Discrete Automatic Focusing Using Curvature Variable Diffraction Device
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Solution Overview
Problem
Existing camera module focusing methods are inefficient and slow, particularly in miniaturized devices like cellular phones and digital cameras, as they rely on continuous focusing methods that are not suitable for fast and complex focusing requirements.
Innovation Solution
A discrete automatic focusing method using a curvature variable reflective type diffraction device, which moves the focus to specific positions, compares focusing values, and adjusts the curvature to optimize focusing speed and accuracy, reducing the number of operations required for focusing and error correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a continuous automatic focusing method is used to control focus distance by changing the curvature of a diffraction device, then focusing can be performed over the entire focus variable range, but the focusing operation becomes slow and complex
Solution Approach 1:
The patent divides the continuous focusing range into discrete positions (e.g., first position, second position, third position). Instead of continuously adjusting the diffraction device curvature across the entire range, the system only needs to move between these specific discrete positions, significantly reducing the time and complexity of focusing operations while maintaining adequate focusing accuracy for each segment.
2Measurement precision
If the position of a lens is moved to control focus distance using traditional methods, then focusing can be achieved, but the camera module size and volume increase
Solution Approach 1:
The patent replaces the traditional mechanical lens movement system with an optical-based solution using a curvature variable diffraction device. Instead of physically moving the lens to change focus distance, the system changes the curvature of the diffraction device to achieve focusing, eliminating the need for large mechanical actuation space and reducing overall camera module volume.
3Adaptability or versatility
If a related art focusing method is used that works regardless of focusing position, then the method is universally applicable, but it cannot meet complicated and fast response requirements
Solution Approach 1:
The patent implements different focusing strategies for different positions within the focusing range. Rather than using a single universal focusing method, the system applies discrete position-based control where specific focusing operations are performed based on the current position and target position, enabling faster response times tailored to each local region of the focusing range.
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 method enables faster and more efficient focusing over an entire image frame, reducing the time required for focusing and correcting focusing errors, while maintaining a small operation load and improving focusing speed compared to traditional methods.
Implementation Method 1
a method of fixing the position of a lens and controlling the curvature of a reflective type curvature variable diffraction device has been proposed recently
Data Source
AI summary
Provided are a discrete AF control method and an error correcting method of a camera module using a diffraction device. In the method, a focus is moved to a (the number of all positions/m)-th position, and a focusing value at a start position is compared with that at the (the number of all positions/m)-th position. A focus is moved by two positions in a first direction according to the comparison result. If a position having a maximum focusing value is passed, a focus is moved by one position in a direction opposite to the first direction and a location (corresponding to an n-th position) is stored. Focusing values of the n-th position, an (n−1)-th position, and an (n−2)-th position are compared with one another to determine a maximum focus location, m being an integer equal to or greater than 2.