US 4,787,708 AGranted

Apparatus for continuously controlled emission of light from prism light guide

AssigneeTIR Systems Ltd.

InventorLorne A. Whitehead

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Abstract

A variety of techniques are used to effect continuously controlled emission of light from a light guide. For example, the light guide may contain a mechanism formed of a substantially non-light absorptive material having a density which varies as a function of the length of the light guide. The mechansim causes light to escape from the light guide at a rate which varies along the length of the light guide, such that the amount of light escaping, per unit length, along the light guide has a selected distribution of values. Alternatively, the light guide's central path may be non-linear. As a further alternative, the average cross-sectional dimension of each of the plane segments aforesaid may be non-constant. As yet another alternative, a first portion of the light guide may comprise prism light guide material and the remaining portion may be such that a substantial portion of light incident thereupon is allowed to escape therethrough.

Claims46

Dependent claims

A light guide, having:

(i) a central path comprising the locus of points which are the centroids of the segments contained within said light guide of all planes which intersect said light guide and which are oriented such that the area of each of said plane segments is a minimum;
and,
(iii) an average cross-sectional dimension comprising, for each one of said plane segments, the average length of those portions of all lines within said light guide which lie on said one plane segment and which intersect said light guide;
wherein:
(a) the length of said light guide is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
(b) the fractional rate of change, along said light guide, of substantially all randomly selected cross-sectional dimensions of said light guide, is substantially less than the reciprocal of the average cross-sectional dimension of substantially all of said plane segments;
(c) the radius of curvature of said central path at substantially all randomly selected points on said central path is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
and,
(d) said light guide contains a mechanism which causes light to escape from said light guide at a rate which varies along the length of said light guide, such that the mount of light escaping, per unit length, along said light guide has a selected distribution of values, wherein:
(I) said mechanism is a substantially non light absorptive material;
and,
(II) the density of said material varies as a function of the length of said light guide.

9 more elements

A light guide, having:

(i) a central path comprising the locus of points which are the centroids of the segments contained within said light guide of all planes which intersect said light guide and which are oriented such that the area of each of said plane segments is a minimum;
and,
(ii) an average cross-sectional dimension comprising, for each one of said plane segments, the average length of those portions of all lines within said light guide which lie on said one plane segment and which intersect said light guide;
wherein:
(a) the length of said light guide is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
(b) the fractional rate of change, along said light guide, of substantially all randomly selected cross-sectional dimensions of said light guide, is substantially less than the reciprocal of the average cross-sectional dimension of substantially all of said plane segments;
(c) the radius of curvature of said central path at substantially all randomly selected points on said central path is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
and,
(d) said central path is non linear.

6 more elements

A light guide, having:

(i) a central path comprising the locus of points which are the centroids of the segments contained within said light guide of all planes which intersect said light guide and which are oriented such that the area of each of said plane segments is a minimum;
and,
(ii) an average cross-sectional dimension comprising, for each one of said plane segments, the average length of those portions of all lines within said light guide which lie on said one plane segment and which intersect said light guide;
wherein:
(a) the length of said light guide is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
(b) the fractional rate of change, along said light guide, of substantially all randomly selected cross-sectional dimensions of said light guide, is substantially less than the reciprocal of the average cross-sectional dimension of substantially all of said plane segments;
(c) the radius of curvature of said central path at substantially all randomly selected points on said central path is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
and,
(d) the average cross-sectional dimension of each of said plane segments is non constant.

6 more elements

A light guide, having:

(i) a central path comprising the locus of points which are the centroids of the segments contained within said light guide of all planes which intersect said light guide and which are oriented such that the area of each of said plane segments is a minimum;
and,
(ii) an average cross-sectional dimension comprising, for each one of said plane segments, the average length of those portions of all lines within said light guide which lie on said one plane segment and which intersect said light guide;
wherein:
(a) the length of said light guide is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
(b) the fractional rate of change, along said light guide, of substantially all randomly selected cross-sectional dimensions of said light guide, is substantially less than the reciprocal of the average cross-sectional dimension of substantially all of said plane segments;
(c) the radius of curvature of said central path at substantially all randomly selected points on said central path is substantially greater than the average cross-sectional dimension of substantially all of said plane segments;
(d) a first portion of said light guide comprises prism light guide material;
and,
(e) the remaining portion of said light guide allows a substantial portion of light incident thereupon to escape therethrough.

7 more elements

Dependencies are inferred from the claim text.