Paper feeding device and image forming apparatus

Abstract

To facilitate the replacement of the separation roller. [Solution] The paper feeding device comprises a paper feeding roller 221 for transporting sheets, a separation roller 161 which is detachable from the device body and is located in a normal operating position facing the paper feeding roller 221 when mounted on the device body, and a push-up projection 169 and a torsion coil spring 177 which push the separation roller 161 in the normal operating position in the removal direction when the separation roller 161 is removed from the device body.

Description

Technical Field

[0001] The present invention relates to a paper feeding device and an image forming apparatus, and more particularly to a paper feeding device for conveying sheets such as paper and an image forming apparatus provided with such a paper feeding device.

Background Art

[0002] An image forming apparatus includes a paper feeding device that accommodates a plurality of sheets in a stacked state, and forms an image on each sheet supplied one by one from the paper feeding device. The paper feeding device conveys the sheets one by one in order from the uppermost sheet of the plurality of sheets.

[0003] For example, in Japanese Patent Application Laid-Open No. 2016-155670, a paper feeding unit that conveys sheets one by one by the cooperation of a paper feeding member and an anti-duplication unit, and a guide surface that guides the sheets conveyed by the paper feeding unit are recessed. A guide unit including a housing unit, and the anti-duplication unit includes a holder detachably accommodated in the housing unit, and a separation member supported by the holder and separating the overlapping sheets. The holder includes a holder main body in which a displaceable portion that can be elastically deformed is formed at a position separated from the support position of the separation member toward the downstream side in the sheet conveyance direction, an engaging portion provided at the displaceable portion and rotatably connected to the side wall of the housing unit, and an operation portion extending from the displaceable portion toward the downstream side in the sheet conveyance direction. When the displaceable portion is elastically deformed toward the separation member side through the operation portion, a conveyance device is described in which the connection between the side wall and the engaging portion is released.

[0004] However, in the conveying device described in Japanese Patent Publication No. 2016-155670, the connection between the side wall of the housing recessed in the guide surface and the engaging portion is released when the displacement portion is elastically deformed toward the separation member side via the operating portion. For this reason, it is necessary to apply force to the displacement portion in order to elastically deform it until the engaging portion no longer engages with the side wall. Since the displacement portion is formed at a position away from the support position of the separation member on the downstream side in the conveying direction of the sheet, it elastically deforms with the support position of the separation member as the fulcrum. For this reason, since the holder elastically deforms at the support position of the separation member, there is a risk that the support position of the separation member may fluctuate. Therefore, it is desirable to remove the separation member without elastically deforming the holder. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-155670 [Overview of the project] [Problems that the invention aims to solve]

[0006] One of the objectives of this invention is to provide a paper feeding device that facilitates the replacement of the separation roller.

[0007] Another object of this invention is to provide an image forming apparatus that facilitates the replacement of separation rollers. [Means for solving the problem]

[0008] According to one aspect of this invention, the paper feeding device comprises a paper feeding roller for transporting sheets, a separation roller that is detachable from the device body and is located in a normal operating position facing the paper feeding roller when mounted on the device body, and an extrusion unit that pushes the separation roller in the normal operating position in the removal direction when the separation roller is removed from the device body.

[0009] According to another aspect of this invention, the image forming apparatus comprises the above-mentioned paper feeding device and an image forming unit that forms an image on a sheet conveyed by a paper feeding roller. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing the appearance of an MFP in one embodiment of the present invention. [Figure 2] This is a schematic side view showing part of the internal configuration of an MFP. [Figure 3] This figure shows an example of a pickup mechanism. [Figure 4] This is a perspective view showing a part of the MFP. [Figure 5] This is a perspective view of the separation unit. [Figure 6] This is a perspective view of the separation holder. [Figure 7] This is a view of the separation unit from the front, with the separation roller in its normal operating position. [Figure 8] This is a view of the separation unit from the front, with the separation roller in the removal position. [Figure 9] This is a perspective view showing the paper feed roller unit in an upward position. [Figure 10] This is a perspective view showing an example of the paper feed roller being removed from the holding holder. [Figure 11] This is a view of the separation unit in the modified example, seen from the front. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In the following description, identical parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions of them will not be repeated.

[0012] Figure 1 is a perspective view showing the appearance of an MFP in one embodiment of the present invention. The MFP (Multi Function Peripheral) 100 is an example of an image forming apparatus. In Figure 1, the X, Y, and Z directions are defined as being orthogonal to each other. The X and Y directions are parallel to the horizontal plane. In the following description, the X direction is the direction parallel to the left and right of the MFP 100, and is also called the left-right direction. The direction of the arrow in the X direction is to the right, and the direction opposite to the arrow in the X direction is to the left. The Y direction is the direction parallel to the depth direction of the MFP 100, and is also called the front-back direction. The direction opposite to the arrow in the Y direction is the front, and the direction of the arrow in the Y direction is the back. The Z direction is the direction parallel to the up and down direction of the MFP 100, and is also called the up and down direction. The direction in which the arrow in the Z direction points is up, and the direction opposite to the arrow in the Z direction is down.

