Patent Application
20080217834
1. Field of the Invention
The present invention relates to a sheet processing apparatus to perform a post-processing on sheets discharged from an image forming apparatus such as a copier, a printer or a multi function peripheral (MFP).
2. Description of the Related Art
In recent years, among image forming apparatuses, there is one in which a sheet post-processing apparatus is provided to be adjacent to an image forming apparatus main body, so that a post-processing is performed, for example, sheets after image formation are sorted or the sheet are subjected to staple processing. Besides, there is also one in which a sheet bundle is folded in two and is discharged.
JP-A-62-16987 discloses a paper folding apparatus. In this example, there are included a pair of rollers and a folding piece, a sheet is pushed toward a nip side of the paired rollers by the folding piece, and the sheet is folded. Further, there is provided a roller to again press the folded sheet and to additionally fold it.
Besides, JP-A-2004-59304 discloses a sheet processing apparatus including paired folding rollers to fold a sheet and an additional folding roller to additionally fold the sheet. In this example, a mechanism to reduce the noise caused by the additional roller is disclosed.
Further, JP-A-2004-106991 discloses a sheet processing apparatus including paired folding rollers to fold a sheet bundle and an additional folding roller to again press the folded part of the sheet and to additionally fold it. In this example, there is provided control means for determining whether or not additional folding is performed according to the number of sheets.
Besides, JP-A-2005-162345 also discloses a sheet processing apparatus including paired folding rollers to fold a sheet bundle and an additional folding roller to again press the folded part of the sheet and to additionally fold it. In this example, there is disclosed a mechanism to uniformly press the folded part of the sheet by the additional roller.
However, in any of the above-described four examples, the structure is such that the additional folding device is added, and there have been defects that the structure is complicated, and it takes much time to perform the operation of the sheet folding.
The invention provides a sheet processing apparatus including a finisher having a sheet folding mechanism and improved in efficiency of sheet folding operation.
Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than limitations on the apparatus of the present invention.
Hereinafter, embodiments of the invention will be described in detail with reference to the drawings. Incidentally, in the respective drawings, the same portions are denoted by the same reference numerals and will be described.
The sheet processing apparatus 20 performs a post-processing on the sheet supplied from the image forming apparatus 10, and performs, for example, a sort processing or a staple processing. Besides, as the need arises, the sheet is folded in two and is discharged. Since the sheet processing apparatus 20 is generally called a finisher, in the following description, there is also a case where it is called the finisher 20.
In
A scanner unit 16 and a printer unit 17 are included in the inside of the main body 11, and a plurality of cassettes 18 containing various sizes of sheets are provided in the lower part of the main body 11. The scanner unit 16 reads a document sent by the ADF 12 or a document placed on the document table.
The printer unit 17 includes a photoconductive drum, a laser and the like, the surface of the photoconductive drum is scanned and exposed by a laser beam from the laser, and an electrostatic latent image is formed on the photoconductive drum. A charging unit, a developing unit, a transfer unit and the like are arranged around the photoconductive drum, the electrostatic latent image on the photoconductive drum is developed by the developing unit, and a toner image is formed on the photoconductive drum. The toner image is transferred to a sheet by the transfer unit. The structure of the printer 17 is not limited to the foregoing example, and there are various systems.
The finisher 20 includes a staple mechanism 21 to perform a staple processing on a sheet bundle, a saddle stitcher 30 to perform a sheet folding processing, a paper discharge tray 51 and a fixed tray 52. The paper discharge tray 51 is of a movable type, and receives a sheet bundle subjected to the staple processing. The staple mechanism 21 includes an aligning device to align the transported sheets in the width direction, and the sheets can be sorted and discharged by using this aligning device.
Incidentally, in the case where the post-processing such as stapling is not performed, the sheet transported from the image forming apparatus 10 is discharged to the paper discharge tray 51 or the fixed tray 52 without being subjected to any processing.
The structure of the finisher 20 is enlarged and shown in
The sheet stacked on the processing tray 24 is guided to a stapler 25, and a staple processing is performed. Besides, in order to transport the sheet P subjected to the sort processing or the staple processing to the paper discharge tray 51, a transport belt 26 is provided.
