Tilted Rolling Shutter Sensor Motion Compensation
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Solution Overview
Problem
Cameras struggle to capture clear images while in motion due to defocus blur, motion blur, and noise at low light levels, and typically focus on a shallow range of depths, making it difficult to recognize features like text in images.
Innovation Solution
An image capture system with a tilted image sensor and rotational oscillation about a vertical axis, where the image sensor is tilted with one edge closer to the lens to focus on distant objects, and a rolling-shutter image sensor with readout times progressing from back to front, providing time-varying image motion compensation to address motion blur and focus on a range of distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a camera captures images while in motion, then the ability to capture dynamic scenes is improved, but motion blur and defocus blur increase
Solution Approach 1:
The patent applies dynamics by making the image sensor tilt angle adjustable and time-varying. The sensor plane is tilted at an angle relative to the lens optical axis, and this tilt angle can be dynamically adjusted during image capture to compensate for motion-induced focus variations across the sensor surface, thereby reducing both motion blur and defocus blur simultaneously
Solution Approach 2:
The patent changes the geometric parameter of the sensor-lens configuration by tilting the sensor plane at a specific angle relative to the optical axis. This parameter change creates a mapping where different regions of the sensor correspond to different object distances, enabling the system to capture images of moving objects with reduced blur by optimizing focus for the dominant motion direction
2Adaptability or versatility
If the image sensor is tilted to focus on distant objects, then focus range is improved, but the shallow depth of focus limitation persists
Solution Approach 1:
The patent applies local quality by creating different focus characteristics for different regions of the image sensor. The tilted sensor plane ensures that different spatial regions of the sensor correspond to different object distances, with each region optimized for its specific distance range. This allows the system to capture objects at multiple distances with acceptable focus in a single image
Solution Approach 2:
The patent introduces an additional geometric dimension by tilting the sensor plane relative to the optical axis. This transforms the traditional parallel sensor-lens configuration into a tilted configuration, adding a spatial dimension to the focus mapping that enables extended depth coverage across the sensor surface
3Speed
If a rolling shutter readout is used, then readout speed is improved, but motion distortion increases
Solution Approach 1:
The patent combines rolling shutter readout with dynamic tilt angle adjustment, where the tilt angle is varied during the readout process to compensate for the temporal progression of the rolling shutter. This dynamic adjustment counteracts the motion-induced geometric distortion while maintaining the high readout speed advantage of rolling shutter operation
Data Source
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AI summary
An example image system (210) may include a lens (220) that produces an image, an image sensor (230), an image stabilizer, and a controller (310). This image sensor (230) has a first edge and an opposite second edge. The first edge is placed closer to lens (210) such that it focuses on more distant objects. The image stabilizer provides a time-varying compensation of image motion at the image sensor. The controller (310) operates the image capture system (210) in a repeating cycle where the sensor (230) exposes and reads out an image progressively from one edge to the opposite edge. The controller (310) operates the image stabilizer to provide an image motion compensation that varies in time such that the image motion compensation is greater when exposing and reading the second edge of the sensor (230) than when exposing and reading the first edge of the sensor (230).