Moisture Absorption Member for Optical Deflection Unit
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Solution Overview
Problem
The influence of moisture on the optical characteristics of deflection units in head-mounted displays, particularly those using hologram diffraction grating films, leads to changes in pitch and inclined angles, affecting the performance and stability of the display.
Innovation Solution
Incorporating a moisture absorption member within the sealed space surrounded by the substrates and sealing member, along with a protective film, to control humidity and maintain the optical integrity of the deflection unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a photopolymer material is used for the deflection unit to reduce weight, then the weight of the display device is reduced, but the optical characteristics (pitch and inclined angle) change due to moisture absorption
Solution Approach 1:
A moisture absorption member is introduced as an intermediary substance within the sealed space to absorb moisture and prevent it from affecting the photopolymer deflection unit. This mediator protects the optical characteristics while allowing the use of lightweight photopolymer material
Solution Approach 2:
The sealed space creates a protected environment around the deflection unit, and the moisture absorption member maintains this environment by actively removing moisture, effectively creating a moisture-free inert atmosphere that preserves optical characteristics
2Reliability
If the deflection unit is sealed to prevent moisture ingress, then the optical characteristics are protected, but the device complexity increases
Solution Approach 1:
A thin sealing member (film) is used to seal the edges of the substrates, creating a protective barrier against moisture ingress. This flexible film approach provides effective sealing while adding minimal structural complexity and maintaining device compactness
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 effectively suppresses the impact of moisture on the deflection unit's characteristics, ensuring stable and consistent performance while reducing the weight of the display device.
Implementation Method 1
a moisture absorption member which is disposed in a space surrounded by the first substrate, the second substrate, and the sealing member
Implementation Method 2
a deflection unit which is disposed on the light guide plate 121. Specifically, the deflection unit is configured of a first diffraction grating member 141 and a second diffraction grating member 142 which include a reflective volume hologram diffraction grating film
Data Source
AI summary
An optical device, includes: a first substrate 121 including a first surface 121A and a second surface 121B; a second substrate 122 including a first surface 122A and a second surface 122B; deflection units 141 and 142 disposed on the first surface 121A of the first substrate 121; a sealing member 124 sealing an outer edge portion of the first surface 121A of the first substrate 121 and an outer edge portion of the first surface 122A of the second substrate 122; and a moisture absorption member 130 disposed in a space which is surrounded by the first substrate 121, the second substrate 122, and the sealing member 124.