Image Sensor Pixel Array Segmentation for Frame Rate Control
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Solution Overview
Problem
Electronic cameras face a trade-off between frame rate and image resolution due to noise introduced by high-speed data reading from image sensors, with larger sensors providing higher resolution but slower frame rates and smaller sensors offering faster frame rates at the cost of reduced resolution.
Innovation Solution
The solution involves triggering pixels individually to capture either high-resolution images using all pixels or low-resolution images using fewer pixels, eliminating the need for a separate shutter array and reducing device complexity, by using row and column select signals generated by shift registers to control each pixel's exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of pixels are used to maintain high image resolution, then image resolution is improved, but frame rate decreases due to slower data reading speed
Solution Approach 1:
The patent divides the pixel array into multiple subsets that can be exposed and read out separately. By segmenting the pixels into subsets, the system can read out data from smaller portions of the array more quickly, thereby achieving higher frame rates while maintaining the ability to capture high-resolution images when all pixels are activated simultaneously.
Solution Approach 2:
The patent implements dynamic control over which pixels are exposed and read out at any given time. The system can dynamically adjust the number of active pixels based on the capture mode (still image vs. video), allowing flexible switching between high resolution and high frame rate operations as needed.
2Productivity
If high-speed data reading is performed to achieve high frame rate, then frame rate is improved, but read noise increases which lowers signal quality
Solution Approach 1:
By segmenting the pixel array into subsets and reading out data from smaller portions at a time, the system reduces the total data readout rate required for each subset, thereby minimizing read noise while maintaining high frame rate capability. The signal quality is preserved because only the necessary subset of pixels is read at any given moment.
3Ease of operation
If a separate shutter array is added to control individual pixel exposure, then individual pixel control is improved, but device size and complexity increase
Solution Approach 1:
The patent merges the shutter control function with the existing pixel circuitry by using shared control lines that can be selectively activated. Instead of adding a separate shutter array, the system uses the existing row and column select signals to control pixel exposure, thereby maintaining individual pixel control while avoiding additional hardware complexity.
Solution Approach 2:
The row and column select signals serve multiple functions: they control both the exposure timing of pixels and the data readout sequence. This multi-functional approach eliminates the need for dedicated shutter control hardware, reducing device complexity while maintaining full pixel control capability.
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 allows for higher frame rates in movie capture while maintaining still image resolution, with the ability to adjust the balance between resolution and frame rate, and embeds low-resolution images within high-resolution frames for versatile image capture.
Implementation Method 1
an array of pixels 6 arranged in a number of pixel subsets S1 to SN such that the pixels in each subset can be triggered individually to detect incident light
Data Source
Figure 1a~3
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Figure 6~7
AI summary
An image sensor has a plurality of pixels arranged in an array, a selection means for selecting individual pixels in the array, and a shutter means for transmitting a shutter signal to the pixels. The pixels are constructed and arranged to sense incident light only when both selected and in receipt of a shutter signal. The pixels in said array can thus be triggered individually to capture light at different times.