Eccentric Microlens Overlap for Phase Detection Sensitivity
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Solution Overview
Problem
Existing solid state imaging devices with phase difference AF methods face reduced sensitivity due to the need for eccentric or shifted microlenses, which increases material and processing costs and complexity.
Innovation Solution
The arrangement of phase difference detection pixels with eccentric microlenses that overlap adjacent pixels, allowing for larger microlens areas without the need for additional pupil forming lenses, thereby maintaining sensitivity without cost increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical axis of the microlens is shifted from the center of the photoelectric converter to improve sensitivity, then the sensitivity of phase difference detection pixels is improved, but the microlens area must be reduced which worsens the sensitivity
Solution Approach 1:
The patent merges the microlens area that would normally be lost due to eccentricity with the adjacent pixel's microlens area. By allowing the microlens to overlap into the adjacent pixel region, the effective light-gathering area is maintained while still achieving the angular selectivity needed for phase difference detection. This resolves the contradiction by combining spatial resources from neighboring pixels.
2Measurement precision
If a pupil forming microlens is added to cover two phase difference detection pixels, then the sensitivity is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
Each microlens serves multiple functions: it provides angular selectivity for phase difference detection, maintains adequate light-gathering area, and its eccentric positioning enables it to share functionality with adjacent pixels. The microlens acts as both a focusing element and a spatial filter, while its overlapping configuration with adjacent pixels creates a shared optical path that reduces the need for additional pupil-forming elements.
Solution Approach 2:
Instead of adding separate pupil-forming microlenses for each pixel, the patent combines the functional requirements by allowing each pixel's microlens to extend into the adjacent pixel's region. This merging approach achieves the pupil-forming effect through the eccentric positioning and overlapping of existing microlenses, rather than adding separate components.
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 of phase difference detection pixels while avoiding the need for additional processing steps and materials, thus maintaining cost-effectiveness.
Implementation Method 1
The microlens condenses the light onto the photoelectric converter
Implementation Method 2
The photoelectric converter photoelectrically converts incident light into charge and accumulates the charge
Data Source
AI summary
A CCD image sensor, being a solid state imaging device, has four types of pixels, first to fourth pixels. The first to fourth pixels are arranged in a predetermined pattern. Each of the pixels has a PD and a microlens. Each of the microlens is arranged with its optical axis center eccentric or shifted in a predetermined direction from a center of a light receiving surface of the PD. A part of the microlens overlaps one or more adjacent pixels.