APPARATUS FOR SIGNATURE VERIFICATION

A method for real-time signature verification uses a transducer pad in which the pressure of a stylus causes contact to be made between two resistive films. Such a transducer is energized by current pulses to sample pairs of X and Y coordinates every 5 milliseconds. The analogue voltage outputs are converted to digital form and processed under the control of a microprocessor to determine numerical parameters each representing a significant feature of the signature pattern. A set of specimen signatures is collected and from these the mean values and standard deviations of several relevant parameters are calculated and committed to memory. The parameters for a working signature are compared with the respective stored mean values for the individual concerned. Each deviation from a stored mean value is compared with the corresponding stored standard deviation in a non-linear scoring circuit. The aggregate score derived from the comparison of several parameters is compared with a preset threshold level to decide whether or not a working signature is genuine.