The present application claims priority to and incorporates by reference the entire contents of Japanese priority document 2007-218634 filed in Japan on Aug. 24, 2007.
1. Field of the Invention
The present invention relates to a technology for controlling driving of transport rollers in a paper transport device for use in a paper processing apparatus.
2. Description of the Related Art
In a paper post-processing apparatus used with an image forming apparatus, when abnormal events such as paper-jamming, cover's opening during paper transport, or mechanical abnormality occur, paper cannot be transported in a desired manner. Therefore, when such events occur, entire driving of the paper post-processing apparatus is forced to stop. When a paper that has being transported is remained in the paper post-processing apparatus at the time of stopping of the driving, a paper removal process is firstly performed and then a recovery process is performed on a remained paper so that the remained paper is subjected again to image forming processing, post-paper processing, and paper ejecting processing.
However, when the leading edge of a paper is present downstream of a paper ejecting roller at the time of stopping of the paper post-processing apparatus, the paper may be ejected outside of the apparatus due to delay in stopping of the paper ejecting roller even when the apparatus commands to keep the paper inside of the apparatus. Alternatively, a user may pull out the paper when the leading edge of the paper is ejected outside of the paper post-processing apparatus, and may consider the paper as acceptable. In this case, because the paper-post processing apparatus considers that the paper is still remained in the apparatus although the paper is actually ejected, the recovery process including image forming processing and paper processing is re-performed, resulting in redundant output.
For example, Japanese Patent Application Laid-open No. H09-71363 discloses a sheet post-processing apparatus that can cope with the above situation. Specifically, the sheet post-processing apparatus includes a plurality of sheet processing units each of which can be driven independently to execute a sequential process along a flow of transporting a sheet. With this configuration, it is possible to eliminate a remained sheet removal process resulting from stopping of the apparatus and to prevent interruption of sheet processing. More specifically, the sheet post-processing apparatus includes a stopping unit that, when abnormality is detected in any one of the sheet processing units, stops the sheet processing unit with the abnormality; a selecting unit that selects another sheet processing unit to be stopped simultaneously with the sheet processing unit with the abnormality based on a position of the sheet processing unit with the abnormality; and a simultaneous stopping unit that stops the selected sheet processing unit.
Furthermore, another sheet post-processing apparatus is disclosed in Japanese Patent Application Laid-open No. H08-231121. The sheet post-processing apparatus is configured such that even if paper-jamming occurs in a post-processing apparatus, sheet (paper) transport in an image forming apparatus need not be stopped immediately and a sheet removal process can be carried out easily. Specifically, the sheet post-processing apparatus receives a paper ejected out from a paper ejecting unit of an image forming apparatus and transports the received paper through a single transport path to a sorting unit, where the paper is sorted out and is transported for sheet alignment. This sheet post-processing apparatus includes an entrance guide plate disposed at an entrance end of the single transport path facing the paper ejecting unit of the image forming apparatus, and a releasing unit that releases the entrance guide plate when paper-jamming occurs in the sheet post-processing apparatus.
However, if a paper at the upstream side is stopped while a paper at the downstream side is being transported, such a trouble as folding, tearing, and roller abrasion (soil) of the paper at the downstream side may occur on the paper at the downstream side, especially when the distance between both papers is short. For example, when the trailing edge of the downstream paper has not passed a stopped roller after an upstream processing unit is stopped or when the downstream paper comes in contact with the upstream paper and causes a paper-jamming, the downstream paper is damaged by folding, breaking, roller abrasion (soil), or the like.
It is an object of the present invention to at least partially solve the problems in the conventional technology.
According to an aspect of the present invention, there is provided a paper transport device that includes a plurality of transport rollers that transport one or more papers at a time, the transport rollers includes an ejecting roller disposed at a position from which a paper is ejected outside of the paper transport device, the ejecting roller capable of running independent of other transport rollers; a paper-jamming detecting unit that detects paper-jamming of a paper that is being transported by the transport rollers; a position detecting unit that detects positions of papers that are being transported by the transport rollers; and a control unit that controls driving of the transport rollers, wherein when the paper-jamming detecting unit detects paper-jamming and the position detecting unit detects either that no paper is present downstream of a jammed paper, or that a preceding paper that is present most downstream is located upstream of a predetermined position, the control unit stops the transport rollers to prevent ejection of papers outside of the paper transport device, and when the paper-jamming detecting unit detects paper-jamming and the position detecting unit detects that a preceding paper that is present most downstream is located downstream of the predetermined position, the control unit drives the ejecting roller to complete ejection of the preceding paper.
According to another aspect of the present invention, there is provided a paper transport device that includes a plurality of transport rollers that transport one or more papers at a time, the transport rollers includes an ejecting roller disposed at a position from which a paper is ejected outside of the paper transport device, the ejecting roller capable of being driven independent of other transport rollers; an abnormality detecting unit that detects abnormality of each of mechanisms of the paper transfer device; a position detecting unit that detects positions of papers that are being transported by the transport rollers; and a control unit that controls driving of the transport rollers, wherein when the abnormality detecting unit detects abnormality of at least one of the mechanisms and the position detecting unit detects either that no paper is present downstream of a mechanism with the abnormality, or that a preceding paper that is present most downstream is located upstream of a predetermined position, the control unit stops the transport rollers to prevent ejection of papers outside of the paper transport device, and when the abnormality detecting unit detects abnormality of at least one of the mechanisms and the position detecting unit detects that a preceding paper that is present most downstream is located downstream of the predetermined position, the control unit drives the ejecting roller to complete ejection of the preceding paper.
