Backlight Unit Sequential Drive Matrix for LCD Video Drag Reduction
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Solution Overview
Problem
Liquid crystal display (LCD) backlight units face challenges in reducing video drag and flicker, and require a large number of drivers to supply power to light sources, increasing manufacturing costs.
Innovation Solution
A backlight unit with a light source unit divided into independently driven areas, arranged in a matrix form, where the drive power is supplied sequentially in synchronization with the scanning period, and the lighting periods are adjusted based on the type of image signal, reducing the number of drivers needed and preventing overlap in turn-on sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light source unit is divided into multiple division areas with independent drivers, then video drag and flicker are reduced, but the number of drivers increases, increasing manufacturing cost
Solution Approach 1:
Multiple division areas are combined into a single light source unit that is controlled by one driver. The driver sequentially supplies drive power to multiple division areas within one frame period, achieving the benefits of divided control without requiring multiple independent drivers, thus reducing manufacturing cost while preventing video drag and flicker
Solution Approach 2:
The driver supplies drive power to division areas in a periodic sequential manner, turning on different division areas at different time points within one frame period. This periodic activation pattern prevents simultaneous illumination that causes video drag and flicker, while using a single driver to control multiple areas
2Illumination intensity
If the lighting period is extended to cover the entire scanning period, then still images are displayed with sufficient brightness, but motion images exhibit video drag
Solution Approach 1:
The lighting period is made dynamic and adaptable based on the type of image signal. The system detects whether the displayed content is a still image or motion image and adjusts the lighting period accordingly: using a longer period for still images to maintain brightness, and a shorter period for motion images to prevent video drag
Solution Approach 2:
The lighting period parameter is changed based on the image signal type. For still images, the lighting period is extended to the entire scanning period to ensure sufficient brightness. For motion images, the lighting period is reduced to prevent video drag, thus optimizing display quality for different content types
3Ease of operation
If multiple drivers are used to supply power to division areas, then independent control of each area is achieved, but manufacturing cost increases
Solution Approach 1:
Multiple division areas that require independent control are merged into a single light source unit controlled by one driver. The driver sequentially activates different division areas within one frame period, achieving independent control functionality without the cost of multiple drivers, thus improving ease of manufacture while maintaining operational flexibility
Data Source
AI summary
A display apparatus includes: a display panel; a light source unit which comprises a light source and has a plurality of division areas which are separated and independently driven each other, and is located at the back of the display panel; a drive unit which supplies drive power for the light source unit; and a light source controller which controls the drive unit so that the drive power can be supplied sequentially to the division areas which are divided in a first direction, in synchronization with a scanning period for which one frame of an image signal is displayed, and a lighting period of the division areas can be changed according to the kind of the image signal which is displayed on the display panel.