Low Profile Side Emitting LED With Integrated Optical Element
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Solution Overview
Problem
Existing illumination systems using side-emitting LEDs face challenges in efficiently directing light to the back surface of LCDs while maintaining uniform brightness, particularly in thin and battery-operated devices like cell phones and cameras, where traditional optical elements are too thick and obstructive.
Innovation Solution
A low-profile side-emitting LED design with optical elements such as collimating lenses or reflectors optically coupled to the LED's sidewalls, where the bottom edge of the optical element is positioned below the LED's sidewall, allowing for efficient collimation and redirection of light without obstruction, and using a molded lead frame to integrate the lens with the LED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional optical elements are used to direct light from side-emitting LEDs, then light directionality is improved, but the vertical height increases and the device becomes too thick
Solution Approach 1:
The patent transitions from traditional vertical stacking of optical elements to a horizontal integration approach where the optical element is positioned at the side of the LED. This dimensional reconfiguration allows light to be directed efficiently while maintaining a low vertical profile, resolving the contradiction between light directionality and device thickness.
Solution Approach 2:
The optical element is integrated within the LED package structure, with the LED chip mounted on a substrate that incorporates the optical element. This nested arrangement allows the optical component to be embedded within the existing device footprint rather than adding external bulk, thereby directing light effectively without increasing vertical height.
2Loss of energy
If optical elements are positioned to direct light efficiently, then illumination efficiency is improved, but the device complexity increases
Solution Approach 1:
The patent combines the LED chip, substrate, and optical element into a single integrated assembly. The optical element is incorporated directly into the mounting structure of the LED, eliminating the need for separate mounting brackets or additional alignment mechanisms. This merging of components maintains efficient light direction while reducing overall device complexity.
Solution Approach 2:
The substrate serves multiple functions: it provides mechanical support for the LED chip, acts as a mounting platform for the optical element, and facilitates thermal management. This multi-functionality reduces the need for additional specialized components, thereby improving illumination efficiency without proportionally increasing device complexity.
3Reliability
If the optical element bottom edge is positioned at or below the LED sidewall, then light coupling is improved, but manufacturing precision requirements increase
Solution Approach 1:
The optical element is pre-positioned and secured to the substrate before the LED chip is mounted. This preliminary positioning establishes a fixed reference framework that guides subsequent LED placement, ensuring the optical element's bottom edge is correctly positioned relative to the LED sidewall. This sequential assembly approach improves light coupling while managing manufacturing precision requirements through staged positioning.
Solution Approach 2:
The substrate acts as an intermediary component that mediates the positioning relationship between the LED chip and the optical element. By providing a common mounting platform with predefined alignment features, the substrate simplifies the positioning task and reduces the direct precision requirements between the LED and optical element, thereby improving light coupling without excessively increasing manufacturing difficulty.
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
This design enables thinner, more efficient, and uniformly illuminated backlighting systems with improved light coupling and reduced vertical height, enhancing the brightness and efficiency of displays and cameras.
Implementation Method 1
The lens associated with the light emitting sidewalls is used to collimate the side emitted light in the horizontal plane
Implementation Method 2
a reflective layer overlying the active layer and light emitting sidewalls between the active layer and the reflector layer
Data Source
Figure 1~3B
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Figure 6~8
AI summary
A low profile, side-emitting LED with one or more optical elements, such as a reflector or lens, optically coupled to each light emitting sidewall is described. In one embodiment, a reflector (62) is used to redirect the light emitted from each sidewall to a forward direction, e.g., in a flash configuration. In another embodiment, a lens (70) is used to collimate the side emitted light in the horizontal plane, e.g., for backlighting. Each entrance surface of the lens is positioned so that the bottom edge is at or below the bottom of the light emitting sidewall so that the base of the lens does not block light that is emitted by the LED.