Magnetic Force Drive Device for Optical Scanning
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Solution Overview
Problem
Conventional magnetic force drive devices for optical scanning devices face challenges in increasing the driving force and deflection angle of optical scanning mirrors, leading to limitations in scanning range and device miniaturization and thinning.
Innovation Solution
A magnetic force drive device with a non-magnetic movable plate, a permanent magnet, and a yoke-coil configuration where the yoke's end parts are magnetized in different polarities to enhance the magnetic field and driving force, allowing for increased deflection angles and scanning ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the driving force is increased by increasing current or coil turns, then the deflection angle increases, but the device size and power consumption increase
Solution Approach 1:
The patent applies local quality by concentrating the magnetic field in specific regions where it is most effective. The coil is positioned to generate a strong magnetic field only in the gap region between the permanent magnet and the movable plate, rather than distributing the field uniformly throughout the entire device. This localized field concentration increases the driving force density, allowing for higher deflection angles without proportionally increasing the overall device volume.
Solution Approach 2:
The patent changes key parameters including the magnetization direction of the permanent magnet (oriented in the thickness direction rather than in-plane), the positioning of the coil relative to the permanent magnet, and the magnetic permeability distribution through the use of a yoke structure. These parameter changes optimize the magnetic field generation efficiency, enabling stronger driving force from a more compact coil configuration, thus increasing deflection angle without linearly increasing device size.
2Force
If the driving force is increased by increasing current or coil turns, then the deflection angle increases, but power consumption increases
Solution Approach 1:
The patent optimizes the magnetic field generation efficiency by changing the magnetization direction of the permanent magnet to be in the thickness direction, positioning the coil to maximize flux linkage, and using a yoke structure with optimized magnetic permeability. These parameter changes increase the magnetic coupling between the coil and permanent magnet, thereby increasing the driving force for a given current, which reduces the current required and thus lowers power consumption for achieving the same deflection angle.
Solution Approach 2:
The patent segments the magnetic circuit into distinct functional regions: the permanent magnet provides a static magnetic field, the coil provides a controllable magnetic field, and the yoke provides a low-reluctance path. This segmentation allows each component to be optimized independently for its specific function, improving overall magnetic circuit efficiency and reducing energy losses, thereby lowering power consumption for a given driving force output.
3Force
If the torsional modulus of elasticity is decreased to increase deflection angle, then the deflection angle increases, but the resonance frequency decreases causing overlap with driving frequency
Solution Approach 1:
The patent takes preliminary action by carefully designing the beam part dimensions and material properties during the design phase to achieve the optimal balance between deflection angle and resonance frequency. The beam part is designed with specific thickness and width ratios that provide sufficient flexibility for large deflection angles while maintaining adequate stiffness to keep the resonance frequency above the driving frequency, preventing resonance overlap before the device operates.
Solution Approach 2:
The patent changes the geometric parameters of the beam part (thickness, width, length ratios) and selects materials with appropriate elastic properties to achieve the desired balance. By adjusting these parameters, the patent optimizes the torsional modulus of elasticity to provide large deflection angles while maintaining a resonance frequency that does not overlap with the driving frequency, thus avoiding the harmful resonance condition.
4Volume of moving object
If the device is miniaturized to reduce size, then the device volume decreases, but the driving force and deflection angle decrease
Solution Approach 1:
The patent applies local quality by concentrating the magnetic field in the narrow gap region between the permanent magnet and the movable plate. This localized field concentration creates a high magnetic flux density in a small volume, generating strong driving force despite the overall miniaturization of the device. The coil is positioned to maximize the magnetic field strength in this critical gap region, enabling efficient force generation in a compact form factor.
Solution Approach 2:
The patent changes the magnetization direction of the permanent magnet to be in the thickness direction, which optimizes the magnetic field distribution in the vertical direction where the gap is smallest. This parameter change, combined with optimized coil positioning and yoke structure, maximizes the magnetic coupling efficiency in the miniaturized device, enabling strong driving force from a reduced device volume.
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 enables a significant increase in the deflection angle of the optical scanning mirror, enhancing the scanning range and allowing for miniaturization and thinning of image display devices while maintaining low power consumption.
Implementation Method 1
a permanent magnet that is fixed to the first movable plate and magnetized in a direction that is substantially parallel to a main surface of the first movable plate
Implementation Method 2
drive the first movable part utilizing the magnetic interaction that is produced by applying a current to the coil
Implementation Method 3
a first driving unit, having a yoke and a coil that magnetizes the yoke
Data Source
AI summary
A magnetic force drive device (7) has the first movable part (100) and the first driving unit (200). The first movable part (100) has the first movable plate (111), and a permanent magnet (120) that is magnetized in a direction substantially parallel to the first movable plate (111), and is supported by the first frame body (112) and the first pair of beam parts (113), so as to be able to oscillate around the Y axis, which is substantially parallel to the first movable plate (111) and substantially perpendicular to the direction in which the permanent magnet (120) is magnetized. The first driving unit (200) has a yoke (210), and a coil (220) that magnetizes the yoke (210). The yoke (210) has the first end part (211a), and a second end part (212a) that is placed on substantially the opposite side of the first end part (211a) against one magnetic pole of the permanent magnet (120). The first end part (211a) and second end part (212a) are magnetized in mutually different polarities, and drive the first movable part (100) in the same oscillation direction.