Image Sensor Potential Control for Charge Leakage Prevention
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Solution Overview
Problem
Conventional image sensors face issues with signal integration from photodiodes due to differences in sensitivity and light incidence, leading to charge leakage and inappropriate image output when one photodiode saturates, affecting focus detection and image acquisition.
Innovation Solution
The image sensor employs a potential control mechanism to adjust the separation area potential between photodiodes, allowing selective setting of electric potentials to prevent charge leakage and enable separate reading of signals from each photodiode, even when one is saturated, using a potential control switch to manage the potential barrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If signals from multiple photodiodes are added to obtain an image signal, then productivity is improved by acquiring both focus detection and image signals through a single driving operation, but manufacturing precision deteriorates when photodiodes have different sensitivities or incident light amounts causing charge leakage and inappropriate image output
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the electric potential of the separation area between photodiodes. When one photodiode saturates, the separation area's potential is changed to prevent charge leakage to other photodiodes, thereby maintaining image output accuracy while preserving the efficiency of single-operation signal acquisition
Solution Approach 2:
The patent implements dynamics by making the separation area potential adjustable rather than fixed. The potential control switch enables the separation area to adapt its electric potential based on the saturation state of photodiodes, allowing the system to maintain precision under varying operating conditions while keeping the photodiode array structure intact
2Reliability
If the separation area potential is increased to prevent charge leakage between photodiodes, then reliability is improved by maintaining signal integrity, but device complexity increases due to the need for potential control switches and multiple potential settings
Solution Approach 1:
The patent applies segmentation by dividing the control mechanism into discrete potential control switches, each independently controlling the separation area potential. This modular approach allows precise control of charge leakage prevention while maintaining manageable system complexity through functional decomposition
Solution Approach 2:
The patent uses the separation area as an intermediary element between photodiodes. By controlling the potential of this intermediate region, the system prevents direct charge leakage between photodiodes while using simple potential control switches rather than complex individual photodiode control mechanisms
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 ensures accurate and reliable signal output by preventing charge leakage and maintaining appropriate image quality, even under conditions of varying sensitivity and light incidence, enhancing focus detection and image acquisition processes.
Implementation Method 1
an electric potential of a separation portion that separates the plurality of pixels is taken as a reference potential, the plurality of electric potentials include a first electric potential that is higher than the reference potential
Implementation Method 2
When light is incident on a PD, an electric charge is generated with a certain sensitivity by photoelectric conversion
Data Source
AI summary
An image sensor comprises a plurality of pixels, and each pixel having: a plurality of photoelectric conversion units configured to receive light fluxes that pass through different exit pupil regions of an optical system disposed on an object side of the image sensor and accumulate charges, respectively; a separation portion configured to separate the photoelectric conversion units; and setting means configured to selectively set an electric potential of the separation portion to any one of a plurality of electric potentials. Signals can be separately read out from the photoelectric conversion units. Taking an electric potential of a separation portion that separates the plurality of pixels as a reference potential, the plurality of electric potentials include first to third electric potentials; higher than the reference potential, lower than the reference potential, and higher than the reference potential and lower than the first electric potential.