Patent Application
20150001784
1. Field of the Invention
The present invention relates to a sheet feeding apparatus which processes sheets on which images are formed.
2. Description of the Related Art
As shown in Japanese Patent Laid-Open No. 2000-219399, conventionally, in an image forming apparatus, a sheet having an image formed thereon may be discharged to the stack tray after performing post-processing such as stapling.
As shown in the figure, in the conventional image forming apparatus, the rear end of the sheet bundle S on the processing tray is pushed in the direction A by the sheet bundle pushing member 60a provided on the belt 60 and the sheet bundle S is discharged on the stack tray.
As shown in
Therefore, when the sheet bundle pushing member 60a is stopped or decelerated immediately before discharging the sheet stack S on to the stacking tray, so-called spring-back is easy to occur in which the sheet bundle S bent when pushed by the sheet bundle pushing member 60a goes back to a flat state.
As shown in
It can be considered that kicking amount of the sheets is reduced by reducing the amount of deflection of the sheets by moving the sheet bundle pushing member 60a slowly. However, this causes a problem where the productivity is lowered.
An object of the present invention is to suppress deflection of a sheet and to prevent stacking ability from being deteriorated when the sheet bundle pops out due to spring-back.
To accomplish this object, a sheet conveying apparatus comprising: a supporting portion which supports a sheet; a sheet conveying portion which includes an abutting portion for abutting against an end portion of the sheet supported by the supporting portion and which conveys the sheet being abutted against the abutting portion by moving in a predetermined moving direction; and a pressing portion which is provided on the sheet conveying portion in such a way that the pressing portion is movable in a thickness direction of the sheet and which presses the sheet toward the supporting portion, wherein the pressing portion includes: an inclined portion arranged in a manner so as to be closer to the supporting portion at an upstream side in the predetermined moving direction than a downstream side in the predetermined moving direction; and a contacting portion configured to contact a surface of the sheet being abutted against the abutting portion to press the sheet to the supporting portion at a position distant from the abutting portion.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Embodiments for carrying out the present invention will be described in detail hereunder with reference to the drawings.
The best mode for carrying out the present invention will be explained in detail with reference to the drawings.
(Schematic configuration of the image forming apparatus)
As shown in the diagram, the image forming apparatus 900 is provided with the document feeder 950 and finisher 100.
The image forming unit 930 forms toner images of a different color on the photosensitive drums 901a, 901b, 901c and 901d respectively and the toner images are transferred on the intermediate transfer belt 902. The exposure apparatus 906 projects a laser beam on the surfaces of the photosensitive drums 901a, 901b, 901c and 901d.
Firstly, a laser beam is projected from the exposure apparatus 906 on the photosensitive drums 901a, 901b, 901c and 901d, thereby electro latent images are formed on the photosensitive drums 901a, 901b, 901c and 901d. Toner is provided on the photosensitive drums 901a, 901b, 901c and 901d, thereby the electro latent images are visualized as toner images of respective colors. Subsequently, these toner images are transferred primarily on the intermediate transfer belt 902 as the photosensitive drums 901a, 901b, 901c and 901d rotate.
On the other hand, the sheets P are stored in the cassette 904. The sheets P are fed out from the cassette 904 one by one by the pickup roller 908 and conveyed to the secondary transfer position after being timed by the registration roller 909. At the secondary transfer position, toner images of four colors on the intermediate transfer belt 902 are collectively secondarily transferred on the sheet P by the secondary transfer bias applied to the secondary transfer roller pair 903.
The sheet P on which toner images of four colors are transferred is conveyed to the fixing apparatus 905 with the guidance of the conveying guide 920, where the toner images are melted so that colors are mixed by receiving heat and pressure and consequently the toner images are fixed to the sheet P. The sheet P on which a full-color image is formed is conveyed to the finisher 100 along the conveying guide 921 by the discharge roller pair 910.
(System block diagram) Next, a configuration of a controller which controls the entire image forming apparatus 900 will be described.
The controller described in
The document feed controller 204 performs drive control of the document feeder 950 based on an instruction from the CPU circuit unit 200. The image read controller 205 performs drive controls of a scanner unit, an image sensor and so on and transfers analog image signals output from the image sensor to the image signal control unit 206.
