Notch Filtering Materials for LED Display Contrast
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Solution Overview
Problem
Conventional LED displays suffer from significant reflection of ambient light, which impairs image visibility and requires increased power and thermal dissipation to maintain brightness, leading to reduced contrast and efficiency.
Innovation Solution
The use of notch filtering materials, such as rare earth materials and color pigments, is implemented in a light path between solid state light emitters and the light output surface to create spectral notches that attenuate ambient light without significantly affecting the emitted light, thereby reducing reflection and enhancing contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional LED packages with transparent encapsulants and reflector cups are used, then light extraction efficiency is maximized, but ambient light reflection significantly impairs display contrast
Solution Approach 1:
The patent applies different optical properties to different regions of the LED package. The encapsulant maintains high transparency for emitted light wavelengths, while the reflector cup applies a spectral notch filter that selectively attenuates ambient light wavelengths. This local differentiation of optical properties allows simultaneous optimization of light extraction and reflection reduction.
Solution Approach 2:
The patent changes the optical parameters of the reflector cup by incorporating a spectral notch filter that selectively attenuates specific wavelength ranges corresponding to ambient light. This parameter modification allows the reflector to maintain its light-reflecting function for emitted light while simultaneously reducing ambient light reflection, resolving the contrast impairment issue.
2Object-affected harmful factors
If neutral gray filters are positioned between reflector and light output surface to reduce ambient light reflection, then contrast is improved, but direct emitted light is attenuated requiring increased power and thermal dissipation
Solution Approach 1:
The patent changes the spectral selectivity parameter of the filtering mechanism. Instead of using a neutral gray filter that uniformly attenuates all wavelengths, the invention employs a spectral notch filter that selectively attenuates only the wavelength ranges corresponding to ambient light while transmitting the emitted light wavelengths with minimal loss. This parameter change enables contrast improvement without significant power penalty.
Solution Approach 2:
The patent applies wavelength-specific filtering properties to the reflector cup, creating a spectrally selective surface that differentiates between emitted light and ambient light. This local quality differentiation allows the system to reject ambient light reflection while preserving direct emitted light, avoiding the need for increased power consumption.
3Object-affected harmful factors
If neutral gray filters are used to attenuate reflected ambient light, then contrast is enhanced, but output of direct emitted light is reduced
Solution Approach 1:
The patent modifies the spectral transmission parameters of the filtering element by implementing a spectral notch filter with selective wavelength attenuation. This parameter change enables the filter to transmit direct emitted light with minimal attenuation while strongly attenuating reflected ambient light, thereby enhancing contrast without significantly reducing emitted light output.
Solution Approach 2:
The patent converts the harmful effect of ambient light reflection into a beneficial selective filtering mechanism. By designing the reflector cup with spectral notch filtering capability, the system selectively reflects emitted light while absorbing or attenuating ambient light wavelengths, transforming the problematic reflection into a useful wavelength-discrimination function.
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 solution effectively minimizes ambient light reflection, maintaining high brightness and contrast while reducing power consumption and thermal dissipation requirements compared to conventional neutral gray filtering methods.
Implementation Method 1
notch filtering materials, such as rare earth materials and color pigments, is implemented in a light path between solid state light emitters and the light output surface to create spectral notches that attenuate ambient light
Data Source
AI summary
Solid state light emitting devices and display devices include at least one filtering material arranged to provide at least one spectral notch comprising a wavelength of greatest attenuation in at least one spectrum between dominant wavelengths of solid state light emitters of the light emitting and/or display devices. The at least one spectral notch may be non-overlapping with a majority or an entirety of spectral output of each solid state light emitter. Filtering material may be arranged in a light path between at least some emitters and) at least one light output surface of a light emitting or display device, with the filtering material(s) arranged to receive incident ambient light, such that at least a portion of reflected ambient light exiting the device exhibits at least one spectral notch.