Leaf-Spring Oscillation Drive for Fast Pixel Shifting
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Solution Overview
Problem
Conventional oscillation drive devices for pixel shifting in projection-type image display apparatuses face challenges in achieving high-speed oscillatory movement and downsizing due to the large moment of inertia caused by the mass of copper wire coils, which hinders efficient pixel shifting and image resolution improvement.
Innovation Solution
The oscillation drive device incorporates a rectangular toroidal coil with a unique configuration of strip-shaped leaf springs and a flexible beam portion, reducing the moment of inertia by optimizing the placement of the oscillation axis and using a voice coil motor with L-shaped yokes, and eliminating the torsional beam portion to minimize size and enhance response characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the side of the coil serving as the voice coil motor is arranged farther away from the center of oscillation, then the torque is increased, but the moment of inertia is increased making it difficult to achieve high-speed oscillatory movement
Solution Approach 1:
The coil is divided into multiple sides with different functions: one side serves as the voice coil motor while the other sides serve as magnetic flux return paths. This segmentation allows the voice coil to be positioned optimally for torque generation without requiring the entire coil structure to be extended, thus avoiding excessive moment of inertia.
Solution Approach 2:
The patent transitions from a conventional cylindrical voice coil motor to a rectangular toroidal coil configuration, changing the spatial arrangement from three-dimensional cylindrical symmetry to a planar rectangular structure. This dimensional change enables better optimization of the distance between the voice coil and oscillation center while controlling the overall moment of inertia.
2Power
If a cylindrical voice coil motor is used to efficiently produce thrust force, then the motor efficiency is improved, but the device size increases making downsizing difficult
Solution Approach 1:
The rectangular toroidal coil is divided into functional segments: one side acts as the voice coil motor for thrust generation, while the other three sides act as magnetic flux return paths. This segmentation creates a compact structure that is more space-efficient than a cylindrical configuration while maintaining effective thrust force generation.
Solution Approach 2:
The rectangular toroidal coil structure utilizes thin wire windings that form a flexible magnetic circuit, replacing the rigid cylindrical yoke structure. This allows for a more compact and lightweight design that achieves the same magnetic flux efficiency with reduced volume.
3Volume of moving object
If the coil mass is reduced for downsizing, then the device size decreases, but the magnetic flux efficiency may be compromised
Solution Approach 1:
By segmenting the rectangular toroidal coil into functional regions, the patent optimizes the distribution of wire mass. The voice coil side uses sufficient winding density for efficient thrust generation, while the flux return sides use lighter construction, achieving overall mass reduction without compromising magnetic flux efficiency.
Solution Approach 2:
The patent employs composite construction combining copper wire windings with non-magnetic support structures and magnetic materials strategically placed only where needed for flux guidance. This composite approach reduces overall mass while maintaining magnetic flux efficiency through optimized material placement.
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 configuration enables high-speed oscillatory movement while downsizing the device, improving response characteristics and reducing fluctuations in pixel shift, thereby enhancing image resolution and maintaining high-quality image projection.
Implementation Method 1
The oscillation drive device includes an oscillating unit, a base, and a pair of strip-shaped leaf springs. The oscillating unit includes a rectangular toroidal coil, a center yoke, a back yoke, and a permanent magnet. When current flows through the coil, it interacts with the magnetic field from the permanent magnet to generate thrust force, producing oscillatory movement.
Implementation Method 2
In this voice coil motor, it is configured that an end of a yoke arranged on the back side of the magnet (a back yoke) is in contact with an end of the center yoke. By this configuration, a magnetic flux of the magnet runs in cycle, and thereby improving the efficiency of the voice coil motor.
Implementation Method 3
a pair of strip-shaped leaf springs that are arranged so as to intersect with the oscillation axis and oscillate the oscillating unit on the oscillation axis, and a flexible beam portion that both ends of which are attached to the supporting portions of the base, and causes the oscillating unit to oscillate on the base by flexure behavior thereof.
Data Source
AI summary
An oscillation drive device includes an oscillating unit that includes attaching portions on either sides thereof, the attaching portions being arranged on an oscillation axis; a base that includes an oscillating fulcrum that supports the oscillating unit on the oscillation axis and supporting portions that firmly support the oscillating unit; and a pair of strip-shaped leaf springs that is arranged so as to intersect with the oscillation axis and oscillates the oscillating unit on the oscillation axis, each of the strip-shaped leaf springs includes a fixing portion attached to the attaching portions of the oscillating unit; and a flexible beam portion that both ends of which are attached to the supporting portions of the base, and causes the oscillating unit to oscillate on the base by flexure behavior thereof.