Abstract:
A paper feeding apparatus for an office automation system constructed to accommodate the storage of paper, a sheet feeder that guides paper to travel in a selected direction of travel, and a device that aligns paper that is being stored to conform to the state of the feeder.

Description:
CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from applications entitled Paper Feeding Apparatus For Office Automation System earlier filed in the Korean Industrial Property Office on Mar. 31, 1998, and there duly assigned Serial No. 11319/1998, and a second application entitled Paper Feeding Apparatus For Office Automation System and earlier filed in the Korean Industrial Property Office on May 29, 1998 and there duly assigned Serial No. 19919/1998. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet feeding apparatus and processes generally, and, more particularly, to a paper feeding apparatus and process in an office automation system capable of preventing sheets of paper from deviating from the paper feeding apparatus during continuous feeding of the paper, realigning the paper for feeding while preventing more than one sheet from being fed and preventing occurrence of curl in the stationary sheets of paper. 
     2. Description of the Related Art 
     Office automation machinery includes image formation devices such as printers, facsimile transmission units, photocopies and scanners. Printers are used for creating documents by printing characters, symbols and images onto one exposed surface of a printable medium such as a cut sheet of paper that is fed into and transported through the printer, while scanners are used for reading and storing in image files characters, symbols and images from documents that have been fed into the scanner. A multi-functional office automation machine with the functions of both a printer and a scanner makes it possible for users to selectively use either one of these functions, in accordance with the desires of the user. 
     Since the aforementioned printers, scanners, or multi-functional office automation machines require the feeding of paper during printing, facsimile transmission, photocopy duplication or scanning, they are often equipped with some sort of paper feeding apparatus that feeds one or more sheets of paper to the machine. Papers stored in a paper tray, for example, are fed by the paper feeding apparatus, and are usually moved to a printing unit of the printer, photocopier or facsimile, or to the scanning unit of the scanner by the coordinated operation of several feed rollers. After images and characters of the document are either printed on the blank surface of the paper or read from the printed side of the document, the paper is then extracted through an outlet of the machine. 
     When printing or scanning is preformed by such paper feeding apparatus, the paper is usually continuously fed by one sheet after another sheet, beginning with the uppermost sheet in the stack of paper that is held by the apparatus. We have noticed however, that conventional paper feeding apparatus has an undesired tendency to simultaneously feed those sheets of paper that are stacked just below the uppermost sheet, together with the uppermost sheet, during the feeding operation of the apparatus. We have also found that this phenomenon occurs when the paper below the uppermost sheet is very thin, or has a curl at a particular portion of the sheet. I have also discovered that when a sheet of paper with such a curl is in contact with a separation finger that is disposed at both lower portions of the paper tray, the ears of the paper are all too often folded. This, in my opinion, frequently causes that sheet of paper to precipitate a problem during the course of the feeding operation, such as a paper jam within either the feeding apparatus for the image formation machine, a printing error, or scanning error. Moreover, when the paper is stored for a long time in a state standing at the feeding apparatus, a few sheets of the paper are abnormally fed to the separation finger along the resistance rib of the main frame of the paper feeding apparatus. Therefore, when the paper which is very thin or has a curl, is fed under the circumstance, the aforementioned abnormal paper feeding occurs. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved process and apparatus for serially feeding cut sheets of paper from a stack of the paper. 
     It is another object to prevent more than one sheet of paper stored in a standing state on the paper feeding plane of a paper feeding apparatus, from being fed during a feeding cycle for one sheet, by adding a simple element to the apparatus. 
     It is still another object to prevent a few sheets of the paper from being abnormally fed into the paper feeding apparatus during a feeding cycle for a single sheet, by automatically realigning the remaining sheets below the uppermost sheet while feeding the uppermost sheet of paper. 
     It is yet another object to prevent a cam and a lever that are employed to prevent occurrence of paper curl from deviating from their normal positions. 
     It is still yet another object to provide apparatus and process in an office automation system capable of preventing sheets of paper from deviating from the paper feeding apparatus during continuous serial feeding of the paper from a stack, realigning paper remaining in the stack, preventing more than one sheet from being fed, and preventing occurrence of curl in the paper awaiting feeding. 
