Patent Application
20100072692
The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2008-242307 filed in Japan on Sep. 22, 2008.
1. Field of the Invention
The present invention relates to a sheet processing system including a sheet processing device having a space portion as a sheet discharge unit, a sheet post-processing device removably attached into the space portion, and a sheet reversing path.
2. Description of the Related Art
A sheet post-processing such as punching, binding, and sorting performed on an image-formed sheet of paper is increasingly required of recent image forming systems. However, a sheet post-processing device that performs the sheet post-processing thereon is connected to an outer side surface of an image forming apparatus of a type that discharges the sheet from the side surface of the body of the apparatus. This configuration causes an installation space of the image forming system to be increased.
On the other hand, there are image forming apparatuses of a type that has a space portion within the installation area (inside the body of the apparatus) of the image forming apparatus and discharges a sheet of paper into the space portion, and some of the image forming apparatuses have various types of sheet post-processing devices attached into the space portion, as disclosed in Japanese Patent Application Laid-open No. 2006-206271, Japanese Patent Application Laid-open No. 2004-155566, and Japanese Patent No. 3898358.
Provided in the image forming apparatus is a plurality of sheet feeding units in order to form an image on one side or on both sides of the sheet. A switching unit is also provided therein to appropriately switch one sheet feeding unit to another for use according to a process mode.
One of the conventional image forming apparatuses is explained below. This image forming apparatus has a configuration in which various types of sheet post-processing devices can be attached into the space portion and images can be formed on both sides of the sheet.
Operations when an image is formed on one side of the sheet in the image forming apparatus in
First, the image forming unit B acquires image information from an external device or from the image reading unit C, and processes the image information. Then, as shown in
Operations when images are formed on both sides of the sheet are explained below with reference to
As shown in
Next, operations when a sheet discharge tray E is attached to an outer upper portion of the image forming apparatus and the sheet is discharged onto the sheet discharge tray E are explained with reference to
As shown in
Thus, in both-side printing, when the sheet is to be reversed upon discharge of the sheet onto the sheet discharge tray E, the reversing roller pair 6 and the sheet-discharge roller pair 13 perform the same operation, and the sheet S is received on the additional sheet-stacking tray D2, so that the sheet can be reversed. Furthermore, by setting a sheet discharge destination to the additional sheet discharge unit U, the additional sheet-stacking tray D2 can be set and used as another sheet discharge destination which is different from the sheet discharge unit D1 being an ordinary sheet discharge destination.
In the conventional technologies, if the sheet post-processing device can be attached into the space portion (in-body space) in the image forming apparatus, an image forming system including the sheet post-processing device requires only an installation area equivalent to that for a single unit of the image forming apparatus. Thus, this system can achieve significant space saving as compared with an image forming system in which the sheet post-processing device is connected to the outside of the image forming apparatus.
As explained with reference to
It is an object of the present invention to at least partially solve the problems in the conventional technology.
According to one aspect of the present invention, there is provided a sheet processing system including a sheet pre-processing device and a sheet post-processing device. The sheet pre-processing device includes a space portion as a sheet receiving unit that receives a pre-processed sheet, a first sheet conveying path for discharging the sheet to the sheet receiving unit, and a second sheet conveying path for reversing the sheet after a part of the sheet is discharged to the sheet receiving unit. The sheet post-processing device is removably attached into the space portion. The sheet processing system further includes: a conveying path for receiving the sheet from the second sheet conveying path and conveying the sheet to the sheet post-processing device when the sheet post-processing device is attached into the space portion; a reversing path for receiving the sheet from the second sheet conveying path and reversing a sheet conveying direction when the sheet post-processing device is attached into the space portion; and a switching unit that switches over the sheet conveying direction to either one of the conveying path and the reversing path.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
Exemplary embodiments of a sheet processing system according to the present invention are explained in detail below with reference to the accompanying drawings. It should be noted that in the following explanation, the same numerals are assigned to those corresponding to the components explained with reference to
In the image forming apparatus according to the embodiment, as shown in
The internal configuration of the sheet conveying path in the image forming unit B side is the same as that shown in
To attach the sheet post-processing device into the space portion D, as shown in
More specifically, as shown in
The sheet reversing unit R has two conveying paths, and a switching claw t4 switches between the conveying paths. Conveying roller pairs 11 and 12 being conveying units are provided in the conveying paths to convey the sheet. The conveying roller pair 11 is provided in one of the conveying paths that receives the sheet from the reversing roller pair 6 in the second sheet conveying path and conveys the sheet to the sheet post-processing device F. The conveying roller pair 12 functions as a reversing/conveying roller and is provided in a reversing path to receive the sheet from the reversing roller pair 6 in the second sheet conveying path and reverse the sheet.
