Abstract:
For separation and feeding of sheets of the recording carrier, these sheets are supplied stacked in a cassette. An advance head ( 18 ) sits on the stack with advance rollers ( 20 ), which is mounted on the free end of a pivotable arm ( 22 ). In order to be able to insert the cassette accommodating the stack and remove it, a release mechanism is provided that is operated by the cassette. For this purpose, the arm ( 22 ) is mounted on a slide ( 28 ) that is pulled into a release position by tension springs ( 32 ). A pusher ( 44 ) is also provided on the slide ( 28 ) that raises the arm ( 22 ) under spring force. With the cassette, an operating pin ( 58 ) is inserted into the release mechanism. The pin ( 58 ) pushes the slide ( 28 ) against the force of spring ( 32 ), into the operating position of arm ( 22 ) and pushes the pusher ( 44 ) into a position that releases the arm ( 22 ) for lowering onto the stack.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority to German Patent Application No. 10 2004 038 971.3, which was filed on Aug. 10, 2004, and is incorporated herein by reference in its entirety.  
       TECHNICAL FIELD  
       [0002]     The invention concerns a device for separation and feeding of sheets of a recording carrier.  
       BACKGROUND  
       [0003]     A device of this type is known from DE 199 50 307 C1. In this known device, the sheets of the recording carrier are supplied in a cassette as an essentially horizontal stack. The cassette is pushed into a receiving space, for example, of an office machine or sheet feeder for an office machine. An advance head with a drivable advance roller lies on the stack, which pushes the uppermost sheet of the stack against a rising slope of the cassette, so that the front edge of the sheet runs up the slope and is separated from the next sheet of the stack. The uppermost sheet so separated is then grasped by the transport device and fed to the office machine, for example, a printer, copier or the like. The advance head is mounted on a free end of an arm, mounted to pivot on an inside wall of the receiving space and extending across the feed direction over the stack. The advance head can follow the diminishing height of the stack by means of the pivotable arm.  
         [0004]     In order to be able to pull out the cassette from the receiving space and push it back into the receiving space, for example, when the cassette is changed or is to be loaded with a new stack of sheets, the arm with the advance head must be raised, so that the cassette can be pulled out beneath the advance head and, if necessary, pushed back in again with a new stack beneath the advance head. For this purpose, the known device has a release mechanism with a lift lever. The lift lever is pivoted by the pushed-in cassette, so that it releases the arm and this can be lowered onto the stack. If the cassette is pulled out, it releases the lift lever and this is pivoted under the influence of a spring, so that it raises the arm with the advance head. The release mechanism causes only lifting of the arm with the advance head upward. This lifting is not sufficient in those cases when the advance head is situated right against the slope of the cassette with the advance roller, on which the stack comes in contact with its front edge.  
       SUMMARY  
       [0005]     The underlying object of the invention is to improve a device of the type just mentioned, so that the arm with the advance head guarantees greater free space for removal and insertion of the cassette.  
         [0006]     This object can be solved by a device for separation and feeding of sheets of a recording carrier, with a cassette insertable into a receiving space, which receives the sheets in an essentially horizontal stack and has a rising slope, on which the stack lies with its edge facing the free direction, with an arm mounted to pivot on an inside wall of the receiving space and protruding above the stack of the inserted cassette, with an advance head arranged on the free end of the arm, which can be lowered onto the stack by pivoting of the arm and raised from the stack, with at least one advance roller mounted in the advance head, which sits on the uppermost sheet of the stack when the advance head is lowered and can be driven, in order to push the uppermost sheet up for separation on the slope, and with a release mechanism that raises the arm from the stack when the cassette is moved from the receiving space, and which is operated by the cassette inserted into the receiving space, in order to release the arm for lowering onto the stack, wherein the arm is mounted to pivot on a slide that is arranged movable on the inside wall essentially parallel to the surface of the stack, and is moved away from the slope by a spring force, a pusher is arranged moveable on a slide, which engages on the arm and is biased by a spring force in a position that raises the arm, and wherein at least one operating protrusion arranged in a cassette acts on the slide during insertion of the cassette and moves it against the spring force against the slope and acts on the slide and moves it against the spring force into the position that releases the arm.  
