Abstract: The apparatus is utilized to detect disturbance created in an opening by objects even when the objects do not move so that they cannot be detected by a motion detector. The apparatus includes a transmitter-receiver apparatus provided at the opening comprising a plurality of arrays, each of which comprises a receiver and a plurality of transmitters. Because divergent beams are emitted by the transmitters, which preferably consist of infrared-emitting diodes, the transmitters and the associated receiver can be arranged to define a triangle in space so that the space of the opening can be completely covered by a plurality of transmitter-receiver arrays. By means of a cyclic signal sequence it is ensured that a signal which has been transmitted is checked in the receiver whether it belongs to the correct transmitter.

Abstract: A panel-like structural component for gates, doors, facings or the like includes a main wall and a frame surrounding the main wall. The frame is composed of sectional members with hollow rectangular cross sections whose inner walls facing the inside of the frame have at least one groove at least in the longitudinal direction of the matter. The grooves of all longitudinal members open into each other and form a continuous peripheral groove into which a panel forming the main wall is inserted at its edges. The grooves are also used to join two sectional members together: the groove, which becomes wider toward its interior, is engaged at one of the sectional members with a projection formed on a connecting piece fastened to the other sectional member. The connecting piece is made up of a segment of another sectional member. The structural component can be produced with little labor and material; it is stable and lightweight and can be disassembled to simplify repair in the event it is damaged.

Abstract: A folding gate comprises two rectangular segments connected for articulation by hinges, said first segment being supported directly by a gate wing bearing. Said second segment includes a panel and a carrier structure to support the weight of the panel, said carrier structure comprises a pivot arm which is disposed at the upper edge of the second segment and from which the panel is suspended, wherein the pivot arm is connected by its one end to a carrier structure of the first segment in articulated fashion such that the pivot arm is movable not only about a vertical axis but to a limited extent also about a horizontal axis with respect to the first segment, and wherein the other end of the pivot arm is guided horizontally and supported vertically at a glide track arrangement by means of a guide roller. By this structure any impact hitting the panel of the second segment practically is not transmitted to the first segment.