Abstract:
A disk stacker system for delivering selectively inverted substrate assemblies into a receiving tray. By alternating inverted with non-inverted substrate assemblies or otherwise grouping inverted and non-inverted substrate assemblies, handling of folded printed material is made more efficient and packing of the folded printed material is made more dense and efficient. The disk stacker system operates by delivering selected substrate assemblies directly to the output tray and bypassing the disk stacker inverting apparatus and by delivering other substrate assemblies to the disk stacker apparatus for inversion prior to delivery to the output tray.

Description:
FIELD OF THE INVENTION  
         [0001]    The field of the invention is finishing operations for printed material finished into assemblies of substrates such as booklets, newspapers, or similar compiled sets of substrate sheets. More particularly, the field of the invention relates to finishing equipment for stacking booklets and other printed articles comprised of folded substrates in an optimally compressed manner, especially when such booklets or folded articles are printed with digital printing systems such as electrophotographic printers. Although the invention will operate with both folded and unfolded assemblies of substrates, the advantages of the invention are apparent when performing finishing operations upon folded substrate materials.  
         BACKGROUND AND SUMMARY  
         [0002]    very common form of printed matter is booklets comprised of folded sheets. Many such booklets are stapled, stitched, or otherwise bound along the fold and sometimes covered with a soft cover comprised of somewhat heavier substrate stock than the interior printed pages. Playbills, advertising booklets, mail order catalogues, many magazines, and many other printed articles are printed and bound in this manner. Other forms of printed material comprise assemblies of folded pages, or substrates, such as newspapers, which are folded but not bound.  
           [0003]    Referring to FIGS. 1 and 2, a problem common to such folded printed materials is that a bulge occurs proximate to the folded edge of the printed assembly. The fold results because molecules or fibers within printed substrates such as plastic and paper retain some resistance to the fold. The result is that when such folded assemblies of substrates are stacked vertically as shown in FIG. 1, the side  11  of the stack containing the folded edges typically rises significantly higher than the side  12  having unfolded edges. If the stack is not contained as in a box, then the scene exemplified by FIG. 2 is common. Most household members are probably familiar with the situation shown in FIG. 2 when attempting to stack used newspapers.  
           [0004]    One alternative to alleviate the problems shown in FIGS. 1 and 2 is shown in FIG. 3. In this solution, vertical stacks are avoided, and folded printed matter is partially overlaid on a planer surface such as a conveyor belt. Many newspaper publishing operations convey papers in this matter to their packaging and distribution operations. Of course, such planer surfaces occupy significant floor space and are impractical in most printing environments other than commercial print shops.  
           [0005]    It would be advantageous to have an apparatus and method for vertically stacking folded printed matter in a manner that avoids the uneven stacks shown in FIGS. 1 and 2. It would be further advantageous if such apparatus and method required a relatively small footprint and relatively inexpensive equipment.  
           [0006]    One aspect of the invention is a disk stacker system for selectively inverting substrate assemblies, comprising: a rotatable disk stacker having a slot for receiving a compiled assembly of substrates; a tray for receiving a plurality of substrate assemblies; and an apparatus for feeding the substrate assembly, said feeding apparatus having a first mode and a second mode wherein, in the first mode, said apparatus cooperates with the rotatable disk to feed the substrate assembly into the receiving slot of the rotatable disk stacker and, in the second mode, said apparatus feeds the substrate assembly to the tray without feeding the substrate assembly to the receiving slot of the rotatable disk stacker; wherein, in the first mode, after the substrate assembly is fed into the receiving slot of the rotatable disk stacker, the rotatable disk stacker rotates with the substrate assembly in its receiving slot and deposits the substrate assembly onto the tray in an inverted orientation; and wherein, in the second mode wherein the substrate assembly is fed to the tray without entering the receiving slot, the substrate assembly is delivered to the tray in an non-inverted orientation.  
           [0007]    Another aspect of the invention is a printer system for printing and compiling a substrate assembly, said printer comprising: a rotatable disk stacker having a slot for receiving a compiled assembly of substrates; a tray for receiving a plurality of substrate assemblies; and an apparatus for feeding the substrate assembly, said feeding apparatus having a first mode and a second mode wherein, in the first mode, said apparatus cooperates with the rotatable disk to feed the substrate assembly into the receiving slot of the rotatable disk stacker and, in the second mode, said apparatus feeds the substrate assembly to the tray without feeding the substrate assembly to the receiving slot of the rotatable disk stacker; wherein, in the first mode, after the substrate assembly is fed into the receiving slot of the rotatable disk stacker, the rotatable disk stacker rotates with the substrate assembly in its receiving slot and deposits the substrate assembly onto the tray in an inverted orientation; and wherein, in the second mode wherein the substrate assembly is fed to the tray without entering the receiving slot, the substrate assembly is delivered to the tray in an non-inverted orientation.  
