Stepping motor controller, scanning apparatus, and image forming apparatus

A scanning apparatus, comprising:

• a document scanning unit configured to scan a document;
• an image data reader configured to convert an image on the document into image data;
• a stepping motor configured to drive the document scanning unit to move;
• and
• a stepping motor controller for setting a driving current of the stepping motor, said stepping motor controller comprising:
• a storage unit configured to store a plurality of object values of the driving current;
• an accumulation unit configured to accumulate an amount of operation of the stepping motor;
• and
• a driving current setting unit configured to read out one of the object values corresponding to the amount of operation from the storage unit and to set the driving current to the one of the object values.

A scanning apparatus, comprising:

• a document scanning unit configured to scan a document;
• an image data reader configured to convert an image on the document into image data;
• a stepping motor configured to drive the document scanning unit to move;
• and
• a stepping motor controller for setting a driving current of the stepping motor, said stepping motor controller comprising:
• an accumulation unit configured to accumulate an amount of operation of the stepping motor;
• and
• a driving current setting unit configured to, when the amount of operation is greater than a predetermined value, determine a critical out-of-step current of the stepping motor by changing in increments the driving current of the stepping motor, and set the critical out-of-step current with a predetermined margin added thereto as an object driving current of the stepping motor.

An image forming apparatus, comprising:

• an image forming device that irradiates a laser beam to a photoconductor to form a static latent image thereon, develops the static latent image, and transfers the developed static latent image to paper;
• a stepping motor that drives a machinery portion of the image forming device to make mechanical motions;
• and
• a stepping motor controller for setting a driving current of the stepping motor, said stepping motor controller comprising:
• a storage unit configured to store a plurality of object values of the driving current;
• an accumulation unit configured to accumulate an amount of operation of the stepping motor;
• and
• a driving current setting unit configured to read out one of the object values corresponding to the amount of operation from the storage unit and to set the driving current to the one of the object values.

An image forming apparatus, comprising:

• an image forming device that irradiates a laser beam to a photoconductor to form a static latent image thereon, develops the static latent image, and transfers the developed static latent image to paper;
• a stepping motor that drives a machinery portion of the image forming device to make mechanical motions;
• and
• a stepping motor controller for setting a driving current of the stepping motor, said stepping motor controller comprising:
• an accumulation unit configured to accumulate an amount of operation of the stepping motor;
• and
• a driving current setting unit configured to, when the amount of operation is greater than a predetermined value, determine a critical out-of-step current of the stepping motor by changing in increments the driving current of the stepping motor, and set the critical out-of-step current with a predetermined margin added thereto as an object driving current of the stepping motor.

A stepping motor controller for setting a driving current of a stepping motor, comprising:

• storage means for storing a plurality of object values of the driving current;
• accumulation means for accumulating an amount of operation of the stepping motor;
• and
• driving current setting means for reading out one of the object values corresponding to the amount of operation from the storage means and setting the driving current to the one of the object values.