Non-Avalanche Depth Sensor With Low-Latency Photodetection
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Solution Overview
Problem
Conventional 3D imagers and depth sensors face limitations due to high dark current, low quantum efficiency, and long read-out latency in solid-state light sensors, which hinder accurate depth measurement and sensitivity, especially in low-light conditions.
Innovation Solution
The development of low-latency, multi-photowell light sensors with pinned photodiodes and JFET-based devices that reduce read-out latency to sub-nanosecond levels, enabling rapid signal digitization and improved depth sensing through multi-carrier photowell depth and analog front-end/time-to-digital converter combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If avalanche photodetectors are used to improve sensitivity, then detection sensitivity is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent replaces expensive, complex avalanche photodetectors with simpler, non-avalanche photodetectors that have sufficient lifetime for the application. This substitution reduces device complexity and manufacturing difficulty while maintaining adequate detection sensitivity through alternative design optimizations.
Solution Approach 2:
The patent changes the operating parameters and design specifications of the photodetector, specifically using non-avalanche photodetectors with photocharge storage capacity of more than one electron. This parameter change achieves the required sensitivity without the complexity of avalanche multiplication mechanisms.
2Device complexity
If non-avalanche photodetectors are used to reduce complexity, then device complexity is reduced, but detection sensitivity deteriorates
Solution Approach 1:
The patent implements preliminary action by pre-charging the photodetector with a photocharge storage capacity of more than one electron before detection. This preliminary charging compensates for the lower gain of non-avalanche photodetectors, enabling them to achieve sufficient detection sensitivity without the complexity of avalanche multiplication.
Solution Approach 2:
The patent uses a simplified photodetector design that copies only the essential detection function without the complex avalanche multiplication mechanism. This simplified copy achieves adequate performance for the intended application while significantly reducing device complexity.
3Measurement precision
If high photocharge storage capacity is used to improve sensitivity, then detection sensitivity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies partial action by providing the photodetector with a photocharge storage capacity that is more than one electron but not excessively high. This moderate level of photocharge storage achieves the required detection sensitivity while avoiding the stringent manufacturing precision requirements that would be needed for extremely high photocharge storage capacities.
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 significantly enhances depth sensing accuracy and sensitivity by reducing readout latency by two orders of magnitude, allowing for higher resolution and finer depth measurements compared to conventional avalanche-gain sensors.
Implementation Method 1
a photodetector (115) having a photocharge storage capacity in excess of one electron
Data Source
Figure 1~4
Figure 5~11
AI summary
A sensing device (100) includes a light source (101) to emit light, a light sensor (105) to detect reflection of the emitted light and distance determination circuitry responsive to reflected-light detection within the light sensor. The light sensor includes a photodetector (115) having a photocharge storage capacity in excess of one electron and an output circuit (117) that generates an output signal responsive to light detection within the photodetector with sub-hundred nanosecond latency. A distance determination circuitry (119) measures an elapsed time based on transition of the output signal in response to photonic detection within the photodetector and determines, based on the elapsed time, a distance between the sensing device and a surface that yielded the reflection of the emitted light.