LCD Luminance Control via PWM Lamp Driving
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal display devices have high power consumption due to continuously turned-on lamps, which limits their ability to achieve peak brightness for displaying vivid images like explosions or flashes, and this results in inefficient power usage.
Innovation Solution
The implementation of a luminance control method that selectively drives lamps by using pulse width modulation (PWM) to adjust the duty ratio and amplitude of the AC waveform, allowing each lamp unit to be controlled based on the average peak value of designated areas of the liquid crystal display panel, thereby optimizing brightness and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If lamps are continuously turned on to provide sufficient brightness, then illumination intensity is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic action by controlling lamps to turn on and off in cycles rather than continuously operating. The control unit activates specific lamps based on the timing and requirements of image display, creating periodic illumination patterns that match the display content needs while reducing overall power consumption.
Solution Approach 2:
The patent implements dynamics by making the lamp illumination state changeable and adaptable. The control unit dynamically adjusts which lamps are activated based on real-time display requirements, allowing the system to transition between different illumination states (on/off, partial/full brightness) to optimize both brightness and power consumption.
2Illumination intensity
If high voltage AC waveform is continuously supplied to lamps, then illumination intensity is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic action by controlling the supply of high voltage AC waveform to lamps in periodic cycles rather than continuous supply. The control unit activates lamps only during periods when brightness is required for image display, creating periodic high voltage supply patterns that reduce overall energy consumption while maintaining sufficient illumination intensity during active periods.
3Illumination intensity
If lamps are continuously operated to provide sufficient light, then illumination intensity is improved, but the efficiency of power usage deteriorates
Solution Approach 1:
The patent implements local quality by enabling different illumination levels or lamp activation patterns for different display content requirements. The control unit can optimize power usage efficiency by activating only the necessary lamps or adjusting brightness levels to match the actual display needs, avoiding energy waste when full brightness is not required while maintaining sufficient illumination intensity when needed.
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 approach enables the liquid crystal display device to achieve high brightness differences across the screen, improving image quality and reducing power consumption by dynamically adjusting the lamp current according to the image content, making it suitable for expressing motion pictures and reducing overall power usage.
Implementation Method 1
electrons are emitted from the low voltage electrode L to collide with the inert gas inside the glass tube, thus the amount of electrons are increased in geometrical progression. The increased electrons cause electric current to flow in the inside of the glass tube, so that the inert gas is excited by the electron to emit ultraviolet ray.
Implementation Method 2
The ultraviolet rays collide with luminous phosphorus spread over the inner wall of the glass tube emitting visible light rays.
Implementation Method 3
The lamp housing 34 prevents leakage of the visible light rays emitted from each of the lamps 36 and reflects light rays, progressing to the side and the rear surfaces of the lamps 36, to the front surface, i.e., toward the diffusion plate 12, thereby improving the efficiency of the light generated at the lamps 36.
Implementation Method 4
The diffusion plate 12 directs the light emitted from the lamps 36 towards the liquid crystal display panel 2 and to be incident in an angle of a wide range.
Implementation Method 5
The optical sheets 10 narrow the viewing angle of the light emitted from the diffusion plate 12, to improve the front brightness and reduce power consumption in the liquid crystal display device.
Data Source
AI summary
An apparatus and method for controlling luminance in an liquid crystal display device includes: a liquid crystal display panel having at least two designated areas; at least two lamp units irradiating light the designated areas of the liquid crystal display panel; an arithmetic unit configured to scan image pixels within each of the designated areas of the liquid crystal display panel, to extract a peak value of the gray level of pixels, and to calculate an average peak value for each designated area; and a lamp driver configured to control the lamp units, irradiating light to each designated area, based on the average peak value.