Abstract:
A pencil-centering assembly for use in pencil sharpeners or the like that includes a frame; a linking member rotatably mounted within the frame; a plurality of pencil contact levers, wherein each contact lever includes a top portion and a bottom portion, wherein the top portion of each pencil contact lever is adapted to engage the linking member, wherein the bottom portion of each pencil contact lever, in combination with the other pencil contact levers, defines a pencil insertion aperture having a center axis, and wherein the bottom portion of each pencil contact lever extends in to the pencil insertion aperture to about the same distance; and at least one biasing member in contact with the linking member, wherein the biasing member exerts force on each pencil contact lever by way of the linking member sufficient to bias each pencil contact lever toward the center axis of the pencil insertion aperture.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The described invention relates in general to sharpening devices, and more specifically to a sharpener for use with pencils or other items, wherein the sharpener includes an integrated pencil-centering mechanism and optional pencil diameter selection dial. This invention also relates to an electric pencil sharpener having a tool-less cutter-carrier replacement feature that uses only one electrical switch for both pencil insertion activation and electrical interlock when the cutter-carrier is accessed for replacement. Certain aspects of this invention may be used with mechanical (i.e., crank sharpeners) and/or electric sharpeners that are consumer products or that are intended for commercial or industrial applications. 
         [0002]    Pencils are commonly used writing or marking implements that must be regularly sharpened during use. One of the most frequent user complaints with regard to pencil sharpeners is that the pencil core is not sharpened evenly, with the graphite core being centered in the body of the sharpened pencil. A contributing factor to this problem is that the user of the pencil does not insert the pencil into the sharpener directly on axis with the internal cone of the cutter-carrier assembly of the sharpener. This may occur if the pencil is not supported radially where it enters the cutter-carrier, either due to too large an aperture (in mechanical or electric pencil sharpeners) or in some cases, in electric pencil sharpeners, due to a pencil switch actuation slide or lever that biases the pencil to one side. Commercially available electric pencil sharpeners typically include only one slide or lever which biases the pencil radially to one side and tends to push it off the axis of the cutter-carrier. Some known designs attempt to negate this effect by using two opposing slides or levers. One slide or lever actuates an electric switch while the other counteracts the switch force from the other side of the pencil. This two-slide design is an improvement, but the pencil is sometimes provided with minimal support perpendicular to the slides or levers and the self-centering tendency is often weak because the slides are mechanically independent (i.e., unlinked) and the centering effect is due to the difference between the two spring forces driving the slides or levers. Thus, there is an ongoing need for a sharpener with an effective centering mechanism. 
         [0003]    Commercially available pencil sharpeners also typically include a simple rotating disc with a plurality of apertures having different diameters for supporting pencils of various sizes and/or shapes. This disc is positioned on an axis offset by some distance from the pencil entry aperture of the cutter-carrier with the apertures typically positioned on a circle with a radius equal to that distance so that the holes are concentric with the sharpener&#39;s cutter-carrier. With offset rotating aperture pencil-size-selection discs that are common in electric pencil sharpeners, when presented on the outside of the sharpener, with all possible pencil apertures visible, there is some ambiguity about which aperture leads to the cutter-carrier (sharpening) mechanism. In some cases, it is the aperture directly above (behind) the center axis of the dial, and in other cases, it is the aperture directly below (in front of) the dial axis. In some electric pencil sharpeners, the rotating selector dial is recessed internally within the enclosure of the sharpener, leaving only the outer circumference portion accessible for adjustment, then presenting only one pencil-entry aperture on the external enclosure. However, this makes it more difficult for the user to select the correct aperture because not all of the choices are visible at once and the direction of increasing or decreasing size is unclear. Thus, there is an ongoing need for a sharpener with an easy to understand and effective size indicator and size limiting dial. 
         [0004]    Because the helical cutters used in electric pencil sharpeners are the primary wearing component, it is useful to provide a convenient (quick and tool-free) means of replacement when these parts eventually wear out. This can be accomplished by providing a removable cap or cover that allows user access to a removable cutter-carrier assembly. However, care must be taken so that the cutter(s) and the motor driving the cutter(s) cannot be activated while the cap or cover, which normally provides mechanical shielding from the rotating cutter(s), is removed. Such protection is commonly provided in electrical equipment by an interlock switch. It is the best practice in the industry to implement these types of interlock switches with mechanical guarding so that the switches cannot be intentionally or inadvertently reactivated (bypassed) by a finger. In existing electric pencil sharpeners that have removable covers for accessing the cutter-carrier assembly for replacement, there are usually two mechanical linkages and two electrical switches that provide for motor activation on pencil insertion and safety interlock when the cover portion is removed. Further, in electric pencil sharpeners, the motor-actuation pencil switch is commonly located on the main structure of the sharpener, adjacent to the cutter-carrier assembly. The temporary removal of the cap or cover often provides the most direct access to the cutter-carrier assembly. The cap or cover, containing the pencil-contacting portions of the switch, is then removed while the electrical and drive motor components remain with the base portion of the sharpener. The cover may contain an electrical switch and remain tethered by wires to the base sharpener, but this creates design and electrical insulation complications. Thus, there is an ongoing need for a pencil-switch-to-sharpener-base linkage that can be readily disconnected and reconnected and that provides enhanced safety. 
