US 8408778

Here's a concise summary of US patent 8408778:

US Patent 8408778 Summary

• Title: Light source and display device having the same
• Assignee: The current assignee is Light Guide Innovations LLC. The original assignee was LG Innotek Co Ltd.
• Inventor: Hyung Hwa Park
• Filing Date: 2010-02-02
• Issue Date: 2013-04-02
• Abstract: A display device is provided, featuring a light unit that includes a light guide plate, a light emitting module with multiple light-emitting diodes (LEDs) that shine light onto the light guide plate, and a color coordinate conversion sheet. This conversion sheet is placed on the light guide plate and serves to adjust the color output of the light emitted by the light emitting module to fall within a specific target color distribution range.

Plain-Language Overview of Independent Claims:

• Independent Claim 1: This claim describes a light source for a display. It includes a light guide plate, at least one light emitting module (containing multiple LEDs that direct light into the side of the light guide plate), and an optical sheet placed on top of the light guide plate. The optical sheet consists of a diffusion sheet and a prism sheet. Crucially, a conversion sheet is situated on top of this optical sheet. This conversion sheet modifies the color of the light emitted by the LED module to a desired target color after the light has passed through both the diffusion and prism sheets.
• Independent Claim 20: This claim defines a display device. It comprises a cover, a light emitting module (with multiple LEDs) located on the cover, and a light guide plate positioned alongside the light emitting module. An optical sheet (which includes a diffusion sheet and a prism sheet) is placed on the light guide plate, and a display panel sits on top of the optical sheet. A conversion layer is inserted between the optical sheet and the display panel. This conversion layer's function is to change the initial color of the light coming from the light guide plate to a target color, specifically converting the light's color after it has passed through the diffusion and prism sheets.
• Independent Claim 23: This claim outlines another light source. It includes a light guide plate, at least one light emitting module (with multiple LEDs) that emits light onto a side edge of the light guide plate, and an optical sheet that sits on the top surface of the light guide plate. This optical sheet is composed of a diffusion sheet with a prism sheet on top of it. A conversion sheet is provided on the top surface of the optical sheet, converting the color of light from the LED module to a target color. Additionally, a reflective plate is positioned underneath the light guide plate. A key feature of this claim is that the conversion sheet is coated with a color coordinate material on the upper surface of the diffusion sheet, specifically converting the color of the light after it has been diffused by the diffusion sheet.

Litigation:
The patent family for US8408778 has litigation activity. This includes a US case filed in the Texas Eastern District Court [cite: https://patents.google.com/patent/US8408778/en] and a PTAB case, IPR2025-01526, which was filed but procedurally not instituted [cite: https://patents.google.com/patent/US8408778/en]. The CAFC 2026 dockets searched did not return results specific to US8408778.