Patent EP0203752A2 successfully refreshed from Google Patents.
EP0203752A2
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EP
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Transparent sheet containing directional image information and method for its production
Assignee: 3M Co
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Filing: 1986-05-12
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Granted: —
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Expires: 2006-05-12
Abstract
Abstract This invention concerns a transparent sheet containing a directional image and method for forming such a sheet. A directional image is created in a transparent sheet comprising a monolayer of microlenses by forming deformations or axial markings in at least some of the microlenses by irradiation with a laser beam. The sheet may further comprise a partially light transmissive mirror disposed behind at least some of the microlenses. The directional images may be formed in transparent sheet which has been applied to a document as an overlay. When viewed under diffuse lighting conditions, the deformations appear as a dark image. The deformations may be formed so that when viewed under retroreflective conditions within a conical field the image is darker than the surrounding background, and when viewed under retroreflective conditions outside the conical field the image is brighter than the surrounding background.
Inventors
- 👤 Gerald R. C/O Minnesota Mining And Porter
- 👤 Thomas I. C/O Minnesota Mining And Bradshaw
- 👤 Eric N. C/O Minnesota Mining And Hockert
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 15:45
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/12; G02B5/126; G02B5/128; G06; G06K; G06K19/00; G06K19/06; G06K19/08; G06K19/10; G06K19/14
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
81 words
A substantially transparent sheet comprising a monolayer of microlenses and a partially light transmissive mirror disposed behind the rear surfaces of at least some of said microlenses such that under retroreflective viewing conditions the sheet is brightly retroreflective in the areas occupied by the mirror, characterized in that there is an axial marking at the rear of at least some of the microlenses, which markings together are viewable as an image across a predetermined conical field in ordinary diffuse light conditions.
Claim 2
Dependent Claim
81 words
A substantially transparent sheet comprising a monolayer of microlenses and a partially light transmissive mirror disposed behind the rear surfaces of at least some of said microlenses such that under retroreflective viewing conditions the sheet is brightly retroreflective in the areas occupied by the mirror, characterized in that there is an axial marking at the rear of at least some of the microlenses, which markings together are viewable as an image across a predetermined conical field in ordinary diffuse light conditions.
Claim 3
Dependent Claim
81 words
A sheet as defined in claim 1, further characterized in that the microlenses and associated partially light transmissive mirror in a first, legend defining area have a different retroreflective efficiency than the microlenses and associated partially light transmissive mirror in a second, background defining area such that said sheet has retroreflective legend areas and retroreflective background areas, which areas are substantially indistinguishable under ordinary diffuse light viewing conditions, but which are readily visually dis- cemable from one another under retroreflective conditions.
Claim 4
Dependent Claim
85 words
A sheet comprising a monolayer of microspheres which partially protrude from the front of said sheet, characterized in that at least some of the microspheres having a marking in their embedded portion, which markings together are viewable across a predetermined conical field of view in ordinary diffuse light as an image, and a partially light transmissive mirror disposed behind the rear surfaces of some of the microspheres such that under retroreflective viewing conditions the sheeting is brightly retroreflective in the areas occupied by the mirror.
Claim 5
Dependent Claim
85 words
A sheet comprising a monolayer of microspheres which partially protrude from the front of said sheet, characterized in that at least some of the microspheres having a marking in their embedded portion, which markings together are viewable across a predetermined conical field of view in ordinary diffuse light as an image, and a partially light transmissive mirror disposed behind the rear surfaces of some of the microspheres such that under retroreflective viewing conditions the sheeting is brightly retroreflective in the areas occupied by the mirror.
Claim 6
Dependent Claim
79 words
A sheet as defined in claim 3, further characterized in that the microspheres and associated partially light transmissive mirror in a first, legend defining area have a different retroreflective efficiency than the microspheres and associated partially light transmissive mirror in a second, background defining area such that said sheet has retroreflective legend areas and retroreflective background areas, which areas are substantially indistinguishable under ordinary diffuse light viewing conditions, but which are readily discernable from one another under retroreflective c-nditions.
