Patent Application
20200019113
This application is based upon and claims the benefit of priority from the corresponding Japanese Patent Application No. 2018-131393 filed on Jul. 11, 2018, the entire contents of which are incorporated herein by reference.
The present disclosure relates to an image forming apparatus and more particularly to an image forming apparatus which includes a sheet storage cassette that is removable with respect to a cassette fitting portion in the main body of the image forming apparatus.
In an image forming apparatus such as a copying machine or a printer, a paper feed cassette (sheet storage cassette) is used in order to feed paper such as cut paper. In the paper feed cassette, a large number of sheets before printing are previously stocked in a sheet storage portion. The sheets stacked within the paper feed cassette are separated and supplied one by one from the uppermost layer with a paper feed roller, a pickup roller and the like provided in the vicinity of the paper feed cassette.
Conventionally, in a paper feed cassette, a lift plate is provided in which sheets are placed on its upper surface and which raises and lowers a sheet stack. In the lift plate, an upstream end in the feed direction is supported to the inner side of the bottom surface of the paper feed cassette. The lift plate can be turned about the supporting point of the upstream end in the feed direction with an end portion on the downstream side in the feed direction serving as a turning end. In the paper feed cassette, a lift mechanism is also provided which raises and lowers the turning end of the lift plate. A drive force is transmitted to the lift mechanism through a main body gear provided in the main body of the image forming apparatus, an input gear provided in the cassette side surface portion of the paper feed cassette and the like.
Incidentally, the lift plate affects the accuracy of paper feed, and thus the accuracy of the position is required. However, in the conventional image forming apparatus, the lift plate is provided in the paper feed cassette. Hence, both the accuracy of the position of the lift plate with respect to the sheet storage portion of the paper feed cassette and the accuracy of the position of the sheet storage portion with respect to the main body of the image forming apparatus are required.
In the lift plate, the sheet stack is raised and lowered, and thus rigidity is required. In the conventional image forming apparatus, the lift plate is provided in the paper feed cassette, and thus for the paper feed cassette which supports the lift plate, rigidity is also required. Hence, the weight of the paper feed cassette is increased, and thus the operability thereof by a user is lowered.
An image forming apparatus of the present disclosure includes: a cassette fitting portion which is provided in the main body of the apparatus and which includes a feed portion that feeds a sheet; and a sheet storage cassette which can be fitted to the cassette fitting portion along the sheet feed direction and which includes a sheet storage portion that stores the sheet, in the cassette fitting portion, a lift plate is provided which is arranged below an end portion of the sheet storage cassette fitted to the cassette fitting portion on a downstream side in the sheet feed direction and which raises and lowers the sheet, the sheet storage portion includes a cassette base in which the sheet is stacked on an upper surface and a side wall which is provided so as to stand from end portions of the cassette base on the downstream side, in the cassette base, an opening portion is formed in a position opposite the lift plate and in a state where the sheet storage cassette is fitted to the cassette fitting portion, the lift plate is arranged selectively either in a lowered position in which the lift plate is arranged below the cassette base and in which the sheet storage cassette is removable with respect to the cassette fitting portion or in a raised position in which the lift plate is protruded above the cassette base through the opening portion so as to allow the sheet to be fed with the feed portion.
Further features and advantages of the present disclosure will become more apparent from the description of an embodiment given below.
An embodiment of the present disclosure will be described below with reference to drawings.
An image forming apparatus 100 according to the embodiment of the present disclosure will be described with reference to
In the image forming portion P, along the direction of rotation of a photosensitive drum 2 (counterclockwise direction in
Sheets 18 which are stored in a paper feed cassette (sheet storage cassette) 30 are transported through a sheet transport path 11 and a registration roller pair with predetermined timing. In the image forming portion P in which a toner image is formed, the toner image on the surface of the photosensitive drum 2 is transferred to the sheet 18 with the transfer roller. The sheet 18 to which the toner image is transferred is separated from the photosensitive drum 2, is transported to a fixing portion and is heated and pressurized, and thus the toner image is fixed to the sheet 18.
The sheet 18 which is passed through the fixing portion is switched in the direction of transport with a branch portion which is branched into a plurality of directions. Then, the sheet 18 is ejected with an ejection roller pair 14 to an ejection tray 15 without being processed (or after being fed to a double-sided transport path where double-sided printing is performed).
The paper feed cassette 30 is formed so as to be removable with respect to a cassette fitting portion 1 in the main body of the image forming apparatus 100. In the image forming apparatus 100, on the downstream side in the feed direction (the sheet feed direction, the direction of an arrow A) of the paper feed cassette 30, the sheet transport path 11 is provided which is used when the sheet is fed from below the main body of the image forming apparatus 100. Hence, the paper feed cassette 30 is pulled out in the leftward direction of
In an opposite portion opposite part of the cassette fitting portion 1 on the downstream side in the direction of fitting of the paper feed cassette 30 (the right side of
The pickup roller 21 is pressed to the uppermost surface of the sheets 18 stacked in the paper feed cassette 30 and is rotated so as to feed out the sheet 18. The feed roller 22a transports the sheet 18 fed out from the pickup roller 21. A retard roller 22b is pressed to the feed roller 22a, and these two rollers form a transport roller pair 22.
