Optical: systems and elements – Projection screen – Embedded particles
Reexamination Certificate
2008-03-04
2008-03-04
Mahoney, Christopher (Department: 2862)
Optical: systems and elements
Projection screen
Embedded particles
C359S460000
Reexamination Certificate
active
10566244
ABSTRACT:
The present invention relates to a rear-projection screen encompassing at least one light-scattering polymethyl methacrylate layer, which comprises a polymethyl methacrylate matrix and spherical scattering particles (A) and spherical particles (B) with a different median particle size V50, where the spherical scattering particles (A) have a median size V50in the range from 0.1 to 40 μm, the difference between the refractive index of the spherical scattering particles (A) and that of the polymethyl methacrylate matrix being in the range from 0.02 to 0.2, where the spherical particles (B) have a median size V50in the range from 10 to 150 μm, the difference between the refractive index of the spherical particles (B) and that of the polymethyl methacrylate matrix being in the range from 0 to 0.2, and where the total concentration of the spherical scattering particles (A) and particles (B) is in the range from 1 to 60% by weight, based on the weight of the light-scattering polymethyl methacrylate layer, where the concentration of the spherical scattering particles (A) cPA, the thickness of the light-scattering polymethyl methacrylate layer dSand the size of the spherical scattering particles (A) DPAis selected in such a way that the ratio cPA*dS/DPA3is in the range from 0.001 to 0.015% by weight*mm/μm3, the concentration of the spherical particles (B) cPB, the thickness of the light-scattering polymethyl methacrylate layer dSand the size of the spherical particles (B) DPBis selected in such a way that the ratio cPB*dS/DPB3is in the range from 0.000005 to 0.002% by weight*mm/μm3and the ratio of the square of average surface roughness of the polymethyl methacrylate layer RZto the third power of the size of the spherical particles (B) RZ2/DPB3is in the range from 0.0002 to 0.1300 μm−1.
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Dickhaut-Bayer Guenther
Groothues Herbert
Krohmer Christoph
Parusel Markus
Schmidt Jann
Mahoney Christopher
Roehm GmbH & Co. KG
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