Patent ID: 6448753
Filing Date: 2002-09-10
Classification: G01R

Abstract:
digital meter for measuring alternating current, comprising:a housing, a voltage magnet disposed in said housing and positioned opposing said electric current magnet to induce a magnetic field there above; a signal line; a metal rotary disk, which has two opposing side face and a through hole provided at a periphery edge thereof, comprising a shaft pivotally mounted at a center of said metal rotary disk, wherein said metal rotary disk is coaxially and rotatably mounted over said voltage magnet, wherein said metal rotary disk is induced by said magnetic field to rotate with said shaft simultaneously about an axis of said shaft and a circular moving path of said through hole is defined when said through hole rotates with said metal rotary disk; a light-emitting element, which is fastened to face one of said side face of said metal rotary disk inside said housing and extended to position adjacent to said periphery edge of said metal rotary disk and define a distance between said light-emitting element and said periphery edge of said metal rotary disk, wherein a light signal is emitted from said light-emitting element and projected on said moving path of said through hole of said metal rotary disk in such a manner that said light signal is capable of passing through said through hole when said through hole is rotated to a position right above said light-emitting element; and a light-sensing element, which is fastened to face another said side face of said metal rotary disk inside said housing and extended to position adjacent to said periphery edge of said metal rotary disk and define a distance between said light-sensing element and said periphery edge of said metal rotary disk, wherein said light-sensing element, which is connected with said signal line for transmitting digital signals, is also positioned opposing to said light-emitting element in such a manner that said light signal emitted through said through hole is capable of being received and sensed by said light-sensing element, wherein when said metal rotary disk is induced to rotate by said magnetic field of said voltage magnet, said light signal emitted from said light emitting end of said light-emitting element is projected continuously on said periphery edge of said metal rotary disk, wherein when said through hole of said metal rotary disk in rotation arrives at said position where said light emitting end is located, said light signal emitted from said light-emitting element is received by said light-sensing element via said through hole of said metal rotary disk, wherein when said metal rotary disk completes one revolution, said light signal is received once by said light-sensing element, wherein as long as said metal rotary disk rotates, said light-sensing element intermittently receives said light signal which is outputted via said signal line; and a signal conversion display receiving and converting said light signal to a numerical value of power consumption.