| 摘要 |
A system for testing the dental pulp of a tooth by electrically stimulating the pulp with a pulsating signal having a continuously increasing amplitude. The system includes a probe having an electrode adapted to the tooth, and a contact device for sensing when the probe electrode makes contact with the tooth and for increasing the amplitude of the stimulus from an initial value. The intensity continues to increase as long as the probe electrode is in contact with the tooth. The electrical stimulus may be generated by a voltage controlled pulse generator driving the primary of a transformer, with the secondary of the transformer connected to the electrode probe. The transformer has a relatively low cutoff frequency so that the amplitude of the signal across the secondary is proportional to the pulse width of the incoming signal. Consequently, as the control voltage to the voltage control pulse generator increases, the amplitude of the pulses across the secondary also increases. The voltage control pulse generator also drives a counter, and the output of the counter is indicated on a digital display. Since the amplitude of the control voltage is a function of the number of pulses generated by the pulse generator, the output of the counter indicates the amplitude of the electrical stimulus. Alternatively, a ramp generator is connected to one end of the primary and the other end of the primary is periodically grounded responsive to fixed frequency, fixed duration pulses from the output of an oscillator. |
