System for driving and controlling an open-area shield

A system for driving and controlling an open-area shield, comprising:

• an open-area frame member having an opening;
• an open-area shielding member defining an open area together with said open-area frame member and made movable for shielding said open area;
• drive means for driving said open-area shielding member;
• closing drive instructing means for producing a closing drive instruction to drive said open-area shielding member in a direction to reduce said open area;
• a detection electrode disposed in at least one portion of the substantial peripheral edge of said open area;
• electrostatic capacity detecting means for detecting the electrostatic capacity of said detection electrode;
• obstruction setting means for setting the presence of an obstruction in said open area in accordance with the electrostatic capacity detected by said electrostatic capacity detecting means;
• and
• energization control means for energizing said drive means to close said open-area shielding member in response to said closing drive instruction of said closing drive instruction means and for deenergizing said drive means when said obstruction setting means sets the presence of an obstruction;
• wherein said obstruction setting means sets the presence of an obstruction if the increasing rate of said electrostatic capacity per unit time exceeds a predetermined value causing said energization control means to de-energize said drive means, and the absence of an obstruction if said electrostatic capacity decreases, causing said energization control means to resume energization of said drive means after de-energization.