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 the present invention are described in detail below with reference to the accompanying drawings.
In the following embodiments, a plurality of transport rollers correspond to an entrance roller 1, transport rollers 2 and 5, and a shift paper ejecting roller 6 (composed of a driving roller 6a and a driven roller 6b), (hereinafter, “paper ejecting roller 6”); an ejecting roller corresponds to the paper ejecting roller 6; a paper-jamming detecting unit corresponds to a CPU 360 and sensors 301, 302, 303, 304, 305, 306, 321, and 323 (although collectively referred to as “sensors”, each of which is named uniquely as will be described below) that are disposed on transport paths; a position detecting unit corresponds to the sensors 301, 302, 303, 304, 305, 306, 310, 321, and 323 that are disposed on transport paths; a control unit corresponds to the CPU 360; a cover opening/closing detecting unit corresponds to a front cover opening/closing sensor 340; an abnormality detecting unit corresponds to the CPU 360; a first detecting unit corresponds to the shift paper ejecting sensor 303; a second detecting unit corresponds to the paper trailing edge detecting sensor 306; a paper processing apparatus corresponds to a paper post-processing apparatus PD; and an image forming apparatus corresponds to an image forming apparatus PR.
1. General Configuration
The paper post-processing apparatus PD is attached to a side of the image forming apparatus PR, and a paper ejected out of the image forming apparatus PR is guided to the paper post-processing apparatus PD. The paper is distributed by branch nails 15 and 16 to a transport path A having a post-processing unit (a punching unit 100 serving as a holing unit in this embodiment) that carries out a post-process on a single paper, to a transport path B that guides the paper through the transport path A to an upper tray 201, to a transport path C that guides the paper to a shift tray 202, and to a transport path D that guides the paper to a processing tray F (hereinafter, “end face stitching process tray”) that carries out paper aligning, stapling, etc.
The image forming apparatus PR at least includes the following components although drawings depicting the components are not provided: an image processing circuit that converts input data into printable image data; an optical writing device that optically writes in data on a photosensitive element based on an image signal output from the image processing circuit; a developing device that develops by toner a latent image formed on the photosensitive element by optical writing; a transfer device that transfers a toner image developed by the developing device to a paper; and a fixing device that fixes the toner image transferred onto the paper. The paper bearing a fixed toner image is sent to the paper post-processing apparatus PD, which carries out a desired post-process. The image forming apparatus PR is assumed as an electrophotographic type as described above, but can be any known image forming apparatuses employing an ink-jet method, thermal transport method, etc. In this embodiment, the image forming circuit, the optical writing device, the developing device, the transfer device, and the fixing device forms an image forming unit.
A paper is guided through the transport paths A and D to the end face stitching process tray F, where the paper is subjected to processing such as paper aligning or stapling. The paper is then distributed by a guide member 44 to the transport path C leading to the shift tray 202, and to a saddle stitching/center folding process tray G (hereinafter, “saddle stitching process tray”). The paper subjected to a folding process, etc. at the saddle stitching process tray G is guided through a transport path H to a lower tray 203. A branch nail 17 is disposed in the transport path D, where the branch nail 17 is kept in a state shown
The transport path A is shared by the transport paths B, C, and D at the upstream side thereof and provided with the entrance sensor 301 that detects a paper coming in from the image forming apparatus PR, the entrance roller 1, the punching unit 100, a punching residue hopper 101, the transport roller 2, and the branch nails 15 and 16, which are disposed in that order along the transport path A from the upstream side to the downstream side. The branch nails 15 and 16 are kept in a state shown in
When a paper is guided to the transport path B, the solenoid is turned OFF in the state of
The paper post-processing apparatus PD is capable of performing the following processes on papers: punching by the punching unit 100; jogging and end stitching by a jogger fence 53 and an end face stitching stapler S1; jogging and saddle stitching by a saddle stitching upper jogger fence 250a, a saddle stitching lower jogger fence 250b, and a saddle stitching stapler S2; sorting by the shift tray 202; and center folding by a folding plate 74 and a folding roller 81.
2. Shift Tray Unit
As shown in
The return roller 13 is a sponge roller that comes in contact with a paper ejected out of the paper ejecting roller 6 to butt the trailing edge of the paper against an end fence 32 to align the paper. The return roller 13 is rotated by the torque of the paper ejecting roller 6. A tray lift limiting switch 333 is disposed near the return roller 13. When the shift tray 202 moves up to push up the return roller 13, the tray lift limiting switch 333 is turned ON to stop a tray lifting motor 168. This prevents the overrun of the shift tray 202. Near the return roller 13, as shown in
In the present embodiment, a paper-surface detecting sensor 330a (for stapling) and a paper-surface detecting sensor 330b (for non-stapling) are turned ON when shielded by a shielding unit 30b. When the shift tray 202 moves up to turn a contact portion 30a of a paper-surface lever 30 upward, the paper-surface detecting sensor 330a is turned OFF first. Then, when the paper-surface lever 30 is further turned upward, the paper-surface detecting sensor 330b is turned ON. When the paper-surface detecting sensor 330a and the paper-surface detecting sensor 330b detect the height of a stack of papers reaches a predetermined height, the tray lifting motor 168 starts to lower the shift tray 202 by a predetermined distance. This keeps the paper-surface position of the shift tray 202 substantially constant.
