Directional LCD Backlight Control for Passenger-Only Viewing
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Solution Overview
Problem
Existing liquid crystal display devices used in vehicles face challenges in preventing the driver from visually recognizing images displayed on a liquid crystal display device in front of the front passenger seat, which is a safety concern.
Innovation Solution
A liquid crystal display device configuration that includes a backlight module capable of switching between first light and second light, a liquid crystal display panel, and a control device. The control device generates a first offset image by reversing the color of the first image and adjusting its luminance, and alternately displays the first image and the first offset image with corresponding light emissions, ensuring the luminance of the first offset image matches the second direction when the first display image is shown.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a liquid crystal display device is disposed in front of the front passenger seat to provide entertainment to the passenger, then the passenger can view the image, but the driver can also visually recognize the image which creates a safety hazard
Solution Approach 1:
The patent applies local quality by creating different luminance characteristics in different viewing directions. The display device is designed to emit light with high luminance in the passenger direction (first direction) and low luminance in the driver direction (second direction). This is achieved through directional light emission control, where the same display content is presented but with direction-dependent luminance modulation, allowing the passenger to view the image clearly while the driver cannot visually recognize it due to insufficient luminance in the driver's direction.
2Object-affected harmful factors
If the luminance in the second direction (driver direction) is reduced to prevent driver from seeing the image, then driver safety is improved, but the overall visibility and brightness of the display may be compromised
Solution Approach 1:
The patent resolves this contradiction by applying local quality through directional luminance control. Instead of uniformly reducing luminance across all directions, the system maintains high luminance in the passenger direction while reducing it only in the driver direction. This selective luminance distribution ensures that the display remains bright and visible for the intended user (passenger) while simultaneously preventing the driver from visually recognizing the image, thus maintaining overall display quality without compromising safety.
Solution Approach 2:
The patent employs asymmetry by creating an asymmetric luminance distribution pattern. The display emits asymmetric light intensity in different directions: high intensity toward the passenger seat and low intensity toward the driver seat. This asymmetric radiation pattern is fundamentally different from conventional symmetric displays that emit equal luminance in all viewing directions. The asymmetric design allows the same display to serve different functions for different viewers, maintaining high visibility for the passenger while ensuring invisibility for the driver.
Data Source
AI summary
A liquid crystal display device includes a backlight module configured to switch between first light having a maximum luminance in a first direction and second light having a maximum luminance in a second direction different from the first direction and emit the first light and the second light from a main surface, a liquid crystal display panel, and a control device. The control device receives a first image and generates a first offset image based on the first image, the first offset image being an image obtained by reversing a color of the first image and having a luminance adjusted, controls the liquid crystal display panel such that a first display image including the first image and a second display image including the first offset image are alternately displayed, and controls the backlight module so that the first light is emitted when the first display image is displayed and the second light is emitted when the second display image is displayed. A luminance of the first offset image is substantially equal to a luminance in the second direction when the liquid crystal display panel displays the first display image.