Acoustic writing combination, comprising a stylus with an associated writing tablet Patent #: 4246439
ApplicationNo. 07/127730 filed on 12/02/1987
US Classes:178/19.02, Acoustical stylus178/19.07, Multifrequency345/177, Including surface acoustic detection345/183, Light pen for controlling plural light-emitting display elements (e.g., LED, lamps)367/907COORDINATE DETERMINATION
ExaminersPrimary: Schreyer, Stafford D.
Attorney, Agent or Firm
International ClassesG06F 3/033 (20060101)
G01S 5/00 (20060101)
G01S 5/30 (20060101)
AbstractThis invention is an input device, or stylus, for entering hand drawn forms into a computer comprising a writing instrument, a pressure switch for determining whether the instrument is in contact with the writing surface, an acoustic transmitter for triangulating the position of the stylus on the surface, and a wireless transmitter for transmitting data and timing information to the computer. In operation, the stylus transmits an infra red signal which the system receives immediately, and an ultra sound pulse which two microphones receive after a delay which is a function of the speed of sound and the distance of the stylus from each microphone. From this information the system can calculate the position of the stylus. Switches for indicating functions are mounted on the stylus. Multiple stylusses can be used, each transmitting a distinctive identification code so that the system can determine which stylus is the signal source.