Abstract: This invention provides a liquid crystal achromatic polarization rotator switch, and an achromatic shutter using the rotator switch. The rotator switch requires input light of a fixed orientation and switches between rotating the polarization by zero degrees and by a fixed angle, .beta.. The achromatic shutter uses an achromatic 90-degree rotator switch positioned between a pair of polarizers. A first embodiment of the rotator switch comprises one planar-aligned rotatable smectic liquid crystal half-wave retarder in series with one passive half-wave retarder. The smectic liquid crystal cell has fixed retardance and is driven between two orientations for off- and on-states. A second embodiment of the rotator switch utilizes two variable birefringence liquid crystal cells. The variable birefringence cells having fixed orientation and variable retardance. In the off-state both retarders have zero retardance and in the on-state they have half-wave retardance.

Abstract: This invention provides a liquid crystal achromatic polarization rotator switch, and an achromatic shutter using the rotator switch. The rotator switch requires input light of a fixed orientation and switches between rotating the polarization by zero degrees and by a fixed angle, .beta.. The achromatic shutter uses an achromatic 90-degree rotator switch positioned between a pair of polarizers. A first embodiment of the rotator switch comprises one planar-aligned rotatable smectic liquid crystal half-wave retarder in series with one passive half-wave retarder. The smectic liquid crystal cell has fixed retardance and is driven between two orientations for off- and on-states. A second embodiment of the rotator switch utilizes two variable birefringence liquid crystal cells. The variable birefringence cells having fixed orientation and variable retardance. In the off-state both retarders have zero retardance and in the on-state they have half-wave retardance.

Abstract: The invention concerns a control system for adjusting the rear view mirror of a vehicle in response to the position of the steering gear. This object is achieved in that the apparatus the controlling parts, viz. a magnet and a reed contact are simple and inexpensive elements which can be so positioned without difficulty as to sense the movements of the steering gear, and their function is quite unaffected by the rough conditions by way of road dirt, water and oil to which they may be subjected when placed below the front end of a vehicle.

Abstract: A control system for automatic adjustment of the rearview mirrors (6) of a vehicle (1) and of the type where the horizontal angular position of the mirror, via airborne signals (8) from transmitter and receiver means (7, 14), is changed by means of a drive unit (5) in response to the mutual horizontal angular position between coupled vehicle parts (2,3), and where transmitter and receiver are positioned on their respective vehicle parts.

Abstract: Tartar formation on teeth is prevented with compositions of a sodium salt ethylenediaminetetraacetic acid having a pH between about 5.5 and 9.0 in a carrier which permits application to the teeth. Aqueous solution may be used for this purpose as well as toothpaste compositions.

Abstract: In order to obtain a reliable position determination in a hydraulic cylinder optionally exposed to hard frost, it is suggested to mount a magnetically sensitive component in the form of a Hall-effect transducer in a bore in the cylinder wall and placed between a permanent annular magnet (17) and a magnetically conducting sheet (14). In the middle of the bore a magnetically conducting post (16) is placed and towards the inner side of the cylinder the bore is sealed by a non-magnetic material (19) e.g. brass. The Hall-effect transducer (15) forms thus part of a closed magnetic circuit comprising the permanent magnet (17), the magnetically conducting post (16), the magnetically conducting disc (14) and the hydraulic cylinder wall surrounding the bore. When the piston in the hydraulic cylinder opposes the sensor, a second closed magnetically conducting circuit is formed comprising the permanent magnet, the magnetically conducting post, the piston, and the steel wall of the cylinder.

Abstract: A cylindrical or conical bobbin (1) resiliently compressible both in axial and in radial direction and supporting textile strands to be subjected to a heat and/or wet treatment has an outer grating (3), the outer side of which forms the curved surface of the bobbin (1), the curved surface serving as a supporting surface for the strands. The bobbin (1) includes means (2, 2', 2", 3, 4, 5) which retain the grating (3) when the bobbin (1) is not compressed more than a predetermined length in the axial direction in such a manner that the outer surface is positioned in a radial outer position, and which release the grating (3) when the bobbin (1) is axially compressed more than a predetermined length in such a manner that the outer surface is inwardly displaceable into a radial inner position, and which prevent an additional inward displacement of the outer surface.