Projection screen

Claim 2

In a projection screen comprising means defining a plurality of contiguous optical microelements arranged in rectilinear rows, each of such microelements being adapted to redistribute incident image flux throughout a predefined audience volume, the improvement wherein said microelements randomly vary in size, within a predefined size range, and are of substantially identical optical power.

Claim 3

The invention according to claim 1 wherein the size of all microelements is within + or - 20 percent of a mean size.

Claim 4

The invention according to claim 1 wherein said optical microelements are alternately concave and convex in shape along said rows.

Claim 5

The invention according to claim 1 wherein said microelements are contoured to distribute image flux in such a manner that substantially constant luminance is produced throughout predefined horizontal and vertical audience angles.

Claim 6

The invention according to claim 1 wherein said screen surface is cylindrically curved about a line spaced from said screen surface and extending perpendicular to the groove length.

Claim 7

The invention according to claim 1 wherein said surface is cylindrically curved about a line remote from the screen surface and extending parallel to the groove length.

Claim 8

The invention according to claim 1 wherein said surface is spherically curved to converge the optical axes of all microelements at a point remote from the screen surface.

Claim 9

The invention according to claim 1 wherein said surface is reflective to image flux.

Claim 10

The invention according to claim 1 wherein said surface is substantially transparent to image flux.

Claim 11

In a projection screen surface comprising means defining a plurality of contiguous rectilinear grooves, the depth of each of such grooves varying along the groove length to define a row of contiguous optical microelements, the improvement wherein said groove depth varies along the row at a random spatial frequency, within a predefined spatial frequency range, to define rectilinear rows of contiguous optical microelements which randomly vary in size, within a predefined size range.

Claim 12

In a projection screen surface comprising means defining a plurality of contiguous rectilinear grooves, the depth of each of such grooves varying along the groove length to define a row of contiguous optical microelements, the improvement wherein said groove depth varies along the row at a random spatial frequency, within a predefined spatial frequency range, to define rectilinear rows of contiguous optical microelements which randomly vary in size, within a predefined size range.

Claim 13

The invention accordinG to claim 10 wherein said groove depth varies in such a manner that each of said microelements has a height, measured in a direction normal to the screen surface, proportional to the length thereof, measured along the groove length, whereby all microelements have substantially identical optical power.

Claim 14

The invention according to claim 10 wherein said groove depth undulates at a random spatial frequency to define rows of alternately concave and convex optical microelements.

Claim 15

The invention according to claim 10 wherein the transverse and longitudinal cross sections of each of said grooves is contoured such that each of said microelements redistributes image flux in such a manner that substantially constant luminance is produced throughout a predefined audience volume.

Claim 16

In a projection screen having a surface comprising means defining a plurality of contiguous rectilinear grooves, each groove having a depth which undulates along the groove length to define a row of contiguous optical microelements, the improvement wherein said groove depth varies along the groove length at a random spatial frequency, within a predefined spatial frequency range, and in such a manner as to define contiguous optical microelements of random sizes, within a predefined size range, and of substantially identical image flux-distributing power, each of said microelements being contoured to redistribute normally incident image flux throughout a predefined audience space, bounded in a plane transverse to said groove length and normal to said screen surface by audience angles A and B, measured from a normal to said surface, and having a cross section substantially defined by at least a segment of a first curve u + or - g(w;n) + or - ( Square Root 1+w ( Square Root -w -2n) + cos 1 Square Root -w) where n is the refractive index of said microelement (n being -1 when said microelement is reflective); u and w are the coordinates of said microelement, w being measured in a direction parallel to the path of incident radiation, and u being measured in the plane of the cross section, perpendicular to w; and w has a value within the following limits: -1 < or = w < or = cos2 B; when g(w;n) is positive and said microelement is refractive and when g(w;n) is negative and said microelement is reflective; and -1 < or = w < or = cos2 A; when g(w;n) is negative and said microelement is refractive and when g(w;n) is positive and said microelement is reflective, whereby each of said optical microelements produce substantially uniform luminance in said plane between said audience angles.

Claim 17

In a projection screen having a surface comprising means defining a plurality of contiguous rectilinear grooves, each groove having a depth which undulates along the groove length to define a row of contiguous optical microelements, the improvement wherein said groove depth varies along the groove length at a random spatial frequency, within a predefined spatial frequency range, and in such a manner as to define contiguous optical microelements of random sizes, within a predefined size range, and of substantially identical image flux-distributing power, each of said microelements being contoured to redistribute normally incident image flux throughout a predefined audience space, bounded in a plane transverse to said groove length and normal to said screen surface by audience angles A and B, measured from a normal to said surface, and having a cross section substantially defined by at least a segment of a first curve u + or - g(w;n) + or - ( Square Root 1+w ( Square Root -w -2n) + cos 1 Square Root -w) where n is the refractive index of said microelement (n being -1 when said microelement is reflective); u and w are the coordinates of said microelement, w being measured in a direction parallel to the path of incident radiation, and u being measured in the plane of the cross section, perpendicular to w; and w has a value within the following limits: -1 < or = w < or = cos2 B; when g(w;n) is positive and said microelement is refractive and when g(w;n) is negative and said microelement is reflective; and -1 < or = w < or = cos2 A; when g(w;n) is negative and said microelement is refractive and when g(w;n) is positive and said microelement is reflective, whereby each of said optical microelements produce substantially uniform luminance in said plane between said audience angles.

Claim 18

The invention according to claim 14 wherein each of said microelements has a longitudinal cross section substantially defined by at least a segment of said first curve where A and B are measured in the plane of said longitudinal cross section, and by at least a segment of a second curve u + or - f(w;n) + or - Square Root 1-w ( Square Root w - 2n) + cos 1 Square Root w) where w has a value within the following limits: cos2 A < or = w < or = 1, when f(w;n) is positive and said microelement is refractive and when f(w;n) is negative and said microelement is reflective; and cos2 B < or = w < or = 1, when f(w;n) is negative and said microelement is refractive and when f(w;n) is positive and said microelement is reflective.

Claim 19

The invention according to claim 14 wherein said surface is substantially spherically curved to converge the optical axes of all microelements at a point remote from said screen surface.

Claim 20

In a rear projection screen for presenting an image projected thereon to a predefined audience space, the screen comprising a sheet of substantially transparent material having first and second surfaces extending in substantially parallel planes, the first surface comprising means defining a plurality of contiguous optical microelements for distributing image flux to an audience area, the microelements being arranged in rectilinear rows, the improvement wherein said microelements randomly vary in size, within a predefined size range, and are of substantially identical optical power, and said second surface comprises means defining a Fresnel-type lens for controlling the angle at which image flux impinges upon said microelements.

Claim 21

In a rear projection screen for presenting an image projected thereon to a predefined audience space, the screen comprising a sheet of substantially transparent material having first and second surfaces extending in substantially parallel planes, the first surface comprising means defining a plurality of contiguous optical microelements for distributing image flux to an audience area, the microelements being arranged in rectilinear rows, the improvement wherein said microelements randomly vary in size, within a predefined size range, and are of substantially identical optical power, and said second surface comprises means defining a Fresnel-type lens for controlling the angle at which image flux impinges upon said microelements.

Claim 22

The invention according to claim 17 wherein said optical microelements are alternately concave and convex in shape along said rows.

Claim 23

The invention according to claim 17 wherein said microelements are contoured to distribute normally incident image flux in such a manner that substantially constant luminance is produced throughout said audience area.