Backlight Module Polarization Recycling for LCD Light Loss
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Solution Overview
Problem
Conventional backlight modules using white LEDs in LCDs suffer from low photon utilization due to significant light loss through polarizers, resulting in reduced lightness.
Innovation Solution
A backlight module design incorporating a reflector base, phosphor layer, and optical film that reflects S-polarized light to excite phosphors, generating additional red and green light, which mixes with blue light to form white light, thereby increasing photon utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polarizer is used in the backlight module, then the LCD can achieve proper light transmission and display function, but 50% of the incident light is lost
Solution Approach 1:
The patent segments the light transmission path by introducing an optical film that selectively handles different polarizations. The optical film divides the incident light into P-polarized and S-polarized components, allowing P-polarized light to pass through while reflecting S-polarized light to excite phosphors, thus segmenting the function of light transmission and phosphor excitation.
Solution Approach 2:
The patent changes the polarization state parameter of light by using an optical film with specific optical properties. The optical film is designed to have different transmittance for different polarizations (P-polarized light passes through, S-polarized light is reflected), thereby changing how light interacts with subsequent components and reducing overall energy loss.
2Ease of manufacture
If a color filter is used in the LCD, then color display is achieved, but another 60% of the remaining incident light is lost
Solution Approach 1:
The patent performs preliminary action by generating red and green photons through phosphor excitation before the light reaches the color filter. By pre-generating the required color photons through phosphor conversion of reflected S-polarized light, the system reduces the burden on the color filter and improves overall light utilization efficiency.
3Illumination intensity
If a white LED is used as backlight source, then small size and high luminance are achieved, but photon utilization ratio is only about 45%
Solution Approach 1:
The patent introduces an optical film as an intermediary component between the white LED and the phosphor layer. This optical film mediates the interaction by reflecting S-polarized light to the phosphor layer while allowing P-polarized light to pass through, enabling more efficient photon utilization without changing the LED itself.
Solution Approach 2:
The patent implements self-service by using the reflected S-polarized light to excite phosphors that generate red and green photons, which then mix with the transmitted blue light to form white light. The system uses its own emitted light (S-polarized portion) to generate additional useful photons, creating a self-sustaining light generation cycle that improves overall efficiency.
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 increases photon utilization by up to 65%, enhancing the overall lightness of the LCD by optimizing the reflection and transmission of polarized light through the optical film.
Implementation Method 1
the optical film is disposed above the reflector base, the phosphor layer and the LED components for allowing P-polarized light of the first light beam to pass through the optical film and reflecting S-polarized light of the first light beam to the phosphor layer
Implementation Method 2
reflecting S-polarized light of the first light beam to the phosphor layer, thereby exciting the phosphor layer to generate a second light beam
Implementation Method 3
When the blue LED chip emits blue light, the blue light will excite the green and red phosphors contained in the encapsulant to generate red light and green light
Implementation Method 4
a white LED is formed by using a blue LED chip with an encapsulant containing green and red phosphors, wherein the encapsulant encapsulates the blue LED chip in a reflector base
Data Source
AI summary
A backlight module and a liquid crystal display are disclosed. In the backlight module having a reflector base, a phosphor layer is disposed on the reflector base, and a plurality of blue light emitting diode (LEDs) are disposed above the reflector base and the phosphor layer for emitting a first light beam. An optical film is disposed above the reflector base, the phosphor layer and the blue LEDs for allowing P-polarized light of the first light beam to pass therethrough and reflecting S-polarized light of the first light beam to the phosphor layer so as to excite the phosphor layer to generate a second light beam of which the wavelengths are different from those of the first light beam. After being reflected to the optical film by the reflector base, the second light beam transmits through the optical film, and mixes with the first light beam to generate white light.