           [0008]    Yet another aspect of the invention is a process for selectively inverting substrate assemblies, comprising: feeding a substrate assembly to a rotatable disk stacker system; selecting between a first and a second mode, wherein the first mode comprises feeding the substrate assembly into a receiving slot of the rotatable disk stacker and the second mode comprises feeding the substrate assembly to a tray without feeding the substrate assembly to the receiving slot of the rotatable disk stacker; and wherein the first mode further comprises rotating the rotatable disk stacker with the substrate assembly in its slot and depositing the substrate assembly onto the tray in an inverted orientation. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    [0009]FIG. 1 is a plane view of a stack of folded substrate assemblies stacked using apparatus of the prior art;  
         [0010]    [0010]FIG. 2 is a plane view of a disordered stack of folded substrate assemblies stacked using apparatus of the prior art;  
         [0011]    [0011]FIG. 3 is a plane view of an arrangement of folded substrate assemblies using apparatus of the prior art;  
         [0012]    [0012]FIG. 4 is a plane view of a stack of folded substrate assemblies stacked using the present invention;  
         [0013]    [0013]FIG. 5 is an elevated cross sectional view of one embodiment of the disk stacker system of the present invention when delivering a non-inverted substrate assembly to an output tray;  
         [0014]    [0014]FIG. 6 is an elevated cross sectional view of the embodiment shown in FIG. 5 when inserting a substrate assembly into an inverting disk stacker apparatus;  
         [0015]    [0015]FIG. 7 is a plane view of an alternate method of stacking folded substrate assemblies using the present invention;  
         [0016]    [0016]FIG. 8 is an elevated cross sectional view of a second embodiment of the present invention.  
     
    
     DESCRIPTION  
       [0017]    For a general understanding of the present invention, reference is made to the drawings. In the drawings, like reference numerals have been used throughout to designate identical elements.  
         [0018]    An exemplary system comprising one embodiment of the present invention is a multifunctional printer with an attached finisher apparatus comprising the present invention. Multifunctional printers are well known in the art and may comprise print engines based upon liquid or solid ink jet, electrostatography such as electrophotography, and other imaging devices. The general principles of electrophotographic imaging are well known to many skilled in the art. Generally, the process of electrophotographic reproduction is initiated by substantially uniformly charging a photoreceptive member, followed by exposing a light image of an original document thereon. Exposing the charged photoreceptive member to a light image discharges a photoconductive surface layer in areas corresponding to non-image areas in the original document, while maintaining the charge on image areas for creating an electrostatic latent image of the original document on the photoreceptive member. This latent image is subsequently developed into a visible image by a process in which a charged developing material is deposited onto the photoconductive surface layer, such that the developing material is attracted to the charged image areas on the photoreceptive member. Thereafter, the developing material is transferred from the photoreceptive member to a copy sheet or some other image support substrate to which the image may be permanently affixed for producing a reproduction of the original document. In a final step in the process, the photoconductive surface layer of the photoreceptive member is cleaned to remove any residual developing material therefrom, in preparation for successive imaging cycles.  
         [0019]    The above described electrophotographic reproduction process is well known and is useful for both digital copying and printing as well as for light lens copying from an original. In many of these applications, the process described above operates to form a latent image on an imaging member by discharge of the charge in locations in which photons from a lens, laser, or LED strike the photoreceptor. Such printing processes typically develop toner on the discharged area, known as DAD, or “write black” systems. Light lens generated image systems typically develop toner on the charged areas, known as CAD, or “write white” systems. Embodiments of the present invention apply to both DAD and CAD systems. Since electrophotographic imaging technology is so well known, further description is not necessary. See, for reference, for example, U.S. Pat. No. 6,069,624 issued to Dash, et al. and U.S. Pat. No. 5,687,297 issued to Coonan et al., both of which are hereby incorporated herein by reference.  
         [0020]    With reference now to FIG. 4, a desired method of stacking folded assemblies of printed substrates is shown. This neat stack of printed substrates may be the output of a multifunctional printer as described above or may be the output of any other print method, including without limitation, offset lithography, silk screen, liquid or solid ink jet, etc. Also, the output shown in FIG. 4 may be received in the schematically shown bin directly from the printer or press or may arrive from any variety of intermediate finishing equipment. The result of the invention, as shown in FIG. 4, is a neat stack of folded assemblies of printed substrates in which the folded edges labeled A alternate with the unfolded edges B.  
