Abstract:
A hand-held device for shredding paper comprising a pair of rotary cutting wheels disposed within a housing between an inlet slot and an outlet slot. A motor is positioned in the handle to drive the cutting wheels through a gear assembly. One wheel serves as a drive wheel, which is coupled directly to the gear assembly, and the other wheel serves as an idler, driven from a spur gear attached to the drive wheel at the end opposite a gear case. Paper sheets are fed into the inlet slot and pulled between the wheels. Wheels are comprised of a stack of alternating discs of a large and small radius, and staggered so as to allow the two wheels to be interleaved while rotating in opposite (clockwise and counterclockwise) directions and maintain clearance. Large discs have a frictional edge to grab and feed the paper into the intersection of the wheels, tearing the paper into strips and forcing the strips into the outlet slot. A battery compartment in the handle contains the batteries for energizing the motor.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a continuation of International Application No. PCT/US03/023476, filed Jul. 28, 2003, entitled “Portable Hand-Held Paper Shredder.” That application claimed the benefit of U.S. Provisional Patent Application Ser. No. 60/398,755, filed Jul. 26, 2002, under the same title. 
     
    
     FIELD OF THE INVENTION  
       [0002]     This invention relates to paper shredders, and more particularly, to battery-powered, hand-held, portable paper shredders.  
       BACKGROUND OF THE INVENTION  
       [0003]     Due to recent increased incidents of information theft, individuals, as much as businesses, feel the need to destroy financial and personal records in order to protect such confidential information. The security purposes served by shredding documents include prevention of identity theft, credit card and bank fraud, and even espionage.  
         [0004]     Electric paper shredders were invented in the 1930s, but for many years, their cost and bulk made them accessible only to corporations and government agencies. In the mid-1980s, paper shredders became more affordable and were designed on a smaller scale to accommodate small office and individual users. These personal shredders were still not economical, though, until in the mid-1990s, prices of paper shredders dropped further, into the “affordable” range. At about that same time, identity theft became common, and the use of personal shredders increased dramatically.  
         [0005]     Institutional and even criminal use of paper shredders to destroy sensitive documents and incriminating documentary evidence of wrongdoing has brought the paper shredder even more into public focus when large companies have tried to hide wrongdoing by feverishly shredding documents while a government fraud investigation was underway or about to begin.  
         [0006]     When individuals shred their sensitive documents and throw the shredding out with their other garbage, there are orange peels and coffee grounds mixed in with the shreddings. Identity thieves are thus frustrated in their efforts to piece together documents that have been shredded.  
         [0007]     Therefore, there exists a need for a lightweight, hand-held, battery-powered paper shredder that is convenient to use and compact for storage in a desk drawer or on a desktop.  
       SUMMARY OF THE INVENTION  
       [0008]     A hand-held device for shredding paper comprises a housing having a handle portion and a shredding portion. The shredding portion has an elongated inlet aperture and an elongated outlet aperture, with a pair of rotating wheel assemblies disposed intermediate the inlet and outlet apertures. Each wheel assembly has means integral to the assembly for frictionally engaging one or more sheets of paper. The handle contains a drive means for imparting rotational motion to the rotating wheel assemblies. The rotating wheel assemblies are each comprised of a plurality of wheels, comprising cutting wheels and spacer wheels in axially alternating positions along a rod. The cutting wheels and spacer wheels are staggered relative to the opposing wheel assemblies to permit cutting wheels to interleave between wheel assemblies and to maintain clearance to permit cooperating rotation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a perspective view of a hand-held paper shredder;  
         [0010]      FIG. 2  is an elevational view taken along the lines  2 - 2  in  FIG. 1 ;  