As shown in
A driving source that moves up and down the shift tray 202 is the tray lifting motor 168 capable of rotating clockwise and counterclockwise. Motive power generated by the tray lifting motor 168 is transmitted to a final gear of a gear train (not shown) fixed to the driving shaft 21 via a worm gear 25. The worm gear 25 interposed in the gear train enables holding the shift tray 202 at a constant position, which prevents an unexpected accident, such as drop of the shift tray 202.
A shielding plate 24a is formed integrally on the side plate 24 of the shift tray 202, and a full load detecting sensor 334 that detects a full load of a stacked papers and a lower limit sensor 335 that detects a lower limit position of the shift tray 202 are disposed below the shielding plate 24a. The shielding plate 24a turns ON and OFF the full load detecting sensor 334 and the lower limit sensor 335. The full load detecting sensor 334 and the lower limit sensor 335 are photosensors and turned ON when shielded by the shielding plate 24a. The paper ejecting roller 6 is not shown in
A moving mechanism of the shift tray 202 is shown in
The paper ejecting roller 6 includes the driving roller 6a and the driven roller 6b. As shown in
3. End Face Stitching Process Tray Unit
A configuration of the end face stitching process tray F that carries out the stapling process is shown in
3.1 General Configuration of End Face Stitching Process Tray
Papers guided by the staple paper ejecting roller 11 to the end face stitching process tray F are stacked sequentially on the end face stitching process tray F. In this case, each paper is aligned vertically (paper transport direction) by the return roller 12, and is aligned horizontally (direction perpendicular to the paper transport direction, which is called “paper width direction”) by the jogger fence 53. At a break in a series of jobs, that is, at a break between the last paper of a paper sheaf and the head paper of the next paper sheaf, the end face stitching staple S1 is driven by a staple signal from a control circuit 350 (see
3.2 Paper Releasing Mechanism
As shown in
The releasing belt 52 is arranged at the alignment center in the paper width direction, and is stretched between a driving pulley 52d and a driving pulley 52e, as shown in
3.3 Processing Mechanism
As shown in
As shown in
3.4 Paper Sheaf Trailing Edge Pressing Mechanism
A mechanism that presses a bulge on the trailing edge of a paper sheaf placed on the end face stitching process tray F is shown in
Each of papers ejected onto the end face stitching process tray F is aligned vertically (paper transport direction) by the return roller 12, as described above. If the trailing edge of a stack of papers placed on the end face stitching process tray F is curled or easy to buckle, the trailing edge is likely to yield to the weight of the papers, resulting in buckle and bulge. As the number of stacked papers increases, a gap for receiving the next paper in the trailing edge fence 51 gets smaller, leading to inferior vertical alignment. The trailing edge pressing mechanism reduces a bulge on the trailing edge of a paper sheaf to make it easy for a paper to come into the trailing edge fence 51.
As shown in
A positional relation between each of the trailing edge pressing levers 110a, 110b, and 110c and the end face stitching stapler S1 in each stitching mode is different from one another. The stand-by position of the stapler S1 in a front side stitching mode is shown in
4. Paper Sheaf Turning Mechanism
As shown in
In the transport mechanism 35, a driven roller 42 is disposed opposite to the roller 36. A paper sheaf is sandwiched between the driven roller 42 and the roller 36, and is pressurized by an elastic material 43 to give the paper sheaf a transport force. The thicker the paper sheaf P becomes, the greater the transport force, that is, pressurization force, must be. For this reason, a configuration shown in
The turn transport path 57, which is the transport path for transporting the paper sheaf from the end face stitching process tray F to the saddle stitching process tray G, is formed of the releasing roller 56 and the guide member 44 opposite to the releasing roller 56. The guide member 44 rotates about a fulcrum 45, and is driven by a driving force transmitted from a sheaf branch driving motor 161. A home position of the guide member 44 is detected by a sensor SN2. As shown in
As shown in
As shown in
As shown in
As shown in
In the present embodiment, the releasing roller 56 functions as a driven roller that is not restricted by the driving shaft driving the releasing belt 52 but is configured to follows the transport motion of the paper sheaf. However, the releasing roller 56 can function as a driving roller driven by the releasing motor 157. When the releasing roller 56 functions as the driving roller, a circumferential speed of the releasing roller 56 is set to be higher than a circumferential speed of the releasing belt 52.
5. Saddle Stitching Process Tray
Saddle stitching and center folding is carried out at the saddle stitching process tray G disposed at the downstream side of the end face stitching process tray F. A paper sheaf is guided by the paper sheaf turning mechanism from the end face stitching process tray F to the saddle stitching process tray G. A configuration of the saddle stitching process tray G is described below.
