1. Field of the Invention
This invention relates to a method of driving and controlling a stepping motor and, more particularly, to an intermittent-driving method which enables a stepping motor to be driven at a high speed and stopped at any desired position without any oscillation of the motor.
2. Description of the Prior Art
An example of positive casting control or deadbeat control, which has been known as a method of driving and controlling a stepping motor, is disclosed in Japanese Patent Laid-Open No. 36409/1977. This type of casting control enables a stepping motor to be rapidly stopped by utilizing an overshoot of the stepping motor, and it is effected in such a manner that application of pulses is temporarily stopped one step before a desired point to cause the motor to overshoot and the pulse of the remaining step is applied when the motor comes closest to the desired point. This positive casting control sets the shaft of the motor as shown in FIG. 3, so that the motor can be stopped without any oscillation.
However, if, as shown in FIG. 2, an object to be driven is connected to a stepping motor by a spring system 4 consisting of a spring and a damper and is driven by the stepping motor (for example, an exposure head is made to secondarily scan by using reels and synchronizing belts), the above-described method of positive casting control cannot stop the driven object without oscillation, resulting in the state shown in FIG. 4. As shown in FIG. 4 which shows the extent of movement of the driven object when the stepping motor is driven by a timing of 0, 1.2, 2.2, 6.5 ms, the driven object oscillates relative to a desired point in a range of .+-.3.5% even after 33 ms (1 idling) have passed.