Deflection Unit Pupil Tracking for HMD Image Quality
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) using the laser scanning method face issues with pupil misalignment due to eyeball rotation, leading to incomplete image viewing and uneven luminance, and the use of multiple deflection focal points complicates the design and increases power consumption.
Innovation Solution
A display apparatus with a deflection unit that deflects beams to pass through the pupil at positions other than the center, allowing for wider rotation angles without multiple focal points, and includes a light detection system to adjust beam intensity and position for optimal viewing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple deflection focal points are provided to counter pupil misalignment, then pupil misalignment is reduced, but device complexity increases
Solution Approach 1:
The patent implements dynamic adjustment of the deflection focal point position based on detected pupil position. The system continuously monitors pupil location and adjusts the focal point accordingly, replacing the static multiple focal points approach with a dynamic single focal point system that adapts in real-time, thereby reducing device complexity while maintaining reliability
Solution Approach 2:
The patent employs a feedback mechanism where pupil position is detected and used to control the deflection focal point position. This closed-loop control system automatically compensates for pupil misalignment without requiring multiple pre-configured focal points, simplifying the device structure while ensuring accurate beam delivery to the retina
2Reliability
If multiple deflection focal points are provided to counter pupil misalignment, then pupil misalignment is reduced, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the single deflection focal point position based on real-time pupil detection, eliminating the need to maintain multiple focal points simultaneously. This dynamic approach reduces power consumption by activating only one focal point at a time while adapting its position to track pupil movement, compared to the energy-intensive static multiple focal points configuration
Solution Approach 2:
The feedback-controlled single focal point system consumes less power than multiple focal points by selectively activating only the currently needed focal position. The system detects pupil location and directs energy to a single adaptive focal point rather than maintaining multiple focal points, thereby reducing overall power consumption while effectively counteracting pupil misalignment
3Device complexity
If the deflection focal point is fixed at the pupil center, then the design is simple, but pupil misalignment occurs during eyeball rotation
Solution Approach 1:
The patent transforms the fixed focal point into a dynamic one that moves with pupil position. By implementing real-time pupil detection and focal point adjustment, the system maintains focal accuracy during eyeball rotation without complicating the overall design, as the adjustment is achieved through electronic control rather than mechanical complexity
Solution Approach 2:
The feedback mechanism detects pupil position changes during eyeball rotation and automatically adjusts the deflection focal point to remain aligned with the pupil. This simple yet effective feedback loop maintains reliability during eye movement without requiring complex multi-focal point designs, as the system adaptively tracks and compensates for pupil displacement
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 solution reduces pupil misalignment, enables continuous image viewing across wider angles, and simplifies the display apparatus design by eliminating the need for multiple focal points, resulting in improved image quality and reduced power consumption.
Implementation Method 1
a deflection unit (104, 107) which deflects, toward the user's eyes, the beams scanned by the scan units (103, 108)
Implementation Method 2
at which the beams deflected by the deflection mirror are focused is hereinafter described as a 'deflection focal point'
Data Source
AI summary
A display apparatus that displays an image on a retina of a user, the display apparatus comprising: an image output unit (100) which includes a light source (101, 110), a wavefront shape change unit (102, 109), and a scan unit (103, 108) and is configured to output display light for displaying the image; and a deflection unit (104, 107) configured to deflect, toward an eye of the user, the display light outputted by the image output unit (100). The deflection unit (104, 107) has a deflection characteristic of suppressing image distortion caused by a change in relative position of the deflection unit (104, 107) with respect to a pupil of the user.