MicroLED ToF Architecture With CMOS Integration for Low-Cost Depth Sensing
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Solution Overview
Problem
Existing optical time of flight (ToF) systems are costly and complex due to the use of VCSELs and SPADs, which have complex structures, low yields, and are not compatible with CMOS processes, making them unsuitable for low-cost applications like proximity sensors.
Innovation Solution
Utilizing microLEDs as light sources and CMOS-compatible detectors, integrated monolithically with silicon ToF circuitry, to create a low-cost, high-resolution ToF system with improved signal-to-noise ratio and high yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If VCSELs are used for depth mapping, then measurement precision is improved, but device complexity and cost increase due to requirement for precise angular alignment and temperature control
Solution Approach 1:
The patent replaces expensive, temperature-sensitive VCSELs with inexpensive, temperature-insensitive LEDs. The LEDs are considered 'short-living' in the sense that they don't require long-term stability through temperature control, but rather simple replacement or recalibration, eliminating the need for complex thermal management systems.
Solution Approach 2:
The patent extracts and removes the temperature control and precise alignment systems from the depth mapping apparatus. By using LEDs that are inherently insensitive to temperature variations and easier to align, the complex subsystems for maintaining VCSEL performance are eliminated entirely.
2Measurement precision
If VCSELs with precise angular alignment are used, then depth mapping accuracy is improved, but ease of manufacture deteriorates
Solution Approach 1:
The patent adopts inexpensive LEDs that can be manufactured and assembled without precision alignment equipment. The LEDs are designed to be easily replaceable or repositionable, making the manufacturing process simpler and more scalable compared to VCSELs that require specialized alignment fixtures and procedures.
Solution Approach 2:
The patent changes the key parameter from precise angular alignment to broader acceptance angles. LEDs naturally emit light in a wider angular range, which eliminates the need for sub-degree alignment precision during manufacturing, thereby simplifying the assembly process while maintaining adequate depth mapping performance.
3Adaptability or versatility
If multiple VCSELs are used for different wavelengths, then versatility is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses a single LED type that can operate across multiple wavelengths or be easily replaced with different LED types for different wavelength requirements. This universal approach allows the same basic hardware platform to serve multiple depth mapping applications without requiring separate, precisely aligned VCSEL assemblies for each wavelength.
Solution Approach 2:
The patent combines multiple wavelength capabilities into a single LED-based system rather than using separate VCSEL assemblies for each wavelength. This merging eliminates the need for multiple independent alignment systems and reduces overall device complexity while maintaining versatility across different wavelength requirements.
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
The system achieves high signal-to-noise characteristics and low manufacturing costs, enabling high-resolution depth mapping with scalable power and efficient use of microLED arrays for various applications.
Implementation Method 1
a plurality of microleds arranged in an array configuration, each microled of the plurality of microleds configured to emit light in response to application of a drive current
Data Source
Figure 1
Figure 2A~2B
Figure 3A
AI summary
A time of flight system may include one or more microLEDs and a photodetector monolithically integrated with integrated circuitry of the time of flight system. The microLEDs may be doped to provide increased speed of operation.