Pencil sharpener

A self-governing sharpening assembly comprising:

• a housing;
• a blade-supporting shaft having a lower end and an upper end, said upper end having a reduced diameter portion;
• a rotary blade and a pinion carried co-axially on said shaft, said rotary blade having spiral cutting edges;
• a blade holder defining a conical cavity for receiving an end of a pencil therein and having a bearing lug defining a bearing opening sized to rotatably support said upper end of said shaft, said blade holder being supported by said housing to be rotatable around an axis of said conical cavity;
• an annular ring gear fixedly supported by said housing and meshing with said pinion;
• a drive shaft which drives said blade holder around said axis;
• a stop slidably mounted to said blade holder in alignment with said conical cavity, said stop being connected to said lower end of said shaft;
• and
• a spring member supported by said blade holder, said spring member engaging said stop and biasing said reduced diameter portion of said shaft away from said bearing opening of said bearing lug;
• whereby a pencil advanced into said conical cavity is sharpened by said rotary blade until said pencil is sufficiently sharpened, at which point said pencil moves said stop against the spring bias, causing said reduced diameter portion of said shaft to enter said bearing opening of said bearing lug, said reduced diameter portion being sized relatively to said bearing opening to allow for pivotal movement of said shaft and said rotary blade away from said pencil under influence of centrifugal force produced by rotation of said blade holder around the axis of said conical cavity.

A pencil sharpener comprising:

• a housing defining a pencil-receiving opening;
• a self-governing sharpening assembly mounted on said housing in alignment with said pencil-receiving opening for sharpening any pencil inserted therein, said self-governing sharpening assembly comprising a blade-supporting shaft having a lower end and an upper end, said upper end having a reduced diameter portion, a rotary blade and a pinion carried co-axially on said shaft, said rotary blade having spiral cutting edges, a blade holder defining a conical cavity for receiving an end of a pencil therein and having a bearing lug defining a bearing opening sized to rotatably support said upper end of said shaft, said blade holder being supported by said housing to be rotatable around an axis of said conical cavity, an annular ring gear fixedly supported by said housing and meshing with said pinion, a drive shaft which drives said blade holder around said axis, a stop slidably mounted to said blade holder in alignment with said conical cavity, said stop being connected to said lower end of said shaft, and a spring member supported by said blade holder, said spring member engaging said stop and biasing said reduced diameter portion of said shaft away from said bearing opening of said bearing lug, whereby a pencil advanced into said conical cavity is sharpened by said rotary blade until said pencil is sufficiently sharpened, at which point said pencil moves said stop against the spring bias, causing said reduced diameter portion of said shaft to enter said bearing opening of said bearing lug, said reduced diameter portion being sized relatively to said bearing opening to allow for pivotal movement of said shaft and said rotary blade away from said pencil under influence of centrifugal force produced by rotation of said blade holder around the axis of said conical cavity;
• and
• a receptacle removably matable with said housing for receiving pencil shavings discharged from said sharpening assembly.

A self-governing sharpening assembly comprising:

• a housing;
• a blade-supporting shaft having a lower end and an upper end;
• a rotary blade carried co-axially on said shaft, said rotary blade having a cutting edge;
• a blade holder defining a cavity for receiving an end of a pencil therein and having a bearing lug defining a bearing opening sized to rotatably support said upper end of said shaft, said blade holder being supported by said housing to be rotatable around an axis of said cavity;
• a stop slidably mounted to said blade holder in alignment with said cavity, said stop being connected to said lower end of said shaft;
• and
• a spring member supported by said blade holder, said spring member engaging said stop and biasing said shaft to an operative position in which said rotary blade is capable of sharpening a pencil advanced into said cavity;
• whereby said shaft and said bearing lug are complementarily configured to pivot said shaft from said operative position to an inoperative position responsive to longitudinal translation of said shaft, and whereby a pencil advanced into said cavity is sharpened by said rotary blade until said pencil is sufficiently sharpened, at which point said pencil moves said stop against the spring bias, causing said shaft to translate longitudinally relative to said bearing lug and to pivot said shaft and said rotary blade away from said pencil into said inoperative position under influence of centrifugal force produced by rotation of said blade holder around the axis of said cavity.