Patent attributes
A variable shape frame having a polygonal shape includes: extendable arms forming each side of a polygonal frame; and corner members located at at least two of the corners of the polygon. Each of the extendable arms includes cross units each formed by two rigid members in an X-shape and pivotally coupled by a middle coupling shaft, and an end coupling portion pivotally coupling ends of adjacent ones of the cross units. The end coupling portion includes inner end coupling shafts and outer end coupling shafts. Adjacent two of the extendable arms are pivotally coupled by a common one of the inner end coupling shafts at every corner of the polygon. The corner member includes a first guide portion linearly guiding the inner end coupling shafts of the first extendable arm, and a second guide portion linearly guiding the inner end coupling shafts of the second extendable arm.
