Shutter mechanism including stepping motor control apparatus with upper and lower limit stopping position control

A stepping motor control apparatus for controlling upper and lower limit stopping positions of a stepping motor, comprising:

• a microcomputer including a memory for storing upper and lower limit motor stopping position data;
• a load magnitude detector circuit for detecting an increase in a load at the stepping motor and for inputting a signal indicative thereof to the microcomputer;
• and
• a current driver for causing a drive current to be supplied to the stepping motor, wherein
• the microcomputer is further for controlling the current driver to enable the current driver to selectively start and stop supplying of the drive current to the stepping motor based on the stored upper and lower limit motor stopping position data in response to receiving the signal indicative of the increase in the load at the stepping motor from the load magnitude detector circuit.

A stepping motor control apparatus for controlling bi-directional first and second stopping positions of an object moved by a stepping motor, comprising:

• a microcomputer including a memory for storing first and second stopping position data;
• a load magnitude detector circuit for detecting an increase in a load at the stepping motor and for inputting a signal indicative thereof to the microcomputer;
• a current driver for causing a drive current to be supplied to the stepping motor, wherein
• the microcomputer is further for controlling the current driver to selectively start and stop supplying of the drive current to the stepping motor based on the stored first and second stopping position data and on the signal indicative of the increase in the load at the stepping motor from the load magnitude detector circuit.