Safety device for hospital beds employing electric current

Abstract

A safety circuit employing pulse transformers to protect hospitalized patients from high-voltage currents. The circuit finds use on switches controlling the operation of a hospital bed's motors, as well as on other types of controls. The pulse transformers prevent the motor's high-voltage levels from reaching the switching devices contacted by the patient. To operate the bed, the circuit provides a high frequency, low-voltage current to the pulse transformer which transfers it to a controlling triac. When in receipt of this current, the triac assumes a conducting state. A separate frequency generator provides this high-frequency current. The circuit may employ electronic devices to control the performance of the bed or other load. CMOS components operate satisfactorily with nonregulated voltages, produce delay periods with small capacitances, and consume little power. The CMOS components may, however, require a buffer in order to provide the pulse transformers with sufficient current. Furthermore, the circuit may require protecting diodes to prevent current spikes produced at the motors from reaching the CMOS components.