can suppress positional displacement of the image formed on a sheet as it passes through a photosensitive drum, with respect to the sheet being fed by the feeding unit. [Solution] In the image forming apparatus 1, the apparatus body 9 has a first side frame 9L located on one side in the width direction relative to the drawer 2D, and a second side frame 9R located on the other side in the width direction relative to the drawer 2D. The first and second side frames 9L and 9R have guides 9L2 and 9R2 that guide the drawer 2D as it moves between a mounting position and an exposure position. The feeding unit 100 has a unit frame 100F that supports the feeding roller 21, the unit frame 100F having a first end 80L located on one side in the width direction fastened to the first side frame 9L, and a second end 90R located on the other side in the width direction fastened to the second side frame 9R.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses an example of a conventional image forming apparatus. In this image forming apparatus, a drawer is in a mounted position attached to the apparatus main body and is movable to an exposed position where at least a part thereof is located outside the apparatus main body. A photosensitive drum is rotatably supported by the drawer. A first roller is rotatably supported by the drawer and conveys a sheet in the conveyance direction toward the photosensitive drum. A second roller is rotatably supported by the apparatus main body and faces the first roller.

[0003] A positioning mechanism is provided between the apparatus main body and the drawer. The positioning mechanism positions the second roller with respect to the first roller in a state where the drawer is in the mounted position.

[0004] Although not disclosed in Patent Document 1, this image forming apparatus may include a feeding unit that is positioned upstream in the conveyance direction from the first roller and the second roller and is assembled to the apparatus main body, separately from a feeding roller that feeds a sheet from a sheet tray located at the bottom of the apparatus main body. The feeding roller included in this feeding unit feeds a sheet from the outside of the apparatus main body toward the first roller and the second roller.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the conventional image forming apparatus described above, since the second roller is positioned relative to the first roller supported by the drawer by a positioning mechanism, if the feed roller cannot be accurately positioned relative to the first roller, there is a problem in that it becomes difficult to suppress the positional displacement of the image formed on the sheet as it passes through the photosensitive drum when it is fed by the feed unit.

[0007] The present invention has been made in view of the above-mentioned conventional circumstances, and aims to provide an image forming apparatus that can suppress positional displacement of the image formed on a sheet when it passes through a photosensitive drum, with respect to the sheet being fed by a feeding unit. [Means for solving the problem]

[0008] The image forming apparatus of the present invention comprises the apparatus body and, A drawer that is mounted on the main body of the device and is movable to an exposed position where at least a portion of it is located outside the main body of the device, A photosensitive drum supported in the drawer so as to be rotatable about a rotation axis extending in the width direction, A first roller is rotatably supported in the drawer and conveys the sheet toward the photosensitive drum in the conveying direction, A second roller is rotatably supported on the main body of the device and faces the first roller, A feeding unit mounted on the main body of the apparatus, located upstream of the first and second rollers in the conveying direction, the feeding unit having a feeding roller that feeds a sheet from outside the main body of the apparatus toward the first and second rollers, A positioning mechanism for positioning the second roller relative to the first roller while the drawer is in the mounting position, An image forming apparatus comprising, The device body has a first side frame located on one side in the width direction relative to the drawer, and a second side frame located on the other side in the width direction relative to the drawer. The first side frame and the second side frame have guides for guiding the drawer as it moves between the mounting position and the exposed position. The feeding unit is characterized by having a unit frame that supports the feeding roller, wherein a first end located on one side in the width direction is fastened to the first side frame, and a second end located on the other side in the width direction is fastened to the second side frame.

[0009] In the image forming apparatus of the present invention, the first and second ends of the unit frame supporting the feed roller are fastened to a first side frame and a second side frame having guides for guiding a drawer. This allows the image forming apparatus to accurately position the feed roller relative to the first roller. Furthermore, the image forming apparatus can accurately position the feed roller relative to the second roller, which is positioned relative to the first roller by a positioning mechanism.

[0010] Therefore, the image forming apparatus of the present invention can suppress positional displacement of the image formed on a sheet as it passes through the photosensitive drum, with respect to the sheet being fed by the feeding unit. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a partial cross-sectional view of an image forming apparatus in an embodiment, showing the state in which the support plate of the unfolded feed tray is separated downward from the feed roller. [Figure 2] Figure 2 is a partial cross-sectional view similar to Figure 1, showing the drawer in a state where the cover has been opened and the drawer has been moved from the mounting position to the exposed position. [Figure 3] Figure 3 is a partial front view showing the first side frame, second side frame, drawer, feeding unit, etc. [Figure 4] Figure 4 is a partial perspective view showing the first side frame and feeding unit. [Figure 5] Figure 5 is a partial perspective view showing the second side frame and feeding unit. [Figure 6] Figure 6 is a perspective view showing a feeding unit, a conveyance frame, etc. [Figure 7] Figure 7 is a perspective view showing a conveyance frame, a second roller, etc. [Figure 8] Figure 8 is a partial perspective view showing a first roller, a conveyance frame, a second roller, a positioning mechanism, etc. [Figure 9] Figure 9 is a perspective view showing a feeding tray. [Figure 10] Figure 10 is a partial cross-sectional view similar to FIG. 1, showing a state where the support plate of the unfolded feeding tray rises and contacts the feeding roller. [Figure 11] Figure 11 is a perspective view showing a first feeding frame, a drive frame, a lifting mechanism, a sheet guide, a separation pad, etc. [Figure 12] Figure 12 is a perspective view showing a first feeding frame, a drive frame, a lifting mechanism, a sheet guide, a wire harness, etc. [Figure 13] Figure 13 is a perspective view showing a first feeding frame, a drive frame, a lifting mechanism, a photo interrupter, a sensor board, a wire harness, etc. [Figure 14] Figure 14 is a front view showing a first feeding frame, a lifting mechanism, a photo interrupter, a sensor board, etc. [Figure 15] Figure 15 is a cross-sectional view showing the A-A cross section of FIG. 14. [Figure 16] Figure 16 is a schematic partial cross-sectional view showing a first side frame, a motor, a first transmission gear, a drive frame, a second transmission gear, etc.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

[0013] (Example) As shown in Figure 1, the image forming apparatus 1 of the embodiment is an example of a specific embodiment of the image forming apparatus of the present invention. In Figure 1, the front 9S side of the apparatus body 9 is defined as the front of the apparatus, and the top side of the apparatus body 9 is defined as the top of the apparatus. The width direction of the image forming apparatus 1 is perpendicular to the front-to-back direction and the up-to-down direction. The side that is to the left when facing the front 9S of the apparatus body 9, that is, the front side of the page in Figure 1, is defined as one of the width directions. The side that is to the right when facing the front 9S of the apparatus body 9, that is, the back side of the page in Figure 1, is defined as the other width direction. The front-to-back direction, up-to-down direction and width direction shown in each of the figures from Figure 2 onward all correspond to Figure 1.

[0014] As shown in Figure 1, the image forming apparatus 1 comprises a main body 9, a paper feed cassette 2C, an image forming unit 2, and a transport unit 4.

[0015] The main body of the device 9 is roughly box-shaped and has a discharge tray 9T on its upper surface. The main body of the device 9 has a cover 9F that forms the upper part of the front surface 9S. When the cover 9F is upright, it closes the drawer opening 9H formed in the upper part of the front surface 9S.

[0016] The paper feed cassette 2C is located in the lower part of the main unit 9 and holds multiple sheets stacked together. The front of the paper feed cassette 2C forms the lower part of the front panel 9S. As shown in Figure 2, the user can replenish the paper feed cassette 2C by pulling it forward from the main unit 9.

[0017] As shown in Figure 1, the image forming unit 2 is located in the upper part of the main body 9 of the apparatus. While a detailed explanation is omitted, the image forming unit 2 comprises a plurality of process units 2P that form images on a sheet using an electrophotographic method, a drawer 2D that supports each process unit 2P, and a transfer belt, a scanner unit, and a fuser (not shown).

