Handheld digital gemstone measurement apparatus

摘要

A digital gemstone measurement device includes a first caliper jaw fixed to a housing, a second caliper jaw movable relative to the first caliper jaw, an encoding wheel that rotates in response to linear motion of the second caliper jaw, a photosensor for sensing rotation of the encoding wheel and a microcomputer responsive to photosensor output signals for calculating the weight of a gemstone. A slotted rotary encoding wheel provides measurement resolution on the order of 0.01 millimeter. A spring-loaded pneumatic dashpot urges the caliper jaws together relatively slowly so as to avoid snap-action. The gemstone shape is selected from a list, and the weight is calculated from a predetermined formula corresponding to the shape. The device is handheld and includes a keypad for controlling operation and an alphanumeric display for readout of measurement results.