Camera Lens Controller Resonance Suppression for High Frame Rate Noise
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Solution Overview
Problem
In interchangeable lens camera devices, high frame rates during moving image capture lead to increased inertial force and vibration, resulting in noise due to the resonant frequency of the focus lens drive unit, making it difficult to synchronize Wob driving with frame rate and reduce noise simultaneously.
Innovation Solution
A camera device with a lens drive unit, position detector, and controller that performs up-sampling of the driving amount signal and uses a resonance suppression calculator to attenuate higher-order resonant frequency components, employing digital filter processing to reduce noise during AF operations at high frame rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the frame rate is increased to 120 fps for high quality moving image capture, then the image quality is improved, but the inertial force and vibration of the focus lens drive unit increase, causing noise
Solution Approach 1:
The patent applies preliminary action by pre-calculating and suppressing resonant frequency components in the drive signal before the Wob driving operation begins. The resonance suppression calculator identifies and attenuates frequency components that would excite the drive unit's resonant frequencies, preventing noise generation before it occurs during high-speed Wob driving at 120 fps
Solution Approach 2:
The patent changes parameters by dynamically adjusting the drive signal's frequency spectrum through resonance suppression processing. By modifying the frequency domain characteristics of the drive signal to eliminate resonant frequency components, the system enables high frame rate operation without exciting the drive unit's natural frequencies, thus reducing noise while maintaining image quality
2Manufacturing precision
If the focus lens is Wob-driven at high frame rate, then the image quality is improved, but the driving sound increases due to resonant frequency excitation
Solution Approach 1:
The resonance suppression calculator performs preliminary processing on the Wob drive signal to identify and attenuate frequency components that would excite the drive unit's resonant frequencies. This pre-suppression prevents driving sound generation before the high-speed Wob driving begins, allowing clear audio recording during movie capture
Solution Approach 2:
The patent converts the harmful effect of resonant frequency excitation into a benefit by using the known resonant frequency characteristics of the drive unit to design targeted suppression filters. By identifying the problematic frequencies and selectively attenuating them, the system transforms the understanding of resonance from a source of noise into a tool for precise noise control, enabling high frame rate Wob driving without driving sound
3Object-generated harmful factors
If the maximum speed of the focus lens is suppressed to reduce vibration, then the noise is reduced, but it becomes difficult to synchronize Wob driving with frame rate
Solution Approach 1:
The system performs preliminary resonance suppression processing on the drive signal before Wob driving begins, establishing a stable frequency spectrum that won't excite resonant frequencies. This pre-processing enables the focus lens to be driven at speeds necessary for frame rate synchronization without generating noise, as the harmful resonant frequency components are removed in advance
Solution Approach 2:
The patent changes the frequency domain parameters of the drive signal by attenuating specific frequency components that correspond to the drive unit's resonant frequencies. This selective parameter modification allows the drive signal to maintain the amplitude and timing characteristics needed for frame rate synchronization while eliminating the frequency components that would cause noise
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 effectively reduces noise generated by the AF operation at high frame rates by suppressing higher-order resonant frequencies, allowing for synchronized Wob driving and improved image quality.
Implementation Method 1
an imaging element (203) for generating image data by performing photoelectric conversion
Data Source
AI summary
A lens controller of a camera device includes: a driving amount calculator that samples, for each first time period, a lens position signal indicating a lens position detected by a lens position detector and a target position signal indicating a target position of a focus lens on an optical axis transmitted from a control unit and calculates a driving amount output of the focus lens based on the sampled lens position signal and target position signal; an up-sampling unit that performs up-sampling on the driving amount output obtained by the driving amount calculator at a second time period which is a period obtained by dividing the first time period by an integer; and a resonance suppression calculator that performs calculation on a result obtained by sampling the driving amount output at the second time period to suppress a higher-order resonant frequency component in a specified resonant frequency band.