Patent Application
20220082980
The present invention relates to a sheet feeding device for feeding a sheet and an image forming apparatus for forming an image on the sheet.
In the image forming apparatus such as a copying machine, a printer or a facsimile machine, a constitution in which a sheet accommodating portion (also called a feeding cassette, a feeding tray, or the like) for accommodating sheets is detachably mounted in an apparatus main assembly and in which the sheets in the sheet accommodating portion are fed one by one automatically has been widely used. In Japanese Laid-Open Patent Application (JP-A) Hei 8-119464, a constitution in which an engaging member formed of an elastic plastic material is provided in an apparatus main assembly of an image forming apparatus and in which a member-to-be-engaged engaged with the engaging member is provided in a sheet feeding tray is described. When the sheet feeding tray is inserted into the apparatus main assembly, the member-to-be-engaged is nipped between two finger portions of the engaging member, so that the sheet feeding tray is brought into a mounting position and thus is positioned with respect to a mounting and dismounting direction relative to the apparatus main assembly.
A principal object of the present invention is to provide a sheet feeding device and an image forming apparatus which has further developed a conventional constitution.
According to an aspect of the present invention, there is provided a sheet feeding device comprising: a sheet accommodating portion mounted in a main assembly so as to be capable of being pulled out in a pulling-out direction from a mounting position in the main assembly; wherein with respect to a crossing direction perpendicularly crossing the pulling-out direction of the sheet accommodating portion from the main assembly as viewed in a direction of gravitation, the main assembly is provided with a positioning portion for positioning the sheet accommodating portion mounted at the mounting position, a member-to-be-engaged provided in one of the main assembly and the sheet accommodating portion; and an engaging member, provided in the other of the main assembly and the sheet accommodating portion, which is formed of an elastic material and which is configured to hold the sheet accommodating portion at the mounting position by being engaged with the member-to-be-engaged, wherein the engaging member is elastically deformed when the sheet accommodating portion is pulled out in the pulling-out direction from the mounting position, and wherein the engaging member is provided swingably in the other one of the main assembly and the sheet accommodating portion so as to be capable of changing a position thereof with respect to the crossing direction.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Parts (a) to (d) of
Parts (a) and (b) of
Parts (a) to (c) of
Parts (a) and (b) of
In the following, embodiments of the present invention will be described with reference to the drawings.
The printer 201 includes a printer main body 201A accommodating an image forming portion 201B and an image reading device 202 disposed on the printer main body 201A and for reading the image information from the original. With respect to an up-down direction (direction of gravitation), between the image reading device 202 and the printer main body 201A, a discharge space S into which the sheet P on which the image is formed is discharged is formed.
The image forming portion 201B which is an example of an image forming means is an electrophotographic unit of an intermediary transfer type including four process cartridges 211 and an intermediary transfer unit 201C. Each of the process cartridges 211 forms a toner image on a surface of a photosensitive drum 212 by an electrophotographic process. That is, when preparation of the toner image is required to the image forming portion 201B, the photosensitive drum 212 which is an image bearing member (electrophotographic photosensitive member) is rotationally driven, and the surface of the photosensitive drum 212 is electrically charged uniformly by a charging device 213. An exposure device 210 provided at a lower portion of the printer main body 201A irradiates the surface of the photosensitive drum 212 with laser light based on the image information, so that an electrostatic latent image is formed (written) on the photosensitive drum 212. A developing device 214 develops the electrostatic latent image on the surface of the photosensitive drum 212 into a toner image by using a developer including charged toner particles. Respective color toner images formed in the four process cartridges 211 are primary-transferred from the photosensitive drums 212 onto an intermediary transfer belt 216 by primary transfer rollers 219. A deposited matter such as toner remaining on the photosensitive drum 212 is removed by a cleaning device provided in each of the process cartridges 211.
The intermediary transfer unit 201C includes the intermediary transfer belt 216 which is an intermediary transfer member, and the intermediary transfer belt 216 is wound around an inner secondary transfer roller 216a, a tension roller 216b, and the like and is rotationally driven in the counterclockwise direction in the figure. The toner images carried on the intermediary transfer belt 216 are secondary-transferred onto the sheet P in a secondary transfer portion formed between the intermediary transfer belt 216 and a secondary transfer roller 217 opposing the inner secondary transfer roller 216a though the intermediary transfer belt 216. A deposited matter such as the toner remaining on the intermediary transfer belt 216 is removed by a cleaning device.
