Motorized Optical Lens Drive With Spring-Biased Axial Positioning
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Solution Overview
Problem
Existing optical devices with motors designed for axial play suffer from imprecise control of the control member's motion due to inaccurate positioning, especially when encoder-based motion control lacks information on the actual control member position.
Innovation Solution
The optical device incorporates a driving member rotatably mounted in the framework with biasing means, such as spring washers or coil springs, to maintain the driving member in a predetermined axial position, ensuring precise control of the control member's motion and thus accurate optical power adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motors are designed with axial play in the output shaft to ensure proper functioning in a wide range of temperatures, then the motor can operate reliably across temperature variations, but the positioning of the driving member becomes inaccurate and control precision deteriorates
Solution Approach 1:
A biasing member (spring element) is introduced as an intermediary component between the driving member and the motor output shaft. This spring element absorbs the axial play in the motor output shaft while maintaining precise positioning of the driving member through elastic deformation, thus mediating between the unreliable motor positioning and the precision requirements of the control member positioning.
Solution Approach 2:
The system changes the physical state of the positioning mechanism by introducing an elastic element that dynamically adjusts its deformation based on thermal expansion and contraction. As temperature varies, the spring element compresses or extends to compensate for output shaft movement, maintaining constant positioning precision of the driving member regardless of temperature-induced parameter changes in the motor.
2Adaptability or versatility
If axial play is introduced in the motor output shaft for temperature compensation, then the motor functions properly across temperatures, but the control of control member motion becomes imprecise
Solution Approach 1:
The biasing member acts as a mediator that decouples the temperature compensation function from the positioning function. It allows the motor to have axial play for temperature adaptability while independently maintaining precise control member positioning through its elastic properties.
Solution Approach 2:
The spring element provides beforehand cushioning by pre-compressing or pre-extending to absorb anticipated thermal expansion or contraction of the motor output shaft. This cushioning effect prevents thermal movements from translating into positioning errors of the control member.
3Device complexity
If encoder-based motion control is used without information on actual control member position, then the system structure is simplified, but positioning accuracy deteriorates due to driving member positioning errors
Solution Approach 1:
The biasing member enables the system to self-correct positioning errors without external feedback. The elastic element automatically compensates for motor output shaft play, making the system self-sufficient in maintaining precision without requiring complex feedback mechanisms or additional sensors.
Solution Approach 2:
The spring element serves as a passive intermediary that mechanically ensures accurate transmission of motion from the driving member to the control member, eliminating the need for active feedback systems and simplifying the control architecture while maintaining precision.
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 precise control of the optical power provided by the optical device, improving the accuracy of optical corrections by maintaining the driving member in a precise axial position, even in the absence of direct information on the control member's position.
Implementation Method 1
the biasing means are suitable for exerting along said output shaft axis a biasing force greater than a force exerted by the driving member on the control member for driving the control member into motion
Data Source
AI summary
An optical device including a lens and a control member configured such that motion of the control member produces a change in the optical power provided along an optical axis of the lens. The optical device further includes a framework, a motor and a driving member. The motor includes an output shaft rotatively coupled to said driving member. The motor and the control member are mounted in the framework such that the driving member and the control member mechanically cooperate. The driving member is rotatably mounted in the framework. The optical device comprises biasing means for maintaining the driving member in a predetermined axial position along the output shaft axis and relative to the framework. This optical device can be used in an optometric equipment.