Abstract: The invention relates to measurements of light, where light variations superimposed on a background amount of light, which is changing relatively slowly, are measured. To give the light sensitive element (3,3') used a stable operational point a light emitting element (5,5') is used for injecting extra light into the light sensitive element (3,3'). Thus, the amount of light injected by this light emitting element (5,5') is chosen in such a way that the sum of the ambient light and the injected light is substantially constant. To this amount of light are added the light variations, e.g. caused by a second light emitting element (9,9'). This process and device can be used in a device for measuring the eye movements of a person.

Abstract: In a device for measuring the movements of a person's eye there are one or more sets of cooperating light detecting elements and light emitting elements intended primarily for measuring in chosen selected directions. Each set could consist of two light detecting elements located at a distance on each side of the eye and symmetrically with respect to the eye and in a symmetry plane of the eye containing the direction chosen. The associated light emitting elements are located, also symmetrically, in a plane substantially orthogonal to the plane with the light detecting elements. When many sets of cooperating light emitting and detecting elements of this kind are combined into a symmetrical or semisymmetrical arrangement, this permits selecting, for an eye movement in a given direction, the most suitable set for detecting the eye movement in this direction. Only one set of light emitting elements, assigned to the axis of measurement, is active at a time.

Abstract: Device for measuring eye movements. At least two radiation sources are located in front of the eyes and at least two radiation detectors are adapted to detect the radiation reflected from the eye, whereby the detectors are located in connection with the radiation sources. In accordance with the invention the radiation sources (3,4) and the detectors (5,6) are disposed in pairs so that one pair is arranged on each side of at least one symmetry plane through the centered eye. The at least two pairs are disposed on a diaphragm (1) which is located at a certain distance from the eye (8) and which is provided with an aperture (2) straight opposite to the eye having a certain form and size thereby to permit the eye to look through the aperture within a certain space angle. A shielding member (7) is disposed aroused the diaphragm and the eye in order to prevent disturbing light from impinging into the eye beyond the light falling through the aperture.

Abstract: An electrically powered wheel-chair for indoor and outdoor use comprising a pair of rear main wheels, which are non-pivotably connected with the frame-work of the chair, at least one of said wheels being driven by an electric motor. A steering wheel being rotatably connected with the frame-work of the wheel-chair and positioned in front of the main wheels, said steering wheel being asymmetrically located on one side of a longitudinal axis through the middle of the chair. A support wheel being positioned on the other side of said longitudinal axis relative to the steering wheel at such a level above a flat and horizontal ground surface that it will not touch this surface when the steering wheel directed straight ahead. The diameter of the support wheel is less than that of the steering wheel and the distance from the fore-most point of the steering wheel to a transverse axis through the centers of the main wheels is greater than the corresponding distance for the support wheel.

Abstract: A hand operated wheel-chair with a pair of main wheels rigidly connected with the frame-work of the chair, at least one of which is either motor or hand operated and at least one castor wheel being pivotally connected with the frame-work of the chair and at least one support wheel being rigidly connected with the frame-work. At least one castor wheel and support wheel are positioned on each side of a line extending between the support points of the main wheels and at a level above the ground surface to permit either the castor or the support wheels to be in contact with the ground surface depending on whether the vertical through the center of gravity is located on one or the other side of said line between the support points of the main wheels.