The sheet P on which the toner images are transferred is delivered to a fixing device 220. The fixing device 220 which is a fixing means in this embodiment includes a fixing roller 161 as a heating member, a pressing roller 162 for nipping the sheet in cooperation with the fixing roller 161, and a heat-generating member 163 (for example, a halogen lamp) as a heating means for heating the toner image on the sheet P. The fixing device 160 melts the toner by imparting heat and pressure to the toner image while feeding the sheet P, and thereafter the toner is fixed, so that the image is fixed on the sheet P.
In parallel to such an image forming process, the sheets P are fed one by one from a cassette feeding portion 230 or a multi-feeding portion 300 toward a registration roller pair 240. The cassette feeding portion 230 includes a feeding cassette 1 in which the sheets P are stacked and a feeding unit for feeding the sheet P from the feeding cassette 1. The feeding unit includes a pick-up roller 8 for sending the sheet P from the feeding cassette 1 and a feed roller 9 (feeding roller) for feeding the sheet P received from the pick-up roller 8. Further, a retard roller 7 which forms a nip in contact with the feed roller 9 and which separates the sheets P, one by one, fed by the feed roller 9 by applying a frictional force to the sheet P in the nip is provided.
To the retard roller 7, a driving force in a direction against rotation of the feed roller 9 is inputted via a torque limiter. When a single sheet P passes through the nip, the torque limiters slips, so that the retard roller 7 is rotated by the feed roller 9. On the other hand, when a plurality of sheets P enter the nip, the retard roller 7 rotates in the direction against the rotation of the feed roller and pushes back the sheet P to the feeding cassette 1. Such a retard roller 7 is an example of a separating member for separating the sheet P, and as the retard roller 7, a roller member connected to a fixed shaft via the torque limiter may be used and a pad-like elastic member may also be used.
The multi-feeding portion 300 includes a multi-tray 13 as a sheet supporting means and a feeding unit for feeding the sheet P set on the multi-tray 13. A structure of the feeding unit of a multi-feeding portion 300 is basically similar to the structure of the feeding unit of the cassette feeding portion 230. The multi-tray 13 is also called a multi-purpose tray or a manual feeding tray.
The sheet P fed from the cassette feeding tray 230 or the multi-feeding portion 300 is fed to the registration roller pair 240 via a sheet feeding passage in the printer main body 201A and then is subjected to oblique movement correction by the registration roller pair 240 put in a rest state. The sheet P subjected to the oblique movement correction is fed to the secondary transfer portion by the registration roller pair 240 at a timing in synchronism with the image forming process by the image forming portion 201B.
The sheet P on which the image is formed through passing of the secondary transfer portion and the fixing device 220 is discharged in the discharge space S by a first discharging roller pair 225a or a second discharging roller pair 225b and is stacked on a stacking portion 223. Incidentally, in the case of double-side printing, the sheet P on which the image is formed on a first surface thereof is reversely fed by a reversing roller pair 222 (switch-back feeding) and is delivered to a double-side feeding portion 201D, and then is fed again to the registration roller pair 240 via a re-feeding passage R. Thereafter, the sheet P on which an image is formed on a second surface thereof by being passed through the secondary transfer portion and the fixing device 230 is discharged in the discharge space S by the first discharging roller pair 225a or the second discharging roller pair 225b, so that the sheet P is stacked on the stacking portion 223.
The above-described image forming operation is controlled by a controller mounted in the printer main body 201A. Further, in the above description, the image forming portion 201B is an example of the image forming means, and as the image forming portion 201B, an electrophotographic unit of a direct transfer type or an image forming unit of an ink jet type or an offset printing type may also be used.
The cassette feeding portion 230 which is a sheet feeding device of this embodiment will be further described.
