Image Sensor Pixel Idle Charge Dissipation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid-state image sensors, such as CMOS image sensors, face the issue of blooming during idle periods, where accumulated electrical charge can lead to saturation and spillover into neighboring pixels, causing image artifacts like blurring.
Innovation Solution
A control circuit in the image sensor identifies when a pixel is in an idle period and performs a blooming operation, such as an idle reset or maintaining a reset state, to dissipate or transfer electrical charge, thereby reducing the likelihood of saturation and blooming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel remains in idle period without charge dissipation, then the pixel structure is simple and operation is continuous, but electrical charge accumulates at the photosensitive sensor causing saturation and blooming
Solution Approach 1:
The control circuit performs preliminary action by detecting the idle period state before charge saturation occurs and initiating blooming operations (reset or charge transfer) during the idle period to prevent charge accumulation. This proactive approach resolves the contradiction by maintaining reliability through preventive charge management while keeping the device structure relatively simple.
Solution Approach 2:
The pixel structure utilizes existing components (photosensitive sensor, floating diffusion node, transfer transistor) to perform self-service charge management during idle periods. The blooming operation leverages the natural idle period for charge dissipation without requiring additional dedicated structures, thus improving reliability while minimizing device complexity.
2Reliability
If blooming operation is performed during integration period, then charge accumulation is reduced, but the photosensitive sensor measurement is affected and image quality deteriorates
Solution Approach 1:
The control circuit performs preliminary detection of the integration period state and prevents blooming operations during this critical measurement phase. By timing the blooming operation to occur only during idle periods when no measurement is taking place, the system maintains measurement precision while still achieving charge saturation prevention.
Solution Approach 2:
The control circuit uses feedback from period detection (identifying whether the pixel is in idle or integration period) to dynamically control the timing of blooming operations. This feedback mechanism ensures that charge management actions are synchronized with the operational state, preventing interference with measurements while maintaining effective charge control.
3Reliability
If idle reset is applied to dissipate electrical charge, then blooming probability is reduced, but additional energy is consumed and reset operation time is required
Solution Approach 1:
The idle reset operation is applied periodically during idle periods rather than continuously. The control circuit monitors the idle period and applies reset operations at appropriate intervals to dissipate accumulated charge. This periodic approach maintains blooming prevention effectiveness while reducing overall energy consumption compared to continuous reset.
Solution Approach 2:
The system changes the operational parameter of the photosensitive sensor between accumulation mode (during integration) and dissipation mode (during idle period with reset). By switching the sensor state based on the operational period, the system achieves effective charge management with minimal energy expenditure, applying reset only when the pixel is naturally in idle state.
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 the probability of blooming by managing electrical charge during idle periods, thereby improving image quality by preventing charge spillover and maintaining pixel accuracy.
Implementation Method 1
the blooming operation comprises applying an idle reset to the pixel to dissipate electrical charge that as accumulated at the photosensitive sensor
Implementation Method 2
the blooming operation comprises transferring, during the idle period, at least a portion of the accumulated electrical charge from the photosensitive sensor to another portion of the pixel
Data Source
AI summary
Among other things, techniques and systems are provided for identifying when a pixel of an image sensor is in an idle period. A flag is utilized to differentiate when the pixel is in an idle period and when the pixel is in an integration period. When the flag indicates that the pixel is in an idle period, a blooming operation is performed on the pixel to reduce an amount of electrical charge that has accumulated at the pixel or to mitigate electrical charge from accumulating at the pixel. In this way, the blooming operation reduces a probability that the photosensitive sensor becomes saturated during an idle period of the pixel, and thus reduces the likelihood of electrical charge from a pixel that is not intended contribute to an image from spilling over and potentially contaminating a pixel that is intended to contribute to the image.