Abstract: A display system, method and backlight unit for use with a display. The backlight unit includes a first light source and a second light source, wherein the first light source and the second light source are controllable independently of each other. The sum of light produced by the light sources illuminates the display to achieve illumination brightness capability of a higher intensity capable single light source. Changes in spectral characteristics and/or brightness characteristics due to aging or the like may be compensated. The first light source may provide a base line illumination level for the display and the second light source may be modulated to dynamically increase contrast and/or contrast ratio characteristics of the image being shown on the display to a viewer.

Abstract: A variable retarder is inserted in one or more light channels of a kernel. The variable retarder is a nematic liquid crystal layer that is energized by an electric field and, for example, the voltage or frequency of the electric field dictates an amount of retardation effected by the variable retarder. The variable retarder either increases or decreases an optical path in which it is inserted relative to a reference. The amount of increase or decrease is utilized to place light paths in the kernel within acceptable tolerances. The acceptable tolerances are, for example, a tolerance of difference-light paths expected by a projection lens of device using the kernel for light modulation. In one embodiment, the variable retarder includes a polymer that can be used to fix a retardation value of the variable waveplate.

Abstract: A transmissive LCD is placed in optical series with pixels of an image. The transmissive LCD is set to full transmissivity when bright pixels of the image pass through the transmissive LCD. Transmissivity is decreased where pixels darker than a darkening threshold pass through the transmissive LCD. A darkening curve representative of an amount of darkening performed by the transmissive LCD provides an amount of darkening to be performed on each pixel. Preferably, the darkening curve gradually darkens pixels more as the pixels themselves are darker. The darkening curve may be implemented as a formula or a look-up table in software or drive electronics that energize the transmissive LCD. Both the darkening threshold and the darkening curve may be user selectable.

Abstract: A variable retarder is inserted in a polarized light beam. The retardance of the variable retarder is increased when the light beam increases in brightness and is decreased when the light beam decreases in brightness. The amount of increase and/or decrease in retardance is calculated to stabilize the brightness of the light beam. The variable retarder may be used in conjunction with an auto-iris and share a same brightness detector.

Abstract: Ultra Violet (UV) light produced by a light source is converted to visible light and utilized in a visible light output of the light source. The light source is, for example, a light source in an illuminator of a projection device. UV light that is typically filtered out of the illuminator is converted by a UV absorbing visible light radiating phosphor. The UV light is directed to the phosphor by, for example, reflecting the UV light out of a light path, concentrating the UV light via a concave reflector, and directing the UV light to the phosphor. The re-radiated visible light is then injected back into the light path of the light source. In one embodiment, the re-radiated visible light is injected into a “shadow” of the light path.

Abstract: A hollow sphere with a scattering (e.g., white diffusive) interior surface directs light input from at least one input light source to an exit. The exit has a reflective polarizer that passes light of a selected polarization to an output. Light of other polarization(s) is reflected back into the sphere where it becomes unpolarized because of reflections and may eventually be returned to the exit at the selected polarization. The illuminator is well suited as a light source for light management systems of various configurations.

Abstract: Images to be displayed are produced for left-eye viewing and right-eye viewing in synchronization with a polarization device that alternately changes polarization of the viewed images. In one embodiment, a control mechanism synchronizes modulation performed by microdisplays in a reflective Liquid Crystal On Silicon (LCOS) kernel with an electronically controlled shutter that alternately converts light output from the LCOS kernel between S and P polarizations. Prior to reaching the shutter (or other polarization switching device) a wavelength specific retarder is utilized so that the polarizations of various light channels are homogenous. The kernel installed in, for example, a 3-D enabled monitor, 3-D gaming device, or a 3-D enabled High Definition (HD) LCOS Rear projection television (RPTV).

