Abstract:
An electric pencil sharpener is provided. This pencil sharpener includes a motor, a cutter assembly, mechanical means for operatively connecting the motor to the cutter assembly, and a housing. The cutter assembly includes a rotating carrier with at least two helical cutters mounted on the carrier. The mechanical means for operatively connecting the motor to the cutter assembly further includes a first gear assembly mechanically coupled to the motor; a second gear assembly mechanically coupled to the first gear assembly and to the cutter assembly; a gearbox for supporting the first and second gear assemblies; and a cover for enclosing the first gear assembly. The housing further includes a canopy and a base positioned underneath the canopy.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This patent application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/269,853 filed on Jun. 30, 2009 and entitled “Sharpener with Noise Reducing Features”, U.S. Provisional Patent Application Ser. No. 61/221,221 filed on Jun. 29, 2009 and entitled “Sharpener with Autostop Feature”, and U.S. Non-Provisional patent application Ser. No. 12/826,041 filed on Jun. 29, 2010 and entitled “Pencil Sharpener with Autostop Feature”, the disclosures of which are hereby incorporated by reference herein in their entirety and made part of the present U.S. utility patent application for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The described invention relates in general to an electric pencil sharpener and more specifically to an electric pencil sharpener that includes a variety of features for reducing the noise typically generated by such devices. 
         [0003]    Electric pencil sharpeners are very common devices in modern offices, schools, and places of business. To use an electric pencil sharpener, the user typically inserts a pencil in need of sharpening into and through an opening at one end of the sharpener. Once inserted, the pencil activates a motor which drives one or more rotating sharpening blades that remove the wood casing from around the piece of lead embedded within the body of the pencil. While generally quite effective at sharpening pencils, electric pencil sharpeners often tend to generate a significant amount of noise during operation. This noise can be very disruptive and may even result in such pencil sharpeners being banned from particular environments. Therefore, there is an ongoing need for a reliable electric pencil sharpener that quietly and effectively sharpens pencils or similar items. 
       SUMMARY OF THE INVENTION 
       [0004]    The following provides a summary of certain exemplary embodiments of the present invention. This summary is not an extensive overview and is not intended to identify key or critical aspects or elements of the present invention or to delineate its scope. 
         [0005]    In accordance with one aspect of the present invention, an electric pencil sharpener having noise reducing features is provided. This pencil sharpener includes a motor, a cutter assembly, mechanical means for operatively connecting the motor to the cutter assembly, and a housing for containing the motor, the cutter assembly, and the mechanical means for operatively connecting the motor to the cutter assembly. The cutter assembly further includes a rotating carrier, wherein the carrier further includes a carrier shaft; at least two helical cutters mounted on the carrier, wherein the helical cutters define a conical cavity therebetween; and a barrel positioned at the large end of the conical cavity, wherein the barrel includes a bore formed therein for receiving a pencil. The mechanical means for operatively connecting the motor to the cutter assembly further includes a first gear assembly mechanically coupled to the motor; a second gear assembly mechanically coupled to the first gear assembly and to the cutter assembly; a gearbox for supporting the first and second gear assemblies; and a cover for enclosing the first gear assembly. The housing further includes a canopy, wherein the canopy further includes an aperture in the front portion thereof, and wherein the aperture is adapted to receive a pencil; and a base positioned underneath the canopy, wherein the base further includes at least one mount formed thereon, and wherein the at least one mount is adapted to receive the bottom portion of the gearbox. 
         [0006]    In accordance with another aspect of the present invention, an electric pencil sharpener having additional noise reducing features is provided. This pencil sharpener includes a motor, a cutter assembly, mechanical means for operatively connecting the motor to the cutter assembly, a housing for containing the motor, the cutter assembly, and the mechanical means for operatively connecting the motor to the cutter assembly, and at least one vibration dampening device. The motor is a DC motor having a voltage of about 120V. The cutter assembly further includes a rotating carrier, wherein the carrier further includes a carrier shaft; at least two helical cutters mounted on the carrier, wherein the helical cutters define a conical cavity therebetween; and a barrel positioned at the large end of the conical cavity, wherein the barrel includes a bore formed therein for receiving a pencil. The mechanical means for operatively connecting the motor to the cutter assembly further includes a first gear assembly mechanically coupled to the motor; a second gear assembly mechanically coupled to the first gear assembly and to the cutter assembly; a gearbox for supporting the first and second gear assemblies; and a cover for enclosing the first gear assembly. The housing further includes a canopy, wherein the canopy further includes an aperture in the front portion thereof, and wherein the aperture is adapted to receive a pencil; and a base positioned underneath the canopy, wherein the base further includes at least one mount formed thereon, and wherein the at least one mount is adapted to receive the bottom portion of the gearbox. The at least one vibration dampening device is positioned between the bottom of the gearbox and the top of the at least one mount formed on the base portion of the housing. 
