Head-Up Display Polarization Control for Luminance Uniformity
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Solution Overview
Problem
Existing head-up display devices face challenges in maintaining appropriate luminance and uniformity ratio of illumination when switching between virtual and real image displays due to differences in light distribution characteristics, leading to discomfort for viewers.
Innovation Solution
A head-up display device with an imaging optical system using polarization states and a control unit to manage backlight power consumption and light source activation, ensuring consistent luminance and uniformity by adjusting power and light source usage based on display mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same backlight brightness is used for both virtual image and real image display, then the device complexity is reduced, but the luminance and brightness uniformity deteriorate due to different light distribution characteristics
Solution Approach 1:
The patent applies dynamics by making the backlight brightness adjustable based on display mode. The control unit dynamically changes the backlight luminance - using higher brightness for real image display and lower brightness for virtual image display. This dynamic adjustment resolves the contradiction by adapting the backlight characteristics to match the different optical requirements of each display mode, ensuring optimal luminance uniformity without requiring overly complex fixed systems
Solution Approach 2:
The patent changes the luminance parameter of the backlight depending on the display mode. The control unit adjusts the backlight brightness parameter - setting it to a first luminance level for real image display and a second luminance level (lower than the first) for virtual image display. This parameter change allows the system to optimize performance for each mode while maintaining a relatively simple overall structure
2Illumination intensity
If the backlight brightness is increased for real image display, then the luminance of real image improves, but the power consumption increases
Solution Approach 1:
The system dynamically adjusts backlight power consumption based on display mode. During real image display, the backlight operates at higher power to provide sufficient luminance. During virtual image display, the backlight operates at lower power since less brightness is needed. This dynamic power management ensures adequate luminance when required while minimizing energy consumption during normal operation
Solution Approach 2:
The patent changes the power consumption parameter of the backlight according to display mode. The control unit sets the backlight to a first power level during real image display and a second power level (lower than the first) during virtual image display. This parameter adjustment directly addresses the contradiction by matching power input to actual display requirements
3Device complexity
If a single lens group is used for both virtual and real image display, then the device complexity is reduced, but the luminance and uniformity ratio cannot be optimized for both modes simultaneously
Solution Approach 1:
Rather than using multiple lens groups, the patent employs a single lens group whose performance is optimized through dynamic backlight adjustment. The control unit adapts the backlight characteristics to compensate for the fixed optical properties of the single lens group, ensuring acceptable luminance and uniformity ratio for both virtual and real image display modes while maintaining low device 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
The solution minimizes brightness differences during mode transitions, reducing viewer discomfort and ensuring appropriate luminance and uniformity in both virtual and real image displays.
Implementation Method 1
a first reflection member having, as a polarization state, a first polarization state and a second polarization state different from each other in transmittance, and a second reflection member reflecting the display light transmitted through the first reflection member and in which first display light in the first polarization state is emitted through a first optical path reflected by a surface of the first reflection member
Implementation Method 2
first display light in the first polarization state is emitted through a first optical path reflected by a surface of the first reflection member
Implementation Method 3
second display light in the second polarization state is transmitted through the first reflection member, is emitted through a second optical path reflected by the second reflection member, and forms the real image
Data Source
AI summary
A head-up display device includes an imaging optical system with a first reflection member, differing in transmittance between two polarization states, and a second reflection member. Display light in the first polarization state forms a virtual image via the first reflection member, while light in the second polarization state forms a real image via the second reflection member. A control unit manages the polarization state and toggles the backlight's light sources. When displaying a virtual image, the control unit activates at least one light source, and for a real image, it activates at least one light source with higher power consumption than for the virtual image.