SPAD Pixel Array Thinning for Solid-State Imaging Power Reduction
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Solution Overview
Problem
Solid-state imaging apparatus using SPAD pixels faces high power consumption when imaging in bright scenes due to the multiplication of thousands of photons, leading to excessive electron generation.
Innovation Solution
The apparatus thins a part of the SPAD pixels on the pixel array section when illuminance exceeds a reference level, reducing power consumption by controlling the driving of SPAD pixels for each pixel or block unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all SPAD pixels are operated in bright scenes, then imaging sensitivity is maintained, but power consumption becomes extremely high
Solution Approach 1:
The pixel array is divided into multiple blocks, and within each block, certain SPAD pixels are selected as reference pixels while others are imaging pixels. This segmentation allows the system to process information through reference pixels that consume less power, thereby reducing overall power consumption while maintaining imaging capability through the distributed block structure
Solution Approach 2:
Reference pixels are extracted from the pixel array to perform illuminance detection and signal correction functions. These reference pixels are taken out from the full imaging operation, allowing the majority of pixels to operate in a lower-power mode while still maintaining image quality through the correction data provided by the extracted reference pixels
2Measurement precision
If SPAD pixels multiply tens of thousands of photons, then one-photon detection sensitivity is achieved, but hundreds of millions of electrons are generated in bright scenes
Solution Approach 1:
Instead of having all pixels perform full avalanche multiplication, only reference pixels perform the complete multiplication process. Imaging pixels operate with reduced multiplication or in a different mode, providing partial action that is sufficient for the imaging function while avoiding the excessive electron generation that would occur if all pixels performed full multiplication
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 allows for imaging at lower power consumption by selectively thinning SPAD pixels during high illuminance conditions, thereby reducing overall power usage.
Implementation Method 1
an electron photoelectrically converted from one photon passes
Implementation Method 2
the electron is multiplied tens of thousands times
Data Source
AI summary
The present technology relates to a solid-state imaging apparatus and a driving method that can perform imaging at lower power consumption.By providing the solid-state imaging apparatus including a pixel array section on which a plurality of SPAD pixels is two-dimensionally arranged, in which in a case where illuminance becomes first illuminance higher than reference illuminance, a part of the SPAD pixels of the plurality of pixels arranged on the pixel array section is thinned, it is possible to image at lower power consumption. The present technology can be applied to an image sensor, for example.