Method and Apparatus for Preparing Gradient Polarization Sheet

摘要

A method and apparatus for continuously forming a web having a gradient polarization characteristic for use in sunglasses or other optical applications includes drawing a vertically oriented web of molecularly oriented material through a dye bath at an angle to the bath such that the residency time in the bath varies from top to bottom of the web to establish a polarization gradient from 100% at the top of the web to close to 0% at the bottom of the web. This process also creates a minimum transmissivity at the top of the web and a maximum transmissivity at the bottom of the web for permitting viewing displays using sunglasses having lenses cut from the web by viewing a display through the bottom portion of the sunglass lenses.

主权项

1. A method for preparing a gradient polarized sheet comprising the steps of:
providing a web of molecularly oriented material having a relatively small transverse dimension and top and bottom substantially parallel longitudinal edges; conducting the web into a bath of dye that has molecules that associate with the molecularly oriented molecules in the web to give the web a polarization characteristic such that the transverse plane through the longitudinal dimension of the web makes substantially a right angle with the plane of the surface of the dye bath, with the bottom longitudinal edge of the web entering the dye bath at an acute angle to the surface of the dye bath so that the web is at least partially progressively immersed in the dye bath; and, drawing the web through the dye bath so as to conduct the web through the dye bath and out of the dye bath to impart a transverse dye density gradient and thus a transverse polarization gradient to the deposited dye that is a function of the residence time of various portions of the web in the dye bath, thereby to establish a gradient polarization characteristic for the sheet.