[0018] Each process unit 2P includes a photosensitive drum 2G, a toner storage unit (not shown), a developing roller, and a charger. The photosensitive drum 2G is supported in a drawer 2D so as to be rotatable around a rotation axis X1 that extends in the width direction.

[0019] To put it simply, the transport unit 4 includes a feed roller, a separation roller, a separation pad, and a pair of transport rollers (not shown), a first roller 41 and a second roller 42 as a resist roller pair, and a pair of discharge rollers (not shown). The second roller 42 faces the first roller 41 from below.

[0020] The transport unit 4 feeds sheets one by one from the paper cassette 2C using feed rollers, separation rollers and separation pads (not shown), and transports the sheets toward the first roller 41 and the second roller 42 using a pair of transport rollers (not shown).

[0021] The first roller 41 and the second roller 42 transport the sheet toward the photosensitive drum 2G of the image forming unit 2. The image forming unit 2 forms an image on the sheet. After that, the transport unit 4 uses a pair of discharge rollers (not shown) to transport the sheet with the image formed on it and discharge it into the discharge tray 9T.

[0022] <Mounting position and exposure position of the drawer> The image forming apparatus 1 is equipped with a feed tray 3. The feed tray 3 is a multi-purpose tray for feeding multiple types of sheets SH with different sizes and thicknesses to the image forming unit 2.

[0023] The cover 9F supports the feed tray 3. In Figure 1, the feed tray 3 is deployed so as to extend forward from the middle of the front surface 9S of the device body 9 in the vertical direction, but by raising the feed tray 3, it can be housed in the cover 9F.

[0024] The drawer 2D is in a mounting position attached to the main body 9 of the device. As shown in Figure 2, the cover 9F, with the supply tray 3 housed inside, swings its upper end forward and downward to open the drawer opening 9H.

[0025] In this state, the user can move the drawer 2D between the mounting position shown in Figure 1 and the exposed position, where at least a portion of it is located outside the main body 9 of the device, as shown in Figure 2, by grasping a handle (not shown) provided at the front end of the drawer 2D and pulling or pushing the drawer 2D. In other words, the drawer opening 9H can move from the mounting position to the exposed position and allow the drawer 2D to pass through when it moves from the exposed position to the mounting position. When the drawer 2D is in the exposed position, it is possible to detach or attach cartridges, etc., that function as process units 2P mounted on the drawer 2D. Also, when the drawer 2D is in the mounting position, the cover 9F can be opened and closed, and sheets SH can be fed from the feed tray 3, and images can be formed on the fed sheets SH.

[0026] The first roller 41 is rotatably supported on the drawer 2D and moves with the drawer 2D as the drawer 2D moves between the mounting position and the exposed position.

[0027] <First side frame and second side frame> As shown in Figure 3, the main body of the apparatus 9 has a first side frame 9L and a second side frame 9R. The first side frame 9L and the second side frame 9R are resin molded products manufactured by injection molding of thermoplastic resin or the like. The drawer 2D shown in Figure 3 is in the mounting position.

[0028] As shown in Figures 3 and 4, the first side frame 9L extends in the front-to-back and up-to-down directions along one side of the device body 9 in the width direction. The first side frame 9L is located on one side in the width direction relative to the drawer 2D.

[0029] As shown in Figures 3 and 5, the second side frame 9R extends in the front-to-back and up-to-down directions along the other side of the device body 9 in the width direction. The second side frame 9R is located on the other side in the width direction relative to the drawer 2D.

[0030] As shown in Figure 4, the first side frame 9L has a guide 9L2. The guide 9L2 is formed on the upper portion of the surface of the first side frame 9L that faces the other side in the width direction. The guide 9L2 has an upward-facing flat surface that extends substantially horizontally from the front end to the rear end of the first side frame 9L, and a recess that is recessed downward and connected to the rear end of the flat surface.

[0031] As shown in Figure 5, the second side frame 9R has a guide 9R2. The guide 9R2 is formed on the upper portion of the surface of the first side frame 9R that faces one direction in the width direction. The guide 9R2 has an upward-facing flat surface that extends substantially horizontally from the front end to the rear end of the first side frame 9R, and a recess that is recessed downward and connected to the rear end of the flat surface.

[0032] As simplified in Figure 2, the drawer 2D has two cam followers 2F. One cam follower 2F is rotatably supported at a rearward and upward corner of one side wall in the width direction of the drawer 2D. The other cam follower 2F is rotatably supported at a rearward and upward corner of the other side wall in the width direction of the drawer 2D.

[0033] Guides 9L2 and 9R2 guide the drawer 2D as it moves between the mounting position and the exposure position, with two cam followers 2F rolling along the guides 9L2 and 9R2. When the drawer 2D moves to the mounting position, the two cam followers 2F fall into recesses on the rear ends of the guides 9L2 and 9R2, holding the drawer 2D in the mounting position.

[0034] Although not shown in the diagram, the first side frame 9L and the second side frame 9R have multiple positioning surfaces that contact the drawer 2D held in the mounting position. The drawer 2D in the mounting position is precisely positioned in the vertical, horizontal, and width directions relative to the guides 9L2 and 9R2 by each positioning surface.

[0035] As shown in Figure 4, the first side frame 9L has a positioning boss 9L1. As shown in Figure 3, the positioning boss 9L1 is a cylindrical projection that protrudes forward from the lower front portion of the first side frame 9L. The positioning boss 9L1 is located below the drawer 2D in the mounting position.

[0036] As shown in Figure 5, the second side frame 9R has a positioning projection 9R1. As shown in Figure 3, the positioning projection 9R1 is a roughly "+" shaped projection that protrudes forward from the lower part of the front surface of the second side frame 9R. The positioning projection 9R1 is located below the drawer 2D in the mounting position.

[0037] <Conveyor frame and sheet metal guide> As shown in Figures 1 and 6 to 8, the main body of the device 9 has a transport frame 70 and a sheet metal guide 78. In Figure 6, the feeding unit 100, which will be described later, is located in front of the transport frame 70 and the sheet metal guide 78.

[0038] As shown in Figure 7, the conveying frame 70 extends in the width direction and rotatably supports the second roller 42 at its upper end. The conveying frame 70 is a resin molded product manufactured by injection molding of thermoplastic resin or the like.

[0039] One end 70L of the conveying frame 70, located on one side in the width direction, is located on one side in the width direction and below the end of the second roller 42, also located on one side in the width direction. The one end 70L extends in a substantially flat shape in the vertical and width directions.

[0040] A screw insertion hole 70L1 is formed in the lower part of one end 70L, penetrating in the front-to-back direction. A positioning hole 70L3 is formed in the upper part of one end 70L, penetrating in the front-to-back direction. The positioning hole 70L3 is a round hole.

[0041] The other end 70R of the conveying frame 70, located on the other side in the width direction, is located on the other side in the width direction and below the other end of the second roller 42. The other end 70R extends in a substantially flat shape in the vertical and width directions.

[0042] At the upper end of the other end 70R, a screw insertion hole 70R1 is formed so as to penetrate in the front-to-back direction. At the lower end of the other end 70R, a screw insertion hole 70R2 is formed so as to penetrate in the front-to-back direction. The screw insertion holes 70R1 and 70R2 are elongated holes that are longer in the width direction.

[0043] Below the screw insertion hole 70R1 at the other end 70R, a positioning hole 70R3 is formed so as to penetrate in the front-to-back direction. The positioning hole 70R3 is an elongated hole that is long in the width direction.

[0044] The sheet metal guide 78 is made of steel sheet metal that has been pressed and bent. The sheet metal guide 78 has a lower portion that extends flat in the vertical and width directions, and an upper portion that extends upward and backward from the upper end of the lower portion in a curved direction. Small pieces formed on both ends of the sheet metal guide 78 in the width direction are fastened to the conveying frame 70, thereby assembling the sheet metal guide 78 to the conveying frame 70.

[0045] As shown in Figure 1, the transport frame 70 and the sheet metal guide 78 constitute part of the feeding path that guides the sheet from the paper feed cassette 2C to the first roller 41 and the second roller 42 in the transport section 4.

