Patent ID: 7132814

Claim:
A method of calculating a correction value, comprising the steps of: preparing a printer that is provided with a motor, a PID control system for controlling said motor, and a memory for storing a correction value, said printer being configured to calculate a value of a current flowing through said motor based on said correction value and an output value of an integral element of said PID control system; obtaining in advance a relationship, for when a property of a motor fluctuates, between a correction value and a sum of an output value of the integral element when a motor is driven at a first velocity and an output value of the integral element when the motor is driven at a second velocity; driving said motor of said printer at the first velocity and measuring an output value of said integral element at that velocity; driving said motor of said printer at the second velocity and measuring an output value of said integral element at that velocity; and determining said correction value to be stored in said memory based on said relationship and a sum of the two output values that have been measured.