The image signal processing unit 206 converts analog image signals into digital signals and performs each processing for the digital signals thereafter. The digital signals subjected to each processing are converted into video signals which are output to the printer control unit 207. The image signal control unit 206 performs each processing for the digital image signals input via the external I/F 209 from the computer 208. The digital image signals subjected to each processing are converted into video signals which are output to the printer control unit 207. The processing by the image signal processing unit 206 is controlled by the CPU circuit 200. The printer control unit 207 performs exposure control based on the input video signals.
Operation unit 210 has plurality of keys for setting various functions relating to image formation, a display unit for displaying information indicating a setting state. The operation unit 210 outputs key signals corresponding to operations of keys respectively to the CPU circuit unit 200 and displays at the display unit the corresponding information based on signals from the CPU circuit unit 200.
The finisher control unit 220 performs drive control of the finisher 100 by exchanging information with the CPU circuit unit 200. The finisher control unit 220 controls various motors and sensors.
Next, the finisher control unit 220 which performs drive control of the finisher 100 will be described.
As shown in the diagram, the finisher control unit 220 is constituted of the CPU 221, the ROM 222, the RAM 223. The finisher control unit 220 exchanges data by communicating via the communication IC 224 with the CPU circuit unit 200 provided in the main body of the image forming apparatus 900. The finisher control unit 220 performs drive control of the finisher 100 by executing various programs stored in the ROM 222 based on an instruction from the CPU circuit unit 200.
In performing drive control of the finisher 100, detection signals from various sensors are taken into the finisher control unit 220.
The various sensors include the inlet sensor S240, the sheet surface sensor 5241, the tray lower limit sensor 5242, the paddle position sensor 5243, the assist position sensor 5244, the bundle holder position sensor 5245 and the discharge sensor 5246. The driver 225 drives the conveying motor M250, the tray lift motor M251, the paddle lift motor M252, the alignment motor M253, the assist motor M254, the staple motor M256 and the bundle holder motor M257 based on signals from the finisher control unit 220.
Operations of the above sensors and motors will be explained later in detail.
(Structure and operation of the finisher) Next, the structure and the operation of the finisher 100 will be described with reference to the
As shown in the diagram, the sheet P discharged from the main body of the image forming apparatus 900 is delivered to the inlet roller 101 and is conveyed to the conveying path of the finisher 100. The inlet roller 101 is driven by the conveying motor M250.
At this time, the delivery timing of the sheet P is controlled by detecting the front end of the sheet P by the inlet sensor 5240. The sheet P is delivered to the discharge roller 103 where the sheet P is conveyed while the front end portion of the sheet P lifts the rear end drop 105. At the same time, the sheet P is transported to the processing tray 107 (holding tray) while charge of the sheet P is removed by the charge removing needle 104. The sheet P discharged onto the processing tray 107 by the discharge roller 103 is pushed from the upper side to the lower side by the weight of the rear end drop 105 thereby the amount of the time during which the rear end portion of the sheet P falls onto the processing tray 107 is reduced. The finisher control unit 220 controls a finishing process performed in the processing tray based on a signal indicative of the rear end of the sheet P detected by the discharge sensor 5246.
As shown in the diagram, when the sheet P has fallen onto the processing tray 107, the paddle 106 moves downward to the processing tray 107 side around the rotating shaft. This downward movement is performed by rotation of the paddle lift motor M252.
The paddle 106 is rotated in the counterclockwise direction by the conveying motor M250 and the paddle 106 comes into contact with the sheet P, thereby the sheet P is conveyed to the rear end stopper 108 side in the right direction in the figure.
When the rear end of the sheet P is delivered to the knurled belt 111, the paddle 106 is moved in the upward direction by the paddle lift motor M252. When the paddle position sensor 5243 detects that the paddle 106 reaches the top position, the drive of the paddle is stopped. After the knurled belt 111 conveys the sheet P to the rear end stopper 108, the knurled belt 111 continues to convey the sheet P while slipping with respect to the sheet P, thereby a force toward the rear end stopper 108 side is always applied to the sheet P. This slip transport enables to adjust skew of the sheet P by making the sheet P abut against the rear end stopper 108.
