Abstract: A tape driving apparatus is disclosed which is operable to shift all of tapes simultaneously so as to position items recorded on the tapes in a predetermined position or to record informations on the tapes. The tape driving apparatus includes a plurality of pairs of first and second rollers and associated tapes, the first and second rollers having a polygonal cross section, each tape being wound on the corresponding first roller from its one end with one face thereof inside and on the corresponding second roller from the other end thereof with the other face thereof inside.

Abstract: The porosity of a strip of material is continuously computed by causing air to be drawn through the material as the strip moves across a perforated head situated atop a chamber in which the pressure is reduced by suction. In one embodiment, the reduced pressure is held substantially constant while the amount of air drawn through the chamber is measured and the porosity is determined by a computer whose inputs include the measured volume of air flow through the chamber and the speed at which the strip moves across the head, in addition to other inputs. In another embodiment, the volume of air flowing through the chamber is held substantially constant while the pressure in the chamber is measured and used as an input to the computer. In both embodiments, the speed at which the strip moves across the head is employed as a factor in the porosity computation.

Abstract: The invention relates to a measuring head for measuring the porosity of a moving strip of porous material. The measuring chamber of the measuring head is covered by a measuring plate in which measuring openings are provided. For porosity measurement, air is sucked in through the porous strip and the measuring openings into the measuring chamber. The amount of air flowing into the measuring chamber is measured by a measuring arrangement connected to the measuring air connector and serves as a measure of the porosity of the strip. The measuring plate is surrounded by a guide plate which partially overlaps a blowing ring. The guide plate and blowing ring together form a blowing slot surrounding the measuring plate, the blow-out opening of which is directed outwardly and tangentially to the lower surface of the moving strip. The necessary blowing air is introduced via a connector into an annular channel, which is formed from a semi-circular groove in the blowing ring and merges into the blowing slot.