Solid-State Imaging Pixels With Multi-Accumulator Signal Averaging
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Solution Overview
Problem
Multi-tap imaging sensors face challenges due to non-uniformity in charge accumulator characteristics, leading to reduced measurement precision and potential motion artifacts due to increased read time by pixel row units.
Innovation Solution
A solid-state imaging device with a pixel array and driver configuration that controls transfer transistors to accumulate and convert electric charge into digital values, averaging non-uniformities across charge accumulators and reducing read time by pixel units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple charge accumulators are used in each pixel for TOF measurement, then measurement precision is improved, but non-uniformity in charge accumulator characteristics reduces measurement precision
Solution Approach 1:
The patent combines multiple charge accumulators (first and second charge accumulators) within a single pixel to perform correlated double sampling. By merging the readout of multiple accumulators and processing their signals together through the ADC and adder circuits, the system achieves measurement precision that compensates for individual accumulator non-uniformities.
Solution Approach 2:
The patent implements feedback by using the first charge accumulator signal to generate a first digital value and the second charge accumulator signal to generate a second digital value, then adding them together through the adder circuit. This feedback mechanism allows the system to continuously process and correct for non-uniformities in the charge accumulator characteristics.
2Reliability
If pixel signals are read by pixel row units for each subframe, then charge accumulation is completed, but read time increases causing motion artifacts
Solution Approach 1:
The patent segments the readout process by independently reading out the first and second charge accumulators within each pixel during different subframes. This segmentation allows parallel processing of multiple pixels across different time periods, reducing the total read time while maintaining complete charge accumulation for TOF measurement.
Solution Approach 2:
The patent dynamically adjusts the readout timing by controlling transfer transistors to selectively transfer charges from the photoelectric converter to different charge accumulators in different subframes. This dynamic control enables flexible readout scheduling that optimizes both charge accumulation completion and read time efficiency.
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
Improves measurement precision and prevents motion artifacts by averaging non-uniformities in charge accumulator characteristics and shortening read time.
Implementation Method 1
a photoelectric converter configured to photoelectrically convert light to generate electric charge
Data Source
AI summary
Provided is a solid-state imaging device including a pixel including a photoelectric converter configured to photoelectrically convert light to generate electric charge, a plurality of charge accumulators each configured to accumulate the electric charge, and a plurality of transfer controllers configured to respectively control transfer of the electric charge to the plurality of charge accumulators from the photoelectric converter, a converter configured to generate a digital value that is based on the amount of electric charge accumulated in the plurality of charge accumulators, an adder configured to add the generated digital value to a digital value previously stored in the memory, and a driver configured to control the plurality of transfer controllers to store the resulting value of the addition in the memory.