Patent Publication Number: US-6338198-B1

Title: Pencil sharpener

Description:
This application claims the benefit of U.S. Provisional Application Serial No. 60/147,429 filed on Aug. 5, 1999. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to pencil sharpeners and more particularly to pencil sharpeners adapted to sharpen carpenter or construction pencils having a rectilinear cross-section. 
     BACKGROUND OF THE INVENTION 
     The commonly known carpenter or construction pencil is characterized as being rectangular in cross-section with a width that is almost twice that of its thickness. Such pencils are constructed of a wood covering and a graphite core or lead. The core also has a generally rectangular or oblong cross-section. 
     The carpenter or construction pencil is used by carpenters and construction workers and also artists and others. However, such pencils have problem with respect to sharpening. Since almost all pencil sharpeners accept only pencils having a generally round cross-section, such sharpeners cannot be effectively used with construction or carpenters pencils. With pencils having around cross-section sharpening is attained by rotary sharpeners, which revolve about a stationary pencil or with stationary blades, which cut or peel a point on a rotating pencil. None of these offer a practical possibility for sharpening carpenter pencils. As a result, the typical method of sharpening carpenters&#39; pencils is to use a penknife or the like to whittle a rough point or to use sand paper to abrade a point. 
     Pencil sharpeners for carpenters&#39; pencils have been provided but such sharpeners rely on rotating cutters. Such sharpeners typically are large and cumbersome and require a stationary mounting to be effective. There is a need for a pencil sharpener for carpenter pencils, which is readily available to a user operating in the field. Preferably such a sharpener not only should be readily available but also if possible, easily carried in the users pocket or on a key chain. 
     It is an object of the invention to provide a pencil sharpener which is small and compact and which is easily carried by the user. 
     Still another object of the invention is to provide a pencil sharpener, which is cheap and economical and easy to operate. 
     Another object of the invention is to provide a carpenters pencil sharpener wherein the opposite wide sides and the opposite narrow sides are sharpened progressively in a manually operated sharpener. 
     It is another object of the invention to provide a pencil sharpener for carpenters&#39; pencils, which is small and compact and can be easily transported in the pocket of a worker in readiness for immediate use. 
     SUMMARY OF THE INVENTION 
     The objects of the invention are obtained by a pencil sharpener in which a base member has a cover member supported on the base member for movement between a first position in which flat cutting blades supported by the cover member are out of engagement with the pencil and a second position in which the blades are moved into engagement to cut opposed surfaces of the pencil which is held in a stationary position relative to the base member. The blades are arranged to converge relative to the axis of the pencil and are slightly curved to form outwardly concave cutting edges. Resilient means maintain the cover member in its first position and yieldingly resist movement to the second or cutting position. The base member is provided with apertures to receive the carpenter&#39;s pencil so that one of the openings guides the pencil to a cutting position in which the wide part of the pencil is in contact with a support surface on the base member and a second position in which the narrow side of the pencil is in abutting relation with the support surface. The cover member is movable repeatedly between first and second positions to shave the end of the pencil with the cutting blades so that sharpening the pencil is attained in two stages, one for the opposed wide surfaces of the pencil and the other for the narrow opposed surfaces of the pencil. Provision is made for tilting the pencil in each of its sharpening positions to support the core or lead for accurate finishing of the paint of the pencil. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a preferred embodiment of the invention; 
     FIG. 2 is a cross-sectional view of a carpenters pencil of the type for which the pencil sharpener of the present invention is used; and 
     FIG. 3 is an enlarged view of a portion of a carpenter&#39;s pencil in one of its positions during sharpening. 
     FIG. 4 is a longitudinal cross-sectional view of the pencil sharpener shown in FIG. 1; 
     FIG. 5 is a cross-sectional view taken on line  5 — 5  in FIG. 4; 
     FIG. 6 is a cross-sectional view taken on line  6 — 6  in FIG. 4; 
     FIG. 7 is a top cross-sectional view taken on line  7 — 7  in FIG.  4 ; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings a pencil sharpener embodying the invention is designated generally at  10 , incorporates a base member  12  and a cover member  14 . 
     The base member  12  is made up of a pair of opposed end walls  16  and  18  joined with a bottom wall  20 . The end walls  16  and  18  and bottom wall  20  are also joined together by opposed parallel sidewalls  22  to form a generally box-like structure. 
     The end wall  16  is provided with a pencil receiving opening  24  to permit insertion of a carpenter&#39;s pencil. Such a pencil is designated at  26  and an end view of an unsharpened pencil is shown in FIG.  2 . Such pencils  26  are made of wood and have opposed wide, flat surfaces  28  and opposed narrow flat edge surfaces  30 . The core  32  is of graphite and commonly referred to as a lead. When a pencil  26  is inserted in opening  24  it rests on its lower narrow edge  30  on the top surface of bottom wall  20  of base member  12 . Similarly, the opposite end wall  18  has an opening  34  as seen in FIGS. 1 and 6 to receive a carpenters pencil  26  so that it is disposed with its lower, wide side  28  on the top surface of bottom wall  20  of base member  12 . 