5.1 Configuration of Folding Process Tray
As shown in
A movable trailing edge fence 73 is disposed across the lower sheaf transport guide plate 91, and can be moved in the paper transport direction (vertical direction in
The center folding mechanism is disposed substantially at the center of the saddle stitching process tray G, and is composed of the folding plate 74, the folding roller 81, and a transport path H through which the folded paper sheaf is transported.
5.2 Folding Plate and Operating Mechanism Thereof
The folding plate 74 has long holes 74a in which two shafts erected on a front side plate and a rear side plate are fitted loosely, respectively, to support the folding plate 74 such that the folding plate 74 is movable longitudinally along the long holes 74a. A shaft 74b of the folding plate 74 is fitted in a long hole 76b of a link arm 76. As a result, the folding plate 74 reciprocates left and right in
In this embodiment, it is assumed that center folding is carried out when a sheaf of papers are stitched. The present invention, however, applies also to a case of folding of a single paper. Because saddle stitching is unnecessary when a single paper is processed, the single paper is sent immediately into the saddle stitching process tray G at the point that the paper is ejected. The paper is then subjected to a folding process by the folding plate 74 and the folding roller 81, and is ejected from a lower paper ejecting roller 83 onto the lower tray 203. Reference numeral 323 denotes a folding unit passage sensor that detects an inwardly folded paper, reference numeral 321 denotes a sheaf detecting sensor that detects the paper sheaf's reaching an center folding position, and reference numeral 322 denotes a movable trailing edge fence home position sensor that detects the home position of the movable trailing edge fence 73.
In this embodiment, the lower tray 203 is provided with a detecting lever 501 swingable about a fulcrum 501a. The detecting lever 501 detects the stack height of a sheaf of inwardly folded papers. The angle of the detecting lever 501 is detected by a paper-surface sensor 505 to detect the ascending/descending motion and overflow of the lower tray 203.
5.3 Modes and Ejection Patterns
In the present embodiment, the following post-processing modes are set, and a paper is ejected according to each of the modes. The post-processing modes include the following five types.
Nonstaple mode (A): a mode in which a paper is transported through the transport paths A and B, and is ejected onto the upper tray 201.
Nonstaple mode (B): a mode in which a paper is transported through the transport paths A and C, and is ejected onto the shift tray 202.
Sort/stack mode: a mode in which a paper is transported through the transport paths A and C, and is ejected onto the shift tray 202, which swings in the direction perpendicular to the paper ejecting direction at each end of a lot to sort out ejected papers.
Staple mode: a mode in which a paper sheaf is transported through the transport paths A and D to the end face stitching process tray F, where the paper sheaf is aligned and stitched, and then is transported through the transport path C to be ejected onto the shift tray 202.
Saddle stitching bookbinding mode: a mode in which a paper sheaf is transported through the transport paths A and D to the end face stitching process tray F, where the paper sheaf is aligned and stitched at its center, and is sent to the process tray G where the paper sheaf is folded at its center, and then is transported through the transport path H to be ejected onto the lower tray 203.
Operation carried out in each mode is described below.
(1) Operation in Nonstaple Mode (A)
A paper distributed by the branch nail 15 on the transport path A is guided to the transport path B, from which the paper is ejected onto the upper tray 201 by the transport roller 3 and the upper paper ejecting roller 4. The upper paper ejecting sensor 302 disposed near the upper paper ejecting roller 4 for detection of paper ejection monitors the state of paper ejection.
(2) Operation in Nonstaple Mode (B)
A paper distributed by the branch nails 15 and 16 on the transport path A is guided to the transport path C, from which the paper is ejected onto the shift tray 202 by the transport roller 5 and the paper ejecting roller 6. The shift paper ejecting sensor 303 disposed near the paper ejecting roller 6 for detection of paper ejection monitors the state of paper ejection.
(3) Operation in Sort/Stack Mode
In this mode, a paper is transported and ejected in the same manner as in the nonstaple mode (B). When the paper is ejected, the shift tray 202 swings in the direction perpendicular to the paper ejecting direction at each end of a lot to sort out ejected papers.
(4) Operation in Staple Mode
A paper distributed by the branch nails 15 and 16 on the transport path A is guided to the transport path D, from which the paper is ejected onto the end face stitching process tray F by the transport rollers 7, 9, and 10 and the staple paper ejecting roller 11. At the end face stitching process tray F, papers that have been sequentially ejected out of the staple paper ejecting roller 11 are aligned. When a predetermined number of papers are stacked into a paper sheaf, the paper sheaf is subjected to the stitching process by the end face stitching stapler S1. The stitched paper sheaf is then transported downstream by the releasing nail 52a, and is ejected onto the shift tray 202 by the paper ejecting roller 6. The shift paper ejecting sensor 303 is disposed near the paper ejecting roller 6 for detection of paper ejection. The shift paper ejecting sensor 303 monitors the state of paper ejection.
