CMOS Pixel Array Dual Mode Ambient Light Detection
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Solution Overview
Problem
Portable electronic devices that include both CMOS imaging devices for capturing images and stand-alone ambient light detectors face challenges in power consumption and increased manufacturing costs due to the need for separate components for image capture and light detection.
Innovation Solution
Integrating a CMOS imaging device to perform both photo image capture and ambient light detection by operating the pixel array in dual modes, using a multiplexer, integration circuit, differential amplifier, comparator, and control logic unit to detect ambient light conditions with reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stand-alone ambient light detector is used, then ambient light detection function is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The pixel array of the CMOS imaging device is designed to perform multiple functions: image capture during photo mode and ambient light detection during ambient light detection mode. By configuring pixels to operate in different modes through control signals, the same hardware structure achieves both imaging and light sensing capabilities, eliminating the need for separate ambient light detector components.
Solution Approach 2:
The patent combines the ambient light detection function with the existing CMOS imaging device structure. The pixel array, readout circuitry, and control logic are merged into a single integrated system that can switch between image capture and ambient light detection modes, reducing overall device complexity and manufacturing cost.
2Adaptability or versatility
If a stand-alone ambient light detector is used, then ambient light detection function is achieved, but manufacturing cost increases
Solution Approach 1:
The pixel array is designed as a universal component that can perform both image capture and ambient light detection. This multi-functionality eliminates the need for separate ambient light detector components, reducing bill of materials cost and simplifying the manufacturing process by requiring only one type of sensor array.
Solution Approach 2:
By merging the ambient light detection capability into the existing CMOS imaging device fabrication process, the patent achieves cost efficiency. The same semiconductor manufacturing steps produce both imaging pixels and ambient light sensing pixels, eliminating the need for separate component assembly and reducing overall manufacturing cost.
3Adaptability or versatility
If the pixel array operates in dual modes, then ambient light detection is achieved, but power consumption management becomes complex
Solution Approach 1:
The system implements periodic ambient light detection by switching the pixel array between image capture mode and ambient light detection mode in time intervals. During ambient light detection mode, pixels accumulate charge from ambient light without requiring full readout operations, reducing power consumption compared to continuous operation. The control logic manages these periodic mode switches to balance detection accuracy with energy 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
This integration reduces manufacturing complexity and costs while minimizing power usage, allowing for efficient ambient light detection and image capture in portable devices, effectively managing backlight brightness and enhancing power efficiency.
Implementation Method 1
Each pixel including a photosensor, for example, a photogate, photoconductor or a photodiode overlying a substrate for accumulating photo-generated charge
Data Source
AI summary
An imaging method and apparatus which use a pixel array for capturing images and for measuring ambient light conditions.