[0013] Referring to Figure 1, the MFP100 has a housing 11 that covers the entire MFP100. The housing 11 has an internal space in which an image forming unit 140 that forms an image on a sheet of paper or the like based on image data and a paper feed device 150 that supplies paper to the image forming unit 140 are arranged. The MFP100 also has a side door 11A on the left side of the housing 11. The side door 11A can be opened and closed. When the side door 11A is open, the left side of the internal space of the housing 11 is open to the outside. When the side door 11A is closed, the internal space of the housing 11 is not open to the outside.

[0014] FIG. 2 is a side view schematically showing a partial internal configuration of the MFP. Referring to FIG. 2, inside the MFP 100, a main conveyance path 41 indicated by a thick dotted line is formed to extend basically in the vertical direction. The main conveyance path 41 is a path for guiding the paper conveyed from the paper feeding device 150 through the image forming unit 140 to the paper discharge tray 159. In the main conveyance path 41 of this example, a lower end portion 43 on the opposite side of the upper end portion 13 located above the image forming unit 140 constitutes an entrance for receiving paper from the paper feeding device 150. Also, the upper end portion 13 of the main conveyance path 41 constitutes an exit for discharging the paper after image formation to the paper discharge tray 159. A paper discharge roller 15 is provided at the upper end portion 13 of the main conveyance path 41. The lower end portion 43 of the main conveyance path 41 is connected to a plurality of sub-conveyance paths 151a, 152a, 153a of the paper feeding device 150 described later.

[0015] The paper feeding device 150 includes four paper feeding trays 151, 152, 153, 154. Two paper feeding trays 151, 152 are stacked and arranged in a state of being arranged one above the other in this order from above downward. Below the paper feeding tray 152, two paper feeding trays 153, 154 are arranged. The two paper feeding trays 153, 154 are arranged side by side in the left-right direction.

[0016] As shown by a thick dashed line in FIG. 2, in the paper feeding device 150, a sub-conveyance path 151a extending from the paper feeding tray 151 located in the upper stage among the four paper feeding trays 151, 152, 153, 154 to the lower end portion 43 of the main conveyance path 41 is formed. Three sub-conveyance paths 152a, 153a, 154a extending from the three paper feeding trays 152, 153, 154 to the lower end portion 43 of the main conveyance path 41 are formed. Portions of a predetermined length from the lower end portion 43 of the main conveyance path 41 of the three sub-conveyance paths 152a, 153a, 154a are shared by the three sub-conveyance paths 152a, 153a, 154a. Also, a part of the sub-conveyance path 153a is shared by the sub-conveyance path 154a.

[0017] For each of the four paper feed trays 151, 152, 153, and 154, a pick-up roller 211, a paper feed roller 221, and a separation roller 161 are provided. The pick-up roller 211, the paper feed roller 221, and the separation roller 161 provided corresponding to the paper feed tray 151 are provided in the sub conveyance path 151a. The pick-up roller 211, the paper feed roller 221, and the separation roller 161 provided corresponding to the paper feed tray 152 are provided in the sub conveyance path 152a. The pick-up roller 211, the paper feed roller 221, and the separation roller 161 provided corresponding to the paper feed tray 153 are provided in the sub conveyance path 153a. The pick-up roller 211, the paper feed roller 221, and the separation roller 161 provided corresponding to the paper feed tray 154 are provided in the sub conveyance path 154a.

[0018] In the MFP 100, at the time of image formation, the tray in which the paper to be image-formed is accommodated is selected as the target tray from among the four paper feed trays 151, 152, 153, and 154. The pick-up roller 211, the paper feed roller 221, and the separation roller 161 corresponding to the tray selected as the target tray among the four paper feed trays 151, 152, 153, and 154 operate. Thereby, the paper is supplied from the tray selected as the target tray to the main conveyance path 41 through any one of the sub conveyance paths 151a, 152a, 153a, and 154a.

[0019] The image forming unit 140 includes image forming units 21Y, 21M, 21C, and 21K for yellow, magenta, cyan, and black respectively. When at least one of the image forming units 21Y, 2;1M, 21C, and 21K is driven, an image is formed on the paper. When all of the image forming units 21Y, 21M, 21C, and 21K are driven, a full-color image is formed. Print data for yellow, magenta, cyan, and black are input to the image forming units 21Y, 21M, 21C, and 21K respectively. Since only the colors of the toners handled by the image forming units 21Y, 21M, 21C, and 21K are different, here, the image forming unit 21Y for forming a yellow image will be described.

[0020] The image forming unit 21Y includes an exposure head that receives yellow printing data, a photosensitive drum, a charging charger, a developer, and a transfer roller 23Y. The exposure head emits laser light according to the received printing data (electrical signal). The emitted laser light is scanned in one dimension by a polygon mirror on the exposure head, exposing the photosensitive drum. The direction in which the photosensitive drum is scanned in one dimension is the main scanning direction. After the photosensitive drum is charged by the charging charger, it is irradiated with laser light emitted by the exposure head. This forms an electrostatic latent image on the photosensitive drum. Subsequently, the developer places toner on the electrostatic latent image to form a toner image. The toner image formed on the photosensitive drum is transferred onto the intermediate transfer belt 27 by the transfer roller 23Y.

