An object counter includes a feeding funnel having a frustroconical section, the narrow end of which is coupled to a substantially vertical feeding channel having a substantially rectangular cross section. A pair of linear optical sensor arrays are arranged along adjacent orthogonal sides of...http://www.google.com.hk/patents/US5768327?utm_source=gb-gplus-share專利 US5768327 - Method and apparatus for optically counting discrete objects
