Voice Coil Motor Lens Position Control for Endoscope Reliability
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Solution Overview
Problem
Endoscope systems face challenges in maintaining focus and image quality due to unreliable position detection of moving lenses, particularly under temperature and humidity variations, which can lead to loss of resolution during medical procedures.
Innovation Solution
An optical system incorporating a voice coil motor, position detection unit, and drive control unit that determines the normalcy of position signals and adjusts current flow in the motor coils to maintain focus, ensuring continued image quality even if the position detection fails, by moving the movable frame to maximize focal length and prevent loss of resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a position detection device is used to detect the position of a moving lens, then autofocus control is enabled, but the device may fail due to temperature, humidity, or electrical weaknesses
Solution Approach 1:
The patent uses the voice coil motor's own drive signals and electrical characteristics as an intermediary to infer lens position, rather than relying on a separate position detection device that is vulnerable to environmental factors. The control unit monitors the electrical characteristics of the voice coil motor during drive operations to determine lens position indirectly.
Solution Approach 2:
The system uses the voice coil motor's inherent electrical characteristics and drive behavior to provide position information, making the motor serve dual purposes: both actuation and position sensing. This eliminates the need for a separate, vulnerable position detection device.
2Measurement precision
If autofocus is performed using a voice coil motor, then focus control is improved, but the system loses redundancy when position detection fails
Solution Approach 1:
The control unit continuously monitors the electrical characteristics of the voice coil motor during drive operations and uses this feedback to determine lens position and detect abnormalities. The system adjusts drive signals based on this feedback to maintain focus control even when position detection fails.
Solution Approach 2:
The patent prepares for position detection failure by establishing alternative control methods in advance. The control unit is designed to switch to using electrical characteristic monitoring when position detection abnormalities are detected, ensuring continuous focus control capability without pulling out the endoscope.
3Ease of repair
If the endoscope is pulled out to replace a failed position detection device, then the device can be repaired, but treatment must be interrupted and resolution is lost
Solution Approach 1:
The system performs its own position detection function through the voice coil motor's electrical characteristics, eliminating the need for separate position detection devices that require external repair. The control unit autonomously switches to alternative control methods when abnormalities are detected.
Solution Approach 2:
The patent establishes backup control methods in advance that allow the system to continue operating without position detection devices. When position detection fails, the control unit switches to using electrical characteristic monitoring, preventing treatment interruption.
4Reliability
If the movable frame is moved to maximize focal length when position detection fails, then image quality is maintained, but the system must detect and respond to detection failures
Solution Approach 1:
The control unit performs multiple functions: normal autofocus control, position detection failure detection through electrical characteristic monitoring, and alternative control execution. This multi-functionality is achieved within the existing control unit without adding separate detection and response systems.
Solution Approach 2:
The patent combines the position detection failure detection function and alternative control function into the existing control unit, merging multiple responsibilities into a single component. The control unit monitors electrical characteristics and executes alternative control based on the same drive signals used for normal operation.
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 solution enables the endoscope system to maintain image quality and continue medical treatments without losing resolution, even if the position detection fails, by ensuring the movable frame is driven to a position that maximizes focal length, thus preventing image degradation and allowing for effective treatment continuation.
Implementation Method 1
a voice coil motor including a magnet and a coil and configured to move the first movable frame relative to the holding frame along the predetermined direction
Data Source
AI summary
An optical system includes: a first optical element; a first movable frame; a holding frame; a voice coil motor; a first position detection unit configured to detect information related to a position of the first movable frame with respect to the holding frame and generate a first position signal; a determination unit configured to determine whether the first position signal is normal; and a drive control unit configured to perform, when the determination unit determines that the first position signal is normal, first drive control for driving the first movable frame by controlling, based on the first position signal, a current allowed to flow in the coil or configured to perform, when the determination unit determines that the first position signal is not normal, second drive control for driving the first movable frame by flowing a current with a predetermined value in the coil.