Global Shutter Image Sensor for 3D TOF Depth Mapping
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Solution Overview
Problem
Existing time-of-flight image sensors are complex and larger than regular image sensors, requiring specialized design and layout, which complicates the pixel structure and increases power consumption.
Innovation Solution
An image sensor with global shutter pixels that can operate in both imaging and time-of-flight modes, using subsets of pixels with different phases and interpolation techniques to generate depth information, allowing for a less complex pixel structure and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated time-of-flight pixels with specialized design are used, then time-of-flight measurement capability is improved, but device complexity and pixel size increase
Solution Approach 1:
The patent applies universality by enabling regular image sensor pixels to perform both standard imaging and time-of-flight measurement functions. The same pixel array is used for both purposes by switching between different operating modes, eliminating the need for separate dedicated TOF pixels and their associated complex structures.
Solution Approach 2:
The patent utilizes parameter changes by modifying the operational parameters of existing pixels rather than changing their physical structure. By adjusting timing sequences, gate control signals, and readout modes, the pixels can switch between imaging and TOF measurement modes, achieving TOF capability without increasing device complexity.
2Measurement precision
If dedicated time-of-flight pixels with specialized design are used, then time-of-flight measurement capability is improved, but power consumption increases
Solution Approach 1:
The same pixel array serves dual purposes for both imaging and time-of-flight measurements, eliminating the need for separate dedicated TOF pixel circuits that would consume additional power. The universal pixel design reduces overall power consumption while maintaining TOF measurement capability.
Solution Approach 2:
Power consumption is reduced by changing operational parameters of existing pixels rather than activating additional dedicated TOF pixel structures. The patent uses timing-based differentiation and gate control to enable TOF mode in standard pixels, avoiding the continuous power demand of specialized TOF hardware.
3Measurement precision
If separate dedicated image sensor and time-of-flight sensor are used, then imaging quality and depth measurement are improved, but device complexity and cost increase
Solution Approach 1:
The patent merges imaging and time-of-flight measurement functions into a single integrated sensor array. By combining these functions in one device rather than using separate sensors, the system reduces hardware complexity, alignment requirements, and overall system cost while maintaining both imaging quality and depth measurement capabilities.
Solution Approach 2:
A single pixel array is designed to perform multiple functions - both standard color imaging and time-of-flight depth measurement. This multi-functional approach eliminates the need for separate dedicated sensors, reducing device complexity and integration requirements while achieving both imaging objectives.
4Device complexity
If regular image sensor pixels are used for time-of-flight measurement, then device complexity is reduced, but measurement precision may be compromised
Solution Approach 1:
The patent employs periodic modulation of the light source and corresponding periodic gating of the pixel readout to enable time-of-flight measurement. By using phase-modulated light pulses and synchronized periodic sampling, the system achieves accurate depth measurement with standard pixels, compensating for their lack of specialized TOF optimization.
Solution Approach 2:
The patent replaces the need for specialized mechanical or structural TOF pixel components with electronic timing and signal processing. By substituting hardware complexity with sophisticated timing sequences and phase detection algorithms, the system achieves TOF measurement precision using simpler regular pixel structures.
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 cost-effective 3D imaging with high resolution and lower power consumption, facilitating faster autofocus and accurate depth mapping without the need for additional hardware modifications.
Implementation Method 1
depth information is determined by measuring a travel time of a light pulse emitted by a light source arranged close to the sensor. The time until the detection of the reflected light pulse by the image sensor is proportional to the distance of the reflecting object.
Implementation Method 2
Eventually light is reflected by any of the objects and traverses back to the time-of-flight camera
Implementation Method 3
an arrival time of a light pulse is measured by a photodetector such as a SPAD and the time is converted to a signal
Data Source
Figure 1
Figure 2a~2d
Figure 3
AI summary
An image sensor arrangement for determining a three-dimensional image comprises an image sensor (IS) comprising an array of global shutter pixels and a control unit (CTRL) which is configured to drive the image sensor in an imaging mode (IM) and in a time-of-flight mode (TM). In the imaging mode (IM), the control unit (CTRL) drives the pixels according to an imaging timing sequence. In the time-of-flight mode (TM), the control unit (CTRL) drives the pixels according to a time-of-flight, TOF, timing sequence. At least a first subset of pixels are operated with a phase delay with respect to at least a second subset of pixels according to a first phase and a second phase (Ø1, Ø2), respectively.