US 2001/0040653 A1 · REFLECTIVE FILM MATERIAL HAVING SYMMETRICAL REFLECTION CHARACTERISTICS AND METHOD AND APPARATUS FOR MAKING THE SAME

Abstract

Disclosed are novel reflective films having symmetrical reflection characteristics on the upper and lower surfaces thereof. Preferably, such films are made from cholesteric liquid crystal (CLC) material, wherein the pitch of the helices of the liquid crystal molecules therein varies along the thickness dimension (i.e. transverse to the surface) of the film. Depending on the final spiral structure of the materials utilized, the CLC circularly polarizing film materials reflect either left-handed or right-handed circularly polarized light. In a first illustrative embodiment, the CLC film has a laminated construction in order that both the upper and lower surfaces thereof have substantially the same reflection characteristics over its tuned reflection band. In second illustrative embodiment, the CLC film has a laminated construction in order that both the upper and lower surfaces thereof have substantially the same reflection characteristics over its broadband reflection band. By virtue of their circularly polarizing reflection characteristics, the CLC films of the present invention can be used to form polarization-encoded spatially multiplexed images (SMI) on radiation absorbing surfaces, coloring media with high brightness characteristics, CLC-based toner 2-D and 3-D xerographic printing processes, and the like.

Claims32

Dependent claims

Reflective film comprising:

material having upper and a lower surfaces,
wherein the reflection characteristics of said upper surface is substantially the same as the reflection characteristics of said lower surface over a prespecified band of said electromagnetic spectrum.

A method of making reflective film having symmetrical reflection characteristics over at least a portion of the visible band of the electromagnetic spectrum, said method comprising the steps of:

(a) producing a first layer of film material having upper and a lower surfaces,
wherein the reflection characteristics of said upper surface of said first layer is substantially different from the reflection characteristics of said lower surface of said first layer over the visible band of said electromagnetic spectrum;
(b) producing a second layer of film material having upper and a lower surfaces,
wherein the reflection characteristics of said upper surface of said second layer is substantially different from the reflection characteristics of said lower surface of said second layer over the visible band of said electromagnetic spectrum, and the reflection characteristics of said upper surface of said first layer is substantially similar to the reflection characteristics of said upper surface of said second layer over the visible band of said electromagnetic spectrum;
and
(c) bringing the upper surface of said first layer in physical contact with the upper surface of said second layer and laminating said layers together to produce a composite film having upper and lower surfaces,
wherein said upper and lower surfaces of said composite film have substantially similiar the reflection characteristics over at least a portion of the visible band of said electromagnetic spectrum.

4 more elements

Apparatus for making reflective film having symmetrical reflection characteristics over at least a portion of the visible band of the electromagnetic spectrum, said apparatus comprising:

film layer producing means for producing a first layer of film material having upper and a lower surfaces, and a second layer of film material having upper and a lower surfaces,
wherein the reflection characteristics of said upper surface of said first layer is substantially different from the reflection characteristics of said lower surface of said first layer over the visible band of said electromagnetic spectrum, and
wherein the reflection characteristics of said upper surface of said second layer is substantially different from the reflection characteristics of said lower surface of said second layer over the visible band of said electromagnetic spectrum, and the reflection characteristics of said upper surface of said first layer is substantially similar to the reflection characteristics of said upper surface of said second layer over the visible band of said electromagnetic spectrum;
and
film contacting means for bringing the upper surface of said first layer in physical contact with the upper surface of said second layer and laminating said layers together to produce a composite film having upper and lower surfaces,
wherein said upper and lower surfaces of said composite film have substantially similiar the reflection characteristics over at least a portion of the visible band of said electromagnetic spectrum.

3 more elements

Dependencies are inferred from the claim text.

Reflective film material having symmetrical reflection characteristics and method and apparatus for making the same

Life of this patent

Reflective film material having symmetrical reflection characteristics and method and apparatus for making the same

Life of this patent

Abstract

Claims32