[0046] Although not shown in the diagram, the transport frame 70 with the sheet metal guide 78 assembled is assembled to the first side frame 9L and the second side frame 9R by the positioning hole 70L3 fitting with the positioning boss 9L1 of the first side frame 9L and the positioning hole 70R3 fitting with the positioning projection 9R1 of the second side frame 9R. Then, the screw 70F1 shown in Figure 7 passes through the screw insertion hole 70L1 of the transport frame 70 and is screwed into a screw hole (not shown) formed on the front surface of the first side frame 9L. The screw 70F2 shown in Figures 6 and 7 passes through the screw insertion hole 70R2 of the transport frame 70 and is screwed into a screw hole (not shown) formed on the front surface of the second side frame 9R. As a result, the transport frame 70 is fastened to the first side frame 9L and the second side frame 9R.

[0047] The screw insertion holes 70R1 of the transport frame 70 are used when fastening the feeding unit 100, which will be described later, to the first side frame 9L and the second side frame 9R.

[0048] <Positioning mechanism> As shown in Figures 6 and 8, the image forming apparatus 1 is equipped with a positioning mechanism 8. The positioning mechanism 8 includes a positioning groove 2D1G, rails 71L and 71R, bearings 72L and 72R, and compression coil springs 73L and 73R, which will be described below.

[0049] Although Figure 8 omits the illustration of the drawer 2D in the mounting position, the drawer 2D has first roller bearings 2D1L and 2D1R. The first roller bearing 2D1L rotatably supports one end of the first roller 41 in the width direction on the axis of rotation. The first roller bearing 2D1R rotatably supports the other end of the first roller 41 in the width direction on the axis of rotation.

[0050] The first roller bearings 2D1L and 2D1R have a positioning groove 2D1G. The positioning groove 2D1G is formed in the portion of the first roller bearings 2D1L and 2D1R that is located below and behind the rotation axis of the first roller 41, and is recessed upward and forward so as to approach the rotation axis of the first roller 41.

[0051] As shown in Figures 6 and 7, the transport frame 70 supports the bearings 72L and 72R so that they can move in a straight line by rails 71L and 71R.

[0052] Bearing 72L rotatably supports one end of the second roller 42 in the width direction on the axis of rotation. Bearing 72R rotatably supports the other end of the second roller 42 in the width direction on the axis of rotation.

[0053] The bearings 72L and 72R have a positioning projection 72G. The positioning projection 72G has a cylindrical outer surface that can be fitted into the positioning groove 2D1G.

[0054] As shown in Figure 8, a compression coil spring 73L is located between the transport frame 70 and the bearing 72L. A compression coil spring 73R is located between the transport frame 70 and the bearing 72R.

[0055] With the drawer 80 in the mounting position, the bearings 72L and 72R move linearly along the rails 71L and 71R, allowing the second roller 42 to move closer to and further away from the first roller 41. The compression coil springs 73L and 73R press against the bearings 72L and 72R, biasing the second roller 42 toward the first roller 41. As a result, the positioning protrusions 72G of the bearings 72L and 72R fit into the positioning grooves 2D1G of the first roller bearings 2D1L and 2D1R.

[0056] In this way, the positioning mechanism 8 positions the second roller 42 relative to the first roller 41 while the drawer 2D is in the mounting position.

[0057] <Feeding tray> As shown in Figures 1, 9, and 10, the upward-facing surface of the unfolded feeding tray 3 is a support surface 3A capable of supporting the sheet SH. The feeding tray 3 comprises a feeding tray body 30, a support plate 31, and a sub-tray 30E.

[0058] The feed tray body 30 is rotatably supported by the cover 9F. When the feed tray 3 is deployed, the feed tray body 30 extends forward and inclined upward from the front 9S.

[0059] The support plate 31 is located on the side of the feed tray body 30 that faces upward. The support plate 31 is supported by the feed tray body 30 so as to be rotatable around the axis X31. The axis X31 extends in the width direction at the front end of the support plate 31. The support plate 31 moves up and down as shown in Figures 1 and 10 when the lifting mechanism 6, which will be described later, is activated.

[0060] The sub-tray 30E is pulled out from the main feed tray 30 and extends in an upward sloping direction towards the front.

[0061] The support surface 3A is composed of an upward-facing surface of the support plate 31, an upward-facing surface of the sub-tray 30E, and an upward-facing surface between the support plate 31 and the sub-tray 30E in the feeding tray body 30. The support surface 3A supports the sheet SH, which is the object to be fed by the feeding roller 21 (described later), on the outside of the device body 9.

[0062] <Feeding Unit> As shown in Figure 1, the image forming apparatus 1 includes a feeding unit 100 for feeding the sheet SH, which is supported on the support surface 3A, to the first roller 41 and the second roller 42.

[0063] As shown in Figure 6, the feeding unit 100 is positioned in front of the transport frame 70 and the sheet metal guide 78, and is assembled to the first side frame 9L and the second side frame 9R as shown in Figures 3 to 5. The transport frame 70 is not shown in Figures 3 to 5.

[0064] As shown in Figure 1, the first roller 41 and the second roller 42 transport the sheet SH, which is fed by the feeding unit 100, toward the photosensitive drum 2G in the transport direction DT1. The transport direction DT1 is a direction that moves substantially horizontally backward and is perpendicular to the width direction. The feeding unit 100 is mounted on the main body of the device 9 and is located upstream of the first roller 41 and the second roller 42 in the transport direction DT1.

[0065] As shown in Figures 3, 4, and 6, the feeding unit 100 has a unit frame 100F and a sheet guide 89.

[0066] The unit frame 100F includes a first feed frame 90, a second feed frame 29, and a drive frame 80. The first feed frame 90 and the second feed frame 29 are examples of the "feed frame" of the present invention.

[0067] The first feed frame 90, the second feed frame 29, and the drive frame 80 are each resin molded products manufactured by injection molding of thermoplastic resin or the like. The seat guide 89 is also a resin molded product manufactured by injection molding of thermoplastic resin or the like.

[0068] As shown in Figures 1 and 3, the first feed frame 90 and the sheet guide 89 are located below the second feed frame 29.

[0069] As shown in Figures 11 to 14, the first feed frame 90 extends in the width direction. As shown in Figures 11 and 12, the sheet guide 89 also extends in the width direction. The first feed frame 90 supports the sheet guide 89. The sheet guide 89 covers the upper part of the first feed frame 90 and also covers the upper front part of the first feed frame 90.

[0070] As shown in Figure 14, the first feed frame 90 has two sides 90S1 and 90S2. Side 90S1 is located on one side in the width direction of the first feed frame 90 and faces the other side in the width direction. Side 90S2 is located on the other side in the width direction of the first feed frame 90 and faces the one side in the width direction. The two sides 90S1 and 90S2 and the upper surface of the sheet guide 89 define the space through which the sheet SH passes.

[0071] As shown in Figure 11, the first feeding frame 90 has connecting portions 99L and 99R at the upper end of the portion located outside in the width direction of the two sides 90S1 and 90S2.

[0072] As shown in Figure 6, the second feeding frame 29 also extends in the width direction, with one end in the width direction fastened to the connecting portion 99L and the other end in the width direction fastened to the connecting portion 99R. The second feeding frame 29 is fastened to the first feeding frame 90 in a state where it is aligned with the first feeding frame 90 in the vertical direction.

[0073] As shown in Figure 1, the feeding unit 100 has a feeding roller 21, a separation roller 22, and a separation pad 22A. The second feeding frame 29 rotatably supports the feeding roller 21 and the separation roller 22. The first feeding frame 90 supports the separation pad 22A. The separation roller 22 and the separation pad 22A face each other in the vertical direction.

[0074] As shown in Figures 14 and 15, the first feed frame 90 has a connecting end 90J. The connecting end 90J is an end located on one side in the width direction of the first feed frame 90. The connecting end 90J is located on one side in the width direction relative to the separation pad 22A.

