Optical Sensor Dynamic Range via Pixel Segmentation
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Solution Overview
Problem
Current optical sensors and solid-state imaging devices have limited dynamic range, particularly on the low illumination side, which hinders their effectiveness in various applications requiring sensitivity across a wide range of light intensities, including medical, pharmaceutical, and security markets.
Innovation Solution
The development of an optical sensor with a wide dynamic range, utilizing a light-receiving element, floating diffusion capacitor, lateral overflow integration capacitor, and non-LDD/MOS transistors with reduced impurity concentration, enabling single-photon detection and high sensitivity across a broad optical wavelength band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional optical sensor structures are used, then manufacturing is easier, but dynamic range is limited particularly on the low illumination side
Solution Approach 1:
The optical sensor is divided into multiple pixel types within the same pixel array: first pixels with a first photoelectric conversion element for high illumination detection, and second pixels with a second photoelectric conversion element for low illumination detection. This segmentation allows each pixel type to be optimized for its specific illumination range, achieving wide dynamic range coverage while maintaining manageable device complexity through modular architecture.
Solution Approach 2:
Different regions of the pixel array are assigned different photoelectric conversion elements with locally optimized characteristics. The first pixels use photoelectric conversion elements optimized for high illumination levels, while the second pixels use elements optimized for low illumination levels. This local quality differentiation enables the sensor to maintain high performance across the entire dynamic range without requiring a completely complex redesign of the entire device.
2Illumination intensity
If the dynamic range is widened to high illumination side, then high light detection is improved, but low illumination detection remains conventional
Solution Approach 1:
The pixel array is segmented into first pixels for high illumination detection and second pixels for low illumination detection. Each segment uses photoelectric conversion elements with characteristics optimized for its specific illumination range, allowing simultaneous improvement of both high illumination detection capability and low illumination detection precision without compromise.
Solution Approach 2:
The patent creates multiple copies of pixel structures with different photoelectric conversion elements within the same pixel array. By copying the pixel architecture but varying the photoelectric conversion element characteristics between first pixels and second pixels, the sensor achieves both high illumination and low illumination optimization through replicated but differentiated structures.
3Measurement precision
If single photon detection is achieved, then sensitivity is dramatically improved, but saturation performance at high illumination may be compromised
Solution Approach 1:
The sensor segments the pixel array into first pixels optimized for single-photon detection with high sensitivity and second pixels optimized for high saturation performance at high illumination levels. This segmentation allows each pixel type to operate at its optimal performance point without compromising the other, achieving both ultra-low light sensitivity and high light saturation capability across the same sensor device.
Solution Approach 2:
Different local regions of the pixel array are assigned different photoelectric conversion element characteristics: first pixels have elements optimized for maximum sensitivity to detect single photons, while second pixels have elements optimized for high saturation performance at high illumination levels. This local quality differentiation enables simultaneous achievement of both extreme sensitivity and high saturation performance.
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 solution provides an optical sensor with enhanced sensitivity, speed, and wide dynamic range, enabling effective detection from single-photon to high illumination levels, contributing to improved industry development and societal safety.
Implementation Method 1
a light-receiving element, storage capacitors that store a charge, and a transfer switch for transferring to the storage capacitors a charge generated by light input to the light-receiving element
Data Source
AI summary
One problem addressed by the present invention is to provide an optical sensor, a solid-state imaging device, and methods for reading the signals therefrom, which contribute greatly to the development of industry and the realization of a safer and more secure society. One solution according to the present invention is an optical sensor having a light-receiving element, storage capacitors that store a charge, and a transfer switch for transferring to the storage capacitors a charge generated by light input to the light-receiving element, wherein the storage capacitors are a floating diffusion capacitor and a lateral overflow integration capacitor, and the transfer switch is a non-LDD/MOS transistor, that is, a non-LDD/MOS transistor for which the impurity concentration of the drain region is reduced by 50%.