Actuator Driver DC Component Correction for Image Shift
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Solution Overview
Problem
In camera modules with optical image stabilization, the accumulation of DC components during hand blur correction can lead to lens position offset, causing image shifts and user discomfort due to sudden changes, and may result in insufficient movable range for effective hand blur correction.
Innovation Solution
An imaging device with an actuator driver that forcibly changes the DC component of the imaging lens position, calculates the change amount from the drive signal or position detection signal, and shifts the effective pixel area to correct image shifts, allowing for seamless centering operations without user perception of image movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the position of the imaging lens is forcibly returned to the original predetermined position to correct DC component accumulation, then the lens position offset is corrected, but the image shifts suddenly causing user discomfort
Solution Approach 1:
The patent introduces an image shift correction mechanism that acts as an intermediary between the lens position adjustment and the final image output. When the lens position is forcibly changed to correct DC component accumulation, the system simultaneously applies a compensating shift to the image data to counteract the visual impact, thereby eliminating the harmful image shift effect while maintaining the corrective lens movement
Solution Approach 2:
The system changes the parameter of image data transformation by applying a pixel shift correction based on the lens movement amount. This parameter change in the image processing domain compensates for the physical lens movement, allowing the lens to be repositioned for DC correction without causing perceptible image shift to the user
2Object-affected harmful factors
If the centering operation is performed slowly to avoid user perception of image shift, then user comfort is maintained, but the movable range becomes insufficient for effective hand blur correction
Solution Approach 1:
The image shift correction mechanism serves as a mediator that decouples the speed of lens movement from the perceived image stability. This allows the lens to move quickly for efficient DC correction while the image processing simultaneously compensates to maintain visual stability, thus resolving the contradiction between correction speed and user comfort
3Measurement precision
If the position detection signal is used to determine lens position for feedback control, then precise feedback control is achieved, but the DC component accumulation causes continuous offset
Solution Approach 1:
The system extracts and removes the DC component from the position detection signal through a high-pass filter or differential processing. By separating the AC component (useful for feedback control) from the DC component (causing offset accumulation), the system maintains precise feedback control while eliminating the stability-degrading DC accumulation
Solution Approach 2:
The system implements a dual feedback mechanism: one feedback loop uses the AC component of the position detection signal for continuous hand blur correction, while another feedback mechanism periodically detects and corrects DC component accumulation by forcing the lens back to the predetermined position, thereby maintaining both responsiveness and stability
Data Source
AI summary
An imaging device includes an imaging lens, an imaging element that captures an image transmitted through the imaging lens, a blur detection part configured to detect a blur, an actuator configured to determine a position of the imaging lens, and an actuator driver configured to control the actuator in accordance with a blur detection signal from the blur detection part. The shift of the image occurring when forcibly changing the position of the imaging lens is corrected by shift of an effective pixel area of the imaging element according to the forcible change amount of the position of the imaging lens.