Collapsible picture frame

Claim 1

A collapsible display frame consisting of a one-piece flat blank of flexible, stiff sheet material, having cut-out portions, one at each corner of the blank, said blank having: a. a right parallelogram central panel defined by four first fold lines; b. four, right parallelogram wall panels, each integrally connected to said central panel, one side of each said wall panel being provided by one of said first fold lines, the side of each said wall panel opposite said one side being provided by a second fold line, and the other two sides of each said wall panel being provided by edges of said blank defining part of a said cut-out portion; c. four trapezoidal outer panels, each integrally connected to a said wall panel, the shorter base of each trapezoidal panel being provided by a said second fold line and the longer, parallel base of each trapezoidal panel being provided by an outermost edge of the blank; d. each pair of adjacent trapezoidal panels having means in the adjacent non-parallel sides thereof for locking said adjacent panels together when the blank is erected and forming a corner of the frame; said locking means having: i. a first large tab projecting from one of said adjacent nonparallel sides of said pair of adjacent trapezoidal panels and a pair of first notches disposed on either side of said tab with the openings of said notches facing away from each other; and ii. slot means in the other of said adjacent non-parallel sides of said pair of adjacent trapezoidal panels, said slot means comprising a pair of notched locking tabs immediately adjacent each end of said other non-parallel side and projecting therefrom, the notches in said notched locking tabs being spaced apart with their openings facing each other, said locking tabs defining therebetween a cut-out area forming part of a said cut-out portion, the cut-out area having an entrance slightly smaller than the length of the first large tab, the slot means being effective to lock both ends of said first large tab between said Locking tabs with the notches of said first large tab mating with the notches of said locking tab; e. adjacent non-parallel sides of two adjacent trapezoidal panels together with adjacent said other two sides of adjacent wall panels defining a said cut-out portion at each corner of the blank; and f. the first and second fold-lines being effective, when said blank is erected, to enable each wall panel to be substantially perpendicular to said central panel and to enable each trapezoidal panel to extend away from said central panel transverse to its connected wall panel.