Printer and motor having a balanced buck drive

A method for driving a line printer having a plurality of hammers on a hammerbank for printing on an underlying media comprising:

• providing a motor with multiple coils connected to said hammerbank for movement of said hammerbank in response to said motor;
• providing a state machine to control the current in said coils;
• driving one of said coils with a current at startup of the motor;
• rotating said motor to a known position;
• driving the motor through a subsequent coil;
• detecting the position of the motor while at the same time linking the position of the motor to the position of the hammerbank;
• energizing said coils for initially driving them positively from a reference level to an upper reference level;
• allowing the current in said coils when driven to said upper reference level to decay to an intermediate reference level;
• driving said coils negatively from said intermediate reference level;
• and,
• allowing the current in said coils to further decay after driving said coil negatively.

A motor for driving a line printer with controls comprising:

• a motor having a plurality of coils;
• H bridge means having transistors connected to said coils for driving said coils;
• control means for turning on said transistors to cause negative and positive flow through the H bridge means connected to said coils;
• means for causing positive flow of current from a reference level to an upper reference level through said coils;
• means to allow decay of current within said coils from said upper reference level to an intermediate reference level;
• means for driving said coils with a negative current from said intermediate reference level to a second intermediate reference level;
• means for allowing current within said coils to decay from said second intermediate reference level to the initial reference level;
• and
• a state machine for controlling the positive and negative current to said coils.

A method of driving a dot matrix printer comprising:

• providing a plurality of hammers forming in part a hammerbank;
• providing means for releasing said hammers for printing on a print media;
• counterbalancing said hammerbank by a counterbalance in adjacent parallel relationship with said hammerbank;
• providing a motor having coils for driving said hammerbank and said counterbalance;
• energizing said coils at an initial reference level with current to an upper reference level;
• allowing the current in said coils to decay from said upper reference level to an intermediate reference level;
• driving the current negatively in said coils from said intermediate reference level to a second intermediate reference level;
• allowing the current in said coils to decay to said initial reference level;
• and
• providing a state machine that controls the current to said coils with respect to given reference levels.

The method of driving a D.C. motor having a coil comprising:

• driving said coil positively at an initial reference level to an upper reference level;
• allowing the current in said coil to decay from said upper reference level to a first intermediate reference level;
• driving said coil negatively from said first intermediate reference level to a second intermediate reference level;
• allowing the current in said coil to decay from said second intermediate reference level to a lower reference level;
• and,
• controlling the positive and negative current to said coil by a state machine.