Imaging Device Dual Exposure Pixel Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional imaging devices with global electronic shutter function lack improvements in dynamic range and focus detection speed.
Innovation Solution
The imaging device employs a dual exposure period strategy, where a first group of pixels accumulates charge for a shorter exposure period and a second group for a longer exposure period, with overlapping periods, allowing for improved dynamic range and focus detection by optimizing charge transfer and holding mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single exposure period is used for all pixels, then the imaging device structure is simple, but the dynamic range is limited and focus detection speed is slow
Solution Approach 1:
The pixel array is divided into multiple groups (first group and second group) that operate with different exposure periods. The first group uses a shorter exposure period while the second group uses a longer exposure period, allowing simultaneous capture of different dynamic range information from different pixel regions, thereby improving overall dynamic range without requiring a completely complex reconfigurable system.
Solution Approach 2:
The imaging device implements dynamic exposure control where different pixel groups can be exposed for different durations simultaneously. This dynamic approach allows the system to adapt exposure timing to specific imaging needs (e.g., focusing on certain regions or capturing transient events) while maintaining a relatively simple overall architecture compared to fully reconfigurable systems.
2Speed
If a single exposure period is used for all pixels, then the device operation is simple, but focus detection speed is slow
Solution Approach 1:
The pixel array is segmented into multiple groups with different exposure timing. The first group completes exposure faster and can be read out sooner, enabling quicker focus detection signals to be generated and processed. This segmentation allows the system to achieve fast focus detection without requiring every pixel to undergo a lengthy uniform exposure process.
Solution Approach 2:
The first group of pixels performs a preliminary, faster exposure and readout cycle that can provide initial focus detection information before the second group completes its longer exposure. This preliminary action enables the system to quickly assess focus status and make adjustments without waiting for all pixels to complete their full exposure sequences.
3Adaptability or versatility
If exposure periods are extended to improve dynamic range, then saturation charge amounts increase, but image quality deteriorates due to positional deviations
Solution Approach 1:
By dividing pixels into multiple groups with different exposure periods, the system can capture high dynamic range information without forcing all pixels to undergo the same extended exposure. The first group captures fast-changing events with shorter exposure, while the second group captures detailed information with longer exposure, reducing positional deviations when combining results.
Solution Approach 2:
The system changes the exposure time parameter differentially across pixel groups rather than uniformly. By adjusting exposure duration as a variable parameter that differs by pixel group, the system optimizes both dynamic range capture and positional accuracy, avoiding the trade-off that would result from uniform extended exposure of all pixels.
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 imaging device's dynamic range and focus detection speed, reducing saturation charge amounts and improving image quality by aligning exposure periods and reducing positional deviations in combined images.
Implementation Method 1
a photoelectric conversion unit that generates charge by photoelectric conversion
Data Source
AI summary
An imaging device includes pixels including a photoelectric conversion unit, a holding unit that holds charge, and an amplifier unit. The pixels include a first group outputting a signal based on charge generated during a first exposure period, and a second group outputting a signal based on charge generated during a second exposure period longer than the first exposure period. The pixel belonging to the second group includes in the second exposure period a first period during which the charge generated in the photoelectric conversion unit is accumulated in the photoelectric conversion unit, and the charge held by the holding unit is transferred to the amplifier unit, and a second period during which the charge generated during the first period is held in the holding unit, and the charge generated after the first period is held by one of the photoelectric conversion unit and the holding unit.