(4-1) Releasing Process after Stapling
When the staple mode is selected, the jogger fence 53 moves from the home position to a stand-by position where each side of the jogger fence 53 is 7 millimeters distant from each edge of the width of a paper ejected onto the end face stitching tray F, as shown in
When a given time has passed after turning OFF of the striking SOL 170, the jogger fence 53 is moved further inward by 2.6 millimeters by the jogger motor 158 to halt to end lateral jogging. The jogger fence 53 then moves outward by 7.6 millimeters to return to the stand-by position, and waits for a next paper. This operation is repeated until the paper of the last page is processed. Subsequently, the jogger fence 53 moves inward by 7.6 millimeters again to stop, and holds both side ends of a paper sheaf to be ready for stapling. After a given time has passed, the end face stitching stapler S1 is actuated by a staple motor (not shown) to carry out the stitching process. If stitching at two or more spots is specified, the stapler moving motor 159 is driven after the end of stitching at one spot to move the end face stitching stapler S1 along the trailing edge of the paper to a proper spot, where stitching at the second spot is carried out. When a third spot or additional spot for stitching is specified, this operation is repeated.
When the stitching process is over, the releasing motor 157 is driven to drive the releasing belt 52. At the same time, the paper ejecting motor is also driven, which causes the paper ejecting roller 6 to start rotating to receive the paper sheaf lifted by the releasing nail 52a. At this time, the jogger fence 53 is controlled in different manners depending on sizes of papers and the number of stitched papers. For example, when the number of stitched papers is smaller than a preset number of papers or the size of papers is smaller than a preset size, the releasing nail 52a hooks on the trailing edge of the paper sheaf to transport the paper sheaf while the jogger fence 53 keeps holding the paper sheaf. After a given number of pulses are generated through detection of the paper sheaf by the paper presence/absence sensor 310 or the releasing belt HP sensor 311, the jogger fence 53 is retracted by 2 millimeters to release the paper sheaf from the jogger fence 53. A predetermined number of pulses are set within a period from the point of the releasing nail's contacting the trailing edge of the paper sheaf to the point of the trailing edge's passing the leading edge of the jogger fence 53. When the number of stitched papers is greater than the preset number of papers or the size of papers is larger than the preset size, the jogger fence 53 is retracted by 2 millimeters in advance, and the paper sheaf is released. In both cases of the number of stitched papers and size of papers, when the paper sheaf passes through the jogger fence 53, the jogger fence 53 moves further outward by 5 millimeters to return to the stand-by position reading preparation for a next paper. The restraint of the papers by the jogger fence 53 can be adjusted by adjusting the distance from the jogger fence 53 to the papers.
(5) Operation in Saddle Stitching Bookbinding Mode
Referring to
As shown in
The paper sheaf is transported from the position shown in
The position of the paper sheaf shown in
As shown in
As shown in
6. Control Circuit
The control operation to be described below is executed by the CPU 360. The CPU 360 reads program codes stored in a ROM (not shown), loads the read program codes onto a RAM (not shown), and executes the control operation based on computer programs indicated by the program codes, using the RAM as a work area.
7. Operation
7.1 Stopping Operation at the Time of Paper-Jamming
A stopping operation at the time of paper-jamming is carried out as one of the control operation. In this control operation, upon detection of paper-jamming, when another paper is not present downstream of a paper causing the paper-jamming, or even if such another paper is present, when the most downstream side paper is located upstream of a specified position, transport rollers are stopped to prevent ejection of all papers on transport out of the post-processing apparatus. Furthermore, upon detection of paper-jamming, when another paper is present downstream of a paper causing the paper-jamming and the most downstream side paper is located downstream of the specified position, an ejecting roller is kept driven to completely eject only the most downstream side paper. In this process, at the occurrence of the cause of stopping operation, when the leading edge of the most downstream side paper is located upstream of the paper ejecting roller (i.e., the leading edge of the paper is in the post-processing apparatus), transport rollers are stopped to prevent ejection of all papers on transport out of the post-processing apparatus. When the leading edge of the paper is located downstream of the paper ejecting roller (i.e., the leading edge of the paper is out of the post-processing apparatus), only the paper whose leading edge is located downstream of the paper ejecting roller is completely ejected out.
The CPU 360 makes a determination on paper-jamming detection based on the passage time of the paper and a timing of detection of the leading edge or trailing edge of a paper by a plurality of paper detecting sensors arranged along a transport path. For example, as shown in
In a case where paper-jamming (paper-jamming caused by a stalled paper in
On the contrary, when a paper being transported by the transport rollers is present downstream of the paper-jamming causing paper 401 (Step S102 and Yes at Step S103) and the most downstream side paper 402 is located downstream of the specified position (Yes at Step S103), for example, when the leading edge of the most downstream side paper 402 is located downstream of the paper ejecting roller 6 (Yes at Step S113), only the most downstream side paper 402 is kept ejected while other papers are stopped.
7.2 Stopping Operation at the Time of Cover's Opening
A stopping operation at the time of the cover's opening is carried out as one of the control operation. In this control operation, upon detection of the cover's opening, when the most downstream side paper is at the upstream side of the specified position, transport rollers are stopped to prevent ejection of all papers out of the post-processing apparatus. Furthermore, upon detection of the cover's opening, when the most downstream side paper is at the downstream side of the specified position, the paper ejecting roller is kept driven to completely eject only the most downstream side paper. In this process, at the occurrence of the cause of stopping operation, when the leading edge of the most downstream side paper is located upstream of the paper ejecting roller (i.e., the leading edge of the paper is in the post-processing apparatus), transport rollers are stopped to prevent ejection of all papers out of the post-processing apparatus. Furthermore, when the leading edge of the paper is located downstream of the paper ejecting roller (i.e., the leading edge of the paper is out of the post-processing apparatus), only the paper whose leading edge is downstream of the paper ejecting roller is completely ejected out.