The sheet P transported by the transport belt 26 is discharged to the paper discharge tray 51, and the paper discharge tray 51 is moved up or down by a drive unit (not shown) and receives the sheet P.
Besides, there is also a case where the sheet P is discharged to the paper discharge tray 51 without being subjected to the staple processing. In this case, the sheet P is discharged without being dropped to the processing tray 24. Besides, the sheet P not requiring the post-processing can also be discharged to the fixed tray 52. Although a transport path to guide the sheet P to the fixed tray 52 is provided, its illustration is omitted.
Next, the structure of the saddle stitcher 30 will be described.
The saddle stitcher 30 is an apparatus to bundle sheets supplied from the image forming apparatus 10 and to fold them in two.
The sheet P transported from the image forming apparatus 10 is transported through a paper path 31 or 32, is further transported in a direction toward a stapler 34 through a paper path 33, and is once received by a stack tray 35. The sheets P transported are sequentially stacked on the stack tray 35 to form a sheet bundle, and a staple is applied to its center part.
A sheet bundle T subjected to the staple processing by the stapler 34 is moved down by a guide belt 36, and is stopped at a position where the center part of the sheet bundle T comes to a nip point of paired folding rollers 37a and 37b. A blade 38 is disposed at a position opposite to the paired folding rollers 37a and 37b.
The blade 38 protrudes the center part of the sheet bundle T to the nip point of the paired folding rollers 37a and 37b and pushes the sheet bundle T into between the folding rollers 37a and 37b. Thereafter, the paired folding rollers 37a and 37b rotate while folding and nipping the sheet bundle T, and fold the sheet bundle T in two. The sheet bundle T folded in two is transported by paired discharging rollers 39a and 39b, and is discharged to the paper discharge tray 53.
Besides, a variable speed device 40 is provided in order to rotation-drive the folding rollers 37a and 37b and the paired discharging rollers 39a and 39b. The variable speed device 40 is shown in
Incidentally, guide rollers 54, 55 and 56 are provided in order to guide the sheet P supplied from the image forming apparatus 10 along the paper paths 31, 32 and 33. Besides, a gate 57 is provided at the outlet of the guide roller 54 in order to change the transport of the sheet P supplied from the image forming apparatus 10 to the staple mechanism 21 side or the saddle stitcher 30 side.
In the case where the sheet folding processing is not performed, the gate 57 transports the sheet P discharged from the image forming apparatus 10 to the rollers 22 of the staple mechanism 21. In the case where the sheet folding processing is performed, the sheet P is transported to the saddle stitcher 30.
In
The stapler 34 applies a staple S to the center part of the sheet bundle T. Character B indicates the sheet bundle T to which the staple S is applied.
Thereafter, the sheet bundle T to which the staple S is applied is moved down by the guide belt 36. When the center part of the sheet bundle T comes to the nip point of the paired folding rollers 37a and 37b, as indicated by C, the blade 38 protrudes the center part of the sheet bundle T to the nip point of the paired folding rollers 37a and 37b, and pushes it into between the folding rollers 37a and 37b. The paired rollers 37a and 37b rotates so as to draw in the sheet bundle T, so that the sheet bundle T is folded and is discharged.
The sheet bundle T folded in two is transported by the paired discharging rollers 39a and 39b as indicated by D, and is discharged to the paper discharge tray 53.
As shown in
Besides, as shown in
Accordingly, in the case where the paired rollers 37a and 37b are rotated at a low speed, although the fold can be accurately formed, the discharge speed of the sheet bundle T becomes low. On the other hand, in the case where the paired rollers 37a and 37b are rotated at a high speed, although the discharge speed of the sheet bundle T becomes high, the function is lost due to lack of the torque, or the fold can not be accurately formed.