The sheet P stacked in the feeding cassette 1 is fed from the feeding cassette 1 toward a feeding direction X1 by the feed roller 9 or the like described using
The feeding cassette 1 includes a substantially box-shaped (tray-like) cassette frame 2 opening or an upper side thereof, a stacking plate 21, side restricting portions 20F and 20R, and a trailing end restricting portion 11. The stacking plate 21 is rotatably supported by the cassette frame 2 and is capable of being raised and lowered in a state in which sheets are stacked at an upper surface thereof. The side restricting portions 20F and 20R is provided on one side and the other side with respect to a sheet widthwise direction (i.e., the mounting and dismounting direction Y) perpendicular to the feeding direction X1, and is mounted movably in the sheet widthwise direction along a rail 2b provided at a bottom 2a of the cassette frame 2. The trailing end restricting portion 11 is mounted movably in the feeding direction X1 along a rail 2c provided at the bottom 2a of the cassette frame 2. The side restricting portions 20F and 20R, and the trailing end restricting portion 11 contact end portions of the sheets stacked on the stacking plate 21 and thus restrict positions of the sheets set in the feeding cassette 1. Further, depending on a sheet size, positions of the side restricting portions 20F and 20R, and the trailing end restricting portion 11 are changed, so that sheets with various sizes can be accommodated in the feeding cassette 1.
Next, a constitution for holding and positioning the feeding cassette 1 in a mounting state will be described using parts (a) to (d) of
As shown in the left side of part (a) of
Further, at the rear portion of the feeding cassette 1, a positioning shaft 31 as a first portion-to-be-positioned is provided. The printer main body 201A is provided with a bearing portion 32 as a first positioning portion on the rear side of the cassette mounting space. The positioning shaft 31 and the bearing portion 32 constitute a rear-side positioning mechanism 30 (first positioning mechanism) for positioning the feeding cassette 1 with respect to the left-right direction X.
As shown in the right side of part (a) of
These engaging portion 40, rear-side positioning mechanism 30 and front-side positioning mechanism 33 have a function of restricting movement of the feeding cassette 1 mounted at a predetermined mounting position in the printer main body 201A and of holding the feeding cassette 1 in the mounting position. In the following, members constituting the engaging portion 40, the rear-side positioning mechanism 30, and the front-side positioning mechanism 33 will be specifically described.
The engaging arm 42 made of a resin material projects from the cassette frame 2 toward the downstream side of the mounting direction Y2 and is supported by the cassette frame 2 so as to be swingable about a swing axis 43. The swing axis may preferably be an axis extending in the up-down direction (direction of gravitation). The boss member 41 is substantially cylindrical member extending in the up-down direction which is a direction substantially parallel to the swing axis 43 of the engaging arm 42, and is fixed to a frame of the printer main body 201A.
The engaging arm 42 includes two claw portions (arm portions) 42a and guiding portions 42b provided at free ends of the claw portions 42a. By the two claw portions 42a, a locking portion 42d which is recessed portion for receiving the boss member 41 is formed (see also part (a) of
The locking portion 42d has a recessed shape such that as viewed from above, the locking portion 42d is open toward the downstream side of the mounting direction Y2 via an opening between two narrow portions 42c each positioned at a boundary between the claw portion 42a and the guiding portion 42b. A distance between the two narrow portions 42c which is an opening width of the engaging arm 42 is set so as to be smaller than a width of the boss member 41 with respect to the left-right direction X. The two guiding portions 42a are formed so that an interval therebetween with respect to the left-right direction increases from the narrow portions 43c toward the downstream side of the mounting direction Y2 becomes larger than a maximum width of the boss member 41.
In the case where the two guiding portions 42a are pressed by the boss member 41, the two claw portions 42a have elasticity such that the two claw portions 42a are capable of elastically deforming so that the distance between the narrow portions 42c increases to a width in which the boss member 41 is capable of passing.
As shown in the left side of part (a) of
The bearing portion 32 is portion fixed to the frame of the printer main body 201A and forming a hole extending in the mounting direction Y2 at a position opposing the positioning shaft 31. An inner diameter of the bearing portion 32 is set so as to be substantially equal to the outer diameter of the cylindrical portion 31b of the positioning shaft 31.
As shown in the right side of part (a) of
The bearing portion 35 is portion fixed to the frame of the printer main body 201A and forming a hole extending in the mounting direction Y2 at a position opposing the positioning shaft 34. An inner diameter of the bearing portion 35 is set so as to be substantially equal to the outer diameter of the cylindrical portion 34b of the positioning shaft 34.