[0021] Meanwhile, the intermediate transfer belt 27 is suspended by the drive roller 24 and roller 24A to prevent slack. When the drive roller 24 rotates counterclockwise in the figure, the intermediate transfer belt 27 rotates counterclockwise in the figure at a predetermined speed. As the intermediate transfer belt 27 rotates, roller 24A rotates counterclockwise.

[0022] As a result, the image forming units 21Y, 21M, 21C, and 21K sequentially transfer toner images onto the intermediate transfer belt 27. The timing at which each of the image forming units 21Y, 21M, 21C, and 21K transfers toner images onto the intermediate transfer belt 27 is adjusted by detecting reference marks attached to the intermediate transfer belt 27. In this way, yellow, magenta, cyan, and black toner images are superimposed on the intermediate transfer belt 27.

[0023] In the main transport path 41, a timing roller 45, a transfer roller 47, and a fixing roller 49 are arranged in that order at intervals from the lower end 43 to the upper end 13. Paper supplied from the paper feed device 150 to the main transport path 41 is sent to the timing roller 45.

[0024] The timing roller 45 adjusts the paper transport state in the main transport path 41 so that the paper reaches the transfer roller 47 at the same time that the toner image formed on the intermediate transfer belt 27 reaches the transfer roller 47. The paper transported by the timing roller 45 is pressed against the intermediate transfer belt 27 by the transfer roller 47. By charging the transfer roller 47, the yellow, magenta, cyan, and black toner images superimposed on the intermediate transfer belt 27 are transferred to the paper. The amount of charge on the transfer roller 47 is adjusted to a value suitable for the paper weight by controlling the voltage applied to the transfer roller 47 by the CPU (Central Processing Unit).

[0025] The paper onto which the toner image has been transferred is transported to the fuser roller 49, where it is heated. This melts the toner and fixes it to the paper. After the image is formed, the paper is discharged onto the output tray 159 from the upper end 13 of the main transport path 41 by the output roller 15. The temperature of the fuser roller 49 is controlled by the CPU and adjusted to a value suitable for the paper weight.

[0026] The paper feeder 150 is equipped with three paper trays 151, 152, and 153. Each of the three paper trays 151, 152, and 153 has the same pickup mechanism that supplies the top sheet of paper from among the multiple sheets of paper contained in it to the main transport path 41. Here, the pickup mechanism will be explained using paper tray 153 as an example.

[0027] Figure 3 shows an example of a pickup mechanism. Figure 3 shows a cross-section of the MFP100 in a plane perpendicular to the front-to-back direction. Referring to Figure 3, the paper feed roller unit 200 is positioned on the upper side of the paper feed tray 153.

[0028] The paper feed roller unit 200 includes a holding holder 201, a pick roller 211, and a paper feed roller 221. The pick roller 211 is mounted on the shunting shaft 213 in a rotatable manner. The paper feed roller 221 is mounted on the paper feed shaft 223 in a rotatable manner around the axis of the paper feed shaft 223. The shunting shaft 213 and the paper feed shaft 223 are pivotally supported by the holding holder 201. The paper feed shaft 223 is pivotally supported by the housing 11. The paper feed roller unit 200 is fixed to the housing 11 by the paper feed shaft 223. The holding holder 201 is rotatable around the axis of the paper feed shaft 223. The holding holder 201 is biased by an elastic member such as a spring in the rotational direction in which the shunting shaft 213 of the pick roller 211 rotates downward.

[0029] The paper feed tray 151 has a lifting plate 158 at its bottom. Multiple sheets of paper P are placed on the lifting plate 158 in an overlapping state. As the lifting plate 158 rises, the top surfaces of the multiple sheets of paper P come into contact with the pick roller 211.

[0030] As the lifting plate 158 rises further from the state where the top surfaces of multiple sheets of paper P are in contact with the pick roller 211, the pick roller 211 rises, overcoming the elastic force of the elastic member. A sensor is provided to measure the height of the pick roller 211, and when the pick roller 211 reaches a predetermined height, the lifting plate 158 stops rising. As a result, with the pick roller 211 in contact with the top surface of the paper P, the pick roller 211 pushes the paper P downward with a predetermined force. In this state, as the pick roller 211 rotates, the top sheet of paper P is transported toward the paper feed roller 221 by the frictional force generated between it and the pick roller 211.

[0031] The paper feed tray 153 has a side wall 153A that partitions the left side of the storage space 157. The side wall 153A has a surface perpendicular to the left-right direction. The transport guide 155 is located above the storage space 157, on the left side. The transport guide 155 has a horizontal surface and connects to the side wall 153A. The transport guide 155 is part of the paper feed tray 153 and is located above the paper feed tray 154. The transport guide 155 has an upper surface and constitutes part of the secondary transport path 153a.

[0032] A separation unit 160 is positioned below the paper feed roller unit 200. The separation unit 160 includes a separation roller 161 and a swing holder 171. The separation unit 160 is positioned to the left of the side wall 153A of the paper feed tray 153. The majority of the separation unit 160 is positioned below the transport guide 155. The transport guide 155 has an opening 155A formed in the portion corresponding to the upper part of the separation unit 160. A portion of the separation roller 161 is positioned above the transport guide 155 through the opening 155A.

