Dual-Mode Pixel Cell for 2D and 3D Imaging
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Solution Overview
Problem
Conventional image sensors face challenges in achieving high spatial resolution and efficient power consumption when performing both 2D and 3D imaging, as they typically require separate pixel cells for each mode, leading to lower spatial resolution and increased form factor and power consumption, especially in wearable devices.
Innovation Solution
A dual-mode pixel cell that can operate in both 2D and 3D imaging modes using the same set of pixel cells, with configurable voltage sources to bias the photodiode for intensity measurement in 2D mode and time-of-flight measurement in 3D mode, allowing the same pixel cell array to generate both 2D and 3D images simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate pixel cells are used for 2D and 3D imaging, then each mode can be optimized independently, but spatial resolution decreases and form factor increases
Solution Approach 1:
The pixel cell is designed to perform multiple functions by switching between 2D imaging mode and 3D time-of-flight imaging mode using the same physical pixel cell array. The photodiode can be configured through voltage control to operate in different measurement modes, eliminating the need for separate pixel cell arrays for each function.
Solution Approach 2:
The patent combines 2D imaging functionality and 3D time-of-flight imaging functionality into a single integrated pixel cell structure. The same photodiode, transistor, and capacitor components serve both imaging modes, merging what would traditionally require separate hardware systems into one unified device.
2Measurement precision
If separate pixel cells are used for 2D and 3D imaging, then each mode can be optimized independently, but power consumption increases
Solution Approach 1:
The pixel cell is designed to perform multiple functions by switching between 2D imaging mode and 3D time-of-flight imaging mode using the same physical pixel cell array. The photodiode can be configured through voltage control to operate in different measurement modes, eliminating the need for separate pixel cell arrays for each function.
Solution Approach 2:
The patent combines 2D imaging functionality and 3D time-of-flight imaging functionality into a single integrated pixel cell structure. The same photodiode, transistor, and capacitor components serve both imaging modes, merging what would traditionally require separate hardware systems into one unified device.
3Measurement precision
If the photodiode is biased for high sensitivity in 3D mode, then time-of-flight measurement accuracy improves, but light intensity measurement range decreases
Solution Approach 1:
The bias voltage applied to the photodiode is made dynamic rather than fixed. The system can switch between different bias voltage levels depending on the operating mode: a first bias voltage for 2D imaging mode and a second bias voltage for 3D time-of-flight imaging mode. This dynamic reconfiguration allows the photodiode to optimize its characteristics for each specific measurement task.
Solution Approach 2:
The patent changes the electrical parameters (bias voltage) of the photodiode based on the required measurement mode. By adjusting the bias voltage parameter, the photodiode's sensitivity and operating characteristics are modified to suit either 2D intensity measurement or 3D time-of-flight measurement 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
This approach improves spatial resolution by utilizing the full potential of the pixel cell array while reducing the form factor and power consumption, enabling more accurate and efficient fusion of 2D and 3D image data for applications like VR/AR/MR.
Implementation Method 1
A typical image sensor includes a photodiode to sense incident light by converting photons into charges (e.g., electrons or holes)
Implementation Method 2
In the second mode, the one or more voltage sources are configured to bias the photodiode to generate an avalanche current upon receiving the first photon of the incident light
Data Source
AI summary
Examples of an image sensor are disclosed. In one example, the image sensor comprises a dual-mode pixel cell operable in a first mode and in a second mode at different times, the pixel cell including a photodiode to receive incident light. The image sensor further comprises one or more configurable voltage sources coupled with the photodiode. In the first mode, the one or more voltage sources are configured to bias the photodiode to generate a quantity of charges that reflects a quantity of photons of the incident light received by the photodiode within a first exposure period. In the second mode, the one or more voltage sources are configured to bias the photodiode to generate a signal corresponding to a time when the photodiode receives a first photon of the incident light within a second exposure period for a time-of-flight measurement.