The paper post-processing apparatus PD has a front cover (not shown) on an enclosure, which can be opened and closed for handling paper-jamming or replacing a staple unit. A specific process needs to be taken when the front cover is opened during transport of papers, which is described below. A state of open or close of the front cover is detected by the front cover opening/closing sensor 340. When the front cover opening/closing sensor 340 detects the cover's opening during transport of papers (Steps S121 and Yes at Step S131) and the most downstream side paper 402 is present upstream of the specified position (No at Step S122), for example, the leading edge of the most downstream side paper 402 is located upstream of the paper ejecting roller 6 (No at Step S132), all papers are stopped, as shown in
7.3 Stopping Operation at the Time of Occurrence of Abnormality
A stopping operation at the time of occurrence of an abnormality is carried out as one of the control operation. In this control operation, upon detection of an abnormality, e.g., an operation failure of any one of mechanisms in the paper post-processing apparatus PD, when another paper is not present downstream of a mechanism with the abnormality, or even if such a paper is present, when the most downstream side paper is present upstream of the specified position, transport rollers are stopped to prevent ejection of all papers out of the post-processing apparatus. Furthermore, upon detection of an abnormality of at least one of the mechanisms, when another paper is present downstream of a mechanism with the abnormality and the most downstream side paper is present downstream of the specified position, an ejection roller is kept driven to completely eject only the most downstream side paper. In this process, at the occurrence of the cause of stopping operation, when the leading edge of the most downstream side paper is located upstream of the paper ejecting roller (i.e., the leading edge of the paper is in the post-processing apparatus), transport rollers are stopped to prevent ejection of all papers out of the post-processing apparatus. When the leading edge of the paper is located downstream of the paper ejecting roller (i.e., the leading edge of the paper is out of the post-processing apparatus), only the paper whose leading edge is located downstream of the paper ejecting roller is completely ejected out. In detecting abnormality, for example, the CPU 360 determines an occurrence of an abnormality when the CPU 360 executes prescribed control over each unit and an operation following the control by the CPU 360 is not completed even after a scheduled time passes. The scheduled time is at which execution of the control is supposed to be completed.
The paper post-processing apparatus PD is capable of separately detecting various mechanical abnormalities, such as jamming and operation failure. For example, in a case where an abnormality of a mechanism is detected on the punching unit 100 (Step S141 and Yes at Step S151), when a paper being transported by the transport rollers is not present downstream of the mechanism (Step S142 and No at Step S152) or, even if such a paper is present, when the most downstream side paper 402 is present upstream of the specified position (No at Step S143), for example, the leading edge of the most downstream side paper 402 is located upstream of the paper ejecting roller 6 (No at Step S153), all papers are stopped, as shown in
In the cases described in 7.1, 7.2, and 7.3, the paper ejecting roller 6 has a driving motor (shift paper ejecting motor (not shown)) independent of other transport rollers. This allows a choice on whether the paper ejecting roller 6 is to be kept operated independently after the stoppage of other transport rollers or stopped simultaneously with the stoppages of other transport rollers.
Each operation described above attains the following effects. When the paper-jamming causing paper 401 is stopped, a paper is stopped at the time of the cover's opening, or a paper is stopped at the time of occurrence of an abnormality, forcedly continuing paper transport at the downstream side may cause troubles, such as folding, tearing, or roller abrasion (soil) on a downstream side paper. For example, at the stoppage of an upstream processing unit, when it is determined that the trailing edge of the most downstream side paper 402 has not passed the stopped transport roller 5 or jamming of the paper-jamming causing paper 401 as a result of contact between the most downstream side paper 402 and the paper-jamming causing paper 401, it is concluded that the most downstream side paper 402 has a trouble such as folding, tearing, or roller abrasion (soil).
On the other hand, if the post-processing apparatus is brought to a full stop when the leading edge of the most downstream side paper 402 is located downstream of the paper ejecting roller 6, the paper ejecting roller 6 is not able to carry out the stop operation in time even if the most downstream side paper 402 is determined to be remained in the post-processing apparatus. Therefore, the paper is ejected onto the shift tray 202 after all or stopped in a state of being exposed out of the post-processing apparatus. When the paper ends up in such a state, the user may pull the paper out of the paper ejecting roller 6 and consider such a pulled-out paper as effective. In such a case, the same image formation and paper processing is carried out again in a recovery process, which results in redundant output.
In the present embodiment, preventing of redundant output in the recovery process is to be attained. Therefore, when the most downstream side paper 402 is at a position that may possibly lead to redundant paper output in the recovery process, only the most downstream side paper 402 is kept ejected onto the shift tray 202. At this time, the most downstream side paper 402 is regarded as the paper ejected normally and completely, and is not the subject of the recovery process. On the contrary, when the most downstream side paper 402 is at a position that does not lead to or less possibly leads to redundant paper output in the recovery process, all transport papers are stopped and are subjected to the recovery process. A specified position used for determining whether the most downstream side paper 402 is to be ejected out of the post-processing apparatus can be set based on various conditions such as a system configuration or an individual user. However, whether the most downstream side paper 402 is exposed out of the post-processing apparatus can be one preferable condition.