         [0007]     The operating protrusion can be formed as a pin protruding from a cassette in the insertion direction, which acts on the slide and pusher via wedge surfaces. The slide may have a passage opening for the pin, and a wedge surface can be formed in the passage opening, which the pin encounters during insertion into passage opening, in order to move the slide against the spring force. The pin may have a conical tip that penetrates the operating opening and produces the wedge effect for movement of the pusher. The operating opening can be formed in a thrust plate mounted to move on the slide, and which can be made to cover the passage opening of the slide, and the thrust plate can be connected to the pusher via a pivotable lever. The lever can be designed as a two-arm lever and may convert the pushing path of the thrust plate to a larger pushing path of the pusher. The arm, together with a parallel rod, may form a parallel guide for the advance head, the parallel rod can be lengthened beyond its bearing on the slide, and the pusher may engage on this lengthened end of the parallel rod. The lengthened end may pass through an elongated hole of the pusher, may be freely movable in this elongated hole in the release position and can be entrained by the end of the elongated hole when the pusher is moved into the position that raises the arm under the spring force.  
         [0008]     In the device according to the invention, the arm with advanced head is mounted to pivot on a slide guided on the inside wall of the receiving space, parallel to the surface of the stack. A pusher is mounted on this slide, which engages on the arm, in order to raise it or release it for lowering. The arm can therefore not only be raised upward by the slide, but can also be moved away from the slope by means of the slide. The slide is then biased by spring force, so that it is moved away from the slope, and the pusher is biased by spring force, so that it raises the arm. If the cassette is pulled out from its operating position in the receiving space, the arm is raised, on the one hand, by the spring-loaded pusher, and moved away from the slope, on the other hand, by the spring-loaded slide. The arm and the advance head come into a position on this account, in which they are reliably moved out fully from the movement path of the cassette and any sheet stack accommodate in the cassette. Unhampered pulling out and reinsertion of the cassette is possible. The cassette has at least one operating protrusion, with which it engages with the release mechanism when the cassette is pushed into its operating position. The operating protrusion, in the first place, moves the slide against the slope, and, in the second place, moves the pusher against its spring load into the position, in which the pusher releases the arm for lowering.  
         [0009]     The operating protrusion is preferably designed as a pin arranged on the outside of the cassette facing the insertion direction of the cassette and protrudes from the cassette in this insertion direction. When the cassette reaches its operating position during insertion, this pin penetrates into the slide, during which the axial penetration movement of the pin is converted via a wedge surface into the displacement movement of the slide against its spring bias. The pin acts further during insertion via a wedge surface on the pusher, in order to move it against its spring force.  
         [0010]     It is readily apparent that two separate operating protrusions, for example, pins, can be used for displacement of the slide and pusher. In a preferred variant, the same pin is used, both for displacement of the slide and the pusher, during which this pin acts on the slide and pusher in succession during its axial movement.  
         [0011]     In an expedient variant, the slide is movable on guide rods. For mounting on the guide rods, the slide has a certain material thickness. The wedge surface is then expediently made on the slide, in which the wedge surface guarantees sufficient displacement movement of the slide, because of the material thickness.  
         [0012]     For movement of the pusher, a lever transmission is preferably used, so that a slight axial movement of the pin is converted to a larger displacement path of the pusher. The wedge surface for conversion of the axial path of the pin to the displacement path can be designed for this purpose as a conical tip of the pin. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     The invention is further explained below by means of a practical example depicted in the drawing. In the drawing:  
         [0014]      FIG. 1  schematically depicts the device with the cassette pulled out.  
         [0015]      FIG. 2  schematically depicts the device with the cassette insert.  
         [0016]      FIG. 3  shows the device with the cassette pulled out, in which only the pin for operation of the cassette is shown.  
         [0017]      FIG. 4  shows a view corresponding to  FIG. 3  during engagement of the pin in the release mechanism.  
         [0018]      FIG. 5  shows a view corresponding to  FIG. 3  with the completely inserted cassette.  
         [0019]      FIG. 6  shows a view corresponding to  FIG. 5 , in which the housing of the release mechanism is removed.  
         [0020]      FIG. 7  shows the device in the position of  FIG. 3 , viewed from the outside, in which the housing of the release mechanism is removed.  
         [0021]      FIG. 8  shows the device in the position of  FIG. 6 , viewed from the outside.  
         [0022]      FIG. 9  schematically depicts a top view of the device with the cassette pulled out.  
         [0023]      FIG. 10  shows a view corresponding to  FIG. 9 , with the cassette insert.  
         [0024]      FIG. 11  shows an outside view of operation of the pusher with the cassette pulled out.  
         [0025]      FIG. 12  shows a front view of the device in the position of  FIG. 11 .  
         [0026]      FIG. 13  shows an outside view of operation of the pusher with the cassette inserted.  
         [0027]      FIG. 14  shows a view corresponding to  FIG. 12 , with the cassette inserted. 
