EP0342958A2 — High efficiency cube-corner retroreflective mater…

Claim 1

Independent Claim 229 words

A retroreflective material comprising a transparent surface layer having a front side and a back side and an array of cube-corner retroreflective elements, characterized in that each of said reflecting elements includes: (a) a rectangular base on the back side of the surface layer, (b) two rectangular faces approximately perpendicular to each other, each one being joined to an edge of the rectangular base to form a reflecting element having a triangular cross section; and (c) two triangular faces that are approximately parallel to each other and approximately perpendicular to said rectangular faces, and forming the ends of the reflecting elements; said triangular and said rectangular faces defining a pair of cube-corners therebetween; said reflecting elements being formed by two approximately perpendicular sets of parallel grooves, a first set of V-shaped grooves, and a second set of grooves having a pair of faces nearly perpendicular to said rectangular base, at least one of the sets of grooves including more than one groove having a groove side angle that differs from another groove side angle of the same set by a small amount less than 3°, whereby the array of cube-corner retroreflective elements is characterized by small variations in at least one of the dihedral angles between the faces from one reflecting element to another, said variations existing in at least some but not necessarily all of the reflecting elements.

Claim 2

Dependent Claim 229 words

A retroreflective material comprising a transparent surface layer having a front side and a back side and an array of cube-corner retroreflective elements, characterized in that each of said reflecting elements includes: (a) a rectangular base on the back side of the surface layer, (b) two rectangular faces approximately perpendicular to each other, each one being joined to an edge of the rectangular base to form a reflecting element having a triangular cross section; and (c) two triangular faces that are approximately parallel to each other and approximately perpendicular to said rectangular faces, and forming the ends of the reflecting elements; said triangular and said rectangular faces defining a pair of cube-corners therebetween; said reflecting elements being formed by two approximately perpendicular sets of parallel grooves, a first set of V-shaped grooves, and a second set of grooves having a pair of faces nearly perpendicular to said rectangular base, at least one of the sets of grooves including more than one groove having a groove side angle that differs from another groove side angle of the same set by a small amount less than 3°, whereby the array of cube-corner retroreflective elements is characterized by small variations in at least one of the dihedral angles between the faces from one reflecting element to another, said variations existing in at least some but not necessarily all of the reflecting elements.

Claim 3

Dependent Claim 35 words

The retroreflective material of claim 1 further characterized in that both sets of grooves include more than one groove having a groove side angle that differs from another groove side angle of the same set.

Claim 4

Dependent Claim 57 words

The retroreflective material of claim 1 further characterized in that the differences in groove side angles occur in a repeating pattern, whereby the array of cube-corner retroreflective elements is divided into repeating sub-arrays that each comprise a plurality of cube-corner retroreflective elements in a plurality of distinctive shapes that retroreflect incident light in distinctively shaped light patterns.

Claim 5

Dependent Claim 28 words

The retroreflective material of any one of claims 1-4 further characterized in that said material further comprises a backing layer sealed to the back of the retroreflective material.

Claim 6

Dependent Claim 24 words

The retroreflective material of any one of claims 1-5 further characterized in that the groove side angle differs by an amount less than 1°.

Claim 7

Dependent Claim 48 words

The retroreflective article of any one of claims 1-2 further characterized in that the cube-corner retroreflective elements of the array of elements are arranged in pairs of elements, so that each distinctively shaped element is matched by a similarly shaped element rotated 180 degrees from the first element.

Claim 8

Dependent Claim 152 words

A retroreflective material comprising a transparent surface layer having a front side and a back side and an array of cube-corner reflecting elements, characterized in that each of said reflecting elements includes: (a) a rectangular base on the back side of the surface layer; (b) two mutually substantially perpendicular rectangular faces, each one being joined to an edge of the rectangular base to form a reflecting element having a triangular cross section; and (c) two substantially parallel triangular faces perpendicular to said rectangular faces; said triangular and rectangular faces defining a pair of cube-corners therebetween, each pair of said rectangular faces defining an angle of intersection having a bisector which intersects said base, said bisector forming an angle Beta with a line perpendicular to said base, said reflective material including perpendicular bisector elements, wherein Beta is substantially zero, and canted bisector elements wherein Beta is about 0° to less than about 45°.

