2D CMOS Autofocus Sensor Adaptive Pixel Selection
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Solution Overview
Problem
Conventional phase detection autofocus systems face challenges such as precision degradation due to temperature changes, poor performance in low light conditions, and limited flexibility in handling structures oriented at angles like 45 degrees, as they rely on discrete sensors and separate phase-detection modules.
Innovation Solution
A phase detection autofocus system utilizing a single high-resolution 2D CMOS image sensor with a continuous array of pixels, allowing for dynamic selection of pixels and adaptive correlation analysis to generate focus measurement signals, which compensates for misalignment and improves precision and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If discrete linear sensors are used for phase detection autofocus, then the system can provide focus measurement for horizontal and vertical structures, but precision is degraded for oblique structures oriented at angles like 45 degrees
Solution Approach 1:
The patent transitions from one-dimensional linear sensor arrays to two-dimensional area sensors, enabling the system to capture and analyze phase information from luminous bundles in multiple directions simultaneously. This dimensional expansion allows accurate focus measurement for structures of any orientation, including oblique structures at 45 degrees, by providing sufficient sampling points across the entire sensor surface rather than being constrained to horizontal and vertical lines only.
Solution Approach 2:
The area sensors serve multiple functions: they detect phase information for horizontal structures, vertical structures, and oblique structures of any orientation simultaneously. This universal capability replaces the need for separate sensor configurations for different structure types, making the autofocus system adaptable to any subject geometry without requiring mechanical adjustments or specialized sensor orientations.
2Reliability
If separate phase-detection AF modules are used in DSLR cameras, then phase detection can be provided in optical viewfinder mode, but the system complexity and physical size increase
Solution Approach 1:
The patent combines the phase detection function with the existing image sensor, eliminating the need for separate phase-detection AF modules. The same area sensor used for capturing images also performs phase detection by analyzing the relative positions of luminous bundles, thereby integrating two functions into a single component and reducing overall system complexity.
Solution Approach 2:
The image sensor serves dual purposes: it captures the final image and simultaneously performs phase detection autofocus by analyzing the phase information embedded in the luminous bundles. This multi-functional approach eliminates redundant components and simplifies the camera system architecture while maintaining reliable phase detection capability.
3Measurement precision
If conventional phase detection autofocus systems are used, then focus measurement can be obtained, but precision degrades with temperature changes and mechanical misalignment
Solution Approach 1:
The patent implements a feedback mechanism where the system continuously monitors the relative positions of luminous bundles on the area sensor and automatically adjusts focus based on this information. This closed-loop approach compensates for temperature-induced drift and mechanical misalignment by constantly measuring and correcting focus errors, thereby maintaining stable precision under varying environmental conditions.
Solution Approach 2:
The system dynamically adjusts focus parameters based on real-time phase measurements from the area sensor. By continuously monitoring positional changes of luminous bundles and responding with appropriate focus adjustments, the system compensates for environmental variations and mechanical instabilities, maintaining measurement precision despite changes in temperature or alignment.
4Adaptability or versatility
If multiple discrete sensors are used for phase detection, then focus points can be distributed across the frame, but the device size and power consumption increase
Solution Approach 1:
The patent merges multiple discrete sensor functions into a single area sensor that provides phase detection across the entire sensor surface. This unified approach enables distributed focus points throughout the frame without requiring multiple separate sensor modules, thereby reducing overall weight and complexity while maintaining the capability to focus on multiple regions simultaneously.
Solution Approach 2:
The area sensor provides universal phase detection coverage across the entire sensor surface, enabling the system to establish focus points at any location within the frame. This single sensor performs the function that would otherwise require multiple discrete sensors, reducing weight and power consumption while maintaining full-frame focus flexibility.
5Manufacturing precision
If high-precision calibration systems are implemented during manufacturing, then initial autofocus accuracy can be achieved, but the system remains sensitive to temperature changes and precision degrades over time
Solution Approach 1:
The patent implements continuous feedback-based autofocus using area sensors that monitor phase information in real-time. This ongoing measurement and adjustment process compensates for drift caused by temperature changes and mechanical variations, maintaining reliable focus accuracy over time without depending solely on initial manufacturing calibration. The system self-corrects for environmental effects through continuous phase measurement and lens position adjustment.
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 enhances autofocus precision and reliability by minimizing physical size, power consumption, and complexity, while providing robust autofocusing in various light conditions and orientations, and allows for automatic calibration without mechanical adjustments.
Implementation Method 1
pairs of luminous bundles from the taking lens are focused, each by its own microlens
Implementation Method 2
a single high resolution, 2D CMOS image sensor with a single continuous, 2D array of pixels
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
The invention relates to a phase detection autofocus system using a single two-dimensional (2D) image sensor (16) as an autofocus sensor (14). This allows for a number of novel functionalities such as calibration by adaptive selection of pixels for the autofocus collection zone, dynamically optimization of the collection zone for various scene and lightning conditions, as well as the use of 2D phase signals in the cross-correlation. This freedom in selecting which pixels to use gives rise to an equivalent freedom for the focus points presented to the user, which can be created, moved and scaled according to the conditions and the scene.