As shown in the diagram, the sheets of the sheet bundle B abutted against the rear end stopper 108 are aligned in the width direction by the alignment plate 109 (sheet aligning portion) which is moved in the direction perpendicular to the conveying direction by the alignment motor M253. By repeating this series of operations, the sheets of the sheet bundle B is aligned on the processing tray 107.
After the predetermined number of sheets P are formed as the sheet bundle B, the staple motor M256 for driving the stapler 110 is driven when carrying out a binding process of the sheet bundle B using staples. When a binding process of the bundle B is not performed, the operation proceeds to the next process of discharging the sheet bundle without performing a binding process.
As shown in the diagram, discharge of the sheet bundle B is performed by pushing rear end of the sheet bundle B with the rear end assist 112 (moving member) and discharging projection 113 (sheet conveying member, discharging portion). Thereby, the sheet bundle B on the processing tray 107 (supporting portion) is discharged on the stacking tray 114 in a state of bundle. The rear end assist 112 and the discharging projection 113 are driven by the assist motor M254.
A detailed structure of the sheet bundle discharging unit having the rear end assist 112 and the discharging projection 113 will be explained later.
As shown in the diagram, to prevent the sheet bundle B stacked on the stacking tray 114 from being pushed out in the conveying direction by the subsequently discharged sheet bundle B, the bundle holder 115 is rotated counterclockwise by the bundle holder motor M257 for holding the rear end portion of the sheet bundle B. The position sensor 5245 detects that the bundle holder is in the predetermined retracted position and the bundle holder 115 is kept in this position when there is no need of holding the sheet bundle.
After completion of the bundle holding operation, when the sheet bundle B is shielding the sheet surface sensor 5241, the stacking tray 114 is lowered by the tray lift motor M251 until the sheet surface sensor 5241 becomes in a transmission state.
By repeating the series of operations so far, a required number of copies of the sheet bundles B can be discharged to the stacking tray 114.
When the stacking tray 114 is lowered and shields the tray lower limit sensor 5242 during operation, a signal indicating that the stacking tray 114 is full is notified to the CPU circuit unit 200 of the image forming apparatus 900 by the finisher control unit 220 and the image forming process is stopped. When the sheet bundle on the stacking tray 114 is removed, the stacking tray 114 is moved in the upward direction until the sheet surface sensor 5241 detects a light-shielding, and then the stacking tray 114 is moved in the downward direction until the sheet surface sensor S241 detects a light transmission, thereby the position of the sheet on the stacking tray 114 is determined again. After that, the image forming process of the image forming apparatus 900 is resumed.
(Structure of the sheet bundle discharging unit)
As shown in the figure, the discharging projection 113 is coupled to the discharging projection belt 502. These are arranged on the processing tray 107 two by two in the width direction orthogonal to the sheet conveying direction. The discharging projection belt 502 which is an endless belt is stretched by the pulleys 503, 504 and the cam pulley 505, which are a rotating member. Tension of the discharging projection belt 502 is added by the tensioner 506. The belt surfaces of the discharging projection belts 502 are formed along the stacking surface of the processing tray 107 between the pulleys 503 and 504.
The assist rear end 112 is coupled to the assist belt 507 through the assist slider 515 and the assist belt 507 is applied on the pulleys 508 and 509.
The assist motor pulley 552 is connected to the axis of the assist motor M254 (not shown in
In the above configuration, the assist belt 507 and the discharging projection belt 502 are driven by the assist motor M254.
The assist slider 515 which is coupled to the rear end assist 112 is slidably disposed on the slider shaft 514. The assist slider 515 has a sensor flag for detecting a position of the rear end assist 112 by turning off the assist position sensor 5244.
(Structure and operation of cam pulley) Next, a structure and an operation of the cam pulley 505 will be explained.
As shown in
Therefore, as shown in
Thereafter, as shown in
A pulley ratio is set in such a way that a moving speed of the discharging projection 113 is higher than a moving speed of the rear end assist 112, thereby, as shown in
Subsequently, the discharging projection 113 which has overtaken the rear end assist 112 pushes the sheet bundle B to the position over the pulley 503, thereby the sheet bundle B is discharged on the stacking tray 114 provided further downstream than the pulley 503 in the rotation direction of the discharging projection belt 502.
