Split-Electrode Imaging Pixel for More Accurate Phase-Detection Autofocus
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Solution Overview
Problem
The existing solid-state imaging devices face challenges in achieving high auto-focusing accuracy due to low light sensitivity caused by light passing through the photoelectric conversion film rather than being absorbed, leading to weak incident light intensity.
Innovation Solution
A solid-state imaging device with a pixel structure where the photoelectric conversion film is interposed by upper and lower electrodes, with the upper electrode divided into two parts, allowing different voltages to be applied, enhancing light absorption and sensitivity for phase difference signal acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light passes through the photoelectric conversion film for phase difference detection, then the structure is simple and easy to manufacture, but the light intensity is weak and sensitivity is low
Solution Approach 1:
The pixel is divided into two distinct regions: a first photoelectric conversion region with a first photodiode for image signal generation, and a second photoelectric conversion region with a second photodiode for phase difference signal generation. This segmentation allows each region to be optimized for its specific function, with the second region specifically designed to capture transmitted light for focus detection while the first region captures absorbed light for imaging.
Solution Approach 2:
Different photoelectric conversion portions are assigned different functions within the same pixel structure. The first photodiode is optimized for image signal detection while the second photodiode is optimized for phase difference detection. This local differentiation allows the system to simultaneously achieve high-quality imaging and accurate auto-focusing without compromising either function.
2Device complexity
If a single photodiode structure is used, then the device complexity is low, but the ability to simultaneously achieve image generation and phase difference detection is insufficient
Solution Approach 1:
The single pixel is segmented into two functional photoelectric conversion regions, each with its own photodiode. The first photodiode generates image signals while the second photodiode generates phase difference signals. This segmentation enables one pixel to perform multiple functions that would otherwise require separate structures.
Solution Approach 2:
The pixel structure is designed to serve multiple purposes simultaneously. By incorporating both a first photodiode for imaging and a second photodiode for focus detection within the same pixel, the structure achieves multi-functionality, allowing the imaging device to capture images and perform auto-focusing using the same photoelectric conversion element.
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 improves auto-focusing accuracy by increasing light absorption and sensitivity, enabling more precise focus detection using phase difference signals.
Implementation Method 1
a photoelectric conversion portion configured with a photoelectric conversion film (52) interposed by a lower electrode (53a) and an upper electrode (54a)
Data Source
AI summary
The present disclosure relates to a solid-state imaging device, a method for driving the solid-state imaging device, and an electronic device capable of improving auto-focusing accuracy by using a phase difference signal obtained by using a photoelectric conversion film. The solid-state imaging device includes a pixel including a photoelectric conversion portion having a structure where a photoelectric conversion film is interposed by an upper electrode on the photoelectric conversion film and a lower electrode under the photoelectric conversion film. The upper electrode is divided into a first upper electrode and a second upper electrode. The present disclosure can be applied to, for example, a solid-state imaging device or the like.