Microstructured rear projection screen

• US 6,636,355 B2
• Filed: 12/27/2000
• Issued: 10/21/2003
• Est. Priority Date: 12/27/2000
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Rhyner, Steven J., Cullen, Peter F., Pokorny, Richard J., Nelson, John C., Moshrefzadeh, Robert S., Thomas, Patrick A.
• Primary Examiner(s): Adams, Russell
• Assistant Examiner(s): Cruz, Magda
• Application Number:
  US09/748,977
• Publication Number:
  US 20020080484A1
• Time in Patent Office: 1,028 Days
• Field of Search: 359/460, 359/443, 359/453, 359/454, 359/455, 359/456, 359/459
• US Class Current: 359/460
• CPC Class Codes: G03B 21/625 Lenticular translucent screens

Abstract

Disclosed is a rear projection screen that includes a plurality of tapered waveguides and a light absorbing layer disposed over the tops of the waveguides, but that does not completely fill the spaces between the waveguides, thereby forming an interstitial low index region under the light absorbing layer and between the waveguides. The low index interstitial region can include air or a material that has a lower index of refraction than the waveguide material. This rear projection screen construction can give rise to increased efficiency and higher contrast, as well as allow for more design freedom in constructing screens that have desired characteristics such as viewing angle, viewing asymmetry, and the like. Also disclosed are methods for making the described microstructured rear projection screen.

Claims

1. A method for making a rear projection screen comprising the steps of:

disposing a plurality of waveguides on a transmissive substrate, the waveguides being tapered from a wider back portion near the substrate to a narrower front portion away from the substrate; and

extruding a light absorptive material over the waveguides to thereby form a light absorptive layer disposed between adjacent waveguides so that the light absorptive layer contacts the waveguides at or near the front portions of the waveguides, thereby defining interstitial regions between adjacent waveguides and the light absorptive layer, the interstitial regions having a lower refractive index than the waveguides.

2. The method of claim 1, wherein extruding the light absorptive material over the waveguides causes a local deformation at the front portion of the waveguides, thereby forming lenslets.

3. The method of claim 1, wherein extruding a light absorptive material comprises coextruding a light absorptive material and a substantially clear material onto the waveguides.

4. The method of claim 3, wherein extruding the light absorptive material over the waveguides causes a local deformation at the front portion of the waveguides, thereby forming lenslets.

5. A method for making a rear projection screen comprising the steps of:

disposing a plurality of waveguides on a transmissive substrate, the waveguides being tapered from a wider back portion near the substrate to a narrower front portion away from the substrate; and

laminating a layered structure on the front portions of the waveguides, the layered structure comprising a light absorptive layer and a second layer, the light absorptive layer positioned between the waveguides and the second layer during lamination, the light absorptive layer having a viscosity in a range of about 50,000 cps to 200,000 cps under laminating conditions, thereby defining interstitial regions between adjacent waveguides and the light absorptive layer, the interstitial regions having a lower refractive index than the waveguides.

6. The method of claim 5, wherein the second layer comprises a substantially clear layer.

7. The method of claim 5, wherein the second layer comprises a release layer that can be removed from the light absorptive layer after the laminating step.