Vehicle Display Illumination with Local Luminance Maxima
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Solution Overview
Problem
Display devices in vehicles, such as LCDs, suffer from sunlight washout due to reduced brightness and contrast when viewed at angles typical for drivers and passengers, leading to reduced visibility and energy wastage, as they are designed for optimal viewing along a normal to the display plane rather than the actual viewing angles of occupants.
Innovation Solution
The display apparatus is designed to have brightness and contrast that vary with viewing angle, with local maxima along directions parallel to primary vectors, allowing increased light intensity to be directed towards drivers and passengers, and includes illumination and scattering means to project light along these vectors, reducing energy consumption by adjusting illumination based on viewer presence and ambient light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the display is designed for optimal viewing along a normal to the display plane, then maximum luminance is achieved in that direction, but the brightness and contrast are reduced when viewed at typical driver and passenger angles
Solution Approach 1:
The display device creates different local luminance maxima at different angular positions by using multiple illumination sources arranged to project light through the liquid crystal panel at various angles. Each illumination source creates a localized intensity maximum corresponding to a specific viewing direction, allowing the display to provide optimal brightness for multiple viewing positions simultaneously
Solution Approach 2:
The illumination system is divided into multiple separate illumination sources, each responsible for creating a luminance maximum in a specific angular direction. This segmentation allows independent optimization of illumination for different viewing angles (e.g., driver side, passenger side, center) without compromising performance in any single direction
2Illumination intensity
If the display provides maximum luminance along the normal direction, then optimal viewing is achieved for head-on observers, but energy is wasted as light is scattered in directions not utilized by occupants
Solution Approach 1:
Instead of uniform omnidirectional illumination, the system concentrates light energy into specific angular directions where occupants are positioned. Each illumination source directs light preferentially toward its intended viewing zone, creating localized intensity maxima that match the spatial distribution of occupants and eliminate wasted scattered light
Solution Approach 2:
The display system can dynamically activate or deactivate specific illumination sources based on the presence and position of occupants. When only one occupant is present, only the corresponding illumination source needs to be active, reducing energy consumption while maintaining optimal luminance for the actual viewer
3Adaptability or versatility
If the display is positioned centrally in the dashboard, then it is visible to both driver and passenger, but the viewing angles from typical occupant positions deviate significantly from the normal direction
Solution Approach 1:
The centrally positioned display uses multiple illumination sources arranged symmetrically to address different viewing zones. One or more illumination sources are directed toward the driver side while others target the passenger side, allowing the single central display to provide optimal luminance for multiple occupants viewing from laterally displaced positions
Solution Approach 2:
The illumination sources are arranged and oriented asymmetrically relative to the display plane normal, with each source tilted at a specific angle to match the typical viewing angle from its corresponding occupant position. This asymmetric arrangement compensates for the lateral displacement of occupants from the centerline
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 configuration enhances visibility for drivers and passengers by directing maximum luminance along typical viewing angles, reducing the risk of display failure under intense ambient lighting and minimizing power consumption, especially in single-occupant journeys.
Implementation Method 1
arranged to project light through the liquid crystal panel in a first direction R1 towards an eye of a driver and a second direction R2 towards an eye of a passenger
Implementation Method 2
The apparatus may further comprise at least one scattering means, the at least one illumination means being arranged to direct light towards the at least one scattering means, the at least one scattering means being arranged in turn to scatter light in said direction parallel to the at least one primary vector
Data Source
AI summary
A display apparatus suitable for use in any of a number of different display applications including, but not limited to, mounting to a dashboard of a motor vehicle. The display apparatus includes a display portion arranged to display an image having a brightness and a contrast, the brightness and/or contrast of the image being a function of viewing angle, the brightness and/or contrast having at least one local maximum along a direction substantially parallel to at least one primary vector, the at least one primary vector not being a vector substantially normal to a plane of the display portion.