JP6649629B2 - Paper feeder and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a sheet feeding device that feeds a sheet, and an image forming apparatus including the sheet feeding device.

  2. Description of the Related Art Conventionally, an image forming apparatus including a sheet feeding device for feeding a sheet is known. The sheet feeding device is configured to include a sheet feeding cassette detachably mounted on the apparatus main body of the image forming apparatus, and a pickup roller, a sheet feeding roller, and a retard roller disposed on the apparatus main body. In the paper feeding device, the sheet stored in the paper feeding cassette is taken out by a pickup roller, and sent out to a paper feeding nip formed by the paper feeding roller and the retard roller. The sheet that has reached the paper feed nip is conveyed toward the image forming unit by the rotation of the paper feed roller.

  Patent Literature 1 discloses a technique in which a retard roller is positioned at a contact position or a separation position with respect to a sheet feeding roller in conjunction with attachment and detachment of a sheet feeding cassette to and from the apparatus main body. In this technique, a pressing piece arranged in the apparatus main body is rotated in conjunction with the attachment / detachment of the paper feed cassette, and the rotating pressing piece is a holder pressed portion projected from a retard holder supporting a retard roller. Abut or separate from The retard holder is rotated by the abutting or separating operation of the pressing piece against the holder pressed portion. By the rotation of the retard holder, the retard roller can be positioned at the contact position or the separated position with respect to the sheet feeding roller.

JP-A-2005-093762

  In the technology disclosed in Patent Document 1, a mechanism for positioning a retard roller at a contact position or a separation position with respect to a paper feed roller is configured to include a pressing piece and a holder pressed portion, and a component of the component It has a large number of points and is a complicated mechanism involving a rotating operation. For this reason, there is a concern that a problem such as a mounting failure of the sheet cassette to the apparatus main body may occur. For example, a slight deviation of the contact angle of the paper feed cassette with the pressing piece may cause the pressing piece to rotate poorly. If the rotation of the pressing piece is defective, the mounting failure of the sheet cassette to the apparatus main body occurs, and therefore, the sheet feeding failure from the sheet cassette occurs.

  The present invention has been made in view of such circumstances, and an object of the present invention is to reduce a risk of occurrence of a defect such as a mounting failure of a sheet feeding cassette to an apparatus main body and to reduce a risk of sheets from the sheet feeding cassette. An object of the present invention is to provide a sheet feeding device having excellent sheet feeding characteristics and an image forming apparatus provided with the sheet feeding device.

A sheet feeding device according to one aspect of the present invention includes an apparatus main body, and a wall portion that is detachable along a predetermined horizontal mounting direction with respect to the apparatus main body, and that stands upright on a distal end side in the mounting direction. And a sheet feeding cassette including a sheet storage unit for storing sheets, and a sheet feeding device disposed in the apparatus main body and configured to convey the sheet stored in the sheet storage unit in a sheet conveyance direction along the mounting direction. A roller, a guide unit that guides the sheet conveyed by the paper feed roller, and is disposed opposite to the wall of the paper feed cassette in the apparatus main body; A retard roller capable of forming a sheet nip portion through which the sheet feeding cassette is pulled out from the apparatus main body. Disposed spaced apart position, to be movable in the vertical direction the retard roller across said separated position and the contact position in contact with the said feed roller, a retard roller unit supported by the guide unit, before Symbol comprising a first positioning mechanism you position the retard roller unit before Symbol abutting position and the previous SL spaced position. The first positioning mechanism is provided on the wall of the paper cassette and has a first engagement portion, which is a protrusion protruding from the wall in the mounting direction, and the first engagement portion is inserted therethrough. A second engagement portion, which is an insertion hole arbitrarily disposed in the retard roller unit, wherein the first engagement portion and the second engagement portion are interlocked with the attachment of the sheet cassette to the apparatus main body. By engaging the unit, the retard roller unit is moved upward from the separation position to be positioned at the contact position, and interlocked with the withdrawal of the sheet cassette from the apparatus main body. When the first engaging portion and the second engaging portion are separated from each other, the retard roller unit is moved downward from the contact position and positioned at the separated position.

  According to this paper feeder, the first positioning mechanism that positions the retard roller unit at the contact position or the separated position in conjunction with the attachment / detachment of the paper feed cassette with respect to the apparatus main body involves a rotating operation as in the related art. It is not a complicated mechanism but a simple mechanism for moving the retard roller unit in the vertical direction. For this reason, the risk of occurrence of problems such as improper attachment of the sheet cassette to the apparatus main body is reduced, and a highly reliable sheet feeding device having excellent sheet feeding characteristics of sheets from the sheet cassette is provided. Further, since the first positioning mechanism is constituted by a simple mechanism, the assemblability of the sheet feeding device is improved.

In addition, while the first engaging portion, which is a protrusion protruding in the mounting direction, is disposed on the wall of the sheet cassette, the second engaging portion is an insertion hole through which the first engaging portion can be inserted. The first positioning mechanism can be realized with a simple configuration in which the first positioning mechanism is disposed on the retard roller unit.

In the above-described paper feeding apparatus, in a state where the paper feeding cassette is pulled out from the apparatus main body, the retard roller unit is detachable from the guide unit, and the paper feeding cassette is mounted on the apparatus main body. in state, the first engagement portion, the distal portion from the second engagement portion is inserted into the second engaging portion so as to be exposed, the said guide unit, inserted into the second engagement portion It is good also as a structure in which the fitting recessed part which the said front-end | tip part of the said 1st engagement part fits was formed.

In this aspect, when the paper feed cassette is mounted on the apparatus main body, the first engagement portion, which is a protrusion disposed on the wall of the paper feed cassette , is a first through hole that is an insertion hole disposed on the retard roller unit . 2 is inserted through the engaging portion , and further fits into a fitting concave portion formed in a guide unit arranged in the apparatus main body. Accordingly, the positional relationship among the three members of the sheet cassette, the retard roller unit, and the guide unit is accurately maintained in a state where the sheet cassette is mounted on the apparatus main body. For this reason, the sheet accommodated in the sheet feed cassette passes through the sheet feed nip formed between the retard roller and the sheet feed roller, and the transportability when the sheet is guided and transported by the guide unit is stabilized. It will be.

  In the above-described sheet feeding device, the retard roller unit rotatably supports the retard roller, and a retard holder swingably supported by the retard roller unit, and the retard roller at the contact position includes the retard roller. And a biasing member for biasing the retard holder so as to press against the paper feed roller.

