Postal weighing apparatus and method

Abstract

A postal scale having an improved response time to determine appropriate postage amounts and including an improved postal weighing algorithm. The scale includes a transducer which produces a sequence of digital output signals representative of the instantaneous response of a scale and a microprocessor which detects the presence of mail pieces on the scale and determines estimates of the weight of the mail pieces as a function of subsequences of digital output signals, and uses these estimates to determine appropriate postage amounts. The algorithm used in the scale of the subject invention takes advantage of the fact that postal rate charts (i.e. postal rates as a function of weight) are, in general, step-like (i.e. are constant over ranges between predetermined weight breakpoints). The processor examines sequences of digital output signals and makes a first estimate of the weight of the mail pieces and determines the distance from the first estimate to the closest breakpoint. If the distance is sufficiently great the first estimate may be used safely to determine the appropriate postage amount. If the distance is close a second more accurate estimate is then made and used to determine the appropriate postage amount.