Imaging Element Charge Retaining Unit Positioning
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Solution Overview
Problem
In imaging elements, particularly those using phase-difference detecting pixels, it is challenging to increase the width of the light receiving area of the photoelectric conversion unit without compromising pixel performance due to the adjacent placement of the electric charge retaining unit, which affects oblique incidence characteristics and sensitivity.
Innovation Solution
The imaging element is designed with a configuration where the electric charge retaining unit is positioned in an area excluding the trajectory of the photoelectric conversion unit's movement, allowing for increased width of the photoelectric conversion unit and improved light receiving area, enhancing pixel performance by separating the charge transfer unit and retaining unit within the semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electric charge retaining unit is placed adjacent to the photoelectric conversion unit in the phase difference detection direction, then the pixel structure is compact and manufacturable, but the width of the light receiving area is reduced and pixel performance deteriorates
Solution Approach 1:
The patent repositions the electric charge retaining unit from an adjacent location in the phase difference detection direction to a location in a different dimension (perpendicular direction or diagonal direction). This spatial reconfiguration allows the light receiving area to expand in the phase difference detection direction without compromising the compact pixel structure, thereby resolving the contradiction between manufacturability and detection precision.
2Measurement precision
If the width of the light receiving area of the photoelectric conversion unit is increased, then pixel sensitivity and oblique incidence characteristics improve, but the area available for other pixel components is reduced
Solution Approach 1:
By relocating the electric charge retaining unit to a different spatial dimension (not adjacent in the phase difference detection direction), the patent enables the photoelectric conversion unit to occupy a larger area in the critical detection direction while maintaining adequate space for all pixel components through three-dimensional spatial optimization.
3Measurement precision
If the width of the light receiving area approaches the wavelength of light, then the photoelectric conversion efficiency increases, but light incidence becomes difficult and pixel performance deteriorates
Solution Approach 1:
The patent positions the electric charge retaining unit in a location that does not block the light path in the phase difference detection direction, allowing the light receiving area to achieve optimal width for photoelectric conversion efficiency while maintaining proper light incidence characteristics by avoiding obstruction in the critical detection dimension.
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 sensitivity and oblique incidence characteristics of phase-difference detecting pixels, improving overall pixel performance and enabling high-accurate focusing control in imaging devices.
Implementation Method 1
a photoelectric conversion unit which is formed within a semiconductor substrate, receives one of a pair of luminous flux passed through different portions arranged in one direction of a pupil area of the imaging optical system, and accumulates electric charges corresponding to a light reception amount
Data Source
AI summary
An imaging element that images a subject through an imaging optical system, and includes a plurality of pairs each including a photoelectric conversion unit which is formed within a semiconductor substrate, receives one of a pair of luminous flux passed through different portions arranged in one direction of a pupil area of the imaging optical system, and accumulates electric charges corresponding to a light reception amount, and a photoelectric conversion unit which is formed within the semiconductor substrate, receives the other one of the pair of luminous flux, and accumulates electric charges corresponding to a light reception amount, each of pixels including the photoelectric conversion units constituting the pair includes an electric charge retaining unit as defined herein, and when being viewed in a direction perpendicular to the semiconductor substrate, the electric charge retaining unit included in the pixel is disposed in an area as defined herein.