Backlight Module Cavity Height Reduction via Lens and Inverse Prism
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Solution Overview
Problem
Typical direct-type backlight modules require a significant cavity height, making it difficult to reduce their thickness, and often result in lower brightness and dynamic range in display devices like LCDs.
Innovation Solution
Incorporating lens units with a concave inside surface and a convex outside surface to emit light beams at a predetermined angle, combined with an inverse prism sheet to guide these beams towards the display panel, reducing the cavity height and enhancing brightness and dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a typical direct-type backlight module is used, then the structure is simple and easy to manufacture, but the cavity height must be sufficiently large making it difficult to reduce thickness
Solution Approach 1:
The patent changes the optical parameters by introducing lens units with specific focal lengths and inverse prism sheets with predetermined angles to control light emission angles. This allows the cavity height to be reduced to 0.1mm or less while maintaining proper light guidance to the display panel, resolving the contradiction between reducing cavity height and maintaining manufacturability.
Solution Approach 2:
The patent introduces lens units and inverse prism sheets as intermediary optical elements between the light source and display panel. These intermediaries control and redirect light paths, enabling the system to function properly with a significantly reduced cavity height compared to typical direct-type backlight modules.
2Length of moving object
If the cavity height is reduced, then the thickness is reduced, but the brightness and dynamic range deteriorate
Solution Approach 1:
The patent optimizes optical parameters including the focal length of lens units, the angle of inverse prisms, and the distance between optical elements to maximize light extraction efficiency. By precisely controlling these parameters, the system achieves high brightness and dynamic range performance even with a cavity height of 0.1mm or less.
Solution Approach 2:
The patent applies different optical properties to different regions of the backlight module. The lens units have specific focal lengths optimized for their positions, and the inverse prism sheet has varying angles to control light distribution. This localized optimization ensures uniform high brightness across the display panel despite the reduced cavity height.
3Length of moving object
If the cavity height is reduced, then the thickness is reduced, but the light guidance capability deteriorates
Solution Approach 1:
The patent introduces inverse prism sheets as intermediary elements that actively guide and redirect light beams toward the display panel. These prisms with predetermined angles ensure that light from the reduced-cavity backlight module is properly directed, maintaining excellent light guidance capability despite the limited space.
Solution Approach 2:
The patent optimizes the angle parameters of the inverse prism sheet to match the emission characteristics of the lens units. By carefully selecting and adjusting these angular parameters, the system achieves effective light guidance and extraction efficiency even with the severely reduced cavity height of 0.1mm or less.
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 effectively reduces the cavity height of the backlight module while achieving high brightness and dynamic range by optimizing the emission and guidance of light beams, thereby improving the thinness and performance of the backlight module.
Implementation Method 1
each has a concave inside surface covering the corresponding light-emitting element and a convex outside surface covering the concave inside surface. Of at least a portion of the light beams emitted from the convex outside surface, each has a predetermined light-emitting angle θo
Implementation Method 2
The inverse prism sheet is disposed between the lens units and the display panel, and has a plurality of inverse prisms, each of the inverse prisms having a vertex corner. most of the light beams are guided to travel forward to a display panel by the inverse prism sheet
Data Source
AI summary
A display device including a display panel and a backlight module is provided. The backlight module is correspondingly disposed below the display panel and includes light-emitting elements providing light beams and disposed on a circuit board, lens units each being disposed on a corresponding light-emitting element and having a concave inside surface covering the corresponding light-emitting element and a convex outside surface covering the concave inside surface, and an inverse prism sheet disposed between the lens units and the display panel, and the inverse prism sheet having inverse prisms with a vertex corner. At least a portion of the light beams emitted from the convex outside surface each has a predetermined light-emitting angle θo larger than 30 degrees and less than 90 degrees. The backlight module has a height of cavity D being a distance between the vertex corner and the circuit board, and 10 μm≤D<30 mm.