Abstract: A playback apparatus for a storage disc permits improved damping of vibration of the storage disc normal to the plane of the disc. The playback apparatus includes a first disc and a second disc, where the storage disc can be positioned between the first disc and the second disc. A predetermined distance is provided between the storage disc and the first disc within a predetermined area. The area and the distance are selected so that when there is vibration of the playback at apparatus approximately normal to the plane of the disc with an acceleration not exceeding a predetermined value, there results an amplitude of a resulting vibration of an outside edge of the storage disc in relation to a mid point of the storage disc which is below a predetermined value.

Abstract: A method is proposed which serves to control the focusing of a light beam, aimed at a rotating recording medium (25) for reading data, of a scanner (15, 20) onto the recording medium (25) and the guidance of the light beam along the data tracks of the recording medium (25), each by means of a respective control circuit. The scanner (15, 20) and the recording medium (25) are mounted on a fundamental substrate (10) in at least one housing (1), and the at least one housing (1), together with the fundamental substrate (10), the scanner (15, 20) and the recording medium (25), forms a coupled mechanical oscillator, which is vibrated as a function of a vibration spectrum (75); the scanner (15, 20) is accelerated by the vibration and a relative motion of the recording medium (25) with respect to the scanner (15, 20) is effected, and the amplitudes of the relative motion and the accelerations have a frequency response.

Abstract: Proposed is a compensation scale (10) in which at least one acceleration sensor (24, 25) is disposed at a movable component (14) of the scale (10) and puts out a signal to a correction signal processing arrangement (50) which determines at least one correction signal (53, 54, 56) for influencing the measuring result that appears at the output (43) as a measure for the weight or the mass (m) of the load (15) with which the movable component (14) was charged. The correction signals (53, 54, 56) eliminate the influence of translatory and rotatory interference accelerations (y, .THETA.) which act on the base plate (11) of the scale and, without being corrected, would falsify the measuring result (43) or at least unduly extend the measuring time.

Abstract: To detect an intrusion the apparatus projects one or, better, two beams of infrared rays in a direction selected by the user. A lens collects part of the radiation diffused back by the surface on which the beam impinges (whose distance must be in the range covered by the apparatus) and concentrates the collected radiation to form an image, almost pin point, of the "illuminated" surface. The position of said image depends on the distance of the surface impinged on by the beam. A photodetector provided with a slit placed in front is displaced until it detects the radiation forming the image. When the intruder intercepts the beam, the image of the "illuminated" surface, which is now on the intruder, will shift sideways enough to prevent the rays from passing through the slit and therefore from reaching the photodetector. The absence of the photodetector output signal indicates that an intrusion is occuring.

Abstract: To measure the distance to a selected object, the range finder transmits infrared light in a beam having a straight limiting edge on one side. The object reflects light back from the illuminated region and a lens receives part of the light and creates an image of the illuminated region including the straight limiting edge on a plane inclined at an angle to the optical axis of the lens. A detector, including a photoelectric transducer part of which is masked by a mask having a straight edge, is moved along the plane until the edge of the mask and the edge of the image are aligned as closely as possible. The position of the detector when this alignment takes place is indicative of the distance of the object from the range finder.