  In this aspect, the biasing member biases the retard holder with the retard roller unit positioned at the contact position by the first positioning mechanism. This makes it possible to increase the nip pressure in the paper feed nip formed between the retard roller and the paper feed roller.

  The above-mentioned sheet feeding device may further include a third engagement portion disposed on the wall portion of the sheet cassette outside the first engagement portion in a sheet width direction intersecting the sheet conveyance direction, and the guide unit. , A fourth engaging portion disposed outside the retard roller unit in the sheet width direction, wherein the third engaging portion and the fourth engaging portion engage with each other to form the sheet feeding cassette. It is good also as composition provided with the 2nd positioning mechanism which regulates the position to an apparatus main part further.

  In this aspect, since the position of the sheet cassette relative to the apparatus main body is regulated by the engagement of the third engagement portion and the fourth engagement portion constituting the second positioning mechanism, the sheet cassette, the retard roller unit, The positional relationship between the three guide unit units is maintained more accurately.

  In the paper feeder described above, the third engaging portion is a positioning pin projecting from the wall portion of the paper feed cassette in the mounting direction, and the fourth engaging portion is fitted with the positioning pin. It is good also as composition which is a positioning crevice arranged in the above-mentioned guide unit if possible.

  In this aspect, the third engagement portion and the fourth engagement portion that constitute the second positioning mechanism are each realized by a positioning pin and a positioning recess into which the positioning pin is fitted.

  An image forming apparatus according to another aspect of the present invention includes the sheet feeding device described above, and an image forming unit that forms an image on the sheet conveyed by the sheet feeding roller of the sheet feeding device.

  According to this image forming apparatus, since the above-described sheet feeding device having excellent sheet feeding characteristics from the sheet feeding cassette is provided, the image forming unit performs image forming processing due to sheet feeding failure. It is possible to suppress a decrease in efficiency.

  ADVANTAGE OF THE INVENTION According to this invention, the risk of generation | occurrence | production of malfunctions, such as mounting failure of a paper feed cassette with respect to an apparatus main body, was reduced, and the paper feeder excellent in the paper feed characteristic of the sheet from a paper feed cassette, and this paper feeder An image forming apparatus can be provided.

1 is a diagram schematically illustrating an internal structure of an image forming apparatus including a sheet feeding device according to an embodiment of the present disclosure. FIG. 3 is a perspective view of a sheet feeding cassette provided in the sheet feeding device. FIG. 3 is an enlarged perspective view showing a part of the sheet cassette of FIG. 2. FIG. 3 is an exploded perspective view showing, in an enlarged manner, the vicinity of a guide unit and a retard roller unit provided in the sheet feeding device. FIG. 3 is an enlarged perspective view showing the vicinity of a guide unit and a retard roller unit provided in the sheet feeding device. FIG. 6 is a cross-sectional view of the guide unit and the retard roller unit of FIG. 5 taken along the line VI-VI in a state where the sheet feeding cassette is pulled out from the main body housing. FIG. 7 is a cross-sectional view of the guide unit and the retard roller unit of FIG. 5 taken along the line VII-VII in a state where the sheet cassette is pulled out from the main body housing. FIG. 6 is a cross-sectional view of the guide unit and the retard roller unit of FIG. 5 taken along a line VIII-VIII in a state where the sheet feeding cassette is pulled out from a main body housing. FIG. 7 is a cross-sectional view corresponding to FIG. 6, in a state where the sheet feeding cassette is mounted on the main body housing. FIG. 8 is a cross-sectional view corresponding to FIG. 7 in a state where the sheet cassette is mounted on the main body housing.

  Hereinafter, a sheet feeding apparatus and an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. In the following, the directional relationship will be described using XYZ orthogonal coordinate axes. X direction corresponds to the left and right direction (+ X is right, -X is left), Y direction corresponds to the front and rear direction (+ Y is front, -Y is rear), and Z direction corresponds to the up and down direction (+ Z is up and -Z is down). I do. In the following description, the term “sheet” refers to copy paper, coated paper, OHP sheet, cardboard, postcard, tracing paper, other sheet materials to be subjected to image forming processing, or any processing other than image forming processing. Receiving sheet material.

[Overall Configuration of Image Forming Apparatus]
FIG. 1 is a diagram schematically showing an internal structure of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 is an electrophotographic apparatus that forms an image on a sheet S. Here, a monochrome printer is exemplified as the image forming apparatus 1. However, the image forming apparatus 1 may be a copying machine, a facsimile machine, or a multifunction machine having these functions, and a device that forms a color image. It may be.

  The image forming apparatus 1 includes a main body housing 10 having a substantially rectangular parallelepiped housing structure, a paper feeding device 20, an image forming unit 30, a fixing unit 40, and a toner container 50 housed in the main body housing 10. . Note that the main body housing 10 has a function as an apparatus main body that forms a part of the configuration of the sheet feeding device 20.

  The first cover 11 is disposed on the + Y side (front side) of the main body housing 10, and the second cover 12 is disposed on the −Y side (rear side). When the first cover 11 is opened, the toner container 50 is exposed outward from the main body housing 10. Thus, the user can take out the toner container 50 from the main housing 10 when the toner runs out. The second cover 12 is a cover that is opened at the time of sheet jam or maintenance. Each unit of the image forming unit 30 and the fixing unit 40 can be taken out of the main body housing 10 by opening the second cover 12. A paper discharge unit 13 is formed on the + Z side (upper side) of the main body housing 10. Further, the bottom portion 14 of the main body housing 10 is a portion of the main body housing 10 to which a paper feed cassette 21 described later, which forms a part of the configuration of the paper feed device 20, is detachably mounted.

  Further, a first sheet conveying path 15 and a second sheet conveying path 16 which are the conveying paths of the sheet S are formed in the main body housing 10. The first sheet transport path 15 is provided to face the paper discharge unit 13 on the + Z side (upper side) of the main body housing 10 from the paper supply device 20 via the image forming unit 30 and the fixing unit 40. It extends to the opening 13A and extends so as to pass through the image forming unit 30 from the −Z side (lower side) to the + Z side (upper side). The second sheet transport path 16 is a transport path for returning the single-side printed sheet S to the upstream side of the image forming unit 30 in the first sheet transport path 15 when performing double-sided printing on the sheet S. The second sheet conveying path 16 is formed between the outer surface of the reversing unit 16 </ b> A and the inner surface of the second cover 12 of the main housing 10. The second cover 12 and the reversing unit 16A are each rotatable around the axis of a main body fulcrum 16B provided at the lower end thereof. When a sheet jam occurs in the second sheet conveyance path 16, the second cover 12 is opened. When a sheet jam occurs in the first sheet conveying path 15 or when the image forming unit 30 is taken out, the reversing unit 16A is opened in addition to the second cover 12.

