Anti-shake System Using Time-sharing A/D Conversion
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Solution Overview
Problem
Existing anti-shake systems for video cameras have limited dynamic range and large circuit scales due to the dynamic range and accuracy being determined by the A/D converter, which leads to inefficiencies in processing shake detection signals.
Innovation Solution
The system employs a method of processing shake detection signals by subjecting analog signals to linear operations with different gains, time-sharing A/D conversion, and selecting digital signals based on saturation levels to generate a wide dynamic range with a smaller circuit scale, allowing for accurate shake compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single A/D converter is used to process shake detection signals, then the circuit scale is kept small, but the dynamic range and measurement precision are limited
Solution Approach 1:
The patent divides the shake detection signal processing into two segments: a first A/D converter processes the original shake detection signal, while a second A/D converter processes a differentiated signal. This segmentation allows each converter to operate within its optimal range, collectively achieving a wider dynamic range without requiring a single complex high-precision converter.
Solution Approach 2:
The patent transforms the problem from a single-dimensional signal processing approach to a two-dimensional approach by introducing signal differentiation. The differentiated signal provides additional information about signal changes, enabling the system to capture both small amplitude shakes (through the original signal) and large amplitude shakes (through the differentiated signal), effectively expanding the dynamic range.
2Measurement precision
If high-gain amplification is applied to shake detection signals to improve measurement precision, then small shakes can be detected, but large shakes cause saturation and loss of information
Solution Approach 1:
The patent implements dynamic signal processing by switching between two different processing paths based on signal characteristics. When the differentiated signal indicates large amplitude changes, the system uses the second A/D converter to avoid saturation. When changes are small, the first A/D converter provides sufficient precision. This dynamic adaptation prevents information loss across varying shake intensities.
Solution Approach 2:
The patent changes the processing parameters (gain, conversion timing) based on the input signal characteristics. By monitoring the differentiated signal and adjusting which A/D converter is active, the system optimizes the conversion gain and timing parameters to match the current shake amplitude, thereby maintaining measurement precision without causing saturation.
3Measurement precision
If multiple A/D converters operate simultaneously with different gains, then wide dynamic range is achieved, but circuit complexity and processing time increase
Solution Approach 1:
The patent employs periodic switching between the two A/D converters based on the signal characteristics detected by the differentiation circuit. Rather than operating both converters continuously, the system periodically selects the appropriate converter, reducing processing overhead while maintaining the ability to handle both small and large amplitude shakes effectively.
Solution Approach 2:
The patent extracts only the necessary processing path from the two possible A/D conversion routes. By using the differentiated signal to determine which converter should be active, the system takes out only the required processing branch, avoiding the time penalty of processing through both converters simultaneously while still achieving wide dynamic range coverage.
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
This approach enables a video camera with a wide dynamic range and a reduced circuit scale, effectively compensating for camera shakes with high accuracy and efficiency.
Implementation Method 1
an image sensor for converting incident light into an electric signal
Data Source
AI summary
A shake sensor outputs an analog shake detection signal representative of a shake of a camera body. An amplifier operates for amplifying the analog shake detection signal to generate an analog amplification-resultant signal. The analog shake detection signal and the analog amplification-resultant signal are converted into a digital shake detection signal and a first digital amplification-resultant signal, respectively. A signal value represented by the digital shake detection signal is amplified on a digital basis to generate a second digital amplification-resultant signal. A decision is made as to whether or not the signal value represented by the first digital amplification-resultant signal remains greater than a predetermined reference value during at least a prescribed time interval. One is selected from the first and second digital amplification-resultant signals in response to the result of the decision. A shake corrective signal is generated in response to the selected signal.