Patent ID: 6750566
Filing Date: 2004-06-15
Classification: G06F

Abstract:
An electrical unit for plug-in connection to a base unit, said plug-in electrical unit comprising:non-isolated first and second control lines, signal lines, data lines, and address lines; first control lines and signal lines all isolated from an associated one of said non-isolated first control lines and said non-isolated signal lines when a first switching means connected between said isolated first control and signals lines and said non-isolated first control and signal lines is in an open condition; second control lines all isolated from an associated one of said non-isolated second control lines when a second switching means connected between said isolated and said non-isolated second control lines is in an open condition; address lines all isolated from an associated one of said non-isolated address lines when a third switching means connected between said isolated and non-isolated address lines is in an open condition; and data lines all isolated from an associated one of said non-isolated data lines when a fourth switching means connected between said isolated and said non-isolated data lines is in an open condition; said first switching means changing to a closed condition only when a power supply voltage in said plug-in electrical unit reaches a predetermined amplitude; said second switching means changing to a closed condition only when said non-isolated and said isolated first control lines are connected to each other and said plug-in electrical unit is plugged in to said base unit and identified as compatible with said base unit; and said third switching means and said fourth switching means both changing to a closed condition as needed under control of an associated one of said second control lines only when said non-isolated and said isolated second control lines are connected to each other.