Digital Pixel Image Sensor Shared Transmission Lines
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Solution Overview
Problem
Current image sensors face challenges in efficiently converting optical images into electrical signals with high performance, particularly in terms of area, time, and power consumption, especially when storing and processing digital data at a pixel level.
Innovation Solution
The image sensor incorporates digital pixels with a photodetector, comparator, and memory cells that utilize a ramp signal for comparison and counting, allowing for the storage and output of digital data through shared transmission lines, reducing the need for extensive area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If digital pixels with memory cells are used to store detection signals, then data storage capability is improved, but pixel area increases
Solution Approach 1:
Multiple memory cells share common transmission lines for data output, merging the readout paths of multiple pixels. This allows several memory cells to utilize the same transmission infrastructure, reducing the total area required for transmission lines and enabling more efficient space utilization within the pixel array.
Solution Approach 2:
The transmission lines serve multiple functions: they are shared by multiple memory cells for data output and can be selectively activated based on reading requirements. This multi-functional approach allows the same physical infrastructure to support multiple storage and readout operations, improving area efficiency.
2Measurement precision
If multiple memory cells are added to store multiple counting values, then data storage precision is improved, but device complexity increases
Solution Approach 1:
Multiple memory cells are combined with shared transmission lines and control logic, reducing the overall complexity compared to having separate dedicated readout paths for each memory cell. The merging of resources allows precise multi-level data storage while maintaining manageable device complexity through resource sharing.
Solution Approach 2:
The data storage is segmented into multiple memory cells that can independently store different counting values (reset and signal levels), enabling precise multi-level data representation. This segmentation allows complex data to be broken down into manageable discrete storage units that can be controlled and read out systematically.
3Area of stationary object
If shared transmission lines are used for data output, then area consumption is reduced, but data reading speed decreases
Solution Approach 1:
Data reading from multiple memory cells occurs in periodic cycles, with control signals enabling sequential or time-multiplexed access to different memory cells through the shared transmission lines. This periodic action allows efficient utilization of shared resources while maintaining acceptable data reading throughput by organizing access patterns to minimize conflicts and maximize bandwidth utilization.
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 enhances the efficiency of image sensor operations by improving data storage, reading, and processing at the pixel level, leading to better performance in terms of area, time, and power usage, while also reducing noise and coupling issues compared to analog pixels.
Implementation Method 1
a photodetector that includes a photoelectric conversion element that outputs a detection signal in response to light incident thereon
Data Source
AI summary
An image sensor includes a plurality of pixels. Each of the plurality of pixels includes a photodetector that includes a photoelectric conversion element that outputs a detection signal in response to light incident thereon, a comparator that compares the detection signal of the photodetector with a ramp signal and outputs a comparison signal in response thereto, a plurality of first memory cells that store a first counting value corresponding to a first voltage level of the detection signal using the comparison signal of the comparator and output the first counting value through a plurality of transmission lines, and a plurality of second memory cells that store a second counting value corresponding to a second voltage level of the detection signal using the comparison signal of the comparator and output the second counting value through the plurality of transmission lines.