         [0011]      FIG. 3  is a cross-sectional view taken along the lines  3 - 3  in  FIG. 1 ;  
         [0012]      FIG. 4  is an exploded view of the hand-held paper shredder;  
         [0013]      FIG. 5  is an exploded view of the gearbox assembly;  
         [0014]      FIG. 6  is a cross-sectional view of the gearbox assembly;  
         [0015]      FIG. 7  is a fragmentary sectional view of the motor and gearbox assembly connection to the shredder wheels;  
         [0016]      FIG. 8  is a perspective rear view of the gear housing;  
         [0017]      FIG. 9  is a plan view of the coupling/grease retainer;  
         [0018]      FIG. 10  is a side view of the coupling/grease retainer;  
         [0019]      FIG. 11  is a plan view of the top portion of the housing showing a modified slot configuration;  
         [0020]      FIG. 12  is a sectional view taken along the lines  12 - 12  in  FIG. 11 ;  
         [0021]      FIG. 13  is a perspective view of the interior of the top housing;  
         [0022]      FIG. 14  is a perspective view of the interior of the bottom housing;  
         [0023]      FIG. 15  is a detail of the area designated as  15  in  FIG. 14 ; and  
         [0024]      FIG. 16  is an alternate arrangement of a coupling retainer. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     Referring first to  FIG. 1 , a hand-held paper shredder is generally designated as  10 . Shredder  10  includes a bottom shell portion  12  and two interlocking top shell portions  14 ,  16 . The first top shell portion  14  includes a first elongated aperture  18  into which one or more sheets of paper may be inserted for shredding. A second elongated aperture  18   a  (not shown) is disposed opposite first elongated aperture in a battery compartment cover  30 . Second top shell portion  16  includes a slideable, spring-maintained, momentary reversing switch  20 . Switch  20  may also be a pushbutton type switch. A raised collar  21  surrounds the switch  20 . The raised collar  21  projects upward slightly beyond the raised portion of switch  20 , so that the switch  20  will not be accidentally operable when laid on a surface with the switch facing down. Battery compartment cover  30  attaches to bottom shell portion  12  to conceal the batteries within. The battery compartment cover  30  is releasable by depressing a release tab  22  and pulling away from the bottom shell portion  12 .  
         [0026]     Referring next to  FIG. 2 , an end view of the shredder  10  is shown. First top shell portion  14  is attached to bottom shell portion  12  and battery compartment cover  30  attaches to bottom shell portion  12 . The corrugated release tab  22  is disposed centrally of the battery compartment cover  30 . Aperture  18  is shown at the apex of the curvature of first top shell portion  14 .  
         [0027]     Referring next to  FIG. 3 , a cross-sectional view through the shredder shows two of the four batteries  26 ,  28  situated in the battery compartment adjacent to shredder wheel assemblies  38 ,  40 . Cutter wheels  44  define the outermost perimeter of large spacer wheels  42 . Small spacer wheels  46  are juxtaposed with the large spacer wheels  42  so as to permit the adjacent shredder wheel assemblies  38 ,  40  to interleave in a partially overlapping cross section, while maintaining clearance to rotate freely on the wheel assemblies  38 ,  40 .  
         [0028]     The adjacent shredder wheel assemblies  38 ,  40  are spaced apart a distance less than the radius of the large spacer wheels  42  and greater than the radius of small spacer wheels  46 .  
         [0029]     Referring next to  FIGS. 4, 5 , and  6 , an exploded view illustrates the order in which the parts are assembled. Four batteries  26 ,  27 ,  28 ,  29  are disposed on the bottom portion of paper shredder  10  and enclosed when battery compartment cover  30  is attached to the bottom shell portion  12 . The bottom shell portion  12  provides a support frame for the rotating parts of the shredder  10 . Also, teeth  36  are positioned adjacent to shredder wheel assemblies  38 ,  40  at the junction of the two shredder assemblies  38 ,  40  to scrape the surfaces of wheels  42 ,  46  as they rotate. The teeth  36  scrape away any shreddings that cling to the wheel surfaces  42 ,  46 , and direct them into the second elongated aperture to be discharged to prevent paper shreds from clogging in the housing and restricting the rotational movement of first and second shredder wheel assemblies  38 ,  40 .  
