CMOS Image Sensor Thermal Shading Reduction via Segmented Heating
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
CMOS image sensors experience thermal dark shading due to non-uniform temperature across the chip, leading to uneven dark currents and visible shading patterns in low light conditions, which existing technologies have not effectively addressed.
Innovation Solution
Incorporating a plurality of heating elements and a controller within the CMOS image sensor to detect regions of thermal shading and automatically switch them on or off, ensuring uniform temperature and reducing thermal shading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heating elements are added to the CMOS image sensor chip, then thermal shading is reduced and temperature uniformity is improved, but device complexity and power consumption increase
Solution Approach 1:
The heating system is segmented into multiple independent heating elements distributed across different regions of the CMOS image sensor chip. Each heating element can be independently controlled to address thermal shading in specific regions, allowing targeted temperature compensation without uniformly heating the entire chip, thus managing complexity while improving temperature uniformity.
Solution Approach 2:
Different regions of the CMOS image sensor chip are heated with different intensities based on their specific thermal shading characteristics. The controller activates heating elements selectively in regions where thermal shading is detected, providing localized heating to compensate for temperature variations in specific areas rather than applying uniform heating across the entire chip.
2Temperature
If heating elements are continuously activated, then thermal shading is reduced, but power consumption increases
Solution Approach 1:
The heating elements are activated periodically rather than continuously. The controller monitors thermal shading conditions and activates heating elements only during periods when thermal shading is detected and compensation is needed. During periods when temperature uniformity is already achieved or imaging is not active, the heating elements remain inactive, reducing overall power consumption while maintaining temperature uniformity when required.
Solution Approach 2:
The heating system transitions from a static, continuous operation mode to a dynamic, condition-based operation mode. The controller dynamically adjusts the activation state of heating elements based on real-time detection of thermal shading conditions, activating heating only when and where needed to maintain temperature uniformity, thereby optimizing power consumption.
3Temperature
If more heating elements are added to cover all regions, then thermal shading reduction is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
Instead of using a single large heating element or uniformly distributed dense array, the heating system is segmented into a selective array of heating elements positioned in regions where thermal shading is most problematic. This segmented approach provides effective thermal shading reduction in critical areas while minimizing the total number of heating elements, thereby simplifying manufacturing processes and reducing costs.
Solution Approach 2:
Heating elements are strategically positioned and activated only in regions where thermal shading is most severe, rather than uniformly distributing heating capability across the entire chip. This localized approach concentrates heating resources where they are most needed, reducing the total number of heating elements required and simplifying manufacturing while still achieving effective thermal shading reduction in the most problematic areas.
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 thermal shading by maintaining uniform temperature across the image sensor, improving image quality in low light conditions without increasing power consumption during peak usage.
Implementation Method 1
In an image sensor, each light receiving element outputs a signal having an integrated light component and an integrated dark current component. A dark current is an undesirable current that integrates as charge in a photodiode of pixels in a complementary metal-oxide-semiconductor (CMOS) image sensor and is temperature dependent.
Data Source
AI summary
A method for reducing thermal shading in a complementary metal-oxide-semiconductor (CMOS) image sensor is provided. The method includes: detecting one or more regions in a CMOS image sensor in which thermal shading occurs, the CMOS image sensor including a plurality of heating elements in a chip; automatically switching a subset of the plurality of heating elements to turn on based on the detected one or more regions; and automatically switching the subset of the plurality of heating elements to turn off in an active power consumption phase of the CMOS image sensor.