Direct Backlight Light Guide Plate for Thin HDR Displays
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Solution Overview
Problem
Liquid crystal displays with edge type backlights struggle to achieve high dynamic range imaging due to limitations in luminance uniformity across the screen, and existing direct type backlight solutions with lenses face challenges in reducing thickness and improving light uniformity.
Innovation Solution
A display apparatus employing a direct type backlight with regularly arranged light emitting diode packages, each coupled with a reflector and a lens having a concave light incident face, and an optical part including a phosphor sheet and optical sheet, which spreads light laterally to enhance uniformity without the need for a separate lens, thus minimizing thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a lens is used in a direct type backlight unit to spread light laterally, then luminance uniformity is improved, but the thickness of the display apparatus increases
Solution Approach 1:
The patent extracts and eliminates the lens component from the backlight unit, replacing its light-spreading function with a light guide plate that has a specifically designed upper surface. This removal of the lens directly reduces the thickness of the display apparatus while maintaining the necessary light distribution functionality through alternative means.
Solution Approach 2:
The patent changes the surface parameters of the light guide plate by forming microlens arrays, prism patterns, or roughness structures on its upper surface. These parameter changes enable the light guide plate to perform light redirection and spreading functions that previously required a separate lens, thereby achieving uniform luminance without increasing thickness.
2Length of stationary object
If an edge type backlight unit is used to reduce thickness, then the thickness of the display apparatus is reduced, but HDR imaging capability is lost
Solution Approach 1:
The patent merges the light source arrangement of a direct type backlight (multiple LEDs across the display area) with the thin-profile structure of an edge type backlight. By positioning multiple light emitting diodes along the edge and using a light guide plate to distribute their light across the display surface, the system achieves both thinness and the luminance control needed for HDR imaging.
Solution Approach 2:
The patent transitions from a single-edge light source configuration to a multi-point light source configuration distributed along the edge. This dimensional change in light source arrangement, combined with the light guide plate's light redistribution capability, enables HDR imaging functionality while maintaining the thin profile characteristic of edge-type backlights.
3Illumination intensity
If a lens is used to spread light from LEDs, then light distribution is improved, but device complexity increases
Solution Approach 1:
The patent combines the light spreading function into the light guide plate itself by forming optical structures (microlens arrays, prism patterns, or roughness) directly on its upper surface. This integration eliminates the need for a separate lens component, reducing device complexity while maintaining effective light distribution across the display area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves improved light uniformity and high dynamic range imaging while minimizing the display's thickness by using lenses with concave portions to direct light emission and a reflector to enhance lateral light distribution, overcoming previous limitations in luminance uniformity and thickness reduction.
Implementation Method 1
a light guide plate disposed to cover the plurality of light emitting diodes and spreading light emitted from the plurality of light emitting diodes
Implementation Method 2
The light guide plate is formed with light source grooves placed corresponding to locations of the plurality of light emitting diodes, respectively, such that light emitted from each of the light emitting diodes enters the corresponding light source groove
Data Source
Figure 1a
Figure 1b~2a
Figure 2b
AI summary
A display apparatus and a backlight unit thereof are disclosed. The display apparatus includes: a frame; a plurality of light emitting diodes regularly arranged on the frame; an optical part disposed above the plurality of light emitting diodes and including a display panel and at least one of a phosphor sheet and an optical sheet; and a light guide plate disposed between the frame and the optical part to cover the plurality of light emitting diodes, wherein the light guide plate is formed with light source grooves placed corresponding to locations of the plurality of light emitting diodes, respectively, such that light emitted from each of the light emitting diodes enters the corresponding light source groove. The light guide plate of the backlight unit includes a light source groove placed corresponding to a location of a light emitting diode package so as to spread light in a lateral direction when the light enters the light guide plate, thereby enabling use of a direct type backlight unit without a separate lens.