       SUMMARY OF THE INVENTION 
       [0005]    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. 
         [0006]    In accordance with one aspect of the present invention, a first pencil-centering assembly for use with pencil-sharpeners is provided. This pencil-centering assembly includes a frame; a linking member rotatably mounted within the frame; a plurality of pencil contact levers, wherein each contact lever in the plurality of pencil contact levers includes a top portion and a bottom portion, wherein the top portion of each pencil contact lever is adapted to engage the linking member, wherein the bottom portion of each pencil contact lever, in combination with the other pencil contact levers, defines a pencil insertion aperture having a center axis, and wherein the bottom portion of each pencil contact lever extends in to the pencil insertion aperture to about the same predetermined distance; and at least one biasing member in contact with the linking member, wherein the at least one biasing member exerts force on each pencil contact lever by way of the linking member sufficient to bias each pencil contact lever toward the center axis of the pencil insertion aperture. 
         [0007]    In accordance with another aspect of the present invention, a second pencil-centering assembly for use with pencil-sharpeners is provided. This pencil-centering assembly includes frame, wherein the frame is adapted to be detachably mounted within the housing of a pencil sharpener; a linking member rotatably mounted within the frame; a plurality of pencil contact levers, wherein each contact lever in the plurality of pencil contact levers includes a top portion and a bottom portion, wherein the top portion of each pencil contact lever is adapted to engage the linking member, wherein the bottom portion of each pencil contact lever, in combination with the other pencil contact levers, defines a pencil insertion aperture having a center axis, and wherein the bottom portion of each pencil contact lever extends in to the pencil insertion aperture to about the same predetermined distance; and a plurality of biasing members connected to the linking member, wherein the each biasing member exerts force on each pencil contact lever by way of the linking member sufficient to bias each pencil contact lever toward the center axis of the pencil insertion aperture. 
         [0008]    In yet another aspect of this invention, a third pencil-centering assembly for use with pencil-sharpeners is provided. This pencil-centering assembly includes a frame, wherein the frame is adapted to be detachably mounted within the housing of a pencil sharpener; a linking member rotatably mounted within the frame; a plurality of pencil contact levers, wherein each contact lever in the plurality of pencil contact levers includes a top portion and a bottom portion, wherein the top portion of each pencil contact lever is adapted to engage the linking member, wherein the bottom portion of each pencil contact lever, in combination with the other pencil contact levers, defines a pencil insertion aperture having a center axis, wherein the bottom portion of each pencil contact lever extends in to the pencil insertion aperture to about the same predetermined distance, and wherein each pencil contact lever includes a cam lobe formed in the bottom portion thereof; at least one biasing member connected to the linking member, wherein the at least one biasing member exerts force on each pencil contact lever by way of the linking member sufficient to bias each pencil contact lever toward the center axis of the pencil insertion aperture; a pencil size selector dial rotatably attached to the frame and concentrically located with the pencil insertion aperture, wherein the pencil size selector dial further includes a plurality of pencil size indicators located on the exterior of the pencil size selector dial, wherein each indicator corresponds to a predetermined pencil size limit; a cam surface located on the interior of the pencil size selector dial, wherein upon insertion of a pencil into the pencil insertion aperture, the cam lobes on each pencil contact lever move outward toward the cam surface, wherein the travel distance of each pencil contact lever is restricted from the point of contact of each cam lobe to the cam surface; and wherein the relative location of each cam lobe is varied slightly on each pencil contact lever such that each cam lobe contacts a unique position on the cam surface at each discrete orientation of the pencil size selector dial. 
         [0009]    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 
         [0010]    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: 
           [0011]      FIG. 1  is a front view of a pencil-centering mechanism, in accordance with an exemplary embodiment of the present invention; 
           [0012]      FIG. 2  is a front view of the pencil-centering mechanism of  FIG. 1 , showing a pencil centered within the pencil-centering mechanism; 
           [0013]      FIG. 3  is a front view of a pencil-size selector dial, in accordance with an exemplary embodiment of the present invention; 
           [0014]      FIG. 4  is a front view of an alternate pencil-size selector dial, in accordance with another exemplary embodiment of the present invention; 
           [0015]      FIG. 5  is a front view of the lever and cam assembly that accommodates variable diameters of pencils inserted into the sharpener, in accordance with an exemplary embodiment of the present invention; 
           [0016]      FIG. 6  is a first perspective view of the cap assembly removed from the housing of a pencil sharpener, in accordance with an exemplary embodiment of the present invention; 
           [0017]      FIG. 7  is a second perspective view of the cap assembly removed from the housing of a pencil sharpener, in accordance with an exemplary embodiment of the present invention; and 
           [0018]      FIG. 8  is a side view of an intermediate pushrod that is used in certain embodiments of this invention to actuate an electrical switch. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    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. 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. 