         [0007]    In yet another aspect of this invention, an electric pencil sharpener having still more noise reducing features is provided. This pencil sharpener includes a motor, a cutter assembly, mechanical means for operatively connecting the motor to the cutter assembly, a housing for containing the motor, the cutter assembly, and the mechanical means for operatively connecting the motor to the cutter assembly, at least one vibration dampening device, and a plurality of feet attached to the base for supporting the pencil sharpener above a surface upon which it has been placed. The motor is a DC motor having a voltage of at least 120V. The cutter assembly further includes a rotating carrier, wherein the carrier further includes a carrier shaft; at least two helical cutters mounted on the carrier, wherein the helical cutters define a conical cavity therebetween; and a barrel positioned at the large end of the conical cavity, wherein the barrel includes a bore formed therein for receiving a pencil. The mechanical means for operatively connecting the motor to the cutter assembly further includes a first gear assembly mechanically coupled to the motor; a second gear assembly mechanically coupled to the first gear assembly and to the cutter assembly; a metal gearbox for supporting the first and second gear assemblies; and a cover for enclosing the first gear assembly. The housing further includes a canopy, wherein the canopy further includes an aperture in the front portion thereof, and wherein the aperture is adapted to receive a pencil; and a base positioned underneath the canopy, wherein the base further includes at least one mount formed thereon, and wherein the at least one mount is adapted to receive the bottom portion of the gearbox. The at least one vibration dampening device is positioned between the bottom of the gearbox and the top of the at least one mount formed on the base portion of the housing. The feet are suction cup-shaped elastomeric devices that are inserted into the base. 
         [0008]    Additional features and aspects of the present invention will become apparent to those of ordinary skill in the art upon reading and understanding the following detailed description of the exemplary embodiments. As will be appreciated by the skilled artisan, further embodiments of the invention are possible without departing from the scope and spirit of the invention. Accordingly, the drawings and associated descriptions are to be regarded as illustrative and not restrictive in nature. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying drawings, which are incorporated into and form a part of the specification, schematically illustrate one or more exemplary embodiments of the invention and, together with the general description given above and detailed description given below, serve to explain the principles of the invention, and wherein: 
           [0010]      FIG. 1  is an exploded, perspective view of an electric pencil sharpener in accordance with an exemplary embodiment of the present invention; 
           [0011]      FIG. 2  is a right side section view of the pencil sharpener of  FIG. 1  at the middle of the sharpener; 
           [0012]      FIG. 3  is a right side section view of the pencil sharpener of  FIG. 1  at the middle of the right gearbox mount; 
           [0013]      FIG. 4  is a perspective view of the exterior of the pencil sharpener of  FIG. 1 ; 
           [0014]      FIG. 5  is a side view of the exterior of the pencil sharpener of  FIG. 1 ; 
           [0015]      FIG. 6  is a front view of the exterior of the pencil sharpener of  FIG. 1 ; 
           [0016]      FIG. 7  is a top view of the exterior of the pencil sharpener of  FIG. 1 ; and 
           [0017]      FIG. 8  is a bottom view of the exterior of the pencil sharpener of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Exemplary embodiments of the present invention are now described with reference to the Figures. Reference numerals are used throughout the detailed description to refer to the various elements and structures. In other instances, well-known structures and devices may be shown in block diagram form for purposes of simplifying the description. Although the following detailed description contains many specifics for the purposes of illustration, a person of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention. 
         [0019]    The present invention relates to a quiet electric sharpener for pencils and the like. With reference now to the Figures, one or more specific embodiments of this invention shall be described in greater detail.  FIGS. 1-8  provide various views illustrative views of an exemplary embodiment of a quiet pencil sharpener in accordance with the present invention. As best shown in  FIGS. 1-3 , pencil sharpener  10  includes a multi-sectional housing that further includes top enclosure  20  having an aperture formed in the front portion thereof for receiving a pencil. A circular trim piece  24  is inserted into aperture  22 . Base  26  supports top enclosure  20  and further includes mounts  28 , which are adapted to receive the bottom portion of gearbox  58 , as well as port  30 , which is adapted to receive power cord  80 . A plurality of elastomeric supports or “feet”  32  are inserted into the bottom of base  26  and serve both to support pencil sharpener  10  above a surface on which it is sitting and to isolate pencil sharpener  10  from such a surface for the purpose of reducing any vibrations created during operation of the sharpener. Shavings receptacle  34  is positioned on the front portion of base  26  and may be removed to discard any shavings generated by the sharpening process. In the embodiment shown in the Figures, a piece of trim  36  is attached to the top edge of shavings receptacle  34 . 
