Curtain for shrouding welding operations

Claim 2

A curtain for protecting an observer from damage by light from welding arcs, said curtain being sufficiently transparent to see through it an object of substantial size, said curtain comprising: an organic plastic matrix material which itself is inherently transparent and which is formed into a sheet with a pair of surfaces and a dimension of thickness between said surfaces; and dye distributed throughout said matrix material, said dye being provided in concentrations which permit the sheet to transmit at least 70% of the radiation incident upon it which has wavelengths between about 600 nm and about 1,400 nm, the relative transmission of said sheet with dye being no greater than 0.01 at 450 nm, no greater than 0.05 at 491 nm, and at least 0.70 at 600 nm.

Claim 3

A curtain according to claim 1 in which said dye is selected from the group consisting of fluorescent dyes which radiate substantial light in wavelengths between about 450 nm and 700 nm, metallic azo dyes, and combina-tions thereof.

Claim 4

A curtain according to claim 1 in which discontinuities are dis-tributed throughout the matrix material, said discontinuities having an optical index of refraction which differs from the optical index of refraction of the matrix material by at least 0.2 units, whereby to scatter at least 5% and less than 50% of the light which passes through the sheet.

Claim 5

A curtain according to claim 1 in which one of said surfaces is formed with a plurality of declivities having faces disposed at angles to the plane of the sheet, whereby some rays of light which passes through said one surface are refracted and undergo a change in direction.

Claim 6

5, A curtain according to claim 3 in which one of said surfaces is formed with a plurality of declivities having faces disposed at angles to the plane of the sheet, whereby some rays of light which passes through said one surface are refracted and undergo a change in direction.

Claim 7

A curtain according to claim 2 in which discontinuities are distri-buted throughout the matrix material, said discontinuities having an optical index of refraction which differs from the optical index of refraction of the matrix material by at least 0.2 units, whereby to scatter at least 5% and less than 50% of the light which passes through the sheet.

Claim 8

A curtain of substantial area for forming at least a portion of the perimeter of an area in which an electrical arc welding or an electrical arc cutting operation is conducted, for the purpose of protecting the eyes of an observer located outside of said perimeter from damage by light from said arcs, said curtain comprising: an organic plastic matrix material which itself is inherently transpar-ent and which is formed into a sheet with a pair of surfaces and a dimension of thickness between said surfaces; an ultraviolet absorber distributed throughout said matrix material; and dye distributed throughout said matrix material, said dye, being of the class, and being present in concentrations, which permit the sheet to transmit at least 70% of the radiation incident upon it which has wavelengths between about 600 nm and about 1,400 nm, the relative transmissions of said sheet with dye being no greater than 0.01 at 450 nm, no greater than 0.05 at 491 nm, and at least 0.70 at 600 nm, said curtain being sufficiently clear for said observer to see through it an object of substantial size located inside said perimeter.

Claim 9

A curtain of substantial area for forming at least a portion of the perimeter of an area in which an electrical arc welding or an electrical arc cutting operation is conducted, for the purpose of protecting the eyes of an observer located outside of said perimeter from damage by light from said arcs, said curtain comprising: an organic plastic matrix material which itself is inherently transpar-ent and which is formed into a sheet with a pair of surfaces and a dimension of thickness between said surfaces; an ultraviolet absorber distributed throughout said matrix material; and dye distributed throughout said matrix material, said dye, being of the class, and being present in concentrations, which permit the sheet to transmit at least 70% of the radiation incident upon it which has wavelengths between about 600 nm and about 1,400 nm, the relative transmissions of said sheet with dye being no greater than 0.01 at 450 nm, no greater than 0.05 at 491 nm, and at least 0.70 at 600 nm, said curtain being sufficiently clear for said observer to see through it an object of substantial size located inside said perimeter.

Claim 10

A curtain according to claim 1 or 7 in which the said curtain additionally includes a fire retardant.

Claim 11

A combination according to claim 7 in which said dye is selected from a group consisting of flourescent dyes which radiate substantial light in wavelengths between about 450 nm and 700 nm, metallic azo dyes, and combinations thereof.

Claim 12

A combination according to claim 1 or 7 in which said dye is metallic azo dye.

Claim 13

A combination according to claim 1 or 7 in which said dye is a fluorescent dye that radiates substantial light in wavelengths between about 450 nm and about 700 nm and is migratory in said matrix material.

Claim 14

A combination according to claim 7 in which discontinuities are distributed throughout the matrix material, said discontinuities having an optical index of refraction which differs from the optical index of refrac-tion of the matrix material by at least 0.2 units, and being present in such condition and quantities as to scatter at least 5% and less than 50% of the light which passes through the sheet whereby to cause a decrease in scene contrast.

Claim 15

A combination according to claim 3, 6 or 12 in which said discon-tinuities are of a size approximating 500 nm, whereby preferentially to scatter radiation of this wavelength.

Claim 16

A combination according to claim 3, 6 or 12 in which said discon-tinuities are selected from the group consisting of air bubbles, zinc oxide powder, fluorescent zinc oxide powder, titanium-dioxide powder, and mixtures thereof.

Claim 17

A combination according to claim 3, 6 or 12 in which said discon-tinuities are zinc oxide powder.

Claim 18

A combination according to claim 3, 6 or 12 in which said discon-tinuities are fluorescent zinc oxide powder, whereby to function as an ultra-violet absorber, fluorescent light source, and scattering means.

Claim 19

A combination according to claim 3, 6 or 12 in which said discon-tinuities are titanium-dioxide powder.

Claim 20

A combination according to claim 7 in which one of said surfaces is formed with a plurality of declivities having faces disposed at angles to the plane of the sheet, whereby some rays of light which pass through said one surface are refracted and undergo a change in direction.

Claim 21

A combination according to claim 9 in which discontinuities are distributed throughout the matrix material, said discontinuities having an optical index of refraction which differs from the optical index of refraction of the matrix material by at least 0.2 units, and being present in such con-centrations and quantities as to scatter at least 5% and less than 50% of the light which passes through the sheet, whereby to cause a decrease in scene contrast.

Claim 22

A combination according to claim 19 in which said discontinuities are of a size approximating 500 nm, whereby preferentially to scatter radiation of this wavelength.

Claim 23

A combination according to claim 19 in which said fluorescent dye is migratory in said matrix material.

Claim 24

A combination according to claim 9 in which one of said surfaces is formed with a plurality of declivities having faces disposed at angles to the plane of the sheet, whereby some rays of light which pass through said one surface are refracted and undergo a change in direction.

Claim 25

A combination according to claim 4, 18 or 22 in which said ankles are less than about 8 minutes of arc.

Claim 26

A combination according to claim 4, 18 or 22 in which the declivities have non-planar surfaces.

Claim 27

A combination according to claim 4, 18 or 22 in which said declivi-ties are formed by reticulation.

Claim 28

A combination according to claim 4, 18 or 22 in which said declivi-ties are formed on both surfaces of the curtain, the said angles being less than about four minutes of arc.

Claim 29

A combination according to claim 12 in which one of said surfaces is formed with a plurality of declivities having faces disposed at angles to the plane of the sheet, whereby some rays of light which pass through said one surface are refracted and undergo a change in direction.

Claim 30

A combination according to claim 19 or 27 in which said discontinui-ties are selected from the group consisting of air bubbles, zinc oxide powder, fluorescent zinc oxide powder, titanium-dioxide powder, and mixtures thereof.

Claim 31

A combination according to claim 12 or 27 in which said dye is selected from the group consisting of fluorescent dyes which radiate substan-tial light in wavelengths between about 450 nm and 700 nm, metallic azo dyes, and combinations thereof.