[0075] The connecting end 90J has a fastening boss 90J1 located at the upper and front corner, a fastening boss 90J2 located at the upper and rear corner, and a fastening boss 90J3 located at the lower and front corner. Each of the fastening bosses 90J1 to 90J3 protrudes cylindrically from the connecting end 90J in one direction in the width direction, and has a female thread recessed in its center.

[0076] Three screws are inserted into the drive frame 80, which is located on one side in the width direction of the connecting end 90J of the first feed frame 90, and then screwed into the fastening bosses 90J1 to 90J3, thereby fastening the drive frame 80 to the connecting end 90J of the first feed frame 90. As shown in Figure 6, the drive frame 80 is fastened to the first feed frame 90 in a state that is aligned in the width direction with the first feed frame 90 and the second feed frame 29.

[0077] As shown in Figure 12, the drive frame 80 has a first end 80L. The first end 80L is an end located on one side in the width direction of the drive frame 80, and is an end located on one side in the width direction of the unit frame 100F.

[0078] The first end portion 80L has an upper portion located on one side in the width direction relative to the connecting portion 99L, and a lower portion located separately below the upper portion.

[0079] A screw insertion hole 80L1 is formed at the upper end of the upper portion of the first end 80L, penetrating in the front-to-back direction. A screw insertion hole 80L2 is formed at the lower end of the lower portion of the first end 80L, penetrating in the front-to-back direction.

[0080] A positioning hole 80L3 is formed below the screw insertion hole 80L1 in the upper part of the first end portion 80L, extending through in the front-to-back direction. The positioning hole 80L3 is a round hole.

[0081] The first feeding frame 90 has a second end 90R. The second end 90R is the end located on the other side in the width direction of the first feeding frame 90, and is the end located on the other side in the width direction of the unit frame 100F.

[0082] The second end portion 90R has an upper portion located on the other side in the width direction from the connecting portion 99R, and a lower portion located separately below the upper portion.

[0083] The upper portion of the second end 90R extends in a substantially flat shape in the vertical and width directions. A screw insertion hole 90R1 is formed on the upper end side of the upper portion of the second end 90R so as to penetrate in the front-to-back direction.

[0084] The lower portion of the second end 90R also extends in a substantially flat shape in the vertical and width directions. A screw insertion hole 90R2 is formed at the lower end of the lower portion of the second end 90R so as to penetrate in the front-to-back direction.

[0085] Below the screw insertion hole 90R1 in the upper part of the second end portion 90R, a positioning hole 90R3 is formed so as to penetrate in the front-to-back direction. The positioning hole 90R3 is an elongated hole that is longer in the width direction.

[0086] The feeding unit 100 is positioned in front of the transport frame 70 and the sheet metal guide 78, and as shown in Figure 3, it is assembled to the first side frame 9L and the second side frame 9R by having the positioning hole 80L3 engage with the positioning boss 9L1 of the first side frame 9L and the positioning hole 90R3 engage with the positioning projection 9R1 of the second side frame 9R.

[0087] The positioning boss 9L1 positions the unit frame 100F relative to the first side frame 9L. The positioning projection 9R1 positions the unit frame 100F relative to the second side frame 9R.

[0088] Then, as shown in Figures 3, 4, and 11, screw 80F1 passes through screw insertion hole 80L1 of the drive frame 80 and is screwed into a screw hole (not shown) formed on the front surface of the first side frame 9L. Screw 80F2 passes through screw insertion hole 80L2 of the drive frame 80 and is screwed into a screw hole (not shown) formed on the front surface of the first side frame 9L.

[0089] As shown in Figures 3, 5, 7, and 11, screw 90F1 passes through screw insertion hole 90R1 of the first feed frame 90 and screw insertion hole 70R1 of the transport frame 70 and is screwed into a screw hole (not shown) formed on the front surface of the second side frame 9R. As shown in Figures 3, 5, and 11, screw 90F2 passes through screw insertion hole 90R2 of the feed frame 90 and is screwed into a screw hole (not shown) formed on the front surface of the second side frame 9R.

[0090] As a result, the unit frame 100F is fastened at its first end 80L to the first side frame 9L, and at its second end 90R to the second side frame 9R.

[0091] The insertion direction of the screws 80F1 and 80F2 for fastening the first end 80L to the first side frame 9L, and the insertion direction of the screws 90F1 and 90F2 for fastening the second end 90R to the second side frame 9R, are the same direction and proceed from front to back along the transport direction DT1.

[0092] The unit frame 100F, which has the first feeding frame 90, the second feeding frame 29, and the drive frame 80, is a reinforcing frame that extends in a beam-like manner in the width direction and is supported at both ends, and constitutes a part of the internal frame of the main body of the device 9.

[0093] As shown in Figure 2, the area where the upper screws 80F1 and 90F1 are located is defined as range AF1. The area where the lower screws 80F2 and 90F2 are located is defined as range AF2.

[0094] With the cover 9F open through the drawer opening 9H, the portion of the cover 9F closest to the front surface 9S of the device body 9 is located below the range AF1, thus opening up the range AF1. This allows the upper fastening of the first end 80L to the first side frame 9L and the upper fastening of the second end 90R to the second side frame 9R to be released.

[0095] With the paper feed cassette 2C pulled forward from the main body 9, range AF2 is opened. This allows the lower fastening of the first end 80L to the first side frame 9L and the lower fastening of the second end 90R to the second side frame 9R to be released.

[0096] As shown in Figures 13 and 14, the first feeding frame 90 has a rear wall 94, a base wall 95, and two support walls 96.

[0097] The rear wall 94 extends in the width direction from the second end 90R to the connecting end 90J of the first feeding frame 90, and also extends in the vertical direction.

[0098] The base wall 95 is located in front of the rear wall 94. The rear end edge of the base wall 95 is connected to the lower end edge of the rear wall 94. The base wall 95 extends in the width direction from the second end 90R to the connecting end 90J of the first feeding frame 90, and also extends in the front-rear direction.

[0099] Each support wall 96 is connected to the center of the rear wall 94 in the width direction and is spaced apart from each other in the width direction. Each support wall 96 protrudes forward from the rear wall 94 and extends in the vertical direction. As shown in Figure 13, the lower end of the front edge of each support wall 96 is connected to the front edge of the base wall 95.

[0100] <Motor, first transmission gear, first drive train and second drive train> As shown in Figure 16, the first side frame 9L supports the motor M1, the first transmission gear G1, and several gear groups (not shown).

[0101] Motor M1 generates driving force by operating under the control of a control unit (not shown). The driving force of motor M1 is appropriately transmitted to each operating element via multiple gear groups, clutches, etc.

[0102] The first transmission gear G1 rotates when the driving force of the motor M1 is transmitted to it via a group of gears. The driving force of the motor M1 is transmitted from the first transmission gear G1 via a group of gears along arrows Y1 in Figure 16 and arrows Y2 and Y3 in Figure 8, causing the first roller 41 and the second roller 42 to rotate.

[0103] As shown in Figure 16, the image forming apparatus 1 is equipped with a first drive train PS1. The first drive train PS1 is for transmitting the driving force of the motor M1 to the feed roller 21. The first drive train PS1 has a second transmission gear G2. The second transmission gear G2 meshes with the first transmission gear G1. The first transmission gear G1 transmits the driving force to the second transmission gear G2 of the first drive train PS1.

[0104] Furthermore, the first drive train PS1 includes the transmission gear G2A shown in Figures 12 and 15, the transmission gear G2B shown in Figures 12 and 15, the transmission gear G2C shown in Figure 16, the transmission gear G2D shown in Figures 13 and 16, and the transmission gear G2F shown in Figure 6. The transmission gear G2F rotates integrally with the rotation axis of the separation roller 22.

[0105] Although not shown in the diagram, the first drive train PS1 also has a number of transmission gears located between the rotation axis of the separation roller 22 and the rotation axis of the feed roller 21.

[0106] As shown in Figures 12 and 16, the drive frame 80 supports the transmission gears G2A, G2B, G2C, and G2D, which are part of the first drive train PS1. The second feed frame 29 supports the transmission gears G2F and other parts, which are other parts of the first drive train PS1.

