Optical System With Layered Filtering for Blue and UV Blocking
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Solution Overview
Problem
Conventional backlight units emit harmful low wavelength blue light and ultraviolet light that can cause eye damage, and existing light absorbing dyes used to block these wavelengths often result in undesirable color shifts.
Innovation Solution
An optical system comprising an extended illumination source with a reflective polarizer and an optical filter, both made of multiple thin polymeric layers, designed to selectively reflect and transmit light based on polarization state, effectively blocking harmful blue light and UV while maintaining color balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If light absorbing dyes are used to block harmful blue light and UV, then viewer safety is improved, but color balance deteriorates due to undesirable color shifts
Solution Approach 1:
The optical system segments the filtering function into multiple thin polymeric layers (at least 10 layers) rather than using a single thick dye layer. Each layer contributes to the overall filtering effect, enabling precise control over which wavelengths are blocked while maintaining color balance.
Solution Approach 2:
The patent changes the physical parameters of the filtering structure by using multiple ultra-thin layers (each less than 300 nm thick) instead of conventional thick dye layers. This parameter change allows selective wavelength blocking without the broad absorption that causes color shifts.
2Object-affected harmful factors
If multiple thin polymeric layers are used in the reflective polarizer and optical filter, then harmful blue light and UV blocking is improved, but device complexity increases
Solution Approach 1:
The patent combines the reflective polarizer and optical filter into a single integrated structure where both functions are achieved through the same multiple thin polymeric layers. This merging reduces overall device complexity compared to having separate components.
Solution Approach 2:
The multiple thin polymeric layers serve multiple functions simultaneously: they act as both the reflective polarizer and the optical filter. This multi-functionality eliminates the need for separate components, reducing device complexity while maintaining effective harmful wavelength blocking.
3Ease of manufacture
If conventional thick polymeric layers are used, then manufacturing is simpler, but harmful blue light blocking effectiveness is reduced
Solution Approach 1:
The patent segments the polymeric filtering structure into multiple thin layers instead of using a single thick layer. This segmentation enables better control over light interaction, improving harmful blue light blocking effectiveness while maintaining manufacturability through standard deposition techniques.
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 system efficiently blocks harmful blue light and UV light without significant color shift, ensuring viewer safety and maintaining display quality.
Implementation Method 1
the plurality of first polymeric layers reflects greater than about 60% of the incident light having a first polarization state, and transmits greater than about 60% of the incident light having an orthogonal second polarization state
Implementation Method 2
the plurality of second polymeric layers transmits greater than about 70% of the incident light for green and red wavelengths, and transmits less than about 60% of incident light for smaller blue wavelengths
Data Source
AI summary
An optical system includes an extended illumination source configured to emit light from an extended emission surface thereof toward a display panel. The emitted light includes substantially distinct blue, green and red emission spectra having respective blue, green and red peaks at respective blue, green and red peak wavelengths, and corresponding blue, green and red full widths at half maxima (FWHMs). The blue FWHM extends from a smaller blue wavelength to a longer blue wavelength. The optical system further includes reflective polarizer disposed on the emission surface of the extended illumination source. The reflective polarizer includes a plurality of first polymeric layers. The optical system also includes an optical filter disposed between the reflective polarizer and the emission surface of the extended illumination source.