Photoelectric Conversion Layer Stack Color Imaging Device
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Solution Overview
Problem
Conventional color solid-state imaging devices face challenges in achieving high image quality, especially in dark scenes, due to low light utilization efficiency and sensitivity, and require complex manufacturing processes and costly production yields.
Innovation Solution
A hybrid photoelectric conversion layer stack type color solid-state imaging device with a semiconductor substrate and unit pixels arranged in a two-dimensional array, featuring signal memory means and row-direction scanning control for efficient signal processing, including correlation double sampling and sample-and-hold circuits, to enhance signal reading and output processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If color filters are arranged in mosaic form on photoelectric conversion pixels, then color signals can be obtained for each pixel, but light utilization efficiency and sensitivity are reduced because 2/3 of incident light is absorbed by the color filters
Solution Approach 1:
The photoelectric conversion function is segmented between the photoelectric conversion layer (detecting all colors) and the color filters (separating color signals). This allows the photoelectric conversion layer to utilize all incident light while the color filters provide spectral separation, resolving the contradiction between light utilization and color accuracy.
Solution Approach 2:
The patent introduces an intermediate processing stage where signal reading circuits perform correlation double sampling and color separation calculations. This intermediary processing enables the system to use the photoelectric conversion layer's full-spectrum detection capability while reconstructing accurate color signals through computational methods.
2Loss of energy
If three photoelectric conversion layers are laminated on the semiconductor substrate, then light utilization efficiency approaches 100% and high-resolution images are obtained, but manufacturing complexity increases and production yields decrease
Solution Approach 1:
The patent extracts the color separation function from the photoelectric conversion structure itself and relocates it to the signal processing domain. Instead of using multiple physical photoelectric conversion layers with different spectral responses, a single photoelectric conversion layer is used with computational color separation, thereby simplifying manufacturing while maintaining high light utilization efficiency.
Solution Approach 2:
The patent replaces the mechanical/physical approach of using multiple stacked photoelectric conversion layers with an electronic/computational approach using correlation double sampling and signal processing. This substitution maintains the optical performance benefits while eliminating the manufacturing complexity of aligning and fabricating multiple layers.
3Measurement precision
If triple wells photodiodes are used to detect different wavelengths at different depths, then spectral separation is achieved, but sufficient spectral separation is not obtained and heavy computation load is required for addition/subtraction processing
Solution Approach 1:
The patent performs preliminary spectral separation during the photoelectric conversion process itself, where the photoelectric conversion layer converts different wavelengths into distinguishable signal characteristics. The subsequent correlation double sampling then efficiently extracts color information with reduced computation compared to post-processing addition/subtraction methods.
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
The device achieves high image quality with improved sensitivity and reduced noise, enabling high-resolution images even in low-light conditions without the need for flash, while simplifying the manufacturing process and reducing costs.
Implementation Method 1
a photoelectric conversion layer (one layer) that is sensitive to green (G) light is laid on a semiconductor substrate
Implementation Method 2
blue light and red light that has passed through the photoelectric conversion layer is detected by two sets of photodiodes
Data Source
AI summary
A color solid state imaging device as defined herein, which includes an output signal processing section including: signal memory means provided for respective columns of the unit pixels, for holding signals read-out from the pixels of the same color of the same unit pixel row, respectively; and row-direction scanning control means for switching between an all pixels reading operation in which the signals held by the respective signal memory means are read out individually and output to the outside and a sum reading operation in which among the signals held by the respective signal memory means signals held by signal memory means corresponding to adjoining unit pixels are read out simultaneously and output to the outside.