     These and other objects may be attained with a paper feeding process and device that may be installed in office automation apparatus. As contemplated in the practice of the principles of the present invention, the process may be implemented with a device that includes a storage tray able to hold a stack of cut sheet of paper, a feeding mechanism that serially feeds single sheets of paper from the stack in a selected direction, and an alignment mechanism that arranges sheets of paper remaining in the tray to conform to the state of the feeding mechanism. The alignment mechanism may be constructed with a first rotary shaft disposed over and spaced-apart by a selected distance from the tray, and a first eccentric cam that is preferably coupled to the first rotary shaft, varying the position of those sheets of paper stored on the tray by its rotation. Also, an ascent and descent component part is positioned at a contact face with the first eccentric cam, to ascend and descend relative to the pick-up plate of the tray in consonance with the rotation of the first eccentric cam. 
     The alignment mechanism may be constructed with a first lever that is rotated between a first position for supporting one-sided end of a sheet of paper so that the paper is aligned and a second position where support of the paper is released. The first lever is rotated in accordance with the feeding state of the feeding mechanism. 
     The tray may be constructed with a second pick-up plate that ascends and descends, a second rotary shaft disposed spaced-apart by a selected distance from the pick-up plate, and a second eccentric cam coupled to the second rotary shaft, for varying the position of the paper stored on the pick-up plate through the rotation of the second eccentric cam. 
     The alignment mechanism may be constructed with a guide lever that directs the second cam to rotate along a predetermined path of rotation. The first lever is selectively engaged with the feeding mechanism. 
     Selectively, the principles of the present invention may be practiced with a paper feeding device constructed with a first driving mechanism providing a reciprocating driving force that is generated simultaneously with the operation of the feeding mechanism, so that the first lever is rotated when the reciprocating driving force is applied through a rod that is hinge-coupled to the first lever. Preferably, either a cylinder solenoid or an electric motor may be used as the driving mechanism. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of this invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
     FIG. 1 is a perspective view of a paper feeding apparatus for an office automation system constructed as a first preferred embodiment of the principles of the present invention; 
     FIG. 2 is an exploded perspective view of the rear of the main frame shown in FIG. 1; 
     FIG. 3 is a partial sectional view showing one operational state with the hemi-circular cam and the guide lever in contact with each other; 
     FIG. 4 is a simplified sectional view of FIG. 1 showing an operational state in which the paper is aligned; 
     FIGS. 5 and 6 are simplified sectional views of FIG. 1 showing an operational state in which the paper is fed; 
     FIG. 7 is a simplified sectional view of the paper feeding apparatus constructed as a second preferred embodiment of the present invention; 
     FIG. 8 is a simplified sectional view of the paper feeding apparatus of the second preferred embodiment of the present invention, showing one operational state while paper is being fed; 
     FIG. 9 is a partial sectional view of the paper feeding mechanism constructed as a third embodiment of the present invention; 
     FIG. 10 is a perspective view of a rotary shaft in a paper feeding mechanism constructed as a fourth preferred embodiment of the present invention; 
     FIG. 11 is a simplified sectional view of the paper feeding apparatus of FIG. 10, showing that the paper is aligned by the stop lever; and 
     FIG. 12 is a simplified sectional view of the paper feeding apparatus of FIG. 10, showing an operational state while paper is fed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those having skill in the art. 
     Referring first to FIGS. 1 and 2, a paper feeding apparatus constructed as a first preferred embodiment of the principles of the present invention includes a main frame  10  and a pick-up plate  12  which ascends and descends with respect to the bottom plate of the main frame  10 . A spring (not shown) is disposed between the pick-up plate  12  and the bottom plate of the main frame  10  in order to provide an elastic force therebetween. 
     A resistance rib  18  is disposed standing at one end of the bottom plate of the main frame  10  and supports a paper supplied on the pick-up plate  12 . The resistance rib  18  has a plurality of projection pieces  16  that are projected from the surface of the resistance rib  18  with a constant interval. The plurality of projection pieces  16  forms a paper end supporting plane  14  for supporting the ends of the paper mounted on the pick-up plate  12  at a selected position. 