Claim 9

Dependent Claim 152 words

A retroreflective material comprising a transparent surface layer having a front side and a back side and an array of cube-corner reflecting elements, characterized in that each of said reflecting elements includes: (a) a rectangular base on the back side of the surface layer; (b) two mutually substantially perpendicular rectangular faces, each one being joined to an edge of the rectangular base to form a reflecting element having a triangular cross section; and (c) two substantially parallel triangular faces perpendicular to said rectangular faces; said triangular and rectangular faces defining a pair of cube-corners therebetween, each pair of said rectangular faces defining an angle of intersection having a bisector which intersects said base, said bisector forming an angle Beta with a line perpendicular to said base, said reflective material including perpendicular bisector elements, wherein Beta is substantially zero, and canted bisector elements wherein Beta is about 0° to less than about 45°.

Claim 10

Dependent Claim 25 words

The retroreflective material of claim 7 further characterized in that said canted bisector elements each have an angle Beta which is substantially the same angle.

Claim 11

Dependent Claim 22 words

The retroreflective material of claim 7 further characterized in that the angle Beta for each of said canted bisector elements varies randomly.

Claim 12

Dependent Claim 25 words

The retroreflective material of claim 7 further characterized in that the angle Beta for each of said canted bisector elements varies in a uniform pattern.

Claim 13

Dependent Claim 273 words

A retroreflective material comprising a transparent surface layer having a front side and a back side and an array of cube-corner reflecting elements, characterized in that each of said reflecting elements includes: (a) a rectangular base on the back side of the surface layer; (b) two approximately mutually perpendicular rectangular faces, each being joined to an edge of the rectangular base to form a reflecting element having a triangular cross section; and (c) two triangular faces that are approximately parallel to each other and approximately perpendicular to said rectangular faces; said triangular and rectangular faces defining a pair of cube-corners therebetween; said reflecting elements being formed by two perpendicular sets of parallel grooves, a first set of V-shaped grooves, and a second set of grooves having a pair of faces nearly perpendicular to said rectangular base, at least one of the sets of grooves including more than one groove having a groove side angle that differs from another groove side angle of the same set by a small amount less than 3°, whereby the array of cube-corner retroreflective elements is characterized by small variations in at least one of the dihedral angles between the faces from one reflecting element to another, said variation existing in at least some but not necessarily all of the reflecting elements; each pair of said rectangular faces defining an angle of intersection having a bisector which intersects said base, said bisector forming an angle Beta with a line perpendicular to said base, said reflective material including perpendicular bisector elements, wherein Beta is substantially zero and canted bisector elements wherein Beta is about 0° to less than about 45°.

Claim 14

Dependent Claim 273 words

A retroreflective material comprising a transparent surface layer having a front side and a back side and an array of cube-corner reflecting elements, characterized in that each of said reflecting elements includes: (a) a rectangular base on the back side of the surface layer; (b) two approximately mutually perpendicular rectangular faces, each being joined to an edge of the rectangular base to form a reflecting element having a triangular cross section; and (c) two triangular faces that are approximately parallel to each other and approximately perpendicular to said rectangular faces; said triangular and rectangular faces defining a pair of cube-corners therebetween; said reflecting elements being formed by two perpendicular sets of parallel grooves, a first set of V-shaped grooves, and a second set of grooves having a pair of faces nearly perpendicular to said rectangular base, at least one of the sets of grooves including more than one groove having a groove side angle that differs from another groove side angle of the same set by a small amount less than 3°, whereby the array of cube-corner retroreflective elements is characterized by small variations in at least one of the dihedral angles between the faces from one reflecting element to another, said variation existing in at least some but not necessarily all of the reflecting elements; each pair of said rectangular faces defining an angle of intersection having a bisector which intersects said base, said bisector forming an angle Beta with a line perpendicular to said base, said reflective material including perpendicular bisector elements, wherein Beta is substantially zero and canted bisector elements wherein Beta is about 0° to less than about 45°.