In the invention, at the initial stage of the folding processing, the paired folding rollers 37a and 37b are rotated at a low speed, and when the folded point of the sheet bundle T comes off from the paired folding rollers 37a and 37b, the paired folding rollers 37a and 37b are rotated at a high speed. Besides, the paired folding rollers 37a and 37b can be rotated in the low speed or high speed mode by merely changing the rotation direction of the drive motor 41.
In order to realize the rotation control as stated above, the sheet processing apparatus of the invention includes a control system of
In the block diagram of
The operation panel 13 includes the operation unit 14 having the plurality of keys and the display unit 15 used also as the touch panel, and can give various instructions for image formation. For example, the instruction of the number of copies is performed by using the operation unit 14, and the instruction of sheet size, sheet type or stapling, the instruction of sheet folding, and the like are performed by operating the touch panel of the display unit 15.
A finisher control unit 70 controls the operation of the finisher 20. The finisher control unit 70 is connected to the main control unit 60, and transmits and receives information to and from the main control unit 60, and the image forming apparatus 10 and the finisher 20 operate in cooperation with each other.
The finisher control unit 70 controls the staple mechanism 21 and the saddle stitcher 30, respectively. The control of the staple mechanism 21 includes execution of stapling by the stapler 25, transport of the sheet P to the stapler 25, discharge of the sheet after stapling, and the like.
The control of the saddle stitcher 30 includes transport of the sheet P through the paper path 33, movement and positioning of the sheet bundle T by the guide belt 36, execution of stapling by the stapler 34, and protruding of the folding blade 38. Further, a control mechanism 80 is provided for rotation control of the folding rollers 37a and 37b and the discharging rollers 39a and 39b.
The control mechanism 80 includes the variable speed mechanism 40 and a transmission mechanism 81, and the variable speed mechanism 40 includes the drive motor 41. The drive motor 41 rotates in a first direction or an opposite second direction by the control of the control unit 70. Hereinafter, the state of rotation in the first direction is called a positive rotation, and the state of rotation in the second direction is called a reverse rotation.
The drive motor 41 is a drive source for rotating the folding rollers 37a and 37b and the discharging rollers 39a and 39b. The variable speed mechanism 40 is for obtaining rotation outputs in a single direction, which are different from each other in reduction ratio, by the positive rotation and the reverse rotation of the drive motor 41. The transmission mechanism 81 is for transmitting the rotation output in the single direction to the folding rollers 37a and 37b and the discharging rollers 39a and 39b.
When the drive motor 41 makes the positive rotation, the rotation output with a low rotation speed is obtained from the variable speed mechanism 40, and when the drive motor 41 makes the reverse rotation, the rotation output with a high rotation speed is obtained from the variable speed mechanism 40. In either case, the rotation output in the same direction is obtained from the variable speed mechanism 40.
The transmission mechanism 81 is constructed of a general gear, a belt and the like, and is for rotating the folding rollers 37a and 37b and the discharging rollers 39a and 39b at a rotation speed in proportion to the rotation output in the single direction.
Accordingly, by using the rotation output in the single direction from the variable speed mechanism 40, the paired folding rollers 37a and 37b are rotated at the low speed at the initial stage of the folding processing of the sheet bundle T, and when the folded point of the sheet bundle T comes off from the paired folding rollers 37a and 37b, the paired folding rollers 37a and 37b can be rotated at the high speed.
The variable speed mechanism 40 includes the drive motor 41, a first gear 43 engaged with and rotated by a motor shaft 42 of the drive motor 41, a lever 44 rotated around a rotation shaft of the first gear 43, and a planetary gear 45 attached to the lever 44 and engaged with and rotated by the first gear 43.
Further, there are included a second gear 46 and a third gear 47 engaged with and rotated by the planetary gear 45, a fourth gear 48 engaged with and rotated by the third gear 47, and a fifth gear 49 engaged with and rotated by the second gear 46 or the fourth gear 48. The fifth gear 49 is provided integrally with a rotation shaft 50, and the rotation shaft 50 rotates in the single direction.
