Time-of-Flight Sensor Readout Architecture for 3D Imaging
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Solution Overview
Problem
Conventional 3D image creation using stereo cameras is complex and requires significant processing power, making it difficult to achieve real-time 3D imaging, especially in small devices due to the need for minimum camera separation and high computational demands.
Innovation Solution
A time-of-flight sensor system that employs a light source, a pixel array with reconfigurable binning capabilities, and phase modulation to calculate object distance based on the round-trip time of light, enabling efficient 3D image capture with reduced computational requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If stereo cameras are used to create 3D images, then 3D imaging capability is achieved, but device complexity and processing power requirements increase significantly
Solution Approach 1:
The patent replaces the mechanical/optical stereo camera system with an electronic time-of-flight sensing system. Instead of using multiple physical cameras requiring spatial separation and complex triangulation algorithms, the invention uses a single sensor array that electronically measures flight time of photons to directly obtain depth information, dramatically simplifying the system architecture.
Solution Approach 2:
The patent changes the fundamental measurement parameter from optical triangulation (requiring baseline separation) to time-of-flight measurement. By measuring the time it takes for photons to travel to and from the object, the system directly obtains depth information without requiring complex geometric calculations or multiple cameras.
2Productivity
If stereo cameras are used for real-time 3D imaging, then 3D image acquisition is possible, but processing power requirements become prohibitive
Solution Approach 1:
The patent replaces computationally intensive triangulation algorithms with direct time-of-flight measurement. The depth information is obtained through physical measurement of light travel time rather than through complex image processing and mathematical triangulation, dramatically reducing computational requirements.
Solution Approach 2:
The time-of-flight sensor array performs depth measurement inherently through the physics of light propagation. Each pixel independently measures the time of flight for its corresponding scene point, performing the depth calculation automatically through the measurement process itself rather than requiring post-processing computation.
3Adaptability or versatility
If multiple cameras are separated by minimum distance for stereo imaging, then 3D triangulation is possible, but device size increases
Solution Approach 1:
The patent replaces the physical baseline separation requirement of stereo cameras with electronic time-of-flight measurement. A single sensor array can perform depth measurement without requiring any spatial separation between multiple cameras, enabling miniaturization of the device.
4Measurement precision
If conventional stereo triangulation is used, then 3D images can be created, but measurement precision and speed are insufficient for real-time applications
Solution Approach 1:
The patent changes the measurement approach from indirect optical triangulation to direct time-of-flight measurement. By measuring the actual time it takes for photons to travel to and from the object, the system obtains precise depth information directly through physical measurement rather than through computational triangulation.
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
Enables real-time 3D image capture with improved efficiency and reduced power consumption, suitable for small devices by leveraging indirect time-of-flight measurements and reconfigurable binning architectures within the time-of-flight pixel array.
Implementation Method 1
Each pixel circuit includes a photodiode configured to photogenerate charge in response to incident light
Implementation Method 2
Time-of-flight cameras typically employ a light source that directs light at an object, a sensor that detects the light that is reflected from the object, and a processing unit that calculates the distance to the object based on the round-trip time it takes for the light to travel to and from the object
Data Source
AI summary
A time-of-flight pixel array includes photodiodes that generate charge in response to incident reflected modulated light. First transfer transistors transfer a first portion of the charge from the photodiodes in response to a first modulation signal and second transfer transistors transfer a second portion of the charge from the photodiodes in response to a second modulation signal, which is an inverted first modulation signal. First floating diffusions are coupled to the first transfer transistors. A binning transistor is coupled between one of the first floating diffusions and another one of the first floating diffusions. A first memory node is coupled to one of the first floating diffusions through a first sample and hold transistor and a second memory node is coupled to another one of the first floating diffusions through a second sample and hold transistor.