         [0021]    One embodiment of the present invention that accomplishes the result shown in FIG. 4 is shown in FIG. 5. This embodiment of the invention borrows from the two decades of experience with single sheet disk inverter apparatus. Such experience is exemplified by U.S. Pat. No. 4,431,177, issued to J. Beery et al., U.S. Pat. No. 5,065,996 issued to McGraw et al., U.S. Pat. No. 5,409,202, issued to Naramore et al., U.S. Pat. No. 5,409,201, issued to Naramore et al., and U.S. Pat. No. 5,551,681, issued to Ferrara. As noted in Ferrara, “conventional disk stackers only invert one single sheet at a time” U.S. Pat. No. 5,551,681, column 1, lines 54-56. Ferrara is the exception and describes a disk stacker that compiles a stack of sheets through use of a disk within a disk arrangement. Ferrara and other disk stackers provide for stapling and other finishing processes after copy substrates enter the disk stacker. See FIG. 11 of Ferrarra, U.S. Pat. No. 5,551,681. See also, U.S. Pat. No. 5,409,202, issued to Naramore et al. Each of these patents are hereby incorporated herein by reference in their entirety. Each of the cited patents and others in the prior art provide for disk stackers that invert and stack sheets in preparation for finishing operations of the compiled stack. None provide for inverting and stacking of assemblies of sheets that already have been finished.  
         [0022]    Referring to FIG. 5, folded substrate stacker system  20  is shown. Beginning from left to right, folded assembly  15  approaches stacker system  20  after having been folded and otherwise finished. Such finishing may include binding by staples, glue, or other binding means or such finishing may simply comprise folding operations. Of course, it is apparent that system  20  will also work with unfolded substrate assemblies, yet the primary purpose for which system  20  is expected to be used is in relation to folded assemblies of substrates. Upon entering the mouth of channel  23 , substrate assembly  15  is gripped and pushed forward by drive wheels  21  and  22 . At least one of drive wheels  21  and  22  are slidably held in place in order to adjust to varying thicknesses between different substrate assemblies  15  and, optionally, between the leading and trailing edges of each substrate assembly  15 . Such slidable mounting of one or both wheels  21  and  22  may be accomplished by mounting the applicable wheel within a slide track and attaching biasing springs to urge the applicable wheel toward channel  23 . For wheels such as  21  which are above channel  23 , gravity may provide sufficient biasing.  
         [0023]    As shown in FIG. 5, it is anticipated that most substrate assemblies will enter channel  23  with folded edge first. This arrangement inhibits outer sheets of substrate assembly  15  from getting wrinkled, folded, or otherwise damaged by the apparatus within system  20 . This arrangement also minimizes the possibility of a jam occurring because one of more sheets become caught in the apparatus. It is also possible, however, to operate system  20  by having substrate assembly  15  lead with its unbound and unfolded edge.  
         [0024]    After drive wheels  21  and  22  urge substrate assembly  15  further into channel  23 , leading edge sensor  24  detects the leading edge of substrate assembly  15 . Sensor  24  may comprise any number of well known detector technologies, including a simple assembly of an LED light source and a light detector spaced apart on opposite sides of channel  23 . As substrate assembly  15  passes sensor  24 , it blocks light from the light detector. Sensor  24  then sends a positive leading edge detection signal to the controller  29  for system  20 . In this manner, sequence timing within system  20  can be maintained and parts activated to achieve the desired result. As shown in FIG. 5, substrate assembly  15  passes sensor  24  and next encounters drive wheels  25  and  26 . These drive wheels function much like drive wheels  21  and  22 , and the same or similar motor apparatus, mounting, and biasing may be used for drive wheels  25  and  26  as used for  21  and  22 .  
         [0025]    In FIG. 5, substrate assembly  16  has preceded assembly substrate  15  down channel  23  and is shown being driven, folded-edge first, into bin  27 . Bin  27  is shown as a box having left and right sides but may be a simple tray for receiving the substrate assembly. Disk stacker  30  is shown in its by-pass position. In this position, disk stacker  30  has been rotated such that its gripping finger  33  is turned away from channel  23  and away from substrate assembly  16 . Non-gripping surface  32  of disk stacker  30  is turned toward channel  23  and provides a rounded surface, along with drive wheel  26 , for guiding substrate assembly  16  toward and then out of channel mouth  28  without inversion. The result is that substrate assembly  16  falls into bin  27  oriented with its bound or folded edge removed away from system  20 .  