  The sheet feeding device 20 feeds the sheet S to the first sheet conveying path 15. The detailed configuration of the sheet feeding device 20 will be described later.

  The sheet S fed to the first sheet conveying path 15 by the sheet feeding device 20 is conveyed toward a pair of registration rollers 17 provided in the first sheet conveying path 15. The registration roller pair 17 has a function of correcting oblique conveyance of the sheet S. Thereby, the position of the image formed on the sheet S is adjusted. The registration roller pair 17 sends out the sheet S to the image forming unit 30 at the timing of the image forming process by the image forming unit 30.

  The image forming unit 30 performs an image forming process of forming a toner image on the sheet S sent by the registration roller pair 17. The image forming unit 30 includes a photosensitive drum 31 and a charging device 32, an exposure device (not shown), a developing device 33, a transfer roller 34, and a cleaning device 35 disposed around the photosensitive drum 31.

  The photoreceptor drum 31 is a cylindrical drum rotatable around a rotation axis extending in the X direction (left and right direction). The toner image is carried. The charging device 32 uniformly charges the surface of the photoconductor drum 31 and includes a charging roller that contacts the photoconductor drum 31.

  The cleaning device 35 has a cleaning blade (not shown), cleans the toner adhered to the peripheral surface of the photosensitive drum 31 after the transfer of the toner image, and conveys the toner to a collection device (not shown). The exposure apparatus has a laser light source and optical devices such as mirrors and lenses, and irradiates the outer peripheral surface of the photosensitive drum 31 with light modulated based on image data given from an external device such as a personal computer. Thus, an electrostatic latent image is formed. The developing device 33 supplies toner to the outer peripheral surface of the photosensitive drum 31 to develop the electrostatic latent image on the photosensitive drum 31 to form a toner image.

  The transfer roller 34 is a roller for transferring the toner image formed on the outer peripheral surface of the photosensitive drum 31 onto the sheet S. The transfer roller 34 is in contact with the outer peripheral surface of the photosensitive drum 31 to form a transfer nip. The transfer roller 34 is provided with a transfer bias having a polarity opposite to the polarity of the toner.

  The fixing unit 40 performs a fixing process for fixing the transferred toner image on the sheet S. The fixing unit 40 includes a fixing roller 41 having a heating source therein, and a pressure roller 42 pressed against the fixing roller 41 to form a fixing nip between the fixing roller 41 and the fixing roller 41. When the sheet S to which the toner image has been transferred is passed through the fixing nip, the toner image is fixed on the sheet S by heating by the fixing roller 41 and pressing by the pressing roller 42.

  The toner container 50 stores replenished toner to be supplied to the developing device 33. The replenishment toner stored in the toner container 50 is supplied into the developing device 33 from the toner outlet 52 by rotating the rotating member 51.

  After the image forming process is performed by the image forming unit 30 and then the fixing process is performed by the fixing unit 40, the sheet S is conveyed through the first sheet conveying path 15 toward the paper discharge port 13A. The paper is discharged onto the paper discharge unit 13 by a paper discharge roller pair 13B provided near the opening 13A.

  On the other hand, when the sheet S sent to the pair of discharge rollers 13B is for double-sided printing on which the image forming process for one side has been completed, the sheet S is held between the pair of discharge rollers 13B. Is done. The sheet S is switched back by the reverse rotation of the sheet discharge roller pair 13B in this state. As a result, the sheet S is sent to the second sheet conveying path 16. The sheet S sent to the second sheet conveying path 16 is reversely conveyed by a conveying roller provided in the second sheet conveying path 16, and again passed through a registration roller pair 17 in a state where the sheet S is turned upside down. 30. The sheet S supplied to the image forming unit 30 with the front and back reversed in this way is subjected to image forming processing on the back surface side, and then subjected to fixing processing by the fixing unit 40. The sheet S on which double-sided printing has been completed is conveyed through the first sheet conveying path 15, and is discharged onto the paper discharge unit 13 from the paper discharge port 13A by the paper discharge roller pair 13B.

[Detailed configuration of paper feeder]
Next, the configuration of the sheet feeding device 20 will be described in detail. The sheet feeding device 20 feeds the sheet S to the first sheet transport path 15. The paper supply device 20 includes a paper supply cassette 21, a pickup roller 22, a paper supply roller 23, a guide unit 24, and a retard roller unit 25.

  The sheet cassette 21 of the sheet feeding device 20 will be described with reference to FIGS. 2 and 3 in addition to FIG. FIG. 2 is a perspective view of a sheet cassette 21 provided in the sheet feeding device 20, and FIG. 3 is an enlarged perspective view showing a part of the sheet cassette 21 of FIG. The paper cassette 21 is detachable from the main housing 10 along a predetermined horizontal mounting direction DC. Here, the mounting direction DC is a direction from the + Y side (front side) to the −Y side (rear side). The sheet cassette 21 includes a sheet storage unit 211 and a lift plate 212. The sheet S is stored in the sheet storage unit 211. The sheet S accommodated in the sheet accommodating section 211 is conveyed through the first sheet conveying path 15 described above. In other words, the first sheet transport path 15 is a transport path that extends from the sheet storage unit 211 in the main body housing 10 and that transports the sheet S in the sheet transport direction DP along the mounting direction DC.

  The lift plate 212 is a plate-shaped body that is disposed on the bottom side of the sheet cassette 21 and lifts up a bundle of sheets S stored in the sheet storage unit 211 for feeding. The lift plate 212 moves the end of the sheet S stored in the sheet storage unit 211 on the downstream side in the sheet conveyance direction DP toward the pickup roller 22 by moving to the + Z side (upper side).

