Multichannel programmable band comparator for apparatus used in cardiac surgery

Claim 1

A multichannel programmable band comparators for use in cardiac surgery, comprising a plurality of transducers adapted to provide signals indicative of physical parameters of a patient, a multiplexer connected to said transducers to multiplex the signals thereof; an analog-to-digital converter connected to said multiplexer to receive the multiplexed signals therefrom and to convert such signals into digital form; an oscillator which generates an external clock timing signal which is conveyed to said analog-to-digital converter; a memory block disposed to receive and store digital form information representing upper limit and lower limit values of said parameter; a comparator block arranged to compare signals from said analog-to-digital converter with said upper limit and lower limit values obtained from said memory, a first counter that supplies the address of a parameter channel under examination to both said multiplexer and said memory to ensure correspondence between said analog-to-digital converter signals and upper limit and lower limit signals; a control logic block connected to an output of said oscillator and to an output of said analog-to-digital converter, and alarm means connected to the output of said comparator block, said alarm means comprising a demultiplexer which receives said address from the first counter and from which alarm signals are supplied, and an alarm device connected to said demultiplexer to produce a visual and acoustic alarm when any of said signals from said analog-to-digital converter is outside said upper limit and lower limit values, and wherein said analog to digital converter supplies an end of conversion signal EOC, a control logic block connected to an output of said oscillator and to on output of said analog-to-digital converter in which said end of conversion signal EOC is processed together with a timing signal provided by said oscillator and which generates an enabling signal DEN for said demultiplexer to pass information on to said alarm device only when said end of conversion signal EOC has been received by said logic block.