Stepping motor driving apparatus and image forming apparatus having such driving apparatus

A stepping motor driving controlling apparatus for effecting driving by switching phase exciting of exciting electrical current supplied to an exciting coil of a stepping motor whenever a driving signal is applied to a motor drive circuit, comprising:

• measuring means for measuring a change in electrical current value flowing through the exciting coil in a one phase exciting area of the stepping motor for a predetermined time period set by a timer;
• memory means for storing a measurement result of the change in the electrical current value obtained by measurement of said measuring means during the predetermined time period;
• comparing means for comparing the measurement result stored in said memory means with a threshold value;
• and
• generating means for generating a signal of loss of synchronism when the stored measurement result is greater than the threshold value.

A stepping motor driving controlling apparatus for supplying electrical current to a stepping motor rotating by successively switching phases of the stepping motor under constant electrical current chopper control, comprising:

• motor driving means for supplying the electrical current to the stepping motor under the constant electrical current chopper control;
• measuring means for measuring the electrical current value flowing through the stepping motor in said motor driving means;
• timer means for measuring a predetermined time;
• control means for emitting a measurement command to said measuring means at predetermined time intervals previously set by said timer means and for reading an electrical current value obtained by measurement of said measuring means;
• memory means for storing the electrical current value read by said control means;
• calculating means for calculating an electrical current increasing ratio at the predetermined time intervals by using the electrical current value stored in said memory means;
• comparing means for comparing the electrical current increasing ratio obtained by said calculating means with a threshold value;
• and
• generating means for generating a loss of synchronism signal when the electrical current increasing ratio is greater than the threshold value in said comparing means.

A stepping motor driving controlling apparatus for supplying electrical current to a stepping motor rotating by successively switching phases of the stepping motor under constant electrical current chopper control, comprising:

• motor driving means for supplying the electrical current to the stepping motor under the constant electrical current chopper control;
• measuring means for measuring the electrical current value flowing through the stepping motor in said motor driving means;
• timer means for measuring a predetermined time;
• control means for emitting a measurement command to said measuring means at predetermined time intervals previously set by said timer means and for reading an electrical current value obtained by measurement of said measuring means;
• memory means for storing the electrical current value obtained by said control means;
• calculating means for calculating an electrical current:
• increasing ratio at the predetermined time intervals by using the electrical current value stored in said memory means;
• first comparing means for comparing the electrical current increasing ratio obtained by said calculating means with a threshold value;
• count means counting the number that the electrical current increasing ratio exceeds the threshold value continuously in said first comparing means;
• second comparing means for comparing the number counted by said count means with a reference number;
• and
• generating means for generating a loss of synchronism signal when the number counted by said count means exceeds the reference number in said second comparing means.

A stepping motor driving controlling method for effecting driving by switching phase exciting of exciting electrical current supplied to an exciting coil of a stepping motor whenever a driving signal is applied to a motor drive circuit, comprising:

• a measuring step of measuring a change in an electrical current value flowing through the exciting coil in a one phase exciting area of the stepping motor for a predetermined time period set by a timer;
• a storing step of storing a measurement result of the change in the electrical current value obtained in said measuring step during the predetermined time period;
• a comparing step of comparing the measurement result stored in said storing step with a threshold value;
• and
• a generating step of generating a signal of loss of synchronism when the stored measurement result is greater than the threshold value.

A stepping motor driving controlling method for supplying electrical current to a stepping motor rotating by successively switching phases of the stepping motor under constant electrical current chopper control, comprising:

• a supplying step of supplying the electrical current to the stepping motor under the constant electrical current chopper control;
• a measuring step of measuring the electrical current value flowing through the stepping motor;
• an emitting step of emitting a measurement command at predetermined time intervals;
• a reading step of reading an electrical current value measured in accordance with the measurement command in said measuring step;
• a storing step of storing the electrical current value read in said reading step;
• a calculating step of calculating an electrical current increasing ratio at the predetermined time intervals by using the electrical current value stored in said storing step;
• a comparing step of comparing the electrical current increasing ratio obtained in said calculating step with a threshold value;
• and
• a generating step of generating a loss of synchronism signal when the electrical current increasing ratio is greater than threshold value in said comparing step.

A stepping motor driving controlling method for supplying electrical current to a stepping motor rotating by successively switching phases of the stepping motor under constant electrical current chopper control, comprising:

• a supplying step of supplying the electrical current to the stepping motor under the constant electrical current chopper control;
• a measuring step of measuring the electrical current value flowing through the stepping motor;
• an emitting step of a measurement command at predetermined time intervals;
• a reading step of reading an electrical current value measured in accordance with the measurement command emitted in said emitting step;
• a calculating step of calculating an electrical current increasing ratio at the predetermined time intervals by using the electrical current value stored in said storing step;
• a first comparing step of comparing the electrical current increasing ratio obtained in said calculating step with a threshold value;
• a counting step of counting the number that the electrical current increasing ratio exceeds the threshold value continuously in said first comparing step;
• a second comparing step of comparing the number counted in said counting step with a reference number;
• and
• a generating step of generating a loss of synchronism signal when the number counted in said counting step exceeds the reference number in said second comparing step.