[0033] The separation roller 161 is rotatable around the separation shaft 165. The separation shaft 165 is supported by a pivot holder 171. The pivot holder 171 is mounted on the housing 11 in a manner that allows it to rotate around the axis of the pivot shaft 173. The pivot holder 171 is supported by the housing 11 on the pivot shaft 173. The lower bottom surface of the pivot holder 171 is in contact with a compression spring 175. The upper end of the compression spring 175 is in contact with the bottom surface of the separation holder 167, and the lower end is fixed to the housing 11. The compression spring 175 biases the pivot holder 171 upward. This causes the pivot holder 171 to rotate around the axis of the pivot shaft 173, pushing the separation roller 161 upward.

[0034] The separation roller 161 is positioned opposite the paper feed roller 221. When there is no paper between the paper feed roller 221 and the separation roller 161, the separation roller 161 is in contact with the paper feed roller 221 and rotates in conjunction with the rotation of the paper feed roller 221. However, the separation shaft 165 of the separation roller 161 is provided with a limiter 163 (see Figure 5) that restricts the rotation of the separation roller 161.

[0035] In some cases, two or more sheets of paper are stacked and removed from the paper tray 151 by the pick roller 211. In this case, the stack of two or more sheets of paper enters between the paper feed roller 221 and the separation roller 161. The top sheet of the stack of two or more sheets comes into contact with the paper feed roller 221, and the bottom sheet comes into contact with the separation roller 161. Here, we will explain using the case where two sheets of paper P1 and P2 are stacked as an example. Let μ1 be the coefficient of dynamic friction between the paper feed roller 221 and the top sheet of paper P1, μ2 be the coefficient of static friction between the separation roller 161 and the bottom sheet of paper P2, and μ3 be the coefficient of static friction between the top sheet of paper P1 and the bottom sheet of paper P2. The outer surfaces of the paper feed roller 221 and the separation roller 161 are made of a material that satisfies the relationships μ1 > μ3 and μ2 > μ3, and are surface-treated.

[0036] When multiple sheets of paper P1 and P2 are positioned between the feed roller 221 and the separation roller 161, a resistance is provided on the separation shaft 165 to restrict the rotation of the separation roller 161, resulting in a force being generated on the paper P2 in the direction opposite to the transport direction. Since μ2 > μ3, the separation roller 161 stops without rotating while in contact with the paper P2. Also, since μ1 > μ3, the frictional force that paper P1 receives from the feed roller 221 overcomes the frictional force that paper P1 receives from paper P2, and paper P1 is transported upwards towards the transport guide 155 by the feed roller 221.

[0037] Figure 4 is a perspective view showing a part of the MFP. The MFP 100 shown in Figure 4 includes paper feed trays 153 and 154, with the paper feed tray 153 shown extended forward from the housing 11. The paper feed tray 153 has a storage space 157 and a transport guide 155. The storage space 157 is a space for storing sheets. The paper feed tray 153 has a side wall 153A that demarcates the left side of the storage space 157. The side wall 153A has a surface perpendicular to the left-right direction. The transport guide 155 is located above the storage space 157 and to the left of the side wall 153A. The transport guide 155 is connected to the side wall 153A. The transport guide 155 constitutes part of the transport path through which the sheets are transported.

[0038] The paper feed roller unit 200 is positioned above the storage space 157 and the separation unit 160. The separation unit 160 is located below the separation roller 161 of the paper feed roller unit 200. The separation roller 161 and the paper feed roller 221 come into contact through an opening 155A formed in the transport guide 155.

[0039] With the paper feed tray 153 pulled out to the front, the paper feed roller unit 200 and the transport guide 155 are exposed to the outside of the housing 11. Therefore, the user can access the paper feed roller unit 200 from above.

[0040] Figure 5 is a perspective view of the separation unit. Referring to Figure 5, the separation unit 160 includes a swing holder 171 and a separation holder 167. The swing holder 171 has a first front wall 171A, a first rear wall 171B, and a first connecting portion 171C. The two first front walls 171A and the first rear wall 171B are positioned opposite each other. The first connecting portion 171C connects the first front wall 171A and the first rear wall 171B. The swing holder 171 has a first internal space enclosed by the first front wall 171A, the first rear wall 171B, and the first connecting portion 171C. The first internal space is open upwards. The separation holder 167 is housed in the first internal space of the swing holder 171. The first front wall 171A and the first rear wall 171B each support the separation shaft 165 in a rotatable manner.

[0041] The oscillating holder 171 has an oscillating shaft 173. The oscillating shaft 173 extends in the front-rear direction. The oscillating shaft 173 is pivotally supported by the housing 11 in a rotatable state. The oscillating holder 171 contacts a compression spring 175 at a predetermined distance from the oscillating shaft 173 on its bottom surface. The upper end of the compression spring 175 contacts the bottom surface of the separation holder 167, and the lower end is fixed to the housing 11. The compression spring 175 expands and contracts in a direction intersecting the axial direction of the oscillating shaft 173. Here, the compression spring 175 biases the oscillating holder 171 upward. This causes the oscillating holder 171 to rotate around the axis of the oscillating shaft 173.

