Projection-type display devices with reduced speckle

Abstract

Described herein are display devices that provide projection-type video output and use lasers to generate light. To reduce any speckle effects for a projected image cast by a projector onto of a non-specular surface, the present invention decreases coherence of the laser-generated light. Coherence reduction is accomplished by introducing a coherence diffuser in a light path of the laser light. Arranging the coherence diffuser in an unfocused light beam reduces both temporal and spatial coherence in the light. Arranging the rotating diffuser at the focus of a beam reduces only the temporal coherence while maintaining the spatial coherence.

Description

CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority under U.S.C. §120 from co-pending U.S. patent application Ser. No. 10 / 891,840, filed Jul. 15, 2004 and entitled, “POSITIONABLE PROJECTION DISPLAY DEVICES”, which is incorporated herein for all purposes; the patent application Ser. No. 10 / 891,840 also claimed under 35 U.S.C. §119(e) from co-pending U.S. Provisional Patent Application No. 60 / 487,868 filed Jul. 16, 2003, which is incorporated by reference herein for all purposes; the patent application Ser. No. 10 / 891,840 also claims priority under 35 U.S.C. §119(e) from co-pending U.S. Provisional Patent Application No. 60 / 487,871 filed Jul. 16, 2003, which is incorporated by reference herein for all purposes; the patent application Ser. No. 10 / 891,840 also claims priority under 35 U.S.C. §119(e) from co-pending U.S. Provisional Patent Application No. 60 / 487,691 filed Jul. 16, 2003, which is incorporated by reference herein for all purposes; the patent appl...

AI Technical Summary

Benefits of technology

"The present invention relates to a display device that uses diode lasers to generate video output. The device includes multiple laser sets, each with a different wavelength range for producing light. The light is then transmitted through an optical modulation device and a projection lens system for display. The invention also includes a method for producing light in a more efficient way by using a smaller number of lasers than the total number needed. The technical effects of the invention include improved video output and reduced energy consumption."

Problems solved by technology

One problem with a white-light emitting lamp is lifetime.

Not only does a lamp burn out after about two thousand hours, but luminous power consistency often declines with lamp age.

The high price of currently available projectors—and the cost of replacement lamps—compromises market acceptance and projector sales.

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