[0107] As shown in Figures 14 and 15, the image forming apparatus 1 is equipped with a second drive column PS2. The second drive column PS2 is for transmitting driving force to the lifting mechanism 6, which will be described later. The second drive column PS2 has a drive cam C2, a metal shaft 61, and a driven cam 60.

[0108] As shown in Figure 14, the drive cam C2 is integrally formed with the transmission gear G2B of the first drive train PS1. The drive cam C2 protrudes toward the other side in the width direction so as to approach the connecting end 90J. As shown in Figure 15, the drive cam C2 is an eccentric cam. In other words, the second drive train PS2 branches off from the first drive train PS1.

[0109] As shown in Figure 13, the metal shaft 61 is a cylindrical steel column. The metal shaft 61 is located slightly above the base wall 95 and slightly behind the front edge of the base wall 95, and extends in the width direction.

[0110] One end of the metal shaft 61 in the width direction is rotatably supported by the first feed frame 90 on the side of the connecting portion 90J. The other end of the metal shaft 61 in the width direction is rotatably supported by the first feed frame 90 on the side of the second end 90R.

[0111] As shown in Figures 14 and 15, the driven cam 60 is fixed to one end of the metal shaft 61 in the width direction.

[0112] As shown in Figure 15, the metal shaft 61 is located in front of the axis of the drive cam C2. The driven cam 60 has a fixed portion 60A fixed to the metal shaft 61 and a contact portion 60B that protrudes from the fixed portion 60A in one direction in the width direction at a position eccentrically downward from the metal shaft 61. The contact portion 60B is slidable in contact with the outer circumferential surface of the drive cam C2.

[0113] The first feed frame 90 supports the metal shaft 61 and driven cam 60, which are part of the second drive train PS2, and the lifting mechanism 6, which will be described later. The drive frame 80 supports the drive cam C2, which is another part of the second drive train PS2.

[0114] As shown in Figure 16, the height of the gear teeth of the second transmission gear G2 is defined as height H1. The height of the gear teeth of the first transmission gear G1 is also height H1. The height of the gear teeth of the transmission gear G2D of the first drive train PS1 is defined as height H2. The height of the gear teeth of the transmission gears G2A to G2C, G2F, etc., other than the second transmission gear G2 in the first drive train PS1 is also height H2.

[0115] The gear tooth height H1 of the first transmission gear G1 and the second transmission gear G2 is greater than the gear tooth height H2 of the other transmission gears G2A to G2D, G2F, etc. in the first drive train PS1, excluding the second transmission gear G2. The first transmission gear G1 and the second transmission gear G2 are so-called high-tooth gears.

[0116] The range A1 in which the first transmission gear G1 and the second transmission gear G2 mesh in the vertical direction overlaps with at least a portion of the range A2 in which the positioning boss 9L1 exists in the vertical direction.

[0117] <Lifting mechanism> As shown in Figures 13 to 15, the image forming apparatus 1 is equipped with a lifting mechanism 6. The lifting mechanism 6 has two oscillating gears 63 and two arms 65.

[0118] As shown in Figure 14, the oscillating gear 63 located on one side in the width direction is fixed to the end of the metal shaft 61 located on one side in the width direction, adjacent to the fixed portion 60A of the driven cam 60 from the other side in the width direction. The oscillating gear 63 located on the other side in the width direction is fixed to the other end of the metal shaft 61 in the width direction. As shown in Figure 15, each oscillating gear 63 is a fan-shaped gear with gear teeth formed on its upper portion.

[0119] The feeding unit 100 includes a biasing spring 69L shown in Figure 15 and a biasing spring 69R shown in Figure 6. The second biasing springs 69L and 69R are tension coil springs.

[0120] As shown in Figure 14, a spring retaining portion 60S is formed on the fixed portion 60A of the driven cam 60. Although not shown in the figure, the lower end of the second biasing spring 69L is locked to the spring retaining portion 60S. As shown in Figure 15, the upper end of the biasing spring 69L is locked to a spring retaining portion located near the fastening boss 90J1 at the connecting end 90J.

[0121] As shown in Figure 6, the lower end of the biasing spring 69R is locked to the spring retaining portion 63S of the oscillating gear 63 located on the other side in the width direction. The upper end of the biasing spring 69R is locked to the spring retaining portion located near the positioning hole 90R3 at the second end portion 90R.

[0122] The oscillating gear 63 located on one side in the width direction and the oscillating gear 63 located on the other side in the width direction are biased by biasing springs 69L and 69R to rotate in a clockwise direction in the plane of Figure 15. Due to the biasing force of the biasing springs 69L and 69R, the contact portion 60B of the driven cam 60 is pressed against the outer circumferential surface of the drive cam C2.

[0123] As shown in Figure 14, the arm 65 located on one side in the width direction is pivotably supported on the connecting end 90J side of the first feed frame 90 at a position above the oscillating gear 63 located on the other side in the width direction. The arm 65 located on the other side in the width direction is pivotably supported on the second end 90R side of the first feed frame 90 at a position above the oscillating gear 63 located on the other side in the width direction. In other words, each arm 65 corresponds one-to-one with each oscillating gear 63.

[0124] As shown in Figure 15, each arm 65 has gear teeth that mesh with the gear teeth of each oscillating gear 63, and extends forward of those gear teeth. The front end of each arm 65 is located in front of the first feed frame 90.

[0125] As shown in Figure 9, the support plate 31 has two passive protrusions 31A. Each passive protrusion 31A protrudes outward in the width direction from one corner located on the rear end side of the support plate 31 and from the other corner located on the rear end side of the support plate 31 and from the width direction.

[0126] Although not shown in the diagram, each arm 65 has its front end in contact with each passive projection 31A of the support plate 31 from below. In this way, each arm 65 determines the vertical position of the support plate 31.

[0127] When the image forming apparatus 1 is in standby mode, the second drive train PS2 stops the drive cam C2 at the position shown in Figure 15. In this state, each arm 65 positions the support plate 31 at the position shown in Figure 1.

[0128] When feeding the sheet SH, supported on the support surface 3A of the feeding tray 3, toward the image forming unit 2, the driving force of the motor M1 is transmitted to the second drive column PS2 at a predetermined timing. Then, the drive cam C2 rotates approximately half a turn clockwise from the position shown in Figure 15 and stops at that position. At this time, the drive cam C2 transmits the driving force of the motor M1 to the driven cam 60.

[0129] Then, the driven cam 60, along with the metal shaft 61 and each oscillating gear 63, is biased by the biasing springs 69L and 69R and oscillates clockwise in the plane of the paper. Each arm 65 oscillates counterclockwise in the plane of the paper as driving force is transmitted from each oscillating gear 63, and the front end of each arm 65 lifts each passive protrusion 31A of the support plate 31. As a result, each arm 65 raises the support plate 31 to the position shown in Figure 10, bringing it closer to the feed roller 21.

[0130] In other words, the biasing springs 69L and 69R bias the lifting mechanism 6 so that the support plate 31 is brought closer to the feed roller 21.

[0131] Subsequently, when the image forming operation on the sheet SH supported on the support surface 3A is completed and the image forming apparatus 1 returns to the standby state, the driving force of the motor M1 is transmitted to the second drive column PS2 at a predetermined timing. Then, the drive cam C2 rotates further by about half a turn in the clockwise direction of the paper and stops at the position shown in Figure 15. At this time as well, the drive cam C2 transmits the driving force of the motor M1 to the driven cam 60.

[0132] As a result, the driven cam 60, together with the metal shaft 61 and each oscillating gear 63, oscillates counterclockwise in the plane of the paper against the biasing force of the biasing springs 69L and 69R. Each arm 65 oscillates clockwise in the plane of the paper as driving force is transmitted from each oscillating gear 63, and each arm 65 descends while its front end remains in contact with each passive projection 31A of the support plate 31 from below. As a result, each arm 65 lowers the support plate 31 to the position shown in Figure 1, separating it from the feed roller 21.

