Proximity Sensor Wavelength Shift Eliminates OLED Bright Spots
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Solution Overview
Problem
Conventional proximity sensors disposed under OLED panels emit infrared light that causes visible light generation, leading to bright spots on the panel, which can be mistaken for panel defects.
Innovation Solution
A proximity sensing device with an emitting module that emits invisible light with a peak wavelength of 1000 nm to 1580 nm, preventing visible light generation on the OLED panel, comprising semiconductor chips, light converting structures with fluorescent materials, and light absorbing or filtering layers to ensure only invisible light is emitted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional proximity sensor emits infrared light to detect proximity, then proximity sensing function is achieved, but visible light is generated causing bright spots on the OLED panel
Solution Approach 1:
The patent changes the wavelength parameter of the emitted light from conventional infrared (780nm-940nm) to a longer wavelength range (1000nm-1580nm). This parameter change allows the light to penetrate the OLED panel without being absorbed by the semiconductor layer, thereby preventing photoluminescence and bright spot generation while maintaining proximity sensing capability
Solution Approach 2:
Instead of trying to block or filter the visible light generated by the semiconductor layer, the patent inverts the approach by selecting an emission wavelength that naturally avoids the problematic absorption band of the OLED materials. The emitting module is designed to emit light in the 1000nm-1580nm range where the OLED panel is transparent, thus the light passes through without generating visible photoluminescence
2Object-affected harmful factors
If the peak wavelength of emitted light is increased to prevent visible light generation, then bright spot generation is prevented, but penetration capability may be reduced
Solution Approach 1:
The patent identifies and exploits a specific wavelength window (1000nm-1580nm) where the OLED panel materials exhibit high transmission characteristics. By changing the emission wavelength to this optimal range, the patent simultaneously achieves both objectives: preventing visible light generation (by avoiding absorption bands) and maintaining penetration capability (by selecting a transmission window)
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
Prevents the generation of bright spots on OLED panels while maintaining effective penetration for proximity sensing, enhancing user experience by avoiding false defect perceptions and maintaining screen clarity.
Implementation Method 1
The emitting module is configured to emit an invisible light which has a peak wavelength not less than 1000 nm
Implementation Method 2
the infrared light emitted therefrom will make a semiconductor layer of the OLED panel to generate a visible light (photoluminescence)
Implementation Method 3
The light converting structure is disposed on the semiconductor chip and comprises an adhesive (glue) and a fluorescent material, and the fluorescent material is disposed in the adhesive to convert the visible light into the invisible light
Implementation Method 4
the light absorbing layer is disposed on the light converting structure to absorb the visible light
Implementation Method 5
The receiving module is disposed adjacent to the emitting module and configured to receive a reflected light of the invisible light
Data Source
AI summary
A proximity sensing device which is disposed under the OLED panel and has an emitting module and a receiving module, is provided. The emitting module can emit an invisible light which has a peak wavelength not less than 1000 nm. The receiving module is disposed adjacent to the emitting module and can receive a reflecting light from the reflected invisible light. Therefore, the invisible light passing through the OLED panel will not cause a bright spot on the panel.