Graphics input tablet with three-dimensional data
Patent 4798919 Issued on January 17, 1989. Estimated Expiration Date: 
March 11, 2008. 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.
March 11, 2008. 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 ReferencesElectrographic touch sensor with Z-axis capability Patent #: 4687885 InventorsApplicationNo. 07/166957 filed on 03/11/1988US Classes:178/18.05ResistiveExaminersPrimary: Schreyer, Stafford D.Attorney, Agent or FirmInternational ClassG06F 3/033 (20060101)Foreign Application Priority Data1987-04-28 GBAbstractA graphics input tablet has a conductive layer and a resistive layer with contacts (16,17,23,24) arranged one along each edge of the resistive layer. The conductive layer is held at a negative potential relative to the resistive layer so current flows in each contact when localized pressure is applied to a region of the tablet (20) to bring the layers into electrical contact. The currents vary with both position and magnitude of the localized pressure. The position of the pressure is detected from the relative currents in opposed contacts and the magnitude of the pressure is detected from the total current in the contacts. The currents are measured by current sense amplifiers and processed in a computer. Analogue front-end processing of the currents is also possible. | |