  The paper feed cassette 21 is formed in a box shape with an opening on the + Z side (upper side). In other words, the paper feed cassette 21 includes a cassette bottom wall portion 21A, a cassette front wall portion 21B standing upright on the + Z side (upper side) from front, rear, left and right edges of the cassette bottom wall portion 21A, and a cassette rear wall portion. 21C, a cassette left wall 21D, and a cassette right wall 21E.

  The cassette front wall 21 </ b> B defines the + Y side (front side) of the sheet cassette 21, and is arranged flush with the first cover 11 of the main body housing 10. The cassette rear wall 21 </ b> C defines the −Y side (rear side) of the sheet cassette 21. The cassette rear wall portion 21C is a wall portion that stands upright on the distal end side in the mounting direction DC in which the paper feed cassette 21 is mounted on the main body housing 10. The cassette left wall 21D is a side wall that is disposed along the mounting direction DC on the −X side (left side) of the paper feed cassette 21 so as to intersect with the cassette rear wall 21C. The cassette right wall portion 21E is a side wall disposed on the + X side (right side) of the sheet feeding cassette 21 in parallel with the cassette left wall portion 21D along the mounting direction DC.

  With reference to FIG. 1, the pickup roller 22 of the sheet feeding device 20 is disposed in the main body housing 10 so as to face an end of the sheet storage unit 211 on the downstream side in the sheet conveyance direction DP. The pickup roller 22 is rotated and driven to take out the sheets S one by one from the sheet storage unit 211 and send out the sheets S to the first sheet conveying path 11.

  The paper feed roller 23 is disposed downstream of the pickup roller 22 in the sheet transport direction DP in the main body housing 10. The paper feed roller 23 is disposed on the entrance side of the first sheet transport path 15 so as to face the sheet storage unit 211. The paper feed roller 23 is further driven to rotate, and further conveys the sheet S sent from the sheet storage unit 211 by the pickup roller 22 in the sheet conveyance direction DP.

  Next, the guide unit 24 and the retard roller unit 25 of the sheet feeding device 20 will be described with reference to FIGS. 4 to 10 in addition to FIG. FIG. 4 is an exploded perspective view illustrating the vicinity of the guide unit 24 and the retard roller unit 25 provided in the sheet feeding device 20 in an enlarged manner. FIG. 5 is an enlarged view illustrating the vicinity of the guide unit 24 and the retard roller unit 25. FIG. 6 to 8 are cross-sectional views of the guide unit 24 and the retard roller unit 25 in a state where the sheet cassette 21 is pulled out from the main housing 10, and FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 7 is a sectional view taken along line VII-VII of FIG. 5, and FIG. 8 is a sectional view taken along line VIII-VIII of FIG. 9 and 10 are cross-sectional views of the guide unit 24 and the retard roller unit 25 in a state where the sheet cassette 21 is mounted on the main body housing 10, and FIG. 9 is a cross-sectional view corresponding to FIG. Shows a sectional view corresponding to FIG.

  The guide unit 24 is a unit arranged inside the main body housing 10 so as to face the cassette rear wall 21 </ b> C of the paper feed cassette 21. The guide unit 24 guides the sheet S sent from the sheet storage unit 211 by the pickup roller 22 and further conveyed by the sheet feeding roller 23 from the −Z side (lower side). The guide unit 24 includes a first guide portion 241, a second guide portion 242, a guide unit bottom portion 243, a first mounting portion 244, and a second mounting portion 245.

  The first guide portion 241 is located on one side (−X side, left side) of the guide unit 24 in the sheet width direction (X direction, left / right direction) intersecting with the sheet conveyance direction DP, and on the + Z side (upper side). It is a part to do. The first guide portion 241 extends in the sheet width direction (X direction, left and right direction), and has a curved first guide surface 241A on an upper surface thereof. When the sheet cassette 21 is mounted on the main body housing 10, the first guide surface 241A is located on the + Z side (upper side) of the sheet cassette 21. The first guide surface 241A guides the sheet S conveyed by the paper feed roller 23 toward the registration roller pair 17.

  The second guide portion 242 is a portion of the guide unit 24 that is located on the other side (+ X side, right side) in the sheet width direction (X direction, left and right direction) and on the + Z side (upper side). The second guide portion 242 is spaced apart from the first guide portion 241 on the + X side (right side) in the sheet width direction (X direction, left and right direction). That is, a space is formed between the + X side (right side) end 241B of the first guide portion 241 and the −X side (left side) end 242B of the second guide portion 242. A later-described retard roller unit 25 is disposed in a space formed between the first guide portion 241 and the second guide portion 242. The second guide portion 242 extends in the sheet width direction (X direction, left and right direction), and has a curved second guide surface 242A on an upper surface thereof. When the sheet cassette 21 is mounted on the main housing 10, the second guide surface 242A is located on the + Z side (upper side) of the sheet cassette 21. The second guide surface 242A guides the sheet S conveyed by the paper feed roller 23 toward the registration roller pair 17 in cooperation with the first guide surface 241A of the first guide portion 241.

  The guide unit bottom 243 forms the bottom of the guide unit 24. The guide unit bottom portion 243 extends in the sheet width direction (X direction, left and right direction), and is disposed apart from the first guide portion 241 and the second guide portion 242 on the −Z side (lower side).

  The first mounting portion 244 has a facing wall portion 244A facing the cassette rear wall portion 21C of the paper feed cassette 21, and serves as a portion of the main body housing 10 where the paper feed cassette 21 is mounted. The first mounting part 244 is disposed between the first guide part 241 and the second guide part 242 and the guide unit bottom part 243. The first mounting portion 244 extends in the sheet width direction (X direction, left and right direction), and connects the first guide portion 241 and the second guide portion 242 to the guide unit bottom portion 243. Specifically, the first guide portion 241 and the second guide portion 242 are connected to the + Z side (upper side) end of the first mounting portion 244, and the -Z side (lower side) of the first mounting portion 244. Is connected to a guide unit bottom 243. Since the first guide portion 241 and the second guide portion 242 are spaced apart in the sheet width direction (X direction, left and right direction), the center at the + Z side (upper side) end of the first mounting portion 244 is set. A space in which a later-described retard roller unit 25 is disposed is formed above the portion.

  In the guide unit 24, the second mounting portion 245 is a structure to which a retard roller unit 25 described later is mounted and for supporting the retard roller unit 25. The second mounting portion 245 is disposed on the + X side (right side) end 241B of the first guide portion 241 and on the −X side (left side) end 242B of the second guide portion 242, respectively. Each of the second mounting portions 245 includes a slope portion 2451, a pair of protrusions 2452, and a hook-shaped protrusion 2453.