Abstract: Frames are used to hold and/or position components in precise positions in a prism assembly. The frames may be constructed using any of side caps, air gaps, recesses, and hold either a single or multiple planar components. The frames are, for example, immersed in liquid filled channels between adjacent faces of beamsplitters in the prism assembly. The planar components themselves may include waveplates, optical flats, spacer glasses, retarders, Color Selects, substrates, or any other components of the optical device. The planar components may themselves include multiple layers (e.g., polarizers, dichroics, etc). In one embodiment, a polarizer and an air gap are provided. The invention increases precision, lowers cost, and improves quality (e.g., contrast ratio) of any number of devices, but is particularly applicable to Liquid Crystal on Silicon (LCOS) and other microdisplay based projection systems such as High Definition (HD) Rear Projection Televisions (RPTVs).

Abstract: An absorptive layer is added to an image display system. The absorptive layer is selected to compensate for tint in a black state of a displayed image. In a Liquid Crystal On Silicon (LCOS) based light engine, blue wavelengths may cause a predominate tint in black portions of an image (or an entirely black image is tinted blue), and the absorptive layer is calculated to absorb an amount of blue equivalent to the tint. The absorptive layer is, for example, an unbalanced magenta dichroic, or a yellow filter. The yellow filter may be placed at any point in the light chain, including input/output of a kernel, input/output of a projection lens, or portions of a light engine or display screen. An unbalanced magenta may be constructed by adding a yellow filter to an existing magenta dichroic in the kernel design.

Abstract: Kernels are designed in different configurations based on design properties of an enclosure or other requirements. A prism assembly having various types of filters, waveplates, beam splitters (e.g., path length matched beam splitters) and/or other optical components are provided to selectively direct light beams to each of red, green, and blue microdisplays that manipulate the light and then combine the manipulated lights into an output image. The prism assembly includes an input face, an output face, and other faces on which the microdisplays are attached in a number of different configurations. Requirements and exact placement of optical components varies depending on which microdisplay is attached to which face. The components of the prism assembly may be arranged in path length matched positions.

Abstract: A Liquid Crystal on Silicon (LCOS kernel for a light engine is configured in a kernel having light paths in three dimensions (3D kernel). The 3D kernel allows for designs that do not require Wavelength Dependent Waveplates (WDWs) (or Wavelength Specific Retarders) for managing light polarizations within the 3D kernel. In one embodiment, the 3D kernel includes a Polarizing Beam Splitter (PBS) that is positioned to direct lightpaths within the 3D kernel in the 3rd dimension (e.g., light path planes perpendicular to planes of input light provided to the 3D kernel). The 3rd dimension is, for example, an output light path perpendicular to an input light plane. The 3D kernel allows for designs that incorporate reflective LCOS microdisplays and management of light paths without WDWs. The kernel is suitable for use in High Definition (HD) LCOS Rear Projection Televisions (RPTVs) and other projector applications.

Abstract: A variable retarder and linear polarizer are placed in series in a polarized light path. A transmission axis of the linear polarizer is parallel to an axis of a polarization of the polarized light. An amount of retardation dialed into the variable retarder causes an amount of the light to have a component with an amount of off axis polarization. The off-axis components do not pass the linear polarizer, causing a reduction in the brightness of the polarized light. The combined variable retarder and linear polarizer operate as a light shutter that may be utilized, for example, to increase contrast ratio and bit depth regardless of light level in a video projection system (e.g., LCoS light engines).

Abstract: A hollow sphere with a scattering (e.g., white diffusive) interior surface directs light input from at least one input light source to an exit. In one embodiment, an internal hot mirror and phosphor are positioned to intercept the input light on which visible light is reflected and ultraviolet light is directed to the phosphor for conversion to visible light. The exit has a reflective polarizer that passes light of a selected polarization to an output. Light of other polarization(s) is reflected back into the sphere where it becomes unpolarized because of reflections and may eventually be returned to the exit at the selected polarization.

