SMA Motor Control for Noise-Free Image Sensor Sampling
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Solution Overview
Problem
Shape memory alloy (SMA) motors in photographing apparatuses generate noise stripes in images due to interference from detection signals during correlated double sampling (CDS) by the image sensor.
Innovation Solution
A control method for SMA motors that outputs equal-width detection signals at specific times corresponding to the CDS sampling times of the image sensor, ensuring equal interference and minimizing noise stripes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If detection signals are output during CDS sampling, then SMA wire deformation can be detected, but noise stripes appear in the generated image
Solution Approach 1:
The detection signal is output periodically at specific timing intervals that correspond to the CDS sampling periods. By synchronizing the detection signal output with the CDS sampling rhythm, the interference caused by detection signals becomes periodic and can be effectively canceled out during the correlated double sampling process, thereby eliminating noise stripes while maintaining deformation detection capability
Solution Approach 2:
The system uses the detection signal to continuously monitor SMA wire deformation and feeds this information back to the controller. The controller adjusts the drive signal based on this feedback to achieve closed-loop control, ensuring accurate focus or stabilization while the periodic timing arrangement prevents interference noise
2Measurement precision
If detection signal width differs from drive signal width, then detection accuracy may improve, but interference to CDS sampling becomes unequal
Solution Approach 1:
The detection signal is designed to have the same pulse width as the drive signal, creating equipotential conditions for interference. This ensures that both the first sampling and second sampling in CDS experience equal interference levels, allowing the correlated double sampling to effectively cancel out the interference and eliminate noise stripes in the final image
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 method effectively eliminates noise stripes in images by balancing the interference caused by detection signals during CDS, improving image quality and user experience.
Implementation Method 1
the at least one SMA wire is configured to deform to drive the lens to move
Data Source
AI summary
A photographing apparatus includes a shape memory alloy (SMA) motor, an image sensor, a lens, and a controller. The SMA motor includes an SMA wire. The SMA wire is configured to deform to drive the lens to move. The controller is configured to output a pulse signal. The pulse signal includes a drive signal and a detection signal. The drive signal is used to cause the SMA wire to deform. The detection signal is used to detect deformation of the SMA wire. N times a pulse signal cycle is equal to a time difference between the first time of sampling and the second time of sampling in correlated double sampling of the image sensor.