Image Sensor Pixel Charge Sharing for Wider Dynamic Range
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Solution Overview
Problem
Existing solid-state image pickup devices face challenges in switching conversion efficiency without increasing pixel area, particularly in managing dynamic range across varying light intensities, as they require additional components for charge accumulation and control, leading to reduced efficiency and potential saturation.
Innovation Solution
A solid-state image pickup device with a configuration that includes multiple pixels, each equipped with a photoelectric conversion section, charge holding sections, and a pixel connection section that allows charge sharing between pixels, along with a pixel reset section to manage charge distribution and reset processes, utilizing MOS transistors for efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a capacity switching switch and charge accumulation section are used to switch conversion efficiency, then the dynamic range is widened and visibility is improved, but the pixel area is increased
Solution Approach 1:
The patent merges the charge accumulation function into the photoelectric conversion section itself by extending the photoelectric conversion region to serve dual purposes: converting light to charge and accumulating charge. This eliminates the need for separate charge accumulation sections and capacity switching switches, thereby maintaining small pixel area while achieving dynamic range extension through variable conversion efficiency
Solution Approach 2:
The photoelectric conversion section is designed to perform multiple functions: it acts as both the light-to-charge conversion element and the charge accumulation storage. By making the photoelectric conversion region variable in size, it can adapt to different lighting conditions (low-light vs. high-light) without requiring dedicated separate components, thus achieving universal operation across varying dynamic range requirements
2Reliability
If the capacity of the charge voltage conversion section is increased to prevent saturation in high-light intensity, then the conversion efficiency is reduced, but additional components are required
Solution Approach 1:
The patent combines the charge accumulation capacitance with the photoelectric conversion section by extending the photoelectric conversion region. This integrated design eliminates the need for separate charge accumulation capacitors and capacity switching switches, reducing device complexity while maintaining the ability to prevent saturation through variable conversion efficiency
Solution Approach 2:
The patent implements dynamic adjustment of the photoelectric conversion region size to adapt to varying light conditions. In high-light intensity, the conversion region is reduced to decrease conversion efficiency and prevent saturation; in low-light intensity, the conversion region is expanded to increase conversion efficiency and improve signal-to-noise ratio. This dynamic behavior is achieved through selective connection of pixel regions rather than additional active components
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 configuration enables efficient switching of conversion efficiency while maintaining a compact pixel area, enhancing dynamic range and preventing image signal saturation across different light conditions.
Implementation Method 1
a photoelectric conversion section that generates a charge according to irradiated light
Data Source
AI summary
A solid-state image pickup device includes a plurality of pixels, a pixel connection section, and a pixel reset section. The plurality of pixels each include a photoelectric conversion section that generates a charge according to irradiated light, a charge holding section that holds the generated charge, and a signal generation section that generates as an image signal a signal according to the held charge. The pixel connection section conducts between charge holding sections of the plurality of pixels and thereby allows each of the charge holding sections of the plurality of pixels to hold the charge that has been generated by the photoelectric conversion section of one pixel of the plurality of pixels. The pixel reset section discharges and resets the charge of the respective charge holding sections of the plurality of pixels when the pixel connection section conducts between the respective charge holding sections of the plurality of pixels.