Composite Low-Frequency Filter for Camera Shake Phase Matching
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Solution Overview
Problem
Conventional imaging apparatuses face challenges in achieving effective camera shake correction due to phase mismatch between actual camera shake and correction angles caused by limitations in the integral band of the integrator and low frequency cutoff filters, leading to insufficient suppression of camera shake.
Innovation Solution
A composite low frequency cutoff filter is implemented, comprising a first and second low frequency cutoff filter and an adder-subtractor, which cancels out phase lead caused by the integrator, ensuring zero phase fluctuation on the low frequency side of the camera shake correction band, thereby achieving excellent camera shake correction performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the order of the filter is increased to allow the phases to match each other, then the phase matching between actual camera shake and correction angle is improved, but the computation algorithm becomes complicated and the circuit structure becomes complicated
Solution Approach 1:
The patent divides a high-order filter into multiple first-order filters connected in series. Specifically, a second-order low-pass filter is segmented into two first-order low-pass filters (104a and 104b), each with different cutoff frequencies. This segmentation maintains the phase correction effectiveness while significantly simplifying the computation algorithm and circuit structure compared to implementing a single high-order filter.
2Measurement precision
If the order of the filter is increased to allow the phases to match each other, then the phase matching between actual camera shake and correction angle is improved, but the circuit structure becomes complicated
Solution Approach 1:
The patent divides a high-order filter into multiple first-order filters connected in series. Specifically, a second-order low-pass filter is segmented into two first-order low-pass filters (104a and 104b), each with different cutoff frequencies. This segmentation maintains the phase correction effectiveness while significantly simplifying the computation algorithm and circuit structure compared to implementing a single high-order filter.
3Reliability
If a low frequency cutoff filter is provided to reduce extremely low frequency fluctuating components, then the camera shake correction performance is improved, but the phase on the low frequency side advances causing phase mismatch
Solution Approach 1:
The patent introduces an integrator (105) as an intermediary component between the low frequency cutoff filter (104) and the camera shake correction system. The integrator compensates for the phase advance caused by the low frequency cutoff filter by introducing a corresponding phase lag. This intermediary element allows the system to maintain both the noise filtering benefit and the phase accuracy needed for effective camera shake correction.
Data Source
AI summary
An imaging apparatus includes a composite low frequency cutoff filter. The composite low frequency cutoff filter includes a first low frequency cutoff filter, a second low frequency cutoff filter, and an adder-subtractor. The second low frequency cutoff filter receives an output of the first low frequency cutoff filter. The adder-subtractor subtracts an output of the second low frequency cutoff filter from an input to the composite low frequency cutoff filter, and outputs a result of the subtraction to the first low frequency cutoff filter. An output of the first low frequency cutoff filter is outputted as an output of the composite low frequency cutoff filter.