7.4 Detection of Position of Ejection Paper
The operations described in 7.1 and 7.3 are carried out to prevent the user from mistakenly considering a noneffective paper as effective. In these operations, it is necessary to exactly detect the position of the leading edge of an ejection paper at the stoppage of the post-processing apparatus. The shift paper ejecting sensor 303 is disposed near the paper ejecting roller 6, and is capable of detecting the leading edge of a transport paper. The position of the leading edge of a paper is detected easily by detecting an amount of rotation of the paper ejecting roller 6 after detection of the leading edge. Therefore, in the present embodiment, an amount of drive of the shift paper ejecting motor (not shown) that drives the paper ejecting roller 6 is to be detected after the shift paper ejecting sensor 303 detects the leading edge of a paper. In this case, if the shift paper ejecting motor is a stepping motor, the number of driving steps is to be counted. This enables detection of the position of the paper's leading edge after detection of the paper's leading edge.
7.5 Use of Transport Roller Having One-Way Clutch
It is preferable to stop an upstream transport roller for safety when paper-jamming, mechanical abnormality, or cover's opening occurs at the upstream side. In the present embodiment, a one-way clutch is disposed on the upstream transport roller (the transport roller 5 in
The paper post-processing apparatus PD having the above configuration carries out a stopping operation at the time of paper-jamming in the following manner. When paper-jamming occurs (Yes at Step S161), the presence/absence of a paper downstream of the paper-jamming causing paper 401 is checked (Step S162). When no paper is present (No at Step S162), all transport rollers are stopped (Step S165). When a paper is present (Yes at Step S162) and the leading edge of the most downstream side paper 402 is not located downstream of the paper ejecting roller 6 (No at Step S163), all transport rollers are stopped (Step S165). When a paper is present and the leading edge of the most downstream side paper 402 is located downstream of the paper ejecting roller 6 (Yes at Step S163), transport rollers other than the paper ejecting roller 6 are stopped to keep driving only the paper ejecting roller 6 (Step S164). This causes a stopped transport roller to rotate along with movement of the most downstream side paper 402, so that the most downstream side paper 402 is ejected by the paper ejecting roller 6.
When the cover is opened, as shown in
When a mechanical abnormality occurs, as shown in
7.6 Use of Transport Roller Having Small Friction Coefficient
The same operation as described in 7.5 is achieved when the friction coefficient of a transport roller is set to be smaller than that of the paper ejecting roller, instead of providing the transport roller with the one-way clutch. Therefore, the transport roller 5 can be one having a small friction coefficient.
When the transport roller 5 has a small friction coefficient, a paper is caused to slip over the transport roller 5 by the transport action of the paper ejecting roller 6 and thereby the paper is ejected out. Other operation procedures are the same as those described in connection with
As shown in
In this case, when the upper limit length of a paper acceptable to the paper post-processing apparatus PD is assumed as L meters, the friction coefficient of every transport roller that is other than the paper ejecting roller 6 and that is spaced L meters or less from the paper ejecting roller 6 is determined to be smaller than the friction coefficient of the paper ejecting roller 6. As a result, for every acceptable paper, the most downstream side paper 402 is ejected completely without being damaged when the operations described in the flowcharts of
7.7 Transport Operation for Paper Long in Transport Direction
According to the operations described in 7.1 and 7.3, the paper ejecting roller 6 ejects a paper nipped by the paper ejecting roller 6 when the leading edge of the most downstream side paper 402 is located downstream of the paper ejecting roller 6. In contrast, in this example, when such a stoppage condition as paper-jamming, cover's opening, and abnormality occurs, transport rollers are stopped to prevent ejection of all papers out of the post-processing apparatus when the leading edge of the most downstream side paper 402 is located downstream of the specific position but the trailing edge of the most downstream side paper 402 is located upstream of the trailing transport roller (the transport roller 5). This suppresses a cost increase, and prevents complete ejection of the most downstream side paper 402 that has been damaged.
The paper post-processing apparatus PD having the above configuration carries out a stopping operation at the time of paper-jamming in the following manner. As shown in
When a paper is not present downstream of the paper-jamming causing paper (jammed paper) at Step S192, and if the leading edge of the most downstream side paper is located upstream of the paper ejecting roller 6 at Step S193 and the trailing edge of the most downstream side paper is located downstream of the transport roller that is upstream of the paper ejecting roller 6 at Step S194, all transport papers are stopped (Step S196).
In execution of the stopping operation at the time of the cover's opening, as shown in
In execution of the stopping operation at the time of occurrence of an abnormality, as shown in
When a paper is not present downstream of the paper-jamming causing paper at Step S222, and if the leading edge of the most downstream side paper is located upstream of the paper ejecting roller 6 at Step S223 and the trailing edge of the most downstream side paper is located downstream of the transport roller that is located upstream of the paper ejecting roller 6 at Step S224, all transport papers are stopped (Step S226).