[0042] Figure 6 is a perspective view of the separation holder. The separation holder 167 has a second front wall 167A, a second rear wall 167B, and a second connecting portion 167C. The second front wall 167A and the second rear wall 167B are positioned opposite each other. The second connecting portion 167C connects the second front wall 167A and the second rear wall 167B. The separation holder 167 has a second internal space enclosed by the second front wall 167A, the second rear wall 167B, and the second connecting portion 167C. The second front wall 167A and the second rear wall 167B each support the separation shaft 165 in a non-rotatable state.

[0043] The separation roller 161 and limiter 163 are connected to the separation shaft 165 between the second front wall 167A and the second rear wall 167B. The separation roller 161 and limiter 163 are housed in the second internal space of the separation holder 167 without contacting the second connecting portion 167C. The separation roller 161 is rotatably connected to the separation shaft 165. The limiter 163 has an inner ring and an outer ring. The inner ring is fixed to the separation shaft 165 in a non-rotatable manner. The outer ring is rotatable around the inner ring. The outer ring is connected to the separation roller 161. The outer ring receives a predetermined load from the inner ring in the rotational direction. Therefore, when the separation roller 161 receives an external force in the rotational direction, the separation roller 161 rotates around the separation shaft 165 if that external force is greater than or equal to a predetermined value. If the external force acting on the separation roller 161 is less than a predetermined value, the separation roller 161 will not rotate around the separation shaft 165. The predetermined value is determined by the magnitude of the load acting between the inner and outer rings of the limiter 163.

[0044] A portion of the separation shaft 165 protrudes from the second front side wall 167A of the separation holder 167. The portion of the separation shaft 165 that protrudes from the second front side wall 167A is the first projection. The separation holder 167 has an upward projection 169 that protrudes in a first direction parallel to the axial direction of the separation shaft 165, at a position away from the connection portion of the second front side wall 167A. The upward projection 169 is also called the second projection. The upward projection 169 protrudes forward from the second front side wall 167A at a position a predetermined distance below the separation shaft 165.

[0045] The second front side wall 167A of the separation holder 167 has an operating portion 162 that protrudes upward. The vertical distance between the end of the operating portion 162 and the separation shaft 165 is greater than or equal to a predetermined distance. The operating portion 162 is preferably shaped to be easily grasped by the user with two fingers. For example, the end of the operating portion 162 is a flat plate shape having an upper surface and a lower surface facing each other. The lower surface faces downward, and the upper surface faces upward. In this case, it becomes easy for the user to pinch the upper and lower surfaces with their fingers and push the lower surface upward.

[0046] The separation holder 167 is attached to the rocking holder 171 by being inserted into the first internal space of the rocking holder 171 from above. The relative position of the separation roller 161 with respect to the rocking holder 171 when the separation holder 167 is attached to the rocking holder 171 is called the normal operating position.

[0047] Figure 7 is a front view of the separation unit with the separation roller in its normal operating position. Referring to Figure 7, the upper part of the separation roller 161 is in contact with the paper feed roller 221. The separation roller 161 is in its normal operating position.

[0048] The first front side wall 171A of the oscillating holder 171 has a guide groove 179 formed therein, which has a shape extending in a second direction intersecting the first direction. The first direction is parallel to the axial direction of the separation shaft 165. The second direction is the direction in which the separation holder 167 can move relative to the oscillating holder 171. In this embodiment, the first direction is the front-rear direction, and the second direction is the up-down direction. One end of the guide groove 179 is open upward.

[0049] The guide groove 179 has a restricting surface 178A and a fixed surface 179A. The restricting surface 178A is a surface that is parallel to the first direction, intersects the second direction, and faces the removal direction. The removal direction is parallel to the second direction and is the direction in which the separation roller 161 moves away from the swing holder 171. Here, the removal direction is upward. The fixed surface 179A is provided at a predetermined distance below the restricting surface 178A. The fixed surface 179A is a surface that is parallel to the first direction, intersects the second direction, and faces in the opposite direction to the removal direction.

[0050] The guide groove 179 further has a first guide surface 178B and a second guide surface 179B. The first guide surface 178B is the surface facing the regulating surface 178A. The second guide surface 179B is the surface facing the fixed surface 179A.

[0051] The first front wall 171A has an upward-facing opening at its upper end where the guide groove 179 is formed. The separation holder 167 is attached to the oscillating holder 171 by being inserted into the first internal space of the oscillating holder 171 from above. When the separation holder 167 is attached to the oscillating holder 171, the push-up projection 169 and the separation shaft 165 enter the guide groove 179 formed in the oscillating holder 171 from above, and the push-up projection 169 and the separation shaft 165 are guided by the guide groove 179. Also, with the separation holder 167 attached to the oscillating holder 171, the oscillating holder 171 is biased upward by the compression spring 175. As a result, a downward force acts on the paper feed roller 221 fixed to the housing 11. Therefore, a force acts on the separation shaft 165 and the push-up projection 169 of the separation holder 167 in a direction toward the swing holder 171.

[0052] The first guide surface 178B faces the restricting surface 178A. As the first guide surface 178B faces the restricting surface 178A, the separation shaft 165 comes into contact with the restricting surface 178A due to the first guide surface 178B. Also, the second guide surface 179B faces the fixed surface 179A. As the second guide surface 179B faces the fixed surface 179A, the push-up projection 169 comes into contact with the fixed surface 179A due to the second guide surface 179B.

