Single Camera Depth Sensing via Segmented Photodiodes
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Solution Overview
Problem
Existing methods for capturing 3D images using a single camera, such as stereo cameras, time-of-flight, and structure light, face challenges like requiring large device modifications, complex optical systems, and potential eye injury from projected laser light, making them unsuitable for smartphones.
Innovation Solution
The use of sensing pixels with microlenses and multiple photodiodes in a single camera system, where the microlens covers pairs or arrays of photodiodes to detect phase differences and determine depth information without the need for additional optical components or complex masks, allowing for precise 3D reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stereo camera is used to capture 3D images, then depth information can be obtained, but device size and complexity increase due to requiring sufficient parallax and relatively large base line between two cameras
Solution Approach 1:
The invention segments each pixel into multiple sub-pixels (first and second photoelectric conversion units) within the same pixel location. This segmentation allows depth information to be obtained by comparing light intensity between sub-pixels, eliminating the need for multiple separate cameras while maintaining depth measurement capability.
Solution Approach 2:
The invention transitions from a two-camera spatial arrangement to a multi-layer photoelectric conversion structure within a single camera. By stacking multiple photoelectric conversion units at different depths or positions within each pixel, the system achieves depth measurement without increasing the overall device footprint.
2Measurement precision
If time-of-flight solution is used to capture 3D images, then depth information can be obtained, but advanced electronic processor is needed to determine extremely short time difference
Solution Approach 1:
The invention replaces the time-based measurement approach with an intensity-based comparison approach. Instead of measuring the time of flight of light, the system compares light intensity between different photoelectric conversion units within each pixel, significantly reducing computational requirements while maintaining depth measurement accuracy.
3Measurement precision
If structure light solution is used to capture 3D images, then depth information can be obtained, but relatively more complex optical system is needed for projecting structure light
Solution Approach 1:
The invention extracts the depth measurement function from complex external optical projection systems and integrates it directly into the camera sensor itself. By using multiple photoelectric conversion units within each pixel to compare light intensity, the system eliminates the need for separate structure light projection components.
4Measurement precision
If structure light with VCSELs is used to capture 3D images, then depth information can be obtained, but device size increases making it unsuitable for smartphones
Solution Approach 1:
The invention merges the depth measurement function with the standard camera imaging function by integrating multiple photoelectric conversion units within each pixel of the same sensor array. This combination allows the single camera to perform both 2D imaging and 3D depth measurement simultaneously without requiring separate VCSEL projection systems or additional camera modules.
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 efficient and precise 3D image capture without increasing device size or complexity, improving signal-to-noise ratio and allowing for auto focus capabilities within a smartphone form factor.
Implementation Method 1
sensing pixels each comprising a microlens and multiple photodiodes under the microlens
Implementation Method 2
multiple photodiodes under the microlens
Data Source
AI summary
An optical system comprises an imaging lens for imaging an object to an image and a sensing pixel array for detecting lights from the object toward the image. The sensing pixel array comprises a first sensing pixel and a second sensing pixel, each sensing pixel comprising a microlens covering a one-dimensional series of photodiodes having n photodiodes. A photodiode at an end of the one-dimensional series of photodiodes of the first sensing pixel detects a first light from the object toward the image, and a photodiode at an opposite end of the one-dimensional series of photodiodes of the second sensing pixel detects a second light from the object toward the image, where the first light and the second light pass opposite parts of the imaging lens.