The above operation control is carried out to prevent a cost increase and an abrasion on an image, and to prevent a user from mistakenly considering a noneffective paper as effective. To achieve this, it is necessary to exactly detect the position of the leading edge and the trailing edge of an ejection paper at the stoppage of the post-processing apparatus. The position of the trailing edge of a paper is detected by the paper trailing edge detecting sensor 306 disposed near the transport roller 5 as described in connection with
7.8 Reverse Operation of Paper Ejecting Roller
As described above, when a paper comes to a stop in a state of being exposed out of the post-processing apparatus, the user may pull the paper out of the paper ejecting roller and considers the paper as effective. In this example, when the paper ejecting roller is forced to be stopped because the leading edge of the most downstream side paper 402 is exposed out of the post-processing apparatus, the paper ejecting roller 6 is reversed to pull the exposed paper into the post-processing apparatus to prevent the user from pulling the paper from the paper ejecting roller 6.
In the present embodiment, after a paper remaining in the post-processing apparatus is removed, processing of the remaining paper and image formation are carried out again. Therefore, it is possible to carry out the recovery process without redundant paper output after the stoppage of the post-processing apparatus due to occurrence of paper-jamming, cover's opening during paper transport, or mechanical abnormality.
According to the present embodiments, the following effects are to be attained.
1) A stopping operation is carried out for preventing redundant output in the recovery process. Therefore, it is possible to prevent redundant paper output to be performed when the recover process is carried out after the stoppage of the post-processing apparatus due to paper-jamming, cover's opening during paper transport, and mechanical abnormality detection.
2) When the transport operation is stopped because a paper is exposed out of the post-processing apparatus, a user may pull the paper out of the paper ejecting roller to consider the paper as effective. If the paper is exposed out of the paper ejecting roller toward the downstream side to a small extent, a user is not likely to consider a paper as effective. However, even in such a case, if a user pulls out the paper, a redundant output is carried out. To deal with such a situation, in the present embodiment, whether the paper ejecting operation is continued is determined based on whether the leading edge of the paper is out of the post-processing apparatus. This prevents redundant paper output when the recovery process is carried out.
3) The shift paper ejecting sensor capable of detecting the passage of the leading edge of a paper is disposed near the paper ejecting roller. This enables exact detection of the position of the leading edge of an ejection paper.
4) When only the most downstream side paper is completely ejected in each case of transport stoppage, if the trailing edge of the most downstream side paper has not passed through a transport roller other than the paper ejecting roller, the transport roller is not allowed to stop. However, considering safety at the time of paper-jamming at the upstream side, mechanical abnormality, or cover's opening, it is preferable to immediately stop the transport roller on the upstream side. In the present embodiment, the drive system of the transport roller is provided with a one-way clutch. Because of this, the paper ejecting roller alone can eject most downstream side paper completely even if the transport roller at the upstream side is stopped immediately.
5) In the present embodiment, the friction coefficient of a transport roller other than the paper ejecting roller is set to be smaller than the friction coefficient of the paper ejecting roller. Because of this, the paper ejecting roller alone can eject most downstream side paper completely even if the transport roller at the upstream side is stopped immediately.
6) Even when the trailing edge of the most downstream side paper has not passed through a transport roller other than the paper ejecting roller in each case of transport stoppage, only the most downstream side paper is ejected completely. However, use of the one-way clutch leads to an increase in the cost of the post-processing apparatus. Furthermore, reducing the friction coefficient of the transport roller to allow the paper to be dragged out may cause an abrasion on an image depending on the state of the image or the paper. Besides, when the most downstream side paper is exposed out of the post-processing apparatus in each case of transport stoppage, if an extent of exposure is small, a user is not likely to pull the paper out of the paper ejecting roller. For these reasons, in the present embodiment, when the trailing edge of the paper is located upstream of the most downstream side transport roller other than the paper ejecting roller, transport rollers are stopped to prevent ejection of all papers out of the post-processing apparatus. This prevents redundant output in the recovery process without increasing costs and abrasion on an image.
7) The paper trailing edge detecting sensor capable of detecting the passage of the trailing edge of a paper is disposed near the most downstream side transport roller other than the paper ejecting roller. This enables exact detection of the position of the trailing edge of a paper to be ejected.
8) When the paper ejecting roller is forced to be stopped because the leading edge of a paper is exposed out of post-processing apparatus, the exposed paper is pulled into the post-processing apparatus by reversing the paper ejecting roller. This prevents an accident that the user pulls the paper out of the paper ejecting roller to consider the paper as effective when the paper ejecting roller is stopped with the paper exposed out of post-processing apparatus.
9) After a paper remaining in the post-processing apparatus is removed, processing of the remaining paper and image formation are carried out again. As a result, the recovery process is carried out without redundant paper output after the stoppage of the post-processing apparatus due to occurrence of paper-jamming, cover's opening during paper transport, and mechanical abnormality.
While preferred embodiments have been described heretofore, those skilled in the art will be able to offer various alternatives, modifications, and variants based on the disclosed contents of the present specification. These alternatives, modifications, and variants are included in the scope of the invention that is specified by the accompanying clams.
According to an aspect of the present invention, it is possible to prevent a paper being transported by transporting rollers from being damaged by folding, tearing, roller abrasion (soil), or the like even when the trailing edge of the paper has not passed a roller that is forced to be stopped due to an event that causes stopping of transport rollers.
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.
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