Floating Diffusion Switching for Dynamic Range and Noise Control
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Solution Overview
Problem
Existing image pickup apparatuses face challenges in simultaneously expanding the dynamic range and reducing noise, particularly when adjusting the capacity of floating diffusion units (FD) in image sensing devices.
Innovation Solution
An image pickup apparatus with a control method that includes a switch unit to selectively connect or disconnect floating diffusion units to connection lines, allowing for sequential or collective connection, thereby optimizing FD capacity based on image shooting conditions to balance dynamic range and noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the capacity of floating diffusion units is increased to expand dynamic range, then the dynamic range increases, but noise also increases
Solution Approach 1:
The patent applies dynamics by making the FD capacity adjustable rather than fixed. The switch unit dynamically connects or disconnects floating diffusion units to connection lines based on image shooting conditions, allowing the system to adapt the FD capacity in real-time. This resolves the contradiction by enabling the system to use larger FD capacity when dynamic range is needed and smaller FD capacity when noise reduction is prioritized.
Solution Approach 2:
The patent segments the floating diffusion units into multiple independent units that can be selectively connected or disconnected. By dividing the FD structure into separable units, the system can control the effective capacity by connecting only the necessary number of units to connection lines, thereby adjusting the balance between dynamic range and noise for different imaging conditions.
2Object-affected harmful factors
If the capacity of floating diffusion units is decreased to reduce noise, then noise decreases, but the dynamic range becomes narrow
Solution Approach 1:
The system dynamically adjusts FD capacity by controlling the switch unit to connect or disconnect floating diffusion units based on imaging conditions. For low-light or high-sensitivity scenarios, the system connects more FD units to increase capacity and dynamic range. For high-light scenarios, it disconnects units to reduce capacity and minimize noise, thus resolving the contradiction adaptively.
Solution Approach 2:
The patent applies local quality by making different portions of the FD units have different connection states. Not all FD units are uniformly connected or disconnected; instead, the switch unit selectively connects specific FD units to connection lines based on the specific imaging requirements, allowing localized optimization of capacity versus noise reduction.
3Measurement precision
If pieces of pixel data in the same column are added together to expand dynamic range, then the dynamic range expands, but it becomes difficult to simultaneously reduce noise
Solution Approach 1:
The patent resolves this contradiction by dynamically controlling which floating diffusion units are connected to connection lines. When pixel data from the same column need to be added together to expand dynamic range, the switch unit connects the corresponding FD units to enable signal summation. When noise reduction is prioritized, the switch unit disconnects FD units to prevent unwanted signal combination, thus adaptively managing the trade-off between dynamic range expansion and noise reduction.
Data Source
AI summary
An image pickup apparatus capable of ensuring a dynamic range suitable for an image shooting condition and capable of reducing noise. The image pickup apparatus includes an image sensing device having floating diffusion units that are provided corresponding to pixels and that convert electrical charges accumulated in the pixels into voltage signals, which are output as pixel signals from pixel amplifiers. At that time, according to an image shooting condition, at least parts of connection switches corresponding to the floating diffusion units are sequentially turned on or all the connection switches are turned off, whereby the connection switches are connected to or disconnected from connection lines to thereby change capacity components connected to pixel amplifiers. This contributes to dynamic range expansion or noise reduction.