     A pair of side frames  20  are disposed to both side walls of the bottom plate of the main frame  10 , and coupled to the main frame  10  as one body. A rotation shaft (hereinafter referred to as “first rotary shaft”)  22  is coupled to both the side frames  20 . Two feed rollers  24  of hemi-circular plated shape are coupled to the first rotation shaft  22  apart from each other by a predetermined distance. Each of the two feed rollers  24  has a thin coated film of robber or urethan in order to enhance the feeding force of papers. 
     A cam assembly  32  including an inner cam  28  and an outer cam  30  is also coupled to the first rotation shaft  22 . The inner cam  28  is disposed on the inner wall of one sided frame  20  and is applied for changing the position of the pick-up plate  12 . The outer cam  30  disposed on the outer wall of the one side frame  20  and is coupled with a ratchet lever  36  disposed at the outer portion of the one sided frame  20 . 
     An eccentric hemi-circular cam  38  is coupled to one sided end of the first rotation shaft  22  to be adjacent to the other sided frame  20 . An ascent and descent member  39  for ascending and descending the pick-up plate  12  is disposed at one sided edge of the pick-up plate  10  as one body with the pick-up plate  12 . The ascent and descent member  39  has an upper surface in which one end of the upper face thereof is curved upward, the upper surface being in contact with the outer circumferential surface of the eccentric hemi-circular cam  38  during the rotation of the eccentric hemi-circular cam  38 . A lever rod is located at the rear of resistance rib  18 . As shown in FIG. 2, the lever rod  40  is coupled by a pair of clips  42  to a bent portion of the rear of the resistance rib  18 . Each of the pair of clips  42  includes a pair of extended portions each of which is firstly bent at an obtuse angle and is then secondly bent at an acute angle. Here, the pair of firstly bent portions of the clips  42  are respectively inserted into a pair of through holes  44  each of which is formed to be symmetric with respect to the main frame  10  and the resistance rib  18 , thereby supporting the lever rod  40 . Two stop levers  46  are respectively coupled to the lever rod  40  at the right angle, one being coupled to the mid portion of the lever rod  40  and the other to one end of the lever rod  40 . At an portion adjacent to the other end of the lever rod  40 , a guide lever  48  is coupled to the lever rod  40 . A spring  50  is also coupled to the other end of the lever rod  40 . The spring  50  has both ends which are extended to be crossed each other, thereby providing the stop lever  46  and the guide lever  48  with an elastic force. Here, the stop lever  46  has an end bent toward the standing paper mounted on the pick-up plate  12 , and is rotated simultaneously with the movement of the guide lever  46 . 
     The guide lever  48  and the hemi-circular cam  38  each has projections  52 ,  54  at their ends that are partially projected therefrom as shown in FIG. 3 such that they do not engage crisscross each other during relative displacement movement. Through holes  60 ,  62  are respectively formed at selected portions of the resistance rib  18  that correspond to the guide lever  48  and the pair of stop levers  46 . A paper size controller  56  is equipped to the main frame  10  and is freely moved along the direction normal to the feeding direction of papers to align the papers according sizes of the papers as fed. A paper supporting member  58  supports the upper portion of the papers mounded on the pickup plate  12 , and length thereof can be freely controlled. 
     In the aforementioned paper feeding apparatus, the first rotation shaft  22  is rotated as a rotation power that is provided from a motor (not shown) is applied to the first rotation shaft  22 . The rotation of the first rotation shaft  22  allows the feed roller  24  to be rotated, and thereby each of the levers  46 ,  48  is operated simultaneously with the rotation of the first rotation shaft  22 . 
     When some sheets of the paper  64  are stocked on the pick-up plate  12 , the hemi-circular cam  38  is positioned such that the section thereof is normal to the surface of the feeding paper  64  prior to the feeding of the paper  64  as shown in FIG. 4 The hemi-circular cam  38  is engaged with the ascent and descent member  39  in the descent state. In the descent state of the pick-up plate  12 , the paper  64  is separated by a descent distance from the feed roller  24 . At this time, the stop levers  46  passes through the through holes  62  by the elastic force of the spring  50 , and are then projected to support the ends of the paper  64 , thereby preventing paper  64  that is not in the feeding state from being abnormally fed. At this time, the guide lever  48  is placed to be adjacent to the first rotation shaft  22  by rotating simultaneously with the stop lever  46 . 
