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US 2003/0151834 A1Published application
Prism for high contrast projection
AssigneeTexas Instruments Incorporated
InventorSteven M. Penn
Life of this patent
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AssigneeTexas Instruments Incorporated
InventorSteven M. Penn
Estimating the term…
Prism elements having TIR surfaces placed in close proximity to the active area of a SLM device 302 to separate unwanted off-state 324 and/or flat-state 326 light from the projection ON-light bundle 322. The TIR critical angle of these prisms is selected to affect either the off-state light or additionally, any portion of flat-state light reflected from the SLM. These TIR surfaces are placed to immediately reflect the unwanted light as it comes off the SLM, thereby preventing the contamination of light along the projection path, which tends to degrade the system contrast. To further improve the optical performance of the system, these TIR prisms can be attached directly to the SLM package 300, completely eliminating the package window. Also, these TIR prism can be coupled to DMDs having asymmetric mirrors, which tilt through a larger angle for the ON-light to provide high etendue and lumen output, but through near-zero degrees for the OFF-light, thereby improving the separation of any unwanted light from the off/flat states.
A low-cost prism assembly for use with single-chip spatial light modulator projection systems, comprising:
The prism assembly of claim 22, wherein said projection illumination passes through a single prism element and one SLM package window.
The prism assembly of claim 22, wherein the SLM window is eliminated, said SLM package window seal being attached directly to said third side of said third prism, thereby shortening the optical path, reducing the number of optical elements, reducing the amount of system contamination, reducing the size and cost of said assembly, and further increasing the contrast of said projection system.
The prism assembly of claim 24, wherein said SLM is a DMD.
The prism assembly of claim 25, wherein said DMD has symmetric micromirrors, which tilt the same number of degrees in both the positive and negative direction about a diagonal axis.
The prism assembly of claim 25, wherein said DMD has asymmetric micromirrors, which tilt x degrees in the positive ON light direction and less than x degrees in the negative OFF light direction, further decreasing the scattering of unwanted light into said projection path, thereby further improving the contrast of said projection system.
A high contrast prism assembly for use with projection systems having two or more SLMs, comprising:
The prism assembly of claim 28, wherein said respective SLM package windows are eliminated, said SLM package window seal being attached directly to said prism surfaces, thereby shortening the respective optical paths, reducing the number of optical elements, reducing the amount of system contamination, reducing the size and cost of said assembly, and further increasing the contrast of said projection system.
The prism assembly of claim 29, wherein said SLM is a DMD.
The prism assembly of claim 30, wherein said DMD has symmetric micromirrors, which tilt the same number of degrees in both the positive and negative direction about a diagonal axis.
The projection display system of claim 30, wherein said DMD has asymmetric micromirrors, which tilt x degrees in the positive ON light direction and less than x degrees in the negative OFF light direction, further decreasing the scattering of unwanted light into said projection path, thereby further improving the contrast of said projection system.
Dependencies are inferred from the claim text.