Photoelectric Conversion Pixel Charge Transfer Synchronization
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Solution Overview
Problem
Existing photoelectric conversion apparatuses experience variation in image signals due to differences in transfer characteristics and noise levels caused by varying readout methods, leading to inconsistencies in focus detection and image acquisition.
Innovation Solution
A photoelectric conversion apparatus with first and second pixels, each equipped with photoelectric conversion elements, transfer gates, and an amplifying unit, performs specific readout operations to retain charges in the input node, synchronizing the conditions of transfer operations between different readout methods, thereby reducing signal variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If different readout methods are used for focus detection and image acquisition, then readout time is reduced and functionality is improved, but variation between image signals increases due to differences in transfer characteristics and noise levels
Solution Approach 1:
The patent applies preliminary action by performing a charge transfer operation in advance for pixels that will only output image signals. Specifically, the first transfer gate is activated to transfer charge from the first photoelectric conversion element to the input node before the second transfer gate transfers charge from the second photoelectric conversion element. This preliminary charge transfer ensures that the input node experiences the same charge transfer conditions regardless of whether the pixel is in focus detection mode or image-only mode, thereby reducing signal variation while maintaining different readout methods for different functions
2Productivity
If charge transfer operations are performed differently for focus detection pixels and image-only pixels, then readout efficiency is improved, but transfer characteristic variation increases
Solution Approach 1:
The patent performs a preliminary charge transfer operation using the first transfer gate before the main charge transfer operation using the second transfer gate. This preliminary action ensures that the input node is pre-conditioned with charge from the first photoelectric conversion element, so that when the second transfer gate operates, the transfer characteristics are consistent with those experienced during focus detection operations. This maintains transfer characteristic consistency while allowing different readout efficiencies for different pixel types
3Loss of time
If only image signals are read out from certain pixels, then readout time is reduced, but noise levels and signal variation increase
Solution Approach 1:
The patent performs a preliminary charge transfer operation from the first photoelectric conversion element to the input node before reading out the image signal. This preliminary action serves two purposes: it maintains the transfer characteristics consistent with focus detection operations, and it allows the system to proceed directly to image signal readout without performing additional charge transfer operations that would increase readout time. The noise level is controlled by ensuring consistent transfer conditions while minimizing the number of operations
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 reduces variation between image signals acquired by different readout methods, enhancing the consistency and quality of focus detection and image information.
Implementation Method 1
a first photoelectric conversion element, a second photoelectric conversion element... a microlens configured to condense incident light onto the first photoelectric conversion element and the second photoelectric conversion element
Data Source
AI summary
An apparatus including pixels, each having first and second photoelectric conversion elements, an amplifying unit, first and second transfer gates, and a microlens, performs, in one pixel, a first operation involving turning on the first transfer gate, outputting a signal based on charge generated in the first photoelectric conversion element, turning on the first and second transfer gates while retaining the charge generated and transferred to an input node, and outputting a signal based on charges generated in the first and second photoelectric conversion elements, and, in another pixel, a second operation involving turning on the first transfer gate, not outputting a signal based on charge generated in the first photoelectric conversion element, turning on the first and second transfer gates while retaining the charge generated and transferred to the input node, and outputting a signal based on charges generated in the first and second photoelectric conversion elements.