Patent Application
20120256367
1. Field of the Invention
The present invention relates to a sheet feeding apparatus which feeds a sheet stacked on a sheet stacking portion to an image forming portion and an image forming apparatus including the same.
2. Description of the Related Art
Some of conventional image forming apparatuses such as a printer, a copying machine, and a facsimile include a sheet feeding apparatus which feeds a sheet to an image forming portion. Such a sheet feeding apparatus is configured to stack a sheet on a sheet stacking table arranged in a storing portion to enable lifting and lowering, lift the sheet stacking table to a position enabling sheet feeding, and thereafter send the sheet toward the image forming portion by a feeding roller.
For example, the sheet feeding apparatus is provided with a sheet surface detecting sensor which detects a height position of an uppermost sheet stacked on the sheet stacking table. This sheet surface detecting sensor is OFF when the uppermost sheet is at a height position enabling feeding and ON when the uppermost sheet is lower than the height position enabling feeding, for example.
When the sheet surface detecting sensor is ON, a controller is configured to drive a motor, e.g., to rotate a reel drum, and reel a wire attached to the sheet stacking table. This causes the sheet stacking table to lift, and when the uppermost sheet reaches the height position enabling feeding, the sheet surface detecting sensor is OFF to stop driving, and the sheet stacking table stops. This operation is repeated during sheet feeding to maintain the uppermost sheet at the height position enabling sheet feeding.
A recent requirement for improvement in efficiency of physical distribution promotes reduction in size and weight of packing materials, which brings about a tendency toward an increase in vibration and impact applied to an apparatus main body at the time of transporting the image forming apparatus including the sheet feeding apparatus. Thus, the sheet stacking table of the sheet feeding apparatus may be vibrated and damaged, and the sheet stacking table may collide with the feeding roller which feeds a sheet and break the roller portion.
To deal with this, a configuration is proposed in the sheet feeding apparatus, in which a lock member for transportation is provided to lock the sheet stacking table to prevent scratches and breakage caused by vibration and impact at the time of transportation. This sheet feeding apparatus has a lift hole vertically penetrating the sheet stacking table provided to be vertically movable on an accommodating surface accommodating a sheet and has a locking hole penetrating the lift hole and an opposed part on the accommodating surface when a lift plate is located along the accommodating surface. At the time of transportation, a stopper as the lock member is engaged with the lift hole and the locking hole, and a supporting plate of the stopper presses the sheet stacking table to prevent the sheet stacking table from moving upward from the accommodating surface and regulates unnecessary movement of the sheet stacking table (refer to Japanese Patent Laid-Open No. 2007-197204).
However, in a case of using the lock member for transportation, the lock member needs to be attached at the time of assembly and inevitably needs to be detached before use by a user. In this case, an attaching and detaching work of the lock member is required and is troublesome. In addition, in a case where detachment of the lock member is omitted before use, the sheet stacking table is lifted in a state where the lock member is attached, which may cause scratching and breakage of the sheet stacking table and peripheral members.
The present invention provides a sheet feeding apparatus which enables simple and reliable locking of a sheet stacking portion at the time of transportation and which enables extremely simple unlocking at the time of use and an image forming apparatus including the same.
The present invention provides a sheet feeding apparatus including a storing portion which has a sheet stacking portion to enable lifting and lowering, a feeding portion which feeds a sheet stacked on the sheet stacking portion, a lifting and lowering mechanism which lifts and lowers the sheet stacking portion, and a controller which controls the lifting and lowering mechanism. The lifting and lowering mechanism includes an abutting portion which makes the lifting sheet stacking portion abut thereon at a predetermined position and makes the sheet stacking portion lockable with respect to the storing portion, a pulse motor which is a driving source of the lifting and lowering mechanism, and a one-way clutch which is provided between the pulse motor and the sheet stacking portion, is rotated freely in a lifting direction of the sheet stacking portion, and is locked in rotation in a lowering direction of the sheet stacking portion. The controller drives the pulse motor to be rotated in the lifting direction of the sheet stacking portion, further drives the pulse motor to be rotated in the same direction even after the sheet stacking portion abuts on the abutting portion to cause the pulse motor to step out, and thereafter renders the pulse motor non-conductive, thus to cause the sheet stacking portion to be locked by the one-way clutch in a state where the sheet stacking portion abuts on the abutting portion.
