Computing weighing scale

Abstract

A computing weighing scale is disclosed wherein a single multi-digit numerical indicator is driven in real time by the scale microcomputer to display, sequentially, weight of the article, price per unit weight, and total price or value of the article. The indicators are part of a display which also includes function words identifying the nature of the information to the scale operator and customer. The scale also includes weight code generating mechanism, a keyboard for entering numerical information, and the micro-computer. The single multi-digit indicator can also display tare weight, which is entered via the keyboard when there is no weight on the platter. If tare is entered and subsequent weight on the platter is less than entered tare, the calculating function is inhibited. If platter motion is detected with weight on the platter, the display will reset to the weight indicating condition and then sequence to show again price per unit weight (if entered) and total price. When all weight is removed from the platter, entered tare is erased, tare is, however, remembered during weight changes above zero weight. Price per unit weight can be entered via the keyboard only when there is some minimum weight on the platter and is remembered for possible recalculation if weight on the platter is changed but not removed, price per unit weight is cancelled when all weight is removed from the platter. Keyboard switches are interrogated a plurality times before entered information is accepted, to assure the key entry is valid and switch contact bounce has terminated. The platter motion detector is disabled for a short time after a key actuation, to avoid system resetting as a result of platter movement which may be induced by keyboard actuation. The microcomputer scans the possible inputs from the scale and the keyboard, and sends output signal to the display, at real time rates which are compatible both with human keyboard manipulation and retention. Scale operation is divided into two portions which are called the communicate and compute cycles; the communicate cycle is usually repeated many times between compute cycles in order that real time information sensing and display operation be possible.