Head-Up Display Backlight Control for Border Visibility
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Solution Overview
Problem
Head-up display devices struggle to prevent the visual recognition of borders between the black brightness of the display area and the background in dark environments due to insufficient contrast ratio, which degrades the image quality.
Innovation Solution
The head-up display device controls the backlight brightness based on environmental illuminance to maintain a specific brightness ratio or difference that prevents the border from being visually recognized, using a control circuit and illuminance sensor to adjust the backlight brightness according to expressions derived from experimental data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight brightness is increased to improve the black brightness of the display area, then the contrast ratio improves, but the border between the display area and background becomes more visually recognizable in dark environments
Solution Approach 1:
The patent applies dynamics by making the backlight brightness adjustable and adaptive rather than fixed. The control circuit dynamically adjusts the backlight brightness based on environmental illuminance conditions, switching between a first brightness level in bright environments and a second brightness level in dark environments. This dynamic adaptation resolves the contradiction by optimizing the black brightness of the display area for each condition while preventing border visibility in dark environments.
Solution Approach 2:
The patent applies parameter changes by modifying the backlight brightness parameter according to environmental conditions. The control circuit changes the brightness parameter between two distinct levels based on illuminance sensor input, thereby adjusting the black brightness of the display area to maintain appropriate contrast ratios in bright environments while reducing border visibility in dark environments.
2Illumination intensity
If the contrast ratio is increased to prevent border recognition in dark locations, then the image quality improves, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent applies dynamics by implementing a control circuit that automatically adjusts backlight brightness based on environmental illuminance. This dynamic control mechanism achieves high contrast ratios in dark locations without requiring complex manual intervention or multiple hardware components, as the system adapts automatically to lighting conditions.
Solution Approach 2:
The patent applies feedback by using an illuminance sensor to detect environmental light conditions and providing this information to the control circuit. The control circuit then adjusts the backlight brightness accordingly, creating a closed-loop feedback system that maintains optimal contrast ratios while preventing border recognition in dark environments without excessive complexity.
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 effectively prevents the border between the display area and the background from being visually recognized, enhancing image quality by maintaining a suitable brightness difference or ratio, thereby improving the display's contrast in varying lighting conditions.
Implementation Method 1
a liquid crystal display device that displays an image by allowing the illumination light to pass through
Implementation Method 2
reflects display light, which is illumination light emitted from a backlight and having passed through the liquid crystal display device, with a reflecting mirror
Data Source
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AI summary
A head-up display device (10) includes: a light source (12); a liquid crystal display device (13) that controls a transmittance of light from the light source (12) and displays an image on a display member (15); an illuminance sensor (18) that measures an environmental illuminance; and a control circuit (20) that uses a measurement result of the illuminance sensor (18) to control a brightness of the light source (12). The control circuit (20) controls the brightness of the light source (12) to prevent a border caused by a difference between a black brightness of a display area displayed on the display member (15) by the liquid crystal display device (13) and a black brightness of a background around the display area from being visually recognized.