     The paper  64  is supported upward by the paper end supporting plane  14  of the resistance rib  18 , and paper which ends thereof are unevenly arranged are evenly aligned by the stop lever  46 . 
     The uppermost sheet  64   a  of the paper  64  is continuously fed between a pair of rollers  66   a ,  66   b . Here, feeding of the paper  64  into the region below feed roller  24  is not related with the feed roller  24  under the state of FIG.  4 . 
     As the first rotation shaft  22  is rotated clockwise from the state of FIG. 4, the feed roller  24  and the hemi-circular cam  38  are accordingly rotated with the first rotation shaft  22 . As the hemi-circular cam  38  is rotated clockwise from the state of FIG. 4 by a selected angle, the ascent and descent member  39  is released from the state supported by the hemi-circular cam  38 , and accordingly the pick-up plate  12  ascends by the elastic power of the lower spring (not shown), whereby the pick up plate  12  is in contact with the uppermost sheet  64   a  of the feeding paper  64 . Thereafter, as the feed roller  24  is further rotated clockwise over a critical angle, the uppermost sheet that is in contact with the hemi-circular surface  26  of the feed roller  24  is fed between the roller  66   a ,  66   b . That is, as the first rotation shaft  22  is rotated clockwise by a predetermined angle from the state of FIG. 4, the pick-up plate  12  is released from the state pressed by the hemi-circular cam  30  as shown in FIG. 5 and thereby feeding of the paper  64  starts. 
     From the release state of the pick-up plate  12  as shown in FIG. 5, the hemi-circular cam  38  pushes the guide lever  48  toward the feeding direction of the paper  64 , and thereby the guide lever  48  is pushed counterclockwise. The stop levers  46  are also rotated counterclockwise and are extracted from the through hole  60  as the guide lever  48  is rotated, and thereby upward support of the paper  64  by the stop lever  46  is released. Under the circumstance, the feed roller  24  feeds the uppermost sheet  64   a  downward. 
     During the feeding of the uppermost sheet  64   a  as shown in FIG. 5, the first rotation shaft  22  continues to be rotated clockwise. The feed roller  24  and the hemi-circular cam  38  are also rotated as the first rotation shaft  22  is rotated, as shown in FIG.  6 . By the rotation of the feed roller  24 , the uppermost sheet  64   a  continues to be fed, and the hemi-circular cam  38  is guided along the inner curvature path of the guide lever  48  to be rotated. 
     As shown in FIG. 3, the guide lever  48  and the hemi-circular cam  38  each has a stepped end to be engaged with each other. Therefore, it is avoided that the guide lever  48  deviates from the end of the hemi-circular cam  38 . Selectively, it can be constructed that the guide lever  48  has a projection rail and the hemi-circular cam  38  which is engaged with the projection rail has a recess rail, and vice-versa to obtain the same effect as that provided by the embodiment illustrated by FIG.  3 . Although not shown in the drawings, the ascent and descent member  39  of the pick-up plate  12  that is in contact with the end of the hemi-circular cam  38  can be formed to have such a shape corresponding to the shape of the hemi-circular cam  38  and the shape of the end thereof. While the hemi-circular cam  38  is guided by the guide lever  48 , the stop lever  46  is not projected upward and maintains the present position. 
     As the first rotation shaft  22  is further rotated clockwise by a predetermined angle from the state of FIG. 6, engagement between the hemi-circular cam  38  and the guide lever  48  is released. Accordingly, the stop lever  46  again passes through the through holes  62  of the resistance rib  18  by the elastic force of the spring  50 , to thereby prevent papers right below the uppermost sheet  64   a  from being fed following the uppermost sheet  64   a.    