Claim 15

Dependent Claim 20 words

The retroreflective material of claim 11 further characterized in that the differences in groove side angles occur in repeating patterns.

Claim 16

Dependent Claim 25 words

The retroreflective material of claim 12 further characterized in that said canted bisector elements each have an angle Beta which is substantially the same angle.

Claim 17

Dependent Claim 27 words

The retroreflective material of any of claims 11-13 further characterized in that said material further comprises a backing layer sealed to the back of the retroreflective material.

Claim 18

Independent Claim 83 words

A method for preparing a tool from which cube-corner retroreflective articles are formed characterized 'in that said method comprises forming in tool stock at least two sets of a plurality of parallel grooves that define at least some lateral faces of the cube-corner elements; the grooves within at least one set being formed with variation in the groove side angles from one groove to the next groove by a small amount, said variation existing among a plurality of the grooves within the set.

Claim 19

Independent Claim 83 words

A method for preparing a tool from which cube-corner retroreflective articles are formed characterized 'in that said method comprises forming in tool stock at least two sets of a plurality of parallel grooves that define at least some lateral faces of the cube-corner elements; the grooves within at least one set being formed with variation in the groove side angles from one groove to the next groove by a small amount, said variation existing among a plurality of the grooves within the set.

Claim 20

Dependent Claim 20 words

The method of claim 15 further characterized in that said variation in groove side angles occurs in a repeating pattern.

Claim 21

Dependent Claim 66 words

The method of claim 16 further characterized in that a groove side angle of some repeated grooves across the set of grooves is varied to an angle greater than the angle required to provide orthogonal cube-corner elements, and a groove side angle in other repeated grooves across the set of grooves is varied to an angle less than the angle required to provide orthogonal cube-corner elements.

Claim 22

Independent Claim 50 words

The method of any of claims 15-17 further characterized in that one of the sets of grooves comprises V-shaped grooves and another set formed perpendicular to said first set of grooves comprises grooves having a right angle channel cross section having walls approximately perpendicular to the bottom of the groove.

Claim 23

Dependent Claim 67 words

The method of claim 15 further characterized in that said method further comprises forming a third set of a plurality of parallel grooves which intersect the other two sets of grooves at the points where they intersect, forming a multiplicity of common points of intersection among the three sets of grooves, said third set of grooves partly defining the cube-corner elements, in conjunction with the other grooves.

Claim 24

Independent Claim 97 words

A method for preparing a tool from which cube-corner retroreflective articles are formed characterized in that said method comprises configuring the surface of tool stock with a surface that defines an array of cube-corner retroreflective elements to be included in the article, the configured surface including at least one set of parallel V-shaped grooves that define at least some lateral faces of the cube-corner elements of the article, at least a plurality of the groove side angles of the set being varied to angles different by predetermined amounts from the angles required to provide orthogonal cube-corner elements.

Claim 25

Independent Claim 97 words

A method for preparing a tool from which cube-corner retroreflective articles are formed characterized in that said method comprises configuring the surface of tool stock with a surface that defines an array of cube-corner retroreflective elements to be included in the article, the configured surface including at least one set of parallel V-shaped grooves that define at least some lateral faces of the cube-corner elements of the article, at least a plurality of the groove side angles of the set being varied to angles different by predetermined amounts from the angles required to provide orthogonal cube-corner elements.

Claim 26

Dependent Claim 77 words

The method of claim 20 further characterized in that the configured surface includes a second set of grooves perpendicular to the first set of grooves, the second set of grooves having a right angle channel cross section having walls approximately perpendicular to the bottom of the groove, at least a plurality of the groove side angles of the second set being varied to angles different by predetermined amounts from the angles required to provide orthogonal cube-corner elements.

Claim 27

Dependent Claim 64 words

The method of claim 20 further characterized in that the configured surface includes two other sets of parallel V-shaped grooves, all three sets interacting so as to define cube-corner retroreflective elements, and at least a plurality of the groove side angles of the second and third sets being varied to angles different by predetermined amounts from the angles required to provide orthogonal cube-corner elements.

High efficiency cube-corner retroreflective material

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