(Structure of the discharging projection) Next, the structure of the discharging projection will be explained.
As shown in the figure, distal lever 517 (pressing portion) is provided at the distal end of the downstream side of the sheet conveying direction of the discharging projection 113. Distal lever 517 is rotatable about the rotation center 517a (rotation axis) and can be moved upward when discharging the sheet bundle having many sheets. The rubber member (contact member) which has a higher coefficient of friction than that of the discharging projection 113 is attached to the lower end portion of the distal lever 517 so as to be in contact with the sheet bundle B during discharging operation. The torsion coil spring 519 (biasing member) is disposed on the center of rotation 517a of the distal lever 517, thereby a force is applied to the lower end of the distal lever 517 in the direction of coming in contact with the sheet.
By providing a rubber member 518 having a high friction coefficient in the distal end portion of the distal lever 517 in this manner, it is possible to prevent the sheet from jumping out due to the inertia force of the sheet itself when the discharging projection 113 is decelerated or stopped around the stacking tray 114. A friction coefficient of the inclination portion is lower than that of the rubber member 518.
The discharging projection 113 has the surface 113a (abutting portion) for pushing the rear end of the sheet bundle B. The distal lever 517 is attached to the discharging projection 113 via a rotating shaft which is disposed at an upper portion of the pressing surface 113 and downstream of the sheet conveying direction. The distal lever 517 is rotatable around the rotational center 517a. The distal lever 517 is configured to stop its rotation at the position where the distal lever 517 is inclined at a predetermined angle downstream of the sheet conveying direction in such a way that the lower end of the distal lever 517 approaches the pushing surface 113a. That is, the distal end of the distal lever 517, which comes in contact with the sheet, is positioned further upstream in the sheet conveying direction of the discharging projection 113 than the rotation center 517a which serves as a portion for attaching the distal lever 517 to the discharging projection 113. The distal lever 517 has an inclined surface which is inclined with respect to a holding surface of the processing tray 107. This inclined surface is configured to be inclined in such a way that as a position on the inclined surface goes further upstream in the sheet discharging direction, the position approaches more the processing tray 107.
Thus, while the discharging projection 113 pushes the sheet bundle B, the distal lever 517 presses the sheet bundle B against the conveying surface during transport. Thereby suppressing deflection of the rear ends of the sheets during the transport of the sheets and making it possible to prevent the sheets from jumping out due to the inertia force of the sheets when the discharging projection 113 is stopped or decelerated while discharging the sheets on the stacking tray 114.
As shown in the diagram, even if the rear end of the sheet bundle B1 is curled in the upper direction, the distal lever 517 is inclined with respect to the pushing surface 113a. Thus, when the sheet bundle B is delivered from the rear end assist 112 to the discharging projection 113, the sheet bundle B can be smoothly introduced to the pushing surface 113a.
Further, when the sheet bundle B is conveyed parallel to the conveying surface, a force is applied to the conveying surface of the sheet bundle B due to inclination of the distal lever 517. Meanwhile, a force toward the conveying surface is applied to the distal lever 517 by the torsion coil spring 519, but is restricted to rotate at a predetermined position by a stopper (not shown) to maintain the inclined state with respect to the pushing surface 113a. Therefore, during discharging of the sheet bundle B when the discharging projection 113 reaches the pulley 503 which stretches the discharging projection belt 502 and which is located downstream in the rotation direction of the belt, the distal end of the distal lever 517 becomes away from the sheet as shown in
(Post-processing operation) Next, an explanation will be made about post-processing operations of the post-processing performing unit of this embodiment for binding the sheet bundle B with the stapler.
When a job is started, the bundle holder 115 is moved to the bundle holding position (step ST01). Thereafter, the sheet is discharged to the processing tray 107 (step ST02). Next, the sheet is conveyed to the rear end stopper 108 by the paddle 106 and the knurled belt 111 (step ST03). Then, the sheet is aligned by the alignment plate 109 (step ST04). Next, it is determined whether the sheet P is the last of the sheet bundle B (step ST05) and if it is not the last sheet, the process returns to the step ST02.
