3m Innovative Properties Company

David J W Aastuen

Charles L Bruzzone

Jiaying Ma

Stephen K Eckhardt

Craig R Schardt

Stephen J Willett

Michael F Weber

Timothy J Nevitt

Zhisheng Yun

Gilles J Benoit

Timothy L Wong

Gary Timothy Boyd

John D Le

Jo Anne Etter

Robert M Jennings

Arthur L Kotz

William T Fay

Roger J Strharsky

John Allen Wheatley

Takashi Fujita

Kenneth A Epstein

Adam D Haag

Michael L Steiner

David T Yust

Susan L Kent

Byung-Soo Ko

Lin Zhao

Michael P Keyes

Abolghassem B Mahmoodi

A display includes a plurality of blue, green, and red light emitting elements having respective blue, green, and red emission spectra including respective blue, green, and red emission peaks at respective blue, green, and red peak wavelengths with respective blue, green, and red full width at half maxima (FWHMs). The display includes a display panel and an optically collimating film. For a substantially collimated incident light and for each of mutually orthogonal polarization states, an optical transmittance of the optically collimating film includes substantially distinct blue, green, and red transmission bands having respective blue, green, and red FWHMs that overlap at least 30% of the respective blue, green, and red FWHMs at a first incident angle of less than about 10 degrees and overlap less than 15% of the respective blue, green, and red FWHMs at a second incident angle of greater than about 30 degrees.

Display and display system

An optical film and a polarizing beam splitter (PBS) including the optical film is described. The optical film includes a first optical stack disposed on, and spaced apart by one or more spacer layers from, a second optical stack. When the optical film is disposed between, and adhered to, hypotenuses of first and second prisms to form a PBS and a cone of light is incident on the PBS making an incident angle of about 40 to 50 degrees with the optical film, the PBS has: an average optical reflectance Rs greater than about 95% for a first polarization state; an average optical transmittance Ts less than about 0.012% for the first polarization state; an average optical transmittance Tp less than about 98.5% for a second polarization state; and an average optical reflectance Rp less than about 0.25% for the second polarization state.

Optical film and polarizing beam splitter

An optical system for displaying an image to a viewer includes a pixelated display including a plurality of pixels emitting unpolarized image light; a partial reflector having an average optical reflectance of at least 30% in a predetermined wavelength range; a first retarder layer disposed between the pixelated display and the partial reflector; a second retarder layer disposed between the first retarder layer and the partial reflector; and a reflective polarizer disposed between the first and second retarder layers. The reflective polarizer is adapted to increase a brightness of a pixelated image emitted by the pixelated display and displayed to the viewer by recycling at least a portion of unpolarized image light emitted by the pixels; and receive an image ray reflected by the partial reflector and reflect the received image ray toward the viewer.

Optical system

An optical film includes a plurality of polymeric layers shaped along orthogonal first and second directions. A first curve being an intersection of the optical film with a first plane orthogonal to the second direction and to a reference plane has a best-fit first circular arc subtending a first angle at a center of curvature of the first circular arc of greater than 180 degrees where the optical film has a maximum projected area in the reference plane. A second curve being an intersection of the optical film with a second plane orthogonal to the first direction and to the reference plane has a best-fit second circular arc subtending a second angle at a center of curvature of the second circular arc of at least 30 degrees. Reflectance and transmittance of the optical film are described.

Shaped optical films and methods of shaping optical films

Optical films having a curved shaped and methods of shaping optical films are described. A method of shaping an optical film includes the steps of disposing the optical film adjacent first and second rollers spaced apart along a first direction, securing opposing first and second ends of the optical film, providing a curved mold surface, and shaping the optical film by contacting the optical film with the curved mold surface while stretching the optical film along the first direction and keeping a threshold distance between closest points on the optical film contacting the first roller and contacting the curved mold surface less than the width of the optical film to reduce buckling of the optical film.

Projection subsystems are described. More, particularly, projection subsystems that include a light source and a polarizing beam splitter are described. The polarizing beam splitters of the presently described projection subsystems are capable of avoiding performance degradation even after exposure to large doses of incident light.