The present invention provides a sheet feeding apparatus including a storing portion which has a sheet stacking portion to enable lifting and lowering, a feeding portion which feeds a sheet stacked on the sheet stacking portion, a pulse motor which lifts and lowers the sheet stacking portion, an abutting portion which makes the sheet stacking portion lifted by the pulse motor abut thereon at a predetermined position and makes the sheet stacking portion lockable with respect to the storing portion, a one-way clutch which is provided between the pulse motor and the sheet stacking portion, is rotated freely in a lifting direction of the sheet stacking portion, and is locked in rotation in a lowering direction of the sheet stacking portion, and a controller which drives the pulse motor to be rotated in the lifting direction of the sheet stacking portion, further drives the pulse motor to be rotated in the same direction even after the sheet stacking portion abuts on the abutting portion to cause the pulse motor to step out, and thereafter renders the pulse motor non-conductive.
With a sheet feeding apparatus and an image forming apparatus according to the present invention, a sheet stacking portion can be locked reliably with a simple operation without use of a lock member or the like at the time of transportation. This dispenses with a troublesome operation such as attaching and detaching the lock member and can prevent breakage caused by omission of detachment of the lock member reliably.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Hereinafter, embodiments of the present invention will be described in details with reference to the drawings.
As illustrated in
The apparatus main body 10 includes a controller 5 which overall controls respective portions of the image forming apparatus 1 including the sheet deck 2 and an image forming portion 3 which performs image formation to a sheet by an electrophotographic system. It is to be noted that, although the controller 5 is described as one provided for the entire image forming apparatus 1 including the sheet deck 2 in the present embodiment, the present embodiment is not limited to this. The controller 5 can be a controller configured to separate the image forming apparatus 1 into the image forming portion 3 and the sheet feeding portion 4, and the sheet deck 2.
As for feeding control, the controller 5 performs control based on information of after-mentioned sheet surface detecting flag 62 and sheet surface detecting sensor 63 so that the height of the uppermost sheet stacked on a sheet stacking table 52 may be a height enabling feeding.
The image forming portion 3 includes a photosensitive drum 14 which forms a toner image, a laser scanner 12 which irradiates the photosensitive drum 14 with light corresponding to an image signal, and a transfer roller 15 which transfers the toner image formed by the photosensitive drum 14 to a sheet S. To the image forming portion 3 is fed the sheet S from the sheet feeding portion 4 or the sheet deck 2 by the control of the controller 5 for image formation.
When an image forming operation is started in the image forming portion 3 configured as above, the laser scanner 12 first irradiates the photosensitive drum 14 with light corresponding to an image signal to form an electrostatic latent image on the photosensitive drum 14. Subsequently, the electrostatic latent image is developed with a toner stored in a toner cartridge 13 to cause the toner image (visible image) to be formed on the photosensitive drum 14.
Also, when a sheet S is fed from the sheet deck 2 as described later at the same time as such a toner image forming operation, the sheet S is conveyed to a transfer portion 28 by a conveying roller 11 and a registration roller 11A in synchronization with the image formed on the photosensitive drum 14. The transfer portion 28 includes the photosensitive drum 14 and the transfer roller 15 and is configured to transfer the toner image to the sheet S by applying a bias voltage to the transfer roller 15.
The sheet S to which the toner image has been transferred is thereafter conveyed to a fixing portion 16, is heated at this fixing portion 16 to have the toner image fixed thereon, and is further discharged to a discharging portion 18 at the upper portion of the apparatus main body 10 by a discharge roller 17.
The sheet deck 2 includes in a storing portion 61 the sheet stacking table 52 as a sheet stacking portion configured to enable to stack the sheet bundle (S) and to enable lifting and lowering, a feeding roller 54, a pair of separating rollers 66, and a conveying roller 57. In the storing portion 61 are further provided after-mentioned reference-side side regulating member 58, non-reference-side side regulating member 59, and rear-end regulating member 60. The feeding roller 54 acts as a feeding portion which feeds a sheet stacked on the sheet stacking table 52.
