Linear Resonance Scanner With Offset Magnet for Stable Long-Range Scanning
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Solution Overview
Problem
Existing optical scanning systems face challenges in achieving high-frequency, large-range reciprocating motion with minimal vibration and consistent linearity, particularly due to the limitations of piezoelectric and linear resonant actuators, which suffer from short translation ranges, excessive vibration, and inadequate position feedback.
Innovation Solution
A linear resonance scanning apparatus utilizing an electromagnetic drive unit with a coil and a laterally offset permanent magnet, coupled with a biasing element and linear motion bearing assembly, to achieve controlled resonant frequency and amplitude, supported by a mass-spring-damper system for stable oscillation and position feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If piezoelectric actuators are used to achieve high-frequency reciprocating motion, then scan frequency is improved, but translation range deteriorates
Solution Approach 1:
The patent employs resonant vibration of a scanning lens assembly at its natural frequency to achieve high-speed reciprocating motion. The drive unit excites the assembly to vibrate at resonance, enabling scan frequencies above 200 Hz while maintaining translation ranges greater than 5 mm, thus resolving the contradiction between scan frequency and translation range that plagues piezoelectric actuators.
2Length of moving object
If mechanical scanning techniques are used to achieve large translation range, then translation range is improved, but scan frequency deteriorates
Solution Approach 1:
The patent utilizes resonant mechanical vibration to enable the scanning lens assembly to achieve large translation ranges (greater than 5 mm) while maintaining high scan frequencies (above 200 Hz). The drive unit is configured to excite the assembly at its resonant frequency, allowing the system to overcome the inherent limitation of mechanical scanning systems that struggle to meet desired scan rates.
3Strength
If larger moving mass is used in mechanical scanning systems, then structural robustness is improved, but vibration deteriorates
Solution Approach 1:
The patent employs resonant vibration at the natural frequency of the scanning lens assembly, which has a relatively small moving mass. By operating at resonance, the system achieves the required scan frequencies and translation ranges without needing to increase the moving mass, thus avoiding the excessive vibration that would result from using larger mass in mechanical scanning systems.
4Reliability
If flexure assembly is used to support permanent magnet, then positional stability is improved, but translation range deteriorates
Solution Approach 1:
The patent uses resonant vibration to enable the scanning lens assembly to achieve translation ranges greater than 5 mm. The drive unit excites the assembly at its resonant frequency, allowing the system to overcome the limited scan range of flexure assemblies while maintaining positional stability through controlled oscillation at a defined amplitude and frequency.
5Ease of manufacture
If plastic springs are used in electromagnet based actuator, then ease of manufacture is improved, but frequency control deteriorates
Solution Approach 1:
The patent employs resonant vibration with a scanning lens assembly that has well-defined mechanical properties, allowing for precise frequency control. The drive unit is configured to excite the assembly at its natural frequency, and the system includes feedback control to maintain accurate frequency and amplitude, overcoming the frequency control difficulties associated with plastic springs in electromagnet based actuators.
6Device complexity
If open loop control is used in electromagnet based actuator, then device complexity is improved, but position control accuracy deteriorates
Solution Approach 1:
The patent incorporates feedback control to maintain the amplitude of the reciprocating scanning lens assembly constant against external loads. The system includes sensors to detect position and feedback control circuitry to adjust the drive signal, ensuring accurate position control while managing the complexity of the control system.
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 apparatus provides accurate control of resonant amplitude and frequency, supports longer translation ranges, reduces vibration, and maintains consistent performance, making it suitable for optical scanning applications, including confocal and interferometric measurements.
Implementation Method 1
an electromagnetic drive unit comprising a coil wound about a core, the electromagnetic drive unit having a field output end
Implementation Method 2
a biasing element disposed adjacent an end of the linear motion bearing assembly to serve as a buffer for motion along the longitudinal axis of reciprocating motion
Implementation Method 3
a linear motion bearing assembly configured to carry a permanent magnet, the linear motion bearing assembly having a longitudinal axis of reciprocating motion
Implementation Method 4
the permanent magnet is laterally offset with respect to the core so that the core substantially does not overlie the permanent magnet when at rest
Data Source
AI summary
A linear resonance scanning apparatus (100) comprises an electromagnetic drive unit (132) comprising a coil (140) wound about a core (138), the electromagnetic drive unit (132) having a field output end (134). A linear motion bearing assembly (106) is configured to carry a permanent magnet (130), the linear motion bearing assembly (106) having a longitudinal axis of reciprocating motion. A biasing element (122, 126) is disposed adjacent an end of the linear motion bearing assembly (106) to serve as a buffer for motion along the longitudinal axis of reciprocating motion. The permanent magnet (130) has a surface located opposite the field output end (134) of the electromagnetic drive unit (132) in spaced relation to the field output end (134) of the electromagnetic drive unit (132). The permanent magnet (130) is laterally offset with respect to the core (138) so that the core (138) substantially does not overlie the permanent magnet (130) when at rest.