BLACKBOARD Russian patent published in 1997 - IPC

FIELD: technical means of training and is used to write information by chalk. SUBSTANCE: aim is to decrease weight, cost and to improve ecological features of blackboard. Blackboard is made of two metal (aluminum) sheets and corrugated nonmetallic material is made in the form of filler, mainly, pressboard. Filler is made as corrugations of Z-shaped form and along perimeter frame is mounted between sheets. Perimeter also has decorating framing of $$$-shaped form. EFFECT: decreased weight, cost and improved ecological features of blackboard. 3 cl, 3 dwg