  The slope portion 2451 is a slope portion inclined from the + Y side (front side) toward the −Y side (rear side) toward the + Z side (upper side). A pair of protruding pieces 2452 is arranged at the -Y side (rear side) end of the slope portion 2451, in other words, at the + Z side (upper side) end of the slope portion 2451. The pair of projecting pieces 2452 project from the slope portion 2451 on the + Z side (upper side). A holder protruding piece 2522A formed on a retard holder 252 of the retard roller unit 25 described later is inserted into the locking groove 245A surrounded by the pair of protruding pieces 2452 and the slope portion 2451.

  Further, a hook-shaped protruding piece 2453 is arranged at the + Y side (front side) end of the slope portion 2451, in other words, at the −Z side (lower side) end of the slope portion 2451. The hook-shaped protruding piece 2453 protrudes from the slope portion 2451 on the + Y side (front side). A holder protruding pin 2522B formed on a retard holder 252 of the later-described retard roller unit 25 is inserted into the hook-shaped protruding piece 2453.

  The second mounting portion 245 is configured such that the holder protruding piece 2522A is inserted into a gap formed by the pair of protruding pieces 2452, and the holder protruding pin 2522B is inserted into the hook-shaped protruding piece 2453, whereby the retard roller unit 25 is inserted. I support.

  The retard roller unit 25 is a unit that includes a retard roller 251, a retard holder 252 that supports the retard roller 251, and an urging member 253. The retard roller unit 25 is detachable from the guide unit 24 in a state where the sheet cassette 21 is pulled out from the main housing 10. The retard roller unit 25 is located at a separation position where the retard roller 251 is separated from the paper feed roller 23 downward (−Z side) in a state where the paper cassette 21 is pulled out from the main body housing 10 (FIGS. 6 to 8). (A position shown in FIG. 3) is supported by the guide unit 24. Further, the retard roller unit 25 is movable in the Z direction (vertical direction) between the contact position (the position shown in FIGS. 9 and 10) where the retard roller 251 contacts the paper feed roller 23 and the separation position, It is supported by the guide unit 24. The retard roller unit 25 is supported by the second mounting portion 245 between the first guide portion 241 and the second guide portion 242 of the guide unit 24.

  In a state where the retard roller unit 25 is mounted on the second mounting portion 245 of the guide unit 24, the retard roller 251 is disposed below the paper feed roller 23 (−Z side) so as to face the paper feed roller 23. Is done. The retard roller 251 is a roller that can form a sheet nip N through which the sheet S passes between the sheet roller 23 and the sheet feed roller 23. When the retard roller unit 25 is moved upward from the separated position by the first positioning mechanism 26 described below and is positioned at the contact position, the retard roller 251 comes into contact with the sheet supply roller 23 and the sheet feeding nip. A part N is formed. The retard roller 251 is fixed to a rotating shaft via a torque limiter (not shown). Therefore, when a load of a predetermined torque or more is applied between the retard roller 251 and the rotating shaft, only the retard roller 251 rotates with the rotating shaft stopped. When one sheet S enters the sheet feeding nip N, the retard roller 251 rotates following the sheet feeding roller 23 and conveys the sheet S downstream in the sheet conveying direction DP. On the other hand, when a plurality of sheets S enter the sheet feeding nip portion N, the retard roller 251 stops, and only the uppermost sheet S is moved downstream by the sheet feeding roller 23 in the sheet conveying direction DP. Transported to The other sheets S stop at the sheet feeding nip N by abutting on the peripheral surface of the retard roller 251.

  In the retard roller unit 25, the retard holder 252 rotatably supports the retard roller 251 and is swingably supported with respect to the retard roller unit 25. The retard holder 252 is urged by an urging member 253 (see FIG. 8) in a state where the retard roller unit 25 is positioned at the contact position by a first positioning mechanism 26 described later. The urging member 253 is made of, for example, a coil spring, and urges the retard holder 252 so that the retard roller 251 is pressed against the paper feed roller 23. As a result, the nip pressure at the sheet feeding nip portion N formed between the retard roller 251 and the sheet feeding roller 23 can be increased. The retard holder 252 includes a holder bottom wall portion 2521, a pair of holder side wall portions 2522, a holder front wall portion 2523, and a holder rear portion that stand upright (upper side) from the front, rear, left, and right edges of the holder bottom wall portion 2521. It is configured to include a wall portion 2524 and an extension portion 2525.

  The pair of holder side walls 2522 define the + X side (right side) and the −X side (left side) of the retard holder 252, and are parallel side walls. A retard roller 251 is rotatably supported on the inner surfaces of the pair of holder side walls 2522. The retard roller 251 is supported by the pair of holder side walls 2522 so that a part thereof is exposed upward from the upper ends of the pair of holder side walls 2522. Further, on each outer surface of the pair of holder side wall portions 2522, a holder protruding piece 2522A is provided at an end on the -Y side (rear side), and a holder protruding pin 2522B is provided at an end on the + Y side (front side). ing.

  A holder projection 2522A and a holder projection pin 2522B provided on the + X side (right side) holder side wall portion 2522 project from the outer surface of the holder side wall portion 2522 to the + X side (right side), respectively. On the other hand, the holder protruding piece 2522A and the holder protruding pin 2522B provided on the −X side (left side) holder side wall portion 2522 protrude from the outer surface of the holder side wall portion 2522 on the −X side (left side), respectively.

  The holder protruding pieces 2522A provided on each of the pair of holder side wall portions 2522 are inserted into engagement grooves 245A formed by the pair of protruding pieces 2452 in the second mounting portion 245 of the guide unit 24. Further, the holder protruding pins 2522B provided on each of the pair of holder side wall portions 2522 are inserted into the hook-shaped protruding pieces 2453 of the second mounting portion 245 of the guide unit 24. Thus, the retard roller unit 25 is supported by the second mounting portion 245 of the guide unit 24.

  The holder front wall portion 2523 defines the + Y side (front side) of the retard holder 252. The holder front wall portion 2523 is disposed on the + Y side (front side) of the retard roller 251 supported by the pair of holder side wall portions 2522. A guide piece 2523A is provided at the upper end of the holder front wall 2523. The guide piece 2523A is a protrusion protruding from the upper end of the holder front wall 2523 in the sheet conveying direction DP. The guide piece 2523A guides the sheet S sent from the sheet storage unit 211 by the pickup roller 22 toward the sheet feeding nip N formed between the retard roller 251 and the sheet feeding roller 23.

