Ambient Light Sensor Wavelength Discrimination via Depth Segmentation
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Solution Overview
Problem
Ambient light sensors can only detect light intensity, not wavelength, which limits their ability to accurately identify light sources, and existing methods for wavelength detection are costly and inefficient.
Innovation Solution
The use of unshielded photo-detector pairs with different depths and optical filters allows for wavelength detection without additional optical filters, enabling accurate identification of light sources by computing the ratio of photo-currents generated by each detector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple photo-detectors with different optical filters are used to detect wavelength, then wavelength detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the wavelength detection function by using multiple photo-detectors at different depths within a single semiconductor structure. Each depth level detects different wavelength ranges, eliminating the need for separate optical filters on each detector. This segmentation approach maintains wavelength discrimination capability while reducing overall device complexity.
Solution Approach 2:
The patent makes the semiconductor structure universal by integrating multiple photo-detector layers that can detect different wavelengths simultaneously. The single semiconductor substrate serves multiple functions: it houses photo-detectors for various wavelength ranges (visible, near-infrared, short-wave infrared) and provides integrated readout circuits, replacing the need for separate filter-based systems.
2Measurement precision
If optical filters are interposed on photo-detectors to enable wavelength detection, then wavelength discrimination is improved, but light loss increases
Solution Approach 1:
The patent replaces the mechanical/optical filter system with an electronic detection system. Instead of using physical optical filters that absorb and block certain wavelengths (causing light loss), the invention uses photo-detectors at different depths that selectively detect different wavelength ranges through their inherent spectral response characteristics. This substitution eliminates light loss while maintaining wavelength discrimination.
Solution Approach 2:
The patent changes the detection parameter from optical filtering (which loses light) to depth-based photo-detector selection. By varying the depth of photo-detectors in the semiconductor structure, the system achieves wavelength-selective detection without blocking light paths. This parameter change from optical to structural depth enables wavelength discrimination with minimal light loss.
3Loss of energy
If simple photo-detectors without filters are used, then light transmission is improved, but wavelength detection capability deteriorates
Solution Approach 1:
The patent adds the depth dimension to the photo-detector structure to achieve wavelength discrimination. Instead of filtering light in the optical path (2D plane), the invention uses different depths (3D spatial dimension) within the semiconductor to create wavelength-selective detection. This dimensional approach allows full light transmission while maintaining wavelength detection capability through the depth-dependent spectral response of each photo-detector layer.
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 approach enhances the cost-effectiveness and precision of wavelength detection, improving the ability to identify light sources and reducing light loss, making it suitable for applications like ambient light sensing and camera technology.
Implementation Method 1
Both the first and second photo-detectors may be configured to detect light intensity of the incident light
Implementation Method 2
by using several photo-detectors each covered by different filters such a red, green blue, cyan, magenta, yellow, and infrared filters
Data Source
AI summary
In one embodiment, an ambient light sensor with first and second photo-detectors is disclosed. The first and second photo-detectors may have different depths and respond differently to light having a specific wavelength. The ambient lights sensor may further comprise a circuit configured to detect light of a specific wavelength. In another embodiment, the first and second photo-detectors may be configured such that each of the first and second photo-detectors detects coupling current from each other. In yet another embodiment, in addition to the first and second photo-detectors, a third photo-detector may be formed proximate to at least one of the first and second photo-detectors such that coupling photo-current is detected therein by the at least one of the first and second photo-detectors.