[0053] The separation shaft 165 is restricted from moving downward when it is in contact with the restricting surface 178A. The push-up projection 169 is restricted from moving upward when it is in contact with the fixed surface 179A. Therefore, the separation holder 167 is fixed in a position on the swing holder 171 with the separation shaft 165 in contact with the restricting surface 178A and the push-up projection 169 in contact with the fixed surface 179A. The fixed surface 179A is located on the upstream side in the sheet transport direction, which in this embodiment is the right side, of the two opposing surfaces of the guide groove 179. When the separation roller 161 receives frictional force from the sheet, the push-up projection 169 receives force in the direction toward the fixed surface 179A. Therefore, the separation holder 167 can maintain its position on the swing holder 171.

[0054] When the separation roller 161 is in its normal operating position, the separation shaft 165 abuts against the restricting surface 178A and the push-up projection 169 abuts against the fixed surface 179A. A torsion coil spring 177 is attached to the spring shaft 177A. One end of the torsion coil spring 177 is fixed in a hole formed in the oscillating holder 171. The other end of the torsion coil spring 177 abuts against the push-up projection 169. The push-up projection 169 is biased upward by the torsion coil spring 177. When the separation roller 161 is in its normal operating position, upward movement from the paper feed roller 221 located above it is restricted. Therefore, the separation roller 161 is in its normal operating position when the paper feed roller 221 is attached to the housing 11.

[0055] Figure 8 is a front view of the separation unit with the separation roller in the removal position. Referring to Figure 8, when the paper feed roller 221 is removed from the housing 11, the separation roller 161 is no longer subjected to a downward force from above. The push-up projection 169 receives an upward force from the torsion coil spring 177, causing the push-up projection 169 to move upward. Consequently, the separation holder 167 moves upward. The position of the separation roller 161 when the separation holder 167 has moved upward is the removal position. When the separation roller 161 is in the removal position, the operating section 162 is higher than when the separation roller 161 is in the normal use position.

[0056] Figure 9 is a perspective view showing the paper feed roller unit in an upward position. Referring to Figure 9, the retaining holder 201 rotates around the paper feed shaft 223, exposing the paper feed rollers 221 and 221 to the right. This allows the user to access the paper feed rollers 221 and 221 from the right. This makes it easy to remove the paper feed rollers 221 and 221 from the retaining holder 201.

[0057] Figure 10 is a perspective view showing an example of the paper feed roller being removed from the holding holder. Referring to Figure 10, when the pick roller 211 and the paper feed roller 221 are removed from the holding holder 201, a space is created above the separation unit 160. As a result, the separation roller 161 and the operating unit 162 move above the transport guide 155.

[0058] <Variation> In the embodiment described above, the separation unit 160 moves the separation roller 161 from the normal use position to the removal position by biasing the push-up projection 169 upward with a torsion coil spring 177. In the modified example, the separation unit 160A is provided with an eject lever 301 instead of the torsion coil spring 177.

[0059] Figure 11 is a front view of the separation unit in a modified example. Referring to Figure 11, the separation unit 160A is shown with the separation roller 161 in its normal operating position. The separation unit 160A in the modified example has an eject lever 301. The eject lever 301 is positioned between the oscillating holder 171 and the separation holder 167. The eject lever 301 is located in the first internal space of the oscillating holder 171 through an opening in the right-hand side wall of the oscillating holder 171. The eject lever 301 contacts the upper surface of the bottom of the oscillating holder 171 and the lower surface of the bottom of the separation holder 167, respectively. The eject lever 301 is long in the left-right direction and includes a wedge portion whose height gradually changes in the left direction. The wedge portion has the smallest height at its tip in the right direction and increases in height as it moves away from the tip.

[0060] When the user moves the eject lever 301 to the left, the eject lever 301 moves between the swing holder 171 and the separation holder 167. As a result, the distance between the swing holder 171 and the separation holder 167 becomes equal to the height of the eject lever 301, and the separation holder 167 moves upward from the swing holder 171 by a distance equivalent to the height of the eject lever 301.

[0061] Furthermore, a through-hole is formed in the side wall 153A of the paper feed tray 153 at a location corresponding to the eject lever 301, so that the user can access the eject lever 301 from the right. The eject lever 301 may also pass through this through-hole.

[0062] <Other variations> The second rear side wall 167B of the separation holder 167 may have an upward projection 169A that protrudes in the axial direction of the separation shaft 165 at a position away from the connection portion with the separation shaft 165. The upward projection 169A protrudes rearward from the second rear side wall 167B at a position a predetermined distance below the separation shaft 165.

[0063] In this case, a guide groove 179 formed on the first front wall 171A is formed on the first rear wall 171B of the swing holder 171, and a torsion coil spring 177 is attached to it.

[0064] <Summary of Embodiments> (Item 1) A paper feed roller for transporting sheets, A separation roller that is detachable from the main body of the device and is located in the normal operating position facing the paper feed roller when mounted on the main body of the device, A paper feeding device comprising: an extrusion unit that pushes the separation roller, which is in the normal operating position, in the removal direction when the separation roller is removed from the main body of the device.