[0133] In other words, the lifting mechanism 6 receives the driving force of the motor M1 via the drive cam C2, driven cam 60, and metal shaft 61 of the second drive train PS2, which moves the support plate 31 up and down, causing the support plate 31 to move closer to and further away from the feed roller 21.

[0134] <Feeding roller, separation roller, separation pad, and biasing spring> As shown in Figure 1, the lower portions of the feed roller 21 and the separation roller 22, which are rotatably supported on the second feed frame 29, are exposed below the second feed frame 29.

[0135] The feeding roller 21 is located above the support surface 3A and in front of the rear end 3D of the support surface 3A. The separating roller 22 is located behind the rear end 3D of the support surface 3A.

[0136] As shown in Figure 11, the seat guide 89 has a restricting surface 89A and a guide surface 89B. The restricting surface 89A is a forward-facing surface formed by the front end surfaces of a plurality of ribs aligned in the width direction. The restricting surface 89A is inclined such that its upper end is located behind its lower end. The guide surface 89B is connected to the upper end of the restricting surface 89A. The guide surface 89B is an upward-facing surface formed by the upper end surfaces of a plurality of ribs aligned in the width direction. The guide surface 89B extends while inclining upward in a backward direction.

[0137] A pad opening 89H is formed in the center of the width direction of the guide surface 89B. The sheet guide 89 exposes the separation pad 22A from the guide surface 89B through the pad opening 89H.

[0138] As shown in Figure 1, the restricting surface 89A faces the rear end 3D of the support surface 3A from behind. With the support plate 31 in the lowered position, the restricting surface 89A restrains the front end of the sheet SH supported by the support surface 3A.

[0139] As shown in Figures 13 and 14, in the first feeding frame 90, the two support walls 96 are positioned to sandwich the separation pad 22A from the outside in the width direction, and support the separation pad 22A so that it can move toward and away from the separation roller 22. The separation pad 22A is pressed toward the separation roller 22 by a biasing spring.

[0140] As shown in Figure 10, when the lifting mechanism 6 is activated and the support plate 31 rises, the feed roller 21 comes into contact with the uppermost sheet SH supported on the support surface 3A on the outside of the main body of the device 9. In this state, the feed roller 21 rotates and feeds the uppermost sheet SH toward the separation roller 22. The guide surface 89B guides the sheet SH being fed by the feed roller 21.

[0141] As shown in Figure 1, the separation roller 22 takes over the sheets SH fed by the feeding roller 21 and transports them. At this time, if there are multiple sheets SH being fed, the separation roller 22 and the separation pad 22A separate them one by one.

[0142] The first roller 41 and the second roller 42 transport the sheet SH, which is fed by the feeding roller 21, the separating roller 22, and the separating pad 22A, toward the photosensitive drum 2G of the image forming unit 2.

[0143] The process unit 2P of the image forming unit 2 forms an image on the sheet SH, which is conveyed by the first roller 41 and the second roller 42. Then, the conveying unit 4 conveys the sheet SH with the image formed on it using a pair of discharge rollers (not shown) and discharges it into the discharge tray 9T. When the image forming operation is completed, the lifting mechanism 6 operates and the support plate 31 descends, as shown in Figure 1.

[0144] <Configuration for detecting the presence or absence of a sheet being fed by a feeding roller and the presence or absence of a sheet being supported by a support plate> As shown in Figures 13 and 14, the feeding unit 100 includes an actuator 39, an upper actuator 37, a lower actuator 38, a sensor board B1, and a wire harness W1.

[0145] The actuator 39 integrally includes a pivot shaft 39A, a contact portion 39B, and a shutter 39C.

[0146] The pivot shaft 39A is located forward of the upper end edge of the rear wall 94 of the first feed frame 90 and extends in the width direction, on the other side of the width direction from the separation pad 22A. The pivot shaft 39A is rotatably supported by the first feed frame 90.

[0147] The contact portion 39B protrudes upward from the pivot shaft 39A at a position close to the separation pad 22A. As shown in Figure 11, the upper part of the contact portion 39B is located above the guide surface 89B.

[0148] As shown in Figure 13, the shutter 39C is a plate-like piece that protrudes downward from the pivot shaft 39A at a position separated from the contact portion 39B in the other direction in the width direction, and extends in the circumferential direction of the pivot shaft 39A.

[0149] Although not shown in the diagram, the actuator 39 rotates its pivot shaft 39A when its contact portion 39B is pressed against the sheet SH being fed by the feed roller 21, causing the shutter 39C to move forward and upward.

[0150] As shown in Figures 3 and 6, the upper actuator 37 integrally includes a pivot shaft 37A, a contact portion 37B, and a transmission lever 37D.

[0151] The pivot shaft 37A is located inside the front end edge of the second feed frame 29 and extends in the width direction, on the other side of the width direction from the separation pad 22A. The pivot shaft 37A is rotatably supported by the second feed frame 29.

[0152] The contact portion 37B protrudes downward from the pivot shaft 37A at a position close to the separation pad 22A and at a position forward and separated from the contact portion 39B of the actuator 39. The lower part of the contact portion 37B is located forward of the regulating surface 89A.

[0153] The transmission lever 37D protrudes downward from the other end in the width direction of the pivot shaft 37A, bending as it goes.

[0154] As shown in Figures 13 and 14, the lower actuator 38 integrally includes a pivot shaft 38A, a transmission lever 38D, and a shutter 38C.

[0155] Although not shown in the diagram, the pivot shaft 38A is supported on the back side of the seat guide 89. The pivot shaft 38A is located in front of the pivot shaft 39A of the actuator 39 and extends in the width direction.

[0156] The transmission lever 38D protrudes forward from the other end in the width direction of the pivot shaft 38A and has an arc-shaped elongated hole. As shown in Figure 6, the transmission lever 38D is connected to the transmission lever 37D by a convex shaft formed at the lower end of the transmission lever 37D fitting into the elongated hole of the transmission lever 38D.

[0157] As shown in Figures 13 and 14, the shutter 38C is a plate-like piece that protrudes downward from the pivot shaft 38A at a position separated from the shutter 39C of the actuator 39 in the other direction in the width direction, and extends in the circumferential direction of the pivot shaft 38A.

[0158] Although not shown in the diagram, the upper actuator 37 rotates its pivot shaft 37A when its contact portion 37B is pressed against the seat SH supported by the support plate 31, causing the transmission lever 37D to move backward and upward.

[0159] Although not shown in the diagram, the lower actuator 38 rotates its pivot shaft 38A when the movement of the transmission lever 37D is transmitted to the transmission lever 38D, causing the shutter 38C to move forward and upward.

[0160] The first feeding frame 90 has a substrate support portion 90B. The substrate support portion 90B is formed on the upper surface of the base wall 95 at a position between the support wall 96 located on the other side in the width direction and the side surface 90S2.

[0161] The substrate support portion 90B supports the sensor substrate B1. As shown in Figure 14, the substrate support portion 90B supports the sensor substrate B1 at a position closer to the other side than the center CL1 in the width direction of the unit frame 100F. The substrate support portion 90B supports the sensor substrate B1 before the feeding unit 100 is assembled to the first side frame 9L and the second side frame 9R.

[0162] As shown in Figures 13 and 14, the sensor substrate B1 has photointerrupters S1 and S2. The photointerrupters S1 and S2 have a well-known configuration, so their explanation will be kept brief, but they are non-contact sensors that detect the opening and closing of the optical path from the light-emitting element to the light-receiving element. Photointerrupter S1 is an example of the "sensor for detecting the presence or absence of a sheet being fed by a feeding roller" of the present invention.

[0163] The shutter 39C of the actuator 39 blocks the optical path of the photointerrupter S1. When the contact portion 39B is pressed against the sheet SH being fed by the feed roller 21, the shutter 39C opens the optical path of the photointerrupter S1. As a result, the photointerrupter S1 detects the presence or absence of the sheet SH being fed by the feed roller 21.

