LCD with diffuser having diffusing particles therein located between polarizers

• US 5,949,506 A
• Filed: 11/24/1998
• Issued: 09/07/1999
• Est. Priority Date: 04/01/1998
• Status: Expired due to Fees

• Current Assignee: InnoLux Corporation
• Original Assignee: OIS Optical Imaging Systems, Inc. (KOCH Industries Incorporated)
• Inventors: VanderPloeg, John A., Jones, Michael R., Warmuth, Matthew W., Lovshe, Laurie D.
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): DUDEK, JAMES A
• Application Number:
  US09/199,048
• Time in Patent Office: 287 Days
• Field of Search: 349/187, 349/112
• US Class Current: 349/112
• CPC Class Codes: G02F 1/133504 Diffusing, scattering, diffracting elements associated to illuminating devices G02F1/133606
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G02F 1/133516 Methods for their manufacture, e.g. printing, electro-deposition or photolithography
• CPC Class Codes: G02F 1/133565 inside the LC elements, i.e. between the cell substrates

Abstract

A liquid crystal display includes a patternable diffusing layer therein positioned between the display'"'"'s substrates. The diffusing (or diffuser) layer includes a host material having a plurality of particles (e.g. substantially transparent spherical balls or spacers) provided therein in order to perform a diffusion function. The refractive index n_p of the particles is different (i.e. Δn) from the refractive index n_h of the host material by at least about 0.05, and Δn is preferably from about 0.05-0.15. In certain embodiments, photoimageable color filters, with diffusing particles embedded therein, function as discrete diffusing members across the passive substrate. In other embodiments, a substantially continuous diffusing layer with a transparent host, including spherical balls embedded therein, may be provided across the passive substrate between the substrate and the color filters. Still further, the diffusing layer with transparent host material may be provided between the common electrode and black matrix members on the passive substrate.

Claims

1. A method of making a liquid crystal display, the method comprising the steps of:

providing first and second substantially transparent substrates;

providing first and second polarizers;

spin coating a diffusing material onto the second substrate, said diffusing material including a host material which is substantially transparent to at least one wavelength of visible light and a plurality of diffusing particles embedded therein;

sandwiching a liquid crystal layer between the first and second substrates so that the diffusing material is located at a point between the second substrate and the liquid crystal layer whereby the diffusing material is positioned between the substrates; and

locating the first and second polarizers so that the resulting display includes the first and second substrates both located between the first and second polarizers.

2. The method of claim 1, further comprising the step of photo-imaging the diffusing material using ultraviolet radiation so as to form a diffusing layer.

3. The method of claim 2, further comprising the step of photo-imaging the diffusing material using ultraviolet radiation so as to form an array of discrete diffusing portions which make up the diffusing layer.

4. The method of claim 1, wherein the recited steps are performed in the order in which they are recited.

5. The method of claim 1, wherein the host material has a refractive index at least about 0.05 less than a refractive index of the particles, and wherein the particles are substantially transparent to all visible wavelengths of light and wherein the particles are substantially spherical in shape.