  The holder rear wall portion 2524 defines the −Y side (rear side) of the retard holder 252. The holder rear wall portion 2524 is disposed on the −Y side (rear side) of the retard roller 251 supported by the pair of holder side wall portions 2522. The holder rear wall portion 2524 has a curved central guide surface 2524A. The central guide surface 2524A is disposed between the first guide surface 241A of the first guide portion 241 of the guide unit 24 and the second guide surface 242A of the second guide portion 242. The central guide surface 2524A guides the sheet S conveyed by the paper feed roller 23 toward the registration roller pair 17 in cooperation with the first guide surface 241A and the second guide surface 242A.

  In the retard holder 252, the extending portion 2525 is a plate-like body extending from the outer surface of the holder bottom wall portion 2521 to the −Z side (downward). In the retard roller unit 25, the extension 2525 of the retard holder 252 faces the cassette rear wall 21 </ b> C of the sheet cassette 21 mounted on the main body housing 10.

<About the first positioning mechanism>
Referring to FIGS. 3 to 5, 7, and 10, the sheet feeding device 20 according to the present embodiment includes a first positioning mechanism 26.

  As described above, in the state where the sheet cassette 21 is pulled out from the main body housing 10, the retard roller unit 25 is at the separated position where the retard roller 251 is separated from the sheet roller 23 downward (see FIGS. 6 to 8). Position) is supported by the guide unit 24.

  The first positioning mechanism 26 is in contact with the attachment / detachment of the paper feed cassette 21 to / from the main body housing 10, and a contact position where the retard roller 251 comes into contact with the paper feed roller 23 to form the paper feed nip N (FIGS. 10) and the separated position. Specifically, the first positioning mechanism 26 moves the retard roller unit 25 upward from the separated position in conjunction with the mounting of the paper feed cassette 21 in the mounting direction DC with respect to the main body housing 10. The retard roller unit 25 is positioned at the contact position. Further, the first positioning mechanism 26 moves the retard roller unit 25 downward from the contact position in conjunction with the pulling out of the sheet cassette 21 from the main body housing 10 to move the retard roller unit 25 away from the separation roller unit 25. Position in position.

  In the present embodiment, the first positioning mechanism 26 includes a pair of first engagement portions 261 disposed on the cassette rear wall 21 </ b> C of the sheet cassette 21 and a pair of second engagement portions disposed on the retard roller unit 25. Unit 262. The pair of first engaging portions 261 are arranged at a central portion in the sheet width direction (X direction, left and right direction) on the cassette rear wall portion 21C of the sheet cassette 21 so as to be separated from each other in the sheet width direction. As shown in FIG. 3, the pair of first engagement portions 261 are a pair of projections projecting from the cassette rear wall 21 </ b> C of the sheet cassette 21 in the mounting direction DC. On the other hand, as shown in FIG. 4 and FIG. 5, the pair of second engagement portions 262 are mutually in the sheet width direction (X direction, left and right direction) at the extension portion 2525 of the retard holder 252 configuring the retard roller unit 25. Are spaced apart from each other. The pair of second engagement portions 262 are a pair of insertion holes formed so that the pair of first engagement portions 261 can be inserted.

  In the first positioning mechanism 26 including the pair of first engagement portions 261 and the pair of second engagement portions 262, the first positioning mechanism 26 interlocks with the mounting of the sheet cassette 21 in the mounting direction DC in the main body housing 10. When the pair of first engagement portions 261 is inserted into the pair of second engagement portions 262, the retard roller unit 25 moves upward from the separated position to the contact position. The first positioning mechanism 26 positions the retard roller unit 25 at the contact position by inserting the pair of first engagement portions 261 through the pair of second engagement portions 262 and engaging with each other.

  On the other hand, in conjunction with pulling out of the paper feed cassette 21 from the main body housing 10 in the direction opposite to the mounting direction DC, the first positioning mechanism 26 includes a pair of first engagement portions 261 and a pair of second engagement members 261. By separating from the joining portion 262, the retard roller unit 25 is moved from the contact position to the separation position on the lower side by its own weight, and is positioned at the separation position.

  The first positioning mechanism 26 for positioning the retard roller unit 25 at the contact position or the separation position in conjunction with the attachment / detachment of the paper feed cassette 21 to / from the main body housing 10 has a complicated structure involving a rotating operation as in the related art. It is not a mechanism but a simple mechanism for moving the retard roller unit 25 in the vertical direction. For this reason, the risk of occurrence of a problem such as a mounting failure of the sheet cassette 21 with respect to the main body housing 10 is reduced, and the sheet feeding device 20 having excellent sheet feeding characteristics of the sheet S from the sheet cassette 21 and having high reliability is provided. . In addition, since the first positioning mechanism 26 is constituted by a simple mechanism, the assemblability of the sheet feeding device 20 is improved.

  When the sheet cassette 21 is mounted on the main body housing 10, the first positioning mechanism 26 moves the retard roller 251 to the contact position where the retard roller 251 contacts the sheet roller 23 to form the sheet nip N. The roller unit 25 is positioned. When the sheet cassette 21 is pulled out of the main body housing 10 in a state where the sheet S is sandwiched by the sheet nip portion N, the sheet S sandwiched by the sheet nip portion N remains inside the main body housing 10. There is a possibility that it will.

  Therefore, the first positioning mechanism 26 moves the retard roller unit 25 from the contact position to the separated position on the lower side in conjunction with the drawing of the sheet cassette 21 from the main body housing 10. Therefore, when the sheet cassette 21 can be pulled out of the main housing 10, the retard roller 251 can be separated from the sheet roller 23. As a result, when the sheet cassette 21 is pulled out from the main housing 10, the pressing force on the sheet S at the sheet nip N is released. Therefore, the sheet cassette 21 is pulled out while the sheet S sandwiched between the sheet nip portions N and the other sheets S stored in the sheet cassette 21 are in contact with each other due to a static friction force. Therefore, the sheet S sandwiched between the sheet feeding nip portions N can be taken out of the main body housing 10 together with the sheet feeding cassette 21, and the sheet S is prevented from remaining in the main body housing 10.

