Optical Sensor Transmittance via Refractive Index Matching
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Solution Overview
Problem
In electronic devices with extended displays, optical sensors mounted below the display panel face reduced transmittance due to reflections at the interfaces of the display panel layers, leading to increased power consumption to compensate for lower light sensitivity.
Innovation Solution
The implementation of a light-transmissive member with a refractive index matching the substrates, anti-reflection coating layers, and strategically placed openings in the polarization and optically clear adhesive layers reduces reflections and enhances light transmittance to the optical sensor, thereby decreasing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an optical sensor is disposed below the display panel to extend the display area, then the display area is extended and more information can be provided, but the transmittance of light to the sensor is reduced due to reflections at the interfaces of the display panel layers
Solution Approach 1:
An anti-reflection coating layer is introduced as an intermediary between the display panel layers and the optical sensor. This coating layer has a refractive index that is the geometric mean of the adjacent layers, creating a gradual transition in refractive indices that minimizes reflection at the interfaces and maximizes light transmission to the sensor.
Solution Approach 2:
The refractive index of the anti-reflection coating layer is specifically designed to be the geometric mean of the refractive indices of the adjacent display panel layers. By optimizing this parameter (refractive index), the coating achieves minimum reflection and maximum transmission of light to the optical sensor.
2Device complexity
If the transmittance of the sensor is lowered due to reflections, then the sensor can be mounted below the display panel, but the power consumption of the sensor increases to compensate for lower light sensitivity
Solution Approach 1:
The anti-reflection coating layer acts as a mediator that improves light transmission to the sensor, thereby reducing the sensor's power consumption. By minimizing reflections at the interfaces, more light reaches the sensor without requiring additional power compensation.
3Adaptability or versatility
If multiple layers are added above the optical sensor to form the display panel, then the display functionality is enhanced, but the number of interfaces increases and reflection losses accumulate
Solution Approach 1:
The anti-reflection coating layer is introduced as an intermediary between each pair of adjacent layers in the display panel stack. This coating minimizes reflection at each interface, preventing cumulative energy loss as light passes through multiple layers to reach the optical sensor.
Solution Approach 2:
By optimizing the refractive index parameter of the anti-reflection coating to be the geometric mean of adjacent layers, the system achieves minimum reflection at each interface, thereby minimizing total energy loss across multiple layers while maintaining full display functionality.
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 increases the transmittance of light to the optical sensor, reducing power consumption and improving its sensitivity by minimizing reflections at the display panel interfaces.
Implementation Method 1
a light-transmissive member (470) comprising a light-transmissive material disposed in at least a portion of the opening, the light-transmissive member having a second reflective index corresponding to the first reflective index of the second substrate
Implementation Method 2
anti-reflection coating layers, and strategically placed openings in the polarization and optically clear adhesive layers reduces reflections and enhances light transmittance
Data Source
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AI summary
Disclosed is an electronic device. An electronic device according to various embodiments may include an optical sensor and a display panel. The display panel may include a first substrate, a second substrate, a pixel layer disposed between the first substrate and the second substrate, the pixel layer having at least one opening in at least a portion thereof, and a light-transmissive member comprising a light-transmissive material disposed in at least a portion of the opening and having a second reflective index corresponding to a first reflective index of the second substrate. The optical sensor may be disposed below the second substrate and at least partially overlap a predetermined area of the display panel corresponding to the opening.