         [0020]    The present invention provides a pencil sharpening system that includes several advantageous features, including (i) a pencil-centering mechanism that aligns a pencil to be sharpened with the axis of the cutter-carrier device that sharpens the pencil; (ii) a rotatable pencil diameter/shape selecting dial that is mechanically linked to the pencil-centering mechanism for limiting the size of the aperture into which the pencil may be inserted; and (iii) a single separable mechanical linkage between a pencil and an electric motor activation switch that also acts as an interlock for the electric motor of the sharpener. 
         [0021]    In the exemplary embodiment of this invention shown in the Figures, at least three rotating levers or slides are arranged around the pencil (or other item to be sharpened) for maintaining the position of the pencil on-center with the cutter-carrier axis of the sharpener. These levers are also mechanically linked by an additional rotary member and the entire mechanism is biased with a spring or springs so that the pencil-contacting points of the levers are directed inwards toward the cutter-carrier axis. When a pencil is inserted without any external bias applied thereto, it will come to rest with its axis in alignment with the axis of the cutter-carrier, with each lever or slide applying a near-equal, inward, radial force to the pencil. If an external radial bias is applied (e.g., by the user&#39;s hand), the lever located nearest in that radial direction will resist any motion of the pencil with an increasing force while the levers in the other directions will gradually push on the pencil with reduced force and potentially to zero force. This may continue until the opposing lever is providing all of the center-returning force and the opposite levers are providing none. The centering mechanism, therefore, provides a strong return-to-center tendency to the pencil. 
         [0022]    With specific reference to  FIGS. 1-2 and 5 , an exemplary pencil centering mechanism  110  includes frame  112 , linking member  114 , and variable cam surface  116 . Linking member  114  includes first notch  120 , first contact surface  122  having post  124  formed thereon, first biasing member  126 , and second contact surface  128 , wherein first biasing member  126  is disposed between first and second contact surfaces  122  and  128  respectively. Linking member  114  also includes second notch  130 , third contact surface  132  having post  134  formed thereon, second biasing member  136 , and fourth contact surface  138 , wherein second biasing member  136  is disposed between third and fourth contact surfaces  132  and  138  respectively. Linking member  114  also includes third notch  140 , fifth contact surface  142  having post  144  formed thereon, third biasing member  146 , and sixth contact surface  148 , wherein third biasing member  146  is disposed between fifth and sixth contact surfaces  142  and  148  respectively. 
         [0023]    Again with reference to  FIGS. 1-2 , centering mechanism  110  further includes three levers, equally-spaced at angles of about 120° for centering pencil  182  within pencil insertion aperture  180 . These levers are linked to one another by linking member  114  such that the levers extend into pencil insertion aperture  180  to approximately the same distance. The levers are biased toward the center axis of pencil insertion aperture  180  by first, second, and third biasing members  126 ,  136 , and  146 , which in the embodiment shown in the Figures, are springs. First lever  150  includes pencil-contacting bottom portion  152  that further includes first cam lobe  154 , and top portion  156  that further includes protrusion  158 . Protrusion  158  engages first notch  120  in linking member  114 . Second lever  160  includes pencil-contacting bottom portion  162  that further includes second cam lobe  164 , and top portion  166  that further includes protrusion  168 . Protrusion  168  engages second notch  130  in linking member  114 . Third lever  170  includes pencil-contacting bottom portion  172  that further includes third cam lobe  174 , and top portion  176  that further includes protrusion  178 . Protrusion  178  engages third notch  140  in linking member  114 . Bottom portions  152 ,  162 , and  172  extend equally into pencil insertion aperture  182  and are held in place by force exerted on each of the three levers  150 ,  160 , and  170  by biasing members  126 ,  136 , and  146  respectively. In the embodiment shown in  FIGS. 1-2 , the biasing members act on the three levers through linking member  114 ; however, in one or more alternate embodiments, the biasing members may act on the levers directly. 
