Hand held instrument for measuring material lengths - is used in shops to calculate values of material sold by length

摘要

The instrument (1) has a small wheel (2) mounted on a free-running shaft (3). The wheel is positioned on a platform (6) at the front end of the (7) of the instrument. Each time the wheel rotates a magnetic element (4) embedded in the outer surface of the wheel is detected by a sensor (5). The output of the sensor is fed via a cable (10) to an electronic calculator and readout. At the other end of the instrument is an optical bar code reader (9). When a customer brings a length of material e.g. a piece of plastic extrusion (8) to the checkout, the cashier reads a bar code with one end of the instrument and then runs the wheel along the length. The value of item is then indicated on a display. variant of this instrument has the display and calculator built into the body of the hand held instrument rather than being a separate item.