Abstract: An LED light tube for replacement for fluorescent light tubes includes an elongated cylindrical transparent envelope, a base cap at each end of the envelope, and at least one LED device in electrical communication with the base cap. The LED light tube is adapted for use in troffer light fixtures.

Abstract: A light delivery system or device for aiding a medical procedure includes an optical light guide for receiving light from a light source and emitting at least a portion of the light for illuminating a body part of a patient. The light source is capable of generating different frequencies, bandwidths or colors of light for use in different medical lighting applications and the like. Also means are provided for switching the light source between the different frequencies, bandwidths or colors of light on command. The light guide may be in the shape of a rod or panel or may comprise a medical retractor. Alternatively, the light guide may extend along at least a portion of the length of the blade portion of a medical retractor and have a shape substantially corresponding to the shape of the retractor blade portion.

Abstract: The light redirecting films of the present invention have a pattern of individual optical elements that may intersect and/or interlock each other to achieve substantially complete surface coverage of at least one of the surfaces occupied by the optical elements. At least some of the optical elements may have at least one flat surface and at least one curved surface that may intersect each other to a greater extent on the curved surface than on the flat surface to increase the relative percentage of flat surface area to curved surface area of the intersecting optical elements to increase the on axis gain of light passing through the film.

Abstract: Light emitting panel assemblies include a light emitting panel member having at least one light transition area having one or more light sources associated therewith that emit light of multiple colors that are mixed within the light transition area to produce a substantially homogeneous light color distribution within the panel member. A pattern of relatively small individual optical elements on or in at least one of the panel surfaces cause a desired light output distribution to be emitted therefrom.

Abstract: Light emitting panel assemblies include a hollow light emitting panel member having a sheet, film or substrate attached or positioned against one or both sides thereof to produce a desired effect. A pattern of deformities or disruptions may be provided on or in the sheet, film or substrate to control the output ray angle distribution to suit a particular application.

Abstract: Light emitting panel assemblies include a light emitting panel member made of a light extracting material. A pattern of light extracting deformities on or in at least one surface of the panel member adjusts for light output variances of the light output distribution of the panel member due to the light extracting material.

Abstract: Light emitting panel assemblies include one or more light emitting panel members each having at least one pattern of optical deformities that may be varied in size, shape, density, placement, angle, rotation and/or type to obtain at least one light output distribution having a form or shape of at least one of text, graphics, logo or image. At least some of the optical deformities may be shaped or oriented preferentially to cause different colored light propagating through the panel member in different directions to create a multi-colored light output distribution. Also, a plurality of panel members each having a different light output distribution may be placed in overlying relation to one another to produce a composite output distribution when viewed through the panel members or a display overlying the panel members.

Abstract: The methods involve using a tool to cut or form multiple optical element shaped cavities in a surface of a substrate without rotating the tool or substrate during the cutting or forming process. At least some of the cavities are cut or formed to have at least two surfaces that come together to form a ridge and that are quite small relative to the length and width of the substrate. Thereafter the substrate is used to form optical films, components or wave guides having multiple optical elements on at least one surface corresponding to the cavities in the substrate.

Abstract: Optical assemblies include a light emitter having at least one layer of a transparent film, sheet or plate through which light emitted by the light emitter passes. A pattern of deformities of well defined shape on or in at least one side of the film, sheet or plate control an output ray angle distribution of light emitted by the assemblies to suit a particular application. The film, sheet or plate causes a change in color or color correction in the light emitted by the assemblies.

Abstract: Differential measurement of a transformer magnetizing current and a delta-modulation technique is used to provide compensation for dc saturation of the transformer core, with faster response times, low losses, and with immunity to dc drift in the measuring electronics. During the half-cycle in which the output voltage transitions from its positive maximum to its negative maximum, the positive peak value of the magnetizing current is determined, and during the half-cycle in which the output voltage transitions from its negative maximum to its positive maximum, the negative peak value of the magnetizing current is determined. The positive peak magnetizing current value is compared to the similar value from the previous cycle, and the onset of core saturation in the positive direction is then determined. The negative peak magnetizing current value is compared to the similar value from the previous cycle, and the onset of core saturation in the negative direction is then determined.

Abstract: An LED light tube for replacement for fluorescent light tubes includes an elongated cylindrical transparent envelope, a base cap at each end of the envelope, and at least one LED device in electrical communication with the base cap. The LED light tube is adapted for use in troffer light fixtures.

Abstract: Notching in a switch-mode converter is compensated for to restore a sinusoidal output voltage waveform to the output of the converter, regardless of the load current level, power level, or power factor (both distortion and displacement power factor). Waveform smoothing for a waveform in a switch-mode converter having a DC bus voltage and an output filter inductance comprises determining a ripple current in the converter; determining a time-to-zero; determining a turn-on time; determining the lesser of the time-to-zero and the turn-on time; determining a duty cycle modification based on the lesser of the time-to-zero and the turn-on time; and applying the duty cycle modification to the waveform.