The pair of separating rollers 66 includes a feed roller 55 and a retard roller 56 which separate a sheet S sent from the feeding roller 54. The conveying roller 57 conveys to the apparatus main body 10 the sheet S separated and fed one by one by the pair of separating rollers 66. An after-mentioned pulse motor (stepping motor) 27 is illustrated in
The sheet surface detecting flag 62 is formed in an L shape as seen from the side surface (refer to
Also, the sheet stacking table 52 has the wire hanging portions 64a and 64b formed to protrude outward from both the side portions of the cutout portion 52a and the wire hanging portions 64c and 64d formed to protrude outward from both the side portions of the cutout portion 52b. The wire hanging portions (at least parts of the sheet stacking portion) 64a, 64b, 64c, and 64d respectively movably pass through and are engaged with the opposed guide grooves 65a, 65b, 65c, and 65d. The sheet stacking table 52 is made of, e.g., a synthetic resin material, and the wire hanging portions 64a to 64d are made of the same material.
To each of the wire hanging portions 64a, 64b, 64c, and 64d is attached one end of each of wires 51a, 51b, 51c, and 51d as flexible members. The other end of each of the wires 51a to 51d is attached to each of pulleys 21 and 21 fixedly mounted respectively on both the end portions of a wire reel shaft 53 extending in a width direction of the sheet stacking table 52 to enable reeling.
As illustrated in
In the present embodiment configured as above, when the pulse motor (driving source) 27 is driven based on a selected mode by control of the controller 5, the wire reel shaft 53 is rotated in a predetermined rotating direction and at predetermined rotating speed. As a result, the wire hanging portion 64a is reeled in or out by the wire 51a, the wire hanging portion 64b is reeled in or out by the wire 51b, the wire hanging portion 64c is reeled in or out by the wire 51c, and the wire hanging portion 64d is reeled in or out by the wire 51d. Thus, the sheet stacking table 52 performs a lifting and lowering operation with the cutout portions 52a, 52b, and 52c respectively along the reference-side side regulating member 58, the non-reference-side side regulating member 59, and the rear-end regulating member 60.
Here, a configuration to lock the sheet stacking table 52 at the time of transporting the image forming apparatus will be described in details.
As illustrated in
All of the wire hanging portions 64a to 64d are located on the same level at both the side portions of the sheet stacking table 52. All of the abutting portions 101a to 101d are formed to be located on the same level in the storing portion 61 so as to receive equal abutting forces respectively from the corresponding wire hanging portions 64a to 64d. These abutting portions 101a to 101d are formed by bending outward parts corresponding to the uppermost portions of the respective guide grooves 65a to 65d in the frame plates 19 and 20 made of metals or the like. Alternatively, in a case where the frame plates 19 and 20 are made of synthetic resin materials, the abutting portions 101a to 101d are formed integrally with the guide grooves 65a to 65d by injection molding or the like.
The abutting portions 101a to 101d are provided to enable to abut on the sheet stacking table 52 and regulate movement of the sheet stacking table 52 at the aforementioned lock position, which is a position further above the height of the sheet stacking table 52 by control of the controller 5. The pulse motor 27, an after-mentioned one-way clutch 40, the guide grooves 65a to 65d, and the abutting portions 101a to 101d act as a lifting and lowering mechanism whose lifting and lowering driving is controlled by the controller 5.
At each end portion of the wire reel shaft 53 is disposed a driving unit 30 which rotates the wire reel shaft 53 to lift the sheet stacking table 52 to a position enabling sheet feeding and holds the sheet stacking table 52 at this position enabling sheet feeding as illustrated in
The driving unit 30 includes the pulse motor 27, four stage gears 31a, 31b, 31c (including 31e), and 31d which transmit rotation of a motor gear 27a to the wire reel shaft 53, and a driving releasing member 32, as illustrated in
The driving unit 30 includes a detecting sensor 37 as a photo interrupter at a position at which turning (swing) of a lower end portion 32a of the driving releasing member 32 can be detected. Also, the stage gear 31d is coaxially connected to the wire reel shaft 53 having the pulley 21 at an end portion thereof as illustrated in
The stage gear 31a has built therein the one-way clutch 40 (
When the door 2A (
This releases transmission of driving of the pulse motor 27 to the wire reel shaft 53, along with which holding of the sheet stacking table 52 by the one-way clutch 40 of the driving unit 30 is released to cause the wire reel shaft 53 to be rotatable. As a result, by weight of the sheet S stacked on the sheet stacking table 52 and the sheet stacking table itself applied to the wire reel shaft 53 via the wires 51a to 51d, the wire reel shaft 53 is rotated in a direction of reeling out the wires 51a to 51d. Thus, the sheet stacking table 52 is lowered to a lowermost stacking position.
