ELECTROCHEMICAL GAS SENSOR WITH REDUCED CROSS-SENSITIVITY

摘要

The system uses a number of detectors(21;A-S), each producing an output signal having a first or second state depending upon the absence or presence of a writing instrument(13) in a discrete zone on a surface. Sensors (23,24) periodically detect, when the character is written by the writing instrument on the surface, the state of the output signal, and means (25) determines from the output signals which signals are in the second state. Each of the output signals in the second state is compared (25,26) with the state of the output signal produced by the same detector at the time of the preceding detection state. An identifier corresponding to the detectors for which a state change has been detected is recorded (26,28) in a predetermined detector order. The recorded identifiers form a series of identifiers corresponding to the transcribed character. The series of recorded identifiers is compared (27,29) with a reference series in order to identify the transcribed written.