The sheet post-processing device F includes a conveying path, a conveying unit, an aligning unit, a binding unit, and a stacking unit, so that an image-formed sheet can be post-processed.
Operations when the sheet post-processing device F is attached to perform the post-processing on the sheet are explained below.
First, operations when the sheet with an image formed on one side thereof is post-processed are explained below with reference to
As shown in
Operations when the sheet with images printed on both sides thereof is post-processed are explained below with reference to
As shown in
Further, as shown in
When the trailing edge of the sheet S1 passes through the switching claw t2, the switching claw t2 is switched and further the reversing roller pair 6 is reversed. As shown in
Next, a sheet discharge operation when the sheet discharge tray E is attached to the image forming apparatus is explained with reference to
Similarly to the case of forming images on both sides of the sheet S1, as shown in
When the trailing edge of the sheet S1 passes through the switching claw t2, the switching claw t2 is switched and further the reversing roller pair 6 is reversed. As shown in
If the sheet S1 causes a paper jam when it is reversed, as shown in
In the embodiment, when a thick or a hard sheet of paper is conveyed within a curved reversing path in the sheet reversing unit R, a conveyance resistance is made high, and the sheet is thereby difficult to be conveyed. In this case, as shown in
Moreover, a controller and control software that perform operations and controls of the sheet reversing unit R including the conveying roller pair 12 and of the sheet post-processing device F are provided in the sheet post-processing device F. Thus, minimum necessary controller and control software are only required of the image forming apparatus.
When the sheet fed from the reversing roller pair 6 in the image forming unit B is received by the conveying roller pair 12 in the reversing path, or when the sheet is between the reversing roller pair 6 and the conveying roller pair 12, the reversing roller pair 6 may be accelerated or decelerated to cause a slight difference in speed between the two roller pairs 6 and 12.
In the embodiment, therefore, as shown in
A reversing operation according to the embodiment is explained below with reference to the flowchart in
When the leading edge of the sheet to be reversed is sent to the reversing roller pair 6 in the image forming unit B (Step S1), the switching claw t4 is caused to operate so as to be on standby for guiding the sheet to the reversing path in the sheet reversing unit R. The sheet reversing unit R determines a linear velocity upon reception of the sheet based on linear velocity information sent from the image forming unit B, and rotates the conveying roller pair 12 (Step S2).
Furthermore, the sheet reversing unit R determines separation timing of the driven roller of the conveying roller pair 12 from the other by the solenoid device SOL based on size information for the sheet sent from the image forming unit B (Step S3). In the image forming apparatus, when the sheet is in a fixing unit (not shown) that fixes the formed image on the sheet, the sheet is conveyed at a regular linear velocity for image forming process, however, when the sheet passes through the fixing unit, the linear velocity is accelerated to a linear velocity for sheet discharge.
At this time, synchronization between operations is difficult because the components are differently driven, and thus, in the embodiment, the separation operation is implemented under the following three conditions (Step S4).
(1) If the size of the sheet is such that the sheet reaches the conveying roller pair 12 before the acceleration is started, then the sheet is received at the linear velocity for image forming process, and the driven roller of the conveying roller pair 12 is separated from the other at a distance of χ millimeters in front of an acceleration starting point of the sheet. After the separation, the sheet is conveyed by the reversing roller pair 6.
(2) If the size of the sheet is such that the sheet reaches the conveying roller pair 12 after the acceleration is completed, then the sheet is received at the linear velocity for sheet discharge, and the driven roller of the conveying roller pair 12 is separated from the other at a distance of χ millimeters in front of a sheet stopping point.
(3) If the size of the sheet is such that the sheet reaches the conveying roller pair 12 during the acceleration, then, before the sheet is received by the conveying roller pair 12, the driven roller of the conveying roller pair 12 is separated from the other. After the separation, the sheet is conveyed by the reversing roller pair 6.
When the sheet starts to be switched back, the driven roller of the conveying roller pair 12 is separated from the other by the solenoid device SOL, and at this state, the sheet is again conveyed to the image forming unit B only by the reversing roller pair 6.
In the embodiment, the control system and control software are configured so that respective drive systems of the sheet reversing unit R and the sheet post-processing device F can be mutually, simultaneously controlled, which enables the sheet reversing unit R to receive a subsequent sheet to be reversed and reverse the subsequent sheet even in the middle of performing the post processing on a preceding sheet in the sheet post-processing device F. Thus, the sheet can be post-processed without decrease in entire productivity of the image forming and sheet processing system.