[0164] The shutter 38C of the lower actuator 38 blocks the optical path of the photointerrupter S2. When the contact portion 37B of the upper actuator 37 is pressed against the sheet SH supported by the support plate 31, the shutter 38C of the lower actuator 38 opens the optical path of the photointerrupter S2. As a result, the photointerrupter S2 detects the presence or absence of the sheet SH supported by the support plate 31.

[0165] As shown in Figure 13, the wire harness W1 is a bundle of signal wiring extending from the sensor board B1 and transmitting detection signals from the photointerrupters S1 and S2. A male connector located at one end of the wire harness W1 is mated with a female connector on the sensor board B1. The wire harness W1 extends in the other direction in the width direction so as to move away from the sensor board B1.

[0166] As shown in Figure 12, the wire harness W1 is routed in the vicinity of the side surface 90S2 to the rear side of the rear wall 94. The rear side of the rear wall 94 is an example of the "rear side facing the second roller side in the unit frame".

[0167] The first feeding frame 90 has a harness holding portion 90W. The harness holding portion 90W consists of multiple protrusions and plate-like pieces formed along the lower end of the rear wall 94 on the back surface of the rear wall 94. The harness holding portion 90W supports the wire harness W1 from below with each protrusion, and restricts the wire harness W1 from moving rearward from the back surface of the rear wall 94 with each plate-like piece.

[0168] The harness holding section 90W holds the wire harness W1 that has been routed to the rear side of the rear wall 94, and holds the wire harness W1 along the rear side of the rear wall 94 to a position closer to one side than the center CL1 in the width direction of the unit frame 100F, that is, to the vicinity of the drive frame 80. The harness holding section 90W holds the wire harness W1 before assembling the feeding unit 100 to the first side frame 9L and the second side frame 9R.

[0169] After the supply unit 100 is assembled to the first side frame 9L and the second side frame 9R, the other end of the wire harness W is routed as indicated by arrow Y4. Although not shown in the illustration, the other end of the wire harness W is connected to the relay board on the side of the first side frame 9L facing one side in the width direction.

[0170] <Effects and Effects> In the image forming apparatus 1 of the embodiment, as shown in Figure 1, the unit frame 100F supports the feeding roller 21 and the separation roller 22 by the second feeding frame 29.

[0171] As shown in Figures 4 and 5, the first side frame 9L and the second side frame 9R have guides 9L2 and 9R2 that guide the drawer 2D.

[0172] As shown in Figures 3 to 5, the first end 80L and the second end 90R of the unit frame 100F are fastened to the first side frame 9L and the second side frame 9R.

[0173] As a result, the image forming apparatus 1 can accurately position the feed roller 21 relative to the first roller 41. Furthermore, the image forming apparatus 1 can accurately position the feed roller 21 relative to the second roller 42, which is positioned relative to the first roller 41 by the positioning mechanism 8 shown in Figure 8.

[0174] Therefore, the image forming apparatus 1 of the embodiment can suppress positional displacement of the image formed on the sheet SH as it passes through the photosensitive drum 2G, with respect to the sheet SH fed by the feeding unit 100.

[0175] Furthermore, as shown in Figure 16, the image forming apparatus 1 is equipped with a motor M1 and a first drive train PS1. As shown in Figures 12 and 13, the unit frame 100F includes a drive frame 80 having a first end 80L that supports the transmission gears G2A to G2D, which are part of the first drive train PS1; a first feed frame 90 having a second end 90R; and a second feed frame 29 that rotatably supports the feed roller 21, as shown in Figure 1. As shown in Figure 6, the drive frame 80 is fastened to the first feed frame 90 in a manner aligned with the first feed frame 90 and the second feed frame 29 in the width direction. This configuration allows for reliable transmission of driving force to the feed roller 21 and suppresses the generation of abnormal noise.

[0176] Furthermore, the image forming apparatus 1 includes a support plate 31 shown in Figure 9, a lifting mechanism 6 shown in Figures 13 to 15, and a second drive row PS2 shown in Figures 14 and 15. As shown in Figure 15, the first feed frame 90 has a second end 90R and supports a metal shaft 61 and a driven cam 60, which are part of the second drive row PS2, and the lifting mechanism 6. As shown in Figure 1, the second feed frame 29 supports the feed roller 21. As shown in Figure 14, the drive frame 80 supports the drive cam C2, which is another part of the second drive row PS2, and as shown in Figure 6, it is fastened to the first feed frame 90 in a state aligned with the first feed frame 90 in the width direction. The second feed frame 29 is fastened to the first feed frame 90 in a state aligned with the first feed frame 90 in the vertical direction. With this configuration, the driving force can be reliably transmitted to the feed roller 21 and the lifting mechanism 6, and the generation of abnormal noise can be reliably suppressed. Furthermore, it allows for easy assembly of the unit frame 100F and increases the rigidity of the unit frame 100F.

[0177] Furthermore, in this image forming apparatus 1, as shown in Figure 1, the feeding unit 100 has a separation roller 22, a separation pad 22A, and a sheet guide 89. As shown in Figures 11 and 13, the first feeding frame 90 has a second end 90R that supports the separation pad 22A and the sheet guide 89. As shown in Figure 1, the second feeding frame 29 supports the feeding roller 21 and the separation roller 22. As shown in Figure 6, the drive frame 80 is fastened to the first feeding frame 90 in a manner aligned with the first feeding frame 90 in the width direction. The second feeding frame 29 is fastened to the first feeding frame 90 in a manner aligned with the first feeding frame 90 in the vertical direction. This configuration allows for easy assembly of the unit frame 100F and increases the rigidity of the unit frame 100F.

[0178] Furthermore, in this image forming apparatus 1, as shown in Figure 16, the gear tooth height H1 of the first transmission gear G1 and the second transmission gear G2 is greater than the gear tooth height H2 of the other transmission gears G2A to G2D, G2F, etc. in the first drive train PS1. With this configuration, even if the meshing depth between the first transmission gear G1 and the second transmission gear G2 tends to vary due to the fastening of the first end 80L to the first side frame 9L, vibrations and noise caused by these variations in meshing depth can be reduced by the high-tooth gears of the first transmission gear G1 and the second transmission gear G2.

[0179] Furthermore, in this image forming apparatus 1, the range A1 in which the first transmission gear G1 and the second transmission gear G2 mesh in the vertical direction overlaps with at least a portion of the range A2 in which the positioning boss 9L1 exists in the vertical direction. With this configuration, the first transmission gear G1 and the second transmission gear G2 mesh at a position close in the vertical direction to the positioning boss 9L1 that positions the unit frame 100F relative to the first side frame 9L, thereby suppressing variations in the meshing depth between the first transmission gear G1 and the second transmission gear G2.

[0180] Furthermore, in the image forming apparatus 1, as shown in Figure 13, the sensor substrate B1 has photointerrupters S1 and S2. The substrate support section 90B supports the sensor substrate B1 before assembling the feeding unit 100 to the first side frame 9L and the second side frame 9R. As shown in Figure 12, the harness holding section 90W holds the wire harness W1 before assembling the feeding unit 100 to the first side frame 9L and the second side frame 9R. This configuration eliminates the need to support the sensor substrate B1 with the feeding unit 100 or to hold the wire harness W1 with the feeding unit 100 after the feeding unit 100 has been assembled to the first side frame 9L and the second side frame 9R.

[0181] Furthermore, in this image forming apparatus 1, as shown in Figure 14, the substrate support portion 90B supports the sensor substrate B1 at a position closer to the other side than the center CL1 in the width direction of the unit frame 100F. As shown in Figure 12, the harness holding portion 90W formed on the back surface of the rear wall 94 holds the wire harness W1 routed from the sensor substrate B1 to the back surface of the rear wall 94, and holds the wire harness W1 along the back surface of the rear wall 94 to a position closer to the one side than the center CL1 in the width direction of the unit frame 100F. With this configuration, the space for arranging the sensor substrate B1 and the wire harness W1 can be effectively utilized without interfering with other components constituting the feeding unit 100.

