Ultrasonic transmitter switching circuit

Claim 1

A circuit for producing high voltage output pulses to drive selected ones of a plurality of ultrasonic transducers comprising: a plurality of chargeable capacitor circuits each including a resistor and a capacitor connected in series; means for connecting each of said chargeable capacitor circuits to a different one of Said transducers; circuits source means providing voltages for charging the capacitor of each of said chargeable capacitor circuits through the resistor corresponding to each capacitor; means for rapidly discharging said chargeable capacitor circuits, said discharging means including: gated switch means including a gate-controlled rectifier; and asymmetrically conducting means for coupling each of said chargeable capacitor circuits in parallel to said gated switch means; said gate-controlled rectifier being operable to switch into a high current conducting state, thereby to discharge the capacitors of said chargeable capacitor circuits through said asymmetrically conducting coupling means; and means for selectively disabling one or more of said chargeable capacitor circuits, said selective disabling means including a plurality of gate-controlled switches respectively connected to the capacitors of said chargeable capacitor circuits, each of said gate-controlled switches being operable in a conducting state to divert said charging current and thereby to maintain the corresponding capacitor in a discharged inactive condition.