Tilted Vehicle Display Luminance Control for Uniform Virtual Images
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Solution Overview
Problem
Conventional vehicle display devices experience uneven luminance due to the tilting of the light-transmitting display unit, which leads to decreased luminance at locations far from the backlight, resulting in a less effective virtual image display.
Innovation Solution
The vehicle display device includes a control unit that adjusts the illuminance of the backlight unit based on the eye point or eye box of the occupant, ensuring that the luminance at the emission surface of the display unit is higher at the lower edges than at the upper edges, thereby reducing unevenness in luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the display unit is tilted relative to the optical axis to prevent external light glare, then glare from external light is avoided, but luminance becomes uneven with decreased brightness at locations far from the backlight
Solution Approach 1:
The patent applies local quality by differentiating the luminance control across different regions of the display unit. The control unit adjusts the illuminance of irradiation light to be higher at the first edge (lower edge in vertical direction) than at the second edge (upper edge in vertical direction), compensating for the luminance decrease caused by tilting. This regional differentiation ensures uniform virtual image luminance while maintaining the tilted configuration that prevents glare.
2Ease of operation
If the display unit is tilted to improve visibility by preventing reflected light from returning to the reflective member, then visibility is improved, but the distance variation causes luminance unevenness
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the illuminance parameter of the backlight unit based on the tilted configuration. The control unit modifies the light intensity distribution across the display unit, specifically increasing illuminance at the first edge relative to the second edge. This parameter adjustment compensates for the distance variation caused by tilting, ensuring uniform luminance output while maintaining the visibility benefits of the tilted arrangement.
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 reduces unevenness in luminance across the display surface, enhancing the visibility and clarity of the virtual image displayed to the occupant.
Implementation Method 1
a backlight unit configured to diffuse and distribute light of a light source from an irradiation surface
Implementation Method 2
a light-transmitting plate-shaped display unit configured to cause irradiation light incident from the irradiation surface to an irradiation target surface to be transmitted and emitted from an emission surface as the display light
Implementation Method 3
at least one reflective member configured to reflect the display light emitted from the display device within the housing and cause the display light to be projected onto a projection target portion within the vehicle interior
Data Source
AI summary
A vehicle display device includes a display device, a reflective member that causes the reflected light to be projected onto a projection target portion, and a control unit that controls the display light. The display device includes a backlight unit and a light-transmitting plate-shaped display unit that causes the irradiation light incident from the irradiation surface to the illumination target surface to be transmitted and emitted from an emission surface as display light. The display unit is tilted relative to the irradiation surface such that, between the irradiation surface and the reflective member, the distance between the second edges defining the lower edges of a virtual image is greater than the distance between the first edges defining the upper edges of the virtual image, and the control unit makes illuminance of the irradiation light higher at the second edge than at the first edge.