Claim 7
Dependent Claim
80 words
A substantially transparent sheet comprising a monolayer of microlenses, characterized in that there is an axial marking at the rear of at least some of the microlenses which markings together are viewable as an image from the front of the sheeting in ordinary diffuse light conditions, and under retroreflective conditions are viewable as a dark image across a predetermined conical field of view and are viewable as a bright image within a region annular to said conical field of view.
Claim 8
Dependent Claim
80 words
A substantially transparent sheet comprising a monolayer of microlenses, characterized in that there is an axial marking at the rear of at least some of the microlenses which markings together are viewable as an image from the front of the sheeting in ordinary diffuse light conditions, and under retroreflective conditions are viewable as a dark image across a predetermined conical field of view and are viewable as a bright image within a region annular to said conical field of view.
Claim 9
Dependent Claim
27 words
A sheet as defined in claim 5, further characterized in that the markings are viewable as an image across a wide angle under ordinary diffuse light conditions.
Claim 10
Dependent Claim
44 words
A substantially transparent sheet comprising a monolayer of microlenses, characterized in that there is a deformation at the rear of at least some of the microlenses, which deformations together are viewable as an image across a predetermined conical field in ordinary diffuse light conditions.
Claim 11
Dependent Claim
44 words
A substantially transparent sheet comprising a monolayer of microlenses, characterized in that there is a deformation at the rear of at least some of the microlenses, which deformations together are viewable as an image across a predetermined conical field in ordinary diffuse light conditions.
Claim 12
Dependent Claim
36 words
A sheet as defined in claim 7, further characterized in that there is a partially light transmissive mirror disposed behind at least some of the microlenses and wherein said deformations comprise a set of radial cracks.
Claim 13
Dependent Claim
79 words
A sheet as defined in claim 8, further characterized in that the microlenses and associated partially light transmissive mirror in a first, legend defining area have a different retroreflective efficiency than the microlenses and associated partially light transmissive mirror in a second, background defining area such that said sheet has retroreflective legend areas and retroreflective background areas, which areas are substantially indistinguishable under ordinary diffuse light viewing conditions, but are readily visually discernable from one another under retroreflective conditions.
Claim 14
Dependent Claim
60 words
A sheet as defined in claim 7, further characterized in that when said sheet is viewed under retroreflective lighting conditions within a predetermined conical field of view said deformations appear darker than surrounding background areas, and when viewed under retroreflective lighting conditions other than within said predetermined conical field of view said deformations appear brighter than said surrounding background areas.
Claim 15
Dependent Claim
109 words
A substantially transparent sheet comprising a monolayer of microlenses which partially protrude from the front of said sheet, characterized in that at least some of the microlenses have a deformation in their embedded portion, which deformations together are viewable across a predetermined conical field of view in ordinary diffuse light as an image, and each said deformation being such that when said sheet is viewed under retroreflective lighting conditions within a predetermined conical field of view said deformations appear darker than surrounding background areas and when viewed under retroreflective lighting conditions other than within said predetermined conical field of view said deformations appear brighter than said surrounding background areas.
Claim 16
Dependent Claim
109 words
A substantially transparent sheet comprising a monolayer of microlenses which partially protrude from the front of said sheet, characterized in that at least some of the microlenses have a deformation in their embedded portion, which deformations together are viewable across a predetermined conical field of view in ordinary diffuse light as an image, and each said deformation being such that when said sheet is viewed under retroreflective lighting conditions within a predetermined conical field of view said deformations appear darker than surrounding background areas and when viewed under retroreflective lighting conditions other than within said predetermined conical field of view said deformations appear brighter than said surrounding background areas.
Claim 17
Dependent Claim
24 words
A sheet as defined in any one of claims 1-11, further characterized in that the microlenses partially protrude from the front of the sheet.
Claim 18
Dependent Claim
18 words
A sheet as defined in any one of claims 1-12, further characterized in that said microlenses are glass.