The lever 44 rotates in the rotation direction of the first gear 43 and is changed so that the planetary gear 45 engages with either one of the second gear 46 and the third gear 47. For example, when the first gear 43 rotates in the left direction of the drawing, the lever 44 also rotates in the left direction, and the planetary gear 45 engages with the third gear 47. When the first gear 43 rotates in the right direction, the lever 44 also rotates in the right direction, and the planetary gear 45 engages with the second gear 46.
The third and the fourth gears 47 and 48 constitute a reduction gear.
Next, the operation of the variable speed mechanism 40 will be described. When the variable speed mechanism 40 is in the state of
Thus, the rotation force of the motor 41 is transmitted to the fifth gear 49 through the first gear 46, the planetary gear 45, the third gear 47 and the fourth gear 48, and the fifth gear 49 rotates in the second direction (counterclockwise direction ccW). In the state of
On the other hand, when the motor 41 rotates in the second direction (ccw), as shown in
The rotation force of the motor 41 is transmitted to the fifth gear 49 through the first gear 46, the planetary gear 45 and the second gear 46, and the fifth gear 49 rotates in the second direction (ccW). At this time, the fifth gear 49 rotates at a high speed.
As is understood from
The rotation output of the rotation shaft 50 is transmitted to the paired folding rollers 37a and 37b and the paired discharging rollers 39a and 39b through the transmission mechanism 81. The transmission mechanism 81 includes, for example, a gear mechanism, the folding roller 37a rotates in the first direction (cw) in proportion to the rotation speed of the rotation shaft 50, and the folding roller 37b rotates in the second direction (ccW) at the same rotation speed as the folding roller 37a.
Besides, the paired discharging roller 39a rotates in the first direction (cw) at the same rotation speed as the folding roller 37a, and the discharge roller 39b rotates in the second direction (ccW) at the same rotation speed as the folding roller 37b. Accordingly, the paired folding rollers 37a and 37b and the paired discharging rollers 39a and 39b are rotated by the one drive motor 41 in conjunction with each other.
Incidentally, in
The control unit 70 controls the drive motor 41 in accordance with the transport state of the sheet bundle T, and as shown in
Besides, as shown in
Besides, since the discharging rollers 39a and 39b rotate in conjunction with the folding rollers 37a and 37b, the discharge operation of the sheet bundle T can be performed smoothly.
Alternatively, the discharging rollers 39a and 39b may be made to always rotate in the high speed mode and at the same speed as the rotation speed at the time when the folding rollers 37a and 37b rotate at the high speed.
Incidentally, the rotation direction of the drive motor 41 is controlled by the control unit 70, so that the sheet folding processing can be executed in various modes.
For example, in the case where the number of sheets of the sheet bundle T is small, even if the paired rollers 37a and 37b are not rotated at a low speed, the sheet bundle T can be relatively easily creased. Accordingly, in the case where the number of sheets to be subjected to the folding processing is smaller than a specified number, the drive motor 41 may be rotated only in the second direction, so that the sheet folding is performed at the high speed.
Methods of determining the number of sheets include a method of using information of the number of sheets inputted by the user through the operation panel 13, and a method of detecting sheets passing through the paper path 33 by a sensor and counting the number of sheets having passed.
Besides, since a noise level becomes high when the folding processing is performed at a high speed, in the case where the folding processing is desired to be executed at a low noise, the drive motor 41 is rotated only in the first direction. By this, since the folding processing is performed at a low speed, the folding processing can be performed in a low noise mode. For example, a mode switching button is provided on the operation panel 13, and the low noise mode is made selectable.
As described above, according to the invention, at the time of folding processing of a sheet, the rotation speed of the paired folding rollers is controlled, so that the efficiency of the folding processing can be improved.
Incidentally, no limitation is made by the above description, and various modifications can be made within the scope not departing from the scope of claims. For example, a first variable speed mechanism 40 may be provided for the folding roller 37a and the discharge roller 39a, and a second variable speed mechanism 40 may be provided for the folding roller 37b and the discharging roller 39b.
Although exemplary embodiments of the present invention have been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit of the present invention. All such changes, modifications, and alterations should therefore be seen as within the scope of the present invention.
