HMD Display Light Guide Adaptive Luminance Control
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Solution Overview
Problem
Head-mounted display devices face challenges in maintaining image visibility due to external light interference, where high ambient brightness surpasses the display's luminance, making it difficult for users to clearly recognize images.
Innovation Solution
A display device incorporating a light guide portion, semi-transmissive portion, and reflective portion, along with a light sensor, to adjust image light luminance based on sensed external light, ensuring optimal visibility by reflecting and transmitting external light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the display device outputs image light with fixed luminance, then the manufacturing process is simple, but the image visibility deteriorates under high external light conditions
Solution Approach 1:
The display device uses its own emitted image light to automatically adjust luminance levels. The light sensor detects the device's emitted light intensity and feeds back to the controller, which adjusts the driving voltage accordingly. This self-regulating mechanism eliminates the need for external light sensors while achieving adaptive luminance control.
Solution Approach 2:
The system implements a feedback loop where the light sensor continuously monitors the image light luminance and sends signals to the controller. The controller adjusts the driving voltage based on this feedback to maintain optimal luminance levels, creating a closed-loop control system that adapts to varying viewing conditions.
2Illumination intensity
If a separate light sensor is added to detect external light, then the image visibility improves under varying ambient light, but the device complexity and manufacturing cost increase
Solution Approach 1:
The light sensor serves dual functions: it detects both the device's emitted image light for luminance control and indirectly senses external light conditions through the interaction of light paths. This multi-functionality eliminates the need for separate light sensors typically required for ambient light detection in head-mounted displays.
Solution Approach 2:
The display device uses its own emitted image light to automatically adjust luminance levels. The light sensor detects the device's emitted light intensity and feeds back to the controller, which adjusts the driving voltage accordingly. This self-regulating mechanism eliminates the need for external light sensors while achieving adaptive luminance control.
3Illumination intensity
If the display device increases image light luminance to overcome external light, then the image visibility improves, but the energy consumption increases
Solution Approach 1:
The display device dynamically adjusts its luminance output based on real-time conditions. The controller modifies the driving voltage to the light-emitting layer according to feedback from the light sensor, enabling the system to optimize energy consumption by emitting only the necessary luminance level required for visible images under current external light conditions.
Solution Approach 2:
The system changes the electrical parameters (driving voltage) applied to the light-emitting layer based on detected light conditions. By adjusting voltage levels dynamically, the device optimizes energy consumption while maintaining adequate image visibility, avoiding constant high-energy emission regardless of external light conditions.
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 enhances image light luminance in response to varying external light conditions, maintaining clear image recognition for users regardless of ambient brightness levels, reducing the need for separate light sensors and enhancing manufacturing efficiency.
Implementation Method 1
a light guide portion configured to guide the image light of the display panel by reflecting the image light at least one time
Implementation Method 2
a semi-transmissive portion configured to: reflect the image light, guided by the light guide portion, toward the outside of the light guide portion, and at the same time: transmit a first portion of external light entering the light guide portion, and reflect a second portion of the external light
Implementation Method 3
a reflective portion configured to reflect the second portion of the external light, reflected by the semi-transmissive portion, toward the display panel
Implementation Method 4
the display panel includes a light sensor configured to sense the second portion of the external light reflected by the reflective portion
Data Source
AI summary
A display device includes: a display panel for outputting image light, a light guide portion for guiding the image light by reflecting the image light at least one time, a semi-transmissive portion for: reflecting the image light, guided by the light guide portion, toward the outside of the light guide portion, and at the same time: transmitting a first portion of external light entering the light guide portion, and reflecting a second portion of the external light, and a reflective portion for reflecting the second portion of the external light, reflected by the semi-transmissive portion, toward the display panel, wherein the display panel includes a light sensor for sensing the second portion of the external light reflected by the reflective portion, and wherein luminance of the image light of the display panel is changed in accordance with the amount of the external light sensed by the light sensor.