Patent ID: 8161868

Claim:
A rigid filter for capsules suitable for extracting beverages, comprising a substantially flat body having a plurality of through filtering holes, which are sized so as to block passage of solid particles and allow passage of brewed water or beverage, said holes having a substantially symmetrical shape with respect to a middle plane of the flat body, so that the filter can be inserted into a capsule without taking care of an orientation of such holes with respect to a powdered substance within the capsule, said holes having a double-frustum shape, a diameter of each hole in a middle region thereof being narrower than a diameter of the hole at face regions of the flat body, so that a cross-section of each hole symmetrically diverges from the middle region towards the face regions, wherein a divergence angle from the middle region to any one of the face regions of each hole is between 1° and 30° and the diameter of the middle region of the hole is between 0.1 mm and 1.0 mm.