Motor driving circuit

A motor driving circuit for generating sine wave signals for driving a step motor, comprising:

• memory means for storing sine wave data at respective addresses therein, said memory means having stored therein a plurality of data tables containing a plurality of sine wave data, each of said data tables having a respectively different amplitude value;
• address generator means for generating address signals having a plurality of bits for accessing corresponding addresses in said memory means for a predetermined portion of a frame in a vertical period;
• bit shifter means for bit-shifting said address signals from said address generator means and thereby setting a desired frequency;
• and
• means for reading the sine wave data stored at the accessed addresses in said memory means and for processing the read sine wave data so as to form sine wave driving signals having said desired frequency for driving the step motor.

A motor driving circuit for generating sine wave signals for driving a step motor, said circuit comprising:

• input means for receiving a predetermined number of horizontal sync pulses in each of a succession of frame periods;
• memory means for storing sine wave data at respective addresses therein;
• pulse removal means for removing a predetermined number of said horizontal sync pulses at substantially equal intervals during each of said frame periods so that the remaining number of said horizontal sync pulses per frame becomes a power product of 2;
• address generator means counting said remaining number of horizontal sync pulses for generating address signals accessing corresponding addresses in said memory means;
• and
• means for reading the sine wave data stored at the accessed addresses in said memory means and for processing the read sine wave data so as to form sine wave signals for driving the step motor.

A motor driving circuit for generating sine wave signals for driving a step motor, said circuit comprising:

• input means for receiving a predetermined number of clock pulses in each of a succession of frame periods;
• memory means for storing sine wave data at respective addresses therein corresponding to a quarter frame period;
• address generator means counting said predetermined number of said clock pulses for generating address signals accessing in a predetermined order corresponding addresses in said memory means;
• inverter means for inverting the order in which said addresses are accessed in each of the quarter frame periods;
• and
• means for reading the sine wave data stored at the accessed addresses in said memory means in the order set forth by said inverter means and for processing the read sine wave data so as to form sine wave signals for driving the step motor.

A motor driving circuit for generating sine wave signals for driving a step motor, said circuit comprising:

• input means for receiving a predetermined number of clock pulses having time durations of alternating high level and low level states in each of a succession of frame periods;
• memory means for storing a plurality of sine wave data having respective amplitudes at respective addresses therein corresponding to a quarter frame period;
• address generator means counting said predetermined number of said clock pulses for generating generating address signals accessing in a predetermined order corresponding addresses in said memory means;
• inverter means for inverting the order in which said addresses are accessed during each of the quarter frame periods in accordance with the state of the current clock pulse;
• and
• means for reading the sine wave data stored at the accessed addresses in said memory means in the order set forth by said inverter means and for processing the read sine wave data so as to form sine wave signals having respective phases for supply to the step motor so as to drive the same.

A motor driving circuit for generating sine wave signals for driving a step motor, said circuit comprising:

• memory means for storing a plurality of sine wave data having respective amplitudes in respective addresses therein;
• address generator means for generating address signals accessing corresponding addresses in said memory means;
• and
• means for reading the sine wave data stored at the accessed addresses in said memory means and for processing the read sine wave data so as to form sine wave signals for driving the step motor, sine wave data having a relatively large amplitude being read out from said memory means at the start of rotation of said step motor and, after said step motor has started rotating, sine wave data of smaller amplitude are read out from said memory means when a predetermined phase angle of the sine wave data is obtained.