Dual Backlight Timing Control for Luminosity Uniformity in OCB Displays
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Solution Overview
Problem
Liquid crystal display devices using the OCB mode face issues with uniform luminosity and power efficiency, particularly when switching light direction for 3D displays, leading to luminosity inclination and reduced brightness during 2D image display.
Innovation Solution
A liquid crystal display device with a dual back light system, where the first and second lighting units are independently controlled to alternate their on and off periods based on the scanning direction of the gate lines, ensuring that the light intensity is inclined to reduce luminosity inclination and enhance power efficiency during both 3D and 2D displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the back light is always turned on to maintain high luminosity uniformity, then the luminosity uniformity is improved, but the power consumption increases and electric power efficiency deteriorates
Solution Approach 1:
The back light is operated periodically rather than continuously. During the black display period in the time-sharing 3D display operation, the back light is turned off to save power. During the image display period, the back light is turned on to provide necessary illumination. This periodic operation reduces overall power consumption while maintaining luminosity uniformity during active display periods.
Solution Approach 2:
The back light is turned on in advance before the image signal writing is completed and is kept on until the liquid crystal response is complete. This preliminary and extended lighting ensures that when the image is displayed, the luminosity is already uniform and stable, avoiding the need for continuous lighting throughout the entire frame period.
2Use of energy by moving object
If the back light is turned on after image signal writing to improve power efficiency, then the power consumption is reduced, but luminosity inclination occurs due to liquid crystal response time variations
Solution Approach 1:
The back light is turned on before the image signal writing is completed and is maintained on until the liquid crystal response is complete. This preliminary action ensures that the liquid crystal has sufficient time to respond uniformly across all pixels before the back light is turned off, preventing luminosity inclination while still allowing the back light to be off during black display periods for power savings.
Solution Approach 2:
The back light control is synchronized with the liquid crystal response time. The system monitors or estimates the liquid crystal response completion and adjusts the back light timing accordingly, ensuring the back light remains on until uniform response is achieved across all pixels, thereby preventing luminosity inclination.
3Use of energy by moving object
If the back light is turned on after half-panel writing to reduce power consumption, then the power efficiency is improved, but the luminosity inclination increases due to combined black image display and response time effects
Solution Approach 1:
The back light is turned on in advance before image signal writing completes and is kept on until liquid crystal response is complete, rather than waiting until after half-panel writing. This ensures uniform illumination across the entire panel during the display period, preventing luminosity inclination while still enabling power savings during black display periods.
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 suppresses luminosity inclination and improves power efficiency by adjusting the lighting timing and intensity of the dual back lights, maintaining high display quality and low power consumption for both 3D and 2D displays.
Implementation Method 1
liquid crystal molecules are prevented from an inverse-transition from a bend alignment state to a splay alignment state by impressing an image signal and an inverse-transition prevention signal to the liquid crystal layer periodically
Implementation Method 2
a back light to illuminate an entire display area
Data Source
AI summary
In one embodiment, an array substrate includes a plurality of gate lines extending in a column direction. A lighting device includes a first lighting unit, a second lighting unit, and a lighting driver to light on and light off the first and second lighting units independently. The first lighting unit includes a first light source arranged on a scanning starting side of the gate lines. The second lighting unit includes a second light source arranged on a scanning terminating side of the gate lines. The lighting driver lights on the second lighting unit after lighting on the first lighting unit, and lights off the second lighting unit after lighting off the first lighting unit in a period between a starting time to write a first signal and a finishing time to write a second signal in the plurality of pixels.