Light Guide Plate Deflection Control for Single Focus Point Projection
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Solution Overview
Problem
Existing image display devices for cross reality applications often project multiple focus points to the pupil simultaneously, leading to a lack of deep focal depth and resulting in unclear images for observers.
Innovation Solution
An image display device comprising an image formation unit, a light guide plate with multiple paths for internal total reflection, and a control unit that selects deflection portions based on pupil position to prevent multiple focus points from being projected simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple paths with deflection portions are provided in the light guide plate to expand the eye box, then the viewing area is improved, but multiple focus points are projected to the pupil simultaneously causing deep focal depth to deteriorate
Solution Approach 1:
The patent applies dynamics by making the light guide plate switchable between different operating states. The plate can dynamically select which deflection portion to activate based on real-time eye position detection, transitioning between a first state (activating first deflection portion) and a second state (activating second deflection portion) to maintain single focus point projection while expanding effective viewing area
Solution Approach 2:
The patent changes the operational parameters of the light guide plate by controlling which specific deflection portion is activated. By adjusting the selection of active deflection portions based on detected eye position, the system modifies optical path parameters to ensure only one focus point is projected at a time, thereby maintaining deep focal depth while accommodating eye movement within an expanded eye box
2Adaptability or versatility
If multiple deflection portions are activated simultaneously to cover larger pupil movement range, then the adaptability is improved, but the image clarity deteriorates due to multiple focus points
Solution Approach 1:
The system employs self-service through automatic eye position detection and automated selection of the appropriate deflection portion. The detection unit continuously monitors eye position and the control unit automatically switches between deflection portions without user intervention, ensuring the system always operates in a state that provides both adaptability to pupil movement and maintains image clarity through single focus point projection
Solution Approach 2:
The patent implements feedback by using the detection unit to continuously monitor eye position and feeding this information back to the control unit, which then adjusts which deflection portion is activated. This closed-loop feedback mechanism ensures the system adapts to pupil movement while maintaining image clarity by preventing simultaneous activation of multiple deflection portions that would create multiple focus points
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 effectively prevents multiple focus points from being projected to the pupil at the same time, ensuring a clear and focused image for the observer by adjusting the deflection portions based on pupil position.
Implementation Method 1
a light guide plate which emits the image light, entering from the image formation unit, to a pupil of an observer
Implementation Method 2
each of the paths includes at least one deflection portion which forms a focus point in the pupil
Data Source
AI summary
It is a principal object of the present invention to prevent multiple focus points from being projected to the pupil at the same time. The present invention provides an image display device including an image formation unit, a light guide plate that emits image light entering from the image formation unit, to a pupil of an observer, a detection unit that detects a position of the pupil, and a control unit that controls the image formation unit. The light guide plate has at least two paths that perform internal total reflection and guidance of the image light entering therein. Each of the paths includes at least one deflection portion that forms a focus point at the pupil. The control unit makes a selection from the deflection portions on the basis of position information of the pupil.