[0182] Furthermore, in this image forming apparatus 1, as shown in Figures 3 to 5, the insertion direction of the screws 80F1 and 80F2 for fastening the first end 80L to the first side frame 9L and the insertion direction of the screws 90F1 and 90F2 for fastening the second end 90R to the second side frame 9R are the same direction, and proceed from front to back along the transport direction DT1. With this configuration, the feed roller 21 can be positioned with even greater precision relative to the first roller 41 compared to the case where the insertion directions of the screws 80F1, 80F2, 90F1, and 90F2 are different for the first end 80L and the second end 90R.

[0183] Furthermore, in this image forming apparatus 1, as shown in Figure 2, with the cover 9F open the drawer opening 9H, the upper fastening of the first end 80L to the first side frame 9L and the upper fastening of the second end 90R to the second side frame 9R can be released. With this configuration, during the replacement of the feeding unit 100, the worker can easily release and remove the upper fastenings of the first end 80L and the second end 90R by operating the cover 9F to open the drawer opening 9H, and as a result, the subsequent assembly and fastening can also be easily performed.

[0184] Although the present invention has been described above with reference to examples, it goes without saying that the present invention is not limited to the above examples and can be applied with appropriate modifications without departing from its spirit.

[0185] In the embodiments, the image forming apparatus of the present invention was embodied as image forming apparatus 1, but the present invention is not limited to this configuration. For example, the configuration of the present invention may be applied to a multifunction device equipped with an image forming function and an image reading function.

[0186] The photointerrupters S1 and S2 in this embodiment may be replaced with sensors of other detection methods, such as non-contact sensors using magnetism or electromagnetic induction, or contact sensors.

[0187] The lifting mechanism 6 in the embodiment is configured to move the support plate 31 up and down to bring it closer to and further away from the feed roller 21, but the present invention is not limited to this configuration. For example, a configuration in which the lifting mechanism 6 is modified to move the feed roller 21 up and down to bring the support plate 31 closer to and further away from the feed roller 21 is also included in the present invention. [Explanation of Symbols]

[0188] 1…Image forming apparatus, 9…Apparatus body 2D...drawer, X1...rotation axis 2G...Photosensitive drum, SH...Sheet DT1... Conveying direction, 41... First roller 42...Second roller, 100...Feeding unit 21...Feed roller, 8...Positioning mechanism 9L…First side frame, 9R…Second side frame 9L2, 9R2… Guide, 100F… Unit frame 80L...first end, 90R...second end M1...Motor, PS1...First drive train, 80...Drive frame 90, 29... feed frames (90... 1st feed frame, 29... 2nd feed frame) 31...Support plate, 6...Lifting mechanism, PS2...Second drive train 22...Separation roller, 22A...Separation pad 89B... Guide surface, 89H... Opening for pad 89...Seat guide, G1...First transmission gear, G2...Second transmission gear H1...Height of the gear teeth of the first and second transmission gears. H2... The height of the gear teeth of the transmission gears other than the second transmission gear in the first drive train. 9L1…Positioning boss A1... The range in which the first transmission gear and the second transmission gear mesh in the vertical direction. A2... Range where a positioning boss exists in the vertical direction S1...Sensor (photointerrupter), B1...Sensor board W1...Wire harness, 90B...Circuit board support 90W…Harness retaining part CL1...Center in the width direction of the unit frame 9H...Opening for drawer, 9F...Cover

Claims

1. The main body of the device, A drawer that is mounted on the main body of the device and is movable to an exposed position where at least a portion of it is located outside the main body of the device, A photosensitive drum supported in the drawer so as to be rotatable about a rotation axis extending in the width direction, A first roller is rotatably supported in the drawer and conveys the sheet toward the photosensitive drum in the conveying direction, A second roller is rotatably supported on the main body of the device and faces the first roller, A feeding unit mounted on the main body of the apparatus, located upstream of the first and second rollers in the conveying direction, the feeding unit having a feeding roller that feeds a sheet from outside the main body of the apparatus toward the first and second rollers, A positioning mechanism for positioning the second roller relative to the first roller while the drawer is in the mounting position, An image forming apparatus comprising, The device body has a first side frame located on one side in the width direction relative to the drawer, and a second side frame located on the other side in the width direction relative to the drawer. The first side frame and the second side frame have guides for guiding the drawer as it moves between the mounting position and the exposed position. The feeding unit is a unit frame that supports the feeding roller, and the image forming apparatus is characterized in that the unit frame has a first end located on one side in the width direction fastened to the first side frame, and a second end located on the other side in the width direction fastened to the second side frame.

2. A motor that generates driving force, A first drive train that transmits the driving force of the motor to the feed roller, Equipped with, The unit frame comprises a drive frame having the first end and supporting at least a portion of the first drive row, and a feed frame having the second end and rotatably supporting the feed roller, The image forming apparatus according to claim 1, wherein the drive frame is fastened to the feed frame in a manner aligned with the feed frame in the width direction.

3. A support plate that supports the sheet to be fed by the feeding roller on the outside of the main body of the device, A lifting mechanism that moves the support plate closer to and further away from the feed roller, A second drive train that branches off from the first drive train and transmits the driving force to the lifting mechanism, Equipped with, The feeding frame comprises a first feeding frame having the second end and supporting a part of the second drive row and the lifting mechanism, and a second feeding frame supporting the feeding roller, The drive frame supports the other part of the second drive row and is fastened to the first feed frame in a manner aligned with the first feed frame in the width direction. The image forming apparatus according to claim 2, wherein the second feeding frame is fastened to the first feeding frame in a manner that is aligned vertically with the first feeding frame.

4. The feeding unit comprises a separation roller and a separation pad that face each other in the vertical direction and separate the sheets fed by the feeding roller, and a sheet guide that has a guide surface for guiding the sheets fed by the feeding roller and exposes the separation pad from the guide surface through a pad opening. The feeding frame comprises a first feeding frame having the second end and supporting the separation pad and the seat guide, and a second feeding frame supporting the feeding roller and the separation roller, The drive frame is fastened to the first feed frame in a manner aligned with the first feed frame in the width direction. The image forming apparatus according to claim 2, wherein the second feeding frame is fastened to the first feeding frame in a manner that is aligned vertically with the first feeding frame.

5. The first side frame supports the first transmission gear that transmits the driving force to the first drive train, The first drive train has a second transmission gear that meshes with the first transmission gear, The image forming apparatus according to any one of claims 2 to 4, wherein the height of the gear teeth of the first transmission gear and the second transmission gear is greater than the height of the gear teeth of the transmission gears other than the second transmission gear in the first drive train.

6. The first side frame has positioning bosses for positioning the unit frame relative to the first side frame, The image forming apparatus according to claim 5, wherein the range in which the first transmission gear and the second transmission gear mesh in the vertical direction overlaps with at least a portion of the range in which the positioning boss exists in the vertical direction.

7. A sensor substrate having a sensor for detecting the presence or absence of a sheet being fed by the feeding roller, A wire harness extending from the sensor substrate and transmitting the detection signal of the sensor, Equipped with, The image forming apparatus according to claim 1 or 2, wherein the unit frame has a substrate support portion for supporting the sensor substrate before assembling the feeding unit to the main body of the apparatus, and a harness holding portion for holding the wire harness before assembling the feeding unit to the main body of the apparatus.

8. The substrate support portion supports the sensor substrate at a position closer to the other side than the center in the width direction of the unit frame. The harness holding portion is formed on the back surface of the unit frame facing the second roller side, The image forming apparatus according to claim 7, wherein the harness holding portion is configured to hold the wire harness routed from the sensor substrate to the back surface, and to hold the wire harness along the back surface to a position closer to one side than the center in the width direction of the unit frame.

9. The image forming apparatus according to claim 1 or 2, wherein the direction of insertion of the screw for fastening the first end to the first side frame and the direction of insertion of the screw for fastening the second end to the second side frame are the same direction and are in line with the transport direction.

10. The device body has a cover that opens and closes a drawer opening through which the drawer moves from the mounting position to the exposed position, The image forming apparatus according to claim 1 or 2, wherein the upper fastening of the first end to the first side frame and the upper fastening of the second end to the second side frame can be released when the cover has opened the drawer opening.

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