Abstract: An optical element (e.g., wavelength dependent retarder (ColorSelect), dichroic, and/or optical shutter) is disposed in a projection lens at a point in the projection lens where the area of the light beam being projected is minimized. The optical element(s) is utilized for polarization control and/or brightness leveling or other optical effects. The optical element(s) matches the size and shape of a light ray bundle passing through the minimized point in the projection lens. The minimized size and shape of the optical element(s) reduces the cost of the element(s). The minimized location is for example, between a first and second set of lens in the projection lens. The location also reduces variations in the post optical element light train caused by impacting lens element surfaces. The projection lens is utilized, for example, in a Liquid Crystal on Silicon (LCoS) based High Definition (HD) Rear Projection Television (RPTV).

Abstract: A dichroic is positioned to separate color beams of polarized input light. The color beams are directed to microdisplays that contain correspondingly colored content in a kernel of a Light Management System (LMS). Adjustment of a voltage amplitude of the microdisplays is set to produce a maximum black state of the LMS. In one embodiment, a passive nematic liquid crystal device is utilized as a quarter waveplate. A thickness of a liquid crystal layer (d) is matched to a birefringence (?n) of the nematic such that retardation d?n =¼?.

Abstract: An absorptive layer is added to an image system. The absorptive layer is selected to compensate for tint in a black state of the image. The absorptive layer is inserted in an image light stream (or light chain) and then tilted or rotated to precisely tune the band [bandwidth] of the absorptive layer to produce a desired neutral dark state. In a Liquid Crystal On Silicon (LCOS) based light engine, blue wavelengths may cause a predominate tint in black portions of an image (or an entirely black image is tinted blue), and the absorptive layer is calculated to absorb an amount of blue equivalent to the tint. The absorptive layer is, for example, a yellow notch filter. The absorptive layer may also be placed in camera image chain.

Abstract: Ultra Violet (UV) light produced by a light source is converted to visible light and utilized in a visible light output of the light source. The light source is, for example, a light source in an illuminator of a projection device. UV light that is typically filtered out of the illuminator is converted by a UV absorbing visible light radiating phosphor. The UV light is directed to the phosphor by, for example, reflecting the UV light out of a light path, concentrating the UV light via a concave reflector, and directing the UV light to the phosphor. The re-radiated visible light is then injected back into the light path of the light source. In one embodiment, the re-radiated visible light is injected into a “shadow” of the light path.

Abstract: A transmissive LCD is placed in optical series with pixels of an image. The transmissive LCD is set to full transmissivity when bright pixels of the image pass through the transmissive LCD. Transmissivity is decreased where pixels darker than a darkening threshold pass through the transmissive LCD. A darkening curve representative of an amount of darkening performed by the transmissive LCD provides an amount of darkening to be performed on each pixel. Preferably, the darkening curve gradually darkens pixels more as the pixels themselves are darker. The darkening curve may be implemented as a formula or a look-up table in software or drive electronics that energize the transmissive LCD. Both the darkening threshold and the darkening curve may be user selectable.

Abstract: Frames are used to hold and/or position components in precise positions in a prism assembly. The frames may be constructed using any of side caps, air gaps, recesses, and hold either a single or multiple planar components. The frames are, for example, immersed in liquid filled channels between adjacent faces of beamsplitters in the prism assembly. The planar components themselves may include waveplates, optical flats, spacer glasses, retarders, Color Selects, substrates, or any other components of the optical device. The planar components may themselves include multiple layers (e.g., polarizers, dichroics, etc). In one embodiment, a polarizer and an air gap are provided. The invention increases precision, lowers cost, and improves quality (e.g., contrast ratio) of any number of devices, but is particularly applicable to Liquid Crystal on Silicon (LCOS) and other microdisplay based projection systems such as High Definition (HD) Rear Projection Televisions (RPTVs).

Abstract: Light is managed through the use of a light shutter. The light shutter is, for example, a variable retarder in series with a reflective linear polarizer in a polarized light beam. A comet tail effect caused by transition latencies of pixels in microdisplays of a light engine is effectively removed by closing the shutter during pixel transition times. In addition to suppressing the comet tail effect, the light shutter may also be used to level light intensity (or brightness) of an input light source that supplies a light engine, and may be used to adjust the input light intensity to more effectively utilize a full modulation range of modulating devices in the light engine.