Driving circuit for a magnetic head and magnetic recording apparatus

Abstract

A magnetic head driving circuit includes a main driving circuit symmetrical with respect to a centered recording coil, and at least two pairs of adding circuits, each pair including a positive pulse adding circuit and a negative pulse superposed circuit symmetrical with respect to the centered coil. And, by reversing the direction of the magnetic head coil current, at least one of the adding circuits is made to operate and make it as a magnetic head driving circuit for adding a potential equal to or higher than the power supply, thereby to drive as a sub-driving circuit arranged symmetrically with respect to the centered coil, which promotes the reversal of the magnetic head coil current, and which drives stably with a central potential of the coil at about the disk potential.

1 . A differential amplifier comprising: 
 an inductive load;    a main driving circuit for making a current flow in a positive direction or a negative direction through said inductive load; and    a sub-driving circuit for applying a voltage symmetrical with respect to the centered inductive load by superposing a pair of pulse voltages corresponding to a change-over direction at both terminals of said inductive load,    wherein said sub-driving circuit is configured to superpose said pair of pulse voltages so that a potential difference equal to or greater than a power supply is applied to said both terminals of said inductive load.    
   
   
       2 . The differential amplifier according to  claim 1 , 
 wherein resistors are symmetrically connected between said inductive load and said main driving circuit, and    wherein said sub-driving circuit is connected to a connection node between one of said resistors and said inductive load, and to a connection mode between the other of said resistors and said inductive load.    
   
   
       3 . The differential amplifier according to  claim 1 , 
 wherein said sub-driving circuit includes at least two pairs of circuits, each pair including a positive pulse adding circuit and a negative pulse adding circuit.    
   
   
       4 . The differential amplifier according to  claim 1 , 
 wherein said sub-driving circuit has a function to change a pulse voltage valve to be adding to said inductive load in accordance with a current value made to flow by said main driving circuit.