Blocking device for card or voucher readers designed for public use

Claim 1

In a device for blocking a slot formed in a wall separating two mediums and for permitting the free passage, in an open position, from one medium to the other, of a flat object, said device comprising a cylindrical element, means for supporting said element for rotating about its axis in front of said slot, an elongated radial opening extending through said element, means for rotating said element about its axis and means for stopping rotation of said element in predetermined angularly spaced positions, the improvement comprising a guide block including a cylindrical opening receiving said cylindrical element and supporting said cylindrical element for rotation about its axis, said block including a passage extending therethrough from said wall and intersecting said element for alignment with the radial opening of said element, and wherein said means for rotating said cylindrical element comprises means for rotating said element in a single direction from position to position and through 360°; whereby, a cord attached to the card for effecting fraudulent passage of the flat object first in one direction through said passage from one side of the block to the other and through said aligned radial opening of said element wherein said opening of said element is aligned with said passage of said block and for subsequent passage in the opposite direction, wraps itself about the cylinder and blocks the passage to prevent the card from being recovered in an unauthorized fashion.