         [0030]     A small DC electric motor  50  is disposed in the end of handle or bottom shell portion  12  beneath second top shell portion  16 . A shaft  52  of motor  50  is inserted into a drive shaft  54  having a knurled, straight-molded end portion. Drive shaft  54  is inserted into a gearbox subassembly  60  to couple the motor  50  with the gearbox subassembly. The gearbox subassembly  60  has mounting frame portions  62  on either side of the drive axis in order to fasten the gearbox subassembly  60  to the bottom shell portion  12 . A pair of screws  68  is threaded into corresponding mounting stands  69  to secure the motor  50  and gearbox subassembly  60 . The shredder wheel is the drive shaft and is connected to a drive shaft extension  100 . The first shredder wheel  64  is the drive wheel, which is coupled directly to gearbox subassembly  60  through drive shaft  100  at one end. At the opposite end, the first shredder wheel is coupled to a first spur gear  70 , which is engaged with a second spur gear  72 . Second spur gear  72  is, in turn, coupled to the second shredder wheel, which is also referred to as an idler, which rotates when a drive shredder wheel  64  rotates through coupling with the motor  50 . When the driver first shredder wheel  38  (also referred to as the “drive wheel”) is rotated in a counterclockwise direction, first spur gear  70  drives second spur gear  72 . Spur gear  72  is attached to second (or “idler”) shredder wheel  40 . Spur gear  72  simultaneously drives idler shredder wheel assembly  40  in a clockwise direction. A junction  48  of the idler  40  and drive  38  wheel assemblies is positioned directly below and central of elongated aperture  18 , so as to urge a sheet of paper in the downward direction toward a battery compartment cover aperture  31  and out of the shredder. Junction  48  is non-linear, forming a square-wave profile, causing the sheets of paper, when introduced into the elongated aperture  18 , to be pulled in opposite directions at each segment along the square wave junction  48 . Thus, the paper is shredded into narrow strips corresponding approximately to the width of the individual spacer wheels  42 ,  46  of the assemblies,  38 ,  40 .  
         [0031]     The bottom shell portion  12  is attached to the first top shell portion  14  by means of two pairs of screws  32 ,  34  projecting through the mounting stands  69  and into receptacles (not shown) on first top shell portion  14 .  
         [0032]     The rocker switch  20  includes contact portions  104 , an upper contact portion  106 , a lower contact portion  110 , and an insulator sheet  108  disposed between upper and lower contact portions  106 ,  110 .  
         [0033]      FIG. 5  illustrates an exploded view of the gearbox assembly, generally designated as  60 . A retainer disc  82  acts as a grease seal between the face of the motor  50  and the gearbox assembly  60 . An aperture  116  in disc  82  is adapted to receive the end of the drive shaft  54  into engagement with three planetary gears  84 ,  86 ,  88  arranged concentrically on a first reduction pinion  90 . Apertures  85 ,  87 ,  89  and planetary gears  84 ,  86 ,  88  are attached to and rotate about three raised portions  112  (only one shown), which rotate within a gearbox housing  80  to turn a pinion gear  91 . Pinion gear  91  engages a second set of planetary gears  92 ,  94 ,  96  also meshing concentrically, so as to rotate a second reduction pinion  98 . The planetary gears  92 ,  94 ,  96  are coupled to second reduction pinion  98  by a raised portion  114 . When planetary gears  92 ,  94 ,  96  rotate, second reduction pinion  98 , in turn, rotates, causing the drive shaft extension  100  to turn the shredder wheel assemblies  38 ,  40 . Preferably, a bushing  102  is inserted in the end of gearbox housing  80  to absorb wear caused by rotation.  
         [0034]      FIG. 6  is a center cross-sectional view of the gearbox subassembly  60 , showing the arrangement of the gearbox subassembly in the assembled state.  
         [0035]     Referring next to  FIG. 7 , a reverse angle of the gearbox housing is shown illustrating interior teeth  58 , which cooperate with the planetary gears to cause rotation of the first and second pinions  90 ,  98  and to achieve the desired speed reduction between the motor  50  and shredder wheel assemblies  38 ,  40 .  
         [0036]     Referring next to  FIGS. 9 and 10 , an alternate arrangement for the retainer disc is shown. A retainer disc  182  includes a cylindrical hub  190  mounted on a flange  184 . Web portion  186  connects hub  190  to flange  184 , to provide stabilization and reinforcement. The retainer has a hollow axial bore  188 , into which the motor shaft extends. A pair of alignment tabs  192  interlock with complementary recesses (not shown) in the face of the motor, for preventing rotation of the retainer disc relative to the motor shaft. The shaft fits snugly inside the bore  188  to properly align the motor shaft with the gear train. A pair of screw holes  195  are drilled through the retainer disc for fastening the disc to the face of the motor.  
