Head-Mounted Display Laser Brightness Control
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Solution Overview
Problem
Conventional display devices that project images using laser light struggle to maintain visibility of surrounding information, making them unsuitable for applications where projected information overlaps with the environment, such as during walking or driving.
Innovation Solution
A head-mounted display device equipped with a light quantity detector, adjustable laser light emission, a light attenuator with multiple filters, and an optical scanner, which dynamically controls the brightness of the projected image based on external light conditions to ensure optimal visibility without obstructing surrounding information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light attenuation filter is used to block external light, then the laser light projection becomes clearer, but the surrounding information becomes blocked and invisible
Solution Approach 1:
The patent uses a wavelength-selective filter that transmits laser light wavelengths while blocking external light wavelengths. The filter is designed to pass specific laser wavelengths (e.g., 405nm, 450nm, 532nm, 635nm) while attenuating other wavelengths, enabling the projection image to be clearly visible without blocking the user's view of the surrounding environment.
Solution Approach 2:
The filter applies different transmission properties to different wavelength regions. Rather than uniformly blocking all external light, the filter selectively transmits only the laser light wavelengths while blocking other wavelengths, thus providing local quality differentiation in the optical path to resolve the contradiction between projection clarity and environmental visibility.
2Illumination intensity
If the laser light intensity is increased to improve projection visibility, then the projection becomes clearer, but the user experiences discomfort from excessive brightness
Solution Approach 1:
The wavelength-selective filter enables the system to use high-intensity laser light at specific wavelengths for clear projection visibility, while the filter blocks these intense wavelengths from reaching the user's eyes directly. The user sees the projection clearly through the filter but is protected from the harmful effects of excessive laser light intensity.
3Illumination intensity
If a light attenuation filter is placed to block external light, then the projection image becomes clearer, but the device complexity increases
Solution Approach 1:
The patent employs a single wavelength-selective filter with multiple transmission bands designed to pass specific laser wavelengths while blocking external light. This approach achieves clear projection images without requiring complex multi-filter configurations or mechanical switching mechanisms, thus minimizing device complexity while maintaining projection clarity.
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
Enables users to view projected information without losing awareness of their surroundings by adjusting the laser light intensity and attenuation to match ambient light levels, preventing discomfort and ensuring clear recognition of both projected and environmental details.
Implementation Method 1
a wavelength-selective filter configured to transmit the laser light
Implementation Method 2
a light quantity detector configured to detect a quantity of external light
Implementation Method 3
a laser configured to emit a laser light having a light quantity depending on a current value
Implementation Method 4
a light attenuator including a plurality of filters configured to switch an attenuation ratio so as to attenuate the laser light
Data Source
AI summary
The invention has an object to provide a display device that enables a user to obtain information from a projection image without losing information obtained from the surrounding environment.The display device is to be mounted on a head of the user for allowing the user to view a predetermined image, and includes a light quantity detector (17) to detect a quantity of external light; a laser (211R, 211G, 211B) to emit a laser light having a light quantity depending on a current value; a light attenuator (22) including filters to switch an attenuation ratio so as to attenuate the laser light; an optical scanner (15) to scan the laser light transmitted through the filter; an optical projection system (16) to project the scanned laser light to form an image; and a controller (27) to control brightness of the image by increasing or decreasing the current value and by switching the attenuation ratio of the filter, based on the light quantity of the external light detected by the light quantity detector.