Patent Publication Number: US-7581573-B2

Title: Electric pencil sharpener

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention generally relates to an office product, more particularly the present invention relates to a pencil sharpener capable of automatic sharpening and feeding different pencils with different sizes at one time. 
   2. Background of the Invention 
   As known to those who skilled in the art, numerous innovations for pencil sharpeners have been provided in the prior art that will be described hereafter. Even though these innovations may be suitable for the specific individual purposes to which they address. There are still many technical issues waiting to be solved. 
   A typical pencil sharpener is presented, U.S. Pat. No. 5,394,613 honored to Ku teaches a spring-driven pencil sharpener including a top cap having a top opening to receive a pencil and two corresponding slots to receive a fastening device including a couple of hollow frames, a housing which is constructed with a pair of coupling castings, each of which being accompanied by a lateral cover, for disposing a pencil blade set and a spring-driven powering device and the outline of the housing is preferably designed to cooperate with that of the cap to form an egg-like shape for being held comfortably as well as looking nice. 
   Another conventional pencil sharpener, U.S. Pat. No. 6,065,514 to New discloses a portable, handheld, sharpening device for sharpening a cosmetic pencil having an outer casing of hard material and an inner casing of soft wax-like cosmetic material. The device includes a plastic housing, a steel blade for removing the outer casing of material from the cosmetic pencil while providing a tip having a radius of no larger than about ⅛″ to the inner core of cosmetic material and a motor coupled to the blade to rotate the blade that is connected to at least one battery. The device is small and lightweight so that it can conveniently be stored in a pocket or a purse. 
   In the related art, the blade can be driven by a motor to sharpen the pencil, however, the wood-cased pencil has to be hold and gradually fed into the sharpener. It is so inconvenient to manipulate the sharpening process. Moreover, in conventional pencil sharpeners, dealing with different pencils is feasible, and automatically sharpening pencils is feasible, but no traditional pencil sharpener possesses merits of both pencil automatic feeding and automatic sharpening process simultaneously. 
   Accordingly, an electric pencil sharpener having specific configuration that overcomes the above-mentioned problems is desired. 
   SUMMARY OF THE INVENTION 
   One object of the present invention is to provide an electric pencil sharpener capable of automatic sharpening and feeding different pencils with different sizes at one time, overcoming the shortcomings of the above mentioned prior art. 
   Further objects and features of the invention will be readily apparent to those skilled in the art from the following specification that includes the appended claims and drawings. 
   Briefly stated, to achieve the above objects in accordance with the purpose of the invention, in a preferred embodiment, an electric pencil sharpener comprises a base, a powering device, a feeding subassembly, a cutter subassembly and an adjusting subassembly. Two brackets are mounted on the base, standing on the base face to face. The two brackets defines a feeding space therebetween, each of the brackets defines two guideways therein. The powering device is attached to the base. The feeding subassembly comprises a feeding gear module and a pair of feeding rollers. The feeding rollers are respectively supported in corresponding guideways, spanning across the feeding space defined between the brackets. The feeding gear module driven by the powering device makes one of feeding rollers to rotate with the feeding gear module. The adjusting subassembly encompasses the pair of feeding rollers on the bracket. The adjusting subassembly comprises a cage, a cap covering one end portion of the cage, and two masses respectively jointing two end portions of shafts of the feeding rollers extending out from the feeding space through the guideways. A pillar is vertically mounted on each of the two masses. A path for riding the pillars is formed along the circumferential inner surface of the cage. An elastic member encompassing the feeding space is mounted between the cap and the two pillars to exert a reciprocating force on the pillars so that the pillars can be ridden in close proximity along the path in the cage. The adjusting subassembly pushes the pair of feeding rollers to move along the guideways simultaneously. With restriction of the guideways, the distance between the two feeding rollers alters so that pencils with different size can be processed. 
   Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of a preferred embodiment of the present invention with the attached drawings, in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of inner structures of a electric pencil sharpener in accordance with a preferred embodiment of the present invention, comprising two brackets, a powering device, a feeding subassembly, a cutter subassembly and an adjusting subassembly; 
       FIG. 2  is an assembled view of the adjusting subassembly of the electric pencil sharpener shown in  FIG. 1 ; 
       FIG. 3  is an enlarged view of the support bracket in  FIG. 1 , viewed from another aspect; 
       FIG. 4  is the section view of the cage shown in  FIG. 1 , viewed from another aspect; and 
       FIG. 5  is a partial view of the adjusting subassembly in  FIG. 2 , but viewed from another aspect. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Throughout the drawings, the same reference numerals and characters, unless otherwise stated, are used to denote like features, elements, components or portions of the illustrated embodiments. Moreover, while the subject invention will now be described in detail with reference to the drawings, it is done so in connection with the illustrative embodiment. It is intended that changes and modifications can be made to the described embodiment without departing from the true scope and spirit of the subject invention as defined by the appended claims. 
   Referring to  FIG. 1  to  FIG. 3 , an electric pencil sharpener in accordance with a preferred embodiment of the present invention includes a base (not shown in the drawings), a powering device, a cutter subassembly, a feeding subassembly, and an adjusting subassembly. 
   The base is constructed with traditional configuration. For this purpose, the base can be integrated with an external shell. Advantageously, the external shell forms a plurality of support surfaces to ensure proper positioning and alignment of the various subassemblies, in the x-, y- and z-directions. For easy assembly purpose, the external shell may include a first external shell and a second external shell attached to each other. The first external shell is mated with second external shell to define a substantially closed compartment, serving as the sole means of mounting the components mentioned supra in the compartment. 
   Two brackets  31 ,  32  are mounted on the base, standing thereon and defining a feeding space between two brackets  31 ,  32 . Each of the brackets  31 ,  32  defines a pair of guideways  35  therein. The guideways  35  in each of the brackets  31 ,  32  are symmetrically defined so as to generate a synchronous route for the feeding subassembly. 
   The powering device is attached to the base, which comprises a motor  12  outputting rotation by a pinion  10  and a transmission device. The transmission device comprises a gear train, a drive shaft  8 , a blade holder  5 , and a crown gear  18 . The gear train includes first gear  11  meshing with the pinion  10  of the motor  12 , a second gear  16  and a third gear  9 . The drive shaft  8 , the blade holder  5 , and the crown gear  18  are successively connected with one another, and capable of pivoting along with the third gear  9 . The crown gear  18  defines a throughbore (not shown), and the throughbore is configured as an inlet for receiving a pencil to be processed. 
   The cutter subassembly comprises a helical blade  17  and the blade holder  5 . The helical blade  17  revolves along with the blade holder  5 . An internal gear  7  rested upon the base is in close proximity to the blade holder  5 . The blade holder  5  forms a shaft (not shown). The helical blade  17  is set on the shaft forementioned, and a planet gear (not shown) is engaged with the helical blade  17  at one end thereof. The planet gear meshes the internal gear  7  on the base. The helical blade  17  revolves along with the blade holder  5 , whilst the planet gear at the end of the helical blade  17  travels around the internal gear  7  so as to cause self-rotation of the helical blade  17 , and the self-rotating helical blade  17  sharpens the pencil. Pencil sharpening continues until the pencil touches a sensor block  6  to trigger the motor  12  pivoting on a reversal direction and the pencil will be retreated from the cutter subassembly after being sharpened. 
   The feeding subassembly comprises a feeding gear module, a first feeding shaft  29 , a second feeding shaft  30 , a feeding roller  24  combining with the first feeding shaft  29 , and a feeding roller  23  combining with the second feeding shaft  30 . The feeding gear module comprises a duplicate gear  19  meshing with the crown gear  18  of the transmission device, and a feeding gear  21  meshing with the duplicate gear  19 . The feeding rollers  23 , 24  together with the first and second feeding shafts  29 ,  30  are respectively supported on the brackets  31 ,  32  through corresponding guideways  35 , spanning over the feeding space between the brackets  31 ,  32 . The feeding gear  21  of the feeding gear module makes the feeding roller  30  to rotate along with the feeding gear  21 , so that when the pencil is sandwiched between the two feeding rollers  23 ,  24 , torque successive from the motor  12 , gear train, drive shaft  8 , blade holder  5 , crown gear  18 , duplicate gear  19 , feeding gear  21  to the feeding shaft  30  drives the sandwiched pencil to go toward the cutter subassembly. 
