Imageable prismatic array

• US 4,497,860 A
• Filed: 12/18/1978
• Issued: 02/05/1985
• Est. Priority Date: 12/18/1978
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Brady, Harold E. Jr.
• Primary Examiner(s): Silverman, Stanley S.
• Application Number:
  US05/970,548
• Time in Patent Office: 2,241 Days
• Field of Search: 96/1.1, 428/156, 428/913, 428/918, 340/146.3 P, 346/77 E, 346/134, 346/136, 365/124, 365/125, 430/12, 430/946, 350/167, 353/120, 353/122, 353/DIG. 5
• US Class Current: 428/156
• CPC Class Codes: G02B 27/4277 being separated by an air space
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• CPC Class Codes: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence
• CPC Class Codes: G03B 21/132 Overhead projectors, i.e. capable of projecting hand-writing or drawing during action epidiascopic projectors G03B21/08
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10S 428/918 Material abnormally transparent
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

Articles having on one surface thereof a linear prism array and a diffraction grating on the opposite surface are provided which are suitable for the preparation of projection transparencies.

Claims

1. An article suitable for the preparation of projection transparencies capable of providing a projected image based on non-diffused refraction of light comprising a sheet of transparent thermoplastic material having molded on one side thereof a linear prism array having sufficient molding stresses locked therein to exhibit a variation of at least 0.2 between the maximum and minimum optical density viewed through two polarized sheets with their axes of polarization perpendicular to each other wherein a linear prism array is on one side of the sheet and a diffraction grating is on the other side.

2. Projection transparencies comprising the article of claim 1 having areas of the diffraction grating deformed in accordance with a pattern.

3. An article suitable for the preparation of projection transparencies capable of providing a projected image based on non-diffused refraction of light comprising a sheet of transparent thermoplastic material having molded on one side thereof a linear prism array having sufficient molding stresses locked therein to exhibit a variation of at least 0.2 between the maximum and minimum optical density viewed through two polarized sheets with their axes of polarization perpendicular to each other said article having a second sheet juxtaposed in parallel therewith, the second sheet being a transparent sheet having a linear prism array thereon, the prism arrays of both sheets so arranged that light entering one sheet perpendicular to the plane of the sheet will exit the second sheet perpendicularly to the plane of the second sheet.

4. The article of claim 3 having a diffraction grating on the opposite side of said sheet.

5. The article of claim 3 in which the prisms are parallel and in which the faces of adjacent prisms in the linear prism array form an angle between them.

6. The article of claim 3 having a second linear prism array on the opposite side of said sheet.

7. An article suitable for the preparation of projection transparencies comprising a sheet of transparent thermoplastic material having on one face thereof a linear prism array and on the other face thereof a diffraction grating.

8. An article suitable for the preparation of projection transparencies capable of providing a projected image based on non-diffused refraction of light comprising a sheet of transparent thermoplastic material having molded on one side thereof a linear prism array having sufficient molding stresses locked therein to exhibit a variation of at least 0.2 between the maximum and minimum optical density viewed through two polarized sheets with their axes of polarization perpendicular to each other wherein a linear prism array is on both sides of the sheet.

9. An article suitable for the preparation of projection transparencies capable of providing a projected image based on non-diffused refraction of light comprising a sheet of transparent thermoplastic material having molded on one side thereof a linear prism array having sufficient molding stresses locked therein to exhibit a variation of at least 0.2 between the maximum and minimum:

optical density viewed through two polarized sheets with their axes of polarization perpendicular to each other said article having a second sheet juxtaposed in parallel therewith, the second sheet being a transparent sheet having a diffraction grating thereon.