Backlight Lens and Reflector for Uniform LED Illumination
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Solution Overview
Problem
In edge light type backlights, irregularities in luminance and chromaticity occur when LEDs are closely disposed with a light guide plate, leading to issues like the 'bulb shape' phenomenon, especially at the incidence part of the light guide plate, even with small LED intervals.
Innovation Solution
A backlight device design incorporating a light emitting element, a lens with converging and diverging surfaces, and a reflective member that reflects light from the lens' outgoing surface towards the light guide plate's incidence plane, enhancing light collection and distribution for uniform surface emission and reducing luminance irregularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If LEDs are disposed substantially in close contact with a light guide plate to reduce backlight thickness, then the backlight thickness is reduced, but irregularities in luminance and chromaticity occur at the incidence part of the light guide plate
Solution Approach 1:
A lens is introduced as an intermediary component between the LED and the light guide plate. The lens receives light from the LED and redirects it toward the light guide plate, preventing direct contact between the LED and the light guide plate while still achieving thin backlight design. This intermediary structure eliminates the bulb shape phenomenon and luminance irregularities that occur when LEDs are in direct contact with the light guide plate.
Solution Approach 2:
The patent uses a simple, cost-effective lens structure that can be easily manufactured and integrated into the backlight assembly. The lens serves its purpose of redirecting light without requiring complex mechanisms, making it a practical solution for mass-produced thin backlights while maintaining luminance uniformity.
2Device complexity
If LEDs are disposed in close contact with a light guide plate, then the structure is simplified, but chromaticity irregularities and bulb shape phenomenon are generated
Solution Approach 1:
The lens acts as a mediator that simplifies the overall structure by providing a straightforward optical path control mechanism. Instead of requiring complex LED positioning systems or multiple light guide plates, a single lens component achieves chromaticity uniformity by properly directing light from each LED to the light guide plate, thereby reducing structural complexity while improving chromaticity consistency.
3Illumination intensity
If the interval of LEDs is reduced to increase light emission density, then luminance is enhanced, but irregularities in luminance distribution become more pronounced
Solution Approach 1:
The patent divides the light emission function into multiple segments by using multiple LEDs with individual lenses. Each LED-lens combination acts as an independent light source unit that contributes to the overall luminance. By segmenting the light emission and controlling each segment with its own lens, the system achieves high luminance through reduced LED intervals while maintaining uniform luminance distribution across the light guide plate.
4Loss of energy
If a reflective member is added to reflect light toward the light guide plate, then light utilization efficiency is improved, but device complexity increases
Solution Approach 1:
The lens serves multiple functions: it redirects light toward the light guide plate, controls the angular distribution of light, and eliminates the bulb shape phenomenon. By making the lens multi-functional, the patent reduces the need for additional components like separate reflective members, thereby improving light utilization efficiency without significantly increasing device complexity.
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 increases the amount of light introduced into the light guide plate, achieving uniform light emission, enhanced luminance, and suppressed irregularities in luminance and chromaticity, while also simplifying the structure and reducing the size or thickness of the backlight device.
Implementation Method 1
a lens having an incident surface on which light emitted by the light emitting element is incident, and an outgoing surface which has an ability to converge the light
Implementation Method 2
a reflective member operative to reflect a portion of the light going out from the outgoing surface of the lens, toward the incidence plane of the light guide plate
Implementation Method 3
a light guide plate having a light incidence plane and introducing through the incidence plane the light going out from the outgoing surface, so as to perform surface light emission
Data Source
AI summary
Disclosed herein is a backlight device. The device includes: a light emitting element; a lens having an incident surface on which light emitted by the light emitting element is incident, and an outgoing surface which has an ability to converge the light and from which the light incident on the incident surface goes out; a light guide plate having a light incidence plane and introducing through the incidence plane the light going out from the outgoing surface, so as to perform surface light emission; and a reflective member operative to reflect a portion of the light going out from the outgoing surface of the lens, toward the incidence plane of the light guide plate.