A difference between each of the inner diameters of the bearing portions 32 and 35 and each of the outer diameters of the cylindrical portions 31b and 31d of the positioning shafts 31 and 34 determines positional accuracy of the feeding cassette 1 with respect to the left-right direction X in the mounted state. The difference between each of the inner diameters of the bearing portions 32 and 35 and each of the outer diameters of the cylindrical portions 31b and 34b is smaller than play with respect to the left-right direction X at the engaging portion between the rail of the printer main body 201A and the guiding portion 2g (
Operations of the engaging portion 40, the rear-side positioning mechanism 30, and the front-side positioning mechanism 33 when the feeding cassette 1 is mounted will be described along parts (a) to (d) of
Part (a) of
As shown in part (b) of
As shown in part (c) of
As shown in part (d) of
Further, in the rear-side positioning mechanism 30 and the front-side positioning mechanism 33, the cylindrical portions 31b and 34b of the positioning shafts 31 and 34 engage with the bearing portions 32 and 35, respectively. By this, the feeding cassette 1 is positioned with respect to the left-right direction X crossing the mounting and dismounting direction Y. Further, both the rear side and the front side of the mounting direction Y2, so that turn (rotation as viewed from above) of the feeding cassette 1 is also restricted.
Incidentally, the start of the engagement of the cylindrical portions 31b and 34b of the positioning shafts 31 and 34 with the bearing portions 32 and 35, respectively, is set at a timing after the largest width portion of the boss member 41 passes through between the narrow portions 42c of the engaging arm 42 and before the boss member 41 reaches the locking portion 42d. By this, the feeding cassette 1 can be maintained at the mounting position in a state in which positional accuracy of the feeding cassette 1 with respect to the left-right direction X is ensured.
By using parts (a) and (b) of
In part (a) of
The swing range of the engaging arm 42 is set so that guiding of the boss member 41 by the guiding portions 42b is enabled even when the engaging arm 42 is positioned with any angle within the swing range. That is, even in either state of parts (a) and (b) of
Further, the swing range of the engaging arm 42 is set in consideration of a variation in positional relationship between members due to a part tolerance, an assembling tolerance, and the like. By using parts (a) to (c) of
As shown in part (a) of
As shown in part (b) of
If the engaging arm 42 is a member fixed to the cassette frame 2, it is assumed that the engaging arm 42 and the positioning shaft 31 are engaged with the boss member 41 and the bearing portion 32, respectively, in the state shown in part (b) or part (c) of
On the other hand, in this embodiment, the variation in positional relationship between the members due to the part tolerance, the assembling tolerance, and the like is absorbed by the engaging arm 42 swingably in the direction crossing the mounting and dismounting direction Y, and therefore, the possibility that the deformation and the breaking of the members occur is decreased. Accordingly, a lowering in functions of the pulling-in and the positioning by the engaging portion 40 and the rear-side positioning mechanism 30 is suppressed, and the feeding cassette 1 is capable of being smoothly mounted and dismounted.
Further, in this embodiment, a constitution in which the engaging arm 42 is swingable in the left-right direction X, and therefore, even in the case where a force in the left-right direction X acts on the feeding cassette 1 in the mounted state of the feeding cassette 1, description that a degree of the creep deformation of the engaging arm 42 can be decreased will be made.
As an example of the force in the left-right direction X acting on the feeding cassette 1 in the mounted state of the feeding cassette 1, it is possible to cite an urging member used in a mechanism for moving the roller member for sheet feeding (conveyance) in interrelation with the mounting and dismounting of the feeding cassette 1. An urging spring 4 shown in
Here, the pick-up roller 7 is rotatably held by a roller holder 18, and the roller holder 18 is swingably supported by the frame of the printer main body 201A, so that the retard roller 7 is constituted so as to be capable of being raised and lowered (capable of being contacted to and spaced from the sheet). Further, the retard roller 7 is rotatably supported by a roller holder 17, and the roller holder 17 is swingably supported by the frame of the printer main body 201A, so that the retard roller 7 is capable of being contacted to and spaced from the feed roller 9.
