Image Pickup Power Supply Line Configuration for Focus Detection
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Solution Overview
Problem
The accuracy of focus detection in image pickup apparatuses is degraded due to differences in the characteristics of transistors that read signals from photoelectric conversion units, particularly when these units are connected to different power supply lines, leading to variations in signal output despite equal light incidence.
Innovation Solution
The image pickup apparatus arranges photoelectric conversion units and their corresponding transistors on the same power supply line to minimize differences in transistor characteristics, using a power supply line configuration with conductive members extending in different directions to ensure uniform power supply, thereby reducing noise and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If photoelectric conversion units are connected to different power supply lines, then the device complexity is reduced, but the measurement precision of focus detection is degraded due to transistor characteristic variations
Solution Approach 1:
The patent merges transistors reading signals from the same color photoelectric conversion units onto the same power supply line, ensuring they receive identical power supply voltage. This combination eliminates characteristic variations caused by different power supply voltages, thereby improving focus detection accuracy while maintaining a relatively simple power supply structure.
Solution Approach 2:
The patent applies different power supply line configurations to different regions: transistors for the same color are connected to the same power supply line (first conductive member), while transistors for different colors can be connected to different power supply lines (second conductive member). This localized quality approach optimizes focus detection accuracy where needed while maintaining overall device simplicity.
2Manufacturing precision
If the number of pixels is increased to capture high-resolution images, then the image quality is improved, but the aperture ratio of photoelectric conversion units is reduced
Solution Approach 1:
The patent merges multiple transistors onto shared power supply lines, reducing the total number of power supply connections needed. This allows more space to be allocated to photoelectric conversion units, effectively increasing their aperture ratio even as pixel density increases, thereby maintaining energy efficiency while achieving high-resolution imaging.
3Ease of operation
If transistors are disposed for each photoelectric conversion unit, then the signal reading capability is improved, but the device complexity increases due to multiple transistors and power supply lines
Solution Approach 1:
The patent combines multiple transistors onto the same power supply line structure, particularly for transistors reading signals from the same color photoelectric conversion units. This merging reduces the total number of power supply connections while maintaining full signal reading capability for each photoelectric conversion unit, thereby reducing device complexity without sacrificing operational capability.
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 enhances the accuracy of focus detection and image quality by reducing variations in signal output from transistors for the same color photoelectric conversion units, minimizing noise, and maintaining consistent power supply across adjacent transistors.
Implementation Method 1
a first photoelectric conversion unit PD3A and a second photoelectric conversion unit PD3B that receive incident light in a first wavelength range and a third photoelectric conversion unit PD4A that receive incident light in a second wavelength range
Data Source
AI summary
An image pickup apparatus according to one or more embodiments includes a power line and first through fourth photodiodes. The first, second, and third photodiodes are arranged along a first direction so that the first photodiode is adjacent to the second photodiode, and the second photodiode is adjacent to the third photodiode. The power line includes a first conductor disposed along the first direction and a second conductor disposed along a second direction that intersects the first direction. The second conductor is disposed on a region between the second and third photodiodes. First and second transistors corresponding to the first and second photodiode, respectively, are connected to the power line. The fourth photodiode is disposed adjacent to the second photodiode in the second direction. A third transistor corresponding to the fourth photodiode is connected to the power line.