Subsequently, when stacking of the sheet bundle (S) to the sheet stacking table 52 at the stacking position is finished, and the door 2A is closed, the driving releasing member 32 is pressed by a thrusting portion (not shown) provided at the door 2A and is turned to a direction of arrow A in
When the detecting sensor 37 detects the turning of the driving releasing member 32, the controller 5 drives the pulse motor 27 to be rotated in a lifting direction of the sheet stacking table 52 based on a detection signal from the detecting sensor 37. Thus, the wire reel shaft 53 is rotated in a direction of reeling in the wires, the wires 51a, 51b, 51c, and 51d are reeled in by the pulleys 21 and 21, and the sheet stacking table 52 is lifted.
At this time, the controller 5, which drives the pulse motor 27 to be rotated in the lifting direction, further drives the pulse motor 27 to be rotated in the same direction even after the wire hanging portions 64a to 64d as parts of the sheet stacking table 52 abut on the abutting portions 101a to 101d to cause the pulse motor 27 to step out and thereafter renders the pulse motor 27 non-conductive. As a result of this, the sheet stacking table 52 is locked by the one-way clutch 40 in a state where the wire hanging portions 64a to 64d abut on the abutting portions 101a to 101d.
As illustrated in
Further, as illustrated in
In this case, the controller 5 retracts the feeding roller 54 above the sheet stacking table 52, and in the retracting state, the controller 5 leaves a predetermined space Z2 between the feeding roller 54 and the sheet stacking table 52. In other words, the abutting portions 101a to 101d function not to make the sheet stacking table 52 abut on the feeding roller 54 in a state where the wire hanging portions 64a to 64d of the sheet stacking table 52 abut thereon. In this manner, respective positions are set so as to prevent scratches and breakage to the feeding roller 54 caused by vibration and impact at the time of transportation.
Also, the controller 5 performs control in the following different modes when the opened door 2A is closed depending on an operating state of a not shown manual switch arranged in the apparatus main body 10.
That is, as for the characteristics of the pulse motor 27, the higher the number of times of rotation of the pulse motor 27 is, the more the torque of the motor is lowered, as illustrated in the graph in
The controller 5 also has a shipping mode (lock mode) in which the pulse motor 27 is rotated with a higher number of times of rotation than that at the time of actual use in the normal mode (feeding mode), and the number of times of rotation and the torque at this time are set as “b” in
In this manner, the controller 5 has the normal mode for normal control, which is used at the time of sheet feeding by the feeding roller 54, and the shipping mode for accelerating control, in which the sheet stacking table 52 is lifted fast with lower torque and faster rotation than those in the feeding mode, so as to be switchable. The controller 5 drives the pulse motor 27 to be rotated until the pulse motor 27 steps out at the time of switching the mode to the shipping mode. Switching between the modes is performed by an operation of the aforementioned manual switch (not shown).
In the present embodiment configured as above, when the door 2A is opened as in
Subsequently, when the aforementioned manual switch is switched to the normal mode side, sheet refilling to the sheet stacking table 52 is finished, and the door 2A is closed, the controller 5 drives the pulse motor 27 in a reel-in direction with the number of times of rotation and the torque shown as “a” in
Thereafter, when the uppermost sheet S1 of the sheet bundle (S) stacked on the sheet stacking table 52 abuts on the sheet surface detecting flag 62 as illustrated in
At this time, the feeding roller 54 abuts on the uppermost sheet of the sheet bundle (S) and is rotated in a feeding direction based on a sent feeding signal as illustrated in
In this manner, the feeding roller 54 moves to a feeding position (
On the other hand, at the time of transportation such as the time of factory shipment, the door 2A is opened to lower the sheet stacking table 52 to the lowermost position. The sheet bundle is removed in a case where the sheet bundle exists on the sheet stacking table 52, and the aforementioned manual switch is switched to the shipping mode side. When the door 2A is closed in this state, the controller 5 drives the pulse motor 27 in a reel-in direction of the wire reel shaft 53 with the number of times of rotation and the torque shown as “b” in
Subsequently, when the sheet stacking table 52 is lifted, and the wire hanging portions 64a to 64d abut on the abutting portions 101a to 101d, the pulse motor 27, which attempts to be rotated further in the same direction, steps out. However, since the torque at this time is minimum necessary torque in a state where there is no sheet on the sheet stacking table 52, forces applied to the wire hanging portions 64a to 64d and the abutting portions 101a to 101d are minor, and the abutment has no problem.
