HDR Image Sensor Pixel Sharing for Low-Noise Single-Frame Readout
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Solution Overview
Problem
Staggered HDR technology increases noise and reduces frame rate due to multiple readout operations and exposure time differences in image sensing devices.
Innovation Solution
An image sensing device with a pixel array that includes pixels sharing a floating diffusion region, allowing for simultaneous readout of signals from different exposure times within a single frame, reducing noise and maintaining frame rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If staggered HDR technology uses multiple readout operations to capture different exposure times, then HDR image quality is improved, but noise increases and frame rate decreases
Solution Approach 1:
The patent merges multiple pixel signals (reset signal, first pixel signal, second pixel signal) into a single readout operation by sharing the floating diffusion region among multiple pixels with different exposure times. This combining approach allows simultaneous reading of all signals without requiring separate readout operations, thereby maintaining HDR image quality while reducing noise and preserving frame rate.
Solution Approach 2:
The floating diffusion region is designed to serve multiple functions: it acts as the charge accumulation node for pixels with different exposure times, the reset signal generation node, and the signal readout node. This multi-functionality allows a single readout operation to capture all necessary signals for HDR imaging, eliminating the need for multiple readout operations and reducing noise.
2Measurement precision
If staggered HDR technology performs multiple readout operations for different exposure times, then HDR image quality is improved, but frame rate is reduced
Solution Approach 1:
The patent combines multiple signal readout operations into a single operation by having multiple pixels (with different exposure times) share the same floating diffusion region and readout path. This allows the reset signal, first pixel signal, and second pixel signal to be read out simultaneously in one operation, maintaining HDR image quality while preserving frame rate.
Solution Approach 2:
The patent performs preliminary charge accumulation in the shared floating diffusion region for multiple pixels during different exposure times before a single readout operation. This preliminary action allows all necessary signals to be prepared and ready for simultaneous reading, eliminating the need for multiple sequential readout operations and maintaining high frame rate.
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
The solution effectively reduces noise and maintains frame rate by enabling high dynamic range image generation with reduced readout operations, achieving high-sensitivity and low-sensitivity images within a single frame.
Implementation Method 1
a first photoelectric conversion element configured to generate and accumulate charges based on intensity of light
Data Source
AI summary
An image sensing device for generating a high dynamic range (HDR) image is disclosed. The image sensing device includes a first pixel configured to generate a first pixel signal based on light received during a first exposure time, and a second pixel configured to share a floating diffusion region with the first pixel and to generate a second pixel signal based on light received during a second exposure time different from the first exposure time. When the floating diffusion region is reset based on a pixel reset signal in a first period, a reset signal is read out, the first pixel signal is read out in a second period, and the second pixel signal is read out in a third period. The first period, the second period, and the third period are included in one frame.