Image Sensor Pad Segmentation for Stable Dark Signal Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The image quality of imaging devices degrades due to fluctuations in reference voltage caused by incident light, as described in Japanese Patent Application Laid-Open No. 2015-50706, which affects shading correction processing.
Innovation Solution
The imaging device incorporates a pixel array with separate pad portions for voltage supply lines in aperture and light-shielded regions, where the pad portions are configured differently to suppress voltage fluctuations, ensuring a stable dark signal independent of incident light, allowing for accurate correction processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pad portion supplies reference voltage to both aperture and light-shielded pixel regions, then device complexity is reduced, but voltage fluctuations occur due to incident light affecting the dark signal
Solution Approach 1:
The single pad portion is divided into two separate pad portions: a first pad portion for the aperture pixel region and a second pad portion for the light-shielded pixel region. This segmentation allows independent voltage supply to each region, preventing incident light from causing voltage fluctuations that would affect the dark signal in the light-shielded region.
Solution Approach 2:
Different pad portions are provided for different functional regions (aperture and light-shielded pixels) based on their specific requirements. The light-shielded region requires isolation from light-induced voltage fluctuations to maintain stable dark signal, while the aperture region receives light for normal imaging operations.
2Reliability
If separate pad portions are provided for aperture and light-shielded pixel regions, then dark signal stability is improved, but device complexity increases
Solution Approach 1:
The reference voltage supply is segmented into separate pad portions for aperture and light-shielded regions. Each pad portion independently supplies reference voltage to its respective region, ensuring that the light-shielded region's dark signal remains stable and unaffected by incident light on the aperture region.
Solution Approach 2:
The light-shielded pixel region is effectively extracted from the influence of incident light by providing it with a separate pad portion. This extraction isolates the dark signal measurement from the harmful effect of light-induced voltage fluctuations in the aperture region.
3Ease of manufacture
If reference voltage is supplied to light-shielded pixels affected by incident light, then manufacturing is simplified, but measurement precision of dark signal deteriorates
Solution Approach 1:
The voltage supply configuration is segmented into separate pad portions for aperture and light-shielded regions. This segmentation ensures that the dark signal measurement in the light-shielded region is not contaminated by voltage fluctuations caused by incident light on the aperture region, thereby improving measurement precision.
Solution Approach 2:
The light-shielded region is provided with a dedicated pad portion that supplies reference voltage independently of the aperture region. This local quality differentiation ensures that the dark signal measurement environment remains stable and free from light-induced interference.
Data Source
AI summary
An imaging device includes: a first pad portion that is connected to a voltage supply line in an aperture pixel region, and to which a reference voltage from outside of the semiconductor substrate is supplied; and a second pad portion that is connected to the voltage supply line in the light-shielded pixel region, and to which the reference voltage from outside of the semiconductor substrate is supplied, the second pad portion being separated from the first pad portion.