         [0037]      FIG. 16  shows yet another alternative arrangement for the retainer disc. In this arrangement, the retainer disc  182  includes a plurality of wing portions  194  as supplementary alignment means between the motor and gearbox. In the embodiment shown in  FIG. 16 , there are four wings spaced at 90° intervals about the radius. Equidistantly-spaced, more or less, wings may be employed.  
         [0038]     Referring next to  FIGS. 11-15 , the top housing  200  has a modified paper feed slot  202 . At either end of the slot  202  is a bulbous opening  204  that tapers to the narrowed feed slot  202 . This arrangement prevents the user from feeding paper in excess of the thickness of which the shredder can cut at one time, thereby preventing clogging and jamming. In the preferred embodiment, approximately six to eight sheets of standard weight copy or bond paper will pass easily through the slot  202  for shredding, although by varying the width of the slot and the power rating of the motor, more or less paper can be processed through the shredder. The openings  204  allow the slot  202  to flex slightly, and provide a path for excess material to flow through at the ends, as there is a tendency for paper shreds and fine particles to collect near the ends of the slot  202 .  
         [0039]     A series of teeth or stripper portions  210  are shown forming a square wave profile on the internal side of the top housing. Stripper portions  210  are positioned adjacent to shredder wheel assemblies on top and bottom sides. Stripper portions are disposed beneath the top side of the housing, in order to strip away shreddings when the motor rotates in the reverse direction. Stripper portions provide an alternate means to clean and prevent jamming of the shredder wheel assemblies, by stripping paper shreddings from the cutting wheels while they rotate. Switch  20  (shown in  FIG. 7 ) is a reversing-type switch capable of switching DC power to the motor in alternating polarity to selectively drive the motor in either clockwise or counterclockwise rotation. When an excessive amount of paper is fed into the feed slot  202 , reversing the direction of the motor clears the paper flow path of the shredder by forcing it back out of the slot  202 .  
         [0040]     Backup pins  212  are metal or plastic pins that serve as travel limits for the shredder wheel assemblies when the rollers flex and separate from an excess amount of paper in the slot. When the thickness of the sheet or sheets becomes too great, the shredder wheel assemblies will try to separate, but will be prevented by the pins  212  from separating any further. The pressure applied against the pins provides additional traction to the paper passing through the slot to aid in pulling the paper through, and ensures that no paper passes through uncut, due to separation between the shredder wheel assemblies (not shown). Pins  212  are retained in place by a pair of hollow bosses  214 , having hollow cavities to receive the pins snugly, and to prevent the pins from moving laterally. The opposite end of pins  212  are captured by a pair of semi-circular receptors  216  molded into the bottom housing  218  opposite the bosses  214  in the top housing portion. The semi-circular receptors  216  prevent the pins from moving in the direction of separation, and leaves them free to move inward to release lateral force from the receptors  216  when no pressure is being applied by the shredder wheel assemblies.  
         [0041]     The momentary-contact switch on the handle also provides a means for test operation that may be used in the original packaging. The momentary operation of the switch permits the user to operate the device  10  while still wrapped in protective packaging. A transparent thin plastic barrier (not shown) is molded around a portion of the device  10  and adhesively or mechanically attached to a backing sheet of cardboard (also not shown) with the device secured between the plastic barrier and the cardboard. The plastic is pliable so that the pushbutton on the switch may be urged forward to the “ON” position, to turn on the device while on the store shelf. The switch is returned to the “OFF” position when released, thereby avoiding unintended drainage of the batteries in the packages. This advantageous feature invites people to test operate the device.  
         [0042]     According to the provisions of the patent statutes, we have explained the principle, preferred construction, and mode of operation of the invention and have illustrated and described what we now consider to represent its best embodiments. However, it should be understood that within the scope of the appended claims and the foregoing description, the invention may be practiced otherwise than specifically illustrated and described.