Method and apparatus for producing a relief pattern with a microscopic structure, in particular having an optical diffraction effect
First Claim
1. A method of embossing a pattern, having a microscopic relief structure of the type which produces an optical diffraction effect, onto the surface of a layer of thermoplastic material comprising the steps of:
- a. placing a flexible embossing die, in the form of a foil, bearing a microscopic relief structure to be reproduced in the thermoplastic layer, in closely-spaced but not touching relationship with said layer of thermoplastic material;
b. applying an embossing pressure to a small, substantially circular region, of said flexible embossing die, whereby said region of said flexible embossing die is brought into embossing contact with a correspondingly small, substantially circular region of said thermoplastic layer;
c. placing a radiant source of thermal energy so that said thermoplastic layer is between said flexible embossing die and said radiant source of thermal energy;
d. focussing said thermal energy onto a focal spot in the region of said thermoplastic layer which is in embossing contact with said flexible embossing die, thereby causing said region of said thermoplastic layer to heat up and soften;
e. interrupting said thermal energy, whereby said small substantially circular region of said thermoplastic layer is allowed to cool and harden, thereby fixing said microscopic relief structure in said small, substantially circular region of said thermoplastic layer;
f. removing said embossing pressure from said small, substantially circular region of said flexible embossing die, whereby embossing contact with said small substantially circular region of said thermoplastic layer is ended; and
g. repeating above steps as many times and in as many regions of said thermoplastic layer as is required to form the desired pattern.
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Accused Products
Abstract
A method and apparatus for embossing a pattern having a microscopic relief structure, such as, for example, an optical diffraction grating, onto a layer of thermoplastic material is disclosed. A small circular region of a flexible embossing die is pressed against the thermoplastic layer by means of a punch. A fraction of the corresponding small circular region of the thermoplastic layer is then heated from the rear by a beam of radiant energy. The process may be repeated at all points on the thermoplastic layer where the pattern is desired.
101 Citations
16 Claims
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1. A method of embossing a pattern, having a microscopic relief structure of the type which produces an optical diffraction effect, onto the surface of a layer of thermoplastic material comprising the steps of:
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a. placing a flexible embossing die, in the form of a foil, bearing a microscopic relief structure to be reproduced in the thermoplastic layer, in closely-spaced but not touching relationship with said layer of thermoplastic material; b. applying an embossing pressure to a small, substantially circular region, of said flexible embossing die, whereby said region of said flexible embossing die is brought into embossing contact with a correspondingly small, substantially circular region of said thermoplastic layer; c. placing a radiant source of thermal energy so that said thermoplastic layer is between said flexible embossing die and said radiant source of thermal energy; d. focussing said thermal energy onto a focal spot in the region of said thermoplastic layer which is in embossing contact with said flexible embossing die, thereby causing said region of said thermoplastic layer to heat up and soften; e. interrupting said thermal energy, whereby said small substantially circular region of said thermoplastic layer is allowed to cool and harden, thereby fixing said microscopic relief structure in said small, substantially circular region of said thermoplastic layer; f. removing said embossing pressure from said small, substantially circular region of said flexible embossing die, whereby embossing contact with said small substantially circular region of said thermoplastic layer is ended; and g. repeating above steps as many times and in as many regions of said thermoplastic layer as is required to form the desired pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of embossing a pattern, having a microscopic relief structure of the type which produces an optical diffraction effect, onto the surface of a substrate covered with a layer of radiant energy absorbing thermoplastic material comprising the steps of:
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(a) placing a flexible embossing die, in the form of a foil, bearing a microscopic relief structure to be reproduced in the thermoplastic layer, in closely-spaced but not touching relationship with said layer of thermoplastic material; (b) applying pressure to said embossing die, whereby said flexible embossing die is brought into contact with said thermoplastic layer and an elastic deformation occurs; (c) placing a radiant source of thermal energy so that said thermoplastic layer is between said flexible embossing die and said radiant source of thermal energy; (d) focussing said thermal energy through said transparent pressure plate and substrate in a small region of said radiation absorbent thermoplastic layer which is in contact with said flexible embossing die, thereby causing said region of said thermoplastic layer to heat up, soften and to be plastically deformed; (e) interrupting said thermal energy, whereby said small region of said thermoplastic layer is allowed to cool and harden, thereby fixing said microscopic relief structure in the form of an approximately circular surface region of said thermoplastic layer; (f) removing pressure from said flexible embossing die, whereby contact with said small substantially circular region of said thermoplastic layer is ended; and (g) repeating steps d and e as many times and in as many regions of said thermoplastic layer as is required to form the desired pattern. - View Dependent Claims (9, 10, 11, 12)
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- 13. An apparatus for embossing a pattern having a microscopic relief structure of the type which produces an optical diffraction effect, onto the surface of a substrate covered with a layer of radiant energy absorbing thermoplastic material, said apparatus comprising a flat, rigid and optically transparent pressure plate capable of supporting said substrate and said radiant energy absorbing thermoplastic layer, a flexible embossing die spaced apart from said pressure plate for receiving said substrate, said embossing die being capable of being placed on said thermoplastic layer of said substrate, but not in embossing contact with said thermoplastic layer, a punch located on the other side of said flexible embossing die from said substrate, a radiant energy beam source located on the other side of said pressure plate from said substrate, focussing means located between said radiant energy beam source and said pressure plate capable of producing a focal spot of said beam source on said substrate, said focal spot heating a circular surface element of said thermoplastic layer on said substrate, said punch having a convex surface and being capable of being positioned so as to produce through said embossing die an embossing pressure only in the region of said focal spot onto said thermoplastic layer, said embossing die and said substrate with said thermoplastic layer being capable of being displaced, in a plane parallel to said thermoplastic layer, relative to said focal spot and said punch.
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16. An apparatus for embossing a pattern having microscopic relief structure of the type which produces an optical diffraction effect onto the surface of a substrate covered with radiant energy absorbing thermoplastic material, said apparatus comprising a flat, rigid optically transparent pressure plate capable of supporting said substrate with a radiant-energy absorbing thermoplastic layer, a flexible embossing die spaced apart from said pressure plate by said substrate and capable of being positioned on said thermoplastic layer of said substrate, a punch located on the other side of said flexible embossing die from said substrate being capable of pressing the flexible embossing die onto said thermoplastic layer so that only an elastic deformation on the surface of said thermoplastic layer occurs, a radiation energy beam source located on the other side of said pressure plate from said substrate, focussing means located between said radiation-energy beam source and said pressure plate capable of concentrating the energy of said beam source in a focal spot through the pressure plate on through said substrate in said thermoplastic layer and heating a small region of thermoplastic layer on said substrate so that said thermoplastic layer softens and yields to said embossing die under the pressure of said punch by a plastic deformation, whereby the embossing occurs only in the region of said focal spot, said flexible embossing die and said substrate with said thermoplastic layer capable of being displaced in a plane parallel to said thermoplastic layer relative to said focal spot and said punch.
Specification