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METHOD TO ENHANCE THE OPTICAL CHARACTERISTICS OF HOLOGRAPHIC FILMS

IP.com Disclosure Number: IPCOM000009124D
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-08
Document File: 2 page(s) / 126K

Publishing Venue

Motorola

Related People

Giovanni Jaramillo: AUTHOR

Abstract

Holographic films, or Hfilms, have been in use in many hand held products manufactured by Motorola. The Htilm when laminated to an LCD (liquid crystal display), improves the contrast and eliminates a major percentage of the glare that is visible in most products that do not use the Hfdm. The Hfilm is manufactured in the U.S. by Polaroid and DuPont. It is laminated to LCDs by several LCD manufacturers. Htilms when used in products with large displays have a greater chance to display cosmetic defects. These defects usually translate into higher production costs.

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8 MOTOROLA

Technical Developments

METHOD TO ENHANCE THE OPTICAL CHARACTERISTICS OF HOLOGRAPHIC FILMS

by Giovanni Jaramillo

BACKGROUND

  Holographic films, or Hfilms, have been in use in many hand held products manufactured by Motorola. The Htilm when laminated to an LCD (liquid crystal display), improves the contrast and eliminates a major percentage of the glare that is visible in most products that do not use the Hfdm. The Hfilm is manufactured in the U.S. by Polaroid and DuPont. It is laminated to LCDs by several LCD manufacturers. Htilms when used in products with large displays have a greater chance to display cosmetic defects. These defects usually translate into higher production costs.

PROBLEM AND IMPROVEMENTS

  During the early production of a new multiline display pager, there were a number of cosmetic defects observed relating to Htilm. Those defective LCDs or LCD display module assemblies had to be scrapped, and it will be appreciated, having to scrap the entire module leads to substantial scrap costs.

  In order to confront this problem, a new method for laminating the Hfilm was conceptualized and tested. The new method consists of removing the Hfilm from the LCD and transferring the lamination process to the front surface of an electrolumines- cent, or EL, panel. The EL panel is the device that provides backlighting to the LCD. This lamination process is quite effective as confirmed during tests and demonstrations of the process. The process eliminates not only LCD cosmetic defects, but is also expected to improve the optical characteristics of the Hfilm when backlighted. The change in process does not cause any significant changes to the optical characteristics of the Hfilm during ambi- ent light conditions, and the new process is actually more flexible when matching or making improve- ments to the optical characteristics of the Hfilm under ambient light conditions. The contrast, view-

ing angle, color and appearance of the LCD is in most cases subjective, and can vary from user to user. These characteristics can easily be modified or improved with the new lamination process described. The new lamination process allows changes to the size of the air gap between the Hfim and the rear polarizer, and allows the tilting of the Hfilm/El panel structure in relation to the LCD. Changing either the air gap and/or tilting the Hfllm/El panel structure allows control of the view- ing angle, or viewing cone, and the angle of the glare produced on the LCD in relation to the observ- er. With the new process, these two parameters may be customized for each product. The modular Hfilm/EL panel device may also be improved by the addition of filters positioned between the front of the Hfilm and the LCD. The...