When a plurality of sheets 18 are simultaneously fed with the pickup roller 21, the sheets 18 are separated with the transport roller pair 22. In this way, only the uppermost sheet 18 is fed out toward the sheet transport path 11.
In
On the outer sides of the side walls 32b and 32c parallel to the direction in which the paper feed cassette 30 is fitted and the direction in which the paper feed cassette 30 is pulled out (the directions of arrows AA'), a pair of cassette rails 33 is additionally provided. On the side of the main body of the image forming apparatus 100, a pair of main body rails 44 (see
Within the paper feed cassette 30, a pair of width regulation cursors 35 is provided so as to stand along the feed direction (the direction of the arrow A). The pair of width regulation cursors 35 can be moved toward each other in the sheet width direction orthogonal to the feed direction, and make contact with the side surfaces of a sheet stack from both sides in the sheet width direction so as to locate the sheet stack in the sheet width direction thereof.
On the upstream side in the feed direction within the paper feed cassette 30, a back end regulation cursor 36 is provided such that the back end regulation cursor 36 can be moved along the feed direction. The back end regulation cursor 36 makes contact with the back end surface of the sheet stack from the upstream side in the feed direction so as to locate the sheet stack in the feed direction.
Although in the cassette base 31, slits and the like for allowing the movements of the width regulation cursors 35 and the back end regulation cursor 36 are provided, they are omitted for the simplification of the drawings.
Here, in the present embodiment, in a position opposite a lift plate 50 of the cassette base 31 which will be described later, an opening portion 31a is formed through which at least part of the lift plate 50 can be passed.
In an edge portion of the opening portion 31a on the downstream side in the feed direction, a pair of tip end support portions (support protrusion portions) 31b is provided which are protruded to the upstream side in the feed direction. The tip end support portions 31b are arranged a predetermined distance apart in the sheet width direction so as to support tip end edge portions of the sheets 18. In edge portions of the opening portion 31a in the sheet width direction, a pair of corner support portions 31c is provided which are protruded inward in the sheet width direction so as to support the tip end corner portions of the sheets 18. As will be described in detail later, the tip end support portions 31b and the corner support portions 31c form a step portion 31d.
In the present embodiment, as shown in
Specifically, as shown in
For the simplification of the drawings, only one of the main body frames 41 is drawn. Although the main body frame 41 is formed so as to be extended from the downstream end to the upstream end of the paper feed cassette 30, the part on the upstream side is omitted. Although the main body frame 42 is formed so as to connect the pair of main body frames 41, part thereof is omitted.
The main body frame 41 includes a side surface portion 41a (a main body side surface) and a bottom surface portion 41b which is protruded from lower end a portion of the side surface portion 41a inward in the sheet width direction. In a predetermined position of the side surface portion 41a, a shaft portion 43 is fixed which serves as the center of the turning of the lift plate 50. In a connection portion of the side surface portion 41a and the bottom surface portion 41b, the main body rail 44 described above is provided.
The main body frame 42 includes a side surface portion 42a and a bottom surface portion 42b which is protruded from a lower end portion of the side surface portion 42a to the upstream side in the feed direction. The side surface portion 42a makes contact with the side wall 32a of the paper feed cassette 30 so as to locate the paper feed cassette 30. The bottom surface portion 42b supports the push-up plate 62 of a lift mechanism 60 which will be described later.
The lift plate 50 is formed of sheet metal, and includes a sheet support portion 51, a pair of arm portions 52 and a pair of joint portions 53. The sheet support portion 51 supports the sheets 18. The pair of arm portions 52 is provided so as to stand on both end portions of the sheet support portion 51 in the sheet width direction, and is supported to the shaft portions 43 of the cassette fitting portion 1 such that the pair of arm portions 52 can be turned. The pair of joint portions 53 connects both the end portions of the sheet support portion 51 in the sheet width direction and the pair of arm portions 52.
The sheet support portion 51 is formed so as to be smaller than the opening portion 31a of the cassette base 31. The joint portions 53 are formed so as to be extended to the outer sides of the side walls 32b and 32c of the paper feed cassette 30 in the sheet width direction. The arm portions 52 are arranged on the outer sides of the paper feed cassette 30 in the sheet width direction. The lift plate 50 is turned about the shaft portions 43 with the downstream end thereof in the feed direction serving as a turning end.
