Voice Coil Actuator Integrated LVDT for Fast Lens Positioning
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Solution Overview
Problem
Stepping motors with position feedback operate too slowly for many applications, necessitating a faster alternative for precise lens positioning in medical devices.
Innovation Solution
Integration of a voice coil actuator with a linear voltage displacement transducer (LVDT) for position sensing, allowing the voice coil to provide accurate armature position feedback and enable quick, precise movement of a lens-mounted tube, enabling faster and more accurate focusing of a laser beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stepping motor with position feedback is used to position the lens barrel, then positioning accuracy is improved, but the response speed becomes too slow for most applications
Solution Approach 1:
The patent combines the voice coil actuator and LVDT position sensor into a single integrated assembly where the LVDT core is mechanically coupled to the voice coil armature. This merging eliminates the need for separate positioning and sensing components, enabling fast response from the voice coil while maintaining accurate position feedback from the LVDT, thus resolving the contradiction between speed and positioning accuracy.
Solution Approach 2:
The integrated LVDT provides continuous position feedback to the control system, which adjusts the voice coil current to achieve precise positioning. The feedback loop enables the fast voice coil actuator to maintain accurate positioning control, resolving the contradiction by using rapid feedback to guide the high-speed actuator.
2Speed
If a voice coil actuator without position feedback is used, then response speed is improved, but positioning accuracy deteriorates
Solution Approach 1:
The patent integrates the LVDT position sensor directly with the voice coil actuator, combining fast actuation with accurate sensing in a single assembly. The LVDT core is coupled to the voice coil armature, enabling the system to achieve both high response speed from the voice coil and precise position measurement from the LVDT, thus resolving the contradiction between speed and positioning accuracy.
Solution Approach 2:
The integrated LVDT provides continuous position feedback to the control system, which uses this information to precisely control the voice coil actuator's movement. The feedback mechanism enables the fast-response voice coil to achieve accurate positioning by continuously adjusting based on real-time position data, resolving the contradiction between speed and positioning accuracy.
3Measurement precision
If a separate LVDT sensor is mechanically coupled to the lens barrel, then positioning accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges the LVDT position sensor and voice coil actuator into a single integrated assembly where the LVDT core is mechanically coupled to the voice coil armature. This integration eliminates the need for separate mounting and coupling mechanisms, reducing structural complexity while maintaining accurate position sensing capability.
Solution Approach 2:
The integrated assembly serves multiple functions simultaneously: the voice coil provides actuation while the LVDT provides position sensing, and they are mechanically coupled so that a single component (the armature/core assembly) performs both actuation and sensing functions. This multi-functionality reduces the number of separate components and simplifies the overall device structure.
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 voice coil actuator with integrated LVDT position sensing enables faster and more accurate positioning of a lens, reducing equipment use time during medical procedures by providing precise control over the movement of the lens and laser beam focus.
Implementation Method 1
Voice coil actuators are generally available in either the moving magnet or moving coil type. The moving coil actuators are also referred to as voice coils.
Implementation Method 2
The LVDT converts rectilinear motion of an object to which it is coupled mechanically into a corresponding electrical signal. In operation, the LVDT's primary winding is energized by alternating current, also called the primary excitation. The LVDT's electrical output signal is the differential AC voltage between the two secondary windings, which varies with the axial position of the core within the LVDT coil.
Implementation Method 3
The voice coil 6 is comprised of a moving armature assembly 21 which consists of a unitary piece non-magnetic core tube 22, which may be made of brass, non-magnetic spacers 24, which also may be made of brass, multiple ferromagnetic armatures 26, and multiple permanent magnets 28 in opposite polarity.
Data Source
AI summary
A device for focusing a laser in which a voice coil and LVDT are mounted in parallel alignment with each other and have a common centrally disposed armature. A central bore extends through the armature. A lens is mounted at one end of the armature and a laser is located at the opposite end. The laser beam passes through the central bore and is focused by the voice coil moving the armature which in turn moves the lens. The LVDT accurately positions the armature to focus the laser beam.