Difference-Detection Pixel Circuit for Low-Power Imaging
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Solution Overview
Problem
Current imaging devices face challenges in reducing power consumption, achieving low power consumption, small size, adjustable light sensitivity, high on-state and low off-state current transistors, wide dynamic range, long data holding time, minimal distortion during subject movement, wide temperature range operation, low noise, high light sensitivity, and cost-effectiveness while maintaining high reliability.
Innovation Solution
The imaging device incorporates a pixel circuit with multiple transistors, including oxide semiconductors, and photoelectric conversion elements with selenium, employing a difference detection mode to reduce power consumption and adjust light sensitivity, utilizing oxide semiconductors with In, Zn, and other metals, and selenium-based photoelectric conversion elements to achieve low off-state current and high on-state current, and a capacitor for improved performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If imaging data of every frame is output to external device, then complete imaging data is provided, but power consumption increases
Solution Approach 1:
The patent extracts and outputs only the essential imaging data by comparing current frame with previous frame, sending only frames with detected changes to the external device. This eliminates redundant data transmission while maintaining the completeness of meaningful imaging information.
Solution Approach 2:
Instead of transmitting all imaging data, the patent applies partial action by selectively transmitting only necessary frames (those with detected changes), reducing overall data transmission volume and power consumption while maintaining adequate imaging coverage.
2Loss of energy
If oxide semiconductor transistors are used, then off-state current is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs parameter changes by optimizing the formation conditions of oxide semiconductor films, including controlling deposition temperature, oxygen partial pressure, and film thickness to achieve the desired electrical characteristics with relaxed manufacturing tolerances.
Solution Approach 2:
The patent uses composite material structures combining oxide semiconductor layers with other functional materials (such as tungsten electrodes and insulating layers) to achieve both low off-state current and manufacturability through standardized fabrication processes.
3Measurement precision
If selenium-based photoelectric conversion elements are used, then light sensitivity is enhanced, but device complexity increases
Solution Approach 1:
The patent merges the selenium-based photoelectric conversion layer with the transistor structure, integrating light detection and signal processing functions into a unified pixel unit, thereby enhancing light sensitivity without proportionally increasing overall device complexity.
Solution Approach 2:
The selenium-based photoelectric conversion element serves multiple functions: light detection, charge generation, and signal initiation, reducing the need for separate components and simplifying the overall device architecture despite the specialized material used.
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 results in an imaging device with reduced power consumption, adjustable sensitivity, wide dynamic range, minimal distortion, and operational reliability across a wide temperature range, while maintaining high light sensitivity and cost-effectiveness.
Implementation Method 1
a first photoelectric conversion element, a second photoelectric conversion element
Data Source
AI summary
An imaging device with low power consumption is provided. The pixel of the imaging device includes first and second photoelectric conversion elements, and first to fifth transistors. A cathode of the first photoelectric conversion element is electrically connected to the first transistor. An anode of a second photoelectric conversion element is electrically connected to the second transistor. Imaging data of a reference frame is obtained using the first photoelectric conversion element, and then imaging data of a difference detection frame is obtained using the second photoelectric conversion element. After the imaging data of the difference detection frame is obtained, a first potential that is a potential of a signal output from the pixel and a second potential that is a reference potential are compared. Whether or not there is a difference between the imaging data of the reference frame and the imaging data of the difference detection frame is determined using the first potential and the second potential.