Digital servo control unit and laser machining apparatus

A digital servo control unit comprising:

• a processor for performing a servo control process for every predetermined sampling period;
• a D/A converter for converting a control input signal into an analog signal, the control input signal being calculated by the servo control process;
• a current control circuit for controlling a driving current to be supplied to an actuator in accordance with the D/A-converted control input signal;
• a filter acting on the analog signal output by the D/A converter;
• and
• a stabilizing compensation means for compensating a phase delay caused by the filter;
• wherein an output signal of the filter is input to the current control circuit as a current command signal, and
• wherein the filter is a notch filter having a cut-off frequency which is equal to a sampling frequency.

A digital servo control unit comprising:

• a processor for performing a servo control process for every predetermined sampling period;
• a D/A converter for converting a control input signal into an analog signal, the control input signal being calculated by the servo control process;
• a current control circuit for controlling a driving current to be supplied to an actuator in accordance with the D/A-converted control input signal;
• a filter acting on the analog signal output by the D/A converter;
• and
• a stabilizing compensation means for compensating a phase delay caused by the filter;
• wherein an output signal of the filter is input to the current control circuit as a current command signal, and
• wherein the filter is a notch filter having a cut-off frequency which is equal to an integral multiple of a Nyquist frequency.

A laser machining apparatus comprising:

• a digital servo control unit comprising a processor for performing a servo control process for every predetermined sampling period;
• a D/A converter for converting a control input signal into an analog signal, the control input signal being calculated by the servo control process;
• a current control circuit for controlling a driving current to be supplied to an actuator in accordance with the D/A-converted control input signal;
• a filter acting on the analog signal output by the D/A converter;
• and a stabilizing compensation means for compensating a phase delay caused by the filter;
• wherein an output signal of the filter is input to the current control circuit as a current command signal;
• an actuator to be driven by the digital servo control unit;
• and
• a steerable mirror to be positioned by the actuator;
• wherein an angle of a laser beam reflected by the steerable mirror is controlled to machine a predetermined position of a to-be-machined product, and
• wherein the filter is a low pass filter having a cut-off frequency which is lower than a sampling frequency.

A laser machining apparatus comprising:

• a digital servo control unit comprising a processor for performing a servo control process for every predetermined sampling period;
• a D/A converter for converting a control input signal into an analog signal, the control input signal being calculated by the servo control process;
• a current control circuit for controlling a driving current to be supplied to an actuator in accordance with the D/A-converted control input signal;
• a filter acting on the analog signal output by the D/A converter;
• and a stabilizing compensation means for compensating a phase delay caused by the filter;
• wherein an output signal of the filter is input to the current control circuit as a current command signal;
• an actuator to be driven by the digital servo control unit;
• and
• a steerable mirror to be positioned by the actuator;
• wherein an angle of a laser beam reflected by the steerable mirror is controlled to machine a predetermined position of a to-be-machined product, and
• wherein the filter is a notch filter having a cut-off frequency which is equal to a sampling frequency.

A laser machining apparatus comprising:

• a digital servo control unit comprising a processor for performing a servo control process for every predetermined sampling period;
• a D/A converter for converting a control input signal into an analog signal, the control input signal being calculated by the servo control process;
• a current control circuit for controlling a driving current to be supplied to an actuator in accordance with the D/A-converted control input signal;
• a filter acting on the analog signal output by the D/A converter;
• and a stabilizing compensation means for compensating a phase delay caused by the filter;
• wherein an output signal of the filter is input to the current control circuit as a current command signal;
• an actuator to be driven by the digital servo control unit;
• and
• a steerable mirror to be positioned by the actuator;
• wherein an angle of a laser beam reflected by the steerable mirror is controlled to machine a predetermined position of a to-be-machined product, and
• wherein the filter is a notch filter having a cut-off frequency which is equal to an integral multiple of a Nyquist frequency.