Under-Display Light Sensor With Wavelength Conversion for Silicon Pixels
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Solution Overview
Problem
Existing light sensors, particularly proximity sensors, are disadvantaged when arranged under display screens lacking a notch, leading to undesirable phenomena like pixel activation and white spots due to light absorption by the display's silicon components.
Innovation Solution
A light sensor design that includes an optical device converting light at a first wavelength (1100-1600 nm) to a second wavelength (600-1000 nm) for reception by silicon photoconversion areas, using a laser source to emit light orthogonal to the display, and a protective housing to isolate components, preventing light absorption by the display's silicon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the light sensor is arranged under the display screen without a notch, then the display area is increased, but light absorption by silicon components causes pixel activation and white spots
Solution Approach 1:
An optical converter is introduced as an intermediary component between the infrared light source and the silicon-based pixel sensor. This converter receives infrared light at wavelengths between 1100 nm and 1600 nm and converts it to visible light wavelengths between 600 nm and 1000 nm, which can then be detected by the silicon photoconversion area without causing the harmful absorption effects that occur with direct infrared illumination
Solution Approach 2:
The optical converter changes the wavelength parameter of the light signal. By converting infrared light (1100-1600 nm) to visible light (600-1000 nm), the system operates in a wavelength range that avoids silicon absorption issues while maintaining sensor functionality, thus resolving the contradiction between increased display area and light absorption problems
2Reliability
If a laser source is used to emit light through the display, then proximity detection is enabled, but silicon absorption causes undesirable phenomena
Solution Approach 1:
The optical converter serves as a mediator that receives the laser-emitted infrared light and transforms it into visible light before it reaches the silicon photoconversion area. This intermediate conversion step enables proximity detection functionality while preventing the harmful effects of direct infrared light interaction with silicon components
Solution Approach 2:
The system replaces direct infrared detection with an optical conversion mechanism. Instead of using silicon to directly detect infrared light (which causes absorption problems), the system substitutes this with an optical converter that transforms the infrared signal into a visible light signal that silicon can detect without the same harmful absorption effects
3Ease of manufacture
If the optical device converts light wavelength, then silicon photoconversion can be used, but additional components increase device complexity
Solution Approach 1:
The optical converter is integrated with the pixel sensor in a combined structure where the converter is positioned directly above the photoconversion area within the same sensor assembly. This merging of functions reduces the overall device complexity compared to having separate infrared source, transmission path, and detection components
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 light absorption by the display's silicon, reducing undesirable phenomena and allowing for simpler, less expensive laser source implementation, while maintaining sensor functionality.
Implementation Method 1
the device being configured, when the first face receives light at a first wavelength between 1100 nm and 1600 nm, to convert the received light to light at a second wavelength between 600 nm and 1000 nm
Implementation Method 2
at least one pixel with a silicon photoconversion area arranged opposite the second face of the optical device
Data Source
AI summary
The present disclosure relates to a light sensor comprising: an optical device comprising a first face configured to receive light and a second face, the device being configured, when the first face receives the light at a first wavelength between 1100 nm and 1600 nm, to convert the received light to the light at a second wavelength between 600 nm and 1000 nm, and to emit the light at the second wavelength through the second face; and at least one pixel having a silicon photoconversion area arranged opposite the second face of the optical device.