   For different pencil sharpening purpose, distance between the two feeding shafts  29 ,  30  is adjustable, meanwhile value of the distance between the two feeding shafts  29 ,  30  can also determine the friction force between pencil and the feeding rollers  23 , 24 . 
   Advantageously, the center line of the cutter subassembly is aligned with the center between the two feeding rollers  23 ,  24 , so that the pencil to be processed after getting through the feeding rollers  23 ,  24 , can directly goes into the cutter subassembly in sharpening position without additional adjustment. 
   Referring to  FIG. 3  to  FIG. 5 , the guideways  35  in each of the brackets  31 ,  32  are symmetrically defined so as to generate a synchronous route for the feeding rollers  23 ,  24  of the feeding subassembly. On condition that both the feeding rollers  23 ,  24  goes upwards, the feeding rollers  23 ,  24  approach each other and the distance therebetween minishes, pencils with small size can be sharpened. While both the feeding rollers  23 ,  24  goes downwards, the feeding rollers  23 ,  24  depart from each other and the distance therebetween increases, pencils with large size can be sharpened (in  FIG. 3 ). 
   The guideways  35  in each of the brackets  31 ,  32  are defined in a annular shape in that when both the feeding rollers  23 ,  24  goes upwards or downwards, the feeding gear  21  will mesh the feeding shaft  30  all along, to form a clear feeding path. 
   The adjusting subassembly encompasses the feeding rollers  23 ,  24  on the bracket  31 ,  32 . Said adjusting subassembly comprises a cage  22 , a cap  1  covering one end portion of the cage  22 , and two masses  27 ,  28  respectively jointing two end portions of the feeding shaft  29 ,  30  extending out from the feeding space through the guideways  35 . A pillar  3 ,  20  is mounted on each of the two masses  27 ,  28 . The pillars  3 ,  20  are settled on a path  39  formed on the inner surface of the cage  22 . The path  39  along the circumferential inner surface of the cage  22  is configured to ride the pillars  3 ,  20 . The path  39  inside the cage  22  is symmetrical along the circumferential direction of the cage  22 . An elastic member  2  encompassing the feeding space is mounted between the cap  1  and the two pillars  3 ,  20  to exert a reciprocating force on the pillars  3 ,  20  in order to ride the pillars  3 ,  20  in close proximity along the path in the cage. The elastic member  2  in the preferred embodiment of the present invention is a spring. 
   The adjusting subassembly pushes the feeding rollers  23 ,  24  to move along the guideways  35 . With restriction of the guideways  35 , the distance between the two feeding rollers  23 ,  24  alters so that pencils with different size can be processed. 
   The electric pencil sharpener further comprises a pencil quitting subassembly. The quitting subassembly comprises the sensor block  6 , a rod  15 , and a switch  14 . After the pencil has been sharpened, it triggers the sensor block  6 , then the sensor block  6  pushes the rod  15  getting through the drive shaft  8  to trigger the switch  14 , finally the motor  12  rotates in a reversal direction. 
   The shafts distance adjusting process of the exemplary electric pencil sharpener of the present invention is listed as follows: rotate the cap  1 , and the cage  22  engaged with the cap  1  rotating therealong. As the cage  22  rotates, the pillars  3 ,  20  parked on the path  39  begin to run along the path  39 . When the pillars  3 ,  20  climb up to a peak of the path  39 , the masses  27 ,  28  engaged with the feeding shafts  29 ,  30  will push the feeding shafts  29 ,  30  to move up along the guideways  35 , at the same time, the elastic member  2  is compressed. When the pillars  3 ,  20  fall down to a trough of the path  39 , the masses  27 ,  28  and the feeding shafts  29 ,  30  will get down along the guideways  35 , meanwhile, the elastic member  2  is decompressed. On condition that both the feeding shafts  29 ,  30  goes upwards, the feeding rollers  23 ,  24  approach each other and the distance therebetween minishes, pencils with small size can be sharpened. While both the feeding shafts  29 ,  30  goes downwards, the feeding rollers  23 ,  24  depart from each other and the distance therebetween increases, pencils with large size can be sharpened. 
   While the present invention has been illustrated by the description of the preferred embodiment thereof, and while the preferred embodiment have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications within the spirit and scope of the present invention will readily appear to those skilled in the art. Therefore, the present invention is not limited to the specific details and illustrative examples shown and described.