     The cover  14  of the pencil sharpener  10  is generally U-shaped in cross-section and as viewed in FIGS. 5 and 6, has a top wall  35  and opposed parallel side walls  36 . The spacing of the side walls  36  is slightly greater than the distance between the outside surfaces of the side walls  22  of the base member  12  so that the side walls  36  are free to move relative to the outside of the side walls  22 . The side walls  36  are provided with slots  38  which receive guide pins  40  secured in fixed position to the side walls  22  of the base member  12 . The slots  38  and pins  40  act to maintain the base and cover members  12  and  14  connected to each other and guide movement of these members relative to each other. The base member and cover member  14  are maintained in spaced apart relationship to each other by a coil spring  42  seen in FIGS. 4 and 7, having opposite ends acting between spring seats formed on the base member  12  and the cover member  14 . 
     The cover member  14  supports first pair of cutting blades  50  adjacent the end wall  16  of the base member  12  and a second pair of cutting blades  52  which are adjacent to and associated with the end wall  18  of the base member  12 . The cutting blades  50  are disposed at an angle to each other so that the cutting edges  54  extend away from the wall  16  and converge relative to each other to cut opposed surfaces  28  a pencil is positioned in the opening  24 . Similarly, cutting blades  52  converge toward each other as they extend away from the wall  18  to cut the opposed narrow edge surfaces  30  of carpenter pencil  26  when it is positioned with its end in the opening  34  seen in FIG.  6 . The position of the pencil  26  is shown in broken line at  26  in FIGS. 4 through 7. 
     The cutting blades  50  and  52  are slightly curved to give the sharpened ends of the pencil  26  a slightly concave surface, which many users find preferable to flat surfaces. It should be understood, however, that flat blades can be used. 
     The blades  50  and  52  may be supported in any conventional manner relative to the cover member  14  but preferably by it being embedded in the plastic material from which the cover member  14  is made. The base member  12  also is made of the same plastic material. 
     In use, the end of a carpenters pencil  26  is placed in a selected one of the openings  24  or  34  and the pencil sharpener  10  is squeezed to move the base member  12  and cover member  14  relative to each other against the resistance of spring  42 . This brings the cutting blades  50  or  52  into cutting engagement with the pencil  26  to cut away a layer of wood material from the end surface of the pencil  26 . 
     As viewed in FIGS. 4 and 7 pairs of stops  60  and  62  can be molded integrally with the base member  12  to protrude inwardly from the side walls  22  into close proximity with the respective blades  50  and  52 . The stops  60  and  62  act to limit the initial position of an unsharpened pencil  26  so that the thickness of the initial cut is a minimum. Repeated pressing of the base  12  and cover  14  together shaves layers of the wood covering to permit advance of the pencil  26  inwardly to expose the pencil core  32 . Assuming that a new unsharpened pencil  26  is placed in opening  34  in wall  18  first, the opposite sides  30  of the pencil  26  will be cut at an angle to expose the core  32 . Thereafter, the pencil can be placed in opening  24  in the opposite end wall  16  and after the sharpener has been repeatedly activated, the pencil core  32  will be reached. At this point the pencil  26  can be tilted as shown in FIG. 3 so that a previously cut pencil end rests against the top surface of the bottom wall  20 . Such tilting is permitted because the vertical extent of both the openings  24  and  38  is slightly larger than an actual pencil as best seen in FIGS. 5 and 6. 
     After a pencil has been sharpened the first time, the pencil can be disposed at an angle in either opening  24  or  34  such tilting supports the core  32  against the upper surface of the bottom wall  20  which acts as an anvil and may be of assistance to support the core  32 , particularly if it is made of soft material. 
     As mentioned previously, after sharpening of the pencil  26  utilizing both the openings  24  and  34 , pencil  26  has a tapered end in which the surfaces are slightly concave. 
     The shavings, which result from sharpening of a pencil, are free to fall through openings  64  and  66  seen in FIG. 7 formed in the bottom wall  20  of base  12 . Openings  64  are disposed outwardly from the blades  50  and openings  66  are outwardly of blades  52  leaving the top surface of bottom wall  20  between the blades and between the openings  60  to support the surface of a pencil during the cutting operation. 
     A pencil sharpener for sharpening carpenter&#39;s pencils or the type having a generally oblong or rectilinear cross-section has been provided by which such pencils can be mechanically sharpened accurately in a minimum amount of time and without the need to use pen knifes or sand paper. Moreover, the point formed with the sharpener gives a slightly concave contour to opposed edges which more closely approximates the type of surface that can be obtained by time consuming manual sharpening to give a fine point to the exposed lead or core repeatedly and uniformly. The sharpener is compact and easily transported on the person of the user.