Optical Device Miniaturization via Planar Magnetic Field Guide
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Solution Overview
Problem
Existing optical path control devices for shifting image light axes, such as those using a yoke to guide magnetic fields, result in a large device size due to protrusions, which is not suitable for miniaturization.
Innovation Solution
An optical device with a plate-shaped optical section, a movable section supported by a shaft, and a pair of coils with a permanent magnet, where the coils are positioned to generate a magnetic field efficiently, allowing for a thinner design and improved driving characteristics, and the use of resin materials to reduce resonance frequency and temperature-induced swing trajectory changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a yoke is used to guide the magnetic field in the driving mechanism, then the magnetic field can be effectively guided, but the device size increases due to protrusions
Solution Approach 1:
The patent removes the yoke component from the magnetic field guidance system and replaces it with a magnetic field guide layer formed directly on the substrate. This extraction of the protruding yoke structure eliminates the thickness increase while maintaining effective magnetic field guidance through the alternative planar layer configuration
Solution Approach 2:
The patent introduces a magnetic field guide layer as an intermediary between the permanent magnet and the air gap. This intermediate layer, formed by sputtering or similar processes, serves the magnetic field guidance function previously performed by the yoke, but in a planar configuration that does not increase device thickness
2Length of stationary object
If the optical device is made thinner by repositioning coils, then device size is reduced, but driving characteristics may be compromised
Solution Approach 1:
The patent repositions the coil surfaces to be located between the main surfaces of the optical section in the planar dimension, rather than having them protrude in the thickness dimension. This dimensional rearrangement allows the coils to be embedded within the device thickness while maintaining their electromagnetic coupling with the permanent magnet, thus reducing overall device thickness without compromising driving characteristics
Solution Approach 2:
The patent creates local variations in the magnetic circuit path by positioning coils at specific locations between the optical section surfaces and using a magnetic field guide layer with specific magnetic permeability properties. This localized optimization ensures that the magnetic field distribution and driving force are maintained despite the reduced overall device thickness
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 optical device achieves miniaturization while maintaining excellent driving characteristics and display quality, enabling higher resolution image projection by shifting the optical axis of light through refraction, thus enhancing the apparent pixel count.
Implementation Method 1
a pair of coils that are disposed opposite to each other with the permanent magnet interposed therebetween and that generate a magnetic field to act on the permanent magnet
Implementation Method 2
light (image light) incident on the glass plate is refracted to shift the axis
Data Source
AI summary
An optical device includes a glass plate, a movable section that supports the glass plate, a shaft section that supports the movable section so as to be swingable around the swing axis, a support section that supports the shaft section, a permanent magnet that is provided in the movable section and is thinner than the glass plate, and a pair of coils that are disposed opposite to each other with the permanent magnet interposed therebetween. The movable section includes thin wall portions that are thinner than the glass plate. The permanent magnet is disposed in the thin wall portions. In side view, the surface of each of the coils on the permanent magnet side is located between both the main surfaces of the glass plate.