Patent References 3921166 Graphical data entry pad Electronic pressure sensitive transducer apparatus Bounceless switch apparatus Electronic pressure sensitive force transducer Touch sensitive control device Digitizer pad Digitizer pad Position detecting device Touch pad machine control InventorsAssigneeApplicationNo. 857134 filed on 05/15/1997US Classes:345/174, Including impedance detection178/18.01, Position coordinate determination for writing (e.g., writing digitizer pad, stylus, or circuitry)178/18.03, Writing digitizer pad178/18.06CapacitiveExaminersPrimary: Shankar, VijayAttorney, Agent or FirmInternational ClassesG08C 021/00G09G 005/00 AbstractA touchpad assembly and method for providing a signal to a computer indicative of the location and applied pressure of an object touching the touchpad assembly is provided. The touchpad assembly includes X and Y position and pressure sensitive semiconductor resistance sensor layers. The X and Y sensors have a pair of spaced apart X and Y conductive traces running across opposite ends such that a resistance RX connects the pair of X traces and a resistance RY connects the pair of Y traces. The X and Y sensors come into contact at a contact point when an object asserts a pressure on the touchpad. The contact point is connected to each trace by a variable pressure resistance RZ associated with the X and Y sensors and variable position resistances of the X and Y resistances. First and second pair of timing capacitors are connected to respective ones of the pairs of X and Y traces. A microprocessor controls and monitors charging time of the capacitors to determine the position and asserted pressure of the object touching the touchpad.Field of SearchTouch panelIncluding impedance detection Including optical detection With alignment or calibration capability (i.e., parallax problem) Stylus Position coordinate determination for writing (e.g., writing digitizer pad, stylus, or circuitry) Writing digitizer pad Capacitive Inductive Capacitive or inductive stylus Pressure stylus | |