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696results about "Hollow light guides" patented technology

Thin hollow backlights with beneficial design characteristics

InactiveUS20100156953A1Reduce the total massLosses associated with the light sources are kept to minimal levelsCathode-ray tube indicatorsHollow light guidesBack reflectorLight guide
A backlight unit (10) has a hollow cavity (16) instead of employing a light guide. One or more light sources (24a-c), such as LEDs, are arranged to emit light into the cavity, which is formed by a front (12) and a back reflector (14). The backlight is typically of the edge-lit type. The backlight can have a large area, is thin and consists of fewer components than conventional devices. Its design permits light recycling. The unit emits light of a predefined polarisation and can be arranged to have desired horizontal/vertical viewing angle properties. Light is uniformly distributed within the guide and the light output (20b, 2Od) is substantially collimated. Such backlights occupy a specific region in a parameter space defined by two parameters: first, the ratio of the output emission area to the total source emission area should lie in the range 0.0001 to 0.1; and second, the ratio of the SEP to the height of the cavity (H) should be in the range 3 to 10, where the SEP is an average plan view source separation, a special measure of the average spacing of light sources in the plane of the unit. There is also a discussion on the required number of light sources N, their arrangement near the periphery of the cavity, as well as the shape and size of the output emission area. A required minimum brightness uniformity (VESA) value to be maintained, when a subset of Madjacent sources is switched off (where M is at least 0.1 N or M>2 or both), is also disclosed. The backlight can be used for a display or for general lighting purposes.
Owner:3M INNOVATIVE PROPERTIES CO

Angled illumination tube

An angled illumination tube is capable of reducing a dark spot behind the reflector, while illuminating the tube uniformly over the length of the tube. The tube is used in combination with a light source providing a light beam and comprises an angled transparent tubular conduit having a first end and a second end on opposite longitudinal ends of the conduit. The conduit has a bend between the first and second longitudinal ends, and is used with the first end receiving the light beam from the light source in order to guide the light beam along the length of the conduit. A reflector is disposed within the bend to reflect the light beam from the first end to direct a reflected light beam towards the second end. The reflector defines an incident light axis along which the light beam is guided to the reflector, and a reflected light axis along which the reflected light beam is directed to said second end. The reflector is composed of a plurality of mirrors arranged in a parallel array along a bisector that divides an included angle between the incident and reflected light axes at an angle ( theta ) with respect to the incident light axis. Two adjacent ones of the mirrors are spaced at a fixed distance (d) along the bisector and of uniform length (L) measured within a plane including the incident and reflected light axes. The mirrors are arranged to satisfy the following relation:
Owner:MATSUSHITA ELECTRIC WORKS LTD

Light tube system for distributing sunlight or artificial light singly or in combination

Hybrid lighting systems use light distributor tubes to distribute artificial light and natural sunlight through the same distributor tubes. Devices for gathering uncollimated light from conventional sources (such as electrically energized arcs or filaments housed in evacuated or gas filled glass envelopes) and directing the light into the ends of tubes designed to distribute such light. Devices for gathering and concentrating inherently collimated sunlight to be fed into the same light distributing tubes used by the artificial light. One preferred embodiment comprises a light gathering and concentrating system in the form of a pair of opposed parabolic reflectors, one which is preferably large, e.g. having a diameter of five feet, and the other much smaller, e.g. the size of the much smaller distribution tubes. This light gathering system is connected to the light distribution tubes through a pair 90° elbows which are rotatable in the X and Y axis in order to track the location of the sun in the sky. The two parabolic reflectors are positioned to share a common focal point so that the larger reflector will direct the sunlight through the focal point of the smaller reflector, which will, reflect the light as concentrated, collimated light. A central aperture in the larger reflector passes the concentrated beam on its way to the distribution tubes.
Owner:WALTER A JOHANSON
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