Auto Focus Calibration Error Detection Using Collimator Lens
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Solution Overview
Problem
Existing auto focus calibration methods in camera modules are prone to errors due to lens deviations and erroneous operations, leading to incorrect storage of focus codes, which can result in failed infinity focus captures.
Innovation Solution
A system and method that uses a collimator lens to measure Display Field of View (DFOV) values before and after interposition between a resolution chart and a camera module, with a controller determining if the difference exceeds a threshold to detect and prevent auto focus calibration errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a collimator lens is used to measure infinity autofocus calibration, then the focus position can be determined, but errors occur due to lens deviation and erroneous operation leading to incorrect calibration codes
Solution Approach 1:
The patent performs preliminary actions by measuring DFOV values before and after collimator lens interposition, and detecting potential errors before the actual autofocus calibration is executed. This prevents incorrect calibration codes from being stored in the first place, rather than detecting them after the fact.
Solution Approach 2:
The system implements feedback by measuring DFOV values, calculating their difference, and using this information to determine whether to proceed with autofocus calibration. The feedback loop compares the measured difference against a threshold to decide whether the calibration should be performed, preventing error propagation.
2Productivity
If autofocus calibration is performed without error detection, then the process is simple and fast, but incorrect calibration codes are stored leading to failed infinity focus captures
Solution Approach 1:
The error detection process is performed as a preliminary action before the actual autofocus calibration. By measuring DFOV values and detecting potential errors in advance, the system prevents incorrect calibration without requiring rework or additional calibration steps, thus maintaining productivity while improving reliability.
3Reliability
If DFOV measurement and comparison is performed before autofocus calibration, then calibration errors are detected and prevented, but the process complexity increases
Solution Approach 1:
The system performs self-service by using its own existing DFOV measurement capability to detect calibration errors. The same controller and measurement units used for normal operation are leveraged to perform the error detection, eliminating the need for separate dedicated error detection hardware or complex additional systems.
Data Source
AI summary
Provided is a method and a system for detecting an error focus calibration, wherein a first DFOV value is measured in a state before the collimator lens is interposed between the resolution chart and the camera module, and a second DFOV value is measured in a state after the collimator lens is interposed between the resolution chart and the camera module, a determination is made whether a value obtained by subtracting the second DFOV value from the first DFOV value is smaller than a threshold value, and detecting as an error of auto calibration, in a case the subtracted value is greater than the threshold value.