Projection subsystem

In one embodiment, the invention provides backlight comprising a front reflector () and a back reflector () disposed to form a hollow light cavity () with a first light source () proximate one end of the front reflector () and having a tilt angle () of from 5&#xb0; to 90&#xb0;, and a first asymmetric light collimator () extending between at least the first light source () and the back reflector () for directing light from the first light source () into the hollow light cavity ().

Hollow backlight with tilted light source

An optical system is provided. The optical system comprises a first polarizing beamsplitter (PBS), a first reflecting image-forming device, and a first quarter-wave retarding element. An optical system is also provided that comprises an image-forming device, a reflective polarizing layer, at least a first birefringent element disposed on an optical path between the image-forming device and the polarizing layer, and a quarter-wave retarding element. Further provided is an optical system comprising a color combiner unit, at least two polarizing beamsplitters (PBSs), and a first quarter-wave retarding element. The present application also provides methods of compensating for birefringence in an image projection system.

Stress birefringence compensation in polarizing beamsplitters and systems using same

An optical imaging system including an illumination system, a Cartesian PBS, and a prism assembly. The illumination system provides a beam of light, the illumination system having an &#x192;/# less than or equal to 2.5. The Cartesian polarizing beam splitter has a first tilt axis, oriented to receive the beam of light. A first polarized beam of light having one polarization direction is folded by the Cartesian polarizing beam splitter and a second polarized beam of light having a second polarization direction is transmitted by the Cartesian polarizing beam splitter. The Cartesian polarizing beam splitter nominally polarizes the beam of light with respect to the Cartesian beam splitter to yield the first polarized beam in the first polarization direction. The color separation and recombination prism is optically aligned to receive the first polarized beam. The prism has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces. The second tilt axis may be oriented perpendicularly to the first tilt axis of the Cartesian polarizing beam splitter so that the polarized beam is nominally polarization rotated into the second polarization direction with respect to the color separating surfaces and a respective beam of colored light exits through each of the exit surfaces. Each imager is placed at one of the exit surface of the color separating and recombining prism to receive one of the respective beams of colored light, wherein each imager can separately modulate the polarization state of the beam of colored light.

Reflective LCD projection system using wide-angle cartesian polarizing beam splitter and color separation and recombination prisms

Single imager projection systems suffer from low light throughput, compared to three imager systems, because only one color band is illuminated at any one time. As a result, there is a need to increase the operating efficiency of the single imager projection system. The invention is directed to the incorporation of a high extinction ratio pre-polarizer, such as a compensated, multi-layer polarizer, in a single or dual imager projection system. This permits illumination with low f-number illumination light, and thus increases the efficiency of the projection system. The pre-polarizer may be incorporated within a polarization recovery unit to further enhance system efficiency.

Highly efficient single panel and two panel projection engines

A projection system includes an image-forming device and a polarizing beamsplitter. Illumination light illuminates the image-forming device via the first polarizing beamsplitter. A retardation element is disposed between the image-forming device and the polarizing beamsplitter. A bias controller applies a bias to pixels of the image-forming device in the dark state so as to substantially maximize contrast in image light reflected from image-forming device. In some arrangements, the volume between the polarizing beamsplitter and the image-forming device is sealed, with the retarding element being disposed within the sealed volume and being attached to either the polarizing beamsplitter or the image-forming device.

Birefringence-compensated liquid crystal display and projection system using same

Some projection systems use a polarization beamsplitter (PBS) for coupling light to and from an image-forming device. The PBS is typically formed with a reflective polarizing layer disposed between glass covers. Stress birefringence in the glass cover lying between the reflective polarizing layer and the image-forming device can reduce the image contrast of the projection system. A quarter-wave retarding element positioned between the glass cover and the image-forming device is used to compensate for the birefringence, at least in part. This permits the PBS to use glass covers formed of a glass material having a higher stress optic coefficient than before, while still maintaining high image contrast.

Growing community of inventors

Shoreview, MN, United States of America

David J W Aastuen