Optical: systems and elements – Glare or unwanted light reduction – Directional or angular discrimination
Reexamination Certificate
2000-11-15
2002-06-04
Dang, Hung Xuan (Department: 2873)
Optical: systems and elements
Glare or unwanted light reduction
Directional or angular discrimination
C359S614000, C359S601000, C428S167000, C428S172000
Reexamination Certificate
active
06398370
ABSTRACT:
The present invention pertains to light control devices that allow higher transmission over one range of viewing angles and lower transmission over another range of viewing angles.
BACKGROUND
Light control films, or light collimating films, are known in the art and have been made in various ways. One type of light control film includes alternating plastic layers of relatively high and relatively low optical density. The high optical density layers provide light-collimating louver elements. Louvered plastic light control films have been disclosed that have louvers having central regions withRelatively high coefficients of extinction and outer regions with lower coefficients of extinction. The presence of the lower coefficient regions can reduce the formation of ghost images due to glancing angle reflections off the louver elements. Another type of light control film includes a film or plate that has grooves or channels that are filled or coated with a light absorbing material.
SUMMARY OF THE INVENTION
The present inventors have discovered a new light control device that is relatively easy to manufacture, can be made having high aspect ratio absorbing elements, can be made to reduce ghost image formation, and that is adaptable to many different absorbing element shapes, sizes, and spacings, depending on the desired effect.
In one embodiment, the present invention provides a light control device that includes a first light transmissive film that has a first plurality of light absorbing regions extending into a surface thereof and a second light transmissive film disposed adjacent to the first light transmissive film that includes a second plurality of light absorbing regions extending into a surface thereof. The first plurality of light absorbing regions and the second plurality of light absorbing regions are relatively positioned to allow a viewer to view an image through the light control device at some viewing angles and to block viewing of the image through the light control device at other viewing angles.
In another embodiment, the present invention provides a process for making a light control device. The process includes the steps of forming a first light transmissive film that has a first plurality of indentations extending into a surface thereof, forming a second light transmissive film that has a second plurality of indentations extending into a surface thereof, rendering the first and second plurality of indentations light absorbing, and adjacently disposing the first and second light transmissive films. The light control device functions in a manner that when the light control device is positioned between an image and a viewer, the light control device is capable of allowing the viewer to view the image through the light control device within a range of viewing angles and to block viewing of the image through the light control device outside the range of viewing angles.
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
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Chiu Raymond C.
Gaides Gary E.
Humpal Paul E.
Sano Koichi
3M Innovative Properties Company
Buckingham Stephen W.
Dang Hung Xuan
Tra Tuyen
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