Image Stabilization Control Circuit Using Floating-Point Integration
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Solution Overview
Problem
Current image stabilization control circuits in image-capturing devices face challenges with power consumption and accuracy due to the use of microprocessors for gyro-filter functions, particularly when performing calculations in fixed-point format, which can lead to overflow issues and decreased accuracy.
Innovation Solution
The implementation of a digital filter circuit that converts displacement velocity data from fixed-point to floating-point format, performs high-pass filtering, integration, and then converts back to fixed-point format, preventing overflow and ensuring accurate vibration compensation data generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a microprocessor is used for gyro-filter functions, then image stabilization responsiveness is improved, but power consumption increases
Solution Approach 1:
The patent replaces the microprocessor-based software gyro-filter with a dedicated digital filter circuit that performs the same gyro-filtering function. This circuit substitution eliminates the need for a microprocessor while maintaining the image stabilization responsiveness, thereby significantly reducing power consumption.
Solution Approach 2:
The patent extracts the gyro-filter function from the microprocessor and implements it as a separate, dedicated digital filter circuit. This extraction allows the system to perform gyro-filtering operations without requiring a full microprocessor, thus reducing power consumption while preserving responsiveness.
2Device complexity
If calculations are performed in fixed-point format, then circuit structure is simplified, but calculation accuracy decreases due to overflow
Solution Approach 1:
The patent changes the numerical representation parameter from fixed-point format to floating-point format for the integration circuit. This parameter change prevents overflow during integration calculations, thereby maintaining calculation accuracy while still using a relatively simple digital filter circuit structure.
Solution Approach 2:
The patent uses floating-point format in the integration circuit as a preventive measure against overflow. By anticipating the potential overflow problem in fixed-point integration, the system employs floating-point representation to cushion against accuracy loss before it occurs.
3Reliability
If data culling or gain multiplication is used to prevent overflow, then overflow is avoided, but circuit structure becomes complicated
Solution Approach 1:
The patent replaces complex software-based overflow prevention methods (data culling, gain multiplication) with a simpler hardware-based solution using floating-point format in the integration circuit. This substitution maintains reliability by preventing overflow while avoiding the circuit complexity associated with software-based methods.
Data Source
AI summary
An image stabilization control circuit of an image-capturing device prevents overflow of data in an integration process performed in a digital signal process on a signal outputted by a gyro-sensor. A gyro-filter receives, as an input, fixed-point format angular velocity data (Dω) obtained by subjecting an output signal from the gyro-sensor to an analog-to-digital conversion. In the gyro-filter, an input format conversion circuit converts from fixed-point format to floating-point format. A camera shake vibration component is obtained from the floating-point format Dω, is integrated, and data (Dθ) corresponding to an oscillation angle is generated. After a centering process is performed, Dθ is converted from floating-point format to fixed-point format by an output format conversion circuit, and outputted from the gyro-filter. A drive signal for driving an image stabilization mechanism is generated on the basis of the data outputted by the gyro-filter.