         [0020]    As best shown in  FIGS. 1-3  the sharpening and drive train portions of pencil sharpener  10  include actuation switch  40 , which activates motor  76  when a pencil is inserted into sharpener  10 . Bracket  42 , which is attached to gearbox  58 , and ring  44 , which is seated within bracket  42 , support cutter assembly  46 . Cutter assembly  46  includes barrel  50 , which further includes a bore formed therein, two helical cutters  48 , and cutter carrier  52 , which further includes a shaft formed on one end thereof. Helical cutters  48  are mounted opposite one another on cutter carrier  52 , each at an angle so to form a conical cavity therebetween for receiving the tip of a pencil in need of sharpening. The drive train of pencil sharpener  10  includes a first gear assembly, which is mechanically coupled to motor  76 , and a second gear assembly, which is mechanically coupled to the first gear assembly. Both gear assemblies are supported by gearbox  58 . In the exemplary embodiment shown in the Figures, the first gear assembly includes pinion gear  70 , carrier gear  66 , and third gear  68  operatively positioned between pinion gear  70  and carrier gear  66 . The second gear assembly includes cutter drive gear  54 , which is operatively connected to cutter assembly  46  and carrier bushing  56 . As shown in  FIG. 3 , top and bottom gearbox isolation rings,  60  and  62  respectively, are positioned between gearbox  58  and mounts  28  (which are formed on base  26 ) for the purpose of minimizing any vibrations created by pencil sharpener  10  when in use. Receptacle interlock switch  64  in is included in the exemplary embodiment. This switch defeats motor  76  when receptacle  34  is removed from base  26 . Motor insulation plate  72  is positioned within gearbox cover  74 , which attaches to gearbox  58  and encloses the first gear assembly. 
         [0021]    Advantageously, pencil sharpener  10  reduces the noise generated by the typical electric pencil sharpener by as much as 40%. The noise reducing aspects of this invention are provided by the inclusion of specific components within the device. In an exemplary embodiment, motor  76  is a high-voltage DC motor of about 120V, although other high voltage motors may be used with the present invention. Helical cutters  48  are left-handed cutters that rotate counterclockwise (from the front of the sharpener). This configuration tends to draw a pencil into the sharpener rather than pushing it out with each cut. Additionally, using right-handed helical cutters and reversing the direction of rotation also results in a pencil being drawn into the cutter and this configuration is used in alternate embodiments of this invention. Dual helical cutters  48  are mounted opposite one another on metal carrier  52  (versus the use of one cutter and a dead counterweight) for more precisely balancing carrier  52  and the cutting forces generated by helical cutters  48 . Machining the shaft portion of carrier  52  and using precision bushing  56  for isolating vibration provides more discrete control of the rotation of carrier  52 . The use of helical gearing between motor  76  and carrier  52  creates less noise than straight-cut spur gears and the use of a metal gearbox ( 58 ) with a cover ( 74 ) reduces the transmission of gear noise from within the device. Positioning elastomeric pads or o-rings  60  and  62  between the bottom of gearbox  58  and base  26 , further isolates gearbox and motor vibrations from the exterior housing of pencil sharpener  10 . Attaching elastomeric, suction cup-shaped feet to the bottom of base  26  also isolates vibrations generated within the enclosure from a surface upon which pencil sharpener  10  has been placed. 
         [0022]    With regard to other specifications, in an exemplary embodiment of this invention motor  76  is a 120 volt DC motor operating at 2500-6500 RPM, no-load speed. AC/DC conversion is accomplished by a full-wave rectifier, although a half-wave rectifier may be used to further reduce motor speed and power. With regard to the gearbox and drive train, helical gear  54  has an 8° helix angle, pinion gear  70  is an 8T pinion gear, carrier gear  66  is a 45T gear, and gear  68  is a 32T/8T double gear. The final drive ratio at carrier  52  is 1:22.5 and the carrier drive speed is about 110-290 RPM (no load). The gears are typically die-cast aluminum, although other materials may be used. Helical cutters  48  are 12-flute cutters with a case hardened to HRC  60 - 65  (at least 0.020″ deep). There is a slight undercut in the tooth profile (i.e., a slight rake angle, approximately 5° or higher) and the cutter diameters have a concentricity of 0.0015″ or better. Carrier  52  is typically die-cast zinc. Feet  32  and isolation pads  60  and  62  are thermoplastic polyurethane (TPU) or a similar elastomer. Enclosure  20  is Chi Mei ABS, Type 757 and in some embodiments a damping coating, such as latex QuietCoat, is applied to the inside of the enclosure to further dampen vibrations. Other embodiments of this invention include an auto-stop feature, such as that disclosed in U.S. patent application Ser. No. 12/826,041, which is incorporated by reference herein in its entirety, for all purposes. 
         [0023]    While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to any of the specific details, representative devices and methods, and/or illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s general inventive concept.