After all the sheets P for the sheet bundle B are loaded and aligned in this way, the presence or absence of a binding process is determined (step ST06). If a stapling operation is required, it is performed (step ST07) and if it is not required, it is not performed.
Then, the sheet bundle is delivered to the discharging projection 113 from the rear end assist 112. After the rear end assist 112 moves in the predetermined amount of the movement after the sensor flag of the rear assist 112 passes through the assist position sensor 5244, the driving of the rear end assist 112 is stopped (step ST08), thereby the sheet bundle B is discharged onto the stacking tray 114. At this time, the bundle holder 115 is moved to the retracted position from the stacking tray 114 before the rear end of the sheet bundle B lands to the stacking tray 114 (step ST09). After the rear end of the sheet bundle B has landed to the stacking tray 114, the bundle holder 115 is moved to the holding position again (step ST10) in order to prepare for holding the next sheet bundle B.
Next, it is determined whether the sheet bundle B is the last bundle (step ST11). If it is not the last bundle, the process returns to the step ST02 where processing of the next sheet bundle B is performed. If it is the last bundle, the bundle holder 115 is moved to the retracted position after the last bundle is discharged (step ST12). This is for the user to easily take the sheet bundle from the stacking tray 114.
In the description described above, the configuration is adopted in which the sheet bundle B on the processing tray 107 is discharged onto the stacking tray 114 by the discharging projection 113. However, without providing the stacking tray 114, it may be configured that the sheet bundle B is moved and stopped within the processing tray 107. Even in this case, it is possible to suppress deviation of the sheet within the processing tray 107, caused by jumping of the sheet bundle B from the discharging projection 113.
Further, even if the stop position of the rotation of the distal lever 517 attached to the distal end of the discharging projection 113 is configured not to be inclined with respect to the conveying surface of the sheet bundle B in such a way that the distal lever 517 stops perpendicular to the conveying surface, the sheet bundle B can be prevented from jumping out due to the inertia force of itself.
Next, an image forming apparatus of another embodiment of the present invention will be described. For many parts of the image forming apparatus of the first embodiment are common, this embodiment describes only differences from the first embodiment. The other part is the same configuration as the first embodiment. The same reference numerals are used for the same components as the first embodiment, and redundant explanations are omitted.
According to the first embodiment, if the thickness of the sheet bundle B is large, the sheet bundle B is accepted by the movement in the retracted direction of the distal lever 517 which rotates around the predetermined rotation center of the discharging projection 113.
On the other hand, as shown in
Next, an image forming apparatus of another embodiment of the present invention will be described. For many parts of the image forming apparatus of the first embodiment are common, this embodiment describes only differences from the first embodiment. The other part is the same configuration as the first embodiment. The same reference numerals are used for the same components as the first embodiment, and redundant explanations are omitted.
As shown in the diagram, the discharging projection 113 of the present embodiment is provided with the distal lever 530 made of rubber. The distal lever 530 is configured to rotate around the rotation center 530a (rotation axis), and is movable in the upward direction when discharging the sheet bundle having many sheets. Irregularities or grooves are formed at the distal end portion 530b of the lower end of the lever 530 so that a friction coefficient of the lower end is higher than that of the rest of the distal lever 530. Further, the friction coefficient of the distal end portion 530b is higher than that of the discharging projection 113. The torsion coil spring 519 (biasing member) is disposed on the rotation center 530a of the distal lever 530 and the torsion coil spring 519 applies a force to the distal end portion 530b (contacting portion) in the direction in which the distal end portion 530b comes in contact with the sheet.
By increasing the coefficient of friction of the distal end portion 530b of the distal lever 530 in this manner, it is possible to prevent the sheet from jumping out due to the inertia force of the sheet itself when the discharging projection 113 is decelerated or stopped around the stacking tray 114.
In the present embodiment, the distal lever 530 is made of rubber but it may also be a mold member on the distal end portion (the contact portion) on which irregularities or grooves are formed for making a friction coefficient of the distal end portion higher than that of the rest of the distal lever 530.
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, equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2013-13630, filed Jun. 28, 2013, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-136300 | Jun 2013 | JP | national |
