Head-Mounted Display Ambient Light Adaptation
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Solution Overview
Problem
Existing display devices face challenges in maintaining good contrast of the image relative to the surrounding environment, as ambient brightness can fluctuate significantly, and existing solutions are inefficient in adapting to these changes.
Innovation Solution
A display device equipped with a detector connected to a control unit that measures ambient light intensity using multifunctional glass, allowing the control unit to adjust image brightness accordingly, while utilizing a beam splitter and phototropic layers for optimal contrast and minimal scattered light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate light sensor is used to measure ambient brightness, then ambient light intensity can be detected, but the optical structure becomes more complex and adaptation to ambient brightness is insufficient
Solution Approach 1:
The first decoupling section is designed to serve dual purposes: it couples ambient light into the multifunctional glass for measurement by the detector, and simultaneously couples the generated image into the multifunctional glass for display. This eliminates the need for a separate optical path for ambient light measurement, simplifying the overall optical structure while maintaining accurate ambient brightness detection capability
Solution Approach 2:
The patent merges the ambient light measurement function with the image coupling function by using the same first decoupling section and detector for both purposes. The detector is positioned to receive light from the first decoupling section, which contains both ambient light and image light, enabling integrated measurement and display through a unified optical path
2Ease of operation
If the image generation module operates continuously, then the image is always visible, but scattered light from the image generation module interferes with ambient light intensity measurement
Solution Approach 1:
The image generation module is operated periodically rather than continuously. During each measurement cycle, the image generation is temporarily interrupted to allow accurate ambient light intensity measurement by the detector. The image generation then resumes, creating alternating periods of image display and ambient light measurement. This periodic operation eliminates scattered light interference during measurement while maintaining overall image visibility
Solution Approach 2:
The measurement process is performed by skipping or pausing the image generation temporarily for brief measurement intervals. This allows the detector to capture accurate ambient light intensity data without interference from the image generation module, then quickly returns to normal image generation operation
3Illumination intensity
If the image brightness is increased to maintain contrast in bright environments, then the image becomes more visible, but energy consumption increases
Solution Approach 1:
The image brightness is made dynamic rather than static. The control unit continuously adjusts the image generation module's output brightness based on real-time ambient light intensity measurements from the detector. In bright environments, the image brightness is automatically increased to maintain contrast; in dim environments, the brightness is reduced. This dynamic adaptation ensures optimal image visibility while minimizing unnecessary energy consumption in varying lighting conditions
Solution Approach 2:
A feedback control loop is established where the detector measures ambient light intensity and provides this information to the control unit, which then adjusts the image generation module's brightness accordingly. This closed-loop feedback system automatically optimizes image brightness to match ambient lighting conditions, ensuring good contrast while avoiding excessive energy consumption in bright environments
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 enables excellent adaptation to ambient brightness, maintaining desired contrast by varying image brightness based on environmental conditions, ensuring the image is perceivable with optimal clarity.
Implementation Method 1
A phototropic layer can be formed on the front of the multifunctional glass. This can be designed either as a passive or as an active layer whose transmittance can be controlled. Since the ambient brightness is measured after passing through the phototropic layer, the influence of the reduction in transmission due to the phototropic layer is immediately taken into account.
Implementation Method 2
a beam splitter can be arranged between the second coupling-out section and the image generation module, which directs the light coupled out from the second coupling-out section onto the detector
Implementation Method 3
the light is guided along an image beam path B to the decoupling section 9 due to three internal total reflections
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a display device having a holding device (2) which can be worn on the head of a user, a multifunctional glass (4) which is fastened to the holding device (2), through said glass the user can perceive the real environment when the holding device is worn, said glass comprising a first and second coupling-out section (9, 7) and a coupling-in section (7), an image generation module (5) which produces an image and couples said image into the multifunctional glass (4) through the coupling-in section (7) in such a way that said image is led in the multifunctional glass (4) to the first coupling-out section (9) which when the holding device (2) is worn effects a redirecting of the image in the direction of the user in such a way that the user can perceive the image in superimposition with the real environment, and a control unit (12) for the image generation module (5). The display device comprises a detector (11) which is connected to the control unit (12) and which measures the intensity of ambient light coupled through the first coupling-out section (9) into the multifunctional glass (4), guided in said multifunctional glass (4) to the second coupling-out section (7), and coupled out of the multifunctional glass (4) through the second coupling-out section (7), wherein the control unit (12) controls the brightness during generation of the image by way of the image generation module (5), the brightness being controlled according to the intensity measured by the detector (11).