[0065] In this configuration, when the separation roller is removed from the device body, the separation roller, which is normally in use, is pushed out in the removal direction. As a result, the separation roller is pushed out and moved in the removal direction, making it easier to remove. Consequently, a paper feeding device can be provided that facilitates the replacement of the separation roller.

[0066] (Item 2) Further comprising a support portion that supports the rotation axis of the separation roller, The paper feeding device according to claim 1, wherein the extrusion portion includes an elastic member that biases the support portion toward the removal direction.

[0067] In this configuration, the rotation axis of the separation roller is supported by the support section, and the support section is biased toward the removal direction by the elastic member included in the extrusion section. As a result, the separation roller, whose rotation axis is supported by the support section, is pushed out in the removal direction by the elastic member. Therefore, the separation roller can be pushed out in the removal direction with a simple configuration.

[0068] (Item 3) The main body that supports the support part, The separation roller further comprises a first projection and a second projection that protrude from the support portion in a first direction parallel to the rotation axis of the separation roller, The paper feeding device according to claim 2, wherein the main body has a shape that extends in a second direction parallel to the removal direction and has guide grooves that guide the first projection and the second projection.

[0069] In this configuration, the first and second projections protrude from the support portion, which is supported by the main body, in a first direction parallel to the rotation axis of the separation roller, and are guided by guide grooves that extend in a second direction parallel to the removal direction of the main body. As a result, the support portion can be moved in the second direction relative to the main body.

[0070] (Item 4) The paper feed device according to item 3, wherein the elastic member is fixed to the main body and biases at least one of the first projection and the second projection in the removal direction.

[0071] In this configuration, the elastic member is fixed to the main body and biases at least one of the first projection and the second projection in the removal direction, thereby allowing the support member to be moved away from the main body in the removal direction.

[0072] (Item 5) The guide groove has a restricting surface that is parallel to the first direction, intersects the second direction, and faces the removal direction, The paper feeder according to claim 2, comprising: a fixed surface provided away from the restricting surface in the direction opposite to the removal direction, parallel to the first direction, intersecting the second direction, and facing in the direction opposite to the removal direction.

[0073] In this configuration, the guide groove has a restricting surface that is parallel to the first direction, intersects the second direction, and faces the removal direction. Therefore, the first projection can contact the restricting surface parallel to the first direction, and movement in the direction opposite to the removal direction is restricted when it is in contact with the restricting surface. The guide groove has a fixed surface that is parallel to the first direction, intersects the second direction, and faces the direction opposite to the removal direction. Therefore, the second projection can contact the fixed surface parallel to the first direction, and movement in the removal direction is restricted when it is in contact with the fixed surface. Thus, when the first projection is in contact with the restricting surface and the second projection is in contact with the fixed surface, movement of the support in the removal direction can be restricted.

[0074] (Item 6) The guide groove has a first guide surface facing the regulating surface, The paper feeding device according to claim 3, further comprising a second guiding surface facing the fixed surface.

[0075] In this configuration, the first guide surface faces the regulating surface, allowing the first projection to be brought into contact with the regulating surface and positioned on the support. Additionally, since the second guide surface faces the fixed surface, the second projection can be brought into contact with the fixed surface and positioned on the support.

[0076] (Item 7) The paper feed device according to Item 3, wherein the fixed surface is provided on the upstream side of the paper transport path of the two opposing sides that form the guide groove.

[0077] In this configuration, the fixed surface is located on the upstream side of the paper transport path, one of the two opposing sides that form the guide groove. Therefore, the rotational force that the separation roller receives from the sheet acts as a force directed toward the fixed surface on the second projection, allowing the second projection to be pressed against the fixed surface and preventing the position of the support part relative to the main body from shifting.

[0078] (Item 8) An operating part provided at the upper end of the support part, The device further comprises a protective wall located above the rotation axis of the separation roller in the normal operating position, and having an opening that leaves the upper portion of the separation roller open, The paper feeder according to item 2, wherein the removal direction is upward.

[0079] In this scenario, the protective wall is positioned above the separation roller in its normal operating position. Since the operating part is located at the upper end of the support and the removal direction is upward, after the separation roller moves in the removal direction, the operating part moves upward and is therefore positioned above the protective wall. As a result, the user can grasp the operating part, which is above the protective wall.

[0080] (Item 9) A support portion that pivotally supports the rotation axis of the separation roller, The system further comprises a main body that supports the aforementioned support portion, The paper feeding device according to item 1, wherein the extrusion portion is disposed between the support portion and the main body portion and includes an eject lever having a shape that increases in height as it moves away from the tip.

[0081] In this configuration, the rotation axis of the separation roller is supported by the support part, and an eject lever, which has a shape that increases in height as it moves away from the tip, is positioned between the support part and the main body. As a result, when the eject lever moves between the support part and the main body, the separation roller, whose rotation axis is supported by the support part, is pushed out in the removal direction. Thus, the separation roller can be pushed out in the removal direction with a simple configuration.

[0082] (Item 10) A paper feeder as described in any of Items 1 to 7, An image forming apparatus comprising an image forming unit that forms an image on a sheet conveyed by the aforementioned paper feed roller.

