Differentially cured materials and process for forming same

• US 7,517,205 B2
• Filed: 07/26/2007
• Issued: 04/14/2009
• Est. Priority Date: 08/18/2000
• Status: Expired due to Fees

• Current Assignee: Orafol Americas Inc. (Orafol Europe GmbH)
• Original Assignee: Reflexite
• Inventors: Mullen, Patrick W.
• Primary Examiner(s): Gupta; Yogendra
• Assistant Examiner(s): EWALD, MARIA VERONICA
• Application Number:
  US11/881,270
• Publication Number:
  US 20070292549A1
• Time in Patent Office: 628 Days
• Field of Search: 425/174.4, 425/115, 425/363, 425/385, 425/373
• US Class Current: 425/115
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 35/0894 provided with masks or diaphragms
• CPC Class Codes: B29C 35/10 for articles of indefinite length
• CPC Class Codes: B29D 11/00 Producing optical elements, e.g. lenses or prisms grinding or polishing of optical elements B24B; constructional form of optical elements G02B; optical parts of spectacles G02C7/00
• CPC Class Codes: B29D 11/00605 Production of reflex reflectors
• CPC Class Codes: B29K 2105/243 Partially cured
• CPC Class Codes: B29K 2995/003 Reflective
• CPC Class Codes: B29L 2011/0083 Reflectors
• CPC Class Codes: G02B 5/045 Prism arrays
• CPC Class Codes: G02B 5/12 Reflex reflectors
• CPC Class Codes: G03F 7/001 Phase modulating patterns, e.g. refractive index patterns
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

A structure includes a layer which includes a first cured portion and a second cured portion which are formed from a same light curable material. The first cured portion is cured to a first amount, and the second cured portion is cured to a second amount. The first amount is sufficiently different than the second amount to result in a visible discontinuity on the surface of the structure.

A method for forming a pattern in a radiation curable material includes providing between a radiation source and the radiation curable material, a pattern that can block a portion of the radiation from the radiation source. The material is cured with radiation from the radiation source to form a pattern in the radiation curable material.

Claims

1. An apparatus for forming an optical film comprising:

a mold for defining a shape for optical structures in the optical film;

a liquid material dispenser, wherein said liquid material dispenser feeds a radiation curable liquid material to the mold;

a continuous mask film, for defining a pattern that further defines areas of the optical film where curved portions are to be made in the optical structures therein;

a continuous base film dispenser, for feeding a transparent base film between the mask film and the mold; and

a radiation source positioned for simultaneously curing and patterning the liquid material by irradiating the liquid material through the overlapping mask film and base film, such that the liquid material is cured to form the optical film, and such that the curved portions as defined by the mask film are patterned in the optical structures at the same time that they are cured, via differential exposure to the radiation in an area of the radiation curable liquid material blocked from the radiation source by the pattern.

2. The apparatus of claim 1 wherein the optical structures are formed in a surface of the optical film that is opposite a surface of the optical film that contacts the base film.

3. The apparatus of claim 1 wherein said radiation source emits ultraviolet light.

4. The apparatus of claim 1 wherein said radiation curable monomer material is selected from a material consisting of polyester, urethane, epoxy acrylates or methacrylates.

5. The apparatus of claim 1 wherein the pattern is configured in the form of a logo, geometric forms or alphanumerics.

6. The apparatus of claim 1 wherein a first cured portion has an index of refraction that is different than the index of refraction of a second cured portion.

7. The apparatus of claim 1 wherein a first cured portion has a density that is different than the density of a second cured portion.

8. An apparatus for making a continuous optical film having parallel prism structures, the apparatus comprising:

a rotating cylinder mold having linear grooves formed on an outer surface thereof, the linear grooves used as a mold for defining the parallel prism structures with aligned peaks;

a liquid material dispenser, wherein said liquid material dispenser feeds a radiation curable liquid material onto the rotating cylinder mold at a dispensing location;

a first roller, for supplying a continuous, radiation transparent optical base film;

a second roller, for supplying a continuous mask film near the dispensing location, the continuous mask film having a pattern used in further defining features of the optical base film;

a first pinch roller, for placing the continuous mask film adjacent to the continuous optical base film near the dispensing location, and for positioning the optical base film and mask film against the rotating mold such that the optical base film is positioned nearest the rotating mold and the mask film is positioned outside of the optical base film;

a radiation source, disposed after the first pinch roller, for providing radiation for simultaneously curing and patterning the liquid material by irradiating the liquid material through the adjacent mask film and optical base film, such that the radiation travels first through the mask film and then through the transparent optical base film before curing the liquid material, and such that the radiation source causes simultaneous patterning of the liquid material, to thereby define the optical base film and form deformations in the prism peaks in an area of the liquid material blocked from the irradiation by the pattern;

a second pinch roller, disposed at a second location adjacent the rotating mold, for further holding the mask film and optical base film in position with respect to the rotating mold;

a first wind-up roller, for collecting the optical base film; and

a second wind-up roller, for collecting the mask film.