LCD Backlight Brightness Control via Histogram Analysis
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Solution Overview
Problem
Liquid crystal display devices have fixed brightness, leading to lower display brightness and contrast ratio compared to CRTs, and high power consumption and heating issues with the back light unit.
Innovation Solution
A liquid crystal display device with a histogram analyzer determining image modes (low, normal, high brightness) and a back light controller adjusting the maximum brightness of the back light unit based on these modes, along with a data modulator to enlarge the histogram and modulate image data, thereby controlling the brightness and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the back light unit uses fixed maximum brightness, then the display device can maintain stable operation, but the display brightness and contrast ratio are insufficient compared to CRT displays
Solution Approach 1:
The patent implements dynamic brightness control by analyzing the histogram of input images and automatically adjusting the back light unit's brightness level. The system transitions from fixed brightness to adaptive brightness by detecting image characteristics (dark, normal, or bright scenes) and dynamically modifying the back light output accordingly, thereby improving display brightness and contrast ratio while maintaining stable operation
Solution Approach 2:
The system changes the brightness parameter of the back light unit based on histogram analysis results. By categorizing images into three modes (dark scene, normal scene, bright scene) and adjusting the back light brightness parameter for each mode, the system achieves adaptive brightness control that enhances display quality without compromising operational stability
2Illumination intensity
If the back light unit operates at high brightness, then display quality improves, but power consumption and heating increase
Solution Approach 1:
The system dynamically adjusts the back light brightness parameter based on the analyzed image characteristics. For dark scenes, it uses high brightness to enhance visibility; for normal scenes, it uses medium brightness; for bright scenes, it uses low brightness. This parameter adaptation reduces overall power consumption while maintaining display quality when needed
Solution Approach 2:
The system periodically analyzes the histogram of incoming images and adjusts the back light brightness in response to changing scene requirements. This periodic adaptation ensures high brightness is applied only when necessary (dark scenes), reducing unnecessary power consumption during normal or bright scenes
3Illumination intensity
If the back light unit operates at high brightness, then display quality improves, but heating of the back light unit increases
Solution Approach 1:
The system adjusts the back light brightness parameter dynamically based on scene analysis. By reducing brightness during normal and bright scenes, the system decreases thermal generation in the back light unit, thereby controlling temperature and preventing overheating while maintaining display quality during dark scenes when high brightness is necessary
4Device complexity
If the back light unit has fixed brightness, then the device structure remains simple, but the contrast ratio and display quality deteriorate
Solution Approach 1:
The system implements a feedback mechanism where the histogram analyzer continuously monitors image characteristics and provides control signals to adjust the back light brightness. This feedback loop enables automatic adaptation to different scene requirements, improving contrast ratio and display quality without requiring complex manual intervention, as the system self-regulates based on real-time image analysis
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 increases the brightness ratio, improves display quality, reduces power consumption, and decreases heating in the back light unit, enhancing the overall efficiency and image clarity.
Implementation Method 1
The inverter 14 converts DC power from a power supply 13 into AC power and boosts the AC power, to thereby generate the tube current
Implementation Method 2
The line light source includes a lamp having a discharge tube for generating white light in accordance with a tube current received from an inverter 14
Data Source
AI summary
The liquid crystal display device includes a histogram analyzer analyzing a histogram of an input image and determining the input image as being in one of a low brightness mode, a normal mode, and a high brightness mode based on the histogram analysis, a back light controller controlling a maximum brightness of a back light unit based on the mode determination, and a data modulator enlarging the histogram of the input image to modulate data of the input image. The histogram analyzer detects a most frequent value of gray scale occurring most frequently in the input image of one frame, compares the most frequent value with a predetermined low reference gray value and a predetermined high reference gray value, and determines the input image as in one of the low brightness mode, the normal mode, and the high brightness mode based on the compared result.