Further, each of the roller holders 18 and 17 is constituted so as to move in interrelation with the roller spacing lever 3. That is, in the state in which the feeding cassette 1 is mounted in the printer main body 201A, the portion-to-be-pressed 3a is pressed by the pressing portion 2d, so that the roller spacing lever 3 is held in a position of
Incidentally, as a mechanism for moving the roller holders 18 and 17 in interrelation with the roller spacing lever 3, a known mechanism is applicable. For example, as disclosed in JP-A 2018-80047, the roller holder 17 is swung by pressing the portion-to-be-pressed, provided on the roller holder 17, by the roller spacing lever 3, and the roller holder 18 is swung by another lever member pressed by the roller spacing lever 3. Further, the roller spacing lever 3 and the urging spring 4 shown in
Incidentally, in the mounted state of the feeding cassette 1, by the urging force of the urging spring 4, the roller spacing lever 3 presses the feeding cassette 1 toward the left side (in the direction X2 opposite to the feeding direction X1 of the sheet P) in
On the other hand, in this embodiment, a constitution in which positioning of the feeding cassette 1 with respect to the left-right direction X is carried out by the rear-side positioning mechanism 30 and the front-side positioning mechanism 33 and in which the engaging arm 42 is made swingable in the left-right direction X is employed. For this reason, the urging force of the urging spring 4 can be received by the rear-side positioning mechanism 30 and the front-side positioning mechanism 33, so that the possibility of the occurrence of the creep deformation at the claw portions 42a of the engaging arm 42 can be reduced. That is, according to this embodiment, in the case where the urging member is used as a part of the mechanism for moving the roller member in interrelation with the mounting and dismounting of the feeding cassette 1, it is possible to reduce the possibility that the creep deformation of the engaging member due to the urging force of the urging member occurs.
Here, a mounting constitution of the engaging arm 42 to the feeding cassette 1 will be described using parts (a) and (b) of
As shown in part (b) of
Incidentally, the connecting pin 50 inserted in the connecting hole 51 is fixed in the cassette frame 2 by an unshown snap-fitting constitution. Further, by pressing the connecting pin 50 from below in an arrow C direction, the connecting pin 50 can be easily dismounted from the cassette frame 2. That is, the connecting pin 50 is capable of being mounted in and dismounted from the feeding cassette 1.
As an embodiment 2, a constitution example in which the engaging arm 42 as the engaging member is disposed in the printer main body 201A and in which the boss member 41 as the member-to-be-engaged is disposed in the feeding cassette 1 will be described. In the following, elements represented by reference numerals or symbols common to the embodiments 1 and 2 have substantially the same constitutions and actions, and in this embodiment, a portion different from the embodiment 1 will be described.
As shown in
Even when such a constitution is employed, by engagement between the engaging arm 42 and the boss member 41, a pulled-in function of the feeding cassette 1 and a positioning function of the feeding cassette 1 with respect to the mounting and dismounting direction Y can be obtained. Further, a variation in positional relationship between members due to the part tolerance and assembling tolerance and the like is absorbed by the engaging arm 42 swingable in the direction crossing the mounting and dismounting direction Y, and therefore, degrees of deformation and breaking of the members can be reduced. Further, a possibility of occurrence of creep deformation of the engaging member due to the urging force of the urging member can be reduced.
In the embodiments 1 and 2, the cylindrical boss member 41 was illustrated as the member-to-be-engaged, but for example, a member-to-be-engaged with a polygonal shape or a spindle shape as viewed from above may also be used. That is, an arbitrary shape such that a portion-to-be-locked is provided on an upstream side of the mounting direction Y2 and that a portion narrower in width than the portion-to-be-locked crossing perpendicular to the mounting direction Y2 is provided can be used. Further, the engaging member can receive the portion-to-be-locked by a locking portion by utilizing elasticity, and after reception, the portion-to-be-locked may only be required to generate a mechanical retaining force for restricting getting out of the portion-to-be-locked, so that the shape of the engaging member is not limited to the shape illustrated in part (a) of
In the embodiments 1 and 2, as the portion-to-be-positioned, the substantially cylindrical positioning shafts 31 and 34 extending in the mounting direction Y2 of the feeding cassette 1 was illustrated, but as the portion-to-be-positioned, one with a polygonal shape or a flat plate-like member extending so as to cross the left-right direction X may also be used. In this case, the positioning portion may only be required to change in shape to an appropriate shape capable of restricting a positional deviation with respect to the left-right direction X of the feeding cassette 1. Further, the positioning shafts 31 and 34 may be provided in the printer main body 201A, and the bearing portions 32 and 35 may also be provided in the feeding cassette 1.
In the above-described embodiments, the sheet feeding device provided as a part of the printer 201 as the image forming apparatus was described, but the present invention may also be applied to a sheet feeding device (option feeder) used in connection to the printer, for example. In that case, the apparatus main assembly refers to an apparatus main assembly (portion excluding the sheet accommodating portion) of the sheet feeding device other than the printer.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2020-155237 filed on Sep. 16, 2020, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-155237 | Sep 2020 | JP | national |
