| 摘要 |
PURPOSE: To prevent a feeling of stimulus from occurring on a patient by providing a current safety circuit having a real current value detector and a current threshold value generator, setting a current threshold value so that the current safety circuit can give no response when a patient impedance is small and the increase of a current from zero is a little. CONSTITUTION: A microprocessor 1 generates a stimulus current pulse waveform having suitable strength through a pulse waveform/strength card 5. The real value of the current is detected by a resistor 10 and supplied through an analog/ digital converter 11 to the microprocessor 1. The microprocessor 1 compares the supplied current threshold value with the real value and when the real value exceeds the current threshold value, a current cutoff signal is applied to a lead wire 13. In that case, when a high voltage is set with the high patient impedance, the current threshold value is selected so as not to give any response yet from the safety circuit when a current initial value is detected and when the voltage is already set and a stimulus current electrode is applied, the current threshold value is selected so as not to exceed the stimulus threshold value of a patient when the stimulus current is lower than the current threshold value. |