  In addition, as shown in FIGS. 4, 7, and 10, in the sheet feeding device 20 according to the present embodiment, the guide unit 24 is formed with a pair of fitting recesses 263. The pair of fitting recesses 263 are formed in the opposite wall portion 244A of the first mounting portion 244 of the guide unit 24 at a central portion in the sheet width direction (X direction, left and right direction), and are separated from each other in the sheet width direction. . In a state where the retard roller unit 25 is mounted on the second mounting portion 245 of the guide unit 24, the pair of fitting concave portions 263 are formed by the extending portions of the retard roller unit 25 where the pair of second engaging portions 262 are arranged. It is covered from the + Y side (front side) by 2525.

  In a state where the sheet cassette 21 is mounted on the main body housing 10, the pair of first engagement portions 261 have their distal ends exposed from the pair of second engagement portions 262 to the −Y side (rear side). Is inserted through. The distal ends of the pair of first engaging portions 261 inserted into the pair of second engaging portions 262 can be fitted into the pair of fitting concave portions 263.

  When the sheet cassette 21 is mounted on the main body housing 10, the pair of first engagement portions 261 arranged on the cassette rear wall 21 </ b> C of the sheet cassette 21 are paired with the pair of first engagement portions 261 arranged on the retard roller unit 25. It is inserted through the two engaging portions 262 and further fits into a pair of fitting concave portions 263 formed in the guide unit 24 arranged in the main body housing 10. Thus, the positional relationship among the three members of the sheet cassette 21, the retard roller unit 25, and the guide unit 24 is accurately maintained in a state where the sheet cassette 21 is mounted on the main body housing 10. For this reason, the sheet S stored in the sheet storage unit 211 of the paper feed cassette 21 passes through the paper feed nip N formed between the retard roller 251 and the paper feed roller 23, and is guided by the guide unit 24. And the transportability when transported is stabilized.

  When the paper cassette 21 is mounted on the main housing 10, the paper cassette 21 may be mounted on the main housing 10 while an excessive force is applied in the mounting direction DC. In this case, there is a possibility that the paper feed cassette 21 is mounted on the main housing 10 in a state where the retard roller unit 25 is displaced from the guide unit 24. As a countermeasure for preventing such a displacement of the retard roller unit 25 with respect to the guide unit 24, a fixing member for fixing the retard roller unit 25 to the guide unit 24 may be provided. However, when the retard roller unit 25 is configured to be fixed by the fixing member, for example, when the operation of replacing the retard roller 251 is performed, the number of work steps related to the replacement operation increases. This is because when the retard roller unit 25 is removed from the guide unit 24, it is necessary to first remove the fixing member, and after the retard roller unit 25 is attached to the guide unit 24, it is necessary to fix the retard roller unit 25 with the fixing member. This is because the number of work steps increases.

  On the other hand, in the present embodiment, the holder protruding pieces 2522A provided on each of the pair of holder side wall portions 2522 are formed by the locking grooves 245A formed by the pair of protruding pieces 2452 in the second mounting portion 245 of the guide unit 24. , Whereby the retard roller unit 25 is supported by the second mounting portion 245 of the guide unit 24. For this reason, in the state where the retard roller unit 25 is supported by the guide unit 24, the rearward movement of the retard roller unit 25 is prevented, so that a fixing member for preventing displacement is not required. As a result, it is possible to suppress an increase in the number of work steps related to the replacement work of the retard roller 251 and to improve the work efficiency of the replacement work.

<About the second positioning mechanism>
3 to 5, the sheet feeding device 20 according to the present embodiment includes a second positioning mechanism 27. The second positioning mechanism 27 regulates the position of the paper feed cassette 21 with respect to the main body housing 10 when the paper feed cassette 21 is mounted on the main body housing 10.

  The second positioning mechanism 27 includes a pair of third engaging portions 271 arranged on the cassette rear wall 21 </ b> C of the sheet cassette 21 and a pair of fourth engaging portions 272 arranged on the guide unit 24. As illustrated in FIG. 3, the pair of third engagement portions 271 are located outside the pair of first engagement portions 261 in the sheet width direction (X direction, left and right direction) on the cassette rear wall portion 21 </ b> C of the sheet cassette 21. Are located in The pair of third engagement portions 271 are a pair of positioning pins that protrude from the cassette rear wall 21 </ b> C of the sheet cassette 21 in the mounting direction DC. On the other hand, as shown in FIGS. 4 and 5, the pair of fourth engagement portions 272 are mounted on the second mounting portion 245 of the guide unit 24 at the opposite wall portion 244A of the first mounting portion 244 of the guide unit 24. Of the retard roller unit 25 in the sheet width direction (X direction, left and right direction). The pair of fourth engaging portions 272 are a pair of positioning concave portions formed so that the pair of third engaging portions 271 formed of a pair of positioning pins can be fitted.

  In the second positioning mechanism 27 composed of a pair of third engagement portions 271 formed of a pair of positioning pins and a pair of fourth engagement portions 272 formed of a pair of positioning recesses, the main body housing 10 of the sheet cassette 21 is provided. The pair of third engagement portions 271 is fitted to the pair of fourth engagement portions 272 in conjunction with the mounting along the mounting direction DC. The second positioning mechanism 27 regulates the position of the sheet cassette 21 with respect to the main body housing 10 by the pair of third engagement portions 271 being fitted to the pair of fourth engagement portions 272 and engaging with each other.

  On the other hand, in conjunction with pulling out of the paper feed cassette 21 from the main body housing 10 in a direction opposite to the mounting direction DC, the second positioning mechanism 27 includes a pair of third engagement portions 271 and a pair of fourth engagement members 271. By moving away from the joint 272, the restriction on the position of the sheet cassette 21 with respect to the main body housing 10 is released.

  In the sheet feeding device 20 including the second positioning mechanism 27, the engagement of the pair of third engaging portions 271 and the pair of fourth engaging portions 272 constituting the second positioning mechanism 27 causes Since the position with respect to the main body housing 10 is regulated, the positional relationship among the three members of the sheet feed cassette 21, the retard roller unit 25, and the guide unit 24 is more accurately maintained.

