Non-slip screw
Patent 4538486 Issued on September 3, 1985. Estimated Expiration Date: 
November 21, 2003. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
November 21, 2003. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 38141 132946 1056095 2631624 2684094 2792039 3540342 3695321 Screw driver and screw head system Patent #: 4311071 InventorApplicationNo. 06/554140 filed on 11/21/1983US Classes:81/460, Inserted portion having plural, noncollinear blades (e.g., Phillips)411/407Having driver retaining meansExaminersPrimary: Smith, Gary L.Assistant: Whitcomb, Adrian H. Jr. Attorney, Agent or FirmInternational ClassesB25B 15/00 (20060101)F16B 23/00 (20060101) Foreign Application Priority Data1982-11-22 FRAbstractA non-slip screw of the type having a threaded shank and a slotted head, including a locking surface defined in the screw head by a central transverse slot which extends across the top of the head for engagement with a screwdriver blade tip. The locking surface includes a pair of radially outwardly extending inclined walls extending downwardly from each end of the transverse slot. An especial screwdriver having its exterior blade tip configured complementally with the pairs of radially outwardly extending inclined walls is engageable with the locking surface, so as to rotate the screw head in either direction. The screw head is characterized by its positive grip with the screwdriver blade tip, notwithstanding actual screwdriving or unscrewing and removal of the screw. | |
