Geiger Mode Avalanche Photodiode Array Proximity Sensor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High precision proximity sensors using Geiger Mode Avalanche Photodiodes (GMAPs) are complex and expensive, making them unsuitable for commercial applications, as they require separate illumination and detection units and complex electronics.
Innovation Solution
A monolithic proximity sensor architecture where an array of Geiger mode avalanche photodiodes operates both as illumination and detection units, utilizing the increase in dark current or rate of current spikes to estimate object distance, with common anode and cathode contacts and integrated circuitry to sense these changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate illumination and detection units are used with complex electronics, then measurement precision is improved, but device complexity increases and manufacturing cost increases
Solution Approach 1:
The patent merges the illumination function and detection function into a single integrated sensor unit. The Geiger mode avalanche photodiode array simultaneously serves as both the light source (through electroluminescence in the depletion region) and the detector, eliminating the need for separate illumination units and complex control electronics while maintaining measurement precision
Solution Approach 2:
The Geiger mode avalanche photodiode array is designed to perform multiple functions: it detects photons from reflected light, generates illumination through electroluminescence in the depletion region, and provides timing reference signals. This multi-functionality reduces device complexity while preserving measurement capabilities
2Measurement precision
If separate illumination and detection units with complex electronics are used, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
By combining illumination and detection functions into a single photodiode array, the patent reduces the number of components that need to be manufactured and assembled, thereby lowering manufacturing costs while maintaining precision through the inherent capabilities of the Geiger mode operation
Solution Approach 2:
The patent operates the photodiodes in Geiger mode (above breakdown voltage) where dark current and electroluminescence parameters are exploited for both illumination and detection functions, enabling a simpler, more cost-effective design that maintains measurement precision through parameter optimization rather than complex hardware
3Device complexity
If dark current increase is used as the sensing mechanism, then device complexity is reduced, but measurement precision may be affected by dark current noise
Solution Approach 1:
The patent uses timing-based feedback mechanisms where the precise timing of current spikes (both from reflected photons and dark current events) is measured relative to a reference timing signal. This timing feedback allows the system to distinguish true reflection events from dark current noise while maintaining simple device architecture
Solution Approach 2:
The sensor operates with periodic illumination pulses and measures reflections within specific time windows. By synchronizing detection with periodic illumination cycles and using timing discrimination, the system can differentiate between signal photons and dark current events, maintaining precision despite using dark current as part of the sensing mechanism
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 simplifies the sensor design, reduces costs, and allows for precise distance measurements in high dark environments by leveraging the single photon sensitivity of GMAPs, enabling effective operation without separate illumination and detection units.
Implementation Method 1
GMAPs are semiconductor junction diodes reverse-biased a few volts above the breakdown voltage. At this operating condition, the electric field within a GMAP depletion layer is so high that a single carrier injected in this region triggers a self-sustaining avalanche multiplication process.
Implementation Method 2
They have many advantages in terms of excellent single photon response, high gain at low bias voltage, high detection efficiency in the visible range
Implementation Method 3
a single carrier injected in this region triggers a self-sustaining avalanche multiplication process. As a result, a sharp current pulse of a few mA and with a sub-nanosecond rise time is produced
Data Source
AI summary
A proximity sensor may include an array of Geiger mode avalanche photodiodes, each including an anode contact and a cathode contact. A common cathode contact may be coupled to the cathode contacts of the array to define a first connection lead at a back side of the array. A common anode collecting grid contact may be coupled to the anode contacts of the array to define a second connection lead of the array. Circuitry may be coupled with the first and second connection leads and configured to sense at least one of a dark current and a rate of current spikes generated in dark conditions, and generate an output signal representing an estimated distance of an object from the array upon the sensing.