Imaging Element Pixel Region Well Potential Control
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Solution Overview
Problem
Existing imaging elements face challenges in reducing power consumption without deteriorating image quality, as lowering the power supply potential affects pixel characteristics and image quality, and using a negative ground potential alters transistor operating characteristics, making it difficult to maintain optimal pixel performance.
Innovation Solution
The imaging device incorporates a pixel region with a photoelectric conversion unit connected to a well potential set as a negative potential, and a peripheral circuit region with an analog-to-digital converter, where the well potential of the pixel region is lower than that of the peripheral circuit region, allowing for independent control of power supply and ground potentials to maintain image quality while reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the power supply potential is reduced to achieve low power consumption, then power consumption is reduced, but pixel characteristic changes and image quality is greatly deteriorated
Solution Approach 1:
The imaging element is divided into two separate semiconductor substrates: a first substrate for the pixel region and a second substrate for the peripheral circuit region. This segmentation allows independent optimization of power supply potentials for each region, enabling low power consumption in peripheral circuits while maintaining sufficient power for high-quality image capture in the pixel region.
Solution Approach 2:
Different power supply potentials are applied to different regions: the pixel region operates at a higher potential (e.g., 1.8V or 3.3V) to maintain optimal pixel characteristics and image quality, while the peripheral circuit region operates at a lower potential (e.g., 1.2V or 0.9V) to reduce power consumption. This local differentiation of power supply quality resolves the contradiction between power savings and image quality.
2Object-generated harmful factors
If the ground potential of the light receiving element is set to negative potential, then noise is decreased and low-voltage driving is achieved, but transistor operating characteristic changes and pixel characteristic becomes suboptimal
Solution Approach 1:
The imaging element separates the pixel region and peripheral circuit region onto different substrates, allowing the pixel region to maintain a conventional 0V ground reference that optimizes transistor operating characteristics, while the peripheral circuit region can utilize negative ground potential for noise reduction. This segmentation enables both benefits without compromising pixel performance.
Solution Approach 2:
The patent introduces separate power supply potential generation units for each region, acting as intermediaries that provide appropriately tailored power supply conditions. The first power supply potential generation unit provides optimal potentials for pixel transistors, while the second unit provides low-power potentials for peripheral circuits, thereby mediating between conflicting requirements.
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 improved signal processing and image acquisition time while reducing power consumption, maintaining image quality by controlling pixel characteristics and optimizing transistor operating characteristics.
Implementation Method 1
a photoelectric conversion unit photoelectrically converts incident light
Data Source
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AI summary
An imaging element comprises a photoelectric conversion unit formed in a pixel region and configured to convert light into electrical charge. Further, the imaging element includes a transistor formed in the pixel region and configured to transfer electric charge from the photoelectric conversion unit. The photoelectric conversion unit of the imaging element may be connected to a well of the pixel region, where the well of the pixel region has a negative potential.