Light Guide Structure with Quarter Wave Plate for Backlight Efficiency
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Solution Overview
Problem
Existing edge lighting type backlight modules suffer from significant light loss as they only allow linear polarized light to pass through, resulting in low light utilization efficiency.
Innovation Solution
A light guide structure comprising a light guide plate with a reflection type brightness enhancement film and a quarter wavelength plate, where the slow axis of the quarter wavelength plate is at a 45-degree angle to the transmission axis of the brightness enhancement film, and a reflection film, which cooperates to convert non-coincident light into linearly polarized light, reducing losses and increasing utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a reflection type brightness enhancement film is used in an edge lighting type backlight module, then the brightness enhancement effect is improved, but light loss increases because the film only allows linear polarized light to pass through
Solution Approach 1:
A quarter wavelength plate is introduced as an intermediary component between the light guide plate and the reflection type brightness enhancement film. This quarter wavelength plate converts the polarization state of light, enabling circularly polarized light to be transformed into linearly polarized light that can pass through the brightness enhancement film, thereby reducing light loss while maintaining brightness enhancement.
Solution Approach 2:
The invention changes the polarization state parameter of light by using a quarter wavelength plate. The plate transforms the polarization characteristics of incident light, converting non-linear polarized light into linearly polarized light, which matches the transmission requirements of the reflection type brightness enhancement film and reduces energy loss.
2Ease of operation
If a reflection type brightness enhancement film is used, then light direction control is improved, but light utilization efficiency deteriorates due to polarization mismatch
Solution Approach 1:
The quarter wavelength plate serves as a mediator that transforms the polarization state of light before it reaches the reflection type brightness enhancement film. This transformation ensures that the light can be properly controlled in direction while maintaining high utilization efficiency, resolving the contradiction between direction control and efficiency.
Solution Approach 2:
By changing the polarization parameter of light using the quarter wavelength plate, the system achieves both good light direction control and high utilization efficiency. The parameter transformation enables the light to match the requirements of the brightness enhancement film while minimizing loss.
3Device complexity
If a traditional edge lighting backlight module is used, then the structure is simple, but light loss is significant and light utilization rate is low
Solution Approach 1:
The quarter wavelength plate is added as an intermediary component to the traditional edge lighting backlight module. Although this increases structural complexity slightly, it dramatically reduces light loss by transforming polarization states, enabling the light to be effectively utilized by the reflection type brightness enhancement film.
Solution Approach 2:
The invention converts the potentially harmful effect of polarization mismatch (which causes light loss) into a beneficial outcome. By using the quarter wavelength plate to transform the polarization state, the previously wasted light energy is now effectively utilized, turning a disadvantage into an advantage.
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 described configuration effectively reduces light loss and enhances light utilization by converting exiting light into linearly polarized light that can pass through the brightness enhancement film, thereby improving the overall efficiency of the backlight module.
Implementation Method 1
a quarter wavelength plate, being disposed between the light-exiting surface of the light guide plate and the reflection type brightness enhancement film, with an angle of 45 degree existing between a slow axis of the quarter wavelength plate and a transmission axis of the reflection type brightness enhancement film
Implementation Method 2
a reflection type brightness enhancement film, being disposed at a side where the light-exiting surface of the light guide plate is located
Data Source
AI summary
A light guide structure (10), a backlight module (20) and a display device are disclosed, which can reduce loss of light in travelling and increase utilization rate of light. The light guide structure (10) including: a light guide plate (1) including a light-exiting surface (11) and a reflection surface (12) that are opposite to each other and a side surface (13) connecting the light-exiting surface (11) with the reflection surface (12), a material of the light guide plate (1) being an isotropic material; a reflection type brightness enhancement film (2) that is disposed at a side where the light-exiting surface (11) of the light guide plate (1) is located; a quarter wavelength plate (3) that is disposed between the light-exiting surface (11) of the light guide plate (1) and the reflection type brightness enhancement film (2), with an angle of 45 degree existing between a slow axis of the quarter wavelength plate (3) and a transmission axis of the reflection type brightness enhancement film (2); and a reflection film (4) that is disposed at a side where the reflection surface (12) of the light guide plate (1) is located.