In an edge portion of the sheet support portion 51 on the downstream side in the feed direction, slits 51a (see
As shown in
In the cassette fitting portion 1, the lift mechanism 60 is arranged which raises and lowers the downstream end of the lift plate 50 in the feed direction. The lift mechanism 60 is arranged in a space S31 (see
As shown in
The turning shaft portion 61 penetrates a fixing hole 62a of the push-up plate 62 on one end, and thus the push-up plate 62 is fixed to the turning shaft portion 61. The push-up plate 62 is arranged in a position opposite a substantially center portion of the back surface of the lift plate 50 in the sheet width direction. As shown in
As shown in
When the paper feed cassette 30 is fitted or removed or when a non-image formation operation is performed, the sector gear 63 of the lift mechanism 60 is rotated in the backward direction by the drive mechanism 70. In this way, the push-up plate 62 is held in a state (the state of
On the other hand, when an image formation operation is performed, the sector gear 63 of the lift mechanism 60 is rotated in the forward direction by the drive mechanism 70. In this way, the push-up plate 62 is held in a state (the state of
In the present embodiment, as described above, the lift plate 50 for raising and lowering the sheets 18 is provided in the cassette fitting portion 1. In this way, as compared with a case where the lift plate 50 is provided in the paper feed cassette 30, the accuracy of the position of the lift plate 50 can easily be enhanced.
Specifically, in the case where the lift plate 50 is provided in the paper feed cassette 30, both a displacement error in the lift plate 50 with respect to the sheet storage portion S of the paper feed cassette 30 and a displacement error in the sheet storage portion S with respect to the main body of the image forming apparatus 100 are produced. On the other hand, in the present embodiment, the lift plate 50 is provided in the cassette fitting portion 1 of the main body of the image forming apparatus 100, and thus only a displacement error in the lift plate 50 with respect to the main body of the image forming apparatus 100 is produced. Hence, the accuracy of the position of the lift plate 50 can easily be enhanced.
The lift plate 50 is provided in the cassette fitting portion 1, and thus unlike the case where the lift plate 50 is provided in the paper feed cassette 30, the lift plate 50 is not supported by the paper feed cassette 30. Hence, it is not necessary to enhance the rigidity of the paper feed cassette 30. Thus, it is possible to reduce the weight of the paper feed cassette 30, and consequently, the operability of the paper feed cassette 30 by a user can be enhanced.
As compared with the case where the lift plate 50 is provided in the paper feed cassette 30, the structure of the paper feed cassette 30 can be simplified. Hence, the weight of the paper feed cassette 30 can be more reduced, and thus the operability of the paper feed cassette 30 by the user can be more enhanced.
The lift mechanism 60 is provided in the cassette fitting portion 1, and thus unlike a case where the lift mechanism 60 is provided in the paper feed cassette 30, it is not necessary to provide members such as a gear for transmitting a drive force from the side of the main body of the image forming apparatus 100 to the side of the paper feed cassette 30. Hence, it is possible to reduce the cost of the image forming apparatus 100.
As described previously, in the edge portion of the opening portion 31a on the downstream side in the feed direction, the tip end support portions 31b are provided which are protruded to the upstream side in the feed direction so as to support the edge portions of the sheets 18. In this way, the drop of the sheets 18 from the opening portion 31a can easily be reduced. In the edge portion of the lift plate 50 on the downstream side in the feed direction, the slits 51a through which the tip end support portions 31b can be passed are formed in the parts opposite the tip end support portions 31b. In this way, while the lift plate 50 is being prevented from colliding with the tip end support portions 31b, the tip ends of the sheets 18 can be supported by the lift plate 50.
As described previously, the joint portions 53 of the lift plate 50 are formed so as to be extended to the outer sides of the side walls 32b and 32c of the paper feed cassette 30 in the sheet width direction. The arm portions 52 are arranged on the outer sides of the paper feed cassette 30 in the sheet width direction. In this way, while the lift plate 50 is being supported by the main body of the image forming apparatus 100 such that the lift plate 50 can be turned, the lift plate 50 can easily be arranged in the lowered position and in the raised position.
It should be considered that the embodiment disclosed herein is illustrative in all respects and not restrictive. The scope of the present disclosure is indicated not by the description of the embodiment discussed above but by the scope of claims, and furthermore, meanings equivalent to the scope of claims and all modifications within the scope are included.
For example, although the example where the present disclosure is applied to the monochrome printer is described, the present disclosure is not limited to this example. Needless to say, the present disclosure can be applied to various image forming apparatuses, such as a color printer, a monochrome copying machine, a color copying machine, a digital copying machine and a facsimile machine, which include a sheet storage cassette.
Although in the embodiment discussed above, the example where the push-up plate 62 is used to raise and lower the lift plate 50 is described, the lift plate 50 may be raised and lowered without use of the push-up plate 62. For example, the shaft portion 43 is formed such that the shaft portion 43 can be rotated with respect to the side surface portion 41a of the main body frame 41, the lift plate 50 is fixed to the shaft portion 43 and an input gear (unillustrated) is fixed to the end portion of the shaft portion 43. Then, the gears 71 of the drive mechanism 70 may be connected to the input gear. In this case, the lift mechanism is formed with the shaft portion 43 and the input gear.
For example, a compression spring (unillustrated) which biases the back surface of the lift plate 50 upward and a pressing member which is formed with an eccentric cam capable of pressing the lift plate 50 downward and the like may be used so as to raise and lower the lift plate 50. In this case, the compression spring, the pressing member and the like form the lift mechanism.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-131393 | Jul 2018 | JP | national |