         [0026]    Referring to FIG. 6, operation of disk stacker  30  is shown. In response from signals from the system controller, disk stacker  30  has been rotated such that finger  33  blocks channel mouth  28 . As drive wheels urge substrate assembly  15  forward, finger  33  diverts the leading edge of such substrate assembly into slot  31  of disk stacker  30 . Substrate assembly  15  is then urged forward into slot  31  until its leading edge contacts stop  34 . As is conventional with disk stackers, sensors detect when substrate assembly  15  makes contact with stop  34 , and disk stacker  30  is then rotated back to its starting position shown in FIG. 5. Such sensors are conventional in the art. Among the alternatives are pressure sensors placed on stop  34  itself or release mechanisms that engage disk stacker  30  once continued drive motion by drive wheels  25  and  26  begin forcing rotation of disk stacker  30  after substrate assembly  15  abuts stop  34 . A method for removing substrate assembly  15  from finger  33  is for substrate assembly  15  to encounter a stop as disk stacker  30  continues to rotate. Regardless of the method to begin rotation of disk assembly  30  or to free substrate assemblies from finger  33 , the result is that substrate assembly  15  is flipped into an inverted position onto the top of the stack in bin  27 . This inversion and stacking result due to rotation of a disk stacker is well known to those skilled in the relevant disk stacker arts. The ability to perform this operation upon substrate assemblies rather than single sheets is novel as is the ability to alternate inversion and non-inversion operations. The stack of substrate assemblies that results is easier to handle and takes less volume.  
         [0027]    Turning to FIG. 7, another variety of stacking is shown. In this embodiment, the same level and efficient stack of substrate assemblies has been achieved. Instead of alternating the inversion operation, a first bundle  41  of substrate assemblies has been placed in bin  27  in an inverted orientation and a second bundle  42  has been stacked on top of bundle  41  in an un-inverted orientation. It is believed that this arrangement may often facilitate future handling of the substrate assemblies since an entire bundle can be lifted out of a bin or box in the same orientation, and a user need not reorient each compilation for handling. For instance, playbills arranged in this manner may be easier for ushers to handle than a stack in which each playbill is placed in an alternating orientation.  
         [0028]    The controller  29  for stacker system  30  controls whether substrate assemblies are stacked in alternating copies, alternating groups or any other arrangement. In the event that a user desires all substrate assemblies to be loaded into bin  27  with all cover pages up or all cover pages down, then the controller  29  may coordinate with a printer controller (not shown) such that substrate assemblies such as  15  and  16  are printed cover page up and cover page down in alternating fashion that corresponds to the manner in which each such compilation will be stacked in bin  27 .  
         [0029]    Referring now to FIG. 8, a disk stacker system  50  is shown that is capable of higher through put speeds than the disk stacker system  30  shown in FIGS. 5 and 6. In this system  50 , disk stacker  60  has two sets of fingers,  63  and  64 , located on opposing sides of disk  60 .. Drive wheels  21 ,  22 ,  25 , and  26  serve the same function as described in relation to FIGS. 5 and 6 as does bin  27 . In the middle of channel  23 , however, is pivotally mounted diverter gate  68 , shown in both of its operable positions. Such diverter gates are well known to those skilled in the relevant arts. See, for example, U.S. Pat. No. 4,712,785 issued to Stemmle; U.S. Pat. No. 5,303,017 issued to Smith; and U.S. Pat. No. 5,065,996, issued to McGraw et al. In FIG. 8, substrate assembly  17  has been directed down channel  23  toward disk stacker  60 . Disk stacker  60  operates similarly to disk stacker  30  shown in FIGS. 5 and 6, and operates to invert and stack substrate assembly  17  into bin  27 . Once substrate assembly  17  has passed diverter gate  68 , controller  29  directs a pivot mechanism to switch diverter gate  68  to its alternate position. Substrate assembly  18  will be diverted into alternate channel  69 . Alternate channel  69  carries substrate assembly  18  around disk stacker  60  and toward drive wheels  66  and  67 . Drive wheels  66  and  67  urge substrate assembly  18  into bin  27 . Pivotally mounted bail wire  65  is positioned to assist substrate assembly  18  to fall into bin  27  in an un-inverted, controlled fashion.  
         [0030]    The stacking result of the apparatus in FIG. 8 is the same as achievable with the system shown in FIGS. 5 and 6. One skilled in the art will recognize that some of the features in FIGS. 5 and 6 can be interchanged with features shown in FIG. 8 and vice versa. Specifically, a double set of fingers, a diverter gate, an alternate channel, and a bail wire guide may individually be integrated into stacker system  20  shown in FIGS. 5 and 6. Similarly, a stacker disk with a single finger and a single channel with or without a diverter gate can be integrated into stacker system  50  shown in FIG. 8. Other variations are also possible.  
         [0031]    In sum, an improved disk stacker system has been disclosed that provides for inversion of substrates, especially folded substrates such as booklets and newspapers. When such inversion is alternated between compiled sets or between groups of compiled sets, then stacking efficiency and order are greatly improved over the prior art.  
         [0032]    While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.