     
    
     DETAILED DESCRIPTION  
       [0028]     In order to supply an office machine, for example, a printer, copier or the like, with sheets of a recorded carrier, for example, paper sheets, these sheets are supplied in stack  10 . The stack  10  of sheets is accommodated essentially horizontally in a cassette  12  that is inserted into the receiving space of the device. The receiving space can be formed in the office machine itself or in a separate sheet feeder that can be mounted or added on to the office machine. Only an inside wall  14  of the receiving space is shown in the drawing.  
         [0029]     The cassette  12  has a slope  16  on its front side facing the feed direction of the sheets, which rises at an angle of about 20-25°, with reference to the vertical on the stack surface. The stack  10  lies with its front edge facing the feed direction on this slope  16 . An advance head  18  is positioned on the uppermost sheet of stack  10 , which engages frictionally with drivable advance rollers  20  on the uppermost sheet of stack  10 . The driven advance rollers  20  push the uppermost sheet of stack  10  with its front edge against slope  16 , so that the front edge of the uppermost sheet rises on slope  16  and is separated from the next sheet of stack  10 , so that it can be fed separately to further transport to the office machine. The advance head  18  is mounted on the free end of an arm  22  that is mounted to pivot on inside wall  14  in a pivot plane parallel to the plane of slope  16 . Since the arm  22  is freely pivotable, the advance head  18  lies freely on the uppermost sheet of stack  10  under the weight of the advance head  18  and arm  22  and can follow the changing height of stack  10 . The advance rollers  20  are movable in the advance head  18  against a spring force in the plane of stack  10 . Owing to arrangement of arm  22  and advance head  18  and the spring bias of the advance rollers  20 , these advance rollers  20  lie on the front end of the uppermost sheet in the feed direction and lie against the slope  16  with a certain spring bias, when the advance rollers  20  are not driven.  
         [0030]     As is apparent from  FIGS. 1 and 2 , the cassette  12  is pushed horizontally into the receiving space, perpendicular to inside wall  14 . In order to be able to push cassette  12  with a stack  10  into the receiving space or pull the inserted cassette out of the receiving space, the arm  22  with advance head  18  must be raised from stack  12  and cassette  12  far enough, that sufficient free space for removal and insertion of the cassette is formed.  FIG. 1  shows the arm  22  raised in this way with advance head  18 , in which the cassette  12  is partially withdrawn.  FIG. 2  shows the completely inserted cassette  12  with the lowered arm  22  and the advance head  18  sitting on stack  10 . In the operating position depicted in  FIG. 2 , the sheets can be removed separately from stack  10  and fed to the office machine.  
         [0031]     It is explained below how arm  22 , with advance head  18 , is raised automatically according to the invention, when the cassette  12  is removed from the receiving space, and lowered automatically onto stack  10 , when the cassette  12  is inserted into the receiving space.  
         [0032]     A release mechanism is arranged on the inside wall of the receiving space. The release mechanism is accommodated in a housing  24 , fastened with appropriate fastening devices  26  to the inside wall  14  of the receiving space.  
         [0033]     A slide  28 , guided to move on two guide bars  30 , is arranged on housing  24 . The guide bars  30  are mounted parallel to each other and at a spacing in housing  24 , so that they run parallel to the inside wall  14  and parallel to the surface of stack  10 . Tension springs  32  are fastened on one end to slide  28  and on the other end to housing  24  and pull the slide  28  on guide bars  30  in the direction pointing away from slope  16 . The arm  22  is mounted to pivot on the surface of slide  28  facing the receiving space by means of an obliquely positioned bearing axis  34 , perpendicular to the pivot plane of arm  22 . A parallel rod  36  is also arranged beneath arm  22  and parallel to it, which is mounted to pivot with a bearing  38  on slide  28 . The parallel rod  36  is pivotable in the same pivot plane as arm  22  and forms, with arm  22 , a parallel guide lying in the pivot plane that causes the advance head  18  to be moved up and down parallel during pivoting of arm  22 .  
         [0034]     Beneath guide rods  30 , the slide  28  has a passage opening  40  that passes through slide  28 , perpendicular to its plane, i.e., perpendicular to inside wall  14 . The passage opening  40  is designed on its inside wall, directed against slope  16  with a wedge surface  42 , that is most clearly visible in the depiction of  FIGS. 9 and 10 . The wedge surface  42  is arranged perpendicular to the plane of stack  10  and sloped, so that the passage opening  40  tapers from its inlet side facing the receiving space for cassette  12  toward the side facing inside wall  14 .  
