Directional image transmission sheet and method of making same
US5644431A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 13, 1994 |
| Grant date | Jul 1, 1997 |
| Priority date | — |
| Expiry date | Apr 13, 2014 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02E10/40
- WIPO fieldThermal processes and apparatus
- WIPO sectorMechanical engineering
Abstract
There is disclosed a partially transparent, directional viewing sheet formed of plastic material with lenses, preferably lenticular lenses, formed on both the front and the back surfaces of the sheet, there being on at least one of the surfaces intervening spaces between the lenses which spaces are not fully transparent and may be imprinted with an image that is viewable through the sheet from some directions. Preferably such lenses separated by non-transparent intervening spaces are concave lenses with a radius of curvature which is less than the radius of curvature of convex lenses, on the other surface, causing the concave lens focal length to be less than, typically about one-half of, the focal length of the convex lenses. The thickness of the sheet and hence the spacing between each concave lens and a corresponding convex lens causes the lenses axial spacing to be about the difference in focal lengths of the lenses producing the effect of a tiny Galilean telescope. The view through such a sheet in a direction substantially aligned with the optical axis of the tiny telescope is a minimally distorted view of objects distant from or near to the opposite side of the sheet while of…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.