In this manner, by switching the mode to the shipping mode, the pulse motor 27 is driven to be rotated until the pulse motor 27 steps out at the lock position exceeding upward the moving range of the sheet stacking table 52 at the time of sheet surface control by the controller 5, and thus the sheet stacking table 52 can be locked reliably. Accordingly, at the time of shipment, the sheet stacking table 52 can be locked easily and reliably only with the control of the pulse motor 27. Thus, scratches and breakage caused by vibration and impact at the time of transportation in a state of building the sheet deck 2 in the image forming apparatus 1 or in a state of the sheet deck 2 alone can be prevented by a simple configuration that does not cause a cost increase. Also, at this time, since the sheet surface detecting sensor 63 is in a state of sheet residing, the sheet stacking table 52 will not be lifted further even when a user turns on main power in this state. Accordingly, the sheet stacking table 52 or peripheral members will not be scratched or broken when the sheet stacking table 52 is lifted.
Also, in a case where the apparatus is first used after transportation, when the door 2A is opened by the user, the controller 5 detects the opening, and the driving releasing member 32 is turned by the hooking portion (not shown), and mesh between the stage gear 31b and the stage gear 31c (31e) is released. By doing so, holding of the sheet stacking table 52 by the one-way clutch 40 is released, and by weight of the sheet stacking table itself, the wire reel shaft 53 is rotated in a direction of reeling out the wires 51a to 51d, and the sheet stacking table 52 is lowered to the lowermost stacking position.
Subsequently, when stacking of the sheet bundle to the sheet stacking table 52 is finished, the aforementioned manual switch (not shown) is switched to the normal mode side, and the door 2A is closed, the driving releasing member 32 is pressed by the thrusting portion (not shown) at the door 2A, and the stage gear 31b and the stage gear 31c (31e) mesh with each other. Subsequently, when the turning of the driving releasing member 32 is detected at the detecting sensor 37, the controller 5 synchronously rotates the pulse motor 27, which has stepped out, again, and lifts the sheet stacking table 52 via the wires 51a to 51d.
Meanwhile, as described above, although the abutting portions 101a to 101d are made of metals or synthetic resin materials, and the wire hanging portions 64a to 64d are made of synthetic resin materials, these may be made in the following manner instead of this manner. For example, at least either the abutting portions 101a to 101d or the wire hanging portions 64a to 64d may be made of elastic members having elasticity. In this case, the lock state by the abutment between the abutting portions 101a to 101d and the wire hanging portions 64a to 64d can be further stabilized.
In the present embodiment, the sheet stacking table 52 is fixed (locked) by making the pulse motor 27 step out and making the wire hanging portions 64a to 64d abut on the abutting portions 101a to 101d. However, the abutting portions 101a to 101d may be substituted for in a manner of the following modification example.
For example, as illustrated in
Thus, each of the abutting members 102 is in a state where a force is applied by each tension coil spring 104 in a direction in which the upper end portion 102a applies a force to each of the wire hanging portions 64a to 64d of the sheet stacking table 52. Consequently, as in
Also, in the present modification example as well as in the aforementioned embodiment, an elastic force of each abutting member 102 is set so that each abutting member 102 may function not to make the sheet stacking table 52 abut on the feeding roller 54 in a state of abutting each of the wire hanging portions 64a to 64d of the sheet stacking table 52.
Since the sheet stacking table 52 can be locked by the upper end portion 102a due to the elastic force of each abutting member 102, the above configuration is a simple configuration, does not cause a cost increase, and can prevent scratches and breakage caused by vibration and impact at the time of transportation reliably. Also, at this time, since the sheet surface detecting sensor 63 is in a state of sheet residing, the sheet stacking table 52 will not be lifted even when the user turns on power in this state. Accordingly, the sheet stacking table 52 or peripheral members will not be scratched or broken when the sheet stacking table 52 is lifted. Also, the sheet stacking table 52 can be fixed and held at the lock position exceeding upward the moving range without making the pulse motor 27 step out. It is to be understood that the controller 5 has the normal mode and the shipping mode in the present modification example as well.
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. 2011-086661, filed Apr. 8, 2011, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-086661 | Apr 2011 | JP | national |