  Further, when the cassette rear wall portion 21C of the paper feed cassette 21 is mounted on the main body housing 10 in a state of being inclined on a horizontal plane with respect to the mounting direction DC, the sheet S is likely to be skewed. On the other hand, the pair of fourth engagement portions 272 constituting the second positioning mechanism 27 are arranged outside the retard roller unit 25 in the guide unit 24 in the sheet width direction (X direction, left and right direction). . For this reason, the engagement position between the pair of third engagement portions 271 and the pair of fourth engagement portions 272 for regulating the position of the sheet cassette 21 with respect to the main body housing 10 is set so as to sandwich the retard roller unit 25. Formed. This prevents the cassette rear wall portion 21C of the sheet cassette 21 from being mounted on the main body housing 10 in a state where the rear wall portion 21C is inclined with respect to the mounting direction DC, thereby suppressing the oblique conveyance of the sheet S.

  Further, since the image forming apparatus 1 of the present embodiment includes the sheet feeding device 20 having excellent sheet feeding characteristics of the sheet S from the sheet feeding cassette 21, the image forming unit 1 30 can be prevented from lowering the efficiency of the image forming process.

  As described above, the embodiments of the present invention have been described, but the present invention is not limited to the embodiments, and various modified embodiments can be adopted.

  (1) In the above embodiment, the pair of first engaging portions 261 and the pair of second engaging portions 262 constituting the first positioning mechanism 26 of the sheet feeding device 20 are formed by the pair of first engaging portions 261. A pair of projections projecting from the cassette rear wall 21C of the sheet cassette 21 in the mounting direction DC, and a pair of second engagement portions 262 are a pair of insertion holes arranged in the retard roller unit 25. However, the present invention is not limited to such a configuration. For example, the pair of first engaging portions 261 are a pair of concave portions arranged on the cassette rear wall portion 21C of the paper feed cassette 21, and the pair of second engaging portions 262 can be inserted into the pair of concave portions. The configuration may be a pair of protrusions arranged in the unit 25.

  (2) In the above-described embodiment, the pair of third engagement portions 271 and the pair of fourth engagement portions 272 constituting the second positioning mechanism 27 of the sheet feeding device 20 correspond to the pair of third engagement portions. A pair of positioning pins 271 project from the cassette rear wall 21C of the sheet cassette 21 in the mounting direction DC, and a pair of fourth engagement portions 272 are a pair of positioning recesses arranged in the guide unit 24. Although the configuration has been described, the present invention is not limited to such a configuration. For example, the pair of third engaging portions 271 is a pair of positioning concave portions arranged on the cassette rear wall portion 21C of the sheet cassette 21, and the pair of fourth engaging portions 272 can be fitted with the pair of positioning concave portions. It may be configured to be a pair of positioning pins arranged on the guide unit 24.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Main body housing (apparatus main body)
REFERENCE SIGNS LIST 20 sheet feeding device 21 sheet feeding cassette 211 sheet storage section 22 pickup roller 23 sheet feeding roller 24 guide unit 25 retard roller unit 251 retard roller 252 retard holder 26 first positioning mechanism 261 first engagement section 262 second engagement section 263 Fitting recess 27 Second positioning mechanism 271 Third engaging part 272 Fourth engaging part 30 Image forming part 40 Fixing part 50 Toner container

Claims (6)

The device body,
A sheet cassette, which is detachable along a predetermined horizontal mounting direction with respect to the apparatus main body, and includes a wall portion erected on the distal end side in the mounting direction, and a sheet accommodating portion for accommodating sheets. ,
A paper feed roller disposed on the apparatus main body and transporting the sheet accommodated in the sheet accommodating portion in a sheet transport direction along the mounting direction,
A guide unit configured to guide the sheet conveyed by the sheet feeding roller, the guide unit being disposed to face the wall of the sheet feeding cassette in the apparatus main body;
A retard roller that can form a paper nip portion through which the sheet passes between the paper feed roller and the retard roller that extends downward from the paper feed roller when the paper feed cassette is pulled out of the apparatus main body. A retard roller unit supported by the guide unit, which is disposed at a separated position separated to the side, and is movable in the vertical direction between the contact position where the retard roller is in contact with the paper feed roller and the separated position.
Before SL and a first positioning mechanism you positioned before SL in the abutting position and the previous SL separated position the retard roller unit,
The first positioning mechanism includes:
A first engagement portion that is a projection that is disposed on the wall portion of the paper feed cassette and protrudes from the wall portion in the mounting direction; and the first roller that allows the first engagement portion to be inserted into the retard roller unit. A second engaging portion, which is an inserted through hole,
The first engagement portion and the second engagement portion are engaged with each other in conjunction with the attachment of the sheet cassette to the apparatus main body, so that the retard roller unit is moved upward from the separated position. To position at the contact position,
The retard roller unit is moved downward from the contact position by separating the first engagement portion and the second engagement portion in conjunction with pulling out the sheet cassette from the apparatus main body. A sheet feeding device for positioning the sheet at the separated position . In a state where the sheet cassette is pulled out from the apparatus main body, the retard roller unit is detachable from the guide unit,
In a state where the sheet cassette is attached to the apparatus main body, the first engagement portion, the tip portion is inserted into the second engaging portion so as to be exposed from the second engaging portion,
2. The sheet feeding device according to claim 1 , wherein the guide unit is formed with a fitting recess in which the distal end of the first engaging portion inserted through the second engaging portion can be fitted. 3. The retard roller unit includes:
A retard holder that rotatably supports the retard roller and that is swingably supported by the retard roller unit,
Wherein at the contact position, including a biasing member to which the retard roller biases the retard holder so as to press the sheet feed roller, the paper feeding apparatus according to claim 1 or 2. A third engaging portion disposed outside the first engaging portion in a sheet width direction intersecting with the sheet conveying direction on the wall portion of the sheet feeding cassette; A fourth engaging portion disposed on the outside in the sheet width direction, wherein a position of the sheet cassette relative to the apparatus main body is regulated by engagement of the third engaging portion and the fourth engaging portion. The sheet feeding device according to any one of claims 1 to 3 , further comprising a second positioning mechanism. The third engagement portion is a positioning pin projecting from the wall portion of the sheet cassette in the mounting direction.
The paper feeding device according to claim 4 , wherein the fourth engagement portion is a positioning recess arranged in the guide unit so that the positioning pin can be fitted therein. A sheet feeding device according to any one of claims 1 to 5 ,
An image forming unit configured to form an image on the sheet conveyed by the sheet feeding roller of the sheet feeding device.

Images