Patent Number 5,938,529

Reel type slot machine having stepper motor monitoring system

Issue Date: August 17, 1999
Inventors: Rodesch; Gregory L. (Oceanside, CA); Rodesch; Dale F. (San Diego, CA)
Appl. No.: 818850
Filed: March 17, 1997


A reel-type slot machine includes a microprocessor driven game control circuit for randomly determining a game result and three reel assemblies each including a symbol-bearing reel driven by a stepper motor for displaying the game results. The stepper motors each include a permanent magnet rotor and four stator windings which respond to quadrature phase motor drive signals generated by the game control circuit to incrementally rotate the reels. A reel motion monitoring circuit senses back EMF on each stator winding to generate an error signal which inhibits play in the event a motor fails to respond to an applied drive signal or a reel is moved by tampering.