Solid-State Imaging Device Pixel Comparison Circuit Sensitivity
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Solution Overview
Problem
The existing solid-state imaging devices face a reduction in sensitivity due to line-sequential exposure methods, where comparison results are detected for each column, leading to inefficiencies in exposure and scanning.
Innovation Solution
A solid-state imaging device is designed with a comparison unit on a pixel-to-pixel basis that receives light, performs photoelectric conversion, compares currents with reference to potential lines, and stores signals when the comparison result inverts, using an inverter circuit, logic circuit, and positive feedback circuit to enhance signal processing and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If line-sequential exposure is used to detect comparison results for each column, then device complexity is reduced, but sensitivity deteriorates
Solution Approach 1:
The imaging device divides the pixel array into multiple columns, each with its own independent comparison unit and storage unit. This segmentation allows simultaneous exposure and comparison across all columns, eliminating the need for line-sequential operations while maintaining simplified control architecture.
Solution Approach 2:
The comparison unit performs photoelectric conversion and current comparison in advance within each pixel before readout. By completing the comparison operation preliminarily at the pixel level, the device captures all comparison results simultaneously during a single exposure period, preventing sensitivity loss that would occur with sequential line-by-line processing.
2Use of energy by stationary object
If comparison results are detected for each column sequentially, then power consumption is reduced, but productivity deteriorates
Solution Approach 1:
The device uses periodic clock signals to control the comparison operation and signal output timing. Each pixel's comparison unit operates synchronously with the clock signal during the exposure period, enabling all pixels to complete their comparison operations simultaneously in one periodic cycle, thereby achieving high productivity without excessive power consumption.
Solution Approach 2:
The comparison operation continues continuously across all pixels simultaneously during the exposure period. Unlike sequential column-by-column detection, all comparison units operate in parallel without interruption, maintaining continuous useful action that maximizes exposure efficiency while keeping power consumption manageable through synchronized operation.
3Device complexity
If A/D conversion is performed in a counter outside the pixel, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The A/D conversion function is extracted from the pixel and implemented as a counter circuit located outside the pixel array. This extraction simplifies the pixel internal circuit while the counter, positioned in the readout circuitry, performs digital conversion on the comparison results with high precision, resolving the contradiction between pixel simplicity and measurement accuracy.
Solution Approach 2:
The counter circuit acts as an intermediary between the pixel's comparison unit and the final digital output. It receives the analog comparison results from all pixels simultaneously and performs A/D conversion externally, ensuring measurement precision is maintained while allowing the pixel itself to remain structurally simple.
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 suppresses reduction in sensitivity and achieves low power consumption by allowing global shutter operations and efficient A/D conversion, improving the imaging device's performance.
Implementation Method 1
a comparison unit that receives light incident on a pixel, performs photoelectric conversion to generate a voltage
Data Source
AI summary
The present disclosure relates to a solid-state imaging device and an electronic apparatus that are capable of suppressing reduction in sensitivity. A current comparison unit receives light incident on a pixel, performs photoelectric conversion to generate a voltage, compares a current generated from the voltage with reference to a first potential line and a reference current generated with reference to a second potential line, the first potential line being one of a power supply line and a grounding line, the second potential line being another one of the power supply line and the grounding line, and outputs a comparison. A feedback unit returns a signal to a source side in the current comparison unit when the current is generated, the signal using the comparison result by the current comparison unit. The feedback unit can perform standby control in the current comparison unit.