Claim 19
Dependent Claim
18 words
A sheet as defined in any one of claims 1-13, further characterized in that said microlenses are microspheres.
Claim 20
Dependent Claim
20 words
A sheet as defined in claim 14, further characterized in that said microspheres have a refractive index of about 1.9.
Claim 21
Independent Claim
87 words
A method of forming directional images in substantially transparent sheeting comprising a monolayer of closely spaced microlenses and a partially light transmissive mirror disposed at the rear surfaces of at least some of said microlenses, characterized in that said method comprises directing a laser beam at a selected angle of incidence to the face of said sheeting, the wavelength of the laser being selected such that the beam is focused by the microlenses to form a marking at the rear of each microlens which said beam strikes.
Claim 22
Independent Claim
87 words
A method of forming directional images in substantially transparent sheeting comprising a monolayer of closely spaced microlenses and a partially light transmissive mirror disposed at the rear surfaces of at least some of said microlenses, characterized in that said method comprises directing a laser beam at a selected angle of incidence to the face of said sheeting, the wavelength of the laser being selected such that the beam is focused by the microlenses to form a marking at the rear of each microlens which said beam strikes.
Claim 23
Dependent Claim
61 words
A method as defined in claim 16, further characterized in that said laser beam has a wavelength of approximately 532 nanometers, a pulse duration of from approximately 200 to 400 nanoseconds, a pulse frequency of from approximately 2 to 10 kilohertz, and a power intensity at the surface of said sheeting of approximately from 0.01 to 10.0 megawatts per square centimeter.
Claim 24
Independent Claim
74 words
A method of forming directional images in substantially transparent sheeting comprising a monolayer of closely spaced microlenses, characterized in that said method comprises directing a laser beam with a short pulse duration at a selected angle of incidence to the face of said sheeting, the wavelength of the laser being selected such that the beam is focused by the microlenses to form a deformation at the rear of each microlens which said beam strikes.
Claim 25
Independent Claim
74 words
A method of forming directional images in substantially transparent sheeting comprising a monolayer of closely spaced microlenses, characterized in that said method comprises directing a laser beam with a short pulse duration at a selected angle of incidence to the face of said sheeting, the wavelength of the laser being selected such that the beam is focused by the microlenses to form a deformation at the rear of each microlens which said beam strikes.
Claim 26
Dependent Claim
37 words
A method as defined in claim 18, further characterized in that said substantially transparent sheeting is retroreflective and further comprises a partially light transmissive mirror disposed at the rear surfaces of at least some of said microlenses.
Claim 27
Independent Claim
18 words
A method as defined in any one of claims 16-19, further characterized in that said microlenses are glass.
Claim 28
Independent Claim
18 words
A method as defined in any one of claims 16-20, further characterized in that said microlenses are microspheres.
Claim 29
Dependent Claim
20 words
A method as defined in claim 21, further characterized in that said microspheres have a refractive index of about 1.9.
Claim 30
Independent Claim
49 words
A method as defined in any one of claims 16-22, further characterized in that said sheeting has been adhesively bonded over the information area of a document without appreciably interfering with the legibility of that information before said laser beam has been directed at the face of said sheeting.
Claim 31
Independent Claim
41 words
A method as defined in any one of claims 16-22, further characterized in that said method further comprises adapting said sheeting to be adhesively bonded over the information area of a document without appreciably interfering with the legibility of that information.
Claim 32
Independent Claim
64 words
A method as defined in any one of claims 16-24, further characterized in that said laser beam is selected to form deformations which can be viewed as an image under diffuse light conditions only across a cone which has a width of about 6 to 20 degrees, and wherein said angle of incidence is appreciably different from angles at which documents are normally viewed.
Claim 33
Independent Claim
57 words
A method as defined in any one of claims 16-25, further characterized in that said laser beam is directed at a second different selected angle of incidence to the face of said sheeting to form a second set of deformations, which set of deformations when viewed at said second selected angle of incidence appears as an image.
References Cited (Backward Citations)
No citation records indexed.
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