         [0024]    Certain embodiments of this invention also include a rotating selector dial that provides a visual representation of the maximum diameter and/or specific geometry of the pencil or other item that can be placed into pencil insertion aperture  180 . This rotatable selector dial is mechanically coupled to a cam device that cooperates with cam lobes  154 ,  164 , and  174  to limit the travel distance of levers  150 ,  160 , and  170 . With specific reference to  FIGS. 3-5 , a first exemplary rotatable selector dial  200  ( FIG. 3 ) includes pencil size/geometry selection indicators  202 , wherein indicators  202  represent various available pencil diameters and shapes and are positioned concentrically around the pencil insertion aperture. A second exemplary selector dial  300  ( FIG. 4 ) includes rotatable selector dial  300 , which further includes visual indicator  304 , which may be a mark, notch, ridge, or other structure, and size indicators  302 , which are fixed around the perimeter of the face of the sharpener. In this embodiment, indicators  302  represent various available pencil sizes and shapes, while visual indicator  304  provides a clear visual representation of the particular pencil size/shape that has been selected. 
         [0025]    With reference to  FIG. 5 , for both of the selector dials described above, variable cam surface  116  is attached to the inside of the rotating selector dial. Upon insertion of pencil  182  into pencil insertion aperture  180 , the cam lobes  154 ,  164 , and  174  on each pencil contact lever  150 ,  160 , and  170  respectively move outward toward cam surface  116 . The travel distance of each pencil contact lever is restricted from the point of contact of each cam lobe with variable cam surface  116 . The complex shape of cam surface  116  is designed to match a given selected pencil size limit. In the embodiment shown in  FIG. 5 , the relative location of cam lobes  154 ,  164 , and  174  on pencil contact levers  150 ,  160 , and  170  is varied slightly on each lever so that each cam lobe contacts a unique position on variable cam surface  116  at each of the discrete positions of the pencil size/shape selector dial  200  or  300 . 
         [0026]    Certain embodiments of this invention also provide a single mechanical linkage between a pencil and an electric motor activation switch that separates when cap  400  (see  FIGS. 6-7 ) is removed, and that also interlocks the electric motor (and rotating cutters) and blocks inadvertent reactivation, when cap  400  is removed. By mechanically shielding an electro-mechanical pencil-insertion switch so that a human finger cannot be inserted and disconnecting the mechanical linkage between a pencil and an electrical switch when cap  400  is removed, the pencil/switch system also serves as the safety interlock. Since only one electrical switch is needed and the associated wiring, splicing, and assembly labor are eliminated, the cost of the pencil sharpener can be reduced. Similarly, the mechanical component (structure) design can be simplified and the overall component count can be reduced. 
         [0027]    With specific reference to  FIGS. 1-2 and 6-7 , in an exemplary embodiment of this invention, the motor of an electric pencil sharpener is activated by switch subassembly  190 , which includes electrical switch  198  and switch activation pin  196 . In this embodiment, protrusion  192 , which is formed on or attached to linking member  114  in a coplanar manner, includes an inclined surface  194 . When detachable cap assembly  400 , which includes centering mechanism  110  and rotatable selector dial  200  mounted therein, is properly inserted into opening  502  in sharpener housing  500 , inclined surface  194  enters switch guard slot  195  and abuts activation pin  196 . When pencil  182  is inserted into pencil insertion aperture  180  and rotates or displaces levers  150 ,  160 , and  170 , which then moves linking member  114 , inclined surface  194  slides along switch activation pin  196 , thereby actuating electrical switch  198  and starting the electrical motor of the sharpener. When pencil  182  is removed from pencil insertion aperture  180 , biasing members  126 ,  136 , and  146  will return the entire mechanism to the starting position. When cap assembly  400  is removed from sharpener housing  500  for purposes of accessing cutter/carrier assembly  504 , inclined surface  194  on protrusion  192  is no longer in proximity to switch activation pin  196  and thus cannot actuate electrical switch  198 . Recessing switch activation pin  196  within switch guard slot  195  prevents any accidental activation of electrical switch  198  by, for example, the finger of a user of the device. 
         [0028]    With reference to  FIG. 8 , in an alternate embodiment of this invention, switch subassembly  190  is located more remotely from centering mechanism  110  and intermediate pushrod  600  is used to activate or deactivate electrical switch  198  when cap assembly  400  is attached to or removed from housing  500 . Intermediate pushrod  600  includes angled surface  602 , which is formed on front portion  604 , as well as middle portion  606  and rear portion  608 . In this embodiment, protrusion  192  on linking member  114  is oriented (at an angle of about 90° relative to linking member  114 ) such that inclined surface  194  faces rearward. Protrusion  192  cooperates with angled surface  602  on intermediate pushrod  600  to move the pushrod forward such that rear portion  608  engages switch activation pin  196  when pencil  182  is inserted into pencil insertion aperture  180 . Removing cap assembly  400  from housing  500  causes rear portion  608  of intermediate pushrod  600  to disengage from switch activation pin  196  such that electrical switch  198  cannot be activated. 
         [0029]    While the present invention has been illustrated by the description of exemplary embodiments thereof, and while the embodiments have been described in certain detail, there is no intention 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 general inventive concept.