     As the first rotation shaft  22  is still further rotated clockwise by a predetermined angle from the state of FIG. 6, the paper feeding device is restored to the initial state of FIG.  4 . That is, the hemi-circular cam  38  again presses the ascent and descent member  39  such that the pick-up plate  12  descends. Resultantly, such a state that the paper below the uppermost sheet is pushed upward is released, and thereby the stored papers on the pick-up plate  12  is again aligned. 
     The aforementioned paper feeding device repeats the steps of FIG. 4 to FIG. 6, and the paper is fed by one sheet during such a cycle. Prior to feeding of the paper below the uppermost sheet after the uppermost sheet has been fed, the paper on the pick-up plate  12  is realigned. At this time, since the stop lever  46  supports the ends of the paper, feeding more than one sheet of he paper and curl generation are prevented. That is, the paper that is periodically fed is realigned by the ascent and descent of the pick-up plate  12 , and simultaneously the end of the paper is also realigned by the stop levers  46  during the realignment of the paper, resulting in the prevention of the curl generation. 
     Thus, according to the above first embodiment, through the reinforcement of simple appliance, it is prevented that paper more than one sheet is abnormally fed and paper having a curl is abnormally fed, resulting in the prevention of the skew, paper being not fed, and paper jams. Meanwhile, so as to maximize such functions like the prevention of the curl generation and the paper support, the stop lever  46  can be varied in various shapes. For example, the stop lever  46  can be bent at least once such that the bent portion thereof has an obtuse angle as shown in FIGS. 7 and 8. 
     FIGS. 7 and 8 show the paper feeding apparatus according to a second embodiment of the present invention. 
     Referring to FIGS. 7 and 8, a stop lever  46   a  is coupled to a rotation shaft (hereinafter referred to as “second rotation shaft”)  40   a  and can be structured such that it is pushed or pulled by a rod  72  of a solenoid cylinder  70 . Specifically, the mid portion of the stop lever  46   a  is hinge-coupled to the rod  72  of the solenoid cylinder  70 . Rod  72  pulls the stop lever  46   a  as shown in FIG. 7 when the paper starts to be fed, and pushes the stop lever  46   a  as shown in FIG. 8 when some sheets of papers has been fed or is stored. Through use of such the stop lever  46   a  driven by the solenoid cylinder  70 , it is prevented that paper more than one sheet of the paper supported by the resistance rib  18  is fed, the paper is curled, and the curled paper is abnormally fed. 
     Similarly to FIGS. 7 and 8, as a third embodiment to drive the stop lever  46   a , another means such as an electric motor can be selectively used. Specifically, as shown in FIG. 9, a second rotation shaft  40   b  having a stop lever  46   b  is established at the rear of the resistance rib  18 . The stop lever  46   b  is rotated as the second rotation shaft  40   b  is rotated, and goes in and out through the through holes  62  formed in the resistance rib  18 . A gear  80  with large diameter (hereinafter referred to as “large gear”) is coupled to one edge of the second rotation shaft  40   b  and a gear  82  with small diameter (hereinafter referred to as “small gear”) is engaged with the large gear  80 . The small gear  82  is coupled to a shaft  84  of a electric motor  86 . Here, the electric motor  86  is constructed to have a specific rotation number with respect to the clockwise or counterclockwise rotation. 
     When the electric motor  86  is rotated clockwise or counterclockwise, the small gear  82  is firstly rotated at a first specific rotation number, the large gear  80  is rotated as the small gear  82  is rotated, and the stop lever  46   b  is rotated clockwise or counterclockwise as the large gear  80  is rotated. 
     Like the previous embodiments, through the application of the electric motor  86  for driving the stop lever  46   b , it is prevented that the paper below the uppermost sheet is abnormally fed during one cycle and paper having a curl are normally fed, resulting in the prevention of the skew, paper being not fed, and the occurrence of jams during the feeding of the paper. 
     The rotation shaft according to the present invention can be also varied in various shapes. FIG. 10 shows a rotation shaft (hereinafter referred to as “third rotation shaft”)  40   c  according to a fourth embodiment of the present invention. For convenience and ease of understanding, description for the same elements as previous previously in the discussion of other embodiments will be omitted in the following paragraphs. 