[0083] Following this approach, it is possible to provide an image forming apparatus that facilitates the replacement of the separation roller.

[0084] <Correspondence between embodiments and claims> The housing 11 is an example of the main body of the device. The paper feed roller 221 is an example of a paper feed roller. The separation roller 161 is an example of a separation roller. The separation shaft 165 is an example of the rotation axis of the separation roller. The separation holder 167 is an example of a support part. The torsion coil spring 177 is an example of an elastic member that biases the separation holder 167 toward the removal direction. The oscillating holder 171 is an example of the main body part. The Y direction is an example of the first direction. The part of the separation shaft 165 that protrudes from the separation holder 167 is an example of the first projection. The push-up projection 169 is an example of the second projection. The push-up projection 169 and the torsion coil spring 177 are an example of the push-up part. The up and down direction is an example of the second direction. The upward direction is an example of the removal direction. The guide groove 179 is an example of a guide groove.

[0085] The restricting surface 178A is an example of a restricting surface, and the fixed surface 179A is an example of a fixed surface. The first guide surface 178B is an example of a first guide surface, and the second guide surface 179B is an example of a second guide surface. The left direction, moving from the right to the left, is an example of the sheet transport direction. The operating unit 162 is an example of an operating unit. The side wall 153A of the paper feed tray 153 is an example of a protective wall. The eject lever 301 is an example of an eject lever. The MFP 100 is an example of an image forming apparatus.

[0086] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0087] 100 MFP, 11 Housing, 11A Side door, 13 Top end, 15 Paper output roller, 21C Image forming unit, 21K Image forming unit, 21M Image forming unit, 21Y Image forming unit, 23Y Transfer roller, 24 Drive roller, 24A Roller, 27 Intermediate transfer belt, 41 Main transport path, 140 Image forming section, 150 Paper feed device, 151, 152, 153, 154 Paper feed tray, 151a, 152a, 153a, 154a Sub-transport path, 153A Side wall, 155 Transport guide, 155A Opening, 157 Storage space, 158 Lifting plate, 159 Paper output tray, 160, 160A Separation unit, 161 Separation roller, 162 Operation section, 163 Limiter, 165 Separation shaft, 167 Separation holder, 167A second front side wall, 167B second rear side wall, 167C second connecting part, 169 push-up projection, 169A push-up projection, 171 oscillating holder, 171A first front side wall, 171B first rear side wall, 171C first connecting part, 173 oscillating shaft, 175 compression spring, 177 torsion coil spring, 177A spring shaft, 178A regulating surface, 178B first guide surface, 179 guide groove, 179A fixed surface, 179B second guide surface, 200 paper feed roller unit, 201 holding holder, 211 pick roller, 213 sorting shaft, 221 paper feed roller, 223 paper feed shaft, 301 eject lever.

Claims

1. A paper feed roller that transports the sheets, A separation roller that is detachable from the main body of the device and is located in the normal operating position facing the paper feed roller when mounted on the main body of the device, A paper feeding device comprising: an extrusion unit that pushes the separation roller, which is in the normal operating position, in the removal direction when the separation roller is removed from the main body of the device.

2. The system further includes a support portion that supports the rotation axis of the separation roller, The paper feeding device according to claim 1, wherein the extrusion portion includes an elastic member that biases the support portion toward the removal direction.

3. The main body portion that supports the aforementioned support portion, The separation roller further comprises a first projection and a second projection that protrude from the support portion in a first direction parallel to the rotation axis of the separation roller, The paper feeding device according to claim 2, wherein the main body has a shape that extends in a second direction parallel to the removal direction and has guide grooves that guide the first projection and the second projection.

4. The paper feeding device according to claim 3, wherein the elastic member is fixed to the main body and biases at least one of the first projection and the second projection in the removal direction.

5. The guide groove has a restricting surface that is parallel to the first direction, intersects the second direction, and faces the removal direction, The paper feeding device according to claim 3, further comprising: a fixed surface provided away from the restricting surface in the direction opposite to the removal direction, parallel to the first direction, intersecting the second direction, and facing in the direction opposite to the removal direction.

6. The guide groove has a first guide surface facing the regulating surface, The paper feeding device according to claim 5, further comprising a second guiding surface facing the aforementioned fixed surface.

7. The paper feeding device according to claim 5, wherein the fixed surface is provided on the upstream side of the paper transport path among the two opposing sides that form the guide groove.

8. An operating section provided at the upper end of the support section, The device further comprises a protective wall located above the rotation axis of the separation roller in the normal operating position, and having an opening that leaves the upper portion of the separation roller open, The paper feeding device according to claim 2, wherein the removal direction is upward.

9. A support portion that pivotally supports the rotation axis of the separation roller, The system further comprises a main body that supports the aforementioned support portion, The paper feeding device according to claim 1, wherein the extrusion portion includes an eject lever positioned between the support portion and the main body portion, and having a shape that increases in height as it moves away from the tip.

10. A paper feeder according to any one of claims 1 to 9, An image forming apparatus comprising an image forming unit that forms an image on a sheet conveyed by the aforementioned paper feed roller.

Images