Analog Image Stabilization Circuit Phase Compensation
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Solution Overview
Problem
Existing image stabilization control circuits in image-capturing devices face accuracy issues due to phase delay in the output signal of gyro-sensors, leading to reduced accuracy in vibration compensation, especially in high-frequency regions, which affects the power consumption and operational time of the device.
Innovation Solution
The implementation of an image stabilization control circuit with a high-pass filter for camera shake component extraction, an integration circuit using a low-pass filter, and phase lead compensation circuits to address phase delays, allowing for accurate vibration compensation without the need for a microprocessor, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a microprocessor is used to implement the gyro-equalizer for image stabilization, then the processing capability and flexibility are improved, but the power consumption increases rapidly
Solution Approach 1:
The patent replaces the microprocessor-based digital processing system with an analog circuit implementation. The gyro-equalizer is realized using operational amplifiers, resistors, and capacitors to perform the necessary signal processing functions (integration, differentiation, and phase compensation) in the analog domain, thereby eliminating the high power consumption associated with high-speed microprocessor operation.
Solution Approach 2:
The patent employs operational amplifier circuits with carefully selected RC time constants to simulate the mechanical integration and differentiation processes. The analog circuitry uses electrical equivalents of mechanical systems, where capacitors store and release energy analogous to mechanical springs, achieving the same signal processing effects with minimal power consumption.
2Device complexity
If the gyro-sensor output signal is used directly for integration, then the circuit simplicity is maintained, but the phase delay in high-frequency regions reduces the accuracy of vibration compensation
Solution Approach 1:
The patent divides the signal processing into distinct functional stages: a high-pass filter section to remove low-frequency drift, an integration section to convert angular velocity to angular position, and a phase compensation section to correct high-frequency phase delays. Each stage is implemented with dedicated analog circuits, allowing precise control of the overall frequency response without excessive complexity.
Solution Approach 2:
The patent adjusts the RC time constants and feedback resistor values in the operational amplifier circuits to optimize the frequency response. By carefully selecting these parameters, the circuit achieves the desired integration function while compensating for the gyro-sensor's inherent phase delays in the high-frequency region, thereby maintaining accuracy across the operating bandwidth.
3Device complexity
If the integration process is performed without phase compensation, then the circuit complexity is reduced, but the accuracy of displacement magnitude calculation deteriorates
Solution Approach 1:
The patent introduces an intermediate phase compensation circuit between the high-pass filter and the final output stage. This intermediate stage uses additional operational amplifiers with specific feedback networks to advance the phase of the integrated signal, counteracting the phase lag introduced by the gyro-sensor and the integration process itself, thereby improving the accuracy of the displacement magnitude calculation.
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
The solution enhances the accuracy of vibration compensation, extends the operational time of image-capturing devices by minimizing power consumption, and allows for effective camera shake correction across various frequency regions.
Implementation Method 1
a camera shake component extraction process can be configured using a high frequency pass filter (high pass filter, or HPF)
Implementation Method 2
It is possible to perform an integration process by using a low frequency pass filter (low pass filter, or LPF)
Implementation Method 3
phase lead compensation circuits to address phase delays
Data Source
AI summary
In an image stabilization control circuit of an image-capturing device, a gyro-equalizer (24) is used to integrate an angular velocity signal corresponding to vibration, and determine a required magnitude of displacement of a lens. The gyro-equalizer (24) integrates the angular velocity signal from a gyro-sensor (12) using an integration circuit (46) (LPF), and converts the result into an angular signal. A direct-current component of the angular signal is removed using a centering circuit (52) (HPF). Excessive phase delay of the angular signal on a high-frequency side caused by a phase characteristic of the gyro-sensor (12) is compensated by a phase lead compensation circuit (50) composed of a high-boost filter, and the phase delay of the angular signal with respect to the angular velocity signal is brought nearer to 90° by an integration process.