     Referring to FIG. 10, there is provided a pair of stop levers  46   c . The pair of stop levers  46   c  are bent along the same direction and are apart from each other by a selected distance. The stopper  88  is disposed at mid portion between the pair of stop levers  46   c , and is formed as one body with the third rotation shaft  40   c . The stopper  88  has a projected portion  90  at a side wall thereof, the projected portion  90  is projected toward the feeding direction of the paper. The third rotation shaft  40   c  is also disposed at the rear of the resistance rib  18  as shown in FIGS. 11 and 12. The stopper  88  is disposed to pass through the through hole formed in the resistance rib  18 . Like the first embodiment, the third rotation shaft  40   c  is coupled to gears and motor, and is driven to be rotated clockwise or counterclockwise by the rotation power that is supplied from the motor and gears. 
     The third rotation shaft  40   c  is rotated at the rear of the resistance rib  18 , the stop levers  46   c  go in and out through the through holes formed in the resistance rib  18  as the third rotation shaft  40   c  is rotated, and the stopper  88  also goes in and out through a groove formed in the main frame  10 . 
     Like the first and second embodiments, when the papers are not fed and are stored on the pick-up plate  12  in the paper feeding apparatus according to the fourth embodiment, the stop lever  46   c  is rotated as the third rotation shaft  40   c  is rotated clockwise, to thereby align the ends of the papers that are caught by the paper end supporting plane  14 . At this time, the pick-up plate  12  is in the descent state. Afterwards, the ends of the paper  64  that are scattered while the uppermost paper is fed, is aligned by contacting with the inner surface of the bent stop lever  46   c  in rotation. 
     On the contrary, when the paper  64  is fed as shown in FIG. 12, the stop lever  46   c  is rotated counterclockwise as the third rotation shaft  40   c  is rotated counterclockwise and thereby the alignment state of the papers  64  aligned by the stop lever is released. Accordingly, the uppermost sheet  64   a  of the stored papers is in contact with the circular surface of the feed roller  24  and is then fed between the rollers  66   a  and  66   b . At this time, the pick-up plate  12  is in the ascent state. 
     The rotation radius of the third rotation shaft  40   c  is determined by the stopper  88 . Specifically, the projected portion  90  of the stopper  88  is rotated counterclockwise as the third rotation shaft  40   c  is rotated. During the rotation of the projected portion  90 , the projected portion  90  is caught by the paper end supporting plane  14 . 
     The aforementioned paper feeding apparatus may be applied not only to a typical document printer, but may also be applied to all paper feeding apparatus for an office automation system including a multi-functional machine that integrates the functions of a printer, a scanner and a facsimile transmission unit. 
     As described previously, the paper feeding apparatus of the present invention prevents the feeding paper from being curled by supporting the paper by the pair of stop levers, resulting in the prevention of the skew, paper being not fed, and paper jams. In addition, since unnecessary feeding of the paper below the uppermost sheet among the stored paper is prevented by the operation of the stop levers, occurrence of the skew or paper jam can be prevented. Moreover, since the hemi-circular cam and the guide lever have a projection structure corresponding to each other, it is prevented that the paper deviate from the fed state, resulting in maximizing the reliability in the paper feeding. Furthermore, since the curl generation of the paper for the feeding and abnormal paper feeding are prevented by adding a simple structured element, the fabrication cost is lowered. 
     The principles of this invention has been described in the foregoing paragraphs with reference to the several illustrated embodiments, as providing an apparatus and process that may be easily incorporated into office automation systems such as printers, scanners, photocopiers and facsimile transmission units, to prevent sheets of paper from deviating from the paper feeding apparatus during continuous, serial feeding of the sheets and realigning the sheets for feeding, while preventing more than one sheet from being fed into the apparatus and preventing occurrence of curl in the paper in the non-feeding state. It is evident, however, that many alternative modifications and variations will be apparent to those having skill in the art in light of the foregoing description. By way of example, although the foregoing embodiments have been described as applied to the handling, feeding and alignment of cut sheets of paper, the principles of the present invention may also be applied to other items of flat printable media such Mylar and overhead projection transparencies. Accordingly, the present invention embraces all such alternative modifications and variations as fall within the spirit and scope of the appended claims.