Segmented PDAF Lens Layout for High-Illuminance Autofocus
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Solution Overview
Problem
Existing image sensing devices face challenges in performing phase-difference detection autofocus (PDAF) effectively across a high-illuminance range, particularly in adjusting the sensitivity of phase-difference detection pixels to prevent saturation and maintain accurate autofocus functionality.
Innovation Solution
The image sensing device incorporates a pixel array with phase-difference detection pixels arranged in a (2×2) matrix, coupled with a first lens that directs light to these pixels. The first lens has a center thickness greater than that of the second lens, with a concave curvature toward the center, allowing for adjusted sensitivity and improved phase-difference detection capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional lens is used for phase-difference detection, then the structure is simple, but the detection sensitivity is insufficient and saturation occurs in high-illuminance conditions
Solution Approach 1:
The lens is divided into multiple portions (first, second, third portions) with different optical characteristics. Each portion directs light to specific phase-difference detection pixels, allowing differential sensitivity control across the detection array without requiring multiple separate lenses.
Solution Approach 2:
Different portions of the lens are designed with different curvatures and optical properties to provide locally optimized light control. The first portion has a specific curvature for directing light to first pixels, while the second portion has a different curvature for second pixels, enabling tailored sensitivity for different illuminance conditions.
2Reliability
If the lens directs light to all phase-difference detection pixels uniformly, then the structure is simple, but saturation occurs in high-illuminance conditions
Solution Approach 1:
The lens is segmented into distinct portions that selectively direct light to different groups of phase-difference detection pixels. This segmentation prevents any single pixel or small group from receiving excessive light in high-illuminance conditions, thereby preventing saturation while maintaining reliable autofocus operation.
Solution Approach 2:
The lens portions act as intermediaries that mediate between the incoming light and the phase-difference detection pixels. By controlling which pixels receive light from which portions, the system prevents direct uncontrolled light exposure that would cause saturation.
3Measurement precision
If the lens has high sensitivity for phase-difference detection, then autofocus accuracy is improved, but the device cannot handle high-illuminance conditions
Solution Approach 1:
Different portions of the lens have different optical qualities (curvatures, focal properties) tailored to specific detection needs. Some portions are optimized for high sensitivity in low-illuminance conditions, while the overall segmented structure ensures that no single portion over-exposes pixels in high-illuminance conditions, thus maintaining both accuracy and broad illuminance range.
Solution Approach 2:
The lens system dynamically adapts to different illuminance conditions through its segmented structure. In high-illuminance conditions, the segmentation naturally distributes light to prevent saturation. In low-illuminance conditions, the optical design maintains sufficient light gathering capability for accurate phase-difference detection.
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 enables the image sensing device to perform PDAF with enhanced sensitivity and accuracy across a wide illuminance range, preventing saturation of phase-difference detection pixels and ensuring reliable autofocus functionality.
Implementation Method 1
a first lens positioned to direct light to the plurality of phase-difference detection pixels and including a plurality of portions each corresponding to at least one of the phase-difference detection pixels
Implementation Method 2
a plurality of phase-difference detection pixels in the pixel array and structured to detect light from the object to generate a phase signal for measuring a distance between the image sensing device and the object
Data Source
AI summary
An image sensing device includes a pixel array including a plurality of image detection pixels structured to convert light incident onto the image detection pixels into pixel signals representing an image of an object, a plurality of phase-difference detection pixels in the pixel array structured to detect light from the object to generate a phase signal for measuring a distance between the image sensing device and the object, and a first lens positioned to direct light to the plurality of phase-difference detection pixels and including a plurality of portions each corresponding to at least one of the phase-difference detection pixels. A center of the first lens is located over a center of the plurality of phase-difference detection pixels, and each portion of the first lens extends from the center along a row or column direction between adjacent phase-difference detection pixels or along diagonal directions between the row and column directions.