Retroreflective articles having microcubes, and tools and methods for forming microcubes

• US 6,015,214 A
• Filed: 05/30/1996
• Issued: 01/18/2000
• Est. Priority Date: 05/30/1996
• Status: Expired

• Current Assignee: Avery Dennison Corporation
• Original Assignee: Stimsonite Corp. (Avery Dennison Corporation)
• Inventors: Couzin, Dennis I., Coman, Liviu A., Heenan, Sidney A., Montalbano, Anthony J.
• Primary Examiner(s): Phan, James
• Application Number:
  US08/655,595
• Time in Patent Office: 1,328 Days
• Field of Search: 359/529-530, 428/174, 428/221, 428/913
• US Class Current: 359/529
• CPC Class Codes: B29C 2059/023 Microembossing
• CPC Class Codes: B29C 33/301 Modular mould systems [MMS], i.e. moulds built up by stacking mould elements, e.g. plates, blocks, rods B29C33/0088 takes precedence
• CPC Class Codes: B29C 33/3842 Manufacturing moulds, e.g. shaping the mould surface by machining
• CPC Class Codes: B29C 33/42 characterised by the shape of the moulding surface, e.g. ribs or grooves
• CPC Class Codes: B29C 39/00 Shaping by casting, i.e. introducing the moulding material into a mould or between confining surfaces without significant moulding pressure; Apparatus therefor B29C41/00 takes precedence
• CPC Class Codes: B29C 43/00 Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor by liberation of internal stresses B29C61/006
• CPC Class Codes: B29D 11/00605 Production of reflex reflectors
• CPC Class Codes: B29L 2011/0091 Reflex reflectors
• CPC Class Codes: G02B 5/124 plural reflecting elements forming part of a unitary plate or sheet
• CPC Class Codes: Y10T 428/24612 Composite web or sheet
• CPC Class Codes: Y10T 428/249921 Web or sheet containing structurally defined element or component

Abstract

A method for tooling a pattern of retroreflective microcubes, which pattern can be subdivided into smaller increments within which there are straight line tooling paths, none of which pass through an otherwise solid part of the incremental pattern. The tooling paths within the various increments need not be parallel to a common plane. Various adaptions of the method enable the tooling of a number of specific microcube shapes and for modifying such optical properties of the microcubes as entrance angularity, incidence angularity, orientation angularity, observation angularity, percent active aperture and retroreflectance. Specific techniques govern the pre-selection of cube parameters such as cube axis cant, cube apex decentration, and cube boundary proportions, which parameters can be adjusted independently of each other. Designs tooled by the method can have 100% active aperture at near zero degrees entrance angle. The method involves providing a plurality of plates of micro thickness, each plate having at least one end comprised of a material that can be tooled with polished surfaces by means of an appropriate tool, tooling on said end of each plate an increment of the pattern, and assembling the plates together in various ways to form a master. Retroreflective articles made by means of this technique are expected to provide superior performance when used in pavement markers, highway signs and other applications.

Claims

1. An article comprising an array of microcubes, such that for every plane in space there are two adjacent microcubes for which at the place of adjacency none of the face edges is parallel to that plane, and in which at least one microcube of said array is rectangular or pentagonal, said at least one microcube of said array being canted face-more-parallel.

2. The article of claim 1 in which at least one microcube of said array has a plane of symmetry in which lies the cube axis of said microcube, thereby increasing the entrance angularity of said array in a plane perpendicular to said plane of symmetry.

3. An article comprising an array of microcubes, such that for every plane in space there are two adjacent microcubes for which at the place of adjacency none of the face edges is parallel to that plane, in which at least one of said microcube shape is rectangular, and in which at least one face of said rectangular microcube is pentagonal.

4. An article comprising an array of microcubes in which every three by three subarray of microcubes is nonrulable, and in which at least one microcube in a said three by three subarray of microcubes is rectangular or pentagonal, said at least one microcube being canted face-more-parallel.

5. The article of claim 4 in which at least one microcube of said array has a plane of symmetry in which lies the cube axis with said microcube, thereby increasing the entrance angularity of said array in a plane perpendicular to said plane of symmetry.