| 摘要 |
The equipment comprises a power driver (PWR) which supplies the head (T), which in turn is supplied at a voltage (V) made proportional to the nominal voltage of the said head and which is provided with a sensor (Rs) which detects the magnetisation current of the head. This sensor is in turn connected to a control circuit (CNT) which drives the power stage (PWR) and which receives activation commands from the outside, these commands corresponding to the direction of flow of the current in the head. When the said sensor (Rs) detects that the magnetisation current of the head has reached the nominal value, it signals this event to the control unit (CNT) which proceeds to divide the flow of the said current by the opening and reclosing at suitable frequency of the switch or switches which in the power stage (PWR) cause the said current to flow in the direction determined by the external command in the said control unit, in such a way that the said current is kept at a substantially constant value. The cancellation of the magnetisation current, when its direction has to be changed, is very rapid as a result of the known design of the equipment of the bridge type with recirculation diodes. <IMAGE> |
