Optical: systems and elements – Collimating of light beam
Reexamination Certificate
1999-07-22
2001-01-30
Mack, Ricky (Department: 2873)
Optical: systems and elements
Collimating of light beam
C359S618000
Reexamination Certificate
active
06181476
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to efficient illumination of targets, as for example screens, such as liquid crystal displays.
There is need for devices of the type disclosed herein, and in particular for uniform illumination of targets, using compact high-brightness light sources. Also, there is need for light collimating devices that have minimum lens and reflector total depth, along the optical axis, and with maximum interception of light from a central source.
SUMMARY OF THE INVENTION
It is a major object of the invention to provide an improved device of the type referred to and comprising, in combination:
a) a light source,
b) a drum lens having a body extending about the light source, for refracting light from the source,
c) a light reflector extending about the drum lens body, for forwardly re-directing refracted light received from the drum lens body,
d) the drum lens and reflector defining a longitudinally forwardly extending optical axis,
e) and including an aspheric lens located longitudinally forwardly of the light source to refract light received from said source to be transmitted in a forward direction.
As will be seen, the optical axis centrally intersects the aspheric lens.
It is a further object of the invention to provide a protective, transparent envelope extending about the light source, the drum lens extending laterally about the envelope, and the aspheric lens extending longitudinally forwardly of the envelope to receive light from the source via the envelope and to collimate such light. The aspheric lens may be integral with the drum lens, with a forwardly facing land located between the drum lens and the aspheric lens.
Yet another object is to provide such an aspheric lens with an inner surface longitudinally facing the envelope, the inner surface having rearward convexity, and the aspheric lens also having an outer surface longitudinally facing away from the envelope, that outer surface having forward convexity which exceeds the convexity of the inner surface.
An additional object is to provide a local juncture between the drum lens and the aspheric lens, and located to separate light refracted by the drum lens and the aspheric lens, whereby a gap is formed between light refracted by the aspheric lens and light reflected by the reflector. As will be seen, the drum lens may advantageously have an inner substantially cylindrical surface intercepting an edge defined by said aspheric lens inner surface. Also, the drum lens may have an outer outwardly convex surface terminating outwardly of an edge defined by the aspheric lens outer surface.
A yet further object is to provide a target spaced forwardly of the aspheric lens and reflector, the target positioned to receive collimated light via the aspheric lens and reflector. The target may advantageously comprise a liquid crystal display.
A related U.S. application is Ser. No. 08/864,840, now U.S. Pat. No. 5,926,320,filed May 29, 1997.
These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following specification and drawings, in which:
REFERENCES:
patent: 4770514 (1988-09-01), Silvergate
patent: 5577493 (1996-11-01), Parkyn, Jr. et al.
patent: 5757557 (1998-05-01), Medvedev et al.
patent: 5926320 (1999-07-01), Parkyn, Jr. et al.
Medvedev Vladimir
Parkyn, Jr. William A.
Haefliger William W.
Mack Ricky
Teledyne Lighting and Display Products, Inc.
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