Moreover, even if the paper jam occurs inside the sheet post-processing device F and conveyance of the sheet is stopped therein, the sheet reversing unit R receives the sheet discharged from the reversing roller pair 6 in the image forming unit B and reverses the sheet, and then switches back the sheet to be conveyed from the right-side conveying path in the image forming unit B to the sheet discharge tray E. Thus, the sheet can be discharged without disturbing the printing order and stacked thereon. Besides, even if the sheet post-processing device F is stopped due to some malfunction, the sheet can be conveyed to the sheet discharge tray E, and thus system down can be prevented.
Because regular jobs related to image control are executed in the image forming apparatus, even if the sheet is continuously stopped during the reversing operation within the reversing path in the sheet reversing unit R when printing and conveying of the sheet are temporarily stopped, the system has to be designed so as not to determine the stoppage as a paper jam according to the control system. Thus, even if the sheet is stopped in the sheet reversing unit R, the control can be performed in the image forming apparatus and can also performed with a specified number of sheets, which is useful in maintenance and improvement of image quality. Therefore, when the image control is finished and printing and conveying of the sheet are restarted in the image forming apparatus, then the reversing operation of the sheet is restarted.
However, when a stop instruction is output in a state in which the sheet is stopped during the reversing operation, any malfunction may occur in the sheet processing system. Therefore, the processes at normal times are caused to interrupt, and “remaining-sheet check process” and “remaining-sheet detection process” are performed as processes upon malfunction. For example, it is detected whether any sheet remains within the sheet conveying path, and if the sheet is detected, then a massage indicating that the sheet remains is displayed or a message prompting the user to remove the sheet is displayed.
According to one aspect of the present invention, a sheet reversing path is installed in the space portion in the sheet pre-processing device, which prevents the entire system from being increased in size even if the sheet post-processing device is installed in the space portion, and even the sheet long in the conveying direction can be reversed without letting it out of the device. Thus, even if a paper jam occurs inside the reversing path, the paper jam can be easily fixed.
Furthermore, according to another aspect of the present invention, the space between the sheet post-processing device and the sheet pre-processing device is used as a guide of the reversing path, which allows space saving and reduction in the number of components.
Moreover, according to still another aspect of the present invention, the partition member can prevent dropping of the sheet or of any foreign matter from the space portion.
Furthermore, according to still another aspect of the present invention, the partition member can be used as a work table upon placement of the sheet post-processing device.
Moreover, according to still another aspect of the present invention, the sheet can be discharged onto the sheet tray other than the space portion, so that convenience for users is increased.
Furthermore, according to still another aspect of the present invention, it is possible to select a state of the sheet when it is discharged and a discharge position of the sheet.
Moreover, according to still another aspect of the present invention, the reversing/conveying roller supports the conveyance of the sheet, so that a stable reversing operation is performed.
Furthermore, according to still another aspect of the present invention, there is no need to provide the controller required for operation control of the sheet post-processing device and the reversing path in the side of the sheet pre-processing device.
Moreover, according to still another aspect of the present invention, the operation timing with the other components or the operation timing between the rollers, and a dimension error or the like can be appropriately controlled.
Furthermore, according to still another aspect of the present invention, an acceleration/deceleration control for driving the rollers upon delivery of the sheet is stabilized, so that excellent conveyance is performed without any damage given to the sheet.
Moreover, according to still another aspect of the present invention, a preceding sheet and a subsequent sheet can be simultaneously processed, which prevents degradation in productivity.
Furthermore, according to still another aspect of the present invention, even if the malfunction occurs during the post-processing for the sheet, an operation such as sheet conveyance other than the post-processing for the sheet can be executed.
Moreover, according to still another aspect of the present invention, even if the sheet is stopped in the reversing path due to some processes in the pre-processing, this stoppage is not determined as a paper jam. Thus, it is possible to prevent any unnecessary operation such as a request for removal of the sheet.
Furthermore, according to still another aspect of the present invention, a punching process becomes possible without being performed by the sheet post-processing device.
Moreover, according to still another aspect of the present invention, even if the sheet post-processing device or the like can be removably attached into the space portion of the sheet pre-processing device, by installing the reversing path of the sheet in the space portion of the sheet pre-processing device, the entire system can be prevented from being increased in size, and even a sheet long in the conveying direction can be reversed without letting it out of the image forming apparatus. Thus, the practical effect is so significant that the paper jam can be easily fixed even if it occurs within the reversing path.
Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-242307 | Sep 2008 | JP | national |
