Image Sensor Dual-Direction Scanning Reduces Propagation Delay
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Solution Overview
Problem
Existing image sensors suffer from propagation delay issues due to fixed directional pixel selection, which becomes exacerbated as pixel size decreases and the number of pixels increases, leading to data distortion and loss, especially when using a single readout circuit offset to one side.
Innovation Solution
The imaging device employs a dual-direction scanning mechanism using multiple selection and readout circuits to scan a pixel array in both directions, enabling the merging of frame data from different directions to reduce propagation delay and attenuate fixed pattern noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single readout circuit is used with fixed directional pixel selection, then device complexity is reduced, but propagation delay increases and data distortion occurs
Solution Approach 1:
The pixel array is divided into multiple regions with different scanning directions. First and second selection circuits scan in opposite directions (e.g., first column to last column, and last column to first column respectively), creating segmented data paths that reduce propagation delay by distributing the scanning load across multiple directional paths.
Solution Approach 2:
The patent introduces a temporal dimension by alternately enabling different selection circuits in different time periods. During a first time period, the first selection circuit is enabled; during a second time period, the second selection circuit is enabled. This time-based dimension allows the system to achieve reduced propagation delay without requiring all circuits to operate simultaneously, thus managing complexity.
2Loss of time
If multiple selection circuits scanning in different directions are used, then propagation delay is reduced, but device complexity increases
Solution Approach 1:
Frame data from multiple scanning directions are merged by the image signal processor to generate a single output frame. The first and second readout circuits both read from the same pixel array but in different directions, and their data streams are combined, allowing the system to benefit from multiple paths while consolidating the final output to manage complexity.
Solution Approach 2:
The selection circuits are enabled periodically in alternating time periods rather than continuously. During the first time period, the first selection circuit operates; during the second time period, the second selection circuit operates. This periodic activation reduces the instantaneous complexity while maintaining the benefits of multi-directional scanning over time.
3Manufacturing precision
If pixel size is decreased and number of pixels is increased, then image resolution is improved, but propagation delay effect is exacerbated
Solution Approach 1:
By segmenting the pixel array into multiple scanning regions with opposite-direction selection circuits, the patent reduces the effective scanning distance for each circuit. Even with high pixel density, each selection circuit only needs to traverse a portion of the array, reducing propagation delay while maintaining high resolution through the increased total number of pixels.
Data Source
AI summary
An imaging device, image sensor and method are provided. A first scanning operation is performed on a pixel array in a first direction by a first selection circuit to generate first frame data by first readout circuit. A second scanning operation is performed on the pixel array in a second direction different from the first direction to generate second frame data by a second selection circuit. The first and second frame data are merged into single frame data by an image signal processor.