Solid-State Imaging Device with Light Shielding Films for Phase Difference Detection
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Solution Overview
Problem
Existing solid-state imaging devices with global shutter and phase difference AF functions face challenges in improving phase difference detection precision without deteriorating image resolution, as they often reduce the light-receiving area of phase difference detection pixels or halve the number of effective pixels.
Innovation Solution
A solid-state imaging device with a pixel array unit including imaging pixels and phase difference detection pixels, where the charge accumulation unit is shielded from light in imaging pixels and partially unshielded in phase difference detection pixels, allowing for simultaneous charge accumulation and reading, and utilizing a driving control unit to optimize the sensitivity and accumulation time of phase difference detection pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the charge accumulation unit is shielded from light in phase difference detection pixels, then the precision of phase difference detection is improved, but the light-receiving area is reduced and sensitivity is lowered
Solution Approach 1:
The pixel array is segmented into imaging pixels with shielded charge accumulation units and phase difference detection pixels with unshielded charge accumulation units. This segmentation allows different functional requirements to be met simultaneously: imaging pixels achieve precise charge retention while phase difference detection pixels maintain light-receiving capability for sensitivity.
Solution Approach 2:
Different light-shielding configurations are applied to different regions of the pixel array. Imaging pixels have fully shielded charge accumulation units for precise charge retention, while phase difference detection pixels have unshielded charge accumulation units to maintain light-receiving area and sensitivity. This local differentiation resolves the contradiction between precision and sensitivity.
2Adaptability or versatility
If the number of effective pixels is reduced by half to form sets of imaging pixels and phase difference detection pixels, then the phase difference AF function is implemented, but the resolution of the output image is lowered
Solution Approach 1:
Each pixel in the array is designed to function as both an imaging pixel and a phase difference detection pixel depending on the operational mode. The pixel array can operate in full-resolution imaging mode or phase difference detection mode, providing multi-functionality without sacrificing resolution or detection capability.
Solution Approach 2:
The pixel array dynamically switches between imaging mode and phase difference detection mode through control signals. This dynamic operation allows the system to adapt to different functional requirements without physical reconfiguration, maintaining both high resolution and phase difference detection capability.
3Adaptability or versatility
If one phase difference detection pixel includes two sets of photoelectric conversion unit and charge retention unit, then the global shutter function is implemented, but the light-receiving area is reduced and sensitivity is lowered
Solution Approach 1:
The phase difference detection pixel merges the photoelectric conversion unit and charge accumulation unit into a single integrated structure without light shielding. This merging maintains the light-receiving area while enabling both global shutter operation and phase difference detection through coordinated control of charge transfer and accumulation.
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 approach enhances phase difference detection precision while maintaining image resolution by ensuring the phase difference detection pixels are not light-shielded, thus not reducing their effective area and the overall number of pixels, thereby improving the device's performance in both global shutter and phase difference AF functions.
Implementation Method 1
a light-shielding film that shields a region in the pixel array
Implementation Method 2
a photoelectric conversion unit, and a charge accumulation unit
Data Source
AI summary
The present technology relates to a solid-state imaging device and a driving method thereof, and an electronic apparatus that make it possible to improve the precision of phase difference detection while suppressing deterioration of resolution in a solid-state imaging device having a global shutter function and a phase difference AF function. Provided is a solid-state imaging device including: a pixel array unit including, as pixels including an on-chip lens, a photoelectric conversion unit, and a charge accumulation unit, imaging pixels for generating a captured image and phase difference detection pixels for performing phase difference detection arrayed therein; and a driving control unit configured to control driving of the pixels. The imaging pixel is formed with the charge accumulation unit shielded from light. The phase difference detection pixel is formed in a manner that at least part of at least one of the photoelectric conversion unit and the charge accumulation unit refrains from being shielded from light. The present technology can be applied to, for example, a CMOS image sensor.