Camera Module Calibration Using Gravity Reference
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Solution Overview
Problem
Existing camera modules face challenges in calibrating angular velocity sensors without applying vibration, especially when the sensor and camera module are not integrated, leading to difficulties in correcting hand blur caused by angular motion.
Innovation Solution
A calibration method that detects deviation angles between the blur detection element and gravity, allowing for high-precision hand blur correction by using gravity as an intermediary to align the camera module's pixel axis with the sensor's detection axis without requiring vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If vibration is applied to calibrate the angular velocity sensor, then the calibration accuracy is improved, but the calibration process becomes time-consuming and cumbersome
Solution Approach 1:
The patent replaces the mechanical vibration-based calibration method with a gravity-based calibration method. Instead of applying physical vibration to the camera module to calibrate the angular velocity sensor, the system uses the constant gravitational force as a reference to determine the relationship between the sensor's detection axis and the camera module's pixel axis. This substitution eliminates the need for complex vibration application equipment and significantly reduces calibration time while maintaining accuracy.
Solution Approach 2:
The calibration method utilizes the Earth's gravity field, which is always present and requires no external activation, to perform self-calibration of the angular velocity sensor. The camera module itself, through its imaging element capturing images at different orientations, generates the necessary data for calibration without requiring external vibration sources or complex test equipment.
2Adaptability or versatility
If the sensor and camera module are separately mounted, then the device assembly flexibility is improved, but the calibration process becomes more difficult
Solution Approach 1:
The patent introduces the gravity direction as an intermediary reference frame that connects the separately mounted sensor and camera module. By capturing images of a calibration chart at multiple orientations and using gravity as the common reference, the system can determine the rotational relationship between the sensor's detection axis and the camera module's pixel axis even when they are independently mounted. This intermediary approach simplifies the calibration process for separately mounted components.
Solution Approach 2:
The calibration process transitions from a single-orientation measurement to a multi-orientation measurement in three-dimensional space. By capturing images at different rotational angles around the optical axis and combining this with gravity direction information, the system can resolve the spatial relationship between the sensor and camera module axes, making calibration feasible for separately mounted 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
Enables precise calibration and correction of hand blur in camera modules, even when the sensor and camera are not integrated, improving image stabilization without the need for vibration-based calibration processes.
Implementation Method 1
a gravity detection element configured to detect a direction of gravity acting on the imaging device
Implementation Method 2
Each blur amount is detected as an angular velocity signal by a gyro sensor
Data Source
AI summary
A calibration method for an imaging device including a camera module including an imaging element and a lens installed on a path of light incident on the imaging element; a blur detection element configured to detect an amount of blur acting on the imaging device; and a gravity detection element configured to determine a direction of gravity acting on the imaging device. The calibration method includes: detecting a first angle corresponding to a deviation of a direction of a coordinate axis of the blur detection element with respect to the direction of gravity; detecting a second angle corresponding to a deviation of a direction of the camera module with respect to the direction of gravity; and acquiring a parameter for correcting a detection signal of the blur detection element based on the first angle and the second angle.