         [0035]     A pusher  44  is arranged on the surface of slide  28  facing inside wall  14 , which is guided to move on this surface of slide  28  in the pivot plane of arm  22  and parallel rod  36 . The pusher  44  has an elongated hole  46  running in its displacement direction, which is penetrated by an end  48  of parallel rod  36 , lengthened beyond bearing  38 . On the lower end of pusher  44 , a tension spring  50  engages, whose other end is fastened to slide  28 . The tension spring  50  pulls the pusher  44  into its lower end position. On the lower end of the pusher  44 , one arm of a two-arm lever, mounted to pivot on slide  28 , is connected. The other arm of lever  52  is connected to a thrust plate  54 , guided to move parallel to pusher  44  on the surface of slide  28 . The thrust plate  54  has continuous operating openings  56 , perpendicular to the plane of slide  28 , which can be brought to cover the outlet side of passage opening  40  facing the inside wall  14 .  
         [0036]     Cassette  12  has, on its outside, which faces the inside wall  14  during insertion of cassette  12  into the receiving space, a pin  58  that protrudes in the insertion direction. The pin is designed essentially cylindrical and has a conically rounded tip  60 .  
         [0037]     If no cassette  12  is situated in the receiving space or the cassette is only partially inserted into the receiving space, the device assumes the position depicted in  FIGS. 3, 7 ,  9 ,  11  and  12 . The slide  28  is pulled by tension springs  32  on guide rods  30  in the direction opposite the sheet feed direction. Because of this, the arm  22  and advance head  18  mounted on slide  28  are pulled away from slope  16 . The tension spring  50  pulls the pusher  44  downward. The end  48  of the parallel rod  36  reaches the upper end of elongated hole  46  and is entrained by the pusher  44  and pulled downward. The parallel rod  36 , and with it arm  22 , are pivoted up, so that the advance head  18  is raised. A cassette  12 , possibly with stack  10 , can now be pulled out unhampered from the receiving space by arm  22  with advance head  18 , or inserted into the receiving space.  
         [0038]     If the cassette  12  is pushed further into the receiving space from the position depicted in  FIGS. 3, 7  and  9 , the pin  58 , with its tip  60 , initially reaches passage opening  40  through an opening  62  of housing  24 . Since the slide  28  is retracted by the tension springs  32 , the tip  60  of pin  58  encounters the sloped wedge surface  42 . On further insertion of pin  58  into the passage opening  40 , the tip  60  of pin  58  presses against the wedge surface  42  and, in so doing, pushes the slide  28  against the force of tension springs  32 , so that the arm  22  mounted on the slide  28  is moved with the advance head  18  against the slope  16 . This position is shown in  FIG. 4 . As soon as the pin  58  has fully penetrated the passage opening, the slide  28  reaches its inserted end position against the slope  16 . The tip  60  of pin  58  now encounters the side of slide  29  facing inside wall  15  from the passage opening  40  and enters the operating opening  56  of thrust plate  54 . As is apparent in  FIG. 11 , the operating opening  56  is initially pushed against the passage opening  40 , because the tension spring  50  has also moved the thrust plate  54  via lever  52 . On further advance of pin  58 , its conical tip  60  encounters the operating opening  56 . The pin  58 , because of the wedge effect of its conical tip  60 , moves the thrust plate  54  against the force of tension spring  50 , acting via lever  52 , until pin  58  has fully penetrated the operating opening  56  and is axially flush with the passage opening  40 . This position, with the fully inserted cassette  12 , is shown in  FIGS. 5, 6 ,  8 ,  10 ,  13  and  14 .  
         [0039]     In this end position, the thrust plate  54  has pushed slide  54  upward against the force of tension spring  50  via lever  52 , and the elongated hole  46  is also pushed upward on this account, so that the end  48  of parallel rod  36  can now move freely in elongated hole  46 . The arm  22 , with the advance head  18 , can now be lowered onto stack  10  of the cassette, freely pivotable under its own weight.  
         [0040]     If, during lowering of advance head  18 , its advance rollers  20  come in contact with the slope  16  and cassette  12 , the advance rollers  20  roll along this slope  16 , until they lie on the uppermost sheet of stack  10 . In this case, a bias of the springs, acting on the advance rollers  20  in advance had  18 , is produced.  
         [0041]     The process runs in reverse, when the cassette  12  is removed from the inserted position. During removal of cassette  12 , pin  58  is initially pulled out from the operating opening  56  of the thrust plate  54 . The thrust plate  54  is released and the tension spring  50  can pull the pusher  44  downward. The pusher  44  then engages on the end  48  of parallel rod  36 , pulls this end downward, so that the arm  22 , with advance head  18 , is raised. On further removal of the cassette  12 , the pin  58  is also removed from the passage opening  40  of slide  28 . Because of this, slide  28  is also released and the tension springs  52  can pull the slide and, with it